mark IX

My Feedback: (9)

What motor were you using? Imagine sitting in the cockpit of a P-51 and during a high speed turn, you see the alum skin start to buckle............ This is why I stick to models...... my feet are on the ground!!

sjhanc

My Feedback: (3)

To answer your question, I am currently using a RimFire 50cc brushless motor at about 28.5 lbs. gross wt.
During WWll most fighter aircraft were built to withstand 7Gs because that was the max A pilot could stand without G suits which came very late in the war. The only plane able to take higher G forces was the Bearcat which was fitted with disposable wingtips that automatically blew off when overloaded. If you look at high res photo graphs of Unlimited Racers you will always see distorted sheet metal on the fuse and wings. The question is always "How much can it take?". When I flew in my Huey helicopter during Vietnam the tail-boom was always distorted as soon as the pilot pulled pitch for takeoff and stayed that way until landing. The sheet metal on aircraft is so thin it rivals beer cans, the underlying structure keeps the shape aerodynamic for minimum drag. If you don't like the idea of distorted metal don't look at the wing of the airliner you are riding in.
When I recently flew in the Collings Foundation's P 51 B "BettyJane" I looked for distortion but didn't see any, maybe because it was lightly loaded (only enough fuel for the particular flight I was on) and all the maneuvers we performed were low G".
5/30/15 update- I have had time to pull all the hatches on the bottom of the wing to inspect for separated glue joints and cracked ribs and sheeting. I am happy to report that the distortion visible in this picture is most likely the covering being pulled away from the wing sheeting, I can fix this by ironing the film down on to the sheeting. A near 90 degree bank like this can generate as much as 9 g's so the weight of the airframe (28.5 Lbs. x 9)= as much as 256 lbs. It proves that the TF design with the reinforced wing and fuse is pretty tough. I did not intend to stress it this hard, what started as a wide radius turn was tightened up by flying into a strong gust of wind rolling off the nearby treeline. The turn started low below the treeline and as it turned and climbed higher the wind struck it in the belly. I noticed the turn tighten up and let off on the elevator but it was already into the gust by then. The runway conditions were almost dead calm at the time so it could have been strong thermal activity.

sjhanc

My Feedback: (3)

This is a high res. photo of the turn. It takes a while to load it but I was afraid if I downsized it the detail would not show up. The web page automatically reduces the size but you can click the photo to see the max resolution.

rossmick

All

I remember somewhere in the thread a discussion on not using the supplied spinner. As we had our clubs static display at the Pima Air Museum this last weekend I had an opportunity to talk to several guys who had flown the TF P-51 and one of the horror stories was the failing spinner and tearing the engine out of the front of the plane. He said do not use the supplied spinner, and to find a non alum. one as he also had a failure with the True Turn spinner. He recommended carbon fiber as they are much lighter and need little or no balancing. I am looking for thoughts and information on where to get a true scale spinner as I recall the supplied one is not scale. I have a carbon fiber spinner on my Giant Stik and it works well, but I don't know of any scale carbon fiber ones for the P-51. I am finally over the flu bug and feeling human again, so back to work to get this bird in the air.

chris923

My Feedback: (53)

Ross,

I have used, Dave Brown, True Turn and the spinner that came with the arf. I have never had a spinner failure. 100's of flights, 4 TF-P51's. I have not even heard of anyone I have been around having this problem.
Poor installation, lack of maintenance, poorly balanced props, poor engine install? IMHO a carbon fiber spinner is a wait of money and less durable.

sjhanc

My Feedback: (3)

