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1/18 Airacobra 1 - AH601


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Hi again

 

I was doing an experiment and it got completely out of control...

 

In thinking about what to do next, I am a bit limited in it needs to fit in a 55cm sq display cabinet and I love working from drawings but apart from whats in Aircorps Library they are thin on the ground. I looked at what's in there (which is loads) and went for the, I think much maligned and forgotten P39. Technically advanced and actually an interesting airframe to take on given the mid engine & nosewheel, plus the doors to the cockpit allow all of it to be seen 😎 I sort of got the bug for it..

 

in preparing & thinking about it, I was worried about the noseweight needed to stop it being a tailsitter so I thought 'what if I 3D print the tail section..' - this seemed straightforward given the fairly consistent oval cross section..

 

..well in 2 days I had designed the fuselage based on drawings... now I am no Rhino expert but using some of the most basic shape forming processes got me here as can be seen by the messy 'creativity'..

 

buAaTp.jpg

 

..I can't do complex shapes like the fin tip, or fillet, but basics seemed to work..

 

..I also needed a subject, and I think you guys and I might be getting a bit bored with bare metal so while it will be skinned, it will also be painted.. My last two models were USAAF so this one will be AH601 of 601 Squadron. They operated the P39 (P400 version) for a short while and actually only completed one combat mission, but nonethelesss, it works for me..

 

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I was also curious about what, if anything the RAF did to lend lease aircraft in order to make sure mine was accurate - I needed look no further than the Air Ministry Pilots notes... embelished with lovely pics of the wireless fit and the sutton harness..they also carried a 20mm instead of the 37mm prop cannon..

 

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..having got into a bit of 3D design, where I previously did wheels, spinners etc for my other models I thought why not try getting a printer and trying that yourself too, so after watching Youtube a lot I settled on the Elegoo Saturn 2 and 8K resin printer which with all the stuff including a wash & curing station came in at about £800. I think this will open up the world to my model building and actually will be a business tool for airscale as I look to grow it. Its a steep learning curve, but I just made my first print of the spinner, the fishtail exhausts and the 20mm cannon..

 

SFmfDU.jpg

 

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..the detail is incredible and I am very happy with this for my first calibration - just look at the cooling fins on the 20mm - this is about 1.5mm diameter...

 

CYsW1g.jpg

 

..the other thing that has kept me busy is preparing the PE for the model - I have never done such an extensive set and this lot is about 900 parts across three nearly A3 sheets..

 

every one is from the factory drawings which is what gives me the most satisfaction..

 

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now as for printing the fuselage parts, I was given a Flashforge Adventurer 3 for Xmas by my son in law and the bits were printed in PLA which is horrible to work with - it doesn't sand very easily but is incredibly stable & strong. I have now got some HIPS which I am told is better so will try that. The parts were broken down into substructures which fit within the 15cm x 15cm x 15cm print bed and took about a day to print. I also designed in square holes with 5.3 degrees dihedral to accept brass square spar sections

 

..the upshot is that in 3-4 days, I got a structure that is strong, light, accurate and represents what would have taken 6 - 8 weeks using traditional methods..

 

..enough waffle, I guess you want to see it..

 

39Ct7S.jpg

 

so, after a few days I had had a go at a few other things - mainly learning how to modify shapes - I found a tool in Rhino called 'Cage Edit' which basically allows you to for example create a ball and deform it so much it becomes a wingtip ..any competent designer would have a coronary if they saw what I was doing...

 

I think the problem with 3D is knowing when to stop..

 

xRvdpb.jpg

 

I reprinted a new nose and tail that incorporated a nosewheel mount and keyed & slotted areas to accept a new rudder & stabilisers - also printed these in resin not HIPs

 

DT9xgu.jpg

 

..wings were done in sections to as close as I can get the tips - again with brass mini spars..

 

QOJegu.jpg

 

..and a quick skin with P38 and a shot of primer and in a week I had an airframe.. ridiculous really..

 

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..onto the PE and the floor first which on the real one is many layered panels, so as per the original thats how this was made..  a small plunge moulded bit was made for the nosewheel cap..

 

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..the seat was next, this had some PE and the rest scratchbuilt - the rolled edge was made of fuse wire..

 

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..the rollover structure was a laminate of PE onto a 3D resin bulkead and the wholde thing dressed with Meng nuts..

 

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..the trim control box was again PE and resin parts.. just resting together here..

 

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..and it's good to be back in the 'pit

 

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and thats it for now - about 12,000 more parts to make..

 

TTFN

Peter

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  • 3 weeks later...

evening ladies :) thanks for all your kind words

 

I have been busy doing airscale stuff for the new HK A20G so not too much time for building...

 

that said, I have a few bits done - this is a nice shot of the P39 floor and shows the tunnel through which the driveshaft travels. the control yoke has a fitting that also allows this so is a bit complex under that boot..

 

note the tunnel flares out at the point it meets the column so that needed doing and the big structure next to the column is I think an emergency hand crank for the U/C..

 

ako0cx.jpg

 

..I made a buck from brass and P38 and shaped annealed litho for the tunnel..

 

iPaEc8.jpg

 

..the crank was made from PE with a brass bush and a bit of filler..

 

QQXpaT.jpg

 

..and the tunnel can be seen here, not that you can see it with the seat in place..

 

P2zN8T.jpg

 

..other bits that were made include the forward bulkhead that has box like sections for the rudder pedal area and the seat mounting struts, the forward tunnel and the blank for the switch / instrument cluster between the pilots legs..

 

msegAQ.jpg

 

..also made the rear deck - again this is why I spend so long making PE as it makes for easy assembly..

 

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..and the bits sort of where they go..

 

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..and thats it for now, hopefully get a bit more done soon

 

TTFN

 

Peter

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Even with limited time you've made some great progress with some exquisite details added. 

