Sonex in Europe

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Newsletter 13, February 2016

Sonex LLC have no part in the production of this newsletter, its contents are solely the responsibility of the author.

Rotax 912 powered Sonex recently spotted in Portugal. Prop clearance looks like ground operations might be

interesting!

Welcome to the 13th Sonex in Europe newsletter. Not sure

where all the time went from # 1, here we are at # 13!

Second generation Sonexs!

You’ll probably have seen the announcement from OSH about the new ‘B’ models, or

‘widebody’ versions perhaps. All very interesting, especially the new engine options. Both Rotax

and UL are European organisations so sourcing one for build here now much easier. It will

remain to be seen of course whether LAA Engineering will accept either the new fuselage or

engine options for British builds, but you lucky Europeans will be able to look at much wider

engine options now. Looking at the Rotax Sonex in the pictures above I wonder how they’ll deal

with getting a large enough prop on a [?] ‘Ronex’ whilst retaining sufficient ground clearance.

The rearward movement of the seatback could raise eyebrows at the LAA too, as rearward CofG

movement would not be popular.

Looking at the pictures on the Sonex website suggests that retrofitting a ‘slimline’ Sonex won’t

be possible as it looks like the engine mounts are as wide as the new forward fuselage width.

A possible aerodynamic effect is that there is the chance that reducing the angle at the

forward/aft fuselage junction will reduce drag somewhat, though whether that would be

quantifiable is unclear, and might be offset by the slightly larger frontal area.

As I write this the weather is poor, not VFR flyable, and has been for what seems like many

months. I’m still working on completing John Dilk’s flying programme in GCIDX for Permit

issue, hopefully we’ll get that done soon and John off enjoying the results of all his hard work.

I’m just back from 3 weeks in New Zealand where the weather, high summer there of course,

was fantastic….but I had no aircraft to fly. I tried contacting a Sonex flyer in Whangerai, but no

answer. Now I’m back to cold, wet and windy, but it must improve sometime. No excuse for not

getting out into the garage and trying, again, to get the upper forward cross tie in place so I can

get the lower firewall fitted.

Sonex exposure at the LAA Rally last year was great, displaying my part completed fuselage, tail

feathers, and one wing engendered great interest, however I won’t be able to repeat the exercise

this next Rally as I failed to get Leave from work to cover the necessary days. I have got a single

day off on the Saturday of the Rally, the 3rd September, and plan to fly in courtesy of an old Jodel

I fly from Wellesbourne airfield. So I propose that we try and have our becoming traditional ‘get

together’ that afternoon, around as many Sonex aircraft as can fly in. I’ll arrange to get all Sonex

aircraft parked together and we can meet, mingle and chat around them. Further details closer to

the time, but please make a note now of the date, and plan to be there. We could get 10 or more

Sonexs together weather and your availability permitting.

A great newsletter this time [IMHO!] mainly because I’ve received significant stuff from

members about what they’re doing etc.

News from Mike Moulai and Silverfern

Mike was unable to get a full report to me before he too set off for a visit home to NZ, but he’s

settled in at the new premises in Yorkshire, is test flying an Aeronca Chief there fitted with a

very interesting Verner radial engine.

The first Onex kit for the UK has arrived, together with lots of other stuff….including my

AeroVee kit. Mike assembled the Onex fuselage in 24 hours, firewall to sternpost, thanks to the

accuracy of the pre drilled parts.

He’s working on the aerobatics and SubSonex approval situation, and has achieved significant

publicity for matters Sonex recently, which will greatly help us in spreading the word this side of

the Atlantic. This includes tempting LAA members with a bit in this month’s ‘Light Aviation’

about the Onex and SubSonex being considered for approval, and the wider light aircraft

fraternity with a flight test of the SubSonex in ‘Flyer’ magazine, complete with full colour front

cover picture.

Chris Rayner’s Jabiru engine course report

Chris, owner of GSONX, writes of his Jabiru/Camit engine education last November:

Jabiru/CAMIT engine course at Southery, 14th November 2015.

Roger Lewis had a stand under the CAMIT banner at this year’s LAA rally and I had a question for him

about my Jabiru 3300A engine. I asked him what is the correct quantity of oil to put in the sump to

prevent the excess being blown out of the breather and coating the underside of my Sonex. In the

course of our chat, Roger mentioned that he was thinking of running a technical course for the

Jabiru range of engines if there was enough interest. Clearly there was, because a few weeks later a

date was announced and I put my name down.

The course was run at David Burnett’s private airstrip in Southery, East Anglia and was a double act

from 9 to 5 with the “luxury” version which included tea, coffee, biscuits and a very enjoyable and

filling 3-course lunch, included in the £105 fee. The standard version saved £10 but the extra was

very much worth it.

