Another one in the Stable

[Deskpilot]

Most of you know that I dabble a bit in aircraft design when I've nothing better to do. Well I thought you might be interested in my thought train in some of these designs. This probably will bore most of you but for those who are still interested in home design, sometimes called dreaming, ..................read on.

 

There come a time in all our lives when we see some thing that really strikes a cord within us. This is generally what sets me off. Years ago I came across the FanTrainer, a small pusher plane that was designed to be a lead in to small jets (click to enlarge)[ATTACH]13000.vB[/ATTACH].This was later redisigned by Colani into the FanLiner, a very nice side by side recreational aircraft [ATTACH]12999.vB[/ATTACH]. I was particularly drawn to the prop position, which, although it has it's draw-backs, I think is the correct place for it to be. We can argue that point at a later date. Anyway, this lead me to thinking and the outcome was the DeMansfield Bolt [ATTACH]12990.vB[/ATTACH] [ATTACH]12991.vB[/ATTACH]

 

After much discussion with some of our American friends, potential problems with rotational harmonics within the boom tube, and the high cost of getting the Prop-assembly made, this design was put on the back shelf for the time being. Maybe I'll resurrect it one day because I still like it for a low and maybe not so slow fun plane.

 

Next I came across John Dykes 4 seat Delta wing, the JD-2..[ATTACH]12998.vB[/ATTACH] I was imediately intrigued by this design, after all, there aren't too many light deltas around, are there? I decided to have a go at creating a fast, single seat version. Something capable of touring. Something that would turn heads. Hence my EagleRay. [ATTACH]12988.vB[/ATTACH] This exercise went on for a considerable time, mainly due to the theory of deltas and the mathematics involved in designing a wing that would actually fly, especially at slow speeds. I found out from John Dyke that he had helped another guy build a similar plane but he was not prepared to help me in any way. I believe his belief is that his original design was the best solution and should not be tampered with in any way, shape or form. Of my other American friends, well they just pointed me to books, most of which would go over my head, if you know what I mean. Another project, not exactly shelved, but certainly on the back burner.

 

Now, I'm a member of Homebuiltairplance.com (HBA) on one of the threads running there was something called the Ring Tail. [ATTACH]12989.vB[/ATTACH] Designed and built by one Mark Stull, this design, which by the way, evolved from a earlier design of his, had many of us intrigued and we followed his thread with great interest. As we talked, I wondered, and suggested that it might be possible to create a Vectored Thrust version by changing from a tractor, to a pusher design. Now I knew that this would be controversial due to the probable problems associated with the gyroscopic effect but that didn't deter me and I modified a copy on my Bolt accordingly [ATTACH]12992.vB[/ATTACH] . A radio controlled model is to be built in the states to evaluate this design. Something I must follow up on.

 

Now, a week or so I received a message from the Dykes Delta Yahoo page referring to a plane that had a sort of delta wing, called the Stinger H_5 [ATTACH]12995.vB[/ATTACH] [ATTACH]12994.vB[/ATTACH] Something caught me eye. I liked it because it was different, but for some reason, I could see the TSR-2 in it. Go figure. I questioned JD about it as he knew the designer and was told that it 'flew but a few times' and inferred that it was unstable. On prodding him a bit more, he said it was because it didn't have elevons as per his design. Hmm, ok John, your right as usual, well at least in your mind. John, btw, is in his eighties and is blunt to say the least. Anyway, I thought I'd have a go at improving it. So where to start. With the TSR-2 of course. A beautiful plane that bygone idiots in the British government scrapped before it went into full production. I personally think that they were 'bought off' by the yanks who could also see it's potential, but that's another story.

 

So, take one TSR-2 [ATTACH]12996.vB[/ATTACH] and shorten it [ATTACH]12997.vB[/ATTACH]

 

Now play with the fuselage and hey presto, the VT-101 [ATTACH]12993.vB[/ATTACH] Still a bit basic and rather 'toy like', but I think it might have possibilities. At least it isn't another Cub or Jabbie clone, there's enough of them already.

 

Hope you found this interesting. If so, please add your comment and/or your story in the same vein.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Deskpilot]

As I can't find my original thread re the DeMansfield Bolt, I'll continue on this one. On HBA, we had much discussion about the problems with a propeller revolving around the tail boom. The greatest of these is, apparently, torsional resonance. Not being one to be beaten (tongue in cheek) I re-addressed this problem and have now isolated the prop from the boom altogether. Whilst my 'hub' design is currently somewhat bulky, you'll get the idea I'm pursuing. The hub is held inside a set of angular ball bearing races, which in turn are fixed to the main-frame. I'm thinking that if the hub is made of Carbon fibre with some alloy inserts, it will be relatively light. Got a lot in reading to do on that subject.