 

Where do you get your litho aluminium from Peter? I often use regular aluminium sheet for parts but I think I might be missing a trick. 

 

Richie

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Hi folks :)

 

Beautiful weather here in the UK for a change so I decided to ignore it and spend some time at the bench 😎 modellers are a wierd lot..

 

On 6/3/2023 at 10:27 PM, RichieW said:

Where do you get your litho aluminium from Peter? I often use regular aluminium sheet for parts but I think I might be missing a trick. 

 

Richie

 

 

Hi Richie - I get it here - I have no idea how to navigate their website, but the stuff I buy is called 12 X 16 X .0055, SC Plates in a box of 100 sheets; Long Run Premium

 

I bought 100 sheets a couple of years ago and have a lifetime supply :)

 

 

..change of tack, I started the nosegear bay...

 

pyvo7U.jpg

 

...the big silver thing in the middle is a chute for the cannon shells, but I had to cut the top off as I need to get a big lead weight in all the remaining space in the nose..

 

jVhWDn.jpg

 

..and the other wall with a main circuit box..

 

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..dry fitted..

 

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..and when complete the whole assembly will slot into the nose..

 

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..shot it all with MRP zinc chromate..

 

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..and weathered it a bit..

 

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..and taped together.. some compromises needed to be made for the nosewheel leg mount which in my model is in the upper fuselage, in the real one it is below the propshaft which travels through the star shaped thing on the right above..

 

wr9x33.jpg

 

..will work out fine and no-one will ever know 😎

 

vwXdzo.jpg

 

TTFN

 

Peter

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  • 2 weeks later...

evening ladies :)

 

been getting a little more done...

 

..the rudder pedals and structure is nicely detailed in drawings..

 

CF8tzw.jpg

 

..and from here a bunch of parts were made up, including pedals, hangars, brake cylinders and the support beam..

 

O9qoUP.jpg

 

..which were assembled, painted and given some scuffing..

 

T3qR0N.jpg

 

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..that structure then mounts to a forward bulkhead with 'bins' in it for the pedals to traverse into..

 

MAke0P.jpg

 

..I also made up the control yoke and cover from brass and thin sheet lead and while the paint was out painted everything what i thought was 'bell green'. I tried the hjairspray thing and had painted everything YZC first but for some reason it didn't make any difference and the MRP paint is well and truly on there...

 

CUgzOu.jpg

 

..the canvas cover was quite hard and sits under a retaining clamp as per the original - when the yoke is installed I will tidy up the join at the stick..

 

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..painted and scratched up the seat..

 

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..and the main structure is starting to come together..

 

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lots still to do in there

 

TTFN

Peter

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evening folks :)

 

 

On 6/24/2023 at 12:04 PM, Gondor44 said:

Very nice, but why did you install the piston like devices from the pedals to the bar upside down?

 

Gondor

 

 

good spot - perhaps I was standing on my head at the time :)

 

..it's an easy fix so thanks & will do that..

 

so a random wander around what has been going on lately...

 

I 3D printed a buck to vacform the windshield, upper canopy and rear glass and then filled the buck, sanded, filled a few more times until I had a master good enough to cast in resin...

 

IIHF2v.jpg

 

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I will try and get this vacformed as it is too big for my little dental machine..

 

..then I made the instrument panel mounting frame and two emergency door release handles..

 

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..then I built a small house..

 

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..in fact, it is a jig to hold the cockpit skin as I thinned it so much it was transparent, so with it in place on the airframe, I built a jig around it so I know when I am done it will fit right back into place..

 

..then I skinned the inside and started detailing it..

 

fSKatw.jpg

 

..on this side is the throttle mount sticking out into the door aperture..

 

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..and the other side..

 

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..I rolled out a strip of lead until it was super thin and then stuck down templates for all the seatbelts needed for the RAF sutton harness..

 

7KiSm5.jpg

 

..these were then assembled with PE hardware.. here seen with maskol on the PE bits..

 

qI27lu.jpg

 

..and painted & added to the seat..

 

R4Lyuh.jpg

 

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..the seat was added to the rollover bulkhead, and that bulkhead added to the skin in the jig - this gave it enough strength to be able to cut most of the jig away..

 

JqzVZE.jpg

 

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..and finally, these are all the components prepared for the throttle quadrant..

 

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..and after assembly..

 

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..and where it sits on the mount..

 

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..I should get the instrument decals next week, so soon I will get to my favourite bit of any model - the instrument panel

 

TTFN
Peter

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evening ladies :)

 

Well, I got to my favourite part in the build - the cockpit & instrument panel 😍

 

I don't know why, but I have always enjoyed this the most, I guess thats how airscale started..

 

I just got in a groove so no in progress pics, but the parts are made from PE, 3D, custom decals scaled up from our own airscale ones (of which I have about 100 sets now eek), wire, plastic, metal, some hiroboy switches and some of our metallic placards

 

...first up a control box on the left side of the cockpit which includes a bunch of circuit breakers..

 

KvoUHq.jpg

 

..next, the centre console which includes an RAF radio fit - no idea what it is but its in the Pilots Notes pictures

 

62aqBR.jpg

 

..the left hand instrument panel switch panel & mount..

 

M6YdYt.jpg

 

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..then the right hand side panel & mount including UK oxygen fit..

 

45psrN.jpg

 

 

722Seq.jpg

 

..for the main instrument panel, it sits up and proud under the windshield and I think a lot of gubbins can be seen (unless covered by a canvas boot thing) so I made it as it can be seen..

 

VrwwMH.jpg

 

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ygaeZE.jpg

 

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..loved doing it and think I could just make these instead of whole areoplanes..

 

TTFN

 

Peter

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  • 3 weeks later...

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