1/18 Curtiss P40C - Finished :)

[brahman104]

Thanks for the "shop" photos Peter! Wow, that proxxon mill is tiny! But you're certainly doing very well with what you've got to work with.....clearly I have no excuses! 

 

Another brilliant update, the gear legs are looking absolutely exquisite! 

 

Craig

[JayW]

Another thing Peter - I used to make alot of use of my Unimat mini-lathe and end mill combo, as you know.  Not without alot of effort and pressure - it takes time to set up, and cut raw material stock (often an adventure all by itself), and then machine it.  Bits wear out and need sharpening, the motor gets hot and must be allowed to cool down.  It makes a terrible mess of shavings and chips.  I spent much coin on the motor which broke down too frequently.  And I have injured myself at times (mostly deeply skinned knuckles from a high rpm chuck).  And a failure can be heart breaking, if it happens after hours of machine time.  Frankly it's all a bit of a PITA, and I had to sort of gird myself whenever I started a machining project.  But I have produced some parts that I am proud of (like landing gear wheelsets and tires). 

 

But 3D printing has allowed me to shy away from machining for most applications, where before that was the only good option I had.  I feel kind of guilty about it.  Kind of the easy way out - just design digitally, get someone to produce it in 3DP, and pull out the wallet.  I continue to respect actually scratch building a part.  We've had this discussion before...

 

Interesting that you have chosen the machining option for those gear strut parts.  Bravo.  What is the maximum diameter stock that your lathe can handle?  My Unimat can only go about 2 inches in diameter.  I have a shim I can put under the head stock, to handle slightly larger material, but realistically it doesn't work well.  The chuck jaws go to their limits, the translating table for the bit runs out to its end, etc.

[scvrobeson]

You are a wizard when it comes to creating parts and details. That's the only explanation.

 

 

Matt 

[KiwiZac]

I've not commented much as I think I used up all my superlatives several pages ago. But rest assured this Kiwi is checking in on every update and thoroughly enjoying the ride!

[airscale]

evening all

 

Thanks for your kind words - it is you guys that make me push my standards up

 

On 6/22/2022 at 4:46 PM, JayW said:

Interesting that you have chosen the machining option for those gear strut parts.  Bravo.  What is the maximum diameter stock that your lathe can handle?  My Unimat can only go about 2 inches in diameter.  I have a shim I can put under the head stock, to handle slightly larger material, but realistically it doesn't work well.  The chuck jaws go to their limits, the translating table for the bit runs out to its end, etc.

 

Hi Jay, truth is I like making them on my machines, it's the only real call I have to use them, so I always learn something I have no idea what my mini lathe can hold, the largest stock I have is about 15mm - I think it has a standard sized chuck so I guess its probably the same limitation as yours. I would like to do much more, and I love watching machining on youtube - this guy is my hero - all the kit and all the skills to go with it

 

 

 

 

so, on to some P40 stuff..

 

..in trying to get the basic airframe done, it was time to move onto the landing gear housings - unlike most aircraft of the period, the gear is mounted to the wing, only the wheel goes in a well. This means the gear leg is in this bulbous housing full of lovely compound curves...

 

 

..I couldn't find the drawings that detailed the shapes and was trying to piece together component cross sections when I contacted Waroff for help. He literally knows every nut and bolt of a P40 and soon put me onto this drawing...

 

 

..it has all the cross sections and in combination with some others, I could scale aand create them all in plastic card to make a master for vacforming..

 

 

 

..with both of them done, I sprayed them grey so when I slather them in filler and sand it back, I stop when I hit the grey..

 

 

..a quick spin in my little vacformer...

 

 

..and I had some copies - I used quite thick card as they need to be skinned so need to take quite a bit of pressure as the metal is worked, this meant the contours are a bit more vague - I might pull a thinner copy and see if I can improve them..

 

..also the tops of the nosecaps didnt come out as it's too much of an undercut so these will be done seperately..

 

 

..I was getting all set to add them to the wings when I realised there is still way too much to do to the gear bays while I have open access

 

..I had just made two big circular openings as the wheel wells will have canvas liners, but as you can see here, there is one visible bit of structure that needed adding..

 

 

..this meant chopping out quite a bit and adding that wall and the upper wing skin & stringers (Kurok was right! )

 

 

 

..this was all then primed and painted.. I had read that zinc chromate was mixed with green for airframe parts vs the more cockpity green in the interior, so I made a mix with a more yellow hue..

