Official FMS 1400mm P-51D V8 Thread

[Shirty]

Is this the stock prop? Have you done anything to prevent it from blowing apart? I have seen many of them just fly apart with too much power...
Also I have seen this 4s set up in person with the zip tie mod. It was more than enough for me since I am not trying to break any speed records. I want it to have thrust for climbs and scale passes. Here is my buddy flying his equipped with this motor and zip tie pitch mod...

Hey mate.

Yes, it's the stock prop. Ive done nothing to stop it blowing apart. There was only 4 guys who reported on the rcg thread their prop couldn't handle the extra rpms, though whether they had a unbalanced prop, or had a previous ground strike etc and whether that contributed to the prop exploding, no one knows for sure.

I've done this conversion on the fw 190, my Dallas darling and both peties. Just on the three Mustangs, I've got well over 500 flights on this set up, as I did this conversion 3 years ago. Watt tests by myself and a couple of others early on, showed the 4258 on 4s, actually puts out less power than the stock 540kv, or the 580kv. (No zip tie mod),but less amp draw obviously. Hence me saying it's not really worth it on 4s, as it's less power AND more weight. (Though the prop mod might make up a bit of this lack of watts, I don't know, I never tested the prop mod).

Your mates seems to get along nicely though. Nice landing too. :)

[gooniac33]

If you are talking the 4258-550kv, it's from the fms Olympus. Myself, licobra and xviper were the first to do it several years ago, and it's basically a drop in fit. Note if you're going to run 4s, you're better off with the 650kv. The 550kv is designed for 5s and 6s.

Is this the stock prop? Have you done anything to prevent it from blowing apart? I have seen many of them just fly apart with too much power...
Also I have seen this 4s set up in person with the zip tie mod. It was more than enough for me since I am not trying to break any speed records. I want it to have thrust for climbs and scale passes. Here is my buddy flying his equipped with this motor and zip tie pitch mod...

[Shirty]

After talking to my buddy about the mods he made to his plane I will be doing the following. There used to be a larger 550kv motor in the larger birds. The larger diameter will not only help with torque but the rpms will be slightly higher since it is easier for it to spin. He did this mod with his Snoots Sniper and it is a rocket ship. The draw is low too which I like!. Bigger motor also means slightly more nose heavy which I prefer as well. I will add the zip tie mod if needed after this but I think it will work just fine.... Let me find the video...

If you are talking the 4258-550kv, it's from the fms Olympus. Myself, licobra and xviper were the first to do it several years ago, and it's basically a drop in fit. Note if you're going to run 4s, you're better off with the 650kv. The 550kv is designed for 5s and 6s.

[e4dragongunner]

Have the 650 in mine as well. Started there. No Clue what the 540 was like. All I can say is she flies superbly on the 650, also has sound card, aluminum gear plates. and 85 amp Mantis ESC. ZERO clicks of Elevator trim on maiden.

[gooniac33]

After talking to my buddy about the mods he made to his plane I will be doing the following. There used to be a larger 550kv motor in the larger birds. The larger diameter will not only help with torque but the rpms will be slightly higher since it is easier for it to spin. He did this mod with his Snoots Sniper and it is a rocket ship. The draw is low too which I like!. Bigger motor also means slightly more nose heavy which I prefer as well. I will add the zip tie mod if needed after this but I think it will work just fine.... Let me find the video...

[wrongroad]

G'day Grossman56,
I mentioned that fact as by my bush math, the improvement was about 12% from the 540 to the 580 and then only about the same from the 560 to the 650. However, if you go from the 540 to the 650 you are looking at a 25% increase and that is noticeable.
It also helps to fit fresh [read new] batteries when you are doing tests like this.
If you are using batteries that have a bit of age on them, the loss of performance in the batteries could mask any increase in motor performance.
I know that my batteries have lost at least 15 to 20% off their best performance from new. They are at the end of their life span so it would be a waste of time trying to compare motors with old and new batteries if that makes sense to you and the rest.
I am absolutely 100% happy with the performance of the 650 motor on 4s batts.
Is it a rocket ship?
No, but the performance with this set up is more than satisfactory.
What I like about the Mustang is that there is room to improve and modify the model to suit the individual pilot. I like the fact that we can change things to make the models our own and stand out from the pack.
I have put balsa over the turtle deck and made new battery boxes on each of my P-51's. The prevents the dreaded gatoring of the foam.
I have nearly six hundred flights between my three Mustangs and, with some minor parts changes [and a wing set change due to my own fault while not flying, read a car door] these model have been very reliable and flyable in nearly all conditions.
I fitted bronze wheel bearings to stop the e clip from wearing through the wheels.
I just need a lot more runway to stop as the friction rate is so low.
Regards and respect
Daryl

