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Feb 14, 2005, 07:44 PM
Registered User
Rave

Sureflite P-39 Airacobra Conversion


Here is my second Sureflite conversion. The power system consists of the following:
Jeti Phasor 30-3 brushless motor
APC 11X7E prop
Castle Creations Phoenix 45 ESC
Thunder Power 3S2P 4200 Lipo pack
AUW is 4.2 lbs

I am impressed how well this big bird flies. Here are a few pictures.
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Feb 18, 2005, 09:40 AM
Registered User
Very nice!! I have one in my garage I started a couple of years ago, but it was going to be a slimer. I could never get the finish nice enough so now it sits amounst the other half finished planes. Your's looks great!!
Feb 18, 2005, 01:43 PM
Registered User
Thanks SteveO, but I have to tell you that the front 2/3rds of the fuselage was covered with 1.5oz glass cloth.
Feb 18, 2005, 03:33 PM
Speed Demon
GregG's Avatar
Joe Papa, that looks terrific! I've always liked the sleek looks of the P-39. You've really done it well. I hope to see it fly one of these days. Do you fly at RSA?

BTW, is that cowl half plastic and is that the way the kit does it stock?
Feb 18, 2005, 04:54 PM
Registered User
I fiberglassed my entire plane with .75 glass and water based Poly. The frustrating part is how easily it is to still put a dent in it even with that coating. Maybe soon I'll dig it out and finish it. With a little paint it might look better. Right now it's just in primer.
Steve
Feb 18, 2005, 06:13 PM
Registered User
Greg, the half cowl you see is actually foam. I have one of the older Sureflite kits I bought from the previous owners before he retired. The new P-39 kits from Sureflite come with a plastic cowl that covers all the way around. It has a flat firewall. I have only flown this model at the local school/field near where I live because I am familar with the surroundings.


SteveO, I used .75oz cloth and WBP on my first Sureflite conversion. It's a Cesna 182 with working flaps. I too was not impressed with the "scuff resistance". This time I went with 1.5oz cloth and Tap Plastics marine grade epoxy. This will give you the type of "finish" you are looking for. A few ounces of extra weight really doesn't make a difference on a plane of this size and power.
Mar 09, 2005, 05:27 PM
a really nice guy, really
Ralph Brekan's Avatar
What!!! You didnt put th motor BEHIND the cockpit?!? THATS NOT SCALE! LOL!
Mar 09, 2005, 05:32 PM
a really nice guy, really
Ralph Brekan's Avatar
So is there a way to power planes this size on a 2s1p pack? (just kidding). I have one TP2100 pack I guess I should get a second and one of those pack bridges the sell to make serial packs parallel. Does anyone know who sell one with deans connectors?

I'm building the Sureflight P40 Is the power system listed at E-Flightline good enough for these birds. I was thinking AXI2820/12 but then I'll have to go 4s2p for sure...
Mar 14, 2005, 08:57 AM
OCD: Old, Cranky and Disgusted
challenger_i's Avatar
I thought the AXI 2820/12 was a hummer on a 3s pack. But, then again, I have been playing with lighter wing loading planes.

Note to Steve: If that P-39 is taking up too much space, I'd entertain the idea of helping you get it out of the way!
Mar 14, 2005, 09:59 AM
Registered User
Longarm's Avatar
kamikazi,

I converted one of the P-40s and I got the equipment from E-Flightline. I went through several combinations before one worked and E-Flightline kept working out the bugs with me until we got it right.

I ended up with a Mega 16/25/2 motor with a Phoenix 45. I have a 3s2p pack with the 2500 Tanic batteries and it flys very nicely. I toss mine because I didn't want to buy retracts for it. I belly land it and I have had no problems with the plane. The only thing I did was paint it. I didn't glass anything. Flys great.

E-Flightline is the way to go in my opinion. They have great customer service.

Longarm
Mar 14, 2005, 08:54 PM
Registered User

Now complete with split flaps!


Here are some new pictures of the Airacobra with split flaps. They really help to haul down this plane for easier landings. I no longer have to come in faster than 25 mph.
Mar 15, 2005, 12:26 PM
100% electric since 1990
twest's Avatar
I converted one of these back in 1994 following MEC's directions. I used a "war emergency power" (remember those?) brushed motor on 9 1700 round cells, 6:1 'superbox', and a 13-7 yellow folding prop. No landing gear, just an underhanded toss. The plane flew on about 300 watts at most, so it would have been underpowered by today's standards. Oh, and fitting a direct-drive motor sure looks easier than putting an MEC superbox in the nose.

It flew fairly well, and I'm sure yours really 'zips'.
Mar 15, 2005, 12:26 PM
a really nice guy, really
Ralph Brekan's Avatar
Thats awesome! Thanks for sharing that flap mod! So the flaps use two servos? No retracts on this one right? That makes six servos if you use two for tail and four in the wings. WOW! Thats some bird you're building.

How much slower do flaps make her go? Like 15mph landings? Does it inhibit a tipstall? I'm thinking one of these Sureflights on a geared Endoplasm (or sp500) would be fun. No where near BL or gas; but more like a big GWS plane. The cost of BL motors and controllers this size are prohibiting me from going over 48".
Mar 15, 2005, 05:43 PM
Registered User
Kamikazi, my split flap setup uses only one servo through two cables. If I had to guess at the incoming landing speed now, I would say about 15mph is pretty close. I found that if you use too steep of an angle for the flaps, the plane becomes very unstable at slow speeds. I think about 30 to 40 degrees is about right. No I don't have any retracts on this bird, but maybe the next one will(Sureflite P-40 Warhawk). Here's a picture of the servo setup in the wing.
Mar 15, 2005, 06:58 PM
a really nice guy, really
Ralph Brekan's Avatar
Joe that is sweet! You guys definately are encouraging me. Sounds like 30 degree flaps would be enough to create sufficient drag w/o completely spoiling airflow (tip stall). I'll start saving my pennies to convert a SF P-40. Due to economics, I'll probably start out w/a brushed 500sp motor similar to what Great Planes put in the Super Sportster EP ARF. If they can fly the SSEP on that setup; these Sureflight kits could fly just as well. And if you put a 16t truck motor in there on a GP600 gearbox even better... Direct Drive BL (although lighter) takes some expensive (heavier) packs, (ie the ones I dont already own). Could there be more than one way to skin the cat?

Thanks again for all these awesome images; great food for thought.


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