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A Cardboard RC plane.

Just how hard can it be?

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Simon Chaddock10/12/2016 01:17:40
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On the RC Groups web site a thread showed a 'scratch built' type plane neatly built from cereal packet cardboard.

It looked to have passable aerodynamics but it did of course use carbon rod reinforcing in the wing.

Having just finished a packet of "Crispy minis" I noted that the packet is made from a very thin but rather dense cardboard.

Could this cardboard be used as a structural skin as I do with thin Depron?

A simple bending test with two identically shaped pieces showed the cardboard has a similar bending strength to 2 mm Depron suggesting it would resist a similar load in compression. It would of course be many times stronger than Depron in tension.

Weighing the test pieces on my jewellers scale showed that the cardboard was exactly 3.4 times heavier than 2 mm Depron. That might sound a lot but then Depron is very light. wink 2

This would suggest that if a cardboard skin can be supported to significantly improve its 'buckling' strength it should be possible to make a plane with 'adequate' strength from this type of cardboard without an undue weight penalty.

Still thinking about the best way to achieve this

.

Former Member10/12/2016 01:40:35
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[This posting has been removed]

Rosco10/12/2016 01:42:19
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I tried building a model with a foamboard frame and a cardboard skin once Simon.

I found that the cardboard skin wasn't quite holding itself to shape (if that makes sense). For example, there was quite a bit more sag between the wing ribs that I anticipated. I also tried paper mache'ing it but that was what finished it in the end. I might have got away with it had I not done that.
I never finished the project but I'm not saying that it can't be done.

Unfortunately I can't post links from my phone but cut and paste should get you to this one......
https://www.google.com.au/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3D4Pf_Qiy5J6s&ved=0ahUKEwjR29uMu-jQAhUBPrwKHapsBqYQtwIIGTAA&usg=AFQjCNH4j9pjG7cg0Z3YEfd9RFIQ3m1j1Q&sig2=oljwqVJS95x6Dr6SRoMOQA

Here is my attempt. Sorry but you'll need to read through the thread to see the progress. It starts from the last post on the page (by oldschoolhg (me)).....

https://www.rcgroups.com/forums/showthread.php?2165336-Aussie-Foamboarders/page16

Rosco

Edited By Rosco on 10/12/2016 02:10:03

Former Member10/12/2016 07:38:23

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Frank Skilbeck10/12/2016 08:05:50
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Posted by Percy Verance on 10/12/2016 07:38:23:

Cardboard models are not a new concept. The Stanley Apprentice 60 inch trainer was made mostly from corrugated cardboard back in the late 70's. As I recall (I built one) it did have some wood parts in areas needing strength. It wasn't a roaring success, but a there were a few around at the time.

We did notice at the time though, that once they started to become even slightly oil soaked it was game over.......

Edited By Percy Verance on 10/12/2016 07:52:12

I had one wit an OS40FS up front, flew really well and I don't recall any fuel soaking issues.

Former Member10/12/2016 08:07:42

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Peter Miller10/12/2016 08:15:00
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There have been one or two others. About 10 years ago there was one which I forget completely (I know that sounds daft!) but a club member was going to review it.

Ithad a sortg of glossy surface. Theprpblem was that no glue could be made to work on it.

Onematerial that seems to ave been forgotten is Correx. There were a range of kits made out of it.

There were also some designs. I did one called Blue Movie.

Now they were a bit crude but totally indestructable.The material is used for notices, especially house for sale notices

Former Member10/12/2016 08:17:57

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Rosco10/12/2016 08:42:12
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.....that stuff is called 'corflute' here in OZ.

Rosco
Peter Miller10/12/2016 09:03:04
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That.s right. Actually I think Aircore used a thinner form of Correx than the notices. I did have some samples of the thinner stuff.

I made Blue Movie out of thicker material. a single sheet was enought to build a 48" span high wing model. I believe that it is still in someone's attic!!

I know that one was build in Canada. I am still in touch with the builder.

