nasa facts lifting bodies

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PageFA ( TSNASA FACTS Vol. IV,.No. 2

An Educational Services Publication of theNational Aeronautics and Space Administration

LIFTING BODIES

(THRUIIACCESSlyN U M B E R )(PAGES) L /

( NA S A CR OR TM X OR A D NUM B E R)(CATEGORY)

Clole-up view of th e M2-F2, a "lifting body."

How can you bring a manned spacecraft backinto the atmosphere from orbit, have it withstandthe inferno of reentry and permit the pilot tomaneuver over a wide area as he selects andtouches down at the ground landing site thatsuits him best?

The National Aeronautics and Space Administration believes the answe r may be to use"lifting-body." Reentry and recovery of mannespacecraft in the Mercury, Gemini and Apollprograms of NASA have required parachute systems for deceleration and letdown, and the pos


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c , ~ - d - (; .7 NASA FACTS Vol. IV, No.2tioning of recovery ships across wide expansesof the oceans.

How much simpler it would be i f a returningmanned spacecraft could penetrate the atmosphere and glide to a landing like a conventionalaircraft.

Such is the prospect raised by lifting-body re-search. Persons associated with the effortenvision a variety of future missions in space fo radvanced versions of these unusual craft.

l i ft ing bodies are wingless vehicles that obtain aerodynamic l i f t-essential to fl ight in theatmosphere-from their shape alone. Additionof tw o or three fins provides the stability re-quired for pilot control.

NASA is exploring and evaluating the potent ial of these l i f t ing body concepts in a fl ightresearch program that evolved from earlier windtunnel and theoretical studies. The overall lifting body program is the responsibility of NASA'sOffice of Advanced Research and Technology.

The aerodynamic advantages of lifting bodiesover manned reentry vehicles in present use, thelow-speed handling and landing capabilitiesdemonstrated early in the fl ight test program,and the emerging potential future uses fo r liftingbodies combine to make this a highly promisingarea of advanced research.

l i f t ing bodies provide greater l ift and higherlift-to-drag ratios than present manned reentryspacecraft. The Mercury, Gemini and Apollocapsules follow a ballistic-type trajectory (like aprojectile or missile) on reentering the atmosphere. Once committed by retro-fire, the astro-nauts had limited control over the subsequentfl ight path. Changes in the touchdown pointranging to about 40 miles were the most theycould achieve.

However, as manned spacecraft becomelarger and heavier, their missions more complexand far-ranging, space pilots will require increas-ing authority in the decision fo r landing siteselection. This does not mean necessarily thatsome future space pilot returning to earth willbe able to choose anyone of the 6,000 airportsdotting the U.S. landscape, but it does mean thathe will be able to exercise some latitude should

it become necessary to choose between availablelanding sites.

Theoretical studies and tests of l ift ing bodyconcepts began in the United States in the early1950's. Combined research efforts soon cen-tered on a number of half-cone shapes thatpromised to provide adequate l i f t for aerodynamic flight.

In 1957, the idea of adapting these half-coneconfigurations to a manned vehicle capable oforbiting and reentering the earth's atmospherewas developed by NASA. The problem was todesign a craft suited to rocket vehicle requirements and also one that would be aerodynamically stable, and maneuverable from hypersonic(above 3,300 miles per hour) to subsonicspeeds and be capable of horizontal landings.

To reduce heating resulting from high-speedentry from space into earth's atmosphere, thenose of the "cone" was blunted. Fins were in-stalled to provide stability and control surfaceswere added for maneuverability .

Design innovations had to be built into liftingbodies to accommodate the transitional areasbetween space and atmospheric fl ight and,within the atmosphere, hypersonic, supersonicand subsonic flight. Conditions vary for eachflight regime.The fact that lifting bodies have no wingseliminates many possible problems in structuresand reentry heating. However, the necessityfor flight at hypersonic, supersonic, and subsonicspeeds challenges designers to find the compromises that will accommodate al l of these speedlevels and conditions.

