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slowing down for a landing

Old 02-27-2010, 01:23 PM
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1fasthitman
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Default slowing down for a landing

I just converted my .40 size pattern plane to electric. I'm trying to get a handle on landing it. It comes in pretty hot approaching the runway. I'm accustomed to my glow engine that idles on it's own and the prop naturally slows down the plane. What's the best technique for electrics? Should I just add a little throttle with my finger on the stick, or maybe add a little trim on the throttle to let it spin on it's own?
Old 02-27-2010, 02:38 PM
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Jetdesign
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Default RE: slowing down for a landing

Double check your CG. Electric setups are generally heavier than glow, and a resulting forward CG will make it land hotter.
Old 02-27-2010, 06:16 PM
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Default RE: slowing down for a landing

You can always set up an airbrake function - the opposite of flaps. Up aileron - about 30% to 35% to start with, and slight down elevator - about 8% to 10%. Deploy the airbrake right before you turn base leg, and drag the plane in, works great.

Adrian
Old 02-27-2010, 06:39 PM
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Default RE: slowing down for a landing

You can set an idle manually, use an esc brake function, add flaps or spoilers, or slow down before turning final and then use "blips" of power to bring it in.

You set an idle by starting with your throttle trim at the lowest point. Before takeoff you advance the trim forward until you have an "idle" that suits your needs. If your esc has a brake function I would start with the lowest setting and move up to see if you notice any change. Personally I found spoilers to be the most effective option, and there I believe you will need to consult your transmitter manual to see what's needed and then experiment with the values suggested by Adrian.

Good-luck and I hope you'll let us know what you end up doing; if anything


Joe
Old 02-27-2010, 11:58 PM
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1fasthitman
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Default RE: slowing down for a landing

I will try all of the above and see what works best. Thanks to all.
Old 02-28-2010, 10:44 AM
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Walt Thyng
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Default RE: slowing down for a landing

Since you are new to electric the first thing I would check is the brake function on the esc, It should be off. The prop will then spin freely providing drag. The next step is to use a tach to find and "idle" speed that matches the wet-power planes you are used to. You would probably best do this with the motor trim. If you have an advanced radio you may be able to build this in, just watch that you don't conflict with the safe start function in most modern ESCs which require a low throttle signal before they will arm.
Walt
Old 02-28-2010, 10:55 AM
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Default RE: slowing down for a landing

Walt, should the prop not come to a complete stop with the throttle all the way back?
Old 02-28-2010, 11:27 AM
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tIANci
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Default RE: slowing down for a landing

If its not CG then try to flare her more with some throttle, its like a semi harrier, slows the plane down. That is what I do.
Old 02-28-2010, 01:42 PM
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Default RE: slowing down for a landing

Practice! Practice! Practice! I have had the same issue with most of my planes early on their lives and I found that each has its own quirks when it come to landing. It is just a matter of time before you get used to it.

With a CG that is not too far forward, I will start to gently pull on the elevator slow the airplane down and then use the throttle to control the sink rate. In essence, I will just blip the throttle as I am coming in. This used to be easier with the gas powered planes because you could hear the engine, but it works with electrics as well. If I am carrying way too much speed, then I will splip the airplane slightly to use its side as an airbrake. You can do this by cross controlling the rudder and ailerons but you have to be careful; if you get too slow, the plane will stall and spin in. I do not know if one way is better than the other, but I try to fly the low wing into the wind. Use the rudder to keep runway heading.

Good luck,

Teo
Old 02-28-2010, 02:48 PM
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Walt Thyng
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Default RE: slowing down for a landing

No, the prop on an electric motor will windmill unless you have the brake on. That's why they have the braking function on some ESCs. If you turned off a wet-power motor and it had no compression it, too, would windmill. Electric motors have no compression (some high performance motors have a "cogging" effect, but not enough to stop a prop in flight). Theonly reason an e-power prop stops on the ground is that there is no air flow. Remeber airflow is powerful. In full scale planes we are taught how to restart a stalled engine in flight using airflow alone scary, but awesome.

electric motors require something called EDF backflow or something like that, which is what the braking function enables. I'm not an EE so I may have the language wrong, but the idea is correct.
Walt

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