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THE BD-5 BULLETINA quarterly publication by and for BD-5 enthusiasts

April-June 2000Issue 24

Inside this Issue

1 • Bulletin #23 Welcomed!• Call for Authors• Nosegear Parts Located

2 • Lester Berven's BD-5Flight Test ProgramReport

7 • Alturair Introduces SpunAluminum Main Gear Legs

8 • US Patent # 3,991,487,The Truck-A-Plane

19 • BD-5 Vendor Listing• Misc Vendor Listing

20 • Late Breaking News

The BD-5 BulletinOfficial Publication the BD-5 NetworkJuan Jimenez, Director & EditorRich Perkins, FounderPO Box 155293Ft Worth TX 76155-0293Flybd5@hotmail.com

Bulletin #23 WellReceived!It has now been two weeks since Icompleted the task of photocopying,stapling, tabbing, labeling andapplying postage to some 857 issuesof the Bulletin, including 49 mailedto Canada and 68 others to variouscountries around the world.

Judging from the comments I'vereceived, I think it is safe to describethe rebirth of the Bulletin as anunqualified success.

As you can see, this issue is greatlyexpanded. Some of the material thatyou will see here is available on theweb site, such as Les Berven's flighttest report to the Society of TestPilots. We have also included greatnews about the BD-5's main landinggear, and a complete transcript ofthe US Patent award to Jim Bede forthe Truck-A-Plane design in 1976.Enjoy!

Call for AuthorsDo you enjoy writing and passing oninformation for the enjoyment ofothers? Do you have a personalcomputer? If so, here's your chanceto gain notoriety and fame in theBD-5 community.

The Bulletin needs authors to writearticles about subjects related to theBD-5. Some ideas: constructiontips, avionics, electrical systems,flight test reports, historical tidbitsand just about anything else you canthink of.

Interested? Email Juan Jimenez atflybd5@hotmail.com or mail yourmanuscript to the address listed on

the left hand corner of this page.You do the writing and Juan willtake care of the editing!

Nosegear PartsLocatedLast month we talked about aproblem that is common to Gerdesnosegear struts that are not cleanedon a regular basis.

Specifically, we talked about thedegradation of the teflon disk,spring and ball bearing that make upthe centering mechanism of thenosewheel castering system. Wethought that parts could not belocated. Well, we were wrong.

Paul Ross of Alturdyne wrote to usin March and deservedly chided usfor not checking with him first. Sureenough, Paul has the necessary partskit. The cost? A whopping threedollars and fifty cents. Call Paul at619-449-1570, fax at 619-442-0841or email him at any time atalturdyne@worldnet.att.net to getyour kit.

On a personal note, as Editor andDirector of the Bulletin I am thrilledto finally have a direct line ofcommunication to Alturair. I havenever really had a lot of contact withPaul, whose company has beenaround since 1976, supplying BD-5owners and builders with parts andservices. I am very happy that thissituation has now changed,

There's more about Alturair in thisedition of the Bulletin, including animportant announcement about anew upgrade for the BD-5's landinggear design. Read on!

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BD-5 FlightTest ProgramReportBy Lester H. Berven, Chief Test Pilot,Bede Aircraft Inc.

(Originally Published in the Journal of

the Society Of Experimental Test

Pilots)

Introduction

The BD-5 is an amateur-builtgeneral aviation aircraft whichrepresents a new concept in sportaviation. The aircraft is purchased asa complete materials package and isassembled entirely by theowner/pilot.

Upon completion, the BD-5 islicensed by the FAA in theExperimental-Amateur BuiltCategory. It is restricted to a localarea defined in the aircraft operatinglimitations until it has flown 75hours, at which time the local arearestriction is removed, and it isoperated in accordance with FAR 91for homebuilts.

The BD-5 is basically a single-place,low wing monoplane pusher withseveral unique designcharacteristics. It has removablewings with a constant diameter tubespar which fits over the centersection, a two cylinder, two cycle,dual ignition, internally mountedmid-engine which drives thewooden, fixed pitch prop through aGilmore belt reduction drive systemwith a 1.6 ratio. It has manuallyretractable landing gear, and acombination push-rod/cable controlsystem which is actuated with a sidestick on the right console.

Both a long wing (21.5 ft. span) anda short wing (14.3 ft. span) areavailable.

The BD-5 was first conceived in 1967as an ultralight, self-launched glider,but in searching for an acceptablepowerplant, it was found that thehigh power to weight ratio of thesnowmobile type 2-cycle enginewould allow a very efficient poweredaircraft and development waschanneled along these lines.

Development Flight Tests

The first prototype BD-5, N500BDwas built in 1970. The fuselage wasbolted aluminum angle frameworkcovered with a molded fiberglassshell. The wing structure was analuminum tube-spar with aluminumribs and wing skins. This aircrafthad the original V-tail and waspowered by a 36 BHP Polarissnowmobile engine.

This fiberglass V-tailed prototypewas first flown in September 1971 byJim Bede. It made a total of 2flights, both in ground effect justabove the runway. These two flightsshowed a serious deficiency in bothdirectional and longitudinal stabilityand control and a redesign of the tailwas begun immediately.

The next configuration tried was aswept conventional vertical fin witha highly swept (60 degrees at theL.E.) stabilizer/elevator. High-speedtaxi tests with this configurationshowed very limited elevator powerfor rotation and a large trim changewith power due to the induced flowfrom the propeller.

Because of the great interest in theBD-5 and the large number of ordershe was receiving, Jim had previouslydecided to pay for the toolingnecessary to produce a metalfuselage, and the first all-metal BD-

5, N501BD, was being built at thistime. Because of the limitedmanpower available and thedifficulty of making modifications tothe fiberglass BD-5, Jim decided tostop development and testing of thefiberglass prototype and concentrateon getting N501BD in the air. It wasalso at this time that he decided toadd some more manpower, and hehired Burt Rutan as Director ofDevelopment and myself as TestPilot in early 1972.

The first all metal prototype,N50lBD, differed from ship #1 notonly in the fuselage design but italso had an all-flying stabilator, anAmerican made Kiekhaefer 440ccsnowmobile engine, electricallyretractable landing gear, and avariable speed drive system.

The cooling system for this engineinstallation was two NACA flushscoops (one on each side of thefuselage) from which the cooling airwas ducted down over the cylinderfins and out the rear of the fuselagein an exhaust/ejector duct.

The initial ground testing of thisaircraft began in May 1972 with anevaluation of engine starting andcooling characteristics and with lowspeed taxi tests. These tests showedthat the engine cooling was marginalon the ground and that the rudderwas effective for taxiing above 25mph IAS and that the ailerons werenoticeable above 20 mph IAS.

High speed taxi tests were begun on31 May and control effectiveness wasevaluated in 5 mph increments up to80 mph IAS. We found, as before,that the ailerons and rudder werevery effective, but that the stabilatorwas not powerful enough to lift thenose, even at 80 mph (cg was 24%mac).

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We then reballasted the aircraft to27% cg and tried it again. This time Icould rotate by accelerating to 70,pulling the power back to idle andapplying full aft stick. Once the nosecame up I could add full power andhold it there. By using thistechnique, I got the airspeed up to80 mph IAS, made the first liftoff,flew down the runway at a height ofabout 5 feet and landed after about10 second flight. Both trim andcontrollability seemed acceptable at80 mph.

Before the next flight, the main gearwas moved forward one inch and thecg was moved aft to 28% in an effortto lower the rotation speeds.

The next flight was made on 7 June1972 at a gross weight of 690 lb.Some more high speed taxi testsshowed that the power-off rotationspeeds had been lowered to 65 mphbut that it was still impossible torotate power-on. Using the old"throttle back to rotate" trick Iaccelerated to 75 mph and lifted offfor an intended flight around thepattern.

