|Feb 25, 2012, 03:17 PM|
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....
|Feb 27, 2012, 10:36 PM|
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...
|Feb 28, 2012, 08:35 PM|
...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!?
|Feb 29, 2012, 12:47 PM|
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
|Feb 29, 2012, 06:27 PM|
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...
|Mar 04, 2012, 09:33 AM|
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
|Mar 04, 2012, 03:16 PM|
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
|Mar 05, 2012, 01:15 PM|
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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