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Old Dec 02, 2011, 07:01 AM
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Jennik's Avatar
Czech Republic, Prague
Joined Sep 2009
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Vintage Sparky electric conversion

Hi guys.

Before I have completely finished my rubber motor Sparky model and saw it flying (even without the fuselage covered), I realised I just can't resist to try to convert it for radio control, thus electric powered.

The thing is, I don't know what engine/prop would be best to use.

It must be very light as the model now has about 75 grams now (!) even though it's 103cm wingspan. Counting in the covering tissue and some construction strengthening and control surfaces modifications I guess the weight without equipment shouldn't exceed 100 grams.

Sparky would really look nice with a larger propeller, possibly 8-10'' so it seems it would need motor with gearbox to pull such prop.

I'm decided to buy all the equipment on hobbyking shop as I found theirs stuff is good price/performance/quality ratio and low shipping cost. So if anyone would be so kind to suggest the equipment it would be much appreciated, thanks!

Model specs:

Wingspan: 103 cm / 41 inch
Weight w/o equipment: appx. 80-100 grams / 3-3.5 ounce
Desired prop diameter: 20-24 cm / 8-10 inch
Desired maximum motor diameter: 2.8 cm / 1.1 inch
Desired motor mount: behind firewall (inside)
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Last edited by Jennik; Dec 02, 2011 at 08:52 AM. Reason: typo
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Old Dec 02, 2011, 01:44 PM
Stantheman
LaGrange, Ky.
Joined May 2004
431 Posts
I don't have a recommendation for the plane....but that picture of your daughter holding it is priceless! Make yourself some copies and put them away so that you can preserve the memory. They grow up so fast........
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Old Nov 28, 2014, 10:58 AM
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Jennik's Avatar
Czech Republic, Prague
Joined Sep 2009
15 Posts
I just found this thread of mine realizing I didn't updated it for a "little while" (3 years)

So, for anyone still interested, I finished the model successfully with the rubber motor and actually flew it briefly. Well, it rather glided only. I didn't glued the rudder and elevator permanently as I planned conversion to electric flight. I was also afraid that full unguided flight was too risky and the model would have easily get damaged.

Then I started the conversion. Put two servos inside, the receiver and battery and ESC. But I struggled with the electric motor. The firewall turned out to be very fragile and small to safely support engine weight, vibrations and torque.

Finally, lot of changes in my personal and professional life had changed as well and I had to put my models aside for a while.

So, the recent status is: well, stand by... The model is lying in a box and waiting for it's big day. Hopefully, it's coming next summer

I have attached some pictures illustrating the progress done so far.
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Last edited by Jennik; Nov 28, 2014 at 11:35 AM.
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Old Nov 28, 2014, 07:39 PM
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Bruno Stachel's Avatar
Edgewood, KY (Cincinnati)
Joined Jan 2004
192 Posts
That's a beautiful model Jennik. Great pictures.

Bob Holman Plans sells a 41" RC version of the Sparky. (A short kit.) I had one, but never got around to building it. I wish I hadn't sold it now.

Subscribed and standing by.
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Old Nov 28, 2014, 08:11 PM
Kimbers Keeper.
Joined Nov 2014
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Old Nov 29, 2014, 05:09 AM
Registered User
USA, PA, Westmoreland Co.
Joined Aug 2008
1,361 Posts
Pat Tritle has a Sparky kit although his model has a 55" ws.
Here is the thread
http://www.rcgroups.com/forums/showthread.php?t=1024923
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Old Dec 04, 2014, 07:50 AM
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Jennik's Avatar
Czech Republic, Prague
Joined Sep 2009
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This is really nice picture! How old is it?
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Old Dec 04, 2014, 10:12 AM
Kimbers Keeper.
Joined Nov 2014
116 Posts
Quote:
Originally Posted by Jennik View Post
This is really nice picture! How old is it?
If you are referring to my post, 1955.

I was helping Mom at the church rummage sale and found the camera, bought it for
a nickle, it had film in it, went home and took the picture. Thirty five cents to have
it developed. This was the beginning of a fifty year career as a freelance photographer.