Martin Harris10/12/2016 10:11:58
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Were you thinking of the Regal Eagle from Paper Aviation? These were lovely models, similar in size and style to the Mahers Pacer/Thunderbird so cardboard isn't just reseved for smaller models. If I remember correctly, the one that I was lucky enough to have a go with was powered by a Laser 150.

As I understand it, the "plan" was printed on the cardboard skin and foamboard ribs and formers were glued onto it. I think the last of them were produced around the turn of the century - I'm sure there must be some former builders/owners on the forum who could give more details.

Mowerman10/12/2016 10:17:29
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Cardsharp was made from corrugated card an was a free plan in the mag about14 /15 years ago. I built one but the >15 diesel I used was a pig to start and I managed to rip it out of the model when trying, that, sadly, was the end of it.

I believe the plan is still available.

ChrisB10/12/2016 11:23:46
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Good old paper aviation. If I remember correctly they produced an ezzypeezy and the regal eagle. I never managed to get my hands on one but I always liked the eagle.

Phil May10/12/2016 11:46:34
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Peter...Not forgotten...

A 52" span Mig correx sloper I built and have flown with great success....One of a dozen or so all correx models I've built over the last 2 years...

fb_img_1449299989537.jpg

Simon Chaddock10/12/2016 12:35:12
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This is the Cardsharp

As a form of construction it is not quite what I had in mind.

Whilst I am sure the cardboard contributes to the overall strength it still uses quite a bit of wood and ply to carry the primary loads.

The cardboard I intend to use is very thin 0.018" (0.46 mm) so it will need considerable support to enable it to achieve anything like its maximum capability in compression - exactly the same problem with thin aluminium sheet in full size! wink 2

I have used thin 1 mm balsa as the outer skin of a box spar but otherwise made entirely of thin Depron sheet.

Eppler195

1 piece test build

It was only built as a 'test' piece but in theory thin cardboard could be used in the same sort of way.

A small test spar built as a card/Depron/card "I" beam.

100_2101

100_2102

So perhaps what is needed is a complex Depron structure but covered in cardboard.

kc10/12/2016 12:58:00
6412 forum posts
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There was an article about cardboard construction in RCME Feb 1988 by JR Newberry. He used card from Thames Board Mills in Cumbria. thickness 500 microns, weight 300grams /sq metre. high quality outer surface to take print.

He used a spiked wheel to simulate rivets.

( Simon - PM me if you need a copy of the article, however an actual copy of the mag is on sale for 1.40. )

All very similar to the later Regal Eagle kits.

Someone ( Roy Garner? ) did an RCMW review of a Stanley model and used actual Weetabix cardboard with the Weetabix logo allover but I think he used large sheets rather than packets. This makes me think the Stanley model were not corrugated but smooth cardboard like Newberry used. I think the review said you made the Stanley model from the cardboard box it came in!

Edited By kc on 10/12/2016 13:04:39

Former Member10/12/2016 14:43:59

[This posting has been removed]

Simon Chaddock10/12/2016 17:15:56
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kc

It would appear the cardboard I am using is the same thickness but slightly heavier at 375 g/sqm but then it is gloss printed on one side which actually makes it very nearly water proof.

Stuphedd10/12/2016 17:30:40
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I had a Stanley Craftsman , in fact 2 of them , Powered by Merco 61s all cardboard !

Chris B should remember my red and yellow one , They actually flew very well , I gave it away , and it was not fuel soaked !!

The Craftsman was the low winger ..

cheers

kc10/12/2016 17:33:06
6412 forum posts
173 photos

Stanley Models also did a Craftsman low wing at 60 inch span. Kit cost 14 pounds in 1983.

Peter Russell's S& L column had a drawing of the Apprentice 60 wing which proves Percy was right - it was corrugated cardboard. This is the drawing

cardwing.jpg

Various other items in RCME also show corrugated card such as Mike Smart's Pappendeckel plan in Sept 1980 and an article by Chris Pinchbeck in Sept 1977. However later articles and kits seem to use non corrugated. I am sure the Regal Eagle used plain card for the wing with 3/8 sq balsa spars. J R Newberry used gloss surfaced card for his Airspeed oxford & 3/8 scale Turbulent.

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