Acceleration to 80 mph was normaland I added a little back pressure tobegin a gentle climb. The nosepitched up about twice as much as Iwanted so I added forward pressure,with no effect. I pushed evenharder, and the nose came back towhere I wanted it. I was then at 95mph IAS and about 20 feet abovethe runway.

At this point the nose began anuncommanded pitch down and ittook considerable aft stick forrecovery. This was followedimmediately by a more violent pitchup to about 2g and a pitch down toslightly negative g. At this point Idecided that this wasn't a very goodday for the first flight around thepattern.

I pulled the power back to slowdown to a previously flyable air-speed. As the airspeed decreased,the controllability improved and Imade a reasonably normal landingin the remaining runway. Aftermuch discussion and more groundtests we decided the problem couldhave been caused by having theaerodynamic center of the stabilatorforward of the pivot.

Calculation showed it to be right on,but with the highly swept stabilatorthe inflow from the prop would havemoved the center of pressureinboard, and therefore forward. Wethen changed the stabilatorgeometry to increase the area 15%and moved the pivot one inchforward to eliminate the possibilityof any instability.

With the new stabilator, the nexttaxi tests showed that the rotationspeeds had not improved, and thatwith full aft stick, the stretch in thelongitudinal control system wouldallow the stabilator to back off a full10 degrees from its static maximumof 15 degrees. This control systemdeflection plus an aerodynamicallyunstable stabilator was undoubtedlythe problem on the second flight.

Because of these problems and thefact that the stabilator with a sweepof 60 degrees was only giving us aCLmax of 0.6, we decided tocompletely redesign the longitudinalcontrol system. We changed thestabilator to an unswept trapezoidalplanform with a thicker airfoilsection, 20% more area, and a largeranti-servo tab.

During this period of redesign, theKiekhaefer 440 cc engine wasreplaced with a Hirth 650 cc and aseries of airframe/engineintegration tests were run.

The new stabilator was ready for teston 8 July 1972. To check the stickfree stability of the stabilator, wedisconnected and locked the anti-servo tab, and at 40 mph IASmeasured the stick force at full aftstick. This technique indicated avery slightly stable tail, which wasright where we wanted it. Highspeed taxi tests showed a power-onrotation speed of 50 mph IAS, and apower-off of 40 mph at a cg of 25%mac. Once the nose-wheel was off, Icould hold it off down to 30 mph.

The next flight, on 11 July 1972, wasthe first real flight of the BD-5, whenit flew away from the runway for thefirst time. Acceleration to 80 andlift-off were normal. I held theaircraft level and let it accelerate to100 mph while I made some quickstability checks and leaned themixture slightly.

Everything appeared normal, so Iraised the nose to hold 100 mph.Initial rate of climb was about 600fpm, with gear down and gw 700 lb.Cylinder head temperature at lift-offwas about 380 degrees F (450degrees F is redline). Passing theend of the runway at 500 feet, CHTwas 440 degrees F and increasing,so I started a left turn back to keyposition, still climbing.

As I turned downwind, CHT was 550degrees so I leveled off at 800 ft.,throttled back and adjusted themixture to cool down the engine.Half throttle gave about 100 mphIAS but the CHT stayed at 550degrees so I decided to return forlanding.

As I turned base, I pulled thethrottle back to idle and set up a 500fpm descent at 100 mph. Abouthalfway across base leg just to keepit interesting, the cockpit started tofill with smoke, so I lowered the

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nose to increase R/D and turnedfinal.

The smoke was getting worse and Iwasn't coming down very fast, so atabout 100 feet and just off the end ofthe runway, I shut the engine downand turned off the master switch,neither of which seemed to affectairspeed, R/D or the amount ofsmoke.

Touchdown was at about 80 mphand the smoke was really bad. Assoon as I lowered the nosewheel atabout 60 mph, I opened the canopyto clear out the cockpit and did ourfirst high speed canopy openingtests. At 50-60 mph the canopyfloated directly overhead and couldbe pushed back to full open withvery little force on it.

I taxied up to the hangar andreported the smoke, but nothingcould be found. It turned out thatthe smoke was exhaust recirculatinginto the cockpit which we fixed byinstalling a fresh air vent and sealingthe firewall better. Ground testsshowed that the cooling problemwas a lack of adequate air exit at theexhaust ejector and we wound up anadjustable cowl flap on the bottomof the fuselage. With this fix westarted flying the aircraft regularlyand were able to get the first flyingqualities data on the next severalflights.

Instrumentation

Before I describe the results of theflying qualities tests, I'd like to showyou our instrumentation system. For documentary shots, roll rate,and dynamic stability data we use anover-the-shoulder super-8 moviecamera, some film from which youhave already seen.

For stick force and position data wehave a homebuilt force grip

designed by Burt Rutan which isvery simple and surprisinglyaccurate. Stick position is read off aflexible tape threaded through thetop of the stick. Admittedly thesystem isn't very sophisticated, butit does allow us to see the variationin significant stability parameterswith cg position, which is all wewanted anyway.

Flying Qualities

Both the looks and the performanceof the BD-5 are excellent, but thething that really makes this littleairplane great is the flying qualities.Almost invariably the first questioneveryone asks is "Isn't that fast littleshort-coupled airplane going to beawful sensitive and hard to fly?"

The answer is absolutely not! It wasrecognized in the early design stagesthat very small airplanes aresometime overly sensitive and havelow control forces, and that was themajor factor in choosing a wristcontrolled side-stick for thelongitudinal and lateral control.

By decreasing the pilot's forcecapability to that available from hiswrist, the aircraft and pilot forcesare matched; and although the stickforces are very light, they feelabsolutely normal. There is notendency toward P10 orovercontrolling in any flightcondition we've investigated so far,and we've been to 240 mph IAS and5 g's, including most normalaerobatics.

I've found the same thing the AirForce studies on the side stick show;that compared to the center stick,the side stick offers more precisecontrol, a more natural seatedposition, more useable instrumentpanel space and more naturalcontrol movements. With bothforearms supported, turbulence or

aerobatic accelerations do not feedback into the controls, and fatigue isreduced on long flights.

I really believe the side stick is theoptimum system for very smallaircraft, and I don't think the BD-5would be a success without it.

Our early tests with N501BD didshow that the stick force per G wastoo light -- only about 0.75 lb/G. Onthe next several flights we increasedboth the deflection and area of thestabilator anti-servo tab and arrivedat our present optimum value ofabout 3 lb/g.

Now, that may sound a little light,but it fits perfectly from a controlharmony standpoint, and it is purelywrist action. In fact, after about 30minutes of aerobatics it feels like itmay be too much. This does bringup an interesting point, however; ifyou raise your forearm off thearmrest, the longitudinal controldynamics change considerably, andthe stick force per G becomes toolight for an inexperienced pilot, whowould then be easily capable ofoverstressing the aircraft.

I'm not sure what the solution tothat situation is, other than possiblysome kind of forearm restraint. Theresults of our longitudinal staticstability tests are shown in figure 1for two CG positions. Stick forcesand deflections are both stable as farback as 27.5% MAC. Maneuveringstick forces so far have set the aft CGlimit at 28.5% which gives a 1.5 lb/Ggradient.

At normal CG (25%) thelongitudinal short period isdeadbeat at all speeds. The phugoid,however, has a period of only 15seconds and is neutral to veryslightly damped. This is probablydue to the fixed pitch prop/highthrust line combination, which

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causes an unstable pitching momentwith speed changes.

This theory is supported by the jetBD-5 which has a much more welldamped phugoid.