The camera looked like this;

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Old Dec 04, 2014, 02:31 PM
yank and bank!!
Joined May 2013
2,491 Posts
Realistically, at the very least the nose area is going to have to strengthened to accommodate the motor.

Honestly, with a 40" wingspan I would sheet the front half of the fuselage with 1/16" balsa for rigidity and to contain the battery and esc.... but that's just me.
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Old Dec 08, 2014, 04:02 PM
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Jennik's Avatar
Czech Republic, Prague
Joined Sep 2009
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Quote:
Originally Posted by failboat View Post
Realistically, at the very least the nose area is going to have to strengthened to accommodate the motor.

Honestly, with a 40" wingspan I would sheet the front half of the fuselage with 1/16" balsa for rigidity and to contain the battery and esc.... but that's just me.
I have used very thick paper as a cover and it's quite firm and resistant on most places. The most weakest part is the place where you place your thumb and index fingers while throwing the airplane into the air. I plan to strengthen this one as well.

For the motor, there just wasn't much place to attach it to. So I think I'm going to cut the first two formers, then glue a plywood firewall to them and attach the motor from the front. I know, It's not very elegant idea, but as I mentioned, I want it fly one day - so I must do compromises.
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Old Dec 08, 2014, 04:22 PM
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Jennik's Avatar
Czech Republic, Prague
Joined Sep 2009
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Quote:
Originally Posted by BHOFM View Post
If you are referring to my post, 1955.

I was helping Mom at the church rummage sale and found the camera, bought it for
a nickle, it had film in it, went home and took the picture. Thirty five cents to have
it developed. This was the beginning of a fifty year career as a freelance photographer.

The camera looked like this;
Wow! I used to be photographer as well, even studied it. My first camera given by my father was this one. That's why I always incline to B&W and square format. Perhaps, my story just happened a couple of years later then yours, because this camera of mine, made in late fifties, was already antique when I got her in middle 90s
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Old Dec 09, 2014, 12:29 AM
Kimbers Keeper.
Joined Nov 2014
116 Posts
I know we are getting a bit off topic here?? I followed the F1 cars for several years. (17)





When I moved in 1999 six boxes of pictures and negatives were either taken from the apartment
or truck and forty years of work was gone. twenty years of racing history.
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Old Dec 09, 2014, 04:06 AM
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Jennik's Avatar
Czech Republic, Prague
Joined Sep 2009
15 Posts
I don't mind being slightly off topic for the moment Once I make some progress on Sparky I'll bring the topic back on tracks

Nonetheless, that story of yours is pretty sad... That's one of advantages of digital photography: easy to backup. I myself have thousand plus negatives and can't imagine loosing them... What are you doing these days?
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Old Dec 09, 2014, 05:13 AM
Kimbers Keeper.
Joined Nov 2014
116 Posts
This was pre digital. 35mm, 2 1/4X2 1/4 and 5X7. I retired from the photography game in 1997.
Worked as an OSHA inspector for several years and then as a part time teacher, custodian and
retired for good in 2008. Now I ride bicycles, build, fly RC and row and sail. I did work with the
team that did the graphics for the History Channel show Dogfights. Still have all the software
and flightsim.



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Old Dec 09, 2014, 09:59 AM
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Jennik's Avatar
Czech Republic, Prague
Joined Sep 2009
15 Posts
Quote:
Originally Posted by BHOFM View Post
This was pre digital. 35mm, 2 1/4X2 1/4 and 5X7. I retired from the photography game in 1997.
Worked as an OSHA inspector for several years and then as a part time teacher, custodian and
retired for good in 2008. Now I ride bicycles, build, fly RC and row and sail. I did work with the
team that did the graphics for the History Channel show Dogfights. Still have all the software
and flightsim.
Nice to meet such a veteran of everything I like as well I spent some time with games when working in Bohemia Interactive for 6 years. ARMA series, Take On Helicopter and other games. Wonderful job it was, really. But one day, I had to move on.

Used to play simulators a lot, even as a "virtual airline" pilot. But once I tried airplanes for real, while training for license as a glider pilot, virtual flying lost some of it's beauty for me, I'm afraid. I even tried helicopter and acrobatic plane. Wonderful.

So, while working hard to save some money for real flights, I'm building these little to stay in touch with the sky...
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