Warbirds Replicas P51 Mustang

[Jonathan S]

Quick question. I am looking to start on the fuselage and I separated all the parts and started to look at how they go together. 

 

My first question on this part of the build is which hole does former 2 go in 

 

 

[Eric Robson]

Hi Jonathan, if you look at the side view on the plan you will see the former 2 goes in the front slots and the upper deck former goes in the rear ones.

[Jonathan S]

Thanks Eric, 

 

Ah a basic solution to a basic problem.   I have not got the plan for the fuselage yet. I separated it into bits to fit the desk.  

 

I was just seeing how it all fitted together following Paul's posts.  Maybe I need to tape the plan to the wall. 

 

[Gordon McConnell]

12 hours ago, Paul Johnson 4 said:

Well with the weather nice the P51 had her maiden this morning.

She needed a slight trim with ailerons and rudder but behaved very well.

I have the C of G at 100mm from the leading edge centre and I think that it could be moved back still a touch to 110mm as she wanted to slide in a turn nose down. On the three flights I had it was easily dealt with, with opposite rudder. Obviously no inflight shots/video are available due to being on my own.

She has the Predator 580kv motor and the 4 blade 14x8, on the 4000mAh battery I got a comfortable 6 minutes of flying time with the battery checker showing 30% left.

It flies well on 3/4 throttle and is reasonably fast.

Landing is a breeze with full flaps at 55Deg. It floats in with very little throttle and has no tendencies to roll or nose up when the flaps go down, mine are programmed to extend fully in 6 sec from the transmitter. If you can't do that try it at altitude first just to be safe.

The magnets holding the scoop on worked well and it stayed in place as well as the battery hatch. It was worth adding the rear radiator door not only for looks but for a practical purpose of venting any internal air pressure from the open chin scoop.

 

Jonathan

As this is your first warbird I strongly recommend getting a experienced fellow club member to carry out your maiden flight when your ready and a little buddy box time would also help to have your confidence built up before going solo.

 

Paul, Congratulations on the successful first flight. Your model looks superb. 

[Gordon McConnell]

I finally got restarted on my Mustang after a severe bout of work. 

Finished shaping the wing root fillet fairing. The design of the fillet with the thin ply base and the slotted balsa glued on top and to the fuselage side works very well indeed. Spent time razor planning and sanding it to shape this afternoon. Glad I had a good 3M mask as it created a lot of dust! Put some masking tape on the fuselage to protect it when sanding. Just needs a thin bit of filler to smooth everything.

Now I wonder how that Jetstream got in the shot trying to land in the cockpit......? 

 

 

 

 

 

Then onto shaping the LE and TE of the fin/rudder and the tailplane/elevator. I think I noticed that Paul had used Robart hinges. I had not used then before but thought I should give them a try. Very easy to fit using the jig to drill the 1/8 inch hole for the hinge. The tails are ready for covering but the hinges won't be glued in place until the painting is complete.

Nearly at the covering stage on the wings and fuselage. I have some white Solartex which I have tried on a flap and it goes on well. I will need to be sparing with the paint to keep the weight under control.

 

 

 

 

 

 

[Jonathan S]

On 31/08/2020 at 21:58, Paul Johnson 4 said:

Jonathan,

1. Yes thin CA.... keep some acetone handy...in some nail varnish remover. Removes stuck fingers from balsa...

2. A good wood glue, gorilla or aliphatic this needs to be of the waterproof variety.

3. Drill, clip with side cutters then good ole dremel with sanding drum. Or half round file for the ssssllllooowww version. The 'smile' is a row of small holes filed out with a half round file.

Will discuss cutting to size later, depending on what motor you fit.

I suggest the good old FMS 580 kv and an 80 amp esc.

 

 

Paul,

Did we ever discuss how to cut out the Cowel or cutting the canopy?  

 

Sorry if I missed it. 

[Paul Johnson 4]

21 minutes ago, Jonathan S said:

 

Paul,

Did we ever discuss how to cut out the Cowel or cutting the canopy?  

 

Sorry if I missed it. 

