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Sep 07, 2019, 02:36 PM
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Discussion

1/4 midget (.15 size) electric setup


I picked up a Stafford P51 1/4 midget kit and want to do it as an electric. Id like it to be just a little faster than the Cox or Rossi .15s we used back in the day. Just checking to see if anyone has done this and what their setup is. Thanks, Jim
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Sep 07, 2019, 04:31 PM
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DHG did one some time back, an eflite 6-series inrunner. Not sure what he used for batteries, esc, prop, but you might check with him. It was one of his Stinger airframes that previously had rossi or conquest or nelson power
Sep 08, 2019, 09:13 PM
WBE
WBE
White Fang
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Found this post from Duane.

DHG's AvatarDHG , 07-12-2010 12:24 PM
RE: Electric Setup for QM15
Brad,

Long time no see! Just spotted this. I made a successful conversion of one of my QM15 Stingers (it last flew in 1992, been gathering dust since then) using the setup taken straight out of my upgraded Stryker. The components are:

MOTOR: E-Flite Six Series brushless, 28 mm diameter, 2700 KV rating
BATTERY: Common Sense R/C 3S1P x 2200 mAh lipo
ESC: Great Planes Electrifly SS-45 Silver Series
PROP: APC 6 x 4E

I had to slide the battery as far forward as possible, but with the long nose on that airplane (typical, since they all were designed around those light .15 glow engines) the CG came out OK. The all-up weight was exactly the same as before, 40.5 oz. With the prop turning at 24K, the speed and handling are just about like what I remember with the Nelson .15 except much quieter of course. If Jerry Small hadn't invented EF-1, I'd be lobbying to race this sort of thing locally.

Cheers,

Duane
Sep 09, 2019, 01:24 PM
DHG
DHG
Kinetic Sculptor
Yep, you found it. Also user "leo turt" did an electric conversion using the EF1 powertrain. See post #664 and following under this thread:
https://www.rcgroups.com/forums/show...5#post35665628

Cheers,
Duane
Sep 13, 2019, 10:21 PM
c/f
c/f
Registered User
Just an FYI I am running an OS EF1 motor in a small Mustang, using Graupner ESC and real time in air voice telemetry of all metrics, RPM,Current,Volts,ESC temps.

Using a 2400MAH Hyperion G8 HV 6s battery Ive run 3 different props.
APC 8X8, Master Airscrew 7X6, Graupner 8X5.

8X8 to much for motor. had to govern MAX throttle to 60 amps and 15500,rpm, esc 150deg
7X6 is 53amps @ 21,500rpms, 143deg on ESC
8X5 is 47amps @ 24,700rpms 110deg on ESC

I got some Graupner 8X5.8 coming. Should be just right............

Another setup going in this same model next is a SNEU custom inrunner Steve targeted my specs of turning a 7X7 on 6s @75amps,
Latest blog entry: Amt 180
Sep 18, 2019, 11:27 PM
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That telemetry is a great idea .
I bought a 9x9 e prop i was going to cut down to 7x9 to see if it would make the Tony a bit faster .
But I got off on several tangents and haven't got to it yet .
One was to rebuild a Shark and wedge a EF1 in it as well.
And an Estrellita is next on the list .
So we can race them .
My MArk 111 Rossi with pipe used a 6x10 so im thinking a shorter prop with a bit more pitch than 8 might be the ticket .
Len
Sep 23, 2019, 08:52 AM
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Thread OP
Thanks forgive great info. Im going to use the same EF1 motor. Leo, what esc, battery and prop are you running? We used to use top flight 7X5 paddle blade props and modify them so there is not much prop clearance. Thanks
Sep 24, 2019, 10:14 AM
Registered User
https://www.rcgroups.com/forums/show...-Maiden-Flight
Its here i tried to copy the pic and paste it with my phone but failed

I just used what was recommended by E flight .
The battery is pushed as far ahead as possible it balanced .
The battery fr E flight is discontinued but others are available .
Sep 26, 2019, 12:18 PM
DHG
DHG
Kinetic Sculptor
Len,

I really like that mounting system! It never occurred to me to thread the holes in the mount tabs, but that eliminates the need to fish around in there installing blind nuts. Looks like you do have to fish around from the front to put the bolts in, but you could do that before the firewall was glued in so you could move it around a little. Then after the motor was firmly bolted to the firewall, apply epoxy from behind to secure the firewall to the fuselage sides. There would be no need to remove the motor after that (not normally, anyway), so the limited access to the bolts wouldn't be such an issue.

Jim,

These airplanes were designed for 7" props, so you might need to bend down the landing gear struts another 1/2" or so for an 8" prop ... or just throttle up slowly on your first takeoff and let Nature take its course. The length would tend to adjust equally on both blades.

Cheers,
Duane


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