rossmick,
I have had 5 of the TF spinners, I still have 2 of them that I don't use. One of them developed a crack at the prop opening, I replaced it with a TRU-TURN which I still use after hundreds of flights. Another fell off at the Sanford FL, club warbird meet-no damage to the plane and no apparent reason for the failure, It was the earlier 6 bolt version. I also get good service with the Dave Brown versions ( half the price of a True-Turn). If you have the 8 bolt TF spinner I would use it but balance it and look for wobbling at low idle. If it runs true its probably OK. I haven't been able to find a carbon P 51 spinner. I like to polish my aluminum spinners, I think they add a lot to the looks of the plane. A few minutes work with some never-dull brings out the shine and it work-hardens the aluminum surface. The other TF spinner I still have has .008 in. axial run out and is unsafe and can't be balanced. The Dave Brown and TRU-TURN spinners usually don't need balancing, if you have both of them don't get the back-plates mixed up, it could cause problems.
I wouldn't worry about the scale appearance of the front end on an ARF, almost nothing on the front of any brand is true-scale and the public doesn't notice the differences. If you can find a Tony Howard scale exhaust kit it is a definite detail upgrade (He passed away and there are no plans to market his product).
If you are building a scale Mustang you have to manufacture everything yourself to get it scale. None of the P 51 kits or ARF products that I have seen go to much trouble to get the scale detail right. They still look like Mustangs though and are my favorite plane.
I am assembling the Hanger 9 60cc version and while it has a lot of scale parts in the box, little of it is true scale except for the scale out lines of the airframe. It still looks nice though.
If you compare The tips of the TF plane tail surfaces to the real P 51 you will notice that the model has an incorrect shape, the model has rounded top views while the real plane is almost straight line with sharp radius corners both vertical and horizontal.
I had never noticed this until it was pointed out by a Mustang veteran pilot. This is easy to correct and I have fixed it on all my planes. Fortunately the H-9 plane is closer to scale so doesn't need fixing.

rslstft

My Feedback: (10)

Ross,
I agree with sj and chris. Some of the early TF spinners developed cracks at the prop opening or screw holes, but the biggest problem was with balance. If the person you talked to had a problem with a Tru-Turn, he did something wrong, plain and simple. Those are perfectly balanced and I have 100s of flights on several of them. You CAN overtighten the bolt holding the cone on and maybe that was the issue, or even a prop out of balance can cause spinner problems.

rossmick

All

Thanks for the info. Sounds like Tru-Turn is the way to go. Also trying to scale the bird does seem counterproductive so I will pass on that idea. One thing I have found with this great sport is that every individual has an experience and an opinion, so multiple inputs on a subject always produces the best solution or concept. Again, thanks for taking the time to respond.

SWORDSN

My Feedback: (13)

My original spinner had 4 screws attaching the cone to the back plate.This one developed a crack and TF sent a replacement which has 8 screws.The replacement has over 400 flights with no failures. Just my experience.

oldtimer4759

hi all, this is a great model to fly, once the retract mounts are fixed, I have the DLE 55ra in mine, thinking of putting a decent prop on it, a 2 blade Mejzlik, been told a 22 x 10, is the one to use, what have you found with the same engine set up.
thanks Oldtimer

Ralph White

Oldtimer, I have been flying the TF P-51 for a year now. Have about 85 flights on it. Changed mine to a P-51C model. I am using a Mejzlik 21 x 10 on mine with the DLE 55ra. I started with a Zoar 22 x 10, the changed to a Zoar 21 x 10, and then the Mejzlik 21 x 10. The 21 x 10 flies my P-51 better than the 22 x 10 props I tried. A little faster and seems a little more on a rail with the Mejzlik 21 x 10. I have not tried a Mejzlik 22 x 10, have no reason to as the 21 x 10 flies the way I perfer.
Ralph

Here is a video on mine. https://www.youtube.com/watch?v=CUwA9aJlifQ

oldtimer4759

G´day Ralf, many thanks, just the info I was after, a 21 x 10 it is, loved the video, very nice field and great flying.
thanks, Oldtimer.

chris923

My Feedback: (53)

Mustang Flyers,

I just posted for sale on RCU a set of Sierra TF P51 main gear if you have any interest.

Ralph White

Oldtimer4759, Pleased I could help. Thanks for the nice comments on the video.
Ralph

ForcesR

Ralph and Old timer; did you both use the soft isolation mount to mount your DLE 55-RA onto? If you did, what did you do to resolve the issue of the two bottom 55-RA standoff flanges that cover approximately 1/4 of the soft mount rubber bushing holes?

Roger

Ralph White

Roger,
No, I did not use the soft isolation mount with my DLE 55RA on my TF P-51. I used the standoffs that came with the DLE 55RA. I used 1/4" aircraft ply to get the correct distance for the engine to line up with the nose ring of the fuselage. It takes four 1/4" layers of ply. I also reinforced the bulkhead to the fuselage sides, top, and bottom on the inside with 6 oz fiberglass cloth. Here's a picture. (The mount is not angled, it just looks like in the picture.)