Lateral/Directional Stability

Lateral directional stability is good,with positive dihedral effect andlight but well harmonized rudderforces. At 120 mph IAS a full ruddersideslip requires about 15 degrees ofbank for straight flight. Full ruddersideslips are possible from 120 mphIAS down to stall with no adversecharacteristics in either CR or PAconfiguration. Rudder fixed, thedirectional short period has afrequency of about 0.8 cps and adamping ratio of about 0.5.

There is no tendency toward dutchroll and spiral stability is neutral tovery slightly stable. Adverse yaw isquite low at cruise speed, and atapproach speed, a rudder fixed rollat about 30 degrees/sec will result inabout a one-ball sideslip on the slipindicator.

As a result, rudder/aileroncoordination is very easy and makesit a pleasant airplane to fly.Maximum roll rates are about 120degrees/sec with the long wings, and200 degrees/sec with the shortwings. Rudder power is s6mewhatlimited with the long wing andbelow 80 mph it takes full rudder forcoordinating a full deflection aileronroll.

Stalls

Stall testing has uncovered twosignificant features-one good, andone bad. The good part is the stallcharacteristics. There is a verydefinite buffet 3 to 5 mph before thebreak, and no tendency to roll offuntil you have a moderate amount of

sideslip. Up to a full ball sideslip, theaircraft will still break straightahead, and recovery is immediate ifyou relax any back pressure.

The not-so-good part is that the stallspeeds are significantly higher thanwe had expected. Data show amaximum lift coefficient of only 1.06clean and 1.45 with full flaps. Thisworks out to gross weight stallspeeds of 72 mph clean and 61 withflaps for the long wing and 86 mphclean and 74 dirty with the shortwings.

We feel this poor CLmax is due to acombination of low Reynoldsnumber, laminar separation and arelatively large tail download (15%of gw).

Current Flight Tests

We managed to get 33 flights and 25hours on N501BD and were able tocomplete most of our flying qualitiesoptimization. Both systems andperformance were non-representative, so the best we havethere is preliminary data.

In those 33 flights we had twoinflight engine seizures due to lackof adequate cooling and wound upcooling the engine from a scoop onthe bottom of the fuselage. It seemsthat the airflow has to go from theexhaust side of the cylinders to theintake side, or you get hot spotsaround the exhaust ports.

The last flight of N501BD occurredon 8 Oct 1972 and was the fourthflight with the short wings. Take-offwas normal up until I startedleaning the mixture at about 50feet. The engine didn't respondnormally and sounded richer asspeed increased and unloaded theprop.

I continued to lean until the mixturewas full out, with no apparent effect.I was then about 300 feet over theend of the runway with no rate ofclimb. I made a left turn to line upon a convenient road and lost about150 feet in the turn. Thinking I hadpossibly leaned the mixture toomuch, I tried richening it slightly,whereupon the engine quitcompletely.

I dumped the nose to maintain asmuch airspeed as possible and putthe flaps down as I flared. It was atthis point I discovered that the shortwing BD-5 at 720 pounds and a rateof descent would not flarecompletely, even starting at best rateof climb speed (105 mph IAS).

I touched down on the road at about85 mph and an 800 fpm descent,folded the main gear aft and ran offthe left side of the road down into a10 foot ditch, up the other side andcame to a stop in a small cloud ofdust.

The airplane was in surprisinglygood shape. The major damage wasto the leading edges of the wings,wrinkled fuselage bottom, andcollapsed landing gear. The onlyinjury sustained was to a fieldmouse I mashed at the bottom of theditch.

Examination of the engine showedthat the mixture control cable hadbroken on the take-off roll and I wasunable to compensate for the richercondition of the engine at higherspeed. It appeared that it would takeabout a month to fix the aircraft.Since we had all the aerodynamicdata on ship 2 we needed, and allthe systems were non-representative, it was decided torepair it only for looks as a displayand press on with the next airplane,N502BD.

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N502BD differs from N501BD inthat it has manually retractablelanding gear, plain flaps, longer gearstruts, an integral blower fan to coolthe engine. It also has a fixed ratiodrive system with a toothed belt,and a new carburetor, calibrated forthe prop load, so that there is nolonger any requirement to changethe mixture with throttle setting andairspeed. Finally, it has a dualignition engine with a capacitor-discharge ignition system.

The first flight of ship #3 was madeon 26 March 1973 and the flightprogram has proceeded with veryfew problems since then. The newmanual landing gear works verywell-gear up or gear down takesabout half a second with very littlepitch trim change.

The landing gear lever moves nineinches and it requires only 10 lb. toactuate it. We have a total of about60 hours on N502BD now and havecompleted most of our systems andflying qualities testing.

Since N502BD's performance ismore representative of the finalconfiguration, we've attempted toget some more accurateperformance estimates. However,we have yet to get our gear doors towork properly, and we're flyingwithout a nose gear door and themain gear doors stuck open aboutan inch to an inch and a half above140 mph IAS.

The maximum power available fromour present 650 cc engine is 50 BHPat sea level and 6300 engine rpmbecause of our non-optimizedexhaust system. With thatconfiguration, the present long wingBD-5 will indicate 154 mph at fullthrottle and 7500 feet, (175 mphTAS) and about 180 mph at S.L.

Rate of climb at S.L. and 660 lbs. is900 fpm with a fixed pitch cruiseprop at a best rate of climb speed ofl00 mph. The short wing BD-5 withthe same horsepower is about 15mph faster and has 2/3 the climbrate. Take-off distance with thecruise prop is about 1800 feet forthe long wing and 2500 feet for theshort wing. These should beimproved considerably when we getour CLmax up to a better value.

BD-5J

During our development programwe came across a little turbojetengine that seemed to be just madefor the BD-5, so we built anotherairframe and installed thisTurbomecca Microturbo TRS-18engine.

It has 200 lb. thrust, and electron-icfuel control with automatic startingand was designed to operate from aplenum chamber inlet. To getenough fuel capacity (50 gallons) weincreased the gross weight of theaircraft to 950 lbs. and made anintermediate length (17 feet) fullywet wing. To take the higher grossweight landing loads, we also wentto oil/air struts all around whichwe've tested to a 10 fps touch-downat 900 lb.

First flight of the jet was made on 20July 1973 and lasted 30 minutes.The jet has all the same outstandingflying qualities of the prop BD-5

with a very smooth reliable jetengine and I doubt if there has everbeen an airplane that's more fun tofly.

Stall speeds at 800 lb. are 76 knotsclean and 65 knots with flaps. Take-off and landing distances are 1200and 800 feet, respectively. Initialrate of climb at 130 KIAS is 1600fpm and in our presentconfiguration the service ceiling is26,000 feet.

Because the oleo gear struts aresignificantly different from the fiber-glass ones, we are unable so far tocompletely retract the gear. So wenot only don't have gear doors, butthe main gear hangs down a littleover 3 inches. In this configurationmaximum speed at S.L. is 200 KIAS,decreasing to 130 KIAS, (185 KTAS)at 20,000 feet.

Right now the performance is lessthan we'd hoped for but by cleaningup the gear and improving theengine thrust output we should havea pretty good performing airplane.

Always triple-check allmeasurements. Better to triple

check than double build.

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Conclusion

So far in our BD-5 test programwe've opened up the airframeenvelope to 220 KIAS and 5g andhave completed our aerodynamicoptimization except for cleaning upthe landing gear and improving ourCLmax. The remaining systems testsare engine power and coolingoptimization and drive systemdevelopment to decrease weight andimprove the soaring capability.

The major flight tests remaining arethe envelope expansion out to aVdive of 300 mph and the spin tests.Our present schedule calls forcompletion of both of these duringthis fall, and well in advance of anyof our customer's first flights.

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Alturair to OfferSpun-AluminumMain Gear LegsAs we mentioned at the beginning ofthe Bulletin, we have some veryexciting news from Paul Ross,president of Alturair.

