Top Flite 1/7th Scale P-51 ARF Build Log - Page 11 - RC Groups
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Apr 12, 2009, 11:03 AM
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Coastwatcher's Avatar
man that is a shame . First thought it was a stall also, question is why. Was a bit shakey lift off /climb-out. It totally disappears for maybe 1 sec on my video screen, that was enought time for me to LOOSE direction/ and attitude. Maybe it was also enought time for this to happen to him in person. It seemed WAY FAR out for maiden comfort . Being disorineted, Possiby chopped the throttle, stalled , and was next theing he knew it was headed straight down and BANG! I guess the 2.4 could have dropped signal, if the rX lost voltage, lose connection, low batt cut off, what ever or the signal was blocked by poor RX placement, it still takes a bit of experience to recover a bird in this fix. Hope he used a AR7000 and not a 6000 in this plane. I place my RX and its satelittes back far in the fuse . I like a 14-24 inch gap away from from the batterries. Batts, speakers, motor, GAS ENGINE , ect will block a signal. Hope he will figure it out and continue his efforts.

On a more positive note.
I have a friend who "JUST" this past week maidened his TF -60 MUSTANG and it preformed BEAUTIFULLY ......with a EFLITE 90 in her .
Congratualtions JIMMY!!!
Last edited by Coastwatcher; Apr 13, 2009 at 01:52 PM.
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Apr 12, 2009, 12:52 PM
Fly 'em fast!
RCMustang's Avatar
I see two mistakes here: 1) He did not get enough forward airspeed going. The P-51 is notorious for wanting to torque roll on takeoff. I've done it with the TF. 2) It may have been tail heavy and wanted that down elevator. When they pitch up like that, the result is a stall and a spin. Ask me how I know about that mistake too...

Too bad for the loss. It was a beauty.
Apr 12, 2009, 08:22 PM
corsair nut's Avatar
looked like tail heavy to me.
Apr 12, 2009, 08:59 PM
Registered User
CorsairJock's Avatar
Originally Posted by corsair nut
looked like tail heavy to me.
A popular misconception is that an aircraft that is tail heavy will continue to climb, regarless of pilot input.

What actually happens is that the aircraft becomes extremely pitch sensitive, to the point that any elevator input over-corrects, and the aircraft begins to "porpose": begins repeated cycles where it alternates between pitching up and pitching down, and each cycle becomes more extreme.
Apr 13, 2009, 02:06 AM
drksyd's Avatar
I may be off here but from the beginning the prop looks a little small. It got enough airspeed to take off but after that sudden pitch up it didn't have enough thrust or speed and caused a stall. Again, this is hard to call since we can't see how it got into the death spin.

I agree with you on the porpoising but this is how I killed my VQ A-26. The plane was way too tail heavy but I had it set a little more forward than what the instructions stated. It climbed pretty steeply so I backed off the throttle, did that a bit too much and stalled it. Inexperience with a plane being so off balance and higher wingloading, I learned the hard way.
Jun 24, 2009, 06:10 PM
Former Durafly Brand Manager
Stuart Warne's Avatar
Yeap I'd certainly agree with you guy's. He seems to want to pull it up into the air far too soon and then seemed to loose all speed and control authority result in the stall/spin in. I never understand way some people as so keen to get there models up into the air in an instant. A plane looks so good on a long T/O run, plus its fun to do right.

Guy's I'm thinking about considering the new TF P47 .60 ARF. Just wondering if anybody has A123 experience on the TF P51? I believe that most of you guy's are running off 6 cell packs, so I assume a 7 cell A123 pack would be the way to go?

Jun 24, 2009, 10:11 PM
Nothing like a good WOODIE!
cooper998's Avatar
I just maiden'd mine today with some not so good results. Fortunately the plane survived, now the bad stuff;
Fullthrottle caused a viscous vibration from the spinner so I took it off to verify that was the problem and the vibration went away (prop was balanced) so I proceeded to taxi test the plane and all looked good so I took off and she immediately climbed like crazy and the elevator was extremely sensitive indicating a tail heavy condition. After putting in all the down trim I could I started to set up for a landing and I would have greased it but she dipped a wing and the left gear caught popping the trunnion out of the retract and loosening the front mounting rail.
The fix is easy for the wing and retracts, I have a set of Springairs I am going to put in after I re-glue the mounting rail. The spinner on the other hand is going to be a problem trying to balance, has anyone else experienced an unbalanced spinner?

