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Some ideas for scratch built Depron fuselages.

Depron techniques.

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eflightray27/03/2014 20:42:27
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607 forum posts
128 photos

I thought I would show these pictures of my current method of scratch building fuselages from Depron.

The general method seems to be full formers, perhaps built on a central crutch.

I build a box first and add outer part formers for the skins.

The box gives strength plus it gives you a very handy place to put all the RC rear, battery(s) etc.

Might be worth a consideration for future models, the choice as always is the builders.

My Dauntless and Spitfire fuselages --

sbd1.jpg

sbd2.jpg

sbd5.jpg

sbd7.jpg

spitfire4.jpg

spitfire6.jpg

eflghtray.

Stuphedd27/03/2014 21:25:01
685 forum posts
357 photos

love it !! super shot looking down the fuz .

is its 6mm depron!!!

how do you bend depron?? thin skin. ???

cheers

eflightray28/03/2014 13:02:47
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607 forum posts
128 photos

Yes the main box and formers are 6mm, then I generally skin with 3mm.

Depron has a sort of 'grain', a little like balsa has, and will bend easier one way than the other. I pre-shape the skins by either rubbing them over the edge of my work top, or roll them over a tube, (old bottom section on a fishing pole).

The recent Depron I have bought, seems to have a harder skin on one side and doesn't bend as easy as some of my previous stock. The trick to stop it cracking is to put tape on the 'outside surface' of the sheet, (packing tape etc), prior to bending, then slowly build up the bend.

My previous Depron sheets were much more flexible, it could be the manufacturer has changed something, though sanding the hard skin does seem to improve bendability.

The two finished models--

Scratch built, (no plans), Douglas Dauntless, 67" span.

Scratch built, (based on TN's plan, free in mag), Spitfire, 72" span.

sbd25.jpg

spitfire25.jpg

eflightray.

stu knowles28/03/2014 13:48:54
586 forum posts
44 photos

Brilliant stuff Ray.. Yours were the first '3D' depron models that I ever came across and I thought (think) that they are amazing. Then I walked into the shop in Rotherham which had Roys 100" Vulcan on show and I was just blown away. I think that it's a whole new development of modelling. Can't wait to have a go (It will have to wait until the current list are built!)

Congratulations to everyone who posts Deppy builds on here. All inspirational stuff

stu k

Devcon128/03/2014 14:24:59
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1400 forum posts
489 photos

Hi,

Great building and techniques. What glues do you use for the various types of joints.

John

Electriflier28/03/2014 14:47:26
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474 forum posts
1210 photos

Nice work Ray!

Being that I'm always ready to learn may I ask how you accurately measure and cut the fuselage formers to accurately fit the tapered box section. Do you use a jig to ensure correct alignment?
Also, how do you reference the fuselage centre/motor thrust line as I can't see any lines on the box sides?

Keep up the good work
Regards
Roy

eflightray28/03/2014 14:56:55
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607 forum posts
128 photos
Posted by John Milne on 28/03/2014 14:24:59:

Hi,

Great building and techniques. What glues do you use for the various types of joints.

John

My favorite is UHU Por, but have tried most types, - wood glues, (fair but slow), epoxy, (can be quick, or messy), hot glue, (watch the temperature and amount, it melts Depron), Gorilla glue, (great stuff but can expand a lot and look messy), even used, 'Use No Nails', (wall board stuff, good for sticking wing skins on as slow drying). Never liked the foam safe cyno.

Depron building is very similar to balsa, just cheaper. I have even seen a thread in another forum of a Depron built turbine model.

My avatar is another of my 'Deprons' - Sunderland 90" span.

eflightray28/03/2014 15:07:57
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607 forum posts
128 photos

Alignment Roy ?, what's that

I'm a model builder, not an engineer

A roll of wallpaper backing paper, some straight edges, pencils, pens, and angles, and a tin of pins, the rest is 'by eye'.

For the Dauntless I did use Google SketchUp and a 3-view to work out how big and how long a box, (technology at it's best).

With a box construction you automatically get straight edges, (you hope), so it should be straight to build.

It's amazing what you can get away with under the skin, they all look pretty when finished and in photographs.

 

 

Edited By eflightray neath on 28/03/2014 15:08:57

Simon Chaddock05/04/2014 23:35:03
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5610 forum posts
2972 photos

eflightray

A very impressive build and as you say "building" in Depron uses very similar techniques to balsa but volume for volume it is much cheaper and lighter.

On the subject of lightness quite a bit of your final structure does not really carry its fair share of any load. Basically the internal square 'box' is there to facilitate construction but will provide little extra strength once the continuous outer skin is in place.

If you can build it a true monocoque over formers is just as strong and considerably lighter.

This view looking down the fuselage of my all 3mm Depron Scale V-1 'Buzz' Bomb shows the technique.

Cable runs

With no internal structure the skin provides all the strength - however it is not the quickest thing to put together. wink 2

 

 

Edited By Simon Chaddock on 05/04/2014 23:37:10

lightning 75915/09/2015 07:56:13
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148 forum posts
10 photos

Hi Ray

got any building tips & Pics for the wing building part ,what do you use for rhe spars ?? Ply ??

andy

Graham R15/09/2015 14:11:02
325 forum posts
24 photos

Very much like your work Ray.

Depron is soft and easily marks/dents. How do you prevent this and do you use a covering to smooth out the texture before painting.

Graham

Dave Hopkin15/09/2015 15:05:53
3672 forum posts
294 photos

Depron can be made more ding resistant using water based varnish, Poly-C or Ezecoat are sold specifically for this, though Ronseal Diamond Hard Floor varnish is the same stuff and half the price, lightweight glass fibre tissue can be bonded to the surface to add extra protection, dents in Depron can be steamed out, a cloth dunked in boiling water and then draped over the dent (or hold the model near the spout of a boiling kettle) will cause the air spaces that were compressed in the damage to swell and "heal" the dent - most vanish totally

Getting a totally smooth finish prior to paining, I use a mix of Lightweight Fliier (B&Q) mixed with Water Varnish to give a double cream consistency, spread on then sanded back

Peter Hill16/02/2017 23:25:41
19 forum posts

Hi Ray. Have you ever done a step by step build blog on this or any other forum? Would love to see more detail on your particular building method(s).

Regards Pete.

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