As you all know, the main gear legsof the BD-5 are made out of thickfiberglass sheets, which are cut andformed to become components LG-93, -94, -156 and -157. Two piecesmake up each leg.

The way the raw fiberglass piecesthat come with the kit is criticalbecause of the stress that thesepieces will take during landing. Infact, it is recommended that yousend the raw fiberglass to anexperienced shop in order for themto be cut correctly the first time.

Moreover, replacement fiberglass tomake gear legs is extremelyexpensive.

What Alturair has done is toproduce the first spun-aluminumgear legs for the BD-5! The kitreplaces the fiberglass pieces, andalso replaces the castings at thebottom of the legs, above the brakes,and we all know how these castingsare prone to breaking.

The kit, according to Paul Ross ofAlturair, is very easy to install. Theresult is a much sturdier mainlanding gear, no gear droop andbetter resistance to damage fromhard landings. At press time, the kitwas to be unveiled April 8 at theSun-N-Fun show at a show specialprice of $300. Normal retail pricehad not yet been established.

Bill Martin has been a busy beaver these past few months, racking up the hourson his N501WM. These photos were taken about three weeks before we went toprint,"at about 2000 ft AGL, 125 mph indicated in formation with an H35Bonanza," says Bill, whose test pilot was flying the BD-5. The photo with geardown is what it looked like when Bill first caught up with the BD after takeoff.

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US Patent 3,991,487:The Bede Truck-A-Plane(Ed: I have received several requestsin the past few months to run thecomplete text and drawings forJames Bede's Truck-A-Plane, theonly training device that has everbeen available to teach a pilot howto "fly" a BD-5. With ranges ofmotion limited to 10 degrees or so, itwas never very realistic, but pilotswho have "flown" it tell me that itdoes a great job of teaching peoplehow to land a BD-5. From the annalsof history of the US Patent Office, Ihave located the full patent text anddrawings. I have edited the headersslightly for publication - the actualtext of the patentis presentedintact. Enjoy!)

United StatesPatent 3,991,487Bede November16, 1976Flight trainingassembly

AbstractA flight training assembly isdisclosed comprising an airplanehaving pilot operable flight controls,a truck for propelling the airplane ata speed sufficient to achieve lift ofthe airplane, and a boom structureinterconnecting the airplane andtruck. One end of the boom isinterconnected with the truck forpivotal movement relative theretoabout horizontal and vertical axes,and the other end of the boom isinterconnected with the airplane atthe center of gravity thereof bymeans of a spherical bearingassembly. Pivotal movements of theairplane relative to the boom and of

the boom relative to the truck arelimited.

Inventors: Bede; James R. (c/oBede Aircraft, Inc., P.O. Box 706,Newton, KS 67114)

Appl. No.: 654984

Filed: February 3, 1976

Claims1. A flight training assemblycomprising a winged aircraft havingpilot operable flight controls, aground supported vehicle behindsaid aircraft with respect to thedirection of flight thereof, saidvehicle being movable along theground at a speed to achieve lift ofsaid aircraft, boom means, means

mounting said boom means on saidvehicle for pivotal movementrelative to said vehicle about ahorizontal boom axis extendinglaterally of said vehicle and about avertical boom axis, universal jointmeans pivotally interconnecting saidaircraft with said boom meanssubstantially at the center of gravityof said aircraft, said universal jointmeans supporting said aircraft forpivotal movement relative to saidboom means about a first horizontalaircraft axis extending laterally ofsaid aircraft, a second horizontalaircraft axis extending longitudinallyof said aircraft and a vertical aircraftaxis, and means limiting pivotalmovement of said boom meansrelative to said vehicle and pivotal

movement of said aircraft relative tosaid boom means.

2. The training assembly accordingto claim 1, wherein said meanslimiting pivotal movement of saidboom means includes means tocontrol the rate of pivotal movementof said boom means about saidvertical boom axis.

3. The training assembly accordingto claim 2, and means biasing saidboom means to pivot about saidhorizontal boom axis in thedirection to assist lift of said aircraftrelative to ground.

4. The training assembly accordingto claim 3, wherein said biasingmeans includes spring means.

5. The training assembly accordingto claim 1, wherein said universaljoint means is spherical bearingmeans including a spherical bearingmember and spherical bearingsupport means, a shaft supportingsaid spherical bearing member atthe center of gravity of said aircraft,said spherical bearing supportmeans being fixed on said boommeans, and said means to limitpivotal movement of said aircraftincluding resilient pad means onsaid shaft and engaged by saidbearing support means in responseto pivotal movements of said aircraftrelative to said boom means aboutsaid second horizontal aircraft axisand about said vertical aircraft axis.

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6. The training assembly accordingto claim 5, wherein said means tolimit pivotal movement of saidaircraft further includes means tolimit pivotal movements of saidaircraft relative to said boom meansabout said first horizontal aircraftaxis.

7. The training assembly accordingto claim 6, and means releaseablyconnecting said resilient pad meanson said shaft for adjusting theposition of said pad means towardand away from said bearing supportmeans.

8. The training assembly accordingto claim 7, wherein said meanslimiting pivotal movement of saidboom means relative to said vehicleincludes means to control the rate ofpivotal movement of said boommeans about said vertical boom axis,and means biasing said boom meansto pivot about said horizontal boomaxis in the direction to assist lift ofsaid aircraft relative to ground.

9. A flight training assemblycomprising, a winged aircraft havingpilot operable flight controls, awheeled motor driven vehicleincluding frame means and havingoperator controlled steering andspeed control means, a boom havinga first end, means interconnectingsaid first boom end and said framemeans for pivotal movement of saidboom relative to said vehicle about ahorizontal boom axis extendinglaterally of said vehicle and about avertical boom axis, said boomextending forwardly from saidvehicle and beneath said aircraft inthe direction from the tail of saidaircraft toward the nose thereof,said boom having a second endextending upwardly into saidaircraft, means interconnecting saidsecond end of said boom with saidaircraft at the center of gravity of

said aircraft and supporting saidaircraft for universal pivotalmovement relative to said boomabout a first horizontal aircraft axisextending laterally of said aircraft, asecond horizontal aircraft axisextending longitudinally of saidaircraft and a vertical aircraft axis,means to limit said pivotalmovement of said boom relative tosaid vehicle about said horizontaland vertical boom axes, and meansto limit said universal pivotalmovement of said aircraft relative tosaid boom about said first andsecond horizontal aircraft axes andabout said vertical aircraft axis.

10. The training assembly accordingto claim 9, and further includingspring means biasing said boomlaterally about said vertical boomaxis toward a central position withrespect to the laterally oppositesides of said vehicle.

11. The training assembly accordingto claim 9, and means includingspring means biasing said boom topivot about said horizontal boomaxis in the direction to assist lift ofsaid aircraft relative to ground.

12. The training assembly accordingto claim 9, wherein said means tolimit pivotal movement about saidhorizontal and vertical boom axesincludes bumper means mounted onsaid front end of said frame meansand arm means mounted on saidboom and pivotal therewith aboutsaid horizontal boom axis, saidbumper means and arm meansbeing cooperatively positioned tolimit upward movement of saidaircraft relative to ground.

13. The training assembly accordingto claim 12, wherein said means tolimit pivotal movement about saidhorizontal and vertical boom axesfurther includes motion dampingdevices on laterally opposite sides of

said vertical boom axis, each of saiddevices having a first endinterconnected with said framemeans and a second endinterconnected with said boom, andeach of said motion damping devicesbeing operable to damp and limitpivotal movement of said boomabout said vertical boom axis.