Attendees were mostly from the micro-light fraternity (including Waiex builder and Kolb flyer Stuart

Garton) who uses the 4-cylinder Jab, but I believe will have a CAMIT 3300 in the new aircraft

(especially after the course!).

Roger (mostly) and David talked about the development of the Jabiru engines, the various versions

and their shortcomings and the ways to overcome them or at least to spot problems when (or

preferably before) they occur.

The engines do seem to suffer from the common problem associated with small production

volumes, of manufacturers using the customers to trouble-shoot and develop the product.

Unfortunately though, to quote from the presentations, changes have often been made to correct

symptoms rather than the underlying problems. I can’t go through all the instances that were

discussed (you’d be better to go on the course for that) but there are a few issues that are worth

mentioning which are applicable to all versions and should be checked.

Rotor arms: the only really reliable rotor arms are those made by Bosch. They (unfortunately) are

not so easy to find these days but I believe can still be obtained through Roger, e-mail

powengcon@gmail.com . Even Jabiru has been supplying lower quality alternatives which have

(allegedly) caused some well publicised problems. The things to check for are: the rotor arm is tight

on its shaft (dust in the distributor cap indicates a wearing rotor arm); oil in the distributor (the oil

seal is worn); the carbon brush moves easily against the spring.

Electronic ignition coils/triggers: if these are not set with the correct gap between the coil and the

flywheel magnets, they can overheat, distorting the thin plates and possibly causing the ignition to

fail.

Cylinder head torque: this should be 24 ft lbs in old money and the hex head bolts can loosen with

time/use. This will cause exhaust gas to escape between the head and cylinders (visible as dark

marks above where the push rod tubes enter the heads) and can eventually cause the cylinder heads

to distort. This is important to check, especially of you have bought a second hand engine, or haven’t

done so for 50 hours or a year or so. The bolts are 1/4” hex drive and access to the lower one on

each head is by removing a tapered grub screw in between the rocker arms. I have checked mine

since attending the course. My engine has done about 130 hours from new and may not have been

checked before, but about half of the bolts needed tightening(!) and several cylinder heads had the

tell-tale black scorch marks.

Temperatures and oil pressure: both are critical, but unfortunately readings from both the standard

senders and hence instruments can be misleading! The pressure is normally measured before the oil

filter/cooler adapter but it is the gallery where it should be measured as it is possible to have good

pressure showing on the gauge, but (and I did get a bit lost here) poor pressure going to the bearings

etc. Also, the pressure should definitely drop at low revs when the oil is hot, otherwise the pressure

relief valve can allow the oil to bypass the bearings and so cause reduced lubrication. Regarding the

oil temperature, once again it is important to see at least 90C sometimes, especially when the

engine is working hard (eg on climb out). If the temperature is always lower than this, either the

engine is being overcooled or the splash lubrication which helps cool the pistons is not effective

(possibly due to low oil pressure) and this can cause the cylinders and heads to overheat. Fitting a

Thermostatic Oil Cooler Adapter (TOCA, as made and sold by Sonex builder, Steve Rance) is an

excellent idea and should go at least some way to solve the temp/pressure issues.

Condensation: this is related to oil temperature, but also can be the result of lack of use during cool

and damp weather. The Jabiru engines are very sensitive and two engineers on the course who

service them agreed that perhaps 50% of the problems they see are due to corrosion caused by

condensation. In cool, damp weather (eg UK winters, or maybe even summers) the engines should

be run, or at least turned every 2 weeks or so. If run, it is important that the oil reaches full

operating temperature, otherwise the internal condensation will not be removed. Alternatively of

course, the engines can be sealed and inhibited for the duration. Flying regularly seems the best bet

to me – even in winter! When checking the cylinder heads torques I did notice some condensation in

#1 cylinder rocker cover, but no consequent corrosion.

Hydraulic lifters: this was a disappointment to me. My engine has them and they are successfully

used by other aircraft and car engine manufacturers. However, they can be problematic on the

Jabiru and it seems the solid lifters and manually adjusted rockers are the most reliable. However, if

you have the hydraulic lifters, there is not much choice but to stick with them and keep an eye (or

ear) on them or get them changed for solid lifters. This is not particularly difficult but is expensive of

course.

CAMIT: the majority of the engine is made for Jabiru by CAMIT and due to some marketing

arrangement, CAMIT have been able to develop and market their own versions of the 4 and 6

cylinder engines. They claim to have solved most (if not all) of the known problems with the engines.

Many (but not all) of the parts are interchangeable and apparently the most significant improvement

is to change to the CAMIT cylinder heads - once again, an expensive option.

