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Old Aug 15, 2010, 09:20 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
642 Posts
Build Log
Cessna 180 - Rubber powered, cardboard and paper construction

I am starting this build thread not knowing if it will end up in a flying model or not. Previous tests have shown the high probability of the model actually flying.

I want the model to look like this:

http://www.rcgroups.com/forums/showt...=993275&page=3

First step: download the plans if there are any or draw up the plans. This is a scale build so finish will be very important.
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Old Aug 15, 2010, 02:45 PM
SlingWinger
San Bernardino, California, United States
Joined Oct 2004
1,629 Posts
You may be familiar with Paul Bradley's site. He has made it so that you can print a color scheme directly onto balsa, to build a replica of some of the old Carl Goldberg and Top Flite "Jigtime" all sheet balsa rubber models.

If your printer won't do balsa you can print on paper or even tissue. I'm considering printing on light paper then laminating that to sheet foam. Just gotta get my local 'puter guru over to fix it so I can print.

Anyway, one of the Goldberg models is a Cessna 180. When properly built and trimmed it flies very well.

These kits came with a steel washer to be used as nose weight. We learned that we could sand all the balsa that was aft of the CG very thin, and could omit the weight of the washer plus what we sanded away. These planes could challenge a stick 'n' tissue plane of similar size.

It is my opinion that while a paper and cardboard version may fly, a model using foam sheet will be much lighter and fly better.

It is probably true that "Balsa flies Better". But foam is a reasonable substitute when balsa isn't handy, for most structural applications.

Remember that it's strength-to-weight ratio and stiffness-to-weight ratio that determines a material's suitability for flying models. Even if the only foam you can get is pie plates from the grocery store, it's bound to fly better than cardboard. Small sections of foam sheet can be butt-joined together to make larger pieces. Laminating with tissue adds a color scheme and additional strength for very little weight.

God is Light, and in free flight lightness is God.

Good luck with your project.
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Old Aug 15, 2010, 07:46 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
642 Posts
Thanks but I would rather not use foam although freely available as waste. Cardboard is biodegradable and less messy. I also use the cereal box type cardboard although the thin card type is available, bio degradable and very cheap. Why? In order to re-use waste materials. Once I finish experimenting I may use other materials to build my final model.

The plans you mentioned are what I used to build by first 1:26 Cessna 180, however I would like to build a model that is a bit more scale like the one in the link above.

If anyone can send me free plans of the 180 that would help, otherwise I will base it on the Paul Bradley model and make my own plans.

Thanks
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Old Aug 21, 2010, 04:03 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
642 Posts
Printing out the Paul Bradley plan set. The PDF has to be printed 130% to obtain the correct size span of 20 inches ( 50 cm) . This was the mistake I made the last time and printed out a model too small.
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Old Sep 06, 2010, 07:17 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
642 Posts
Update: Still making the plans the correct size, and modifying them for the construction methods I will use. A nice thick wing should slow the plane down nicely

Creating the plans more difficult than I thought.
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Old Sep 06, 2010, 08:28 PM
B for Bruce
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The 'Wack, BC, Canada
Joined Oct 2002
11,154 Posts
Thick wings on small rubber models don't work well at all. The size our models are and the speeds they fly at rewards using thin airfoils. If you want to slow the model down use more camber in the airfoil. But don't get carried away. Again for small models more than about 4% camber (the camber line where this is measured is the curved like that runs midway between the upper and lower surfaces of the airfoil) and all you get is too much drag.
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Old Sep 07, 2010, 06:05 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
642 Posts
Bruce, so which airfoil should I use? You sent me a few on this thread:

http://www.rcgroups.com/forums/showt...1299364&page=2

I thought of using the full airfoil and flattening down by scaling the height down by 50%. Is this a bad idea? Will change the airfoil characteristics completely? Maybe camber it a little - maybe I am looking at a thinner, cambered airfoil on Google

:http://en.wikipedia.org/wiki/Airfoil

There is a picture of airfoils or to be more correct aerofoils towards the lower part of the page. This one looks OK -"laminar flow airfoil for a RC park flyer"- ( but it is Wikipedia after all - "oh and the airfoil is from Wikipedia" "Wikipedia?" )
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Old Sep 15, 2010, 10:47 AM
Airplane Dope
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USA, WI, Rio
Joined Nov 2009
329 Posts
CardBoard and paper? Might work, but I've tried to make flying Cardboard models but they didn't fly good. Dollar Tree Foam Board (and maybe EPP, Depron and FFF, but never tried them) is not as messy, but still of course there is the "Green" issue that you mentioned. If you want a Good Flying plane, go for Foam or Balsa. If you want a biodegradable plane go the cardboard/paper or balsa way. (balsa would be more biodegradable.) Good Luck, and hope you succeed!

EDIT: I might try with Cardboard/Paper sometime.
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Old Sep 16, 2010, 10:00 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
642 Posts
Balsa is not available in the country where I live. In any case I think cardboard is easier to use.

