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Old Dec 28, 2012, 12:33 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
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Gliding towards free flight

After my latest attempt at rubber powered free flight, an attempt that we can best describe as having 'mixed results'. Previous attempts ie the "Cardboard Cessna 180" flew but were not durable enough.

Reviewing past posts and the kind comments in this forum, I decided to go back to basics and build simple gliders with 12" -14" span ( about 40 cm) for a start, to work out the aerodynamics and crash resistance.

Initial tests have been encouraging, hope to post some pix of an all card glider here.

What I have learned so far:
  • A model that glides slowly has a better chance of being powered by the weak, short burst of power that the rubber motors I am using provides
  • A model that requires a powerful throw to fly is a less likely candidate.
  • For a 30 cm long model, a 20 cm solid card wing is just marginal, and is is surprising to me what a difference card is compared to foam or balsa
  • Since it is diffult to keep the weight down, better try building a larger model, as the relative density of the model goes down, and the larger area will support greater weight. Some rubber powered models weigh 100 g or more with a 28" : 70 cm plus wing.
  • The crash resistance and durabilty I require absolutely needs stronger materials - no long tall grass here.
Admittedly I should have taken the advice and built a non - scale model first!

Ah well
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Last edited by knlever; Dec 28, 2012 at 12:42 AM.
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Old Jan 24, 2013, 03:45 PM
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John Moore's Avatar
Southern Spain
Joined Nov 2003
236 Posts
I do not understand this message.
I thought you were busy on a micro ducted fan?
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Old Jan 26, 2013, 12:24 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
I am once again involved on several projects at the same time. It seems like it is taking ages, but I have made some progress. I admit the previous post is not very helpful.

It is simply that I have realized that I should build a non - powered version of the model to test flight loads, impact strength, stability and durability.

So I will build:
  • An 1/32 scale jet glider ( Saab Tunnan) ( for the EDF project)
  • A 1/32 scale Cessna 180 glider ( for the Cessna 180 project )


I have now on my desk a card model that can survive an impact with a brick wall several times ( except for the propeller) .

Getting the airframe right (strong enough and light enough) is a common requirement for Micro EDF, rubber power, gliders and so on.

I have read of an example of a balsa model that got destroyed falling off a shelf. I am not really going to be working with that level of fragility. I don't like working with foam either, though I tried it in my early experiments.
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