 

 

In order to complete the design, I needed a fairly accurate model of a VW engine but there isn't one available. Looking up Google SketchUp Warehouse, I found a couple of models suitable for car models and decided to use the best of both, correct the mistakes, remove twin downdraft carbies, correct the firing order, add a new inlet system, flywheel, starter motor and revamp the exhaust pipes(which still needs a cross coupling balance pipe). This is probably over-kill but it's been fun..................if you forget the frustration of the program crashing with such a large model. I initially modelled for a standard tractor set-up as below. This model will be available on SketchUp later on.

 

 

Any questions/comments always welcome.

 

 

 

 

 

[fly_tornado]

looks good

 

 

[turboplanner]

This thread will be buried like the one you refer to because when we want to look up something on aircraft design we won't remember to think of a horse and stable.

 

Maybe we should set up a series of threads under Aircraft Design, such as wing and aerofoil design, construction methods, materials, design configurations, engines, hardware and sub assemblies etc.

 

Forums were invented for people with a twenty second attention span, but the potential for serious discussion like yours is huge, with the ability to draw on world wide knowledge.

 

My take on your various wings is that they would be better suited for jet engined designs with faster speeds. They look good but I think you'd need faster take off speeds etc.

 

I was doing some theory work with Decca before he died and bought a book "Aerodynamics for Naval Aviators." ISBN 1-56027-140-X

 

It's heavy going, and doesn't give you design calculations, but it is very thorough and is used as part of Naval Pilot Training and covers a host of issues from sub sonic to transition to supersonic and why the wings are shaped the way they are, how each wind has to be flown etc.

 

A vectored thrust ringtail, if you were going to pivot the prop brings the complications closer to helicopter level, and you have to address prop aerodynamics during the arcing, so more weight, more expense, more maintenance.

 

The FanTrainer concept looks good - prop safety, much better vision down the nose, no prop strike etc.

 

We see a lot of these novel designs in RC Aircraft and it's interesting to watch them on the field, where often their shortcomings become very obvious - pitch problems with flying wings for example.

 

For your prop turning around the boom, some of the spokeless/hubless custom motor bike designs would work for a belt drive prop. You do have to think about vibration though fopr another aspect - if the prop sheds a skin/gets out of balance the major vibrations are still going to be passed back to the boom area, so you could lose the tail rather than just crack front engine mounts.

 

As an Industrial Designer, I'm continually frustrated in my work because I have to start with existing components, whereas in may training, I would start with a blank sheet of paper and look at what it would take to carry two people through the air at an acceptable cruise speed with the constraints being:

 

Post Peak Oil factors is now cycling conventional fuel costs in an ever steepening curve, approaching prohibitive cruise cost

 

Harmful, and Co2 Emissions are no longer acceptable, or must be minimised

 

Traditional Airfields are being sold off at an ever increasing rate

 

My thinking is a wing with a lot of lift, but very little drag, renewable energy.solar power boost, STOL.

 

 

[Litespeed]

Hi Deskpilot,

 

Always good to play designer even if they stay on paper.

 

Keep up the effort and have fun.

 

This type of discussion belongs in a dedicated design area, as Turbo suggested.

 

I have followed your ideas on HBA, interesting but not without challenges.

 

But if it was easy, everyone would do it.

 

Cheers

 

Litespeed

 

 

[Yenn]

Does anyone remember the twin, which had the wing around each engine shaped to follow the prop tip below the wing centreline. I believe one did fly and performed well, using the high speed propwash to give much increased lift. the problem was manufacturing the wing.

 

 

[facthunter]

All my concept designs have blown wings. The delta to me is for high speed flight and introduces hand.ling and low speed problems. I've followed all your stuff Doug . Keep it up. Everyone has to follow their own instincts. Well presented. nev

 

 

[merc]

custer channelwing

 

 

[Deskpilot]

Yes, Custer Channel wing, although it only went beneath the wing, not all around it. I "imitated' it some-what with my VT-ICE

 

 

Vectored Thrust-Inverted Channel Experimental Still thinking about the VT part but the channel needs to be on the bottom and a close fitting prop in it to make it work. This version of VT required,IMO, contra rotating props and the whole appendage moved to vector the 'straight line ' prop thrust. Not doable in reality. Now thinking on the more conventional single fixed prop with the duct moving around it. Strangely, had a new idea last night.....couldn't sleep, especially after the idea popped into my head.

 

REQUEST to Ian. Can we have a dedicated forums for home/own designs please. It will be interesting to see what other ideas are out there even if they're only scanned off a table napkin, where so many designs have started.

 

 

 

[sain]

REQUEST to Ian. Can we have a dedicated forums for home/own designs please. It will be interesting to see what other ideas are out there even if they're only scanned off a table napkin, where so many designs have started.

There is a design forum already. only the one post in it at present.

 

 

[Deskpilot]

Really? I'll go and look.