 

 

..the circular opening for the wheels needs defining so a subskin was made, this has a lip going into the well

 

..I use aluminium plumbers tape on a bit of litho so I can tape the skin down and CA a strip of litho to form the lip, safe in the knowledge it won't stick to the tape..

 

 

..the panel also had slots cut in it for the retraction struts..

 

 

 

 

 

..and the gear housing sort of goes here..

 

 

 

..still, loads to do, but the important thing is to get the build sequencing right so I don't build myself into a corner..

 

TTFN

 

Peter

[scvrobeson]

Always sublime and inventive posts Peter. Love watching your process as you create a new model from nothing.

 

 

 

Matt 

[Thunnus]

Fantastic fabrication, as usual, Peter!  It's fascinating to witness the ability to transform basic shapes into complex mechanisms.  Truly a gift endowed to just a few.

[JayW]

Vac forming - You have it all Peter.  I must develop this capability myself!  Well done sir.

[waroff]

On 7/2/2022 at 11:18 PM, airscale said:

 

..I had just made two big circular openings as the wheel wells will have canvas liners, but as you can see here, there is one visible bit of structure that needed adding..

 

the wheel pocket made in waterproof cotton cover the wheel bay entirely.

There was a little pocket for the arms and jack, so nothing was visbible.

 

 

 

 

 

 

note the edge of oleo strut LDG inboard fairing is straight until the wheel bay, not 45° cutout

[airscale]

evening all

 

Thans for stopping by & thanks especially to Waroff for those incredibly helpful pics I noticed a few things as a result, particularly the shapes of the early fairings..

 

I had a fantastic day on Sunday, having spent the morning crawling all over The Fighter Collection's P40C G-CIIO. The team were really helpful, taking the covers off, opening the cockpit and even dropping the flaps!

 

I took 300 pictures of every inch of the airframe and cleared up many mysteries in realtion to what a drawing says and what real life looks like..

 

just a few here..

 

..got lots of the cockpit..

 

 

..lots from angles you just don't see unless you have access - see the spine panel layout & rivet patterns..

 

 

..and lots up close and personal in places the internet just doesn't get to..

 

 

..I will have to work out a way of sharing them for other builders..

 

anyways, when I left you last, I had vacformed the wing gear leg fairings..

 

 

..well, I didn't take any in progress pics (slaps wrist..), but these are now fitted, blended and most of the basic internal structure added...

 

 

 

 

 

..clearly, still lots to do but happy enough for now..

 

..next up was assembling the PE I made for the wing part of the flap structure - the plan was to drop these into the space left when I skinned the top of the wing

 

..complex assemblies with a lot of parts, but both were assembled over a couple of days..

 

 

 

..the torque tube slides along to raise & lower them - something I learned from the Duxford guys..

 

 

..before I could assemble the big panel with holes in it, I had to prime and paint underneath it so everything was given a basecoat... after that the little strips were added which are part of the individual rib pressings on the real one..

 

 

..once finished, these assemblies didn't drop in as expected, well they did, but the trailing edge of the wing skin was a bit wonky and it would have doubled the thickness, so I chopped the skin off and just let the flap structures into the wing..

 

 

..these were then blended in...

 

 

..and from underneath..

 

 

 

..starting to get closer to working on the wing fillets, which is the final major shaping / sanding - then I will cut out the ailerons and start skinning the wings..

 

 

 

TTFN

 

Peter

[JayW]

Awesome work Peter.  Nobody will have a P-40 like this .  Not even close.  Wish I could go to Duxford!  

 

[brahman104]

Tremendous Peter! It already looks 90% finished on that underneath shot!  Nothing better than being up close and personal with the real deal.....

 

Craig

[tomprobert]

That really is so impressive, Peter!

[KUROK]

Sweet!

Yes, I'd like a copy of your Duxford photos for reference if possible.

 

One comment:  The landing gear fairing on the inboard side, there is no hard edge as it comes to the wheel well.  It tapers all the way down to the wing by the time it gets to the wheel well hole.

[waroff]

On 7/19/2022 at 4:34 PM, KUROK said:

One comment:  The landing gear fairing on the inboard side, there is no hard edge as it comes to the wheel well.  It tapers all the way down to the wing by the time it gets to the wheel well hole.

 

 

to compare with pics