Airfix 1:72 Red Arrows Hawk & Gnat with an LED light the front

[Cheshiretaurus]

EDIT 8th March 2015 Gnat build was an after-thought Click here to skip to the Gnat build

Thought I'd do a Red Arrows Hawk gear up on a plinth with one of the cheap kits I got during the recent Airfix sale.

I wont do a thorough WIP thread for this as we've all seen Airfix Hawk builds in the past, so I'm just going to show the fitting of the LED then later I'll put up some pics up when I attempt to mount it. (Thinking of an acrylic tube up the jet pipe for hiding the wires in for that bit)

Anyways picked up some 2mm 'lighthouse' type white LEDs on ebay a pack of 10 including resistors was had for less than three quid from a model railway supplier on there.

The LED body is 2.5 x 4.8mm and 8mm long so comfortably fits in the nose.

Routing for the leads will take it under the cockpit floor, This creates a problem as the floor fits flush to the inside of the fuselage so I need to make room for the leads, 2 groves were filed under the floor to take them. the leads are only 0.5mm thick so not much filing was needed. Also to keep the LED central the 2 groves were filed either side of the centreline 2.54mm or 0.1" apart, this is the pitch of the Leads on the LED and is also the standard pitch of most electronic components too. Original plan was to solder the wires to the LED aft of the rear cockpit bulkhead but once a step was bent into the leads to raise the LED body to the correct height and get the body forward enough the ends of the leads then reached to just under the drivers butt, not quite far enough. so the wires had to be soldered on there and a bit more plastic filed away at that point to accommodate the join.

A 'V' was filed into the rear bulk head and the plastic under the slot in the front bulkhead removed for the wires and leads to pass through.

Leads were CA'd to the bottom of the floor and wires secured to half way up the rear bulkhead. A test fit was made and final adjustments made to the LED body to line it up with the landing light position.

A check was made it was centrally aligned was made too.

Other fuselage half fit was checked... all good

Nose wheel door should cover this up well enough.

To stop light spilling into where it shouldn't the inside of the nose had been painted matt black and the LED was also painted except of course the tip.

The vertical slot on the front bulkhead will be covered with a bit of plasticard before I'm done then painted black too.

Although I'm building this gear up I think the LED could also be fitted gear down but part of the nose gear leg would need to be filed away for the leads to fit past if you see what I mean.

I'm going to put the resistor in the mount rather than in the model so it can be changed to suit whatever power supply I'm going to run it off. at the moment its running on a big 3amp 12volt supply I've had for 25 years or so since the CB radio days and isn't really practical for a display mount.

Will post more pics when I try get it on the acrylic mount.

Thanks for looking

Mark

[Black Knight]

Interesting.

[Hawkkeeper]

novel idea, looks neat so far.

[perdu]

not that you are in the slightest bit mad of course

Great idea and looks to be the ideal way to execute it, nice one Mark

[phildagreek]

Good effort.

[Fritag]

Always inventive & always interesting Mark.

Whats next? Strobe lights in 1/72?

[Cheshiretaurus]

Whats next? Strobe lights in 1/72?

Wouldn't rule them out....

[geedubelyer]

Hi Mark, very creative stuff this, good job. The head-on photo looks great.

Any problem with heat build-up from these tiny lenses?

Wouldn't rule them out....

Fibre optics directed from a flashing led in the belly of the beast? Now that's got you thinking has n't it?

[toms111s]

This is very interesting, it adds another dimension to a model to see it lit up. Looking forward to seeing it completed.

[Cheshiretaurus]

Any problem with heat build-up from these tiny lenses?

Doesn't seem to create any heat, there is only 35mW in the LED in this installation and LEDs are pretty efficient at converting power to light so not much excess power to dissipate. No noticeable problems.

Fibre optics directed from a flashing led in the belly of the beast? Now that's got you thinking has n't it?

Was thinking of optics like that using stretched sprue in the way it tapers as it stretches away from the cold sprue to make a fine tip and polish each end. Next for an authenticity thing a small circuit to flash the LED in the profile of the strobe, this would be something like 1-4 quick succession flashes then a short period of a second or two before repeating. There are on the market some single chip microprocessors of just few of mm in size that would easily fit in a model control the LED on and off. It would require a short bit of simple coding to run through the cycle. Something I've not done for about 15 years but would be possible.

That would make an interesting conversion!

All good stuff for a future project maybe.

[Flying Badger]

Cheshiretaurus.... that's exactly how I'm doing it on a red arrows synchro pair of 1:48 Hawks - PIC chips for the flasher controllers for the various nav lights etc and an LED for the front lights plus maybe a coloured LED in the tailpipe to light the acrylic tube blue or red (like smoke).

