Warbirds Replicas P51 Mustang

[Paul Johnson 4]

Gordon

I have a 5050 580KV running a 16x8x3  4S 4000mAh on  a 62" 11lb Hellcat and gives good scale performance for a 5 minute flight.

Edited May 20 by Paul Johnson 4

[RICHARD WILLS]

2 hours ago, Gordon McConnell said:

Richard, what prop do you run on the 800kV motor on the Mustang? I am running a 16x8 prop on a Overlander Tornado Thumper 50/55 580kV. Performance is adequate but it’s a heavy motor and wondering if the 800kV is a better choice. 
 

Gordon , we may be able to Pep yours up a bit depending on if you using a 2 blade or 4 blade prop .

I am using a 14x8 , four blade prop from FMS which I can shim to get more or less power . 

If you are using a 16x8 two blade the output will be quite different . 

Let us know what you are using .

[andrew exton]

20 hours ago, Paul Johnson 4 said:

The first batch used the FMS Predator 580KV motor with the original FMS 4 Blade Spinner and Prop. Don't use the 4250 800KV on the 4 blade as it is too hot for that prop.

 

 

I’ll probably go with the 800kv  . Never seem to get things right with  3/4 blade props plus 2 blades are easy to get hold of 

 

andy

[RICHARD WILLS]

Yes Andrew, the 800kv equates to 12000 rpm with no prop on 4s , so that means that it would be fair to assume that a loaded but flying model might get close to 10000rpm which is the same as an OS52FS on a 12x6 .   6" pitch props are the most popular and dont produce much of a take off swing , which is easier . 

3 and 4 blade gets trickier but can work well if you get the right combination . 

Luckily , the separate blades on the FMS 4 blade option allow for shimming to change pitch ,so can be fine tuned . 

[Gordon McConnell]

Hi Richard, it’s a two blade. I double checked the model and actually it is a 15x10 Master K- Series airscrew that’s on it just now. It takes some practice for take-off at reduced throttle due to the high torque. 
I do have the FMS 4 blade in the alloy spinner. If I recall correctly it lacked thrust for take-off. 
Using Overlander 4S 4250mAh battery packs. 
Very happy with the Mustang. It flies beautifully. I would guess it could benefit being a bit lighter ( my building and finishing was heavy). But it is great as is. 
Gordon

[Paul Johnson 4]

52 minutes ago, Gordon McConnell said:

If I recall correctly it lacked thrust for take-off. 

I'm using the predator 580kv with the FMS 4 blade and find it has plenty of thrust. I also have the original FMS P51 with the cable tie mod but this is with the original 540KV motor, this puts its performance little below par of the 580KV but better than the original.

How much is its all up flying weight?

[Chris Walby]

I am probably wrong but I thought high pitch props don't work very well at low airspeed. I bit like not much and then whoosh loads of thrush at higher air speed.

 

So if you want low air speed thrust go for larger diameter and reduced pitch + 3 or 4 blade props. 15x10 sounds a monster 🤪

[Ron Gray]

27 minutes ago, Chris Walby said:

15x10 sounds a monster 

It’s a Master, not a monster, but it will be good as a paint stirrer as they’re pretty rubbish props imo.

[Gordon McConnell]

Paul, thanks for the reply. My P51 weighs 2.81kg. The 4S 3350mAh battery is 292g in addition giving a 3.1kg flying all up weight. 
Alternatively, I have been using a 4S 4250mAh battery at 411g. 
 

[Paul Johnson 4]

That's about the weight of mine and she flies well with a 4 blade.

[Paul Johnson 4]

Also has a fixed tailwheel and ground handling is good.

[Paul Johnson 4]

Out of interest this is the 11lb Hellcat flying on a NTM 5050 580KV using a 16x8x3 and a 4S 4000mAh battery 5 mins flying time.

[Gordon McConnell]

Thanks Paul. I will try the 14x8 4 blade again to give a comparison. 
I have a fixed tail wheel on mine. I think it does make the ground handling easier. 

[Paul Johnson 4]

An interesting thing about the P51's ground handling was that the tailwheel was castering for taxi and steered by differential brakes, but then locked by pulling back fully on the stick for take off so our fixed setup does mimic the real one.

[alan p]

Due to circumstances I have sold my Mustang on to a club member, Built and set up as per Richard's instructions. on 4s.

Maidened by new owner, comment from friend observing was "Flew like a dream" Nice one👌 Richard well designed. 

[Gordon McConnell]

Interesting point Paul. It does make sense to design the P51 tailwheel steering that way. Free castoring at low speed for ground manoeuvres during taxy and fixed to prevent large swings during take-off. Pulling the stick back for take-off keeps the tailwheel firmly planted on the ground until flying speed is reached and the stick returned to near neutral.