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I just got the plans and short kit for Goldburg’s Sailplane from Bob Holman
and plan on an electric version for my winter project. Looks like I am going to have to get a bigger workbench. Anyone have any experience with this model either gas powered or electric, any helpfull hints or suggestions would be appreciated.
Ed
Hi Ed,
I’m not sure quite how big the Sailplane is, but I know it is big. Most
would consign such a model to class B but I want you to know that
recent battery tests indicate that there are large nickel metal hydride
batteries that would make the big buzzard go like hell in class A. Read
the thread in this forum on NMH batteries for class A. If you build
an electric Sailplane I’d use Lipos for class B, and 6 of the large Elite
NMH cells (2200 or so) for class A. There are many who would want
to modify the rules to avoid such super A ships, and I think I agree
with them, but it would be very interesting to see such a thing work.
The Sailplane has a great reputation and history, and its forte was
its glide. I’d build it to have a wing loading a little lighter than the
ignition version. Don’t forget to light the fuse!Chuck
Chuck, sorry to be so late with the repy, but the sailplane has been on hold while I built a Lanzo stick for Old Timer Rubber. I am building the Sailplane to SAM rules which has a weight rule of 8 oz/sq ft of projected wing area, thus the plane will have a minimum weight of 64 oz (4 lbs)
They also have a battery rule based on weight, for the 64 oz model it is
1500mah max. Jim has suggested the AXI 2814/10 motor. I have not selected batteries or prop yet and with my limited (none) experience with electric I can use alot of help.
EdEd, It sounds like the bottle neck in your power system is the battery. Is there a limit on voltage? Good lipos will discharge at 20c so a 1500 mah will get you 30 amps. If you can use a 3 cell pack this is your best option in my opinion:
http://www.modelmotors.cz./index.php?page=61&product=2217&serie=9DPG&line=GOLD
Look at the sailplane option with the 15 X 9 prop.
What is the goal of the class?Ok guys I am going to come out of the closet here. My name is Ed and I am going to fly this model in the rc old timer soaring events. Jim, the battery rule for SAM events is: The battery shall consist of seven NiCad or NiMh cells or two LiPoly cells with a manufacturer’s capacity of no more than 100 mah per ¼ lb of model All Up Weight (AUW; weight ready to fly with battery). 90 second motor run, 10 minute max. Total of two flights for final score. The rule for the AMA event is: the battery pack is limited to a maximum 8.4 volts nominal of any battery type. 60 second motor run 8 minute max total of 3 flights for final score. The problem with the AMA event is it’s flown the same day as F1B at the NATS so I don’t know if I can get them both in or not.
EdEd, My wife was standing over my shoulder when I opened your last post. Funny. I have a better understanding of what you are trying to accomplish. With the weight and power restrictions you will not see high performance but it sounds like fun. Your power system will need to be geared. I will do some research.
I would like some suggestions as to prop size for the electric sailplane.
The power will be an AXI 2814/10 with Jeti 70 amp controller and seven cell Sanyo CR-1300-SCR batteries. I will try to attach a picture.
Thanks,
Ed
Hey ED,
10 X 6
http://www.modelmotors.cz./index.php?page=61&product=2814&serie=10&line=GOLD
Nice looking model. Can you use a folder?The trip was exellent. Scott Lapriak traveled with us. Scott flew 1/2A gas to a second place finish droping the third round and I put up 8 maxes with the Maverick on Nimah power to win Electric A. Chuck Groth was the only other electric flier.
The glider event looks like fun. I hope to see it fly this summer.
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