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-   -   Airfield P51 Mustang CG Help (http://www.Wattflyer.com/forums/showthread.php?t=74319)

Karnsy 08-18-2014 01:20 AM

Airfield P51 Mustang CG Help
 
Hoping someone out there has this 1100mm plane and can tell me if they had any cg issues and if so what they have done to solve them. I have one and went by the cg as per manufacture but still flies awful. I put it on a cg stand and made it just slightly nose heavy with battery all the way forward & secure and by adding 3/4 of an oz. to the nose but just will not fly well. Flies ok sometimes for a while then coming into corner nose goes up and its like I have no control over thing. Almost ready to cut my losses. Anyone?

suresharp 08-18-2014 06:48 AM

The plane is balanced thats good. Now you must increase power issue. check timming for cell count (esc), check throtle rang setting of transmitter, battery size and c rating. Check motor spec for prop size recomended

CHELLIE 08-18-2014 07:37 AM

Quote:

Originally Posted by Karnsy (Post 955410)
Hoping someone out there has this 1100mm plane and can tell me if they had any cg issues and if so what they have done to solve them. I have one and went by the cg as per manufacture but still flies awful. I put it on a cg stand and made it just slightly nose heavy with battery all the way forward & secure and by adding 3/4 of an oz. to the nose but just will not fly well. Flies ok sometimes for a while then coming into corner nose goes up and its like I have no control over thing. Almost ready to cut my losses. Anyone?

Use 4s 2650's Lipo and a 2 blade APC 11x7 , 12x6 as well as APC 12x8 , check your watts and amps with a wattmeter, that plane has a low 750 KV motor, so it will handle a 4 cell with no problem, a 2 blade prop will work better than the 4 blade prop, give the motor about 1 to 2 degrees of down thrust, the down thrust will load the wing and make it a solid flier, check the wing and stabilizer incidence, make sure that they are at 0 - 0 degrees, make sure the original ESC will handle a 4 cell lipo and use a seperate 5 amp UBEC, if not use a 40 amp ESC with a Switching BEC, check the battery hold down velcro, it comes loose at times, epoxy it in place, Hope that helps, Chellie

CHELLIE 08-18-2014 07:52 AM

here is a 40 amp switching BEC ESC, HK has not updated the info from linear to switching on their ads,

http://www.hobbyking.com/hobbyking/s...ontroller.html

http://www.hobbyking.com/hobbyking/s...est-avatar.jpg rc007 http://www.hobbyking.com/hobbyking/s...s/thumb_up.png 10 points - 8/12/2014

BEC of the 40A Plush ESC is linear or switching? Description on HK website says it is linear and on user manual says it is switching.
http://www.hobbyking.com/hobbyking/s...est-avatar.jpg Johan http://www.hobbyking.com/hobbyking/s...s/thumb_up.png 8 points
I have four of these ECS and it is an switching BEC.
BEST ANSWER CREDIT AWARDED

CHELLIE 08-18-2014 08:09 AM

if you continue to use the stock ESC and 3 cell lipo, use a seperate UBEC of 3 amps or bigger, the bec has been known to fail on those stock ESC.

http://www.wattflyer.com/forums/show...highlight=ubec

fhhuber 08-18-2014 09:35 AM

Sounding like an accelerated stall...

P-51 an many other fighters can have a nasty snap tendency if you apply excess elevator, especially if the ailerons are both trimmed down slightly.

Often a turn or two on the clevises pushing both ailerons up (might not even be able to really see the difference) will help by effectively adding a bit of wash-out (or eliminating undesirable wash-in)

JetPlaneFlyer 08-18-2014 12:13 PM

Hard to say what the problem is withoutseeing it in action but if it flies ok most of the time it's probably not CG related, plus if it balances as per manual it should be ok. As hinted at above, maybe too low an airspeed and/or pulling the turn too tight?

I take it that the model hasnt been modified and isnt overweight?

CHELLIE 08-18-2014 06:38 PM

Quote:

Originally Posted by Karnsy (Post 955410)
Hoping someone out there has this 1100mm plane and can tell me if they had any cg issues and if so what they have done to solve them. I have one and went by the cg as per manufacture but still flies awful. I put it on a cg stand and made it just slightly nose heavy with battery all the way forward & secure and by adding 3/4 of an oz. to the nose but just will not fly well. Flies ok sometimes for a while then coming into corner nose goes up and its like I have no control over thing. Almost ready to cut my losses. Anyone?


On all of the reviews on this plane, everyone is saying that the CG is wrong on the manual, and they have to add weight to the nose, also lots of reports that this plane is underpowered, some people are going to a 1050kv motor with a 3 cell lipo, rather than using the 750kv motor, others are going to a 4 cell lipo for more power with the 750kv stock motor, Go to RCG for more info on this plane.

Karnsy 08-25-2014 06:08 PM

Well I can understand all of that. Turns out for me I tried flying it by adding 3/4 of an ounce to the nose so it was slightly nose heavy. Did not make out well. So I made it more nose heavy by adding a hole ounce more weight and now it flies great. I can trust it now and am thinking the cg must be off. Because of that weight it comes in a little strong but I will get used to that. I can see how some feel it is under powered, as I can go along with that but for now I'm good. Heck just got the thing to fly right.


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