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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Motorman on November 04, 2015, 09:09:41 PM
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I've never made a built up fuselage before but it looks like Balsa/ply sides are the main strength of it. I have an electric conversion box made for the kit I have, made from 1/8" lite ply. I can see from the motor mount back to the back of the box it's very strong but there is not much to connect that strength to the wing. It's like a built in shear point. Shouldn't the sides of the battery box wrap around the leading edge and extend back to the bellcrank mount?
Thanks,
MM
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MM:
Typically the fuselage doublers run aft to about the highpoint of the wing - that is good practice for IC or electric. The next key is to distribute the motor mount load into the doublers. Long beams do a good job for IC airplanes, for electric you should integrate or reinforce the motor mounting plate to the doublers & surrounding structures. One potential problem when converting kits is that the doublers often stop 1" or so short of the nose ring. If you are using a FRONT mounted motor you will likely want to make new doublers at least as far as the motor mount.Rear mounts usually end up somewhat forward of where the F1 normally goes, so the install is usually friendlier.
The doublers are more than adequate to perform as the sides of the battery box, Assuming that the doublers go past the wing LE as described above then you are in good shape. The battery tray(s) of course need to be secured to the doublers and (preferably) the FI & F2 bulkheads.
For further explanation, I attached a couple pix of the new conversion I designed for the Brodak Gypsy. The conversion features new doublers with tab/slot design to integrate the front-mounted motor mount, F1, F2 and the battery tray. This is very robust AND lighter than the IC installation - not a bad trade!
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Walt:
The pictures kind of look like what you got in your kit don't they. As long as they work it does not matter who manufactured them.
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Look at that!
Turnkey solutions for electrifying designs ... and nicely done too, Dennis.
E-Stunt is certainly maturing.
take care,
Dean P.
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I've never made a built up fuselage before but it looks like Balsa/ply sides are the main strength of it. I have an electric conversion box made for the kit I have, made from 1/8" lite ply. I can see from the motor mount back to the back of the box it's very strong but there is not much to connect that strength to the wing. It's like a built in shear point. Shouldn't the sides of the battery box wrap around the leading edge and extend back to the bellcrank mount?
First, yes, there ought to be doublers back to the wing.
Second, the higher you climb up the stunt ladder, the less the airplane designs look like they'll withstand a minor crash or even a hard landing, and the more they look like every gram is devoted to making a stiff and stable structure. So build the thing, and don't crash!
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Dennis,
Nice looking structure. Looks strong and light. H^^
Could have helped me out when I did the "IC to the big "E" conversion awhile back to the ARGO.
Oh well, maybe next time.
Keep up the good work.
Charles
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So the plywood doublers form the sides of the battery box. How thick is that plywood? My box has extra 1/8th ply pieces on both sides. So I guess they're not needed?
MM
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So the plywood doublers form the sides of the battery box. How thick is that plywood? My box has extra 1/8th ply pieces on both sides. So I guess they're not needed?
The best place for the heavy bits is still in the wood bin when the plane flies.
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So the plywood doublers form the sides of the battery box. How thick is that plywood? My box has extra 1/8th ply pieces on both sides. So I guess they're not needed?
MM
The Gypsy set-up shown in the pix is 1/32" ply on 1/8" balsa fuse sides. Not seeing exactly what you have. my guess would be that adding 1/8" ply to that would be unnecessary weight UNLESS you are also using it to reinforce the firewall/motor mount. If that is the case then consider cutting back the 1/8" ply until you are left with just a motor mount reinforcement. Pix below are from the Vector Conversion kit. It is design as a rear mount with the motor poking through the firewall. The piece with the three holes (first pix) is glued to the fuse side ahead of the firewall and forms a step to reinforce the firewall joint. Depending on how your fuse goes together you can achieve the same thing with the balsa "cheek-blocks" that most kits use for the carving stock behind the nose ring.
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Dennis
I started a Vector and I don't get how the top hatch comes off for battery access.
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Dennis
I started a Vector and I don't get how the top hatch comes off for battery access.
Hi Daryl
Sorry for the delay, had to find the fuse & take some pix - see below - please advise if this is what you were looking for.
The hatch is just a removable section of the top block between the motor mount (F1) and F2. It has plywood caps fore & aft and the hatch must have about 1/32" gap in the fore/aft direction so it can pivot up and out. The front of the hatch has a tab that slides into a slot in F1. The back of the hatch Should use either magnets or a pin style latch as shown here. The one shown here is home made: the wire slides in plastic tubing and there is a magnet buried in the top block to pull/hold the pin in the latched position. Also, HobbyCity sells a nice spring latch.
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I got it now thanks Dennis.