Project Feasibility - Wyvern

[Dave Cooper]

Hi all. Not sure if I'm on the right forum but here goes:- I'm ex-Fleet Air Arm (engineering) and would like to attempt an advanced Westland Wyvern project. Main design preferences to include a working turbo-prop unit (with contra-props), double wing-fold, full retracts, lowering deck hook and torpedo release.

Most likely prototype would be the S4 variant (Python turbine /Suez Campaign), but, others also considered if more appropriate. Questions arise over scale size - 1/4 or 1/5 to accommodate a suitable turbine unit. Also, the wing folding - what would be the best way to power it. Variable pitch props - a bridge too far ? I think the retracts, deck hook and torpedo drop should be fairly straight-forward to engineer with existing methods.

Any helpful tips re plans, proven technical solutions etc would be well received. Timescales: 3 to 5 years ?

[stewart clifford]

Hi Dave

Most of what your looking for is possible, I think a guy in the States has built one at that scale(1/5th i think). It's a big aeroplane, I think 1/4 would really do it justice. The engine isn't a problem, retracts, hook, torpedo all fine. Vairable pitch prop, unlikely, contra rotating not sure.
Arthur Bentley may be a good source for the drawings.

If your not aready in the LMA then I would recommend you join as this model will be over 20kg, you'll also get a lot of help and advice too.


Stewart

[Dave Cooper]

Thanks for the advice and encouragement Stewart. The thinking on the props was that as they would need a reduction gearbox anyway, I could add a (reversing) co-axial shaft drive plus some fly-weights to operate the pitch change. There is, of course, the problem of the dreaded inter-shaft bearing to cope with ! (we had some serious wear problems with these on the FAA Gannets). Any ideas on how best to contact Arthur Bentley ? Another forum perhaps. Once the project looks like a 'goer', I'll certainly be joining the Association...ps forgot to mention the Youngman flaps requirement for the in-board mainplane (the outer is a more simple split-flap arrangement).

[Barrie King]

Hi Dave, check this out for a previous build, not using a turboprop,
http://www.modelairplanenews.com/blog/2 ... nd-wyvern/
gives an idea of the size etc.
Barrie

[Dave Cooper]

Thanks Barrie - I found a video of this one on Youtube but it's nice to have some tech' as well from the magazine source. A very impressive model indeed. I see he's neatly 'side-stepped' the contra-prop drive issue by making on of them a free-wheeling unit. I suspect he's not bothered with variable pitch (VP) either ! I spent this morning on some planetary gear designs and a simple VP unit based on helicopter principles. The challenge will be in making it light enough whilst still being able to constrain the inertial loads.

[Barrie King]

Dave, it may be worth having a word with Mike Murphy at Wren Turbines, he does build one off turboprops based on the 44 Gold engine, he is currently doing a heavy duty one for Steve Bishop to use at the shows.
Barrie

[Chris Lane]

There was a superb scratchbuilt Bearcat bought by a member, if I recall correctly, and it appears in the WWII part of our gallery. That had a variable pitch constant speed airscrew. Perhaps some research on that one would provide some of the information you need? Good luck. Chris

[Dave Cooper]

Thanks Barrie and Chris. I will pursue these contacts when time permits. (I've just had a request for a painting of Jim Clark's Lotus 33 for a birthday present, so, will have to do some research on that asap !). Yes, the Bearcat is indeed a magnificent piece of model engineering. I think the designer/builder may have been Dutch. Coincidentally, I'm practicing with a Bearcat on my RC flight sim' at present - it's the nearest I can get to a Wyvern with the current version of the software...

[Phil Clark]

If you'd like to get in touch with Dave Wigley, the builder of the 1/5 Wyvern mentioned above, let me know.......I've been in contact with him over the last few years as I've supplied parts for his current project.

e-mail me at - phil@fighteraces.co.uk

Phil

[Dave Cooper]

Hi Phil - thanks. I may well need to talk to him at some point. I think I saw an ad' for his plan somewhere ? Been discussing powertrain ideas with Wren Turbines this week. Am currently working on design ideas for the contra-prop gearbox and variable pitch units. If I were to go for 1/4 scale would you be able to supply any suitable parts ? Will email a 'wish-list' to you when things are a bit more advanced...

[Phil Clark]

Hi dave

Drop me an e-mail to phil@fighteraces.co.uk and I'll pass on Dave Wigley's contact details.

Yes, there is a plan available via Model Airplane News in the US....as well as basic 3-views for the retracts

http://www.modelairplanenews.com/blog/2008/11/12/custom-made-retractable-landing-gear-for-the-westland-wyvern-s-4/

Regarding bits.....nothing specific to the Wyvern, but I'm sure we can help with various building & finishing materials (glass cloth, resin, paints etc...), wing tubes, retract air system accessories, control linkage items etc etc.

Cheers

Phil

[Dave Cooper]

All - thanks for the many contributions to this. My conclusion is that the project is feasible at 1/4 scale but will be very demanding of time, resources etc. and, I think a 3-5 year timescale may be necessary to sort out the detailed engineering issues. Progress so far includes an in-depth look at contra-gearboxes and variable pitch units. Today, I finished some first trials on a pair of (small-scale) o/d contra-props running co-axially in plain bearings. Next will be a mock-up of the planetary geartrain and the two prop control units (these will probably be in wood /plastic at this stage). There is some turbo-prop engine discussion on the "Jet" forum and I will add to this as appropriate. The hunt is now on for generating a set of 1/4 scale plans and drawings. Next move will be to join the LMA and get the project registered in the over 20Kg category !