In summary: the Jabiru engines can be smooth, reliable long-term performers and rarely “let go” or

stop without warning. It is especially important to treat the engines properly and service them

regularly and carefully. In this respect, they are no different from any other aviation engine that you

are trusting yourself with. If your engine is performing satisfactorily, there is probably no reason to

change anything, just be assiduous with its care. To me, the course was very much a case of

“ignorance has previously been bliss”. With cars, that really isn’t much of a problem, but aircraft are

a whole different ball game and I am delighted to have had my eyes opened – at least partly. This

precis is just my inexpert interpretation of the day’s content, so must be read with that in mind. I

have no hesitation in recommending the course if you want to know more about your own

“donkey”. I gave Roger’s e-mail address above, and I hope David doesn’t mind me giving his phone

number if you wish to enquire about future courses – it is 01366 377005. Attendance also qualifies

for a tick in the new LAA Wings Awards box, if you want to work towards one of the little badges.

The oil quantity: well my course attendance happened because I asked about how to stop the oil

blowing out of the breather on my engine. I didn’t get a definitive answer! It could be excess cylinder

gas blow-by – caused by cylinder corrosion. Or, after an oil change, I could put the suggested 3.5

litres of oil in the sump (including the filter quantity) and then run the engine until oil stops coming

out of the breather and check what level is showing on the dip-stick. Assuming it is not caused by

excess blow-by, I should find the correct quantity for my engine……

Sonex trailer for sale

Paul Askew has a trailer he had built specifically for his Sonex GCGPU for sale. It is located near

Blackpool, north west England, and he is asking £500. I had an idea to buy it myself and make it

available as a Group resource, but sadly I have nowhere to store it, nor a car able to tow it. Paul

is at paul.askew@edf-energy.com

Craig Miller’s Sonex GCIDP

Craig’s account of getting his aircraft from kit to flying, much quicker than me! I tried to import

some pictures from Flickr, with no success, I suspect some form of copyright stopping copy and

paste, but there’s a link at the end of the article to his account where there are many great

photos.

My aircraft is a standard gear AeroVee powered Sonex with a fairly basic steam gauge

panel. It flew for the first time from Goodwood on 10 October 2015 under the control of test

pilot Adrian Brook. Adrian is also the project inspector and has been invaluable in doing all

inspections from the kit arrival to flying the test programme. Since the first flight the aircraft

has flown another few times until the airfield became too much like a swamp to safely

continue with the test programme.

My brother Keith and I began building Sonex 1526 at the beginning of December back in

2011 so it has taken us approximately four years from starting the build to first flight. Keith

has been especially helpful during the build allowing use of his garage and working

constantly with me on every step. Having the two of us working on the build has also helped

avoid mistakes in interpretation of the plans as well as allowing us to divide attention to

different tasks. For example Keith would work on the fuel system while I installed the engine

fence baffle seals.

There have been many challenges throughout the build including what seem to be the

common Sonex issues, such as fitting the cowl and canopy, but also the extra difficulties of

being in the UK such as the LAA requiring initially fitting carb heat. This was fairly expensive

to do but more importantly caused a restriction of airflow to the AeroCarb lowering the

maximum engine RPM to about 3000! This was probably due to our design of carb heat

system but then I do not think it is a great idea for the home builder to redesign the intake

system. Fortunately after a bit of negotiating with the LAA they have decided to allow testing

of the engine without the carb heat system but with the addition of temperature sensors on

the carb body. Hopefully this will result in the removal of the requirement for carb heat on all

AeroVee/AeroCarb aircraft in the UK.

Hopefully testing will resume within the next month as the weather improves into spring.

A selection of pictures can be found here: https://www.flickr.com/photos/96018754@N05/.

Here is a log of the build: http://kdmiller.unospace.net/mediawiki/index.php?title=Main_Page

Steve Rance trim position indicator design

Steve Rance, design engineer and BMAA Inspector, has designed a very neat trim position indicator for the ‘Dial a trim’ system. This allows the position of the system to be shown next to the selector with a simple mechanical setup….picture below. It involves cutting a slot in the side of the drive mount and installing a pin into the central slider which then sticks sideways through the new slot. In turn the pin then moves an indicator up and down, via an articulated cam follower, next to the selector. All will fit under the instrument panel on the sub panel most builders mount.

Steve has sent details to the LAA Engineering department, requesting formal approval as a ‘Modification’ allowable for all UK Sonex aircraft using the ‘Dial a Trim’. That approval is pending. Once all approved Steve has very kindly offered to supply laser cut cam pointers at cost, together with full drawings. The drawing template would allow anyone with suitable equipment to produce their own system too. Steve is at steve-r@ntlworld.com

Dirk Verdonck’s experience building his AeroVee

An excellent article about building the AeroVee kit, and perfect timing for me!

Aerovee 2.1

Hello All,

My name is Dirk Verdonck and I am a Belgian citizen building Sonex Onex s/n 117.

