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Old Feb 02, 2013, 05:23 PM
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Joined Feb 2013
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Best way to fix the C of G on this plane.

I know alot of people were having problems with the CofG on their aircraft.
I seen solutions offered in this thread, like the dime soution.
However I personally found that adding weight to such a small aircraft was not for me. It added weight and relly effected the performance and flight time.
I also did not want to have to add the mustang propeller to solve the power issues from extra weight, besides it would still use more energy this way and I like my 3 bladed prop.

So what is the great solution I speak of that can magically fix your plane?
While I made a video of what I did to fix mine.

How to Fix C of G on Parkzone Ultra Micro F4U Cosair (3 min 17 sec)


As you can see there is a bit of modification required, but it won't cost you any extra parts either then a very small elastic.
You can also use a small peice of scotch tape at the front of the cowling to hold the end of the battery in as well if you do not want an elastic on the cowling for looks. (I later switched to the tape method.)

Also this method is relly good because you can find out how far up to move the battery for the c of g on your plane. I had to move mine to the end, but if your battery does not have to go up that far just draw a small ink dash where the end of the battery should be. The velcro should hold it in place so it won't slide.

So sit back and enjoy my video on fixing this.
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Old Feb 02, 2013, 07:37 PM
Flying, crashing, (re)building
Australia, QLD, Brisbane
Joined Aug 2012
165 Posts
Whistler, I fixed mine by taping an Australia 5 cent piece to the nose... granted it does weigh a few grams but I didn't notice it having any serious effect on the flight times. Aside from the CG problem, I found with the 3 blade its just too slow and seemed to lack airspeed, making flight in light breezes very challenging. Once the two blade mustang prop went on the thing was like a different plane...

Having said this, the rubber band is a good idea - I have had the battery dislodge from my corsair waaaay too many times as the velcro isn't terribly tight, and it will often come lose during extreme aerobatics (hehe). I've become a bit of an expert at flying with the battery dangling like a pendulum, but since the last time it did it I've resolved to fix it good n proper.
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Old Feb 03, 2013, 02:10 AM
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Originally Posted by Elwood74 View Post
Whistler, I fixed mine by taping an Australia 5 cent piece to the nose... granted it does weigh a few grams but I didn't notice it having any serious effect on the flight times. Aside from the CG problem, I found with the 3 blade its just too slow and seemed to lack airspeed, making flight in light breezes very challenging. Once the two blade mustang prop went on the thing was like a different plane...

Having said this, the rubber band is a good idea - I have had the battery dislodge from my corsair waaaay too many times as the velcro isn't terribly tight, and it will often come lose during extreme aerobatics (hehe). I've become a bit of an expert at flying with the battery dangling like a pendulum, but since the last time it did it I've resolved to fix it good n proper.
I might give the 2 bladed prop a go for even more zip, but I honestly found the 3 bladed prop sufficent. It probably is needed for that extra zip to pull that coin through the air :-p
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Old Feb 04, 2013, 11:39 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
3,169 Posts
Quote:
Originally Posted by TheWhistler View Post
I know alot of people were having problems with the CofG on their aircraft.
I seen solutions offered in this thread, like the dime soution.
However I personally found that adding weight to such a small aircraft was not for me. It added weight and relly effected the performance and flight time.
I also did not want to have to add the mustang propeller to solve the power issues from extra weight, besides it would still use more energy this way and I like my 3 bladed prop.
A 2 bladed prop is unquestionably more efficient, and the micro Corsair is a good test platform to prove it. As you mentioned in your video, the stock wheels are too small for use on rough surfaces. I made my own 1" diameter wheels out of epp foam and rubber band treads. With those I can successfully land on rough pavement and frozen snow.

To take care of the CG, I am using 250 mah Hyperion batteries that were designed for the MCPx helicopter. They are mounted in about the same position as yours, except that no velcro, tape, or rubber bands are required. I made a cover out of dinner plate depron, that allows the battery to be simply slid into position.
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Old Feb 05, 2013, 10:23 PM
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United States, TX, San Angelo
Joined Mar 2004
298 Posts
Hopefully I'm not out of line with an additional power question for the micro F4U. I had a little bit of a crash the other day on landing (likely due to the tail being a little heavy) so it came in nose first from about 2 feet up. It flies just fine still but I'm now having a problem with the motor. It seems that when I put my throttle at about 2/3 the motor isn't running smoothly...what I hear is a slight pulsing as if I were throttling up and down slightly, so it doesn't run smooth. Also after only about 2-3 minutes if I put the throttle up to full the motor cuts out completely (almost as if I've hit the LVC) but the battery isn't nearly run down yet. I've tested the batty with a multimeter and it seems to be just fine, so I'm wondering what's causing the motor to have these issues. The only thing I can think is that the prop shaft is bent and the motor is working too hard? Does that sound possible? I've looked closely and the shaft doesn't seem wobbly. I did notice though that the prob doesn't sit completely straight forward because the gearbox is tilted slightly to the right. But I figured that was intentional.