NASA wind-tunnel studies, corroborated bytheoretical engineering analysis, have indicatedthat a l i fting body can generate enough l i ft topermit a pilot returning from a space f l ight toselect his landing site.

How precise the initial choice might be woulddepend upon just when the landing selection wasmade. For example, from fa r ou t in space onlya hemispheric selection would need to be made.If the Western Hemisphere were chosen then, asthe craft neared earth, an area encompassingthe southern section of the United States mightbe selected. Then, as velocity and altitude


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NASA FACTS Vol. IV - No.2 PageMilton Thompson, National Aeronautics and Space Administration research pilot wh o heads the joint NASA-U.S. Air Forceteam testing th e M2-F2 lifting body research vehicle, tries out the craft 's cockpit. Test flights are expected to demonstrotehow lifting body space vehicles would behave In th e earth 's atmosphere during th e period between reentry and landings.


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Page 4d i m i ~ i s h e d , final determination of actual touchdown point would be made. local weatherconditions, visibility, runway lengths, and airtraffic congestion are factors that might enterthese determinations.

Based on research work conducted at theAmes Research Center, Moffett Field, California,and at the Langley Research Center, Hampton,Virginia, two separate lifting body designsevolved and were proposed for flight investigation.

The first lifting body to be flight-tested byNASA Flight Research Center, Edwards, California, was called the M2-F 1. It was simplyand inexpensively constructed of plywood andtubular steel. Towed aloft by an aircraft, it wasreleased at about 10,000 feet to glide to a controlled landing. The M2-F I , during its morethan 100 flights, confirmed the feasibility of con-

NASA FACTS Vol. IV, No.2trolling lifting bodies during the critical landingphase of flight.

The success of these tests led to a contract toprivate industry in 1964 for the construction oftwo heavyweight test vehicles designated theM2-F2 and HL-10. The M2-F2 was deliveredto NASA in mid- 1965, and HL- 10 in early 1966.

The M in th e designation M2-F2 refers to"Manned" and the F to "Flight" version. The2 refers to the second modification of the basicM2 shape. HL refers to "Horizontal landing"and the number 10 means that it is the tenthlifting body model to be investigated at Langley.

Both vehicles are 22 feet long, but the HL-l 0stands about two feet higher and five-and-onehalf feet wider than the M2, for added stability.The controls of the two craft are quite different,to test two different control techniques.

NASA', M2-F2 Lifting aody Is shown mated to the a -52 launch aircraft at NASA's Flight Research Center , Edwards, California . Th. two vehlc l .s were joined together to eva lua t . their compatibility, systems checkout, and to perform certa in . t ructural t e . t . . NASA I. using the vehicle to s tudy th e lifting body concept for possible u a , a spacecraf t ofth e future tha t would be capabl . of re.nterlng from space and landing on earth under pilot control.


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- ...NASA FACTS Vol. IV, No.2 Page 5

Artist 's conception shows NASA's HL-l0 lifting body vehkle being dropped from a 8-52 mother ship. Th e HL-l0 , aNASA Langley Research Center configurat ion, Is being designed and fabricated by Northrop Corporation. Note th eadapter that allows th e HL- 1 0 to be carried under an X-15 pylon.

The M2-F2 is flat on top and rounded on thebottom. The HL-l 0 is exactly the opposite andmore of a delta-wing shape. Only the M2-F2has a bubble-type cockpit canopy that protrudesabove its flat top surface. Both have roundedwindows in the nose for better pilot visibility.

Both vehicles weigh about 5,000 pounds or9,000 pounds with water ballast tanks full.Small, throttlable hydrogen-peroxide rockets areinstalled on the rear of each to give the pilot upto about 1000 pounds of thrust, providingadded velocity if he needs it, during the landingflareout and approach.

For the flight tests, the lifting body is carriedbeneath the wing of a B-52 to an altitude ofabout 45,000 feet. Then it is released andglides to a landing on Rogers Dry Lake, California. The research pilots perform various ma-

neuvers and tests designed to develop pilotingtechniques an d to evaluate control systems andhandling characteristics.