My setup;
Scorpion 4035-16
Castle 80
6s 5000mah
16-12 APCe
Hatch cut for battery access

Jun 25, 2009, 05:44 AM
Registered User
CorsairJock's Avatar
cooper998: so much info, yet so little. For example:
You state that it was tail heavy, but you failed to state where the C.G. was set.
You state that the elevators were overly sensitive, but fail to state what your throws were set at.
For that matter, we know little if anything else about your's (what is power set-up/ how many watts, how much did it weigh.

It HAS been noted (documented in this and other threads) that many, if not most of us are finding the need for some elevator down trim.

I have used 2 spinners on mine (1 is 'normal', 1 is modified/ set-up for 4 blade prop): neither have shown indications of imbalance. I HAVE experienced a bent (Great Planes aluminum) prop shaft adapter.

stuart warne: I for one know little if anything about "A123" cells. If you are using them, you probably know more about them than most of us. Perhaps you could educate us a little about them (what are advantages/ dis-advantages over LiPo?).
Jun 25, 2009, 08:36 AM
Nothing like a good WOODIE!
cooper998's Avatar

OOPS yeah I think I left out a bit of info, The CG was set to the manuals specs which are 5 5/8" back from the leading edge. The problem arose when I removed the spinner but failed to rebalance the plane. Elevator throw was set again by the manual 5/8" high rate and 3/8" low rate (I switched to low rate right after takeoff).
On my power setup she drew 50 amps at right about 1060 watts, unfortunately I did not weigh it yet.

Last night I dug out some old Spring air retracts I am going to use. I drilled and reamed out the hole to 5mm to fit the stock wires and I will be epoxying the mount that came loose this morning. Later today I am going to check my prop adapter for runout and then check the balance on the spinner itself, hopefully its ok. I did find that the Great Planes Electric motor mount mount flexes a bit too much so I will add a brace to the middle of it to fix that problem.

Need to get her done today since our club is having a warbird fly-in this saturday.

Jun 25, 2009, 03:39 PM
Registered User
CorsairJock's Avatar
It wouldn't hurt to move the C.G. forward about 1/8 to 1/4". Remember: the manual is suggesting to balance it without fuel. Adding fuel would move the C.G. forward some, and since your's is electric powered: there is no fuel to add.
Also, the control trhows: the low rates are the way to go on this bird (3/8" up/ down), but with some neg expo (I like at least -32).
Last edited by CorsairJock; Jun 25, 2009 at 06:00 PM.
Jun 25, 2009, 05:48 PM
Nothing like a good WOODIE!
cooper998's Avatar
Thanks for those suggestions, I am moving the cg forward to 5 1/2" as well as reducing the elevator throw. I almost have her back together, the retracts are almost done just need to finish the plumbing. I ran the motor with just the spinner and had the same vibration so I tried a trick from the edf's, I slowly rotated the cone in relation to the back plate and found a sweet spot where there is little if any vibration noticed and marked them both so they would go back in the same spots.
I machined two supports for the center of the GP motor mount and there is no flex noticed.

I was hoping to fly her again tomorrow but the weather may not cooperate, so the next flight will be at our warbird meet Saturday morning.

Jun 27, 2009, 11:24 PM
Nothing like a good WOODIE!
cooper998's Avatar
Well at least about 95%. The Springair retracts were working fine, found the sweet spot for the spinner but unfortunately on my first attempt she nosed over (wet grass) and she started vibrating again. After that I decided to take the spinner of, re-balance the plane and go for it. Had three successful flights save for landings which I successfully nosed over every time.

I have a Tru-Turn e-prop adapter on order to see if that cures the vibration, if not I'll contact Top Flite about replacing the spinner.

Jul 11, 2009, 12:45 PM
Registered User
CorsairJock's Avatar
I'll have mine flying again at the Mid America Electric Fly-In on Sunday, July 12, 2009.
Hope to see another one there this time, so we can do a formation fly-by.

In case you dont know about the Mid America Electric Fly-In, here is a link with info that I started recently:
Jul 11, 2009, 10:17 PM
...missing the PE Slope Rebels
Flying Beagle's Avatar

will see you there, look for my lozenge covered Staaken bomber and Fokker DVII

Jul 14, 2009, 04:45 PM
Registered User
CorsairJock's Avatar
Pics taken of mine on Sun, July 12, 2009 at Mid America Electric Fly:

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