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Composite Warbird Build 1/7th P-40E Warhawk

Old 02-15-2012, 12:53 AM
  #151  
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The engineer in me likes to set productivity benchmarks. The modeler in me prefers to rise above.

Main fuselage mould sections are prep'd and gtg. If you're interested in this sort of thing you might find it interesting that each section was fully prep'd individually and as they were assembled, additional thick paste wax was applied to each flange so that as they were bolted together (from the centre, outward..) the fresh paste was extruded from the seams.

I then ran a Qtip along the fresh wax and smoothed it into the seam. After it had hazed, I carefully buffed the areas to sheen again. Voila - I hope you can see the results clearly in the pictures. I don't know how I might have got them any better...

...another day, another day closer...






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Old 02-16-2012, 12:56 AM
  #152  
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Alright - here's the straight dope - sometimes you win, sometimes you lose, but you always learn... lol

The epoxy was great, although I'm glad I got the slow hardener! Almost the consistency of water initially, it wetted out superbly, but when it kicked, boy did it kick! (cost me a new brush arghhh)

I also thought that my patterns were pretty nifty, but I should've paid closer attention and registered them in one place and not two. There's mismatch on this one that there won't be on the next, but it should blend in with an airbrush in about 2 minutes.


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Old 02-16-2012, 02:12 AM
  #153  
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Old 02-16-2012, 04:46 AM
  #154  
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Mixing tempera powder in larger quantities in advance allows easy mixing into resin prior to adding hardener. The larger scale is great for mixing epoxy and hardener with 1 gram precision. The smaller scale I used for mixing powders because of it's 0.1 gram precision.



The dark brown is 33% white into brown.
The light brown is 5% brown into white.



Perhaps this misfit will be best camouflaged for a nudist colony! It's kinda funny in person. )



I've used 3/4 Ounce cloth in the sharp corners, and the surface veil again, in the tight spots here.

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Old 02-16-2012, 10:40 PM
  #155  
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OK, so it's 3/4 Oz cloth in all the tight spots. This is followed by a layer of 9 OZ cloth all around and overlapped in some critical areas like around the firewall and wing saddle etc.. Then it's all wrapped up with a final layer of surface veil.

You like??







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Old 02-17-2012, 06:10 AM
  #156  
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18 hrs so far...but here's two pieces in the bank

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Old 02-17-2012, 04:23 PM
  #157  
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For my next trick, and with a little bit of luck, I will demonstrate a bit of the assembly plan that I designed into this mould more than 5 years ago now....patience my friends, patience...

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Old 02-18-2012, 02:01 PM
  #158  
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The chin plate is 2 layers of 6 Oz and 2 layers of 9 Oz. This is what connects the firewall to the wing saddle.






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Old 02-22-2012, 02:21 AM
  #159  
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Changed the lamination a little - 3/4 Oz all over, 2 Oz all over, 6 Oz Chin Plate
Also layed in some scrap 1/8" ply to attach cowl mounting blocks to later.





...next to join main halves and then assemble with firewall subassembly
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Old 02-22-2012, 09:47 PM
  #160  
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Trimmed the perimeter with a blade at around 10hrs into room temp cure.
Prepped for joining with 80 grit paper.
Notice that I'm also going to insert the 1/8" ply dowel bulkhead now as well. I cut away the opening by removing the lower wing saddle sections of the mould and getting in there with a dremmel and a cutoff wheel rather than messing with the knife.






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Old 02-23-2012, 09:44 PM
  #161  
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Main Fuselage Joining

1" wide 6 Oz X2 layers
(gotta get some tape...)






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Old 02-24-2012, 06:41 AM
  #162  
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I can't believe I forgot to take a picture, but you'll have to take my word for it that there's a 1/8th ply bulkhead in there too. It's sandwiched between 3/4 Oz and several layers of 6 Oz cloth.

I impregnated the epoxy with black tempra with the idea being easy contrast witht any contaminates that might get picked up by the wing locating face...and I hadn't used black yet either


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Old 02-25-2012, 03:36 AM
  #163  
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now I'm havin' f-u-n heaven, I'm in heaven





ply insert is excessively strong...very nice for rigidity
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Old 02-25-2012, 03:13 PM
  #164  
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nice build thread
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Old 02-25-2012, 08:14 PM
  #165  
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All ready to join firewall subassembly to main fuselage assembly.
Although this resin and hardener combination is taking up to 48hrs at 72 F to cure to a point where I would consider demoulding it, I'm in no rush, and it seems to be extremely stiff in the wing saddle cross section when it finally does harden right out to the surface.








I am considering turning this cavity into an integral fuel tank....
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Old 02-26-2012, 08:09 AM
  #166  
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3 layers 9 Oz Cloth - 1" wide strips



This will eventually become the inside of the fuel tank.

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Old 02-28-2012, 03:33 AM
  #167  
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Oh boy, so much to tell....
This new cheap epoxy is great. It produces a stiffer, stronger part.
Now don't let the ugly test fuselage scare you off, here's some things we learned...

