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Old Oct 21, 2009, 09:32 AM
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Question
Riser 100 motorization?

Hi,

i am going to build a SIG Riser 100. As i live in an area which is very flat i want to install an electric drive.

It seems to be a real problem to find a motor/prop combo for the bird ;-) As i have to order something from hobbyking it would be nice if i can use a motor from them. But which one? And which prop?

I want to use my 3s1p 1800-2220 mAh lipos for the riser. The accus are 20C. I think something in the range of 160-200 Watts should lift the Riser in an "adequate" climbing? That means something about 16-20 Amps current. Because of the low speed of such a model a low-kv brushless is needed?

I found the hexTronik DT750 Brushless Outrunner 750kv. Does it fit in the Riser? I think i have to extend the fuselage front because the motor is lightweight?

Another motor i found is TR 35-48-C 800kv. Much more weight and much more power? Should be capable of climbing the Riser 100 vertically. But is the Riser stable enough for this much power?

Anyone out there who has experience with motorizing the Riser 100? I just want to fly slowly. I want to sail. Motor is just a replacement for a high start.

Thanx in advance,

Udo
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Old Oct 21, 2009, 04:19 PM
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I'm currently building an electric Riser 100. Here's a link to my build thread with lots of pictures:

http://www.rcgroups.com/forums/showthread.php?t=1119189

The HXT motor looks like it will be under-powered for the job. Also, the 35-48 is likely way overkill, weighs more than you need it to, and you might have trouble fitting it in the fuse without widening it.

Here is the motor I went with:

http://hobbycity.com/hobbycity/store...6_910Kv_/_310w

I have static tested it with a HobbyCity 13x7 folding prop and headless spinner. It pulled 22 amps at full throttle. I'm using a 60A Super Simple ESC and separate BEC, but if I had to do it again, I'd probably go with a 40A. If you're building it in stock configuration and only need to power two servos (I'm powering six), you might want to consider the Mystery 40A ESC with built in BEC. I have one in my Parkzone Trojan and so far it's been working great.

I don't know if I have a good picture of it in my build thread, but the Turnigy SK motor is a pretty tight squeeze in the fuse.

I hope to fly it for the first time this Friday and I'll let you know how it goes. Before I started putting on the covering, this motor/prop combo had close to a 1:1 thrust to weight ratio.
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Old Oct 21, 2009, 04:32 PM
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The KDA 22-20 does very well.
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Old Oct 21, 2009, 04:37 PM
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Hi,

thanks. I saw your thread and that the maiden flight is to come ;-) What about the CG? I think with such a lightweight motor i have to extend the front part of the fuselage? That may mean that there is not enough for the motor... Hobbycity gives no dimensions for the TGY AerodriveXp SK Series 35-36 910Kv. Can you please tell me the diameter?

Thankx,
Udo
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Old Oct 21, 2009, 04:47 PM
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CG is still just a guess for me, too. I know that the stock version, without a motor, needs quite a bit of nose weight to balance. The motor and battery might make up for that. Also, move the servos back one bay so they are under the wings. I hope to finish covering by tomorrow night, so I'll have a better answer then.

I think the Turnigy naming system is diameter-length. That would make my motor 35mm wide and 36mm long.
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Old Oct 21, 2009, 04:54 PM
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Quote:
Originally Posted by Lockley
The KDA 22-20 does very well.
Can you tell me more? Which angle is the Riser 100 climbing with this motor? What prop do you use? How long does it take to climb to the end of visibility *g*

Ciao, Udo
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Old Oct 21, 2009, 05:10 PM
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I use an 11-8 prop with a 2200 Mha bat for several climb outs. Angle of climb is about 35 degrees and speed is nice with only slight down on the elevator. Motor is set to about 5 degree down and centered.

You will find that the Riser 100 will go to the limits of your sight in a mild thermal. I usually climb to about 800 to 1000 FT. and search for the wing to tip or see the plane rise. Do have your spoilers working well. Dave
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Old Oct 22, 2009, 03:47 AM
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ubit,

Lockley is pretty much dead on for the motor and ESC. This will allow you to use your 2200 mah batteries that you already have. As for the motors, the AXI 2820/10 is the choice to use in the Riser 100 builds. Its a trade to the KDA 20-20's. Or if you can find something similar. Bob in Seattle did a build awhile back with a smaller motor at it flies very well, with a good 45 degree climb.