[Grossman56]

Had Shangrila with the 650kv in her, up last evening. It's a bit better than the 580kv, but nothing to write home about. One of the guys mentioned a whole back, that if you go from the stock 540 to the 580 and then to the 650 as I have done, it doesn't seem like all that much of an improvement. But if you go directly from the 540 to the 650, it looks like a big improvement.
I'd agree with that, and she flies great with the 650.
I also changed out the connectors to ball links on both my FMS P-51s, just for added peace of mind.

Grossman56

[wrongroad]

G'day AZ,
I know I am a bit late with this but check the security of the rudder push rod at the servo end.
I had my BBD go ape one day with the model yawing badly and then wagging the tail like a dog looking for a cookie!
I called that I had control issues and set up to land. All of a sudden, she started to behave herself and the landing was a cracker.
So, yes, I was dumb enough to go up again because the problem had 'gone away'. Yeah, riiiiiiggggghhhhhht!!
On the first circuit she was all over the place like a palm tree in a cyclone. However, as I set for landing, the problem went away.
This time I was not stupid enough to go up without finding and correcting the problem. I quickly discovered that the grub screw in servo arm was not done up tight enough. Out with the Allen key set, find the right size and do the rotten thing up. A bit of contact glue over the top and there has never been an issue with the screws backing out since.
Now, why the problem went away while landing and taking off, I have never been able to work out.
It is also worth your time to check the integrity of the two screws holding the vertical stabiliser on. These can and do work there way loose over a period of time and this, in turn, allows the fin to flutter.
Earlier models, the V7 comes to mind, only had a foam tongue to secure the vert stab to the fuselage [along with the screws] while later versions have a hard point and is much, much better.
I have three P-51's [four if you count the first BBD that was cut in half by another model while waiting for her maiden flight] and the tail does need attention from time to time. Do not forget to do your checks and that goes for everyone.:)
I have not been doing all that much flying in the last few months but it is all looking good from here in.
I hope you have already found the problem but if not, at least you have another thing to check!
Regards and respect
Daryl

[Grossman56]

She's going to look sharp Gooniac! Wiped out My Little Gal II today, kind of figured it was going to happen, but she had a 650kv with the 85A ESC in her so now it's in Shangrila, that should make for a pretty great plane, not that she wasn't before!
I was running a 4250 580 kv in her before so it's not a huge upgrade, but since the motor was available, might just as well use it. Only drag is the ESC doesn't have very long motor leads and I didn't have a spare set, so I have to run the battery with the plug facing forward until I score a set of extensions.
Other than that, she should be great. It might just be my old guy eyes or wishful thinking, but the B model always seemed faster than the D model, so this should rock!!

Grossman56

[gooniac33]

It's a great plane Gooniac,have had mine for years and they fly beautifully,but a little different than my D model. They're slightly lighter although the difference is minimal, so it could be the airflow just as it was with the full scale ones. You guys already know that they're underpowered as well and about the metal retract sides so I won't get into that. Alot of my 'concerns' went away when I upgraded the motors to 580's. Had some spares sitting around from the Freewing P-51's after I upgraded them to 650's, works like a charm! We're sitting here at 5000 feet so the zip tie prop mod helps as well, and flaps at 15 and 30 degrees rocks with these planes!!
Again, I know you guys know all this, but in case someone new is reading, never hurts to mention it again.

Grossman56

I will fly this stock to begin with and then maybe add the new 650kv motor a little later on. My buddy has done that with his and it made a big difference!

Here are my 2 possible red tail schemes

[Grossman56]

It's a great plane Gooniac,have had mine for years and they fly beautifully,but a little different than my D model. They're slightly lighter although the difference is minimal, so it could be the airflow just as it was with the full scale ones. You guys already know that they're underpowered as well and about the metal retract sides so I won't get into that. Alot of my 'concerns' went away when I upgraded the motors to 580's. Had some spares sitting around from the Freewing P-51's after I upgraded them to 650's, works like a charm! We're sitting here at 5000 feet so the zip tie prop mod helps as well, and flaps at 15 and 30 degrees rocks with these planes!!
Again, I know you guys know all this, but in case someone new is reading, never hurts to mention it again.