I have built and flown the following models

Limited Success:

- Cessna 180 ( Yes it is from the late 1970s!)
http://www.rcgroups.com/forums/attac...mentid=3129568

( Very fast, needs a lot of space, powerful motor)

- Me 109
http://www.guillow.com/GuillowDetail...20&FamilyId=1#

( Two flights or so before it crashed. )

Successful:

- Foam spitfire ( Picture not available)

- 1:26 Paper and card Cessna 180 ( see my thread http://www.rcgroups.com/forums/showthread.php?t=1280452

I prefer the cardboard and paper model the best - I may be able to improve greatly on the above model.
Easier to get paper and cardboard and bamboo.
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Old Sep 21, 2010, 07:58 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
642 Posts
Update - test wing

My first test wing was completed yesterday. I covered the top with tissue and used water to wet the surface - it was all wrinkled when I finished. However this morning it looked reasonably tight.

One problem is that the cardboard ribs will not support chordwise compression loads - which I did not factor into the equation. I am not covering with 80gsm just too heavy and a tight fit needs to be maintained.

The covering has to be tight to avoid those other two problems - flutter and ballooning, which show up on a video I saw of a sheet balsa glider.

This glider uses bamboo for reinforcement:

http://www.rcgroups.com/forums/showt...1122412&page=3
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Old Jan 29, 2011, 01:25 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
642 Posts
Flew a semi- scale model today, so the thing looks feasible. 29 cm / 20 grams, rubber powered.
Sustained flight.

I did an FAQ on why I am using cardboard and paper: I reproduce it here from my earlier post:

An FAQ on why I am using cardboard. I explain it all.

Why Cardboard - FAQ
I am in the process of experimenting with model planes made out of paper, cardboard and bamboo. There have been may questions, no doubt, as to why I am using cardboard instead of Balsa, the Holy Grail of flying model construction materials.

This FAQ will explain my reasons for using the materials I use,

Q: Why cardboard, paper and bamboo ?
A: Partly due to experience. I have built paper models in the past, (1:100 scale gliders of jets ) and I have been able to achieve quite a realistic form and finish. Durability was a huge problem, which I hope to address this time.

Q: Have you ever built a balsa model?
A: Yes, I Guillows ME 109. The full model. I covered it with polythene. It actually flew, quite nicely once I go t it trimmed, but only two flights. After that it crashed and was never re-built. A recently flew a foam -winged 40 cm span stick model which flew very nicely in the limited space I have.

Q: Any other models - foam for example?
A: Yes I have assembled form models of a Monogram Cessna 180 and a Spitfire . The Spitfire flew well, I had a lot of space to fly that one, the best flying model I ever had

Q: So why cardboard etc?
A: Several reasons. First is availability. The second is that is tis easy to work with and does not leave such a mess. The third reason is that it is easy to finish. It is biodegradable.

Q: Do you know of anyone else who has done the same thing?
A: Yes. I remember a magazine article in the 80s of a model 'built entirely out of card'. There are several successful R/C models built out of corrugated cardboard, the most famous probably here. These models are all fairly large.
As far as building rubber powered or micro RC airplanes - I am not the first to try it, however I could not find anything on the web. There is a site about control line cardboard models, though.

Q: Have you had any success with the concept?
A: Yes. I finally was able to build a 40 cm span model of a Cessna 180 capable of sustained flight. In retrospect a larger propeller would have helped. The model was built smaller than planned due to the wrong size of plan printout, with higher wing loading than planned, weighing a total of 35-40 g. I have since built a 20g non - scale model, and hope to test it soon.

Q: What are your future plans?
A: To build many scale rubber powered flying models. I want to publish the plans on the web. Maybe produce a cardboard cut out kit later on. Initially the models will be used for short flights. I want to research into extending flight times and carrying radio equipment. A 1 minute flying would be quite enough. Of course one could use the power to gain height and glide back down. There is at least one rubber powered R/C plane on You Tube ( search for it ), however the owner uses a stretch winding technique, and again it is a larger aircraft. The ultimate would be a spring powered model, AIr Hogs has already sold an air powered model, air being a kind of a spring.

Jan 2011

http://www.rcgroups.com/forums/showt...1370164&page=7
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Old Jan 29, 2011, 05:33 PM
Airplane Dope
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USA, WI, Rio
Joined Nov 2009
329 Posts
Cool! Post some pics.
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Old Jan 29, 2011, 11:49 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
642 Posts
Lets start with some information . The search term "cessna 180 walk around" netted the following:

http://www.grubby-fingers-aircraft-i...alkaround.html
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Old Jan 30, 2011, 01:58 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
11,119 Posts
knlever,
We all have our own benchmark for what a 'successful' freeflight model is. For some the model must be able to regularly achieve a two minute 'max' in competition, others are happy with much less providing the model flies in a stable way and doesn't crash.
For the rocket powered jet models I used to fly regularly many called it a successful flight if the model is still in the air at the end of the motor run (about 20-25 seconds). I believe in some indoor contests a 'flight' is acknowledged if the model is airborne for 15 seconds.

I'm wondering when you say your models are successful because they achieved 'sustained flight'... what does that mean?

Steve
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Old Jan 30, 2011, 02:31 AM
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Yak 52's Avatar
UK
Joined Jan 2009
1,248 Posts
Knlever,

As Steve says, flight times are a more objective way to measure 'success'.

Can you give some construction details?
Do you have access to corrugated cardboard (stronger in compression)


The Cessna 180 has lots of compound curves to play with anyway...



Jon
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