14. The training assembly accordingto claim 13, and spring means onlaterally opposite sides of saidvertical boom axis biasing said boomabout said vertical boom axis towarda laterally central position withrespect to said vehicle.

15. The training assembly accordingto claim 14, and means biasing saidboom to pivot about said horizontalboom axis in the direction to assistlift of said aircraft relative toground.

16. The training assembly accordingto claim 9, wherein said meansinterconnecting said second end ofsaid boom with said aircraft includesa horizontal shaft fixed to andextending across said aircraft andthrough said center of gravity, aspherical bearing member on saidshaft at said center of gravity, andbearing block means fixed on saidsecond end of said boom andsupporting said spherical bearingmember.

17. The training assembly accordingto claim 16, wherein said means tolimit said universal pivotalmovement of said aircraft includesresilient pad means positioned onsaid shaft to engage said bearingblock means in response to pivotalmovements of said aircraft relativeto said boom about said secondhorizontal aircraft axis and aboutsaid vertical aircraft axis.

18. The training assembly accordingto claim 17, wherein said pad means

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is releaseably mounted on said shaftfor adjustment towar and away fromsaid bearing block means.

19. The training assembly accordingto claim 17, wherein said means tolimit said universal pivotalmovement of said aircraft furtherincludes means to limit pivotalmovements of said aircraft relativeto said boom about said firsthorizontal aircraft axis.

DescriptionThis invention relates to the art ofeducational devices and, moreparticularly, to airplane flighttraining aids.

The present invention findsparticular utility in teaching astudent pilot the techniques oftaking-off and landing wingedaircraft. Take-offs and landings areprobably the most criticalmaneuvers in connection withflying, and proper judgment andcoordination on the part of the pilotis required to minimize thelikelihood of an accident duringtake-off and landing maneuvers.There are, of course, aircraft that areused primarily for training studentpilots, and these trainers do teachthe student all of the basicinformation required to pilot anairplane. However, due to the cost ofoperation only the minimumrequired time is devoted to the manymaneuvers to be learned, includingtake-offs and landings. While it isrecognized that more training in thetechniques of taking-off and landingan airplane would be desirable, thecost of merely taking-off, circling thefield and landing is prohibitive.Moreover, very little of the total timerequired to take-off, circle and landcan be devoted to take-off andlanding skills.

Another disadvantage in studenttraining methods heretoforeemployed is that flying, andespecially take-offs and landings, arerestricted to good weatherconditions. Accordingly, the studentpilot is not likely to have anyappreciable exposure during histraining to adverse conditions suchas a strong cross wind.

If such conditions exist at an airport,traffic is directed to the runway mostfavoring the direction of wind. Stillfurther, the student pilot is notexposed to the effect of changing thecenter of gravity of a plane, such asby passenger and/or baggageloading. It is difficult, but possible,to put a payload on an aircraft whichcauses the center of gravity to shiftbeyond a specific boundary relativeto the center of gravity when theaircraft is not loaded. Pilots aretrained to be aware of thispossibility, but very few have anyidea of the consequence of such ashift in the center of gravity and theeffects thereof on control of theaircraft.

In addition to actual in-flighttraining, there are of courseelectronic flight simulators that havebeen developed primarily formilitary and commercial airline use.These simulators are extremelyexpensive and, moreover, onlysimulate various effects on anaircraft. Accordingly, the studentpilot is still aware that he is notactually flying, whereby thecapabilities of such simulators islimited.

In accordance with the presentinvention, a training assembly isprovided which overcomes thedisadvantages referred tohereinabove, and others, andprovides training capabilitiesheretofore unattainable in

connection with pilot trainingtechniques. The training assembly ofthe present invention is comprisedof a winged aircraft having pilotoperable flight controls, a groundsupported vehicle for propelling theaircraft at a speed sufficient toachieve lift thereof, and a boominterconnecting the vehicle andaircraft. The boom has one endinterconnected with the vehicle forpivotal movement about horizontaland vertical axes, and the other endof the boom is interconnected withthe aircraft at the center of gravitythereof such that the aircraft isuniversally pivotal relative to theboom.

Preferably, the ground supportedvehicle is a truck or the likepositioned behind the aircraft,whereby the aircraft is pushed in thedirection of flight thereof. In use, aperson such as a student pilot sits inthe cockpit of the aircraft, and thetruck driver accelerates the truck toa speed sufficient to achieve lift ofthe aircraft. The student pilotoperates the flight controls so as toachieve a take-off duringacceleration of the truck and landingduring deceleration thereof. Thetraining assembly can be used on anairport runway or the like and,depending on the length thereof, thestudent pilot can also manipulatethe flight controls in the aircraft toperform other maneuvers while theaircraft remains airborne. In thisrespect, the universal jointconnection between the aircraft andboom allows the student pilot toexercise pitch, roll or banking, andyaw movements of the aircraft.Pivotal movement of the boomrelative to the truck about thevertical pivot axis enables thestudent pilot to achieve movementof the plane laterally with respect tothe path of movement of the truck,and pivotal movement of the boom

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about the horizontal axis allows thestudent pilot to maneuver inelevation.

Preferably, pitch movement of theboom upwardly relative to the truckabout the horizontal pivotal axis islimited as is yaw movement of theboom laterally of the truck about thevertical pivot axis. Likewise, it ispreferred to provide limits withregard to the pitch, roll and yawmovements of the aircraft relative

to the boom. Such limits avoid thepossibility of the student pilotmaneuvering the aircraft so as tocause damage thereto or to theboom and truck, and to avoidmovement of the aircraft into aposition which might cause lateraltilting of the drive vehicle orinstability in the control thereof.

In accordance with another aspect ofthe present invention, pivotalmovement of the aircraft relative tothe boom can be limited so thatcertain flight maneuvers are lockedout with respect to student pilotactuation of the flight controls.Accordingly, movement of theaircraft can be restricted, forexample, to pitching movementsuntil the student pilot gainsexperience with regard tocontrolling such movements. Afterthe student becomes proficient inthis control mode, the aircraft canbe permitted to roll or bank andthen, eventually, to yaw. Therefore,the student pilot gains experiencewith regard to the maneuvers one ata time. It is obvious that thisprovides a training capability whichis impossible to achieve in flighttraining in a self-propelled aircraft.

In accordance with another aspect ofthe invention, the beam is biased topivot upwardly relative to the truckabout the horizontal pivot axis. Thisin effect reduces the weight of the

aircraft on the forward end of theboom, whereby the aircraft can bemade to fly at relatively low speeds.The ability to fly at low speed can befurther increased by removing thepower plant from the aircraft toreduce the weight thereof. Thepower plant is not employed duringflight training and, accordingly, ispreferably removed. The location ofthe universal joint is then at thecenter of gravity of the aircraftwithout the power plant.

The training assembly of the presentinvention also enables a studentpilot to practice taxiing operationsand lateral movement of the aircraftalong the ground during taxiing. Itwill be appreciated too that the costof operating the training assembly isconsiderably less than the cost offlying a plane and that, in a givenperiod of operation, training time ismaximized. Moreover, maneuversincluding taking-off and landing canbe practiced safely, and trainingunder undesirable weather and loadconditions can be achieved to givethe student pilot experience withregard to the feel of such conditions.In this respect, for example, thetraining assembly can be operatedon a runway where a strong crosswind condition exists, thus to enablethe student to become proficient inmaneuvering the aircraft under suchconditions. As another example,weight can be added to the aircraftto reduce the stability thereof in thepitch direction, whereby the studentpilot can experience the loss ofstability under such conditions.Other destabilizing effects can alsobe introduced into the aircraft toexpose the student pilot to flyingconditions that could never beexperienced on a normal trainingaircraft because of the danger thatwould exist. Under all of thesenormal and abnormal conditions,the student pilot can control

maneuvering of the aircraft and,without exposure to dangerouscircumstances, experience thefeeling of actually flying the aircraft.