Richard covered the cowl cutting in the manual. I cut mine that way.

The canopy has some well defined lines on it to follow, just trim in stages rather than one go.

I think I covered the canopy or at least my way of doing it.

Just take your time.

 

[Jonathan S]

Next basic question

Have I got the tail post the right way round. 

 

 

[Paul Johnson 4]

Yup

[Jonathan S]

Paul, 

Thanks I was doubting my own sanity.  

I am going to tackle the rear tonight if I can get the kids to bed early.  Cannot find an octopus apparently  he is washing his arms tonight.  But with some tape and clamps I thing I will manage.  

[Tim Kearsley]

Returning to the P51 build after a lull and I'm struggling a bit with fitting the cowl tidily.  I'm finding that if I adjust the cowl so that the motor spindle is central in the aperture, the angle of the front of the cowl isn't the same as the angle of the spinner backplate, i.e. the gap between the front of the cowl and the spinner isn't even, which looks untidy.  I'm not sure how I can improve this.  Is it something we just have to put up with? 

[alan p]

As with all cowl fitting its usually a compromise between accuracy and aesthetics. Use the spinner backplate as your datum for position and clearance. 

Then its down to your judgement.?

[Tim Kearsley]

Thanks Alan.  This topic has raised another question actually:  Has anyone built in any down and/or side thrust into the power train?  My cowl lines up a little better if I add a little downthrust by putting a washer behind the top engine mount bolt.  To those who have flown the model, did you have any thrust angles built in or, if not, did it seem like it needed it?

[Paul Johnson 4]

It flies well without it but the choice is yours. The side thrust is easily countered by use of the rudder on take off and it only requires a touch.

When trimmed she doesn't tend to zoom so if you find the angle helps with the aesthetics then no Biggy.

On aligning the cowl I used a piece of 1mm and formed a disc with a hole in it, used double sided tape to fix this to the rear of the spinner and then the cowl nose and trimmed the cowl to fit that way it lined up nicely. If you zoom into this picture you can see it's a good fit.

[Tim Kearsley]

That does look good Paul.  I seem to have the problem that if the motor shaft is central the spinner backplate isn't parallel to the front of the cowl.  Adding the little bit of downthrust I mentioned earlier helps a little.  I think I need to experiment further! 

[Ron Gray]

You can always add a tapered balsa spacer to the front of the cowl to make that parallel to the spinner backplate, assuming that the cowl outer edges line up that is. The cowl and spinner on my FMS 1700mm P51 don't line up perfectly, annoys the hell out of me but as I don't fly it that much its not really a 'biggie'.

[Graham R]

Looks really good Paul.

[Jonathan S]

Silly question I am mocking up the last bits in the box.  I cannot seem to find a location for these bits can you guys help. 

 

 

 

 

[Trevor]

Fin strake and wing fairings.

 

Trevor

[Jonathan S]

Trevor thanks

 

[Jonathan S]

On 20/02/2021 at 21:48, Paul Johnson 4 said:

Gordon these pictures might help i trimmed the centre web back to allow the panel to fit more upright

Paul, 

Quick question the 45 degree bit of balsa, I take it that is a bit of customised add on and not part of the kit? 

[Paul Johnson 4]

Jonathan,

If your referring to the small angled piece of light ply at the tip of the metal ruler, this was part of the  support for the two formers of the top deck just before the removable hatch, it did sit at 45° and had a plain flat instrument panel piece on top of it. I cut this back and lengthened the cockpit cut out to make the new instrument panel sit more upright. 

This was on my model I'm not to sure what was changed from mine to the production variant but will have a look later.

Edited May 11, 2021 by Paul Johnson 4

[Paul Johnson 4]

This shows how it was and what I removed.

 

[alan p]

Hi Paul

I have a predator 580kv motor, and the FMS 4blade prop, being fresh to electric flight can you suggest the min/max battery size, assuming it will be a 4S and 70/80 amp Esc.

Regards

Alan p

[Paul Johnson 4]

Either 3200mAh or 4000mAh will be fine.