Ralph White

Roger, Please notice I edited the above post to four 1/4" layers of ply.
Ralph

ForcesR

Ralph, thank-you very much for your reply and the addition of the photo. I just wonder why DLE changed the mounting foot print on the RA instead of leaving the foot print the same as the regular DLE 55? Oh well, just a little more work than what I was expecting in mounting the RA. Also your P-51C is a really nice looking Mustang with that color scheme, I enjoyed watching the video too,

Your reply is very much appreciated!!

Roger

oldtimer4759

G´day Roger,
I bought mine already built, not sure if it is a soft mount, I will get it down and take some photos of it, they might help.
Oldtimer.

grbaker

My Feedback: (29)

Ralph, just curious to know if this was the WWII prop?

rossmick

It's late so short and sweet, Maiden flight (finally) and it took 3 clicks nose down, none on rudder or ailerons. Stable flight and with half throttle on the DA60 flew what observers said was very scale speed and rolls. I elected to not use flaps and left the gear down for the flight just to see how the bird handled. The landing speed was high as I was afraid to pull off much power on final. The gear are as stiff as a board, I hope the springs soften some with use. It is obvious that one needs flaps to get the approach speed down where it belongs. The only problem I had was with the Sierra gear as the mains keep rotating on the axel, both gear rotated about 30 degrees inward after the final landing when it went off the end of the runway. The prop never touched the ground so I just shut it down and went and got it. Since, I have replaced the set screw with a Allen head bolt so I can get some real toque on it. Next week will find out if that solved the problem. I know on the taxi run several weeks ago the left main rotated and that time it got the prop. I also upped the pressure on the system to 120#s with a recommendation from a fellow flyer, seems to work well as gear always goes in to lock position.

sjhanc

My Feedback: (3)

Rossmick,
I read in a post some where that there is a rollpin that needs to be installed after the wheel alignment is done to prevent the turning you got. There is a predrilled hole to locate the pin but you have to finish drilling the hole after you set the toe-then drive the pin in. I can't remember which brand they referred to but it was for the axle turning problem.
I am in the middle of installing the ROBART air retracts I bought for my new H-9 60cc Mustang. This is not a simple drop-in, I have had to do a lot of grinding on the mounts in the wing and even grind a bevel on part of the edge of the frame to get them into the wing. Then there is building the links that connect the gear doors to the struts. The parts for the links were not included in the package so I went through my stock of control parts and found some to do the job. The specified length of the links in the instructions is wrong for the ROBARTs so I had to do a cut and fit. I finally got the left strut door finished and started on the right side. I could not get the RH side wheel to go up into the wing after hours of shimming. To make the story short I found a mistake had been made welding the strut socket on to the weldment trunion at the wrong angle. to verify the problem I took a trunion out of a plane under construction and got it to work. I saved a lot of money with the ROBART gear but had to do hours of extra work. Its a good thing my time is free.
The next time you fly it spend some time in slow flying and trim it for level flight with the gear and flaps down making low passes to discover the needed amount of throttle- This will build your confidence for the landing approach. When making slow turns it will be sluggish at times, just add a little throttle and more rudder. When turning downwind add more power to maintain altitude. This will overcome the inertia effect.
Congrats on a successful maiden flight.

CRJDriver

My Feedback: (57)

Ross,as sjhanc stated, the roll pin does need to be installed in each gear. The set screw is only intended to hold the gear in the proper orientation prior to drilling the hole through the strut. Congrats on the maiden. Flaps are a must on this airplane. Carry a little power on final down to the flare and it will land like a butterfly with sore feet.

Ralph White

grbaker,

No, I did not use the WWII Zoar prop. The Zoar props I have are the PJA Series Beechwood Props. The Zoar 22 x 10 flew the P-51 okay. The Zoar 21 x 10 flew it better, faster and on a rail. The Mejzlik 21 X 10 flew it the best. I may try the 22 x 10 props again after the DLE 55RA gets a lot more running time on it, but I don't expect the 22 x 10 will be as good as the Mejzlik 21 x 10. The video in my post # 3611 was with the Mejzlik 21 x 10.

Ralph

oldtimer4759

G´day Roger,
I didnt build mine, but here is a picture of the way it has been done, hope it helps.
Oldtimer.