I know there is none of these on the British register yet and the LAA has not yet approved

the design but this should change in the near future as there is apparently someone in

Blythe who will start building a Onex soon.

The Onex is not really relevant here as this short article deals with the assembly of its

engine, the Aerovee 2.1 which is also offered on the Sonex and is also available to any non-

Sonex builder.

The engine comes in 4 boxes which contain all parts, manual and DVD.

First thing I did was going through the manual to understand the build order and view the

DVD, old and new version, to visualise it all before opening one of the boxes.

I have an engineering background and have assembled engines before so there was nothing

really new to this although I never got my hands on a VW flat four.

Something I want to stress before you start a build of an Aerovee, take your time and forget

that you can do it over the weekend. It took me about 50 hrs, not taking into account the

coffee breaks!

After first inspecting the boxes to check if all parts were there, I started cleaning up both

crankcase halves, the castings are not really well finished so I took my time to get the

surfaces nice and smooth, removed all sharp edges and thoroughly cleaned it all with hot

water and soap after which everything was dried with an air hose and hot air blower.

Before painting the crankcase, I installed the camshaft and crankshaft equipped with all four

piston rods to check for interference. As the case is modified and the crankshaft has a longer

throw than the standard one, there is very little margin in some places!

lt was ok and everything was disassembled to prepare the crankcase for painting. I used a

dark grey heat resistant paint which looks better in my opinion than the black paint

suggested in the manual.

Next step was putting the running gear back in place and torque everything to specs whilst

checking free rotation after every step using a piece of wood attached to the prop

hub.(Some of the case studs are a bit short as the nut is level with the stud after tightening).

The four pistons were individually weighed and came in very close, three identical and one 4

grams heavy. (I installed the heavy piston close to the big end side).

After checking the bores with the piston rings, the four cylinders and pistons were installed.

I choose a compression ratio of 1/8 and calculated the number of shims that go under the

cylinder base and will use Premium Autogas. (Pay attention to the arrow on the piston

head!).

After this was done, I started a big job on the cylinder heads. Their castings are also rough

and not very eye pleasing so I spent about 10 hours removing all sharp edges on the cooling

ribs and drilling cooling holes through the heads in between the combustion chambers.

(these are mostly closed as the cast mould doesn’t allow for these narrow air passages).

All valves were removed and the valve seats inspected after which the heads were

thoroughly cleaned before re-assembly. The heads were also pressure checked to be sure

there were no leaking valves.

I installed the heads and determined the lengths of the studs not to interfere with the

rocker shaft and arms, disassembled everything, removed the studs and cut them to the

correct length. Studs back in and cylinders and heads can be installed and torqued as per

manual.

I did not install the push rod tubes at this time as I choose removable ones that are available

from VW on line shops. They consist of 2 concentric tubes that are spring loaded and

equipped with O-rings. They allow for the crankcase and head seals to be replaced without

pulling the heads.

Next was the oil pump that was installed without a paper seal to obtain best oil pressure.

After that the big end oil seal and the flywheel shims got in. I had quite a bit of reaming of

the flywheel holes to do to get it properly seated on the crankshaft. After that, the

backplate equipped with all ignition hardware was attached and finally everything went

onto the engine mount. The high tension coils were attached to a support that is held

between the top engine mount tubes.

With some of the left-overs of the Onex crate, I built a test stand which will allow for the

installation of the prop, wired everything up, installed intake and exhaust pipes and a plastic

bottle that serves as a fuel reservoir.

The spark plugs were then removed and the engine cranked until the oil pressure came up.

Plugs back in, fuel in the orange juice bottle and the beast started up after two attempts!!

I let it only run twice for half a minute without prop not to overheat anything.

I am now waiting for the prop to arrive to make longer ground runs and adjust the settings

of the Aerocarb.

Conclusion: A bit of mechanical fingerspitzengefül is required to assemble the engine but it

is a very satisfying process if it works first time!

I bought all recommended sealing compounds and you should of course have a full set of

metric spanners and sockets and the appropriate torque wrenches.

Mechanical pressure gauge

Take your time and burn a lot of elbow grease and you’ll end up with a nice result. Enjoy!

Well, that must be the biggest newsletter so far, with great, helpful information in it I

believe. That is all down to you, the members who’ve taken a little while to give me their

thoughts and experiences on matters Sonex. If you’ve got some experience, building or

flying, that you think might be of interest to the rest of the Group please let me have it for

the next edition.

As always, if you don’t want to receive this newsletter in the future please write to me and

I’ll take you off the mailing list. Conversely, if you know of anyone who might enjoy reading

it either get them to write to me, or if they’re happy send me their email address.

Safe building and flying,

Steve Moody

Leamington Spa, England, stevemoody04@aol.com

Building Slimline Sonex #1383, tailwheel, lowered seat mod, AeroVee, dual stick.

www.sonexeuro.com