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Old Jan 08, 2007, 01:44 PM
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STERLING FS-36 CORSAIR e-CONVERSION!

Hi Guys!

I just bought this FS-36 Corsair kit (Old Sterling Kit) and I have been busily building away on it... I will post pictures as soon as possible ( I have lots, but haven't gotten around to posting them yet...).

If anyone has done this conversion before, what motor/prop/batts did you use?

I bought this kit for $10 from an estate sale, lucky, I know as they go for aot more than that...

Anyway, this kit is suprisingly nicely cut considering the age.

Equipment I am planning on using:

AXI 2808-16 Outrunner (Just one I happen to have)
9x3.8 APC Slowfly Prop
3s 1250 Lipo (Thunderpower)
CC 25

I am fitting it with 3 hardpoints, one under each wing (on the rudder channel, so you can release them independently) and 1 under the belly for a torpedo. Which, hopefully will be a functional one that will run just under the surface... have to built that after..

Anyway, any thoughts or pointers are appreciated!

Cheers,
Marc
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Old Jan 08, 2007, 04:39 PM
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How's the wood density in the kit? I'd be thinking about lightening the airframe as much as possible, especially aft of the cockpit. Every Sterling kit I ever built was built like a tank, with heavy wood.

What glow engine was this designed for? It is a 1/2A design, right?

Rick
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Old Jan 08, 2007, 11:06 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
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Marc

I know this airplane by reputation only, but like Rick says- it was not a light design. You're way undergunned in terms of power- I suspect that you need closer to 300 watts to fly this airplane- it really needed a 0.15 glow engine- a TD .049 wouldn't hack it. Hence a slow flyer 9 x 3.8 prop isn't gonna work either-

My recommended power system would be a Jeti Phasor 15/4 (or equivalent) an 8 x 6, a 3s 35A comfy pack - probably around 3000-4000 mAH. Don't run a pack at 20C, you may need lots of throttle to fly this airplane- it will be quick- so you want to have some flight time. If you build it light, might be pretty sweet.

Sam
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Old Jan 09, 2007, 11:21 AM
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Wow really?

Wow... Really? Hmm. Interesting. I have been building away and the fuse seems light enough, but the wing seems really heavy to me. I have not sheeted it yet, though I have on the fuse in 1/16th. I was thinking sheeting hte wing with 1/32 to save a bit. The wood wasn't too bad as far as density, though I have replaced some of it. I am curious to see what the weight of the airframe will be when it's all together without covering or equipment. Maybe my axi won't be enough.

I wanted to run a 3 blade prop on it, when a prop says 9x7 , does that mean the diameter of the circle is 9" and the pitch of each blade is 7? That's what I am assuming. How to I convert between the 2 and 3 bvlade props... Any thoughts? a 9x7 must be like a 10x8 or so 2 blader?

Anyway, I will post pictures tonight. Thanks for the input! Keep it coming!
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Old Jan 09, 2007, 11:51 AM
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Judging from some of your questions, you appear to be a beginner to R/C, or nearly so.

I would recommend you not try to fly this airplane unless you can comfortably handle a fast, heavily wing-loaded warbird. Even if you build it light, it's going to be a handful to fly, no matter what. Don't kid yourself--it's definitely not a plane for a beginner or inexperienced pilot.

Rick
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Old Jan 09, 2007, 01:53 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
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Marc

Agree with Rick. Also- you probably do want a rudder on this airplane.

In terms of wing sheeting- I wouldn't go to 1/32 simply for handling reasons. This is gonna be around a 2 lb airplane if I'm guessing right and that means that landing is going to have some impact loads. 1/32 will be annoying.

In terms of props- yeah, you're about right- a 3 blade 9 x 7 (and yes, 7 is the pitch) is about a 10 x 7 two blade. However, this is going to be a fast airplane- you'll need a pitch speed of at least 60 mph- hence an 8 x 6 turning at 10k rpm min.

Sam
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Old Jan 09, 2007, 02:28 PM
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I have the same kit lurking in my kit closet. I think it was intended for a .10 glow. The AXI may have enough urge on a 2200mah 3S lipo maybe 9x7 APC E prop. I would recommend using rudder with landing gear for ROG takeoffs. You might want to use one micro servo for each aileron and a Y harness to the receiver.Use a 3amp speed control such as the current Phoenix 25. With total four servos on 3S lipo you may want to use a Park BEC. Agree that this is not a beginner's model, you should fly a couple of GWS foam warbirds to get some slower low wing aileron experience before attempting to fly the much faster heavier snappier Sterling Corsair
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Old Jan 09, 2007, 08:53 PM
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Haha... that's funny...

Haha.. That's funny... I suppose given my past post (reading it back to myself) you would assume I am a beginner. Actually, I have been flying for about 15 years, anything from 3D profile planes, ducted fan jets (glow), warbirds of various sizes, float planes and 2610 scale combat etc... That's ok though, my posts were dense, I realize...

Anyway, I will just chug along and finishe her up, if she ends up being a "just for show" model that's ok too. We'll see what we end up with.

So far, it feels light enough (she is a warbird afterall) and I will get a weight measurement once I finish the sheeting on the fuse. Get an idea of where were going.

