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May 17, 2017, 12:21 AM
Registered User
Help!

Improving Gliding


So I'm a beginner who has scratch built a foamie and flown it a couple of times.
I have thought of two ways of improving glide time but not sure whether it would work.

1.Parachute on wings
A stretched sheet on top of the wing which can be released to act as parachutes.
Would the plane stall and go down straight?

2.Extra Wingspan
Create a cavity inside the wing and add a secondary wing which can be pushed out using a channel at will?


Has anyone tried anything similar to this?
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May 17, 2017, 02:00 AM
Registered User
Grup's Avatar
Quote:
Originally Posted by leo271
So I'm a beginner who has scratch built a foamie and flown it a couple of times.
I have thought of two ways of improving glide time but not sure whether it would work.

1.Parachute on wings
A stretched sheet on top of the wing which can be released to act as parachutes.
Would the plane stall and go down straight?

2.Extra Wingspan
Create a cavity inside the wing and add a secondary wing which can be pushed out using a channel at will?


Has anyone tried anything similar to this?
Maybe 2, not 1. You talked about "improving glide time", yet in 1) you asked "would the plane stall and go down straight?" Well, probably much more the case than it would make the plane glide more. So this option is "NO this won't work".

2: I believe people have actually done something like this, except it does not involve a cavity inside the wing, with a secondary wing. It is building a swing wing similar to F14, F111, etc., which has less lift and drag when tucked in, and more lift and drag when extended. This actually is proven technology; and I have even seen it work on a model plane. Which was build by a beginner who had never flown. The maiden was done by a highly skilled person, and his comments were "it flies well".

Regards
May 17, 2017, 05:04 AM
An itch?. Scratch build.
eflightray's Avatar
Assuming you mean with power off.

To improve the gliding time, reduce the drag, better design and use a folding prop, and keep the weight down, (wing loading).

Learn about and search for thermals, (rising air, or slope soaring), otherwise the model will be descending.

Learn more about the different wing sections and how they can affect flight. If you want a good 'glider', i.e. not powered, look at what the glider fliers are using.

Probably 9 times out of 10, gimmicks rare work and that's the reason why they are not popular.

Ray.
May 20, 2017, 10:20 AM
B for Bruce
BMatthews's Avatar
The first option is a route to shorter air times, not longer. Model and full size sailplanes are designed like they are to obtain the greatest flight times from the least possible use of energy. In this case altitude. The cleanest and lowest drag figures will provide the longer flight times.

The second option could work but it requires special fabrication techniques to ensure that the larger "sleeve" can be strong enough to support the flight loads when the inner piece is not inside and able to force the sleeve to hold its shape.

All in all the route to longer flights or flying with less power is to make your models look more like gliders or powered gliders. And also to keep the weight on the lighter side so the wing loading is reduced. That slows down both the required flying speed as well as the descent rate.

If you simply want to fly slowly then a good way to add wing area is to design and build biplanes. Keep the interplane gap at or larger than the larger wing chord for best performance. The optimum interplane gap is more around 1.5x the larger wing chord or more. But making the gap between the wings much larger than 1.5x the larger chord leads to other odd handling issues.


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