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Author Topic: P-40 ARF (Electric) issues  (Read 1895 times)

Offline Mike Alimov

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P-40 ARF (Electric) issues
« on: December 28, 2018, 04:00:26 PM »
I started putting together a P-40 ARF for my kid, to replace the crashed Cardinal.  First impressions were positive; mostly in the sense that all parts were fairly straight, and the control surfaces were pretty stiff; decent covering quality.

After re-hinging the wing and tail with pinned hinges (replacing stock CA hinges), I dry-assembled the entire plane to determine preliminary CG placement.  This is where things got disappointing.  To balance the plane, it required a monstrous motor: Cobra 3520, which comes in at a whopping 7.5 oz.  I was originally planning to use the same 4.4 oz Rimfire that used to power the Cardinal.  This is an increase of 3 oz, resulting in a tentative all-up weight of 54- 55 oz, way more than I was hoping for.

Has anyone put a P-40 ARF together, and how did you resolve these issues?

Offline Kevin Muckleroy

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Re: P-40 ARF (Electric) issues
« Reply #1 on: December 28, 2018, 04:54:37 PM »
Mine Ready to fly weighs 55.5oz
Mine balances perfect with the Brodak BH-2076 2826/3548 @ 6.5oz and Brodak BH-1892 4s x3500 @9.5oz and landing gear install backwords for propeller height.
60' .015 lines
APC 11 x 5.5 prop

Offline Mike Alimov

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Re: P-40 ARF (Electric) issues
« Reply #2 on: December 28, 2018, 05:44:09 PM »
And how does it fly at 55.5 oz weight? (This is over 14.5 oz/in^2 based on my calculations)

Offline Kevin Muckleroy

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Re: P-40 ARF (Electric) issues
« Reply #3 on: December 29, 2018, 02:43:47 AM »
Flys Great
Heres Shug flying his

 

Offline Shug Emery

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Re: P-40 ARF (Electric) issues
« Reply #4 on: December 29, 2018, 06:46:31 AM »
Flys Great
Heres Shug flying his



It is a real good flyer. Mine is around 55 ounces as well.
Shug

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Offline Chuck_Smith

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Re: P-40 ARF (Electric) issues
« Reply #5 on: January 06, 2019, 04:30:20 AM »
I was gifted a glow version and spent a couple nights assembling it. It would have been un-flyable if built with the supplied parts.

1) CA hinges were replaced with quality hinges

2) The kit came with centered horns instead of the correct offset horns required.

3) The pushrod joiner - looked like it was made out of 316, (wasn't magnetic either) and couldn't be used to make a solid, airworthy solder joint.

Yeah, it's small stuff and not big deal for an experienced builder, but for a newb it would have resulted in a less than optimal experience.

Overall impressions:

Decent building job, excellent covering job.

Design - seems overall very nice and well thought out except the little flap fairing thingy is a real design flaw. It adds nothing and overly complicates the control system.

I'd say the biggest thing is an obvious quality control issue with the supplier who puts in the wrong hardware. The plane would un-flyable with the horns provided as the elevator pushrod would hit the flap when giving down elevator. Fix that, give good hinges and then I'd say it's a decent value.

Weather has not been conducive to a test flight so no PIREP but I've seen them fly before and they appear to be capable little planes with happy owners.

Chuck


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Offline Phil Spillman

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Re: P-40 ARF (Electric) issues
« Reply #6 on: February 05, 2019, 02:24:42 PM »
Two new P-40 ARF's assembled down here in Virginia both powered or to be powered by LA .46's. One finished and flown last Sunday without any advanced trimming flew absolutely great right off the board! Stunted quite well with no Bad Habits! I think that this new kit is much better than the old ones and they weren't any slouches! Mike, if wait is too much of a problem...go IC and enjoy that great sound of a four cycling two cycle engine! You remember the 2:4:2 break don't you? Sweet!!!!!!!!!!!!!!

Phil Spillman
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Offline Chuck_Smith

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Re: P-40 ARF (Electric) issues
« Reply #7 on: December 02, 2019, 05:04:34 PM »
Followup on the P40 ARF

Trimmed as well as possible it can fly a passable pattern. Started to get aggressive on the squares, second corner of the outside square the bellcrank mount came loose with the expected results.

Rebuilt with 1" dihedral (each side) to move leadouts to vertical CG, differential flap travel  Dihedral looks bitchin' and gives it a much nicer stance.

Chuck
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Offline Chuck_Smith

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Re: P-40 ARF (Electric) issues
« Reply #8 on: December 14, 2019, 05:31:48 AM »
Had requests for pictures, sent a PM to one with the rebuild sequence. Not for beginners.
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Offline Perry Rose

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Re: P-40 ARF (Electric) issues
« Reply #9 on: December 26, 2019, 06:38:07 AM »
Any ARF can use a better bellcrank installation. Post sticking out of the wing top and bottom with a plywood strip glued over them. Even the SV 11 benefits from this mod.
I may be wrong but I doubt it.
I wouldn't take her to a dog fight even if she had a chance to win.
The worst part of growing old is remembering when you were young.

Offline Chuck_Smith

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Re: P-40 ARF (Electric) issues
« Reply #10 on: December 31, 2019, 10:06:42 PM »
Any ARF can use a better bellcrank installation. Post sticking out of the wing top and bottom with a plywood strip glued over them. Even the SV 11 benefits from this mod.

I this case it was poor building by the mfg. There was only enough glue to tack the parts into place, and questionable wood used. I talked with the person who designed the bellcrank mount and the design is sound and tested if quality parts and  workmanship are used.
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