c.g. balancing 1400mm corsair

[bagger]

Greetings all. Just purchased my 2nd 1400mm Corsair. On my first one, I didn't use the battery compartment because I needed to add 4 ozs. of weight to the tail. I made a tray and glued it right behind the compartment and was able to get the proper balance by moving the battery.

On this new Corsair I want to use the compartment. Has anyone had trouble balancing this plane using this compartment? I don't want to add weight to the tail or stick a tray in again. Any help is appreciated. Thanks.

[boomer108]

RE: c.g. balancing 1400mm corsair

Are you talking about the FMS 1400 Corsair?

[bagger]

RE: c.g. balancing 1400mm corsair

Yes sir. How did you balance yours?

[OV10]

RE: c.g. balancing 1400mm corsair

Hello bagger
You balance it inverted with gear retracted. I have the Olathe version and the CG is at 95mm with a 4000mAh 4S in the pocket with no additional weight required. It flies very nice with both the drop tanks and rockets on board with about 4% up elev trim on my DX8. Want to give you a heads up that that this thing will land hot n heavy unless you have full 30 degrees of flap. Using 15 degrees to take off is ok but if you use the same amount to land it will be hot, that is because the wing chord is not as wide as similar in this size birds like the Hellcat, Mustang, Warhawk or even the Trojan.

[bagger]

RE: c.g. balancing 1400mm corsair

Thanks Charlie. I'm using a Admiral 3000mAh 4S. That's what I was using in my old 1400mm Corsair. It flew ok with it. I also leave off the drop tanks because I mount a DV Fly camera there. Going to run with rockets after I get them painted. Will be working on the c.g. this weekend. Thanks for your tips.

bagger

[boomer108]

RE: c.g. balancing 1400mm corsair

Welcome to the forum!

 I used the manufactures recommended 110mm from the leading edge with the gear extended and with the battery in the nose pocket it balanced fairly nose heavy. I added 1 ounce of wait to the tail and that puts me slightly nose heavy which is fine for a war bird. Like you I also tried putting the battery back in the main compartment with velcro and a strap and just moved it to balance where I wanted it, but I would rather it be in the nose pocket. I have also read other people claim the 110mm is wrong and should be 95mm from the leading edge,but I have to believe that a plane that's been around for a while and with Motion RC flight checking planes the way they do that would have been corrected. So I believe the 110mm from the leading edge to be correct. I also use the Great Planes CG Machine, great tool. Hope this helps. Good flying and I'm back to the Black Hawks.
Roy B.

[bagger]

RE: c.g. balancing 1400mm corsair

Thanks Roy. Will be working on it this weekend.

[boomer108]

RE: c.g. balancing 1400mm corsair

I forgot to add I using a 3000 30c lipo and my bird is Big Blue.

[ryramZ]

RE: c.g. balancing 1400mm corsair

I'm surprised anyone would need to add weight to the tail. In the vid we flew with 3600 and 3000 all the way forward. I felt as if she were almost tailheavy on the 3000 battery. Not to any detriment. Really only thought so on approach. Had to make concerted efforts to not let her nose come up too much. On 3600 settled in great. 4000 fit however i have not flown the corsair with one.

[bagger]

RE: c.g. balancing 1400mm corsair

Using a Admiral 3000mAh 4s battery installed in the battery compartment I went to balance my 1400mm FMS Corsair.  I have a Great Planes C.G.machine so setting the rulers at 110mm I set the plane on the machine.  It was so nose heavy it wouldn't even stay on the machine.  So while trying to transfer some weight to the rear of the fuselage, I managed to break my motor mounts and have to buy a new fuse and cowling now.

Anyway, this is what I found in the front of the fuse.  These 2 very heavy weights.  If these are in the new fuse, I'm going to take them out and try balancing the plane that way.  Just thought I'd throw this in and show the folks that have tried to assist me in this process.  Thanks to all.

bagger

[boomer108]

RE: c.g. balancing 1400mm corsair

Hey Bagger!

That's pretty much what I found when I originally went to balance mine. What I found was I initially had the GO machine set out to far on the wing. The wing tapers in and that will cause the 110mm setting to be off. So I found setting the pads just where the wing starts to straighten out from the fuse it will stay on the cg machine but still was nose heavy. I then added the 1 ounce of weight like I previously told you which I don't like to do but it fixed the problem. Now that you found those weights I going to look at mine and see if there. Thanks for the info and let you know what I find. Good luck on yours and good flying!

Roy B.

[boomer108]

RE: c.g. balancing 1400mm corsair

Hello bagger
You balance it inverted with gear retracted. I have the Olathe version and the CG is on the mark with a 4000mAh 4S in the pocket with no additional weight required. It flies very nice with both the drop tanks and rockets on board with about 4% up elev trim on my DX8. Want to give you a heads up that that this thing will land hot n heavy unless you have full 30 degrees of flap. Using 15 degrees to take off is ok but if you use the same amount to land it will be hot, that is because the wing chord is not as wide as similar in this size birds like the Hellcat, Mustang, Warhawk or even the Trojan.

Hey War bird!

I just read your post and if you balance with the gear up on a Corsair,the gear rotates aft which would in effect move your cg aft. So with the gear down your cg moves forward which is why with your 4000 4s it balances on the mark with the gear up and could account for the need of 4 percent up elevator trim and  why it lands hot without 30 deg  of flaps. Just throwing my 2 cents in. Good flying War bird!

Roy B.

