Geoff's Warbirds Replicas P51 Mustang

[Geoff Gardiner]

On 10/04/2024 at 19:21, RICHARD WILLS said:

Geoff , have you tried just wetting the concave side , but keeping the other dry ?

That's how they get warped in the first place . One side gets damp and expands while the other stays dry . 

Try it and see what happens even without the weight after . 

So... Steaming improved things a bit but still had a bit of a warp.

 

I next tried wetting the concave side but that has made things worse.

 

I have some ammonia knocking around, that I have used for tight bends in balsa before, I might try using that.

 

Failing that, I will cut a new part.

[Ron Gray]

12 hours ago, Geoff Gardiner said:

I next tried wetting the concave side but that has made things worse

Wet the other side.

 

I’ve had the same thing on a couple of models so I just cut a slot through the balsa, across the grain, then glued a lolly stick in the slot whilst keeping the balsa flat. Worked a treat plus I got a lolly to eat. I would advise against Magnums as their sticks aren’t straight and can have facial hair.

[David Holland 2]

Wise words, Ron.

 

😉😉

[Geoff Gardiner]

I hate to admit defeat, so I am giving Ron's lolly stick idea a go 🤞

 

[Ron Gray]

Ah, you should really put them in on edge not flat! Like this:

 

[Geoff Gardiner]

Ah yes, obvious now I think about it!

 

Every day's a school day.

[RICHARD WILLS]

Wood eh ? Funny old stuff . 

You can get Magnums in a three pack for £3.15 . 

You've used two , so raised the value of the P51 by £2.10 

Ive used individual Tiramisu pots for wheel well lining before and it works out more like £2 each . 

Conversely , you can nip into McDonalds and get coffee stirrers for nothing and those little paper cups that you put the sauce in (which I have yet to discover a use for ).

Is this going to be a new kind of modelling Ron ?

A bit like Kevin Costner using ski boots to walk on the sea bed in Water world ?

Maybe we could make a man carrying model with stuff from the recycling bin ?

 

[GrumpyGnome]

I have a shoe box pretty much full of coffee stirrer sticks. Neither my wife nor I take sugar but replenish my stock each time we visit a coffee shop from one of the large chains...... They used to be used extensively to reinforce and repair foamies, now mainly as epoxy stirrers, so stock levels are high.

 

Somehow, I've managed to accumulate quite a number of pieces of carbon in various sizes to use as reinforcement...... probably salvaged from dead models as I don't recall ever buying any.

[leccyflyer]

Yep, every time I buy a cup of overpriced brown liquid from one of those chains  I collect an appropriate number of these very useful stirring sticks, despite taking neither sugar, nor milk. They are so useful in many ways - perfect leading edge reinforcement for 6mm depron wings, superb paint and epoxy stirrers and applicators and clipping the end off makes for nice lightweight control horns. The chain doesn't lose out, since I'm partaking of neither sugar, nor milk and they would go in the bin anyway. I've nowhere near a shoebox full though, maybe a dozen on the go at any one time.

 

Don't eat Magnums these days but a bulk buy of lolly sticks from eBay is very cheap, with hundreds in a pack and lasts a long time. These are useful as stirrers and applicators, plus local hardwood reinforcement - nice hardpoints for mini and micro servos into balsa and foam.

[Geoff Gardiner]

Do you think I would get 'rumbled' if I got some coffee stirrers as I don't take milk or sugar - nor drink coffee?

 

[leccyflyer]

£3.49 for 200 on eBay - that's less than tuppence each.

[RICHARD WILLS]

Tuppence ? Thrupence ? A tanner ? 

Half a crown 

2 and 6 a pound  

Its a lost world isnt it ? 

(Sorry Geoff ) 

[leccyflyer]

Less than a penny each if you buy 1000 at once....

[Geoff Gardiner]

This is my take on fitting the radiator on the underside of the wing.

 

first I added some extra width to the base that gets glued to the wing. Instead of sanding a V shape on the underside to fit the dihedral, I cut it in half and sanded the top flat.

 

 

 

Then I added some extra width to the radiator and sanded to shape.

 

 

 

 

Here I really struggled to get the angles right to blend with the vac formed front scope - it just didn't look right.

 

 

So I tried gluing on some scrap balsa and sanding to shape.

 

 

 

 

I think I will go with this option.

 

More later...

[Geoff Gardiner]

A bit of filling and sanding of the wing today.

 

It's getting closer to being finished!

 

 

 

 

More later...

[Geoff Gardiner]

Things had slowed up a bit recently but I have done some more:

 

I have added a radiator vent

 

 

 

I have also covered the wing with brown paper. Covered, painted and fitted the flaps and ailerons.

 

 

 

The brown paper is sealed with a thin coat of PVA.

 

I have fitted the aileron linkages.

 

 

I am using two servos for the flaps so I had to reverse one of the servos as I will be using a single DB9 connector for the wing. This involves swapping over the two yellow wires connected to the servo motor.

 

 

And then swapping over the two outer wires (red and black) that are connected to the potentiometer.

 

 

 

 

Finally I have added a strip of balsa to neaten up the battery hatch/fuselage join.

 

 

More later...

[Nik Harrison]

I'm intrigued about the picture of the two servos that appear to be driving the flaps.  How does that work?

[Geoff Gardiner]

Nik, I wanted to use a single connector when attaching the wing and am going to try DB9's.

These give you nine pins to play with and as I have 6 servos in the wing (2 for ailerons, 2 for flaps and two retracts) this gives me 18 wires to connect.

In order to do this I will pair them up.

The electric retracts are fine with this, as are the ailerons (when one goes up the other goes down). The flaps however need to go up and down together and in order to achieve this, on of them has to be reversed. As they are sharing the same channel on the reciever, I can't simply reverse one on the transmitter (they would need to be on seperate channels) So I opted to reverse one manually by opening it up and switching wires around.

I hope that made sense!

[GrumpyGnome]

They don't look like typical torque rods...

[Eric Robson]

I usually mount the flap servos the same way.

It saves reversing the wires.

 

 

 

 

[Chris Walby]

9 hours ago, Nik Harrison said:

I'm intrigued about the picture of the two servos that appear to be driving the flaps.  How does that work?

I could be wrong, but I think Nick wanted to know how the flaps work mechanically? As in push pull to rotation of the flap.

 

If not I am interested 🙂 

[GrumpyGnome]

Me too... hence my comment that they don't like like 'normal' torque rods..

[Nik Harrison]

Mechanically working the flaps was the reason for my question.

[Ron Gray]

If you look back to Geoff’s post on the 14th Feb he shows the flaps in construction, that should show how they work. 

[Eric Robson]

I thought of giving the information about the flaps but feared I would be shot at dawn by Richard or the boys.