Building materials, covering

[yogi94]

When we built a helicopter, we first used really light shopping bag covering as suggested on this forum. However, it didn't fly. When the covering was changed to paper (think wide-ruled, school paper) the time was about 30 seconds. The paper was much, much, heavier.. Any explanations?

[jander14indoor]

I suspect more changed than just the covering to make it fly. Many have been successful with the light grocery bags.
Assuming otherwise equal, lighter ALWAYS beats heavier in flight. So something else must not have been equal.
Can you post pictures of both copters? Describe how they are the same/different. Overall weight of both? Rubber used? Winds? Etc...

Jeff Anderson
Livonia, MI

[yogi94]

It was the exact same helicopter, we just removed the plastic covering and put on the paper. The rubber was also the same.. 3/32, double looped, total weight about 4g +/- .25

The only thing that could have changed was the added weight from the paper.

[jander14indoor]

If the weights were that close, and nothing else changed when you recovered I'm REALLY surprised. The light plastic works, use it myself and seen MANY other teams do well with it.

Hmmm, how tight was the plastic? Only thing I can GUESS is it was loose and billowy? If so, may not have been as effective an airfoil as the paper. Only a guess.

Alternatively, did you wind the plastic covered helicopter the wrong way and the paper one the right?

So far you are presenting an interesting puzzle.

Jeff Anderson
Livonia, MI

[yogi94]

I think it might have something to do with the plastic? It was rectangular and one of the sides was uncovered and the plastic wasn't the tightest. We wound both the same way.

[Kovu]

Whenever we put mylar on it seems to not be as tight as it should be, any suggestions on how to make it tighter?

[illusionist]

Whenever we put mylar on it seems to not be as tight as it should be, any suggestions on how to make it tighter?

Here is one method (scroll down until you see it).
I use grocery bags instead of mylar (much easier, not much of a weight problem), and the way I do it is that I start at the outside edge of the rotor, and slowly lay down a section, ensuring that I pull it tight, make that section stick, and then do the next section of the rotor blade.

[chia]

Whenever we put mylar on it seems to not be as tight as it should be, any suggestions on how to make it tighter?

If you do use mylar, wrinkle up the piece you're going to cover with before you glue - it makes it a lot more manageable and easier to keep tight.

[jander14indoor]

Don't overdo tight, too much will distort that very lightweight frame you spent so much time getting right. A little looseness is OK.

Jeff Anderson
Livonia, MI

[Kovu]

Okay, ill try some of those ideas we have a decent method just trying to make it better.