So yeah I know I listed out 4 different things there but I'm having trouble diagnosing what is causing the erratic motor behavior. Any guidance would be greatly appreciated. Thanks!
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Old Feb 05, 2013, 11:59 PM
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Rancho Cucamonga, CA
Joined Sep 2006
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Quote:
Originally Posted by Gizzmo0411 View Post
The only thing I can think is that the prop shaft is bent and the motor is working too hard? Does that sound possible? I've looked closely and the shaft doesn't seem wobbly. I did notice though that the prob doesn't sit completely straight forward because the gearbox is tilted slightly to the right. But I figured that was intentional.

So yeah I know I listed out 4 different things there but I'm having trouble diagnosing what is causing the erratic motor behavior. Any guidance would be greatly appreciated. Thanks!
I experienced the same symptoms with my micro P51 minus the "rough" landing, HH sent me a new motor. Removed & replaced it & it's worked fine ever since. There was something going on with the gears, like the prop was "pulling" the gear away from the motor?? Whatever it was the new motor fixed it.

Good luck, I hope somebody else chimes in with a better solution.
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Old Feb 06, 2013, 07:45 AM
Flying, crashing, (re)building
Australia, QLD, Brisbane
Joined Aug 2012
165 Posts
I would almost be willing to put money on the motor too... I drove my Corsair into the ground from about 50-60 ft up (it was my first time attempting inverted flight with this bird and I had a dumb thumbs moment ). It basically went vertically into the ground, nose first and I was able to cut the throttle very shortly before impact.

The airframe was mostly ok (except for cracking a previously glued part of the wing) and had a few scuffs, and at the time everything seemed normal so I stowed it back in the box. A couple months later I went to fly the corsair again and noticed that the motor was pulsing, much like it does when LVC activates, but I was on a freshly charged, known-good battery. I tried another battery and had the same result. Bought a new motor from the states and is noticeably quieter and seems smoother. I should also point out that I probably had several dozen flights on the old motor so the brushes were probably somewhat worn already. I didn't need to replace the gearbox, it seems perfectly ok. I did put a small drop of 3-in-1 oil on the gears to try to keep them lubed but I don't know if its needed.

The good thing is that the brushed motors for these things are quite cheap to buy. The bad thing is that they're a bit of a pain in the butt to swap out. Regarding the angle of the prop, yes it should have some thrust angle built into nose/gearbox for the prop - it should not be dead parallel to the nose of the plane and if you do replace the motor you will need to make sure its close to being the same as before. Mine wasn't due to the slightly crinkled nose but I was able to adjust it and coax it back into shape.
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Old Feb 06, 2013, 12:23 PM
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United States, TX, San Angelo
Joined Mar 2004
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Thanks for the tips. I wonder if there's a good brushless option for these things? I haven't searched through this whole thread but has anyone tried swaping out the stock motor for a brushless one? I know the ESC would need to change also, but that might be a worthwhile swap. Are there any good outrunners that are small enough for these things? In the meantime I'll see if I can pick up a spare motor from Horizon...great that these motors are so cheap now. Even 5 or 6 years ago they were much more expensive.
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Old Feb 06, 2013, 01:20 PM
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Southlake, TX
Joined Jan 2008
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Quote:
Originally Posted by Gizzmo0411 View Post
Thanks for the tips. I wonder if there's a good brushless option for these things? I haven't searched through this whole thread but has anyone tried swaping out the stock motor for a brushless one? I know the ESC would need to change also, but that might be a worthwhile swap. Are there any good outrunners that are small enough for these things? In the meantime I'll see if I can pick up a spare motor from Horizon...great that these motors are so cheap now. Even 5 or 6 years ago they were much more expensive.
Direct Drive brushless motors aren't as efficient as the Geared Brushed motors, so Run times will suffer for the same battery size/performance.
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Old Feb 28, 2013, 05:42 AM
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United States, FL, Vero Beach
Joined Feb 2011
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I've listed my Corsair here in the RCG Classifieds for just $40 plus shipping.
Although it flies fine (and has the "Dime Mod") it's being sold for the electronics, since the wings have been cracked several times and the nose is wrinkled a bit.

