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Member postings for Paul Johnson 4

Here is a list of all the postings Paul Johnson 4 has made in our forums. Click on a thread name to jump to the thread.

Thread: Warbirds Replicas P51 Mustang
14/11/2020 21:22:26


Hey you may be lagging but your still one of the gang...

All pee taking greatfully accepted...

14/11/2020 19:37:23
Posted by Graham R on 14/11/2020 19:35:32:

I have a spare Ripmax Quantum 55 700kv which I am planning to use in mine.

On a 14x8x4...?

14/11/2020 19:34:43

Oh it's one of Richard's kits from long ago.....devil

Really good model guys.....

He he he he'll slap my wrist for that one...

14/11/2020 19:30:33

Da Rat......


14/11/2020 19:23:12

Hi Geoff,

I think you will find even on 4 cell the current draw will be too high.

Don't know what the motor specs are.

I use a 13x7.5x3 on a 650kv with a 4 cell that pulls nearly 50 amps full throttle. This is in my Yak3. Like a rat up a drain pipe but with a 4 cell 3300mah 4 mins is your limit and that's being careful with the throttle, usually 60 to 75 percent.

If you have a ammeter/power meter try some static tests. This can be a little misleading as the motor usually unloads somewhat in flight so okay for a initial try.

Using a 5 cell with a 660kv could be over stressing the blades.

There has occasional blade separation where the 'speed' freaks push them too far.

14/11/2020 17:50:32

Motor selection...

Although thoroughly covered elsewhere in these threads, to save you looking, the standard motor for the FMS 1400 P51 is a KV540.

The first 'mod' for a little more speed was to put a 1mm section of a zip tie under the leading edge of the prop between the backplate and prop. The next upgrade was to change to the KV580 motor.

I have tried both these 'upgrades' and found the KV580 a better option.

Downside is flight time, I like to fly 'scale isn't and very rarely am full throttle. On the 540 could get a good 8 mins out of a 4000mah 4 cell.

Lost 2 mins with the zip tie mod and down to 5 with the 580

All using the 14x8x4 fms prop.

Hope you find it useful.



Edited By Paul Johnson 4 on 14/11/2020 17:53:07

14/11/2020 14:44:31

Hey everyone noticed Nigel has gone quiet...... Mrs must have read his posts.....

Finished sheeting top of second wing... just started on the bottom.

14/11/2020 13:38:05

The 17x9 is on the 1700 fms model and I think uses a 380kv motor on 6 cell.

14/11/2020 12:18:13

That's what I am using..

13/11/2020 15:41:02
Posted by Nigel Dell on 12/11/2020 22:11:35:

Paul I like to live on the ragged edge🤣

Rich I have tried that but to no avail, something to do with the condenser I think😈😂 come to think about it she reminds me of your Kwacker starting up 🤭👍🏻😂

Give that man the DFC and Bar (well at least a pint) for outstanding bravery.

Meanwhile, I am working my way towards assembly of the opposite wing so talk amongst yourselves for a while...

12/11/2020 22:07:03

Ooohhh bet she hasn't seen that post....

12/11/2020 17:37:41

How times have changed....

I can remember pretending to cough when I farted...

Now after this damn Covid-19....

I fart to cover up my cough...

11/11/2020 16:41:52


11/11/2020 16:40:40
Posted by Glynn on 11/11/2020 14:31:41:
I am sending Paul a set of Posh Bits so I hope he tries them.

Edited By Glynn on 11/11/2020 14:32:29

Whaddiya mean a Set of Posh's bits...!!!!!

David.... you finished yet?

Anyway going back a step to the flaps...

I hope this might clarify a few details.

Again this might/should be different on the production models.

When the torsion bar is finally fitted after sheeting, fitting hinges and covering the flap. It needs to be located CAREFULLY.

Before you sheet and a small piece of 1/8" sq balsa as a backstop to make sure of the correct pivot point.


This is where, on mine, the bar needs to be to work correctly.

more tor details1.jpg

This shows the torsion bar side on and you can see how with the flaps deployed will rise into the radiused cut out.