There is an article in the Feb 2001 S&E Modeler mag on converting the Sig 100" Riser glider to electric.

Here are a few build threads to look at for more information:

http://www.rcgroups.com/forums/showt...electric+riser

http://www.rcgroups.com/forums/showt...electric+riser

http://www.rcgroups.com/forums/showt...electric+riser

http://www.rcgroups.com/forums/showt...electric+riser

http://www.rcgroups.com/forums/showt...electric+riser

These are just a few of the many that you can find here. Along with a great bunch of guys to answer your questions. Just keep thinking , the one question you don't know, is the one that you don't ask. Advice is given freely. Most of all, HAVE FUN!!!

tink
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Old Oct 22, 2009, 04:35 PM
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http://www.stefanv.com/rcstuff/riser100.html

Dave.
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Old Oct 22, 2009, 06:23 PM
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Thanx, Dave. I saw your site ;-)

I decided to use the following motor:

http://hobbycity.com/hobbycity/store...idProduct=3888

This should give me a couple of options for choosing a prop. First i will try an Aeronaut 11x4 folding prop. With this i should have about 1 kg thrust at 16 A current. Nearly 80% efficiency according to drive calculator. And i have the option of using other props up to a configuration where weight = thrust - what is in my eyes way too much for a plane like the riser 100... But with the 11x4 i should be able to climb in a couple of seconds to a height where i nearly can see the bird.
I will report of success in a couple of month (not too much time for building the kit...).

Ciao, Udo
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Old Oct 23, 2009, 05:01 AM
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ubit,

Good choice on the motor. I would go to a 11X6 instead of the 11X4. Like you said , you can adjust up or down as you see the need. Keep us posted.

Lyle
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Old Oct 23, 2009, 06:14 AM
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I think Riser 100 flies very slowly. So a 11x4 should be adequate cause it produces a slower thruststream. I will see how it works.

Ciao, Udo
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Old Oct 25, 2009, 11:11 PM
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I updated my build thread with my findings. 55 ounces of thrust pulling an all up weight of 61 ounces. Your plane will definitely come out lighter than mine. I also had to mount all my electronics way far forward, but again, all the weight I added was behind the desired balance point. Ideally the battery would go in the second bay (just in front of the wings) which you could probably do with a stock build (except of course, for the electronics mods).

I'd also suggest slightly more on the prop than what you've picked out. But at least with that motor you'll have room to experiment. I'm certain you'll go vertical with the right prop. I've seen some electric Riser 100 builds on here come out less than 50 ounces.

I know you want to keep it slow flying and that is fine. But, if I may offer my opinion, a larger prop doesn't really cost you much of a weight penalty, but it will get you to altitude much quicker. Might as well take advantage of what you have. If all you want to use is an 11x4, a motor half the weight of the 35-48 would get you that. I'm not saying you're wrong, just offering another viewpoint. Plenty of people say the Riser doesn't need ailerons but I built them anyway.

Here's my post with more info: http://www.rcgroups.com/forums/showp...8&postcount=23
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Old Nov 25, 2009, 06:24 AM
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Hi,

in the meantime i continued building my riser 100. I got the motor i wish to use:

Turnigy TR 35-48-B 900kv

Yesterday i received the prop. I ordered 11x4 and 11x6 aeronaut folding blades with 52 mm (2") centerpiece. I build a simple test stand for checking how high thrust is.

With a TowerPro H40A Brushless Speed Controller and Zippy 3s1p 2200 mAh 20C i got approximatly 1100 g (nearly 39 oz) thrust with the 11x4. The 11x6 give about 1400 g (nearly 50 oz) static thrust at 7770 rpm.

Currently i cannot measure amps. But neither motor nor speed controller or zippy get warm after 30 sec.

I think the motor/prop combination should pull the riser 100 strong enough for a lot of fun. And i still have the option of using more cells and larger props for climbing vertical if i like.

Ciao, Udo
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Old Nov 29, 2009, 08:57 AM
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Hi,

now i have the complete data from my thrust stand:

11x4 aeronaut camcarbon folding prop with 52 mm centerpiece:
8600 rpm, 17 Amps, static thrust about 1100 g (39 oz)

11x6 aeronaut camcarbon folding prop with 52 mm centerpiece:
7770 rpm, 22 Amps, static thrust about 1400 g (nearly 50 oz)

These values match quite well with the values calculated by drivecalculator. With motor and esc i have the option of using 4s for vertical climb if i intend to.

Ciao, Udo
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