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Old Apr 19, 2011, 10:56 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
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Cardboard! Cereal box cardboard no less! Great stuff. Cereal box cardboard is the worst, but with some cutouts you could do well.

I am fascinated by the number of turns you can get - five hundred? Mine broke at 230!

For a wing you could try paper in the form suggested by Bruce Matthews. All you need is a roll of paper for a spar, to create the aerodynamic shape and thickness and another bamboo or wood stiffening spar as well. With this set up I have built a 40 cm (16") wing that weighs about 8 g. Or you could use bristol board and build a nice wing.

Will post some pix of the wing. I have tested a paper wing on a stick plane and it is quite tough, but heavy. Painting wrinkled it, but the plane flies all right. The wing is a 1:24 scale wing of a Cessna 180 except for thickness. Weight is 12g span is: 41 cm (16") aprox. It is painted with watercolor and sealed with white glue.
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Old Apr 19, 2011, 11:29 AM
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I tested some post office bands - lubricated with liquid soap. 3 bands got 350 turns... 1 about 150. The model uses proper FF rubber.
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Old Apr 21, 2011, 08:50 AM
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Another little mock up - again for an RC design...

This one is 8" span, 4.5g plus 1.5g nose weight. I didnt stint on the tape so it could be lighter. These little pistachio sized card jobs glide really well so I 'm tempted to put a small rubber motor in one.

Replacing the nose weight with a card or yoghurt pot propeller would probably work...
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Old Apr 21, 2011, 08:32 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
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Beautiful work, you certainly put me to shame. I hope many model builders around the world are inspired by this and are building one.

Card - how could it be 4.5 g are you sure about this? A paper wing weighs at least 4 g for me.

Make it more scale and paint it you have a winner
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Old Apr 22, 2011, 01:06 AM
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The 'Wack, BC, Canada
Joined Oct 2002
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Kn', that wing section I suggested in the sketch some time ago was intended to be done in card stock similar to that used for greeting cards and business cards. Not printer paper.

Although many years ago I did do a paper glider with a 22 inch wingspan using a similar paper airfoil and rolled paper tube for the fuselage. It actually glided quite well. But of course it would not resist an actual throw or even towing it up on a thread towline. It hung in my "shop", which was a closet under the stairs in my parent's house, for a couple of years and then I crumpled it up and tossed it when in a fit of cleaning up.
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Old Apr 22, 2011, 02:50 AM
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Quote:
Originally Posted by BMatthews View Post
... But of course it would not resist an actual throw or even towing it up on a thread towline..
Yes I'm finding that too - the wings are not stiff enough for a proper HLG lob. The little ones are made from stiffish card - the kind they have by the ton in schools (In fact it DID come from my school , sometime in the eighties!)

The wing is just a single thickness of card with no spar, but it's still tough enough for a few seconds glide from head height...

Hmm, "make it more scale" - It is scale: 1:4 scale of a RC trainer!
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Old Apr 30, 2011, 04:15 AM
Just shut up and build!
Sri Lanka
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Quote:
the wings are not stiff enough for a proper HLG lob
This is another subtle point that dawned on me - having constructed hand launched gliders until recently, I did not realize that a rubber powered model could be build much more lightly since is not going to be launched at 50 miles an hour or so, as needed by the HLG.

My Cessna is still progressing, flies OK but fast, I am putting the finishing touches on it now
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Old May 01, 2011, 07:03 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
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Photos of the Cessna

A flew good flights yesterday, despite the damage to the model. Attached are some pictures.

The model flies straight and level, with the emphasis on level, a 40 g monster is not going to break any time to height records. The rubber motor only spans half the fuselage so there is room for improving the 5 second or so flight times. Unlike previous models, it does have some reserve power.

To increase lift, I cut the flaps section and bent the card downwards about 30 degrees. There was a definite improvement in lift and flying performance.

Need to repair the model and test it out in a large field. No luxury of tall grass, and the model has already sustained an crash on its nose from 10ft ( 3 metres ) up, when a gust of wind pitched it up in a zoom climb, and it stalled. I am somewhat pleased with its durability, though, especially the wing and wing/fuselage attachment points. The fit and finish leaves something to be desired so I would appreciate comments on how to make it look better and neater.
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Old May 04, 2011, 01:11 AM
Grumpy old git.. Who me?
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Quote:
Originally Posted by knlever View Post
....The fit and finish leaves something to be desired so I would appreciate comments on how to make it look better and neater.
Practice, practice then practice some more....
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Old May 04, 2011, 07:29 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
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Hey thanks - it is fun, though, almost addictive. By the way , responses to posts are quite infrequent now - you guys all out flying - it is summer now ?? Well happy flying.
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Old May 31, 2011, 08:30 PM
Just shut up and build!
Sri Lanka
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I decided to build to 1:32 scale instead of the 1:24 scale. The smaller scale is more convenient, and the plans will fit on A4 pages. Wing loading will be higher, but using paper for the wings and other weight saving techniques it should fly well enough.

