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Reduced wing angle of incidence project


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Guest TOSGcentral

No I am afraid things ground to halt under personal pressure.


I was all ready to go (as I previously announced) and then my mother had to go in for major arterial surgery that was a bit touch and go. Queensland Health then proceeded to paralyse me for two months dithering about when to do it. I could make no plans at all because the chance of death was too high.


That was all a flop and they could not finish the operation and she celebrated by having a major stroke a week after the surgery that has half paralysed her. So I have spent the past five weeks mostly away from home remodelling her house to take a wheel chair.


Lois, who lives with us now and owns 381, fell ill and ended up in hospital. I have currently got her convalescing with relatives in NSW but will not start tearing the aircraft apart without her being around as she wants to be fully involved.


On top of that Jesse (Rusty’s wife) had a relapse so I also still have not got the Bilby to Watts yet!


But wait there is more! I got the BMW T500 home just in time for the owner (in Zambia) to have a major car crash and I am still waiting to hear from him so I can get on with that as well!


I have not been a happy camper especially as I also got flu and I am seldom ill normally.


The state of play currently is:


Everything is lined up ready to roll.


The wing incidence bracket is the top priority on the Swift conversion.


My mother is now home (last week) and the situation is stable so I am freed up.


Lois will be back a week today.


Jesse I still have to contact and then fly the Bilby over.


The BMW T500 is on hold until I hear from the owner.


I am NOT going to kill any more Chinamen – don’t think there are any left!


The next TOSG Bulletin will be published in two weeks and out a week later.


Basically the situation is normal – SNAFU! But it could be worse. I do not see how but doubtless I am about to find out!







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Guest TOSGcentral

Hi Deon,


You should be able to get them easily enough at any large building supply oufit - taking an example with you helps.


Alternatively ring Wayne Fisher on 02 6622 4466 and he may be able to help.


The caps do actually have a valid function. They keep the inside of the tubes from getting dirty, they prevent instances such as 6' of brown snake having a kip in a wing spar which happened to one of our membes. They also assist in weight and balance such as avoiding a 3' long rats nest in a wing spar that I took out of a Glasshouse that had been standing in a barn for a while





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  • 2 months later...
Guest TOSGcentral

OK. There is a bit of geometry involved here as the original fitting is all one piece. You cannot simply lower it because it would splay the front A frame – and that would domino into the pod holes and the windscreen fittings.


The existing model of the new fitting is in several parts and bolts together very much like the T600 front fitting. This is designed to get around the splay challenge but also impacts on future servicing. Owners will be able to get the fitting in and out very easily without the usual drama of having to also work on the cockpit front A frame and the domino effect from that.


However it is not simply a case of lowering the leading edge because the existing lift struts will then twist the wing – so they have to be shortened and the whole process is going to take a lot of accurate measurement to get it right so the wing wash out/wash in is not disturbed.


I am planning on the whole thing being inexpensive, backed by full fitting notes, some kind of flight report, and able to be done at home with simple hand tools.


I apologise for this all taking so long but I am starting to get my life back and I do all of this on a voluntary basis out of my own pocket - I no longer run a business.





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Guest TOSGcentral

Hi and thanks for the kind offer.


The situation is not just one of money holding things up (I think I have that under control reasonably well - I have virtually zero personal money but am not a bad manager). It is more a question of time and co-ordination as there are too many factors involved and I have not been able to really predict for months what I would be doing in only a couple of days time.


A big hold-up has been Jesse. Rusty's death really knocked her about so I still have not in fact yet got the prototype model from her. But Jesse is now getting better and I am getting more confident that things will at last get rolling.


I am afraid that appealing to the Thruster owners does not work. I have tried it in the past and did not get a single offer.


A problem is that people are not actually interested unless they need something, and that is understandable.


As examples: I had the three main boom brackets certified in chromally as the stainless ones appeared to be cracking too often from the reports that I was getting. I did not sell a single one and the prototypes went on my own T500.


I did better with the wing strut/spar fittings but only sold 10 sets and have not yet broken even on the cost of the engineering - but someone had to come up with an answer to a Coroner grounding the entire Thruster fleet in consequence of just a single instance of poor maintenance and inspection.


The pods and moulds I obtained with a lot of kindness from Wally Rudin and some horse dealing in trade-offs, but at least they are now secure and available.


Failure of a factory to continue supporting a type is a very serious business indeed. The UK Thruster factory has changed hands and is having desperate trouble for over a year now in getting new approvals from the authorities. Already UK schools are buying different types!


TOSG has helped greatly in Oz to maintain support and most things can now be legally covered.