If you put a new wing on it, you'd have an F4U UM for cheap.

Anyway, just a heads-up...
http://www.rcgroups.com/forums/showt...0#post24276229

Thanks!
Mac
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Old Mar 05, 2013, 08:00 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
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ESC Problem?

Last week I started having trouble keeping the motor running. At first it would go for a couple of minutes and suddenly quit. Then it gets progressively worse. It will run for ten seconds and quit. Then it will just spin for a split second and quit. There is no problem with the batteries, because they work fine in the little Mustang.

Today I replaced the motor on the Corsair with a new stock one. The Mustang is on it's third motor but the original one in the Corsair has given me great service. It took off like a bat out of hell and I am confident the motor is ok. Then it suddenly quit and went through the same routine as before. I'm thinking there is a problem with the ESC. Any ideas?
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Old Mar 05, 2013, 08:37 PM
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United States, WI, Merrill
Joined Jun 2011
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Originally Posted by Jovanx View Post
Last week I started having trouble keeping the motor running. At first it would go for a couple of minutes and suddenly quit. Then it gets progressively worse. It will run for ten seconds and quit. Then it will just spin for a split second and quit. There is no problem with the batteries, because they work fine in the little Mustang.

Today I replaced the motor on the Corsair with a new stock one. The Mustang is on it's third motor but the original one in the Corsair has given me great service. It took off like a bat out of hell and I am confident the motor is ok. Then it suddenly quit and went through the same routine as before. I'm thinking there is a problem with the ESC. Any ideas?

It's a tiny geared, brushed motor, on a lighter than air, (almost) airframe. The servos are suspect for many people, but not in this case of motor power. Look at your choices. Is that gear drive a bit sick? How many grams of weight have been added to fix that "little" crack in the wing or tail? Putting in a new motor, are you sure you do not have any kind of parts touching/binding each other in a different way than they should?

If none of that works, try a new brick. This is not a cheap hobby and flying Micro sized planes is almost Brand New! How many UMX planes do you and your friends or club have?

I am getting the impression that the Corsair that I thought was so darn cute, and you must have too, may just be a little weak for giving a long lasting and relaxing flying experience. It was built as light as it could be and 2 times with the CA to fix a little crack here or there can put it over the top.

You can troubleshoot til your brain fries, but I have been a little concerned at the number of these up for sale in the classifieds.

Hmmmmmmmm...........

just a thought

John in Merrill
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Old Mar 05, 2013, 09:52 PM
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United States, OR, Portland
Joined Jan 2008
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I took the brick out of this plane and put it in a microaces kit plane. Might try getting one of those $20 AR6400 clones and stick it in the F4u fuselage just to see if it works ok. Wouldn't mind being able to fly it again even if I do like what I transplanted it into better!
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Old Mar 06, 2013, 11:57 AM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
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Originally Posted by seeingeyegod View Post
I took the brick out of this plane and put it in a microaces kit plane. Might try getting one of those $20 AR6400 clones and stick it in the F4u fuselage just to see if it works ok. Wouldn't mind being able to fly it again even if I do like what I transplanted it into better!
Maybe that is a good option, as I am pretty sure it is a problem with the ESC. I don't want to give up on this plane because it flies so well (once I finally got the CG right). This plane has been a frustration for many people and it also frustrated me at first, but now I love the way it flies.
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Old Mar 07, 2013, 02:24 AM
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Originally Posted by Jovanx View Post
Maybe that is a good option, as I am pretty sure it is a problem with the ESC. I don't want to give up on this plane because it flies so well (once I finally got the CG right). This plane has been a frustration for many people and it also frustrated me at first, but now I love the way it flies.
You could also just plug in a small brushless (or brushed?) ESC into the AR6400 and switch it to external ESC mode to rule out the ESC being the issue. It is very simple to switch the AR6400 over to that mode. I BELIEVE its hold left stick in the upper left corner when powering on and wait for the blue light to blink quickly after about 5 seconds, but you should confirm that if you try it
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