Thanks for the input though, I do appreciate all the wonderful people on rcgroups that add their input, it helps alot when doing things you haven't done before...

Cheers!
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Old Jan 09, 2007, 10:32 PM
Use the 4S Luke
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USA, TX, Euless
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You can always weigh the parts then post here. I just weighed some LHS wood - 1/32" X 4 X 36 15grams
Lone Star Balsa same size 9grams.
It is quite possible or balsa to rance 4:1 in weight.
When I was a kid, my dad built a Sterling P-38 and with 2 Fox 15's it flew great. It would loop on one engine.
I found a Sterling P-38 kit about 5 yrs ago and put 2 OS 15's on it. It is fast but will only fly straight on one engine. It glides like a brick. I called dad and he said "Those Sterling kits were fameous for using oak-hard balsa. I substituted lighter balsa and that's why ours flew so well."
Now he tells me!
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Old Jan 10, 2007, 01:56 AM
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Quote:
Originally Posted by soaringtuna
Haha.. That's funny... I suppose given my past post (reading it back to myself) you would assume I am a beginner. Actually, I have been flying for about 15 years, anything from 3D profile planes, ducted fan jets (glow), warbirds of various sizes, float planes and 2610 scale combat etc... That's ok though, my posts were dense, I realize...
No offense was intended.

The question about prop size and pitch designation just struck me as a newbie question, that's all. I guess I just don't quite understand how anyone could be flying R/C for for that long and not be extremely familiar with how props are sized and marked.

Rick
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Old Jan 10, 2007, 08:13 AM
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just a followup to feather's comment on balsa density.Before I was placing large orders for balsa for kits (where I can add in some specific grades from the supplier with the standard order), I would take a gram scale in to the hobby shop and select wood using it. I remember the numbers from one sortie when I was getting sheeting for my OV10 bronco. They'd just gotten a large shipment of 1/16X3X36 and I needed 10 or 12 sheets of it. After 20 minutes or so of weighing, and placing into various stacks, and selecting what I wanted, I found out that those sheets ranged from 11 grams to 63 grams (yes, same size sheets). Compared to the kit-supplied wood, I saved just over 8 ounces on the wing sheeting alone by spending 20 minutes at the hobby shop with a gram scale. They used to laugh at me when I did that, but no more <G>
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Old Jan 10, 2007, 09:10 AM
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Balsa weights

Sounds good guys, I will weigh some of the balsa sheets are see how it's doing. I compared it with the light stuff I picked up from the LHS for my Lanier Shrike (found their sheeting on the heavy side) and found that it was about equivalent. Not sure on weight, I will find out.

About the prop thing, I have never used a 3-bladed prop since I never had a reason to, so that's why I was just checking to see if there was a fast and easy conversion so I can think in the way my mind works with props. I know about 2 bladers, as to what prop should give me what range of amps on which motors, but three bladers, my mind would just want to increase the total by 33%. Just thought I would ask

Anyway, glad to hear the P-38 flew ok! I expected it to be a brick, and I am sure it will be! haha. In the end, if it has to be gas, I suppose it might be so, I have a OS .25 sitting around that I guess I coulod install...
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Old Jan 10, 2007, 11:17 AM
Use the 4S Luke
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Gary - When they see me at the LHS, they ask if I'm gonna need the scale. I use theirs. And yes they are stilll amused.
But my 75" Edge weighs just over 9lb.
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Old Jan 11, 2007, 07:38 AM
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Wow feather, that's amazing!

I've posted pictures on my website of the build, you can see it along side my guillows' stuka converison also. Both are coming along, but I should really focus on one or the other to finish them up! Oh well...

http://www.limagraphics.com/planetma...S36/index.html

Here's my Stuka Thread:
http://www.rcgroups.com/forums/showt...=2#post6710938

Cheers to everyone!
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Old Jan 11, 2007, 09:44 AM
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And just think if the design of that edge was given as much consideration as the wood. My 90", 1660 square XL's are 9 and a touch with ubec and 7S, almost 10 lbs with 10S and 5-cell 3000 nimh rx pack,... .. without any thought given to wood selection,..just whatever was grabbed out of the stacks.Unless I run large packs, and the big 5 cell 3000 rx pack, they get too light to snap or spin. I don't get the amusement anymore at the hobby shop, as i rarely select wood there since I place very large wood orders for kits and short kits. I just add in some 4 to 6 lb wood to the order and the work is done for me by lonestar.
Just remind the hobby shop that you get the last laugh when you finish the plane at ridiculously low wieght. The OV10 I mentioned above ends up 7.5 to 8 lbs with two 25 glow engines and 4 ounce tanks. Mine had two geared electrics,.. twenty 2600 nimh cells (10 per side), 7 servos, and pheumatic retracts. Mine flew at a shade under 6.5 lbs with 800 watts. That plane was de-commissioned a few years ago and sits in the attic. I've ran the numbers and with some A30's and lipos I should be able to shave 1.5 to 2 lbs off it and have more power to boot. I just haven't gotten around to doing it yet.

Quote:
Originally Posted by feathermerchant
Gary - When they see me at the LHS, they ask if I'm gonna need the scale. I use theirs. And yes they are stilll amused.
But my 75" Edge weighs just over 9lb.
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