RE: Great Planes Combat Corsair and Mustang

RE: Great Planes Combat Corsair and Mustang
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RE: Great Planes Combat Corsair and Mustang - 2/26/2008 11:02:29 PM

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Joined: 10/18/2006
From: Auckland, NEW ZEALAND
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Hiya frednjess

This thread has been great for those building one of these fantastic planes. Your not going to regret the rudder mod. I did it and am pleased I did.

As for the servos - I would save the hassle of skids and just mount the servos on top. It is sooo easy to do. Takes about 30 minutes longer than mounting them underneath.

What I did was to use a pin and push it through the top sheeting from underneath, using the corners of the ply servo tray as a guide. This gave me a rectangle on top to cut out which matches the servo tray cutout. Then I placed my servo in this cutout and marked out how far forward and back I had to extend the hole to clear the servo mounting lugs. Then I cut 2 short lengths of 1/4" sq hardwood and glued them with 5 minute epoxy down on top of the servo tray to screw the servos to. The thickness of these blocks may vary depending on what servos you use.

At this point, mounting on top is exactly the same as mounting underneath.

When you remove the covering to glue the belly pan on, keep the covering that comes off. It comes of cleanly with gentle application of a heat gun. I used pieces of this covering to cover the servo holes in the bottom of the wing.

It's worth noting that skids underneath only slightly reduce the chances of stripping a servo by preventing the servo arm from catching on anything. There is still the control horn on each aileron hanging down there just waiting to grab the ground and rip those servo gears to pieces.

(in reply to frednjess)

RE: Great Planes Combat Corsair and Mustang - 2/27/2008 12:32:07 AM

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Joined: 2/12/2007
From: La Vista, NE, USA
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Thanks for the idea Longdan. Unfortunately, I've already got the wings put together with the servos installed...Guess I should have asked my question a few days ago. I've been playing with the idea to use something similar to what the glider guys use, covering the entire servo arm, pushrod, and the front of the control horn. Might work.
My other idea was to use the extra horsepower and fly a high alpha approach about 6 inches off the deck and shut her down right in front of myself. Seems to work alright with my 3D foamies.

(in reply to longdan)

RE: Great Planes Combat Corsair and Mustang - 3/15/2008 7:16:35 PM

root

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From: Manasquan, NJ, USA
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Use HS 81MG's...

or really go for broke with the HS 85MG's....

the METAL GEARS are strong enough to take the grass landings.

Many other GP Corsair owners have been successful with this as a standard/necessary modification.

The servos are more expensive but worth the extra $$.

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RE: Great Planes Combat Corsair and Mustang - 3/16/2008 8:51:58 AM

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From: Auckland, NEW ZEALAND
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My Corsair ate dirt today

I was flying it around quite nicely with a APC 9x6 prop, and as usual, it was fast. I thought I would see if I could slow it down by putting a MAS 10 x 4 prop on. I launched it, and, even with the engine screaming at full revs, it struggled to get up any flying speed. It sort of lurched around a bit, never more than 15-20 feet off the ground. and it was very unresponsive to any control inputs. It eventually dropped a wingtip and spiralled into the dirt. I managed to shut off the motor before it hit.
I thought it was going to be matchwood, but the only damage was a broken prop (of course), broken wing mounting lug and cracked cowl. Not too bad I thought. Could have been much worse.
I would have thought that the 10x4 would haul it up to flying speed quite easily. Not so. There was nothing wrong with the way the engine was running. In fact, it was probably revving a bit higher than with the 9x6. It just didn't want to fly.
So once I get it fixed, I'll know not to use fine pitch props on it.

(in reply to root)

RE: Great Planes Combat Corsair and Mustang - 3/16/2008 2:25:38 PM

root

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LD,

That's very sad news AND very unusual.

Whenever I use more diameter there's always more thrust capability resulting in more pull - especially on take off.

Did you adjust the needle valve to compensate for the larger prop??

Anyways, I'm glad to hear of the minimal damage.

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RE: Great Planes Combat Corsair and Mustang - 3/16/2008 8:53:01 PM

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I retuned the engine after switching props. I don't tach the engine, just tune by ear.
The 10x4 was a master airscrew, with big paddle-like blades, whereas the APC finger slicer only has thin tapered blades. Not sure how much difference this makes. But it definitely flew better with the coarse pitch APC.
I was very surprised at how it just didn't want to climb out with the 10x4.
I know that my Corsair is at the upper end as far as weight goes (1320 grams, 46.5 oz), but as I said, I had no problems flying it with the 9x6.