The Vision 600s went the same way. I am working with Wade and Greg Mahlo on trying to get that going again. In addition I am working up a design where a V600N (Nosewheel version) can be converted to a V600T (taildragger), or back again, with an hours work.


That would give a new lease of life to flying schools supporting traditonal ultralights as they could effectively have two aircraft markets covered for the price of a single aircraft.


The Swift project would not just give schools and private owners a viable alternative to $100k plus machines for about $25k - $30k but ensure that they can maintain the aircraft sensibly themselves yet have all the systems and appointments at a certified 400kg MTOW. In addition owners of existing Thrusters will be able to get a whole range of certified retro-fit options to improve their machines.


The BMW project will give us a reliable four stroke that has had years of proving. The single existing example (A T500 currently in my workshop) has done 300 hours fault free flying and goes like a striped ape! I intend that owners will be able to get the engine, mounts, dual ignition and a full kit with fitting instructions for less price than just an R912 or J2200 bare engine.


There are lots of things to do and they are all valuable to mainstream traditional ultralight flying that is safe and affordable - yet will give the Thrusters a vast improvement on their effectiveness as trainers.


But I am only one person! I already own both the Thruster single and two seat prototypes, a second Glasshouse, shares in a third, all that is left of the T100 prototype and a half share in a T300 that it looks as though I will be taking over completely.


My biggest asset however is a very understanding wife!


It was just unfortunate that this year, when I had so much planned and ready to go, that I ran into the biggest personal problems I have ever had to face. I am getting over it and expect to live for a bit longer yet - so it will happen!







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By reducing the AOI would mean coming in at a higher angle with respect to the boom and the possibility of the tail wheel making contact first? [considering 55knts approach speed]or would the approach speed need to be higher and come in flatter at the flair? Cheers



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Guest TOSGcentral

No! - In practical terms you should not see any difference in handling the aircraft, it will just be easier to land and have less tendency to bounce.


Four degree reduction in AoI (which is what is intended) will not make that much difference to the visual attitude and will have no impact on airspeed at all - far less than doing a fully flapped landing for example>


Your principles are exactly right T87 but your description exaggerates what is intended to happen.


Just to go through it again - the basic problem with the Thrusters is the AoI is too high so as the aircraft goes through the flare and is held off towards the three point landing attitude the wing reaches the stalling angle with the tail still well clear of the ground.


This makes for an untidy arrival with some thumping of the tailwheel - which we would like to avoid to reduce airframe wear and tear as well.


Now, the whole situation is further irritated (and this is the main cause of the drama) because the low speed side of the total drag curve is so steep on the Thruster that drag (and therefore sink) escalates very rapidly as you approach the stall (which is what you are doing in a 3 point landing).


In turn this results in the stick having to come back increasingly rapidly and this is (a) something anyone has to remain very current on to get consistently reasonable landings, and (b) is difficult to teach to students without a considerable amount of depressing bouncing that also knocks the airframe about (especially the all alloy Geminis). That latter condition may be also expressed by saying that the pilot does not have full control of the aircraft's vertical speed when it hits the ground.


The general tendency is to let the aircraft on early and prior to the stall. The tail is therefore even higher and there is ample space for the tail to rotate down with the aircraft still at some flying speed. With the tail pitching down the AoA increases and it lifts off again (bounces) and this is where all the savage bouncing comes from.


OK - so what we are going to do is take sufficient angle off the AoI that when the wing stalls during the hold-off the aircraft will have naturally adopted an attitude relative to the ground where all three wheels arrive at the same time. In this situation the tail cannot go down and increase the AoA because it is already on the ground!


This does not mean that the Thruster can then not be made to bounce - any taildragger will bounce if you let it on too early with too much vertical speed.


The whole situation can be avoided very simply by wheel landing the aircraft and there is no drama at all!


To get into a few wrinkles: No T87 there will be no chance of the Thruster arriving tailwheel first if we get the AoI correct. You are quite correct in that this could happen if we reduced the AoI too much.


A good example is the Ka7 and ASK13 training gliders. They have a shallow AoI (to give them less profile drag and therefore a better glide when at higher speeds) and if you hold one of those off too high then indeed you can have the tailskid on the ground with the mainwheel still about 2' in the air! A good landing on one of these is in fact a tailskid arrival a fraction of a second prior to mainwheel contact - and you cannot get a better landing than that. On the other hand they have immensely strong back ends and are very difficult to damage or cause fatigue wear in that area.


I am not expecting too much drama with the mechanical adjustment (once I can get on with it) but of more concern to me is the flapperon system that will be fitted.


The new bracket will resolve most of the landing problems for conventional Thrusters (as much as is practical on a full blooded taildragger anyway) but the Thruster Swift will have a certified flapperon system on it.


