2.6" ASP WAC Corporal Build

Made some serious progress today. I completed the motor mount and secured (epoxied) the piece of 750# Kevlar that will be serving as the shock coard mount. I also remember (thank the good Lord) to measure the location of the forward centering ring stack as this will serve as the mount for the forward rail button.



I then mixed a moderate size batch of BSI 30 min and secured the motor mount in the airframe (no pictures of this, but you can imagine what it looked like)

Next came the fins. It’s really getting exciting now! A test fit led to some final sanding to get everything just right. Then mix a small batch of T88, and “double butter” the root to ensure a good bond to the motor mount. Then, a good coat on the extra thick root edge that bonds to the airframe and tail cone.




Can’t ask for much more here.

As for all the bevel discussions, I opted to leave the trailing edge square. Sanding showed that the balsa was VERY fragile where it tapered gradually to 0 and the thought of repeatedly landing on this sort of edge didn’t excite me. Even with a coat of laminating epoxy (which I will do once the fillets are complete). I toyed with the idea of a smaller bevel, but the lack of symmetry would have driven me NUTS.

As for the fillets, I am thinking of using T88 to pull some very small fillets. I like the look of big round fillet transitions, but I don’t think those will “fit” this build. Given the contact area of a 3/8” wide root and some small fillets, this should be plenty strong, though I do invite thoughts here. So what do you think? Would a small tounge depresser fillet be sufficient?

Second coat of epoxy is fully cured. I’m going to knock down the point a little during final sanding then hit it with some primer to see what I’ve reall got.



The second fin is on. Used the same method as the first one.

Looking good. Makes me think that I should get my Semroc Wac out and just build it....

YES! Build away my friend!!!!

Lots of work going into the conduit. I underestimated how hard it would be to shape / remove the required amount of material



I used 220 wrapped around the airframe to shape the underside, then 100 to “knock down” the major parts and 220 to shape. This is after a solid hour of work. Yea, I could have prolly used a mechanized tool, but I don’t want to remove too much or cause some crazy splinter that would need to be filled

Fin #3.

Looks fantastic Sean! I absolutely have to get one of those now.

from looking at your back end, me thinks you are going to have a bit of a struggle with adding a retainer..

But the build overall does look awesome!

That is the ‘mother’ 38mm. I will be permanently installing the 29mm adapter with retainer

I stand corrected!

thank you!

Hmm, a coat of laminating to fill and smooth the nose cone may just help shift the cg forward for unwise motors!

Looks like this is coming together very nicely! I have the 29mm Wac Corporal and my brain keeps telling me to get the 38mm. But then my pocketbook interrupts and does an Amy Winehouse and says
No!
No!
NO!

Nytrunner said:

Hmm, a coat of laminating to fill and smooth the nose cone may just help shift the cg forward for unwise motors!

Click to expand...

Hey, Nyt. See post #22. Theory is one step ahead of all of us.

Thanks for the kind words all. The detail work of finishing the nose cone and getting the conduit just right is proving to be a challenge.

I did complete the fillets today. Went with 30min BSI and the tounge depresser. Worked well. Next up there is a coat of laminating epoxy one the fins and tail cone. Not sure when I will get to that :-/

Thanks for this thread! Nice build! I just started building the same kit, the insights on some things like the dowel for rail button mounting is much appreciated, as are the other building tips. I was considering gluing in the 29mm permanently (plenty of power), but I opted for the 38mm Aeropack retainer with the 29-38 adapter. I will use the 29's first and can always go the 38's later. Will have to be careful with the CG, but the adapter doesn't weigh that much.

work is moving forward. on to priming / sanding / priming / sanding the nose cone.

one interesting thing about the nose cone is that it is designed to fit into a coupler, then the coupler fits into the airframe. similar to FWFG cones. what is interesting here is the coupler supplied is 6" long. this strikes me as unnecessary for a 2.5" diameter airframe. any qualms / concerns with cutting it down to a more reasonable 4"? the reduction in length will educe friction and make it easier to work with.

thoughts?

Theory said:

work is moving forward. on to priming / sanding / priming / sanding the nose cone.

one interesting thing about the nose cone is that it is designed to fit into a coupler, then the coupler fits into the airframe. similar to FWFG cones. what is interesting here is the coupler supplied is 6" long. this strikes me as unnecessary for a 2.5" diameter airframe. any qualms / concerns with cutting it down to a more reasonable 4"? the reduction in length will educe friction and make it easier to work with.

thoughts?

Click to expand...

I used the ASP cone in my BT80 WAC Corporal (not the kit, just the cone), I used a coupler just a little longer than the shoulder, because that's what I had on hand.

The coupler -- while it makes the airframe more resistant to zippering -- makes a constriction/internal edge at the top of the airframe. Last time it flew, I had this disappointment...



...when the JLCR hung up on the edge of the coupler. A longer coupler might have made this less likely, but then so would having done a better job of packing the parachute.

ya know, I like the idea of adhering the coupler to the airframe and then using the nose cone in the more traditional fashion. I would likely want to coat the balsa with something to make it more resilient, but that is easy enough to do.

good idea!

Theory said:

ya know, I like the idea of adhering the coupler to the airframe and then using the nose cone in the more traditional fashion. I would likely want to coat the balsa with something to make it more resilient, but that is easy enough to do.

good idea!

Click to expand...

Do the instructions call for adhering the coupler to the NC to make up the ID of the airframe? Okay, now I am embarrassed. Since I didn't build the kit, I just assumed that the reduced shoulder on the NC was for zipper-proofing.

edit: FWIW, the nosecone I got was kind of a loose fit in the coupler I found in my parts pile. I have to put a wrap of Tamiya tape on the shoulder to pass the shake-test.

yes, they call for using the coupler as a part of the nose cone, and not making it a part of the airframe, hence the supplied bulk plate and hardware. my guess is that combination of components is more resilient in the long run.

your idea is a sound one though. I need to measure the shoulder of the balsa cone to ensure there is enough area for a sound fit

I hollowed out the nose cone a little and made a tracker bay. Tight slip fit on the nose cone, added weight inside. Kept the 38mm mmt and it flew great on higher impulse H motors.

Warmed up the garage and took care of the fins and tail cone with a good coat of laminating epoxy.

The nose cone is coming along, bout 85% of the way there. Two more prime / sand cycles and we should be ready for paint.

I have decided to adhere it to coupler per the instructions, however, I will shorten the coupler to 4”. That is plenty of ‘shoulder’ for a 2.5” airframe

B

Got the nose cone looking really good. Shot it with 4 coats of satin black. Boy it looked good!

Why I said looked...

#fail

Beautiful build. I also have a 2.6 ASP WAC. This build thread will help a lot.

Many years ago, I shot some video of the one on display at the Smithsonian. Perhaps it might be helpful:

helpful indeed! you and I have studied the same artifact (see avatar)

thank you my friend.

Got the conduit sanded the wood way I wanted (finally) and glued it on. There’s about a 1/16” gap all the way along each side. Not sure what I am going to fill that with, but I am thinking that I will try out that “super thick” tite bond