Depron!

[Frank Day]

Hi,

Always questions i'm affraid.

 

I've never built using foam but am planning a conversion on an old foamie! weren't around last time i did this. Converting a Robbe Concorde from twin pusher to EDF. Main edf mounts will be ply/balsa but planning to construct the rest of the nacelles from foam.

 

I need a small amount of foam sheet material in 3 & 5-6mm and am not sure what im looking at. Have seen some listings for multi sheet packs of the stuff but probably need little more than a couple of A4 size pieces.

 

I think I read that Depron doesnt exist anymore.

 

Advice welcome as always.

[Murat Kece 1]

6mm exists at: https://www.balsacabin.co.uk/product/depron-sheet/

[Murat Kece 1]

https://www.ebay.co.uk/itm/192884513671?hash=item2ce8d01b87:g:wXIAAOSwUm5cLhsq also has grey in different sizes

[Eric Robson]

Hi Frank,

I thought Depron was extinct but it is around in another form, I bought some sheets of 5 mm from B&Q but they only sell them in multi packs and to date I have not found any at 3mm. Foam board again in 5mm thickness can be obtained from Hobbycraft stores, the supply single sheets @£4 per sheet, discount if you buy 4 sheets.

These sheets are 33"x 23" approx. they are faced on both sides with paper and are quite firm, the paper can be removed but it is not an easy task and I have heard of some people reducing the thickness with a hot wire. 

I have built a few models with foam board and it is not bad to work with, blunts Stanley knife blades quickly and I use UHU Por glue for joining, 

[Frank Day]

Thanks, 

I saw the paper fronted stuff listed for picture framing use and the grey stuff on ebay but it looked like strange narrow strips of whatever so I skipped by it.

 

Frank

[Zflyer]

I have used Depron and also makerboard, the latter comes in various thicknesses . I have used the Hobbycraft board and its true to say that the paper covering is a real swine to remove, so now i don't bother. Hot glue, although does add weight, is fine to use along with pva and uhu.

[Dad_flyer]

Paper comes off the Hobbycraft board best with hot water. Heat on its own does not work, and cold water is not easy, but with warm or hot water it parts company pretty well. It is not very easy to take of the paper from only part of a sheet. 

As it is an art board, the paper seems to be coated and is very heavy. Taking paper off both sides halves the weight, but it is then much less stiff of course.

[Frank Day]

Thanks Guys I picked up a grey mixed pack from ebay

[Erfolg]

Hmmm, seems that Depron is becoming extinct, pity. Is it to save the planet I wonder?

[EarlyBird]

On 07/04/2022 at 15:16, Frank Day said:

I think I read that Depron doesnt exist anymore.

Depron Foam - Insulation

 

 

 

[EarlyBird]

and from

 

 

in smaller quantities.

 

Steve

[eflightray]

There was Depron, and there is something that is also being called Depron.

If you were an original Depron builder, you just know the difference as soon as you pick a sheet up.

But, if you 'need' to build, you can just about use anything.

I've mentioned it before, look for the 'grain effect' in Depron, similar to how the grain in balsa sheet will roll easier one way, but most likely break/snap the other way.

I still have a small amount of the 6mm original for a 'special occasion', but not enough for another big build, (6mm for structural and 3mm for external skin), the remaining 3mm I have is the 'grey', (grey ?, as often the reference to 'aliens', not of this world)

As I have implied, any material can be used.

 

Ray.

[leccyflyer]

Like Ray said, a lot of the depron around today isn't the same as the original Depron from the nineties, which had a very clear grain and also had a more resilient skin to it. The modern grey stuff seems significantly softer and bruises very easily. The old stuff would take a fingernail impression, wheras the grey 6mm is softer and even a gentle sanding needs to be done with great care to prevent surface plucking.

[EarlyBird]

Thanks for the information. The good news is that a form of Depron is available and can be used, with care, to build models. ?

 

Steve

[leccyflyer]

Indeed. I sourced a pack of the grey 6mm last year and though I found it rather painful to finish, compared to the Depron that I was used to in earlier times, it can still make a nice model. Some of my clubmates are making fantastic models with depron, which fly beautifully - as a material it really lends itself to experimentation.

 

One of the most impressive EDF models that I've seen is John Davidson's magnificent EE Lightning, which I swear climbs faster than the real thing! John's twin EDF Phantom is another spirited performer. Another clubmate Bob has crafted a lovely fleet of the SEMFF profile depron fighters, which he's passed several on to me and I'm hugely enjoying flying them. My own Mustang III doesn't perform quite as well as his Zero, Bf109e and Bearcat, but I'm really happy with it. Likewise the several mid-wing pusher propjet Su27, Su37 and Mig 29s which are regularly  tearing up the sky at the field. There are several of the STOL Tundra-like depron models at my other club - Tosh who posts here has a lovely example and my pal Derek is just completing a gigantic F104 Starfighter, having successfully flown a smaller version and a similarly huge Buccaneer.

[David Davis]

I am a traditional balsa and ply aeromodeller.

 

Given the incease in the price of balsa, could depron be used for sheeting fuselage sides and wing leading edge? Could you use it to make wing ribs?  If not, what other materials could be used?

 

[Don Fry]

Wing ribs, direct replacement, as ribs are not heavily loaded.

fusalage formers, ditto, might need a few stiffening balsa strips.