Both the M2-F2 and HL- 10 are designed toaccommodate rocket engines for powered flightat a later phase in the research program.

Duration of the early, unpowered drop-andglide flights from launch to landing is approximately four minutes. They can be launched atspeeds up to about 530 miles per hour. Landing speed, depending on the flight mission, canvary between 160 and 240 miles per hour.

Later, depending upon the nature of the continuing flight research program, XLR-11 rocketengines, used at one time to power th e X-15high-altitude research plane, may be installedaboard each of the two research spacecraft.This will permit flights at higher velocities and


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NASA FACTS Vol. IV, No.2

Artist 's conception shows NASA's M -2 lifting body vehicle landing a t NASA Flight Research Center, Edwards, California. ItIs based on a configuration developed by the Ames Research Center. After thorough testing and evaluation both the M-2and HL-10 are to be investigated in flight a t Edwards. They are carried aloft by a 8-52 car r i e r - in a manner similar tothe X-15 - and released at 45,000 feet . Th e pilot then glides th e craft into a landing on Rogers Dr y Lake a t Edwards.

altitudes that more closely approximate the con-ditions of a spacecraft returning from orbit.

Operationally, this type of craft, with the ca-pability of operating in and out of the atmosphere, may prove extremely useful for a numberof space missions. These may include orbitingspacecraft inspection, space satellite repair,logistic support and resupply of earth-orbitingmanned space stations, space search and rescue,or possibly as a recoverable upper stage of alaunch vehicle.

At this time no mission or research plan hasbeen determined by NASA for the design or con-struction of an actual space flight vehicle, but theresearch must be performed well in advance topermit freedom of choice if such a program be-comes necessary.

FLIGHT RESEARCH PROGRAMThe first free glide flight of the M2-F2 was

made July 12 , 1966, with Milton O. Thompsonas pilot. It lasted about 4 minutes an d wascompletely successful.

As with the X-15 research program, a finalgo-no-go checkout and countdown is conductedwhile the lifting body is being borne aloft underthe wing of the B-52. The checkout is handledin this manner so that if any weather or technicalproblems arise during the last few moments theglide flight can be cancelled.

Prior to the first free flight of the M2-F2, captive flights and ground runs were made. Thefirst captive flight, with the craft remaining lockedto the 8-52, was made March 23, 1966. Acomplete systems checkout was made in flightwith the B-52 and the manned M2-F2.


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NASA FACTS Vol. IV, No. 2 Page

, ' M-2 LIFTING BODY RESEARCH VEHICLE

LENGTH:WIDTH:HEIGHT:MINIMUMWEIGHT:MAXIMUMWEIGHT:CONTROLS:

BALLAST TANK FWD.

UPPER FLAP ACTUATORS

B-52 ATTACH FITT INGS (2) OUTBD.

POWER SOURCE BATTERIES

SPECIFICATIONS AND COMPARISONSOF THE M2-F2 AND HL-l0M2-F2

22 feet, 2 inches (nose ti p to tipsof backswept tail fins)9 feet, 7 inches (extreme rear ofvehicle)8 feet, 10 inches (ground to top offins)5,000 pounds (with water ballasttest tanks empty)9,000 pounds (water ballast tanksfull for tests)A rudder on the outer face of eachfin for yaw (lateral movement backand forth) control. Upper flaps forroll (corkscrew action) control an dpitch (nose up-nose down) trim.One full length pitch flap on lowersurfaces of th e tail.

HL-l0Same15 feet, 1 inch (including tips offins)11 feet, 5 inches (ground to top ofcenter fin)5,265 pounds (with water ballasttest tanks empty)SameA thick "elevon" between each finan d the center fin for pitch an d rollcontrol. A split rudder on the cen-te r fin fo r yaw and speed brakecontrol. Each elevon has a flap onthe upper surface, each outer finhas tw o trailing edge surfaces.


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