- surface veil for camouflage works great!
- some black sharpie around the perimeter of dark brown camo patches adds a level of detail too
- it is possible to match camo across parting lines
- tempra powder works great and is inexpensive (10% by resin weight)
- 1/4" ply is too heavy for firewall
- 1/8" ply dowel bulkhead works great
- assembly method for inserting chin plate / firewall subassembly works great! (I've been waiting to see if this would work for a very long time now)
- pink P-40's are for girls next time green/blown blend will be substituted for the lighter brown

I've also started on the firewall for the next one.
It will now be 1/8" Ply laminated with aluminum skin.
This aluminum looks to be around 0.020" maybe 0.5mm - it used to be a window awning...
I've also calculated that I can squeeze in around 16 Oz of fuel in an integral tank behind the firewall and centered around the plug in the pictures.

All in all, I'm already started on the next one...














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Old 02-29-2012, 01:32 AM
  #168  
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...not a lot of free time today, but here's a pic to motivate some of you to get away from the PC and wander back in the direction of your own workbenches....



how do like my computer skills!?
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Old 02-29-2012, 05:44 PM
  #169  
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We need some internals and they need to be inexpensive, lightwight, and easy to install.
I submit exhibit "A" - Aluminum with basswood if you please...11 grams worth






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Old 02-29-2012, 11:23 PM
  #170  
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Firstly - we've exceeded our bandwidth allowance for the original photobucket account, so all picture links from here forward will point to a new account that can be found here... http://s1069.photobucket.com/albums/u475/Two_Bulldog/


This is the rear cockpit bulkhead. It provides a vertical mounting surface on the rear face for our rudder and elevator servo mounting brackets. It also provides a shear pocket in the forward face, into which the hardwood blocks that draw the fuselage to the wing saddle will seat.

Please remember that these are prototype parts and although they're not necessarily the prettiest, they are functional and more importantly have provided templates, and benchmarks for all future part revisions.

Making more is easy work...









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Old 03-04-2012, 02:30 PM
  #171  
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If refinement is a fool's recipe for success, then I think on the right path...

worn out old uniform pants - could I get any more ironic?? )








Post Script - the missing pics will be back 031012
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Old 03-04-2012, 08:14 PM
  #172  
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So our templates for cutting cloth are getting more and more refined, and in addition we now have a complete set including not only the brown areas but also the green. This will allow me to accurately pre-cut and lay down the continuous strand surface veil everywhere as an initial layer. This is what keeps the epoxy concentration and therefore opacity high at the part surface.

Alright, you may have noticed that I keep chopping things up into smaller and smaller operations. This is because I'm only one person. I will focus on producing one section at a time and joining them post-cure. There's been no issues with the strength of any seam thus far and this will allow me to take my time.

so first it's brown camouflage portside on cssv



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Old 03-05-2012, 02:27 AM
  #173  
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Well, there's another 8hrs....I love this! Cosmetically this part should be ABSOLUTELY STUNNING!! :P


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Old 03-05-2012, 05:53 AM
  #174  
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This is 6 Oz tape. You don't want to know how cheap I get this stuff surplus.
One man's trash....

Talk about saving time!





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Old 03-05-2012, 06:07 PM
  #175  
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OK time to do a 'splainin' - what am I doing!?

There are a few things going on here at once but I'll do my best to take some time and explain my approach. I could lay down 2 layers of 6 Oz cloth, peel ply, blotter, bag it, and be done with it. Does that sound like me?? HECK NO!!

No, I want to capture that late 20th century, industrially manufactured, moulded-in, toy-like, monotonal opaque plastic look that people are drawn to and they don't know why.

The other thing I'm trying to do is make an airframe with a factor of safety of 1.1 - what's that mean? - that means just strong enough and that's it.

The main intent here is to saddle the firewall to the wing. In the following photos you can see where I've added 2 layers of a heavy 9 Oz cloth where the firewall and also the wing mounting blocks at the rear of the cockpit will be installed. Essentially they are 4" wide composite integral bulkheads. They are directly connected again by 9 Oz cloth through the chin plate in the firewall subassembly and also 2 layers of heavy cloth in the aft portion of the wing saddle.

Another concern are tail loads. Pitch loads are handled pretty well by the inherent "egg" cross section of the rear fuselage, but this capacity will be greatly enhanced when the port and starboard subassemblies are joined using 1" stips of 9 Oz cloth.
Yaw loading is transferred down the sides of the fuselage wall through and into the reinforced wing saddle by the 6 Oz tape that I've also overlapped along the centerline to form an integral longeron for additional beam strength.

If you look closely you will notice that there are areas where the fuselage will be only the thickness of the saturated cssv that forms the camouflage surface. Will this be enough?? Honestly, I don't know. That's why I tried it in a couple of small areas that are supported peripherally. I can say this much - I expect it to be as puncture resistant and as strong in tension as any iron on film.

I've also improved the flow through the integral exhaust manifolds.












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