My one has extra cut out as it needed correcting. The white squiggley shows how the back of the 'bat handle' has to align with the pivot point.

more tor details2.jpg

To aid this I added the balsa strip to help location later.

more tor details3.jpg

Edited By Paul Johnson 4 on 11/11/2020 16:40:56

11/11/2020 14:13:35
Posted by Trevor on 11/11/2020 13:39:33:

Thanks Paul. Just wanted to make sure I wasn’t missing something (physically or mentally!).


smileyPhysically i'm good...well kinda but mentally not so surewink

11/11/2020 13:07:38
Posted by Trevor on 11/11/2020 11:05:12:

Paul, any chance of a pic of your prop installation with the spinner cone removed?

Thanks in anticipation,


Edited By Trevor on 11/11/2020 11:06:35

You want to see my Precious naked......????

Oh okay...

prop adapter.jpg

You will need to remove the hex section of the shaft, easily done by first filing the worst of it of then using a drill spin it up and run a file over it to finish.

The spacer is a bit of ally i had about with a 8mm hole in it cut to length but you can get creative with anything with the an 8mm hole in it, stack up some ply discs on an 8mm bolt and spin it up in a drill and sand to required size etc

I used some M3 nuts as spacers instead of Glynns posh bits

prop spacing.jpg

09/11/2020 16:51:20
Posted by alan p on 09/11/2020 13:58:53:

Hi Paul

Keep your precious polished. cool

Which and what size motor/ESC have you used.

Alan p

Hi Alan,

I have fitted the FMS 580 kv and a YEP 80 A ESC.

The standard FMS Mustang uses a 540kv motor.

09/11/2020 12:29:10

Gollum here.....

with the precious......

I just had to fit it.... just had to....

spinner fitted.jpg

I have fitted a set of 1400mm FMS P51 blades.

If you choose this as your setup I found you need to pack the back of the blades about 3mm to clear the back plate. DO NOT modify the blades instead !

spinner with fms blades.jpg

It's soooo damn.... OOO MY PRECIOUS

08/11/2020 09:13:25

Good morning fellow Balsa (that was) bashers.

For those among us that are going down the sound system route.

So far there is two methods to date.

1. Richards..... Easy

As per page 13 of the MANUAL the bottom block of balsa can be swapped for a suitable piece of depron, to the inside of this you can glue the transducer. Fix in place as you would the balsa block, sand to shape and cover as normal.

We have both found that if you try to fix the transducer to balsa/ply the volume is no where as good as a piece of depron.

Also should you need access to the transducer it would be simple to remove using a scalpel

2. Mine....... Not so easy, Why?..... because I cancheeky

Now as you recall I did not glue in the battery box and this is the route I have chosen.

I made two ply side supports which are fixed inside the nose running between the first two formers, these have fitted M4 threaded inserts. Holes were drilled into the battery box sides. this allows me to fix the motor/battery box securely in place but will allow easy removal if required in the future.

This stems from my paranoia of "if I can't get to it.... I'm gonna need to"

I will use the balsa block but have decided to create a circular hole in the block and on the exterior cover this with some very fine stainless mesh set flush with the exterior surface to be painted to blend in but create a sound outlet to try and enhance its tone.

Internally I am going to mount the transducer on a piece of depron affixed just above the balsa block.

I am hoping this will create a sound box to enhance the bass a little.

I haven't tried it as yet but this is my plan.

I will put up a quick video of my findings when I get that far.

But this is what has been completed to date.

Side supports with 4mm inserts glued in place.

battery tray fitting1.jpg

Motor/battery tray refitted.

battery tray fitting 2.jpg

Access available after removing tray/motor.

battery tray fitting 3.jpg

I intend using the tops of the 12mm square section to glue the depron sheet to to create that speaker surface.

Lets hope is is worth the effort!!

3. Method 3

Add your ideas here........!!!!

4. Anybody found a 1/8 scale Packard Merlin?


Edited By Paul Johnson 4 on 08/11/2020 09:14:12

07/11/2020 16:11:30

Jet do to a lesser extent as their turbine rotation is the same direction as most props, let me see if I can find the link its an interesting article.

The main part of the article was it was more natural to move your arm inwards rather than outwards.

Most aircraft the control is central or on the right.

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