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No motor on an ASK 21 Glider


Junior Member
Okay I bought an ASK 21 80'' wingspan EPO model a while back, it did have a motor on the front with a folding prop, but I used the motor on something else now.

Is there any possibility that the glider will work with out a motor and be good for slope soaring ??

I don't really know much about gliders and slope soaring, but I do know the model will be light, it is 4ch aswell.




Rotor Riot!
A glider without a motor will be more difficult to fly as you need to rely on thermals and updrafts to maintain altitude.

The only thing you should do is check that the Center of Gravity is balanced since you took out a great deal of weight from the plane.



Old age member
All gliders are better without motor - that is why they are called gliders.
As for slope soaring - you don't need any motor - just wind.
Get a nose cone or make it from foam and fill it with the weight to compensate for the old motor and battery.
You will of course need a receiver battery - 4 or 5 cell NiMh are good.
http://stevewebb.co.uk/index.php?pid=RIPO4EN2000AASF&area=BATTERY Eneloop are fine batteries - low self discharge.

You want a slope glider slightly nose heavy compared to a thermal.
Also - with higher wind - you want to ballast the center of the plane with some lead - 100 to 500 grams are normal depending on wind speeds.
Do you have good slopes in Somerset?
You can try to get help from the RCM&E forum where you find local slope soarers who will help you find the places and get you in the air safely.
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Brian fred carr

Site Moderator
Once you have set the plane up Sam find one o them lovely hills in somerset, and making
sure the wind is a against and being pushed up the hill. Launch that baby into the wind
and see how long you can keep her up its great fun and you never run out of fuel....until the wind dies
Slope Soaring

It's also great exercise walking down the hill to retrieve your plane, then walking back up.

That will go away as you get better.

Then you'll get fat.

But seriously, slope soaring is really cool. I have a UMX ASK-21 and a hill within walking distance from my house. I also have the UMX-Radian, and I use it as a scout plane.

Here is what I do:*

I look for a calm day with cumulus cloud formations. Those clouds occur when convection cells bring hot moist air from the ground up to higher, cooler elevations. The water vapor cools off and forms the clouds, gets cold and heavy and sinks back to the ground to start the cycle all over again.

I take the UMX Radian and the UMX ASK-21 up to the top of a hill and face the direction the air is moving over the top of a ridge. I fly the UMX Radian until I've figured out where the lift is. I'm old and not as slim as I used to be, so I don't walk up and down the hills so well. So the UMX Radian Scout, lets me figure out exactly how the air is moving up the slope and across the slope when the wind direction changes. I figure out how good the lift is at the top of the slope and how fast it's moving as it is free to go sideways instead of up.

Once I'm in a situation where I know where the lift is, then I turn off the UMX Radian motor and slope soar with it

Then I land it when the battery is so low the motor makes it's warning noise. The UMX Radian electronics are set to warn you of low voltage (Nice).

Then I launch the ASK-21 and enjoy the beauty of that airframe gliding through the air. As much as possible, I try to keep it over my head and in front of me. When the lift goes away, I land it before it sinks below the lip of the hill.

When the lift is really good, I fly it out in front of me and dive it down the hill and then let the lift bring it back over my head.

I think it's a very, very cool way to enjoy flying RC planes.

Hope this helps

BTW, understanding the Terrain Features of the hill you are flying on is very important. See below for a blog I'm writing (it gets a bit obsessive about Terrain, but then Terrain is both the reason we can slope soar, and one of the reasons we crash so much, so yeah, my obsession is an out growth of my experience learning to fly).


* 20 years ago, they didn't have good, light electric motors, and I wasn't good enough to soar with the eagles in the thermals (launching from flat ground) so all I did was slope soaring. I found a place with some flyers that were really good and that motivated me to get better.