An Experimental Vulcan: 72" span.

[Luther Oswalt]

I like this construction very much! Beautiful work!

Leo

[Devcon1]

That looks a fun project David, I bet it looks terrific in the air..

Out of interest what experiments have you planned for it and what sort of data will you be recording.

[Simon Chaddock]

Very interesting.

Is it the fore runner of something more complex?

[Former Member]

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[eflightray]

Posted by David Mellor on 01/04/2018 19:49:18:

Thanks chaps.

I'm interested in materials and structure, and how they influence flying weight and therefore performance.

Depron is an interesting material in that it is very cheap and very uniform. But it isn't a direct substitute for balsa in structural terms. I'm interested in exploring different ways of using depron to form viable structures.

The Vulcan is an especially interesting test case because the intrinsic cubic wing loading of the unladen full sized aircraft is extraordinarily low. This presents particular challenges for modellers who desire scale-like flight characteristics.

Just about everything I now build and fly is scratch built using Depron, with some balsa where thought necessary.

Link to my web page -- **LINK**

Some of the pages show some construction methods.

Ray.

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[Colin Leighfield]

David, thank you. I really enjoyed reading that. Deltas are ideal subjects for projects like this. Chris Golds did a profile Vulcan, the plan is probably available, although it was probably balsa? Several years ago I saw one hanging up in Inwoods, Huntingdon, for sale second hand. It had four EDFs. I was tempted and often wished that I’d bought it. I think profile models like this have a lot going for them and your innovative construction approach takes it further.

[Simon Chaddock]

David

Yes Depron is much weaker than balsa but it is also much lighter so its strength to weight performance is not that dissimilar.

If you can design a structure in such a way that all the stresses are below Depron's limit then it will need little or no reinforcing with weight savings as a consequence.

To my way of thinking the Vulcan in particular with its low wing loading and relatively thick wing section is a prime candidate for such a build approach.

[Nigel R]

Very neat model David and a nice account of the build too.

A couple of questions if I may

At this size, would you think the flat plate holds the model back at all?

What sort of weight would you project an all wood build to come in at, at this exact size (as I forget the numbers from the recent cubic loading thread)?

And would a wood central section + plug on depron wings have mileage as a build method? The U/C and so forth would have solid points to mount on (as you've observed in another thread).

The tissue over depron - heavyweight tissue I guess? And attached with what, PVA? One of the polyC varnishes?

[eflightray]

At 110oz (6lb -14oz) flying, the profile version is only 2Lbs lighter than my Depron 82" span full fuselage with built up wings version, also using twin pusher motors and retracts, (8Lbs - 12.5oz).

Ray.

Edited By eflightray on 03/04/2018 11:18:52

[Alan Jarvis]

My SHM 72" balsa and ply Vulcan comes in at 12.5 lbs

 

 

Edited By Alan Jarvis on 03/04/2018 12:08:41

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[John Stainforth]

David,

Thanks for sharing your clever, simple and cheap design of a Vulcan. The basic parameters (wing loading, power to weight ratio etc) are impressive and no doubt the model confirms some of the things that were discussed recently in the context of scaling and wing loading.