[OV10]

RE: c.g. balancing 1400mm corsair

Hello Boomer,
Not quite sure of the message your trying to point out in regards to my posting to bagger. Are you questioning the methodology about why the Corsair is balanced with gear up?? All warbirds that have rearward swinging gear(ie - F4U, P40, F6F and A1 for example) are balanced this way. The manufacturers of the real life full scale aircraft did this also in the design. The aircrafts primary flight configuration is with gear up for the majority of its air time and is in fact nose heavy when the gear is down. I use the larger 4000mAh batts on all my warbirds which is more than what FMS designed for on this F4U using the 3600. The 4 percent up trim on mine is because of the dirty airfoil that the drop tanks and missles effect on the airstream. I also do not adjust elevator trims for gear down because the flaps help negate that nose heavy aspect whereas on other birds some elevator down mixing with flaps is done to counter the nose ballooning upwards. With regard to landing hot, the last part of my initial post about the chord comparison was to give an understanding that it is hot when compared to those other airframes. I have and fly all of those that I sited in above example. On the Warhawk, Hellcat and Skyraider they don't need full flaps to help tame down the approach airspeeds because of the wider airfoil chord for lift than that of the Corsair. As the warbird demonstrator for our club at airshows and flight instructor I fully understand all the dynamics involved regarding CG interactions on flight control. So in conclusion to airframes with gear of this retract nature, nose heavy with gear down is much more manageable than a tail heavy bird when gear is retracted. What many disappointed novice pilots experience when they CG the airframe with the gear down is the tail heavy syndrome during flight which is well know to be avoided due to the pitchy control aspects or worse. Hope this helps give some guidance.
Best Regards,

[boomer108]

RE: c.g. balancing 1400mm corsair

Hey War bird,
I wasn't trying to dispute your methodology I balance my Corsair inverted with the gear up just so I won't be tail heavy in normal flight I just don't understand all the differences people seem to have in balancing the Corsair,I guess everybody has a different approach and preferences. As far as understanding center of gravity that was on of my duties as a In-flight Refueler on the KC135 for 23 years it just seems the Corsair is a strange bird to balance. Sorry for any misunderstanding War bird. Good flying!

 . Roy B.

[bagger]

RE: c.g. balancing 1400mm corsair

Roy B. and Warbird Charlie,

Got my new fuse and cowling today from Motion. Plan on transferring everything over this weekend and try to get this baby going.

I am not going to use the big honkin' weights that were in the front of my other Corsair. Going to see if I can get it balanced without them. They are at least 2 ozs. together so I figure that will make it not so nose heavy. I won't glue the cowling in place in case I have to use them. Will try everything else first.

Warbird, I am going to balance it your way with the retracts up. I have the FMS Mosquito and the gentleman who did a build review on rcinformer.com said to balance it with the retracts up because the weight shifts to the tail when gear is retracted. He said to balance that plane at 85 mm from the lead edge with gear up and it should balance with no more than 1 oz of weight in the tail. Mine balanced with 3/8 oz. And yes, the gear doors were a BEAR! So on the Corsair, only nose weight will be the battery and the gear will be up when balancing at 110mm and we'll see how it turns out.

Will keep you guys posted on the outcome. Thanks again for all your input. Much appreciated.

bagger

[bagger]

RE: c.g. balancing 1400mm corsair

Here's where I balanced my Corsair.  A little nose heavy.  Only thing in the nose are the battery and the EMC.  The 2 weights I found in the nose are in the compartment where the vertical stabilizer slips into the slot.  If I added 1/2 oz more, plane would be level.  I'll give it a shot and see how it flies.  Thanks for the help guys.

bagger

[boomer108]

RE: c.g. balancing 1400mm corsair

Hey Bagger!

That's how mine looks when it sits on the GP balancer everyone says warbirds should be slightly nose heavy so you should be good. Mine flies fine. And I did look for those weights behind the cowl,but I didn't find any. Mystery! Anyway good luck and good flying.

Roy B.

[ryramZ]

RE: c.g. balancing 1400mm corsair

Read the customer reviews and you'll see most feel the 110 cg is wrong. Also many on rcgroups feel the same way. 90-95 seems to be the mass consensus.

[bagger]

RE: c.g. balancing 1400mm corsair

Read the customer reviews and you'll see most feel the 110 cg is wrong. Also many on rcgroups feel the same way. 90-95 seems to be the mass consensus.

Hi Ryan,

I have read the reviews. In fact, 2 of them are mine. I couldn't get a proper c.g. so I built a tray after I was told to try and mount the battery in the space under the canopy. Was able to achieve the c.g. by both methods but the tray worked better. On this plane I wanted to use the battery compartment provided. As I stated, I found 2 large weights in the nose. You can't see them with the cowling on. Removed them and placed them in the tail and the picture tells the story. We'll see how this set up works. (110mm) I like this plane so my hanger won't be without one. Thanks for your input.

bagger

[OV10]

RE: c.g. balancing 1400mm corsair

Hello bagger,
Very interesting about finding weights inside the cowl and removing/relocating to the tail. The bird appears in your pic of post #16 to be in proper balance config with the CG set(as you said) at the 110 factory recommendation. That weight relocation I have to believe is gonna have to help keep it from being nose tipsy during taxi. Please give a follow up on how it flies with this configuration. As I had mentioned back in my post #4 to ya, my CG was at the RCgroups recommended 95. You have sparked my interest as to whether or not the real CG is 110 and these hidden weights has been some trickery. If your flight proves positive I will tear the cowl off mine to find those weights and relocate them as you did in order to make it better on ground handling. Can't wait to hear how it goes!!!
Best Regards,