Grossman56

[Shirty]

Nice, don't forget to post pics. :)

[gooniac33]

I have had lots of Mustangs... but never a B model... Just ordered the Snoots Sniper version and will be making it into a Red Tail... Can not wait!!!

[AkumaZeto]

My wings do stick out from the fuse like that on both sides and I have never been able to correct the issue. I did just glue my stab down as it was loose as well.

[Shirty]

Ok, did some work on my new one today and just thought about a couple of things when I was doing it that might help you as well mate.

First, check the elevator/horizontal stab for any side to side movement. One thing that all my mates and my mustangs show is they have a bit of side to side movement here. As part of my build on these I glue this stab in along the joins to reduce any flex or just loose fitting movement. All my mates with these have done this as well. It varies model to model, this one wasnt too bad but my mate Alan's redtail was terrible until we glued it. If it flexes or moves side to side, it'll make your tail wobble all over the place (esp at speed), and maybe this will help.

Second, check your wings are aligned. As I've noted before, it's my experience that these mustangs are still a great plane to own and fly, but there's a lot more qc issues slipping through of late with FMS I've noticed on all the different threads and forums - and my new one is a good example. You can see my wings don't fit properly, one side hangs out a bit more than the other, and doesn't run evenly with the fuse for its width either. The other side isn't too bad, but still not a nice aerodynamic fit. Wind passing over these will create a lot of little vortices, and I might get a little yaw like feel from it again, more so in the high speed stuff. (Especially since this will be a 5s/6s setup). Anyway, worth looking at yours mate hope it helps.

Other little qc things Ive noted about my new one before in this thread: wing screws wouldn't fit, end of the tail isn't painted, I've got a big dent in the fuse and they put the sticker over it anyway, missing a prop nut etc. All little things that aren't deal breakers, but a little frustrating all the same. Did a bit of final painting and detailing today, silver stacks (a must for a blue nose imho), and silver radio mast, painted the servo horn plate thingys black and silver to match the wing and elevator so they don't stick out like dogs balls, and a coat of minwax gloss for a nice finish and to help protect the foam from transport and finger marks in the foam etc when I carry it. Shiny! Lol. :)

[Shirty]

I have noticed with both my D and B she gets a bit of a tail slide in knife edge or just over the top of a loop, but that's about it - certainly not fishtailing everywhere like you describe. I just control it with rudder. (I'm so used to it now I just automatically add a little left rudder out of the top of a loop). As rifleman said, try moving it forward a bit further and see how you go.

One thing i will mention though, is setting your cg on the ground with a balancer is no guarantee it's correct for flying. Of course, it will be very close if balanced this way, but flight testing your cg is your best bet to get a plane dialled in. A lot of things can differ in the air, even a slight warp in the foam can cause a plane to behave as if it's not balanced correctly. Experiment with your batt position in flight to see what you like best is my advice. I've owned three of these mustangs, my mates have another four at my club, and they all need a little left rudder for straight loops and the tail slides a bit in knife edge. None of them drag the tail like you describe though so I'd suggest something is up with your model, and worth checking everything is straight and aligned.

if all your flight surfaces are aligned properly with their respective leading edge and zero trim, then first check it flies straight upright, hands off sticks about 65% throttle. Then repeat inverted. This will be your best indicator (imho), as to whether your cg is off, or it's something else like incidence out slightly or foam warping etc.

[rifleman_btx]

Try to bring the CG forward about a half inch. If the tail is pointed down in level flight, she's definitely tail heavy, and with a p51 that's exceptionally dangerous with it's tendency to tip stall. Only other thing I can see is might be alittle slow for some reason causing it to fight you. If that's the case might try alittle hotter motor?

[AkumaZeto]

Here it is balanced perfect at 110. I have tried moving it further forward a tad and no diffrence. Its like its dragging its rear around fish tailing everywhere if that makes sense. It does not feel locked in at all.

[AkumaZeto]

Does anyone feel that this frame is squirrely in the air. My Cg has always been spot on and I fly with a Hobby eagle dead nuts on teh cg and I never feel SAFE in the air with this frame. It just feels off to me and always has. I love the way it looks but it is my least flown plain because of these issues.

[Shirty]

Cool, grats on the maiden mate. It took me two flights to figure out that it was a bit slow for my personal preferences and order a new motor. Though I'd agree she's more than fine for scale flying with the stock setup. I'm getting about 115km/hr out of 6s keeping with the stock prop, but chuck a two blade on and you'll be just over 100mph according to others that have done it.