Flapperons change the mean chord line of the wing so INCREASE the AoI in positive flap settings and will make the fully held off landing even more difficult if just fitted to a conventional Thruster. The new AoI bracket will also tame that quite a bit and the condition can be anyway avoided via the wheel landing technique as your landing speed is down by about 6-7 knots on even quite a heavy Thruster.


This is why I have to do a couple more hours test flying in the Bilby to fully examine its flapperon system in conjunction with its already reduced AoI. From that I can then ensure that what goes on the Swift is the best possible angle and produce a full set of flap handling notes for new owners to go along with the fitting notes that will come with the flapperon kit.


Apologies if this has sounded a bit convoluted or technical but the end result is that the Thruster will just be an easier aircraft to handle for the average pilot and a lot less depressing as a trainer to the average student - and that is what I am primarily after without them necessarily knowing "why it is so" if they are not interested in aerodynamics.







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  • 2 weeks later...

Aha ,


My third post , I'm getting the hang of it now.




Are you aware of any flaperon retrofits in Oz? , they seem to be popular in NZ?


My interest in flaperons is more to do with setting them in reflex mode for cruising flight.


I don't think I need any more lift during takeoff or landing, although flaps should promote a better attitude during landing.


Incidentally I always three-point, and haven't noticed any bouncing tendency, although I do tend to bounce when doing wheelers though. Pervesely though , I tend to prefer tail high taxiing (but not downwind ). I have the big soft springs, so I think the main gear touches slightly before the tail wheel, but then flexes up under the weight, so you are actually in the three-point position with the undercarriage deflected.


I had read about the reducing angle of incidence project, and wondered what the motivation was, thanks for providing some illumination. Possibly the lowered incidence angle will improve the ground handling and minimise the inadvertent departure from the ground in gusts.


Cheers, BobT



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Hi Bob, Welcome to this forum,I like the look of your thruster, How about some pics and back ground. Have you had her long, what else do you fly, how long you been flying, why choose a thruster. it's too windy to fly in tassie at the moment so I'm bored.



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Hi Terry ,


Coincidentally I was looking at the pictures of your Thruster, just now. Its nice, I like the fairings, something I always wanted to do, I wanted to put landing lights in the fairings too, (landing in the dark by feel is vastly over-rated).


I did some Cessna type training (to solo stage) about 30 yrs ago then it kind of lapsed.


I originally bought a broken trike, and then a replacement wing for it, did some trike lessons, discovered it wasn't really my cup of tea, and gave up on the trike thing, but still kept tabs with the trike crowd.


I think I fell in love with a Thruster that was fundraising for red nose by flying from Sydney KSA to Tasmania around 1993. The local instructor, Keith, also had a red thruster, which I trained on. I bought a second hand T500 that was vaguely flyable from the factory. Then stripped it down, reskinned it, painted the pod , redid the control panel added a transponder, added GPS, Added doors (only used for cross country, stop the maps flying out the window, I don't actually like having the doors on) added spats (from an edge trike, they make them here in Newcastle). Then I painted the nose red and flew with another 5 guys around Queensland fund raising for Red Nose in ~1995. Great Times!, the trip was supposed to end at Watts Bridge , which we were really looking forward to, but the weather clagged in , and we stayed in Noosa until the weather cleared.


Somewhere along the way I got my PPL , just a formality really, as once you can fly a thruster you can fly anything. But you do get more respect from the spam cans when you talk like a real pilot. I nearly got an IFR rating , but failed the theory. Did 3 or so flying safaris in C172's and C182's with the guys from work.


It was hangared at Cooranbong, but it closed 2 years ago, so it was put on a trailer and parked in my shed, it's still there :<(


I will be semi retired in 8 months so I will fix it up then, and get it back into the air.


Cheers, BobT



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Hi Bob, I know Cooranbong well because my son is doing a science degree at Avondale college. Look forward to some pictures of her some time


Regards Terry



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Guest TOSGcentral

Reply to T-Bob.


Yes Bob, there are flapperon fitted Thrusters flying in Oz. I have flown both single and two seat versions with flapperons - the Bilby for example has them. But flapperons have not yet been 95.25 certified in Oz.


NZ does have them certified (I have a copy of the original certification which was done from no more than a sketch).


To my knowledge no reflex flap setting have been yet used. The Kiwis basically wanted the low speed landing and take off end for the confined areas in which the aircraft are operated.


I do want the the reflex flap for improved cruise via reducing the profile drag - I feel that alone could give us another 5 knots. Equally I want the low speed end as well for confined space operation on a much heavier aircraft. So that is one of the "Swift" projects that I am currently working on.







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