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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Chuck_Smith on December 25, 2012, 03:48:07 PM
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I'm drawing up the semi scale MB 339 (ish) stunt ship and it's time for propulsion decisions.
Point of reference I'm a big ST .46 fan. My planes tend to be 630 in^2 plus/minus the wingtip treatment.
The dilemma with this design is that being a "jet" the nose fairly skinny up front. That means an IC installation will require either an exposed clylinder or a sidewinder install. Neither is conducive to running a piped engine (not a .46 in this case) which would be my first choice. So the next logical design iteration is to go electric.
Looking at the Hacker A30-10KL as a possible choice. RSM packages it with front and rear mounts whick is attractive. 900KV gives me 13000 RPM to work with and it's rated for 30A constant and 42 max. I'm leaning towards a 4S battery but 5S is on the table too.
Questons:
Ideas on how it would work at 50 oz?
How much cooling does it need?
Anybody using one a similar sized airplane? How does it work?
Chuck
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My Cobra-Es are about 630 sq in and run the Hacker A30-10XL. Running on 4 cell. Weight is 59oz on the take apart (with battery)
and 55oz on the non-take apart. Running about 8900 RPM with the APC 12-6EP. Really like the motor. Have not had any issues with it.
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hi
that sort of sized model im running an OS 3825-750 and a 5s3000 on a 12x6 pusher 9450 revs at 56 ounces max weight .
paul
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I am flying a couple of the A30-10XL motors on 4 cell batteries. I find them to be both powerful and reliable, can't ask for much more.
Andy
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Another way to look at it: 900kv means you pretty much are locked-in to 4S, for 5S you want to be around 700kv.
Next step: folks are using that motor with a 12" prop, that size prop "fits" the size of your bird. Personally I'd opt for a 12x4.5EP (clipped down from a 13") turning about 9800 RPM - give or take a little.
I dunno Chuck, I think you gotta just BUILD IT! y1 8)
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I dunno Chuck, I think you gotta just BUILD IT! y1 8)
Got that right. If I pull this off right it will be really neat. I printed out a full-size set of plans for Dave Ree's F5 and I'm not going that radical on the "droop snoot". I'm building this one fixed, but if the concept works I's like to do one with retracts if I can keep the weight under control. Face it, an electric jet with the wheels up would scribe some beautiful lines in the sky.
Of course, my REAL target is an electric, twin ducted fan A10. If you look at it, it just works from a design standpoint. My fear is that it needs to be HUGE to get the wing loading and thrust-to-weight ratio right, but the technology is moving pretty fast. Maybe in a few more years,
Didin't one of your clan do a Fouga back in the 70's? I seem to remember one. Maybe it was the whole V-tail thing.
CHuck
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My Electrajet used a Hacker A30 10 XL,, it was about 650 inches of wing and 65 ounces,, The Ice light 50 amp ESC died mid flight for some reason,, but I saved the plane, it was flying well until the wind was stronger than my line tension in the overheads,, alas, the Hacker is not working so well now,, its kind of egg shaped,, 4S 4000 mah packs with reserve I used the full 13x4.5 APC EP prop
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Didin't one of your clan do a Fouga back in the 70's? I seem to remember one. Maybe it was the whole V-tail thing.
CHuck
That was me. For the reasons you stated (smooth nose, no chin scoop), I want to do an E-version or two. Maybe one for Nos-30 and a second with long wing, tip tanks & retracts.
(Will have to supply napkins for onlookers to wipe the drool from their chins...)
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That was me. For the reasons you stated (smooth nose, no chin scoop), I want to do an E-version or two. Maybe one for Nos-30 and a second with long wing, tip tanks & retracts.
(Will have to supply napkins for onlookers to wipe the drool from their chins...)
Heck yeah! That would be sweet. Pass the wet-wipes.
Tip tanks are definately going on the MB 339. That was one of the "must haves" when I was picking a planform.