Accordingly, it is an outstandingobject of the present invention toprovide a flight training assemblyincluding a pilotable winged aircraftattached to a ground supporteddrive vehicle and in which theaircraft is maneuverable relative tothe ground and to the drive vehicle.

Another object is the provision of aflight training device of theforegoing character which enables atrainee to experience in-flightmaneuvering of the aircraft underconditions of maximum safety.

Still another object is the provisionof a flight training assembly of theforegoing character which enables atrainee to take-off and land theaircraft and to maneuver the aircraftin pitch, roll and yaw directionsbetween a take-off and landing.

A further object is the provision of aflight training assembly of theforegoing character which enables atrainee to experiencemaneuverability of the aircraftunder adverse weather and/or loadconditions.

Still a further object is the provisionof a flight training assembly of theforegoing character in whichmovement of the aircraft by thetrainee is constrained withinpredetermined limits to avoidmovement of the aircraft into anundesirable attitude relative to theground and/or the drive vehicle.

Another object is the provision of aflight training assembly of theforegoing character which iseconomical to construct and operateand which maximizes the useful

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training time during a given periodof operation.

The foregoing objects, and others,will in part be obvious and in partpointed out more fully hereinafter inconjunction with the description of apreferred embodiment of theinvention illustrated in theaccompanying drawings in which:

FIG. 1 is a side elevation view of aflight training assembly constructedin accordance with the presentinvention;

FIG. 2 is a plan view of the assemblyillustrated in FIG. 1;

FIG. 3 is an enlarged plan viewshowing the joint structure betweenthe boom and truck of the assembly;

FIG. 4 is a sectional elevation viewof the joint assembly taken alongline 4--4 in FIG. 3;

FIG. 5 is a plan view in section of theuniversal joint between the boomand aircraft taken along line 5--5 inFIG. 1;

FIG. 6 is a sectional elevation viewof the universal joint taken alongline 6--6 in FIG. 2; and,

FIG. 7 is a front elevation view of theuniversal joint.

Referring now in greater detail tothe drawings wherein the showingsare for the purpose of illustrating apreferred embodiment of theinvention only and not for thepurpose of limiting the invention,the flight training assembly, as seenin FIGS. 1 and 2, is comprised of aground supported vehicle A, a boomB, and a winged aircraft C. Asdescribed more fully hereinafter,boom B is mounted on the front ofvehicle A for pivotal movementabout a horizontal axis D and avertical axis E, and aircraft C is

mounted on the outer end of a boomB for universal pivotal movement ofthe aircraft relative to the boomabout the center of gravity F of theaircraft.

In the embodiment shown, vehicle Ais a pick-up type truck which, as iswell known, includes an undercarriage or frame. Such a frameincludes or may be provided with across member 10 to support thecorresponding end of boom B. It willbe appreciated that the truck hasdriver controlled steering and speedcontrol mechanisms, not illustrated.Any suitable boom structure can beemployed and, as shown, thepreferred structure includeselongated metal tubes or rods 12which are spaced apart andinterconnected by tubular crossmembers welded thereto to providea rigid, open and light weight boomstructure.

Any suitable structure can beemployed for mounting the boom onthe front end of the truck for pivotalmovement about horizontal andvertical axes. In the embodimentdisclosed, as best seen in FIGS. 3and 4, the mounting structureincludes a pair of angle ironmembers 14 having inner endssecured to vehicle frame component10 such as by welding and havingouter ends spaced forwardly of thevehicle. An angle iron cross member16 extends laterally betweenmembers 14 at the outer endsthereof and is welded thereto. A pairof support brackets 18 are welded tocross member 16, and a pair ofvertical angle iron members 20 arepivotally interconnected at theirlower ends with brackets 18 bymeans of a pivot pin component 22.Pin component 22 extends throughaligned openings in brackets 18 andmembers 20 and through a sleeve

24 having its opposite ends weldedto brackets 18.

A pair of L-shaped plate members26 are welded to the upper andlower ends of vertical members 20so that one of the legs of each of theplates 26 extends horizontally andforwardly from members 20. Thelatter legs are provided withvertically aligned openingstherethrough, laterally centrallythereof, and a sleeve 28 is alignedwith the openings through the legsand has its opposite ends welded tothe legs. The corresponding end ofboom B is provided with upper andlower cross plates 30 which arewelded to the tubular members afthe boom. Hinge arms 32 are weldedto cross members 30 laterallycentrally thereof and extendrearwardly therefrom into overlyingrelationship with the forwardlyextending legs of members 26. Hingarms 32 are provided with openingsaligned with the openings throughmembers 26 and sleeve 28, and apivot pin component 34 extendsthrough the aligned openings asshown. It will be appreciated,therefore, that the axis of pivot pin22 defines horizontal pivot axis Dand the axis of pin 34 definesvertical pivot axis E.

Preferably, upward pitch movementof boom B about axis D is limited tocontrol the extent to which theaircraft can be elevated relative toground. For this purpose, uprightmembers 20 are provided with stopmembers 36 which are weldedthereto and extend rearwardlytherefrom toward truck A. Further, across member 38 is welded to angleiron members 14 so as to be in thepath of movement of stop members36 in response to upward pitchmovement of the boom. Preferably,a pad 40 of rubber or the like isprovided between stop members 36

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and cross member 38 to cushion thestopping movement of the boomwhen the desired limit of movementis reached.

It is also desirable to limit yawmovement of boom B in laterallyopposite directions about axis E andrelative to center line G of the truck.For this purpose, a pair of supportarms 42 are welded to angle ironmembers 14 and 16 to extendlaterally outwardly and forwardlythereof. The outer ends of arms 42are interconnected with boom B bymeans of corresponding movementlimiting and damping components44 having opposite ends pivotallyinterconnected one with arm 42 andthe other with a cross member 46welded to the boom. The structure ofdevices 44 is not pertinent to thepresent invention, and any suitabledevice can be employed for limitingpivotal movement of boom B towardthe corresponding arm 42 and,preferably, cushioning suchmovement. Pneumatic or hydraulicshock absorber type devices wouldbe suitable for the intended purpose.

Further in accordance with thepreferred embodiment, it isdesirable to provide for boom B tobe biased toward a center positionwith respect to center line G of thetruck. As shown in FIG. 3, this isachieved by a tension spring 48between each arm 42 and thecorresponding side of boom B. Uponmovement of boom B in eitherdirection about axis E, one of thesprings 48 is tensioned and thustends to return the boom toward aposition in alignment with centerline G of the truck. It will beappreciated that manyarrangements for achievingcentering of the boom can bedevised. For example, centeringsprings could be employed in

conjunction with or as a componentpart of components 44.

With further regard to boom B, it isdesirable to minimize the effectiveweight of the boom in order toreduce the effective load to be liftedby aircraft C during use of theassembly. In the embodimentshown, as best seen in FIGS. 1 and 2,the effective weight of the boom isreduced by means of a lift assistingarrangement including a plurality ofspring components 50. Springs 50have corresponding ends secured ina fixed position relative to truck A,and the opposite ends of the springsare interconnected with the boomand are displaceable relative to thefixed ends. More particularly, asuitable spring frame 52 is mountedon the truck in a fixed positionrelative thereto and includes a crossmember 54 provided with a pluralityof apertures to receive the ends ofsprings 50. The opposite ends ofsprings 50 are interengaged withapertures in a cross bar 56, and thelatter cross bar is connected by acable arrangement 58 with boom Bat a location spaced forwardly ofpivot axis D. Further, cable 58 isspaced above horizontal axis D bymeans of a support bridge 60 which,in the embodiment shown, includesa pair of legs 62 welded at theirlower ends to boom B andinterconnected by a plurality ofcross members 64 which arevertically spaced apart from oneanother. Cable 58 extends acrossand rests on a given one of the crossmembers, and the forward ends ofthe cable are suitably attached to theboom. It will be appreciated thatcable 58 is adapted to be associatedwith a selected one of the crossmembers 64, thus to vary the liftingeffect of springs 50 on boom B. Anynumber of cross members can beprovided for this purpose. Moreover,it will be appreciated that

arrangements other than that showncan be employed to achieve a forceto counteract the weight of theboom.