(in reply to root)

RE: Great Planes Combat Corsair and Mustang - 3/18/2008 12:14:35 PM

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From: Newark, DE, USA
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Is there any possible way that the 10 X4 was mounted backwards? I did that once and the results were just as disastrous as yours!!

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RE: Great Planes Combat Corsair and Mustang - 3/18/2008 10:08:22 PM

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quote:

ORIGINAL: Arebeck

Is there any possible way that the 10 X4 was mounted backwards? I did that once and the results were just as disastrous as yours!!

After seeing you mention this, I went and checked, as the broken prop is still on the plane. But it is on the right way.
Someone told me that MAS props aren't very efficient at high rpms, so it could be something to do with this.

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RE: Great Planes Combat Corsair and Mustang - 3/20/2008 10:00:31 PM

root

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longdan,

I used a 10x5 APC and had plenty of pull.

You might just try the 10x5 APC --that's if you aren't too paranoid due to the last CRUNCH---

10x4 is a tad too low in pitch according to the usual 1st number up 2nd number down rule.

FWIW, I did use a MAS 9x6 on my Combat mustang in place of a broken 9x6 APC due to not killing the motor during the belly landing (no landing gear installed) and it was noticeably slower.

I also used a APC 9x4 on my little Ace Ultimate w/ OS 15CVA at first because of thrust insurance rising of grass and it took off in about 10 feet as opposed to the present APC 8x5 which takes more like 25 or 30 feet to ROG.

I hope this gives you a better idea/choice.

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RE: Great Planes Combat Corsair and Mustang - 4/13/2008 2:48:34 AM

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From: La Vista, NE, USA
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I've been building other stuff for awhile, so the Corsair has been on the back burner. Over the last two days though...I'll be ready for a maiden tomorrow as long as the weather holds. I did figure out a good way to overcome not using metal gear servos. I found sailplane servo covers from Hobby-Lobby. They are towards the bottom of the following page, listed as long aileron pushrod fairings, $3.70 for the pair. Here's the link:
http://www.hobby-lobby.com/servomount.htm
These should cut down on any linkage induced drag and I'll probably paint them gray to match the belly pan. I'll try to post pics tomorrow, as my wife took the camera this evening.
Wish me luck on the maiden!

(in reply to root)

RE: Great Planes Combat Corsair and Mustang - 4/13/2008 3:11:57 AM

root

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I can see how they cover the rod but how do they or can they cover the servo arm??

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RE: Great Planes Combat Corsair and Mustang - 4/14/2008 2:54:15 PM

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Well, here''s the maiden flight video. I didn''t even notice the hiccup on launch until I saw the video. Great flight, although a little short. Ran out of fuel after about 3.5 minutes. I think we lost a lot trying to get her started. Had to hold it nose high to keep fuel from pouring out of the carb. Otherwise, great flight! Can''t wait until I''m done with the engine break in so I can add a little more speed!

http://www.youtube.com/watch?v=MxWBU5BXSPc
Here''s a pic of the servo covers, worked great!

Attachments

Click to see fullsize image.

Click for fullsize

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RE: Great Planes Combat Corsair and Mustang - 5/4/2008 8:14:24 AM

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From: eugene, OR, USA
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would it be possible to put standard size servos in it?

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RE: Great Planes Combat Corsair and Mustang - 5/4/2008 1:58:39 PM

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Worms,
Yeah, you could put standards in. It would require some hacking, though. My experiment here has actually worked pretty well. You can't see the covers in flight and the servos are still in good shape. I've got 6 flights so far.

(in reply to ilikeworms0o0o)

RE: Great Planes Combat Corsair and Mustang - 5/4/2008 11:14:16 PM

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From: Melbourne, FL, USA
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I just picked up a couple of small planes (.25 size) and believe one is a Great Planes combat P-51, not sure. I put a OS FX .25 on it, 9X4 prop and had about 5 hand launched flights with it this weekend so far. After a little dip it picks right up and flies where I point it for a longer flight than most other larger planes. I was able to keep up with a Viper 500 Rossi .45 powered plane today and know 9X4 is holding it back. The turns slow me down a lot. Should I try a 8X6 or 9X5 from here? Mousse can? Plane weighs 2 lbs 6 ounces. I also enjoyed the Global ME-109 with the same engine, but it's a lot slower, and weighs a pound more. But for a small plane, without thinking about combat events, I enjoy them more as daily fliers than I expected, being used to .40 and .60 size pattern and stick type planes for the last ten years.

(in reply to frednjess)

RE: Great Planes Combat Corsair and Mustang - 5/13/2008 4:06:46 AM

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