1/2 Sport Scale ALCM AGM 86-A

alexzogh

Well-Known Member
TRF Supporter
Joined
Sep 30, 2010
Messages
958
Reaction score
599
Location
Northern Virginia
I was surprised there aren't more comments here - great build so far. I was wondering if you thought about putting on the exterior panels first, then filling in the void with foam instead of all of the shaping and sanding (and tiny pieces of foam everywhere!). Maybe the balsa wouldn't be able to withstand the expansion pressure?

Also wondering what the air intake is going to do to the flight characteristics.
 

sambatterman

Well-Known Member
TRF Supporter
Joined
Feb 9, 2022
Messages
186
Reaction score
258
I was surprised there aren't more comments here - great build so far. I was wondering if you thought about putting on the exterior panels first, then filling in the void with foam instead of all of the shaping and sanding (and tiny pieces of foam everywhere!). Maybe the balsa wouldn't be able to withstand the expansion pressure?

Also wondering what the air intake is going to do to the flight characteristics.
Hi Alex - thanks for your note. I have tried the balsa panels first and then the foam - if you get too much, then the foam will warp or bulge the balsa and you lose the planar look I'm going for. The fiberglass on top of the panels resolves the sturdiness of the skin.

The reason I'm building this (beside that fact that it's a cool rocket) is that no one in the hobby really knows what this kind of airframe will do in the air. Other examples of things that are similar are the X-15, Bomarc, etc. These are generally symmetrical though - the ALCM and most other modern missiles - especially air-launched are not symmetrical. This will definitely be interesting to fly. My suspicion is it will be "draggy" and "bend" the trajectory towards the airscoop as it ascends.

I was looking at your site - great looking rockets and lots of technique. Thanks for sharing this resource!
 
Last edited:

sambatterman

Well-Known Member
TRF Supporter
Joined
Feb 9, 2022
Messages
186
Reaction score
258
A slow, but productive day

I feel like I didn't get much done today, but the airframe sure is looking like a cruise missile. The belly is now sanded and covered with Carbon Fiber. I have some work to do on the transition to the mid-fuselage, but overall, it looks pretty good. I dug all the Styrofoam out of the intake and I'm preparing to seal that shut in the next week.

627A704B-9A12-458A-9B5C-413CD4A42695.jpeg

I bought some foam board to work out the size and angle of the wings. These wings will attach to the wing plate that sits under the transition bridge, but before the mid-fuselage. There will be an option for wings on and wings off. This foam board wing is about what the size will be. You might notice the "sharpie" marks on the fuselage - these are cosmetic areas that need smoothing or filling and I'm working on that this weekend. I find that JB Weld works best for this kind of thing.

6EDE54EE-76E0-4C88-BE88-E671DC27B7BD.jpeg

And for what can only be described as a "cheat:" This is the core nosecone that will couple to the mid-fuselage. A super structure will be hung on the outside to get that distinctive "duck-bill" shape that the ALCM is famous for. You can see the bulkhead that will line up the nose with the mid-fuselage, dry fitted here. That's the last "easy" bulkhead I get on this rocket - everything from here out will be very difficult, I'm afraid.

You might look at these lengths and think, "that nosecone is too long." I thought the exact same. The reality is that together, this length is perfectly 1/2 scale. The whole thing currently weighs around 25 pounds.

57ECAAE5-A140-4939-A850-612B4F99023F.jpeg
 

Attachments

  • 40A2A548-7ED0-47FB-A812-3C98232F5C8A.jpeg
    40A2A548-7ED0-47FB-A812-3C98232F5C8A.jpeg
    1.7 MB · Views: 0
Last edited:

jd2cylman