Any suitable winged aircraft can beemployed in the training assemblyof the present invention and, in theembodiment shown, the aircraft is alight weight, single seat plane of thepusher type having a power plantbehind the cockpit and a propeller atthe tail of the plane. In order tominimize the weight of the plane,the power plant is removed,whereby center of gravity F is thecenter of gravity for the planewithout the power plant. Althoughnot shown in detail, it will beappreciated that the plane includespilot operable flight controls foroperating wing, stabilizer andrudder flaps to achieve maneuveringof the plane in flight.

As mentioned hereinabove, theplane is mounted on the forwardend of boom B by a universal jointassembly so that the plane is capableof pitch, roll and yaw movementsrelative to the boom. The structureof the forward end of the boom anda universal joint construction for thelatter purpose is shown in FIGS. 5-7of the drawing. In this respect, theforward end of the boom is providedwith metal side plates 66 which arewelded to boom tubes 12 and arelaterally spaced apart to receive aninverted L-shaped metal arm 68which is mounted between theplates such as by means of aplurality of nut and bolt assemblies70. Arm 68 extends upwardly intothe aircraft through a suitableopening in the bottom of thefuselage thereof. The free end of arm68 extends forwardly and supports aspherical bearing block assemblycomprised of bearing blockmembers 72 and 74 which areinterconnected by suitable nut and

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bolt assemblies 76. bearing blockmember 72 can be integral with arm68 or can be a separate componentwelded or otherwise mounted on thefree end of arm 68.

The inner surfaces of bearing blockmembers 72 and 74 are providedwith recesses cooperatively defininga spherical cavity 78 which receivesand pivotally supports a sphericalbearing member 80. Bearingmember 80 is apertured to receive arod 82, and the bearing member issecurely mounted on the rod in anysuitable manner to prevent bothrotational and axial displacement ofthe bearing member relative to therod. The ends of rod 82 are weldedto support plates 84 which in turnare mounted on frame components86 of the aircraft on laterallyopposite sides thereof. Preferably,the rod and plates are removablymounted on the frame componentssuch as by nut and bolt assemblies88.

Rod 82 extends horizontally in thedirection between the opposite sidesof aircraft C, and the axis of the rodpasses through the center of gravityF of the aircraft. Further, sphericalbearing member 80 is centrallylocated in the direction between theopposite sides of the aircraft,whereby the center of the sphericalbearing member coincides withcenter of gravity F. The laterallyopposite sides of bearing blockmembers 72 and 74 are providedwith openings 90 coaxial with rod82 and of a diameter sufficientlylarge to permit the desired pivotalmovement of bearing member 80relative to the boom.

As mentioned hereinabove, pivotalmovement of the aircraft in thepitch, roll and yaw directionsrelative to boom B is limited. In theembodiment shown, pivotal

movement in the yaw and rolldirections is limited by means of apair of resilient pad assemblies 92mounted on rod 82 on laterallyopposite sides of bearing blockmembers 72 and 74. Each padassembly 92 includes a circular disc94 of resilient material such asrubber suitably secured to a metalbackup plate 96 which is integralwith or attached to a hub 98. Rod 82extends through the pad assembly,and the latter is axially slidablerelative to the rod to adjust thedistance between the pad assemblyand the adjacent side of bearingblock members 72 and 74. A setscrew 100 or the like can beemployed to lock the pad assemblyin a desired position. It will be seen,therefore, that by spacing each padassembly from the correspondingside of bearing block members 72and 74, aircraft C can pivot relativeto boom B in the yaw and rolldirections to the extent determinedby such spacing. When the aircraftapproaches the desired extent ofmovement in these directions,resilient discs 94 engage thecorresponding side of the bearingblock assembly to cushion and stopthe movement.

Movement of aircraft C in the pitchdirection relative to boom B islimited, in the embodiments shown,by a stop pin 102 mounted onspherical bearing member 80 and awindow or opening 104 provided inbearing block member 74. The axisof pin 102 is on a radial line throughthe center of spherical member 80,and the pin is threaded into a recessin member 80 so as to be removabletherefrom. Window 104 is of squareor rectangular contour and has awidth in the direction between thesides of bearing block member 74sufficient to permit the desiredmovement of aircraft C in the yawdirection relative to boom B. The

head of pin 102, in the embodimentshown, is circular and the diameterthereof and the height of window104 are designed to permit thedesired extent of pitch movement ofaircraft C in opposite directionsrelative to center of gravity F. Whenthe nose of the aircraft is pitcheddownwardly pin 102 engages thelower edge of window 104 to stopthe pitch movement, and when thenose of the aircraft is pitchedupwardly pin 102 engages the topedge of window 104 to stop the latterpitch motion.

It will be appreciated from theforegoing description that pivotalmovement of aircraft C relative toboom B can be limited to just pitchmovements by positioning padassemblies 92 in abutment with theopposite sides of bearing blockmembers 72 and 74. This locks outroll and yaw movements and thusenables the student pilot toexperience and become familiarizedwith control of the aircraft in thepitch direction only. When thestudent becomes proficient in thiscontrol mode, the pad assembliescan be moved outwardly from thebearing block members to releasethe aircraft for movement in the rolland yaw directions. If desired,circular pin 102 can be replaced by apin having a width corresponding tothe distance between the sides ofwindow 104 and a height less thanthe distance between the top andbottom edges of the window. Theside edges of the latter pin would berounded at a radius of curvaturecorresponding to the distancebetween the axis of pin 102 and theside edges of window 104. This pinand window configuration wouldpermit movement of the aircraft inthe pitch and roll directions, butwould preclude movement in theyaw direction. Rolling movementwould be limited by pad assemblies

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92 in the manner describedhereinabove. Accordingly, thestudent pilot can now experienceand become familiar with control ofthe aircraft in two modes ofmovement. After the studentbecomes proficient in these controlmodes, pin 102 can be againemployed in conjunction withbearing member 80, whereby thestudent pilot is now able toexperience control of the aircraft inall three modes of movement.

The extent to which aircraft C ispermitted to pivot in the pitch, rolland yaw directions relative to boomB can of course be varied as can theextent to which boom B is permittedto pivot in the yaw and pitchdirections relative to truck A.Preferably, the limits are such as toenable the student pilot to practicetake-offs and landings and othermaneuvers of the aircraft with thedegree of freedom he would have ina normal aircraft flight, but withinlimits of aircraft movement whichmake it virtually impossible to causeany uncontrolled situation whichmight result in damage to theaircraft, boom or truck. It has beenfound that these desirable resultscan be achieved with the followingmovement limitations: aircraft pitchup 15.degree. from horizontal andpitch down 10.degree. relative tohorizontal; aircraft roll 10.degree.right and left and yaw 10.degree.right and left; boom yaw 10.degree.right or left of the center line of thetruck and boom pitch upwardlyapproximately 25.degree. relative tohorizontal. In the embodimentherein illustrated and described, thetruck is a commercially availabletruck, the boom is approximately 18feet long, and the aircraft is a BD-5single seat aircraft manufactured byBede Aircraft, Inc. of Newton,Kansas. The movement limitationsrefer to maximum degrees of

movement in connection with thepreferred embodiment.

