Large electric gliders forum - RC Groups
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Feb 10, 2003, 06:41 PM
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Large electric gliders forum

I would like to initiate a discussion around large electric-powered gliders. Let's arbitrarily call "large" 3 meter wingspan and greater. I have been actively involved with aerotowing scale gliders in the 4 to 7 meter range for the past 7-8 years. Prior to that I was flying low-end hotliners such as Robbe Arcus, Robbe Calibra, Aeronaut Sunfly and Fruednthaler Surprise II.

The independence(can fly anytime/anywhere you want) of electric,
coupled with the performance I experienced with large scale gliders has me excited about mating these two areas of RC.
The advances/availablity of electrics have come so far in the past 8 years, I can't believe it! I can remember sending sending cash to the Czech republic to get fuselages/motors etc. Now just get out the plastic- the choices/performance are amazing!

I can't believe what is available in Germany, while we remain pretty far behind in America. To start things off let me describe my current project - I live in cold, snowy New York. Over 12 years ago I purchased a Pegasus fiberglass fuselage (Stan Watson design 167" span, ClarkY). I am building a set of 5 meter wings,
Hq 13/3 11" root tapering to 6" HQ 10/3 tip - 23-to-1 apsect ratio to use with this fuselage. The wings are built up with carbon fiber spar and balsa ribs/D-Tube. I am trying to get a light sailplane that will thermal and climb well on 16 cells.

Poweplants being considered are Aveox, Hacker, Mega, and Actro.
Hope to spin a 16 to 18" prop. Shooting for 12 lbs auw.

ARF glider wish list:

1)Simprop Solution XL(4m)
2)Blue Airlines Albatross(4.9M)

Please share your large electric experiences/ambitions in this forum!!!
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Feb 11, 2003, 12:12 PM
RCGroups Author
SoarNeck's Avatar
Funnily enough, I came to the same conclusion recently. I've always liked scale ships, but they have a couple of drawbacks...especially in the larger sizes. Namely, they don't winch very well off of a short, rough field, and most need a good launch since they aren't the type of model to be pinching at 10 ft with. Aerotowing is a great alternative, but our club doesn't have a good tug (yet).

Although our club is blessed with quite a few usable slopes seeing as how the city is in a river valley, I never enjoy myself quite as much as on a lazy summer day at the flat field.

So, after being firmly bitten by the electric bug and familarizing myself with the details that go with electric power, my mind started to wander back to the Rosenthal 1:3.75 scale Discus/Ventus fuse that's been in my shop for about 3 years now.

Scale ships have to be the most perfect candidates for electric conversion out there. They usually need immense amounts of nose weight to balance anyway, which can be lead...or Ni-Cad's. Though a prop on the nose of the model is definitely the easiest way to do things, it does mean that the model can't ROG...thus eliminating the freedom that comes from not having to have another person around.

Anyways, long story short(er), I'm electrifying my 199" span Ventus. I came into a Graupner up&go through a trade for an open-class sailplane, and working at a hobby store gave me access to good pricing on a drive system. Though I have a LOT of work ahead of me in scratch-building the airframe, I enjoy that...and Calgary has a fairly long building seaon most years!

Thus, specs should be:

WS: 199", four piece, carbon spars, with carbon cloth over foam
Weight: 15-16lbs...I think that's possible based on other projects
Motor: Hacker B50-22XL, 1:1 through Graupner Up&Go
Battery: 26 GMVis cells in custom pack
Controller: Hacker Master 48 Opto
Prop :10x5, 17,500 rpm by MotoCalc est.
Expected climb rate: 620 fpm @ 39 amps
Last edited by SoarNeck; Feb 11, 2003 at 12:22 PM.
Feb 11, 2003, 12:17 PM
RCGroups Author
SoarNeck's Avatar
Here's a shot of the fuse. Cutting out the opening for the drive bay doors really's a nice fuse, and that's a big hole! In the end though, the result will be worth it.

As you can see, only the retract install has been started. I'm still not sure whether to hard or shock mount the retract...have to see how ambitious I want to be.
Feb 11, 2003, 02:18 PM
Registered User
Lenny970's Avatar
Originally posted by SoarNeck

Scale ships have to be the most perfect candidates for electric conversion out there. They usually need immense amounts of nose weight to balance anyway, which can be lead...or Ni-Cad's. Though a prop on the nose of the model is definitely the easiest way to do things, it does mean that the model can't ROG...thus eliminating the freedom that comes from not having to have another person around.

Some very good points, but don't assume that a nose mounted motor means that assistance is required for launching.

Last year I converted a 4 meter Duo Discus to electric quite successfully, and have recently followed that with a conversion of a 6.6 meter (22 ft) all molded Nimbus 4. Power is a nose mounted Hacker B5011XL, 6.7:1 on 30 cells. All up weight is 21 pounds. With the prop blades painted white, they are only visable on the ground.

Handlaunching this beast is out of the question. I ROG from a grass field using a short, but strong bungee. I get instant airspeed and about 10 feet of altitude, at which point the motor is switched on and the model climbs away. I get 3 or 4 good climbs to altitude with this setup.

Look for this model at MWE this weekend! Hope I can find enough room to assemble it!