But not the wing centre section, and real load bearing formers.

you can replace LE sheet, fus sides, but you start to get ding, hanger rash, like a foamy.

Just remember, you are replacing with foam, what the designer used balsa for. If the balsa is over-engineering, replace or modify.

[Graham Davies 3]

Hi David,

Whilst not quite the same stuff as the depron discussed above, I am a massive evangelist for foamboard. Given that I remove the paper on both sides, I am effectively building with depron.

 

My latest build is a 55" Regianne RE2005. The difference between this build and a conventional build is likely to be around 2 pounds in weight. I'm not targeting ultra-light, but a different build material that just happens to be a lot lighter than conventional materials. This gives me some significant advantages: I can fly these size models on 3S packs, giving me more flights when I bring the 4S models too, and I can use retracts on our bumpy field s they are less stressed.

 

To answer your question, I have been using foamboard for ribs on conventional builds for some time. Regarding sheeting, yes, but it has less strength and is less resiliant than wood, so needs a lot of care, and thought to ensure the overall strength remains. You can see from the pictures that I have used a conventional balsa spar with balsa webs and a ply dihedral brace on this build, but I expect this wing to be more than strong enough.

 

The big differences though are cost and speed of build. For me, this takes out a lot of the fear of disaster as less is invested in the model, and therefore makes these models a huge amount of fun.

 

Graham

 

[Graham Davies 3]

Oh, one more thing. As Dom states, it is soft and as such I laminate 1/8" balsa for leading edges or the model soon looks tatty.

[Nigel R]

22 hours ago, David Davis said:

Given the incease in the price of balsa, could depron be used for sheeting fuselage sides and wing leading edge? Could you use it to make wing ribs?

 

As Don's list for me - Formers, ribs, anything without much load on it.

 

On a "smart" model I'd keep the finished surfaces in wood. But with care and appropriate covering it can replace sheeting.

 

Fuselage sheet sides? I'd want to make structure with wood underneath, I think. Not sure it would survive handling on a big model. A bit too squashy.

 

I've made flat sheet tailplanes and controls from foamboard. Works pretty well. Do stick some balsa around the edge for hinges and LE and tips. Careful with the covering iron, don't heat the foam too much - it balloons, and stays ballooned. Fake ribs (cap strips?) make it look more kosher.

 

YMMV.

[Erfolg]

My main interest with respect to this thread is where Depron sheet can be purchased. I had not realised it is going the way of Blue Foam (Dupont Floormate), that is pretty much extinct.

 

What may intrest some in passing is that I have recently finished a model (not yet flown) in the so called "Grey Stuff". As suggested I have found it difficult to use.

 

 

The picture includes the material that it is made from.

The model is a facsimile. of the same design (with one motor, where the original had two, lower powered motors)

 

The next pictures shows the gery stuff in the model

 

 

 

as can be seen I have included a lot of reinforcement as it is nowhere near as stiff and dent repellent as the Depron sheet that can be seen in the first picture.

 

You may wonder why the emphasis on strength. In the past I have flown Depron models in unforgiving weather. Depron required very little extra stiffeners to provide an allweather model. The Grey Stuff, is not as good for this. As indicated by others, It does not sand well, nor does it cut as well.

 

I have been considering building a Gotha 244 using the paper covered Depron, leaving the paper on, as I suspect the additional strength from the paper will come at a minimal weight increase, with the benefit of a viable all UK weather model. What are others views?

[Simon Chaddock]

To be exact Depron is still made by the Depron company but it is more flexible. less rigid and lighter than the original stuff. Furthermore it apparently is not distributed by them in the UK. Someone has to import it which makes it rather expensive. The joys of BREXIT.

There are 3 mm and 6 mm white sheet foams from other sources which similarly are more flexible and lighter that the original Depron. This does make it easier to 'form' but it also is not as rigid.

It all comes down to adjusting the construction techniques and applications to suit the properties of the foam to hand, just as it does for any aeromodelling material. ?.   

[EarlyBird]

7 hours ago, Simon Chaddock said:

The joys of BREXIT.

Nothing to do with brexit. VAT has now to be included after years of VAT free prices.

 

Steve

[Eric Robson]

This is my Me 110 made from foam board and maker foam and grey depron, it is 57" span and has had over 60 flights it fly's in strong winds and has withstood a mid air collision with a Viper jet which it destroyed , only damage was a dent in the trailing edge of the starboard wing. Basic construction was a foam board box to which formers were added then clad with grey depron, the tail plane is maker foam doubled over and the leading edge covered in strips of A4 printer paper as are the wing leading edges. The wing is flat bottom with a 1/8" ply main spar and a second spar further back made of foam board. It weighs 3lb ready to fly with a 3s 3000 battery. There is no wing ribs in the construction just spars.

There is some pictures of the build under My foamboard Me110.  

Edited April 13, 2022 by Eric Robson
added some text.

[Graham Davies 3]

Similar to Eric's excellent Me110, this is my Ki-45.

 

Similar construction to Eric's methods, but with a 1/4" balsa main spar, and balsa leading edges to wing and tailplane. It's covered in brown paper/ PVA and painted with emulsion paint thinned and sprayed. My cowls are 3D printed and the whole lot is 3 1/2lbs ready to fly with a 2200 3S lipo. 60" span and I get 5 minutes from this little pack. It's now had over a dozen flights including in some stiff breezes. It flies great...