I noticed the wing is positioned differently on the two pictures. Do you trim the cg with moving the wing position? It's actually quite a nice way to trim a model, no additional weight needed. You might wanna increase the dihedral if it's an option.

Nice work knlever

The wing is mounted on a pylon which is why it looks different in each picture. I wanted the wing height to approximately match the wing height of the Cessna 172.

Moving the wing is a good way to change the CG, however in a scale model this is not an option. Thanks for the compliment I am working towards scale appearance and finish.

Building a few more models, and a few years on, especially with my paper and cardboard P-40 that flies for 5 seconds, I understand rubber powered flight much better now.

The P-40 flies nice and straight for 5 seconds, then falls from the sky. The critical factor is motor running time. Thinking back to the rubber powered models I have seen flying both on video and real life, I realize that essentially at the heart of these models is a low - rpm, long running rubber motor with a large prop. That seems to be the key. Winding up a Guillows type stick model with a larger prop got me 15 seconds of running time, which is a big increase.

So the plan is to build the motor first, run the prop and see if I get 20 seconds of running time. Then build a model with the wing loading that will fly, I think I can do this by using more paper than cardboard, paper is very strong, and I have tested a paper - spar wing that stands up well to wear and tear.

Waste of time posting!

Hope this is not a waste of time posting but here goes:

I must say I was very impressed by the kind helpful remarks of everyone who has contributed so far. I downloaded these pages and read them offline slowly - what a difference it makes - and so much information in these pages .

I am attempting again to build a cardboard / paper 180. This time with more knowledge and a few more experiences in building. My latest glider is 40 cm and weighs about 14g which is a huge improvement.

I will build each component and test for weight so the total comes to 20g or less.

Other changes:

• Build own prop
• Build as to avoid nose weight
• Build a glider first and sort out trimming/durability/crash resistance issues
• Neater building
• Use thinner material than bamboo - coconut leaf spines are good
• Use copper wire where needed to stiffen the wing for example
• Do a lot of testing indoors - model should be light enough and durable enough for that

Also hope to post videos this time

First step - refining and calibrating my weighing scale

Forget about the copper wire. It's far too heavy and simply not springy enough for the amount it weighs. If you need to stiffen something find other options.

A hint for if you need wire then get some unwound guitar strings and straighten them. You can straighten them by holding one end in a vise or other securing setup and the other end in an electric hand drill. Then while holding a LOT of tension run the drill for about 15 to 25 turns. This will straighten the wire nicely and from there you can use it for landing gears and other uses. This trick should work for wire up to around .030 thick. Beyond that I doubt if you can pull hard enough while running the hand drill.

Use copper wire where needed to stiffen the wing for example

Copper wire is made to be flexible. How will that stiffen a cardboard wing?
Bamboo can be sliced to 0.5mm or less quite easily and weighs nothing in comparison to copper wire and you can sand it to a smooth surface.

Will try both and see how much each weighs. Actually the load will be carried by a main spar of cardboard or paper. Cardboard or paper does not have good impact resistance, that is where the copper wire will come in, bending, absorbing the strength and either springing back or be bent back. Bamboo is good, too, same thing here, impact strength.

In larger scale, conditions for good flyability are much better, as wing loading control gets less critical....

Watch THIS video.....the model is built entirely of cardboard and paper.....
This is a design degree project by Anna Poijo......impressive, and fun....

knlever, Maybe you can succeed using the model in the video as a guide for construction. The thing I'm thinking of now to solve the rubber stress problem is with a tube. You could make experiments and go with the least possible weight for a tube inside the fuselage from prop shaft to rear motor mount, but no more, if you can calculate what size rubber motor would be needed and go with the least as possible. With a fuselage tube you wouldn't need to make the fuse form all that strong. It would only need to be shaped. The wing could be supported with rolled paper tubes, also, as main spars. And paper is paper, so if condenser paper is readily available you could cover with that. I wouldn't try to use water shrunken tissue after covering as that would most likely pull the frames way out of shape unless you pre shrink first and leave it at that.

Kev

Hi

Surprised to see people are still posting to this thread.

Very interesting video, thanks. I see they are using corrugated card for the construction, and there is an excellent site, as well as a recent model magazine article that I was lucky enough to purchase, that outlines how to build models out of corrugated cardboard.

I plan to yet again try to build a Cessna 180, I feel I have the right knowledge now, however as always, the problem is durability and crash resistance: I do not have the flying sites to fly these, any more. This means making short flights into trees or brick walls.

I will be looking into some sort of RTP model flying. I will probably build the Cessna as a proof of concept but that is it.

Actually I want to use a stick plane like I tested in this thread at the top of the page, and add a card fuselage and bigger, lighter wing. That should do the trick.

The Cessna 180 is a nice, stable model that will mean the difference between success and failure.

Don't worry about building for crash resistance, build it to fly.

Kev

Originally Posted by kevin matthews

Don't worry about building for crash resistance, build it to fly.

Well said..!

The more "crash resistant" you build, the more severe crashes you'll get..!
Thinking the opposite way is the way to go..