Lenny Keer
Feb 11, 2003, 11:36 PM
Registered User
Do you have anymore info on your bungee launch method? How long? Where does it attach? Picture?
Feb 12, 2003, 12:22 AM
Registered User
Lenny970's Avatar
No, I don't have any pictures. I'm using the 25 foot bungee rubber that was once sold by Holliday, and now by Aerofoam. Here's the website:

The standard bungee is good for my 11 pound Duo Discus. The 21 pound Nimbus needs the Mega bungee. I use a fixed towhook located on the bottom of the fuse, about the center of the canopy. Exact posititon isn't critical.

Multiplex makes a nice bungee release pedal that makes is easy to launch.

Feb 12, 2003, 12:29 AM
around Colombia
ShredAir's Avatar
For more info on large electric-powered gliders, also see this thread:

Dieter Mahlein
Feb 12, 2003, 01:25 AM
Registered User

Simprop Solution XL


the Solution XL is one of the best gliders in the 4m class. Mine climbs with only 12 cells very well up.
Loops, negative loops, rolls, all is possible. Landing with butterfly is very easy.

My XL:
12 x Sanyo RC2400
Kontronik KBM52-18 3,7:1
Max. current about 50A
Kontronik BEAT 55-6-18
External BEC
Aeronaut 17 x 11
4 x HS81, 1 x HS81MG (rudder), 1 x 11mm Noname (elevator)
Total weight: 4450g

Feb 12, 2003, 07:37 AM
Registered User

Thoughts-more info. on launching

Thanks to Ernst for posting the information on his Solution XL. I would encourage others to list successful large glider/motor combinations that have worked well. My 4 meter Krause Discus(non-electric) weighs about 12 lbs. with retactractable wheel. Ernst' electric Solution XL weighs only 10lbs! Thank god this fantastic machine is not readily available in the USA - as my RC threatened marriage would most certainly suffer another damaging blow! Still I want one- are there any to be had in the USA?

I downloaded a fantastic video showing Dave Wenzlick's 5.3 meter Nimbus(12 lbs) being easily hand launched. I believe it was powered with 20 cells. Climbed with authority. Flew great!

Years ago Joe Enhui brough a 6 meter EMS Nimbus to Elmira with a motor in the nose. It was successfully hand launched and flew very well.

From our relatively rough aerotow field, John Derstine was able to easily take off from a dolly with EMS Sperber, 20 cells, 12x7 prop-direct drive.

So it appears large gliders can be launched successfully by hand, bungee, ROG(up and go), or powering off a dolly.
Feb 12, 2003, 09:25 AM
(Batteries not included.)
Dave Wenzlick / Slickraft's Avatar
Originally posted by Lenny970
{snip}....6.6 meter (22 ft) all molded Nimbus 4. {snip}Look for this model at MWE this weekend!
Hope I can find enough room to assemble it!

Lenny Keer
San Diego MWE bound too...
I'll make room next to mine Lenny. I'll just make the space a little bigger as my 1/5 scale Nimbus 4 only consumes 5.3 meters of real estate.
My Nimbus needed a little TLC after flying it at Francis Peak last summer when I blew off a spoiler blade on the backside of a huge loop, but it's ready to go again. I loved seeing your Nimbus 4 fly in Phoenix a few weeks ago but I didn't get any pics. Excellent flight! Maybe we should enter the LMR event on Sunday?

Feb 12, 2003, 09:57 AM
Registered User
Hi everyone,

Just got a friend who has bought a second hand Solution XL as new in the box. He also wants to convert it to electric power. Has anyone any construction photos or building tips for it? He only has the instructions for it in German. Has anyone got any English instructions?

Many Thanks

Last edited by Cones; Feb 12, 2003 at 10:00 AM.
Feb 12, 2003, 11:02 AM
Registered User

Another great example

Thanks to Dieter for posting the link to an excellent discussion of the succesfully electified RnR SbXC. With it's large fuselage, this is a natural for stuffing in batteries. The S2048 is a fast airfoil that should like the extra weight. Best of all it is available and built right in this country!
Feb 12, 2003, 01:21 PM
Registered Lifeform
Paul Willenborg's Avatar

The other SbXC!

Hi Dieter and everyone,

Here is the other SbXC mentioned in Dieters thread. Scott was nice enough to let me do the test flights on his plane, and it is fantastic!! I've been meaning to start another thread about it for some time.

We did have some issues with the dolly in the deep sod farm grass, and it ended up with significant modifications before working well. After eight flights we are now getting easy, consistent take-offs.

The XC is an incredibly good flyer, fast, thermals well, lands easy, and does an awesome slow roll! Can't recommend it too highly.

This picture is lifted from the video of the first takeoff. I'll post details of the setup if there's interest.

Feb 13, 2003, 11:57 AM
I plant balsa sticks too
luc's Avatar
You can see pcs of my ASW22BE vario of 3m85 (electrified)
and my NImbus 4D of 5m20 (electrified) on my home page (see link at bottom, lots of pics)
Last edited by luc; Feb 27, 2003 at 04:03 PM.
Feb 24, 2003, 07:33 PM
Registered User
Lenny970's Avatar
Some nice photos and video were shot by Joe Nave at the MWE of my 6.6 meter E-Nimbus 4. They can be seen in the Video Gallery and 2003 Photo Gallery at

Interesting to see the wing flex during a loop and hear the sound during a high speed low pass.


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