1:24 Scale Length: 33 cm Span 46 cm

1:32 Scale Length: 25 cm Span 34 cm

This means a 34% decrease in wing area. I will be building the wing bigger than scale, in this case.

The photos show the construction details of the fuselage. Using Bristol board instead of paper results in a smoother fuselage without any buckling of the material used. The center tunnel houses the single rubber band.

Right now weight with prop and rubber as installed is just over 23g. Cut outs and weight saving will come later.
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Old Jun 01, 2011, 01:11 PM
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The 'Wack, BC, Canada
Joined Oct 2002
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I hate to say it but at 23gms already for only about half the model for a 25cm span you may as well stop right now. That's far too heavy to fly well at all. An acceptable weight for just the fuselage and prop for this size would be about half that weight even for casual front yard sport flying.

You're going to need to find ways to use less material. For example I see that you're still using a motor tube and wrapping a fuselage around that tube. That's a lot of extra material to achieve what is basically a doubling up of the construction. Perhaps work on forming the outer skin into a U shape with a glued in top cap so it can be stiff enough to accept the rubber loading on it's own.

Even just making the tabs on the formers smaller would be a good step in the right direction.
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Old Nov 01, 2011, 08:05 PM
Just shut up and build!
Sri Lanka
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I have been continuing to build some test models. Got rid of the motor tube and tested a fuselage that could withstand the torque of the rubber motor upto about 100 turns or so.

Following previous advice, I have started experimenting with a non scale stick plane with originally a 40 cm span and weighing oh maybe 20 grams or so due to styrofoam wings. Replaced the styrofoam wings with bamboo and paper and the model flies surprisingly well, although impact resistance and water resistance is very low. (I'll say!) Also deformation is also a big problem.

All this will be solved with a new design taking inspiration from this designer in this post: already a test wing has been built and is quite strong but weighs 7g per side for a 30 cm span wing. Will post pictures of it all. What a journey.
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Old Nov 01, 2011, 09:13 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
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Stick Plane and test wings

Pix

How much does it weigh? I have realized that an accurate weighing scale is critical to this project, so I am building one at present. I have the weights for calibration.

Weighing scale post

Flew the stick plane with the pictured wing, covered with light covering paper. Due to the undercamber and the improved structure and the uniformity of the wing, it actually flies quite well, although heavy -maybe 35-40g, and does not change direction too much, very stable. This opens up all sorts of possibilities for cereal box cardboard.

I am not going for long flights, 15 seconds will be good enough if given the space. Cheap materials and easy building - there as to be a downside - but this is a great educational tool.
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Last edited by knlever; Nov 10, 2011 at 04:33 AM.
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Old Nov 27, 2011, 02:53 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
Stick 180 wings and tail

Pictures of stick plane with 180 wings and tail

Construction

Continuing the experimentation I have rebuilt the foam stick plane using cardboard wings and tail. The material used is "Bristol Board" or thin card.

The wing is made out of the cardboard with a single spar over which the cardboard is folded. The wing is solid cardboard.

The tail and rear stabilizer are single side thin cardboard except for the folded leading edge. The fuselage is the original wooden stick that came with the original plane model and is very stiff and strong. The propeller is a Guiilows like unit about 6 inches in diameter (15cm). Power is provided by a loop of 3mm wide rubber that can take upto 10 turns without breaking.

As you have guessed, the wings and tail are patterned after a 1/32 scale Cessna 180.

Specifications

Span: 40 cm (10 ")

Weight: 30 g (estimated)


Flying:

How does it fly? Quite well, given the fact that it is still unstable in pitch. After trimming out the initial tendency to bank left and turn it performed a few straight , stable flights on 140 turns. It does fly.

Durability
Durability is the key factor here: the pictures you see have been taken after about 10 flights, all of them ending in a sort of crash or another. Under these conditions the model has stood up quite well, thanks to the stick fuselage, rugged prop and also the material used.

Appearance
The material used makes for a relatively smooth finish that can be painted and finished nicely for a scale model. Basically the Cessna 180 wings and tail are done now, and the wing can be made somewhat lighter than this one.
Scale models now seem within reach, at least a scale model that will putter around the 'front yard' without breaking any endurance records. For a child who assembles and builds such a model, there is a great deal that can be learned from this model and can pave the way for model building.

Next Steps
A full fuselage model is under construction, and since weights are satisfactory for my purposes, it looks like it will fly as well. This model, lets call it the Stick 180, will be balanced properly and flown again, possible with added camber and more power.
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Last edited by knlever; Nov 27, 2011 at 03:13 AM. Reason: New info
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