Even at 1:48 the wings of the hawk are very thin up near the tips so the LEDs would have to be tiny surface mount components - so fibre optic for the red/green lights and white flashers will be used to overcome this - also planning on silicon moulding the full wing tips and then casting clear resin whole wing tips so as to avoid having to try to get a perfect join between the grey plastic and clear parts for the tip lights on both models.

But whilst I've got the kits and the electronics on the shelf, that build is a long way down my projects list.

So doing this in 1/72 is very impressive and I'll be following how it goes to inform my build.

FB

[Cheshiretaurus]

Flying Badger

Was looking at PICs (PIC12F675-I/P in particular only has a 35 word coding vocab, I can deal with that!) Should do the Job, Surface mount maybe with the obligatory ancillary components, not sure if PICs have an onboard oscillator these days and maybe a couple of transistors to drive the LEDs unless the pins are able to source or sink 20mA then could do it directly.

Casting clear wing tips, like that idea.

[Flying Badger]

Some PICs have an oscillator some don't. Not a big issue without.

Most of the PIC projects I've seen start with a flashing led as a test script and they nearly all stick the LED one of the pins - but your best checking the max current the PIC can sink on each of its I/O pins even though 20mA isn't a huge amount of current.

Clear wing tips.... was planning that this would let me drill small holes from the mount side (where it would be glued to my original wing) that I could thread the fibre optic into and thus get both coloured tip lights and the strobes into such a small space and to get them placed just perfect (with multiple copies so the inevitable screw ups aren't an issue!).

FB

[noeyedears]

i did this in a 1/48 hawk kit but 1/72!! this will be something to see.

[geedubelyer]

Hi Mark,

Just reading a copy of SAM and saw an ad from Raven Scale Models. They offer a lighting kit for possible future projects?

See here:http://www.ravenscalemodels.com/beacons_model_lighting.html

Cheers.

[Cheshiretaurus]

Hi Mark,

Just reading a copy of SAM and saw an ad from Raven Scale Models. They offer a lighting kit for possible future projects?

See here:http://www.ravenscalemodels.com/beacons_model_lighting.html

Cheers.

Absolutely brilliant ideas there. never thought of using a reed switch for control or attaching an led to the fibre with heat shrink tube, one of those nice simple solutions,

£25 - well worth it!

[Winenut]

That looks amazing.

what a great idea!

[Cheshiretaurus]

Just a quick update, started painting with HU238 Red Arrows red, first thin coat went on both upper and lower surfaces yesterday. Today so far I've just done the 2nd heavier wet coat on the upper surface.

Little problem I might have is how to get enough paint in between the fuselage and the air intakes without over doing the surrounding area, suggestions? Thought about a fine hairy stick but I'd prefer to airbrush them somehow. Next time I think ill paint that bit before fitting the intakes.

Still not decided which serial to do. The decal sheet has serials for XX227, 242, 264, 266, 306, 308, 319 322, 323 Does anyone know if any of these airframes have any special significance to help me decide?

Thanks for looking

Mark

[Fritag]

Smooth looking finish there CheshireT. Neo at work?

I have no particularly insightful solution into painting the intake/fuselage gap I'm afraid.

That said I did have something of the same issue on my JPs - and I tackled it as best i could by dialling down the compressor pressure so I could get the Neo in close and by using judiciously placed post-it-note masks to keep the paint off the surrounding areas. I kept the edge of the masks off of the surface (rather like when spraying a soft edge camouflage) so as to avoid ridges. It was a pain but it worked.

I do remember thinking that there must be a better way mind you....

[Cheshiretaurus]

Smooth looking finish there CheshireT. Neo at work?

Aye Neo on task, have done the 2nd coat underneath earlier today and have just completed the 3rd upper surface coat, Think it will take 4 coats all together. Getting a bit better at spraying gloss these days since my cock ups experience with the Cherokee and Vampire, plenty of thinner and low pressure (15PSI).

Might try the post it note method in a few days once the main coats have dried.

[A6-EHJ]

Very nice

[geedubelyer]

That's a nice glossy finish Mark. Good job.

[Flying Badger]

Post it note method?

[Cheshiretaurus]

Post it note method?

It was a suggested method by Fritag to try to stop too much paint going on the surrounding area whilest trying to get some paint deep into the gap between the intake and the fuselage.

tried it last night but have resorted this morning to a fine hairy stick loaded with airbrush thinned red.

see how that looks when its dried.

[Flying Badger]

I see.

Thanks... might have to try that when I need some fast masking.

Looking good so far.