In use, the truck driver operates thetruck to move the aircraft into adesired position on a practicerunway. During such movement, thestudent pilot controls movement ofthe aircraft along the ground andthus gains experience in taxiing theaircraft. When in position on therunway, the driver accelerates thetruck and, when the ground speed issufficient, the student pilot operatesthe flight controls of the aircraft toachieve a take-off. Following thetake-off the student pilot canexercise those controls of movementof the aircraft which have been madeavailable to him. When the truckapproaches the end of the runwaythe driver decelerates the truck andthe student pilot operates the flightcontrols to land the aircraft. Ofconsiderable advantage in use of thetraining assembly is the fact that aflight instructor can ride in the truckand communicate instructions to thestudent pilot through acommunication system between thetruck and aircraft.

While considerable emphasis hasbeen placed herein on certainstructural components of thepreferred flight training assembly, itwill be appreciated that manymodifications can be made in thepreferred embodiment withoutdeparting from the principles of thepresent invention. In this respect,for example, a ground supporteddrive vehicle other than a pickuptruck could readily be employed topropell the aircraft, and the aircraftcould be other than the particularplane herein identified. Moreover,any suitable boom structure can beemployed, and many structuralarrangements other than that

herein shown can be devised toachieve the desired mounting of theboom on the drive vehicle for pivotalmovement about horizontal andvertical axes. Likewise, manyarrangements other than that hereinillustrated and described can bedevised and employed for achievinguniversal pivotal movement of theaircraft relative to the forward endof the boom, and manyarrangements can be devised forachieving limited pivotal movementof the aircraft relative to the boomand of the boom relative to the drivevehicle. The arrangements hereinillustrated and described in thisrespect are merely illustrative ofoperable arrangements for theintended purpose. Accordingly, asmany embodiments of the presentinvention can be made and as manychanges can be made in theembodiment herein illustrated anddescribed, it is to be distinctlyunderstood that the foregoingdescriptive matter is to beinterpreted merely as illustrative ofthe present invention and not as alimitation.

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Very Last Minute News!BD-5B Sets World Record!

We have just been told byHerwig Bielig of Austria thatHorst Malligas has once againbrought the FAI Class C1a/0world speed record to the BD-5community! His Rotax 618 UL-equipped BD-5B (apparently notusing the A-wing this time) wasclocked at 351.39 km/h or189.735 knots with pilot PeterSchleichenberger (132.2 lbs) atthe controls. The new record wasset back in September but it tookthe FAI six months to issue thecertification.

Congratulations, Horst!

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BD-5 Vendor ListThe following vendors provide parts,services and kits for BD-5 builders.We list them here in alphabeticalorder, for your reference.

Alturair1405 N Johnson AveEl Cajon CA 92020-1630Ph: 619-440-5531Fax: 619-442-0481Email: alturdyne@worldnet.att.netContact: Paul RossBD-5 kits, parts, builder services,engines (rotary engine indevelopment).

BD-Micro Technologies1260 Wade RdSiletz OR 97380Ph & FAX: 541-444-1343Email: sales@bd-micro.comContact: Edward "Skeeter" KarnesFLS-5 kits (recip, turboprop, jet),parts, builder services, engines (2-stroke, turboprop).

Gerald "Jerry" Kauth9810 State Ave #9Marysville WA 98270Ph: 360-435-8109Drive system sales and upgrades,landing gear parts and assemblyservices.

Robenalt Engraving1423 BroadwayBurlingame CA 94010-2082Ph & FAX: 415-348-6262Contact: Stanley RobenaltCustom instrument panels,engraved placards.

Seneca Light AircraftSystems5479 E Cty Rd 38Tiffin OH 44883Ph: 419-585-7002Fax: 419-585-6004Contact: Matt DandarHirth aircraft engine sales.

MiscellaneousSuppliersThe following vendors carryinventories of all types of aviationgoods, tools and other items whichyou may need during your project tofinish a BD-5.

Aircraft Spruce &Specialty East900 S. Pine Hill RoadGriffin, Georgia 30223Ph: 770-228-3901Fax: 770-229-2329Order Dept: 877-4-SPRUCECustomer Service: 800-443-1448Email: east@aircraft-spruce.comweb: http://www.aircraft-spruce.comGeneral aviation parts, supplies,tools.

Aircraft Spruce &Specialty West225 Airport CircleCorona, California 91720Ph: 909-372-9555Fax: 909-372-0555Order Dept.: 877-4-SPRUCECustomer Service: 800-861-3192Email: info@aircraft-spruce.comweb: http://www.aircraft-spruce.comGeneral aviation parts, avionics,supplies, tools, instruments.

Aircraft Tool Supply Co.P.O. Box 3701000 Old U.S. 23Oscoda MI 48750Ph: 800-248-0638Telephone: 517-739-1447Fax: 517-739-1448Email: info@aircraft-tool.comWeb: http://www.aircraft-tool.comAviation tools and supplies.

The Wag-Aero Group1216 North RoadLyons WI 53148Ph: 262-763-9586Fax: 262-763-7595Order Line: 800-558-6868wagaero-sales@wagaero.comWeb: http://www.wagaero.comGeneral aviation supplies, avionics,instruments, parts.

Is your company or servicemissing from this list?

Write or email us and letus know!

Have You FinishedThe R-8 Rudder

Bracket Mod OnYour BD-5?

This ModificationIs A Mandatory

Safety Of FlightItem!

Contact YourFavorite BD-5Supplier For

MoreInformation.

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The BD-5 NewsletterOfficial Publication the BD-5 NetworkPO Box 155293Ft Worth TX 76155-0293USA

Mailing label indicates remaining issues onsubscription. If it says NONE, it's time torenew! Electronic subscriptions will noteremaining issues in body of mail.

The BD-5 Bulletin is published quarterly. Domestic US and Canadian subscriptions are priced at $25/yr, internationalsubscriptions are US$40/yr, and must be paid with US funds payable at a US bank or postal money order payable in US Dollars.Electronic subscriptions are US$15/year, and delivery is made in Adobe Acrobat format through Electronic Mail. Allsubscription funds must be made payable to JUAN JIMENEZ, PO Box 155293, Ft Worth TX 76155-0293, USA. To contact usby email, write to flybd5@hotmail.com or visit the BD-5 Web Site at http://www.bd5.com

Late Breaking News! US Govt Awards Free GPS Upgrades Worldwide!

As we went to print, we were advised of some great news for GPS owners. The U.S. government has decided to give theentire planet a free GPS upgrade by removing the Selective Availability (SA) block. This blocking prevented GPS unitsto pinpoint their locations up to ten times more accurately. The removal of SA became effective on May 1, 2000.

The Interagency GPS Executive Board has published the announcement, along with supporting documents and graphs, onits web site, located at HTTP://WWW.IGEB.GOV.

Dr. Dennis G. Milbert, Chief Geodesist at the National Geodetic Survey, explains in one of the documents available onthe web site that to understand the implications of the removal of SA from the worldwide GPS network, you must“… consider a football stadium. With SA activated, you really only know if you are on the field or in the stands at thatfootball stadium; with SA switched off, you know which yard marker you are standing on.”

As part of the announcement, President Bill Clinton’s statement reads: “The decision to discontinue SA is the latestmeasure in an on-going effort to make GPS more responsive to civil and commercial users worldwide. Last year, VicePresident Gore announced our plans to modernize GPS by adding two new civilian signals to enhance the civil andcommercial service. This initiative is on-track and the budget further advances modernization by incorporating some ofthe new features on up to eighteen additional satellites that are already awaiting launch or are in production. We willcontinue to provide all of these capabilities to worldwide users free of charge.“ Enjoy your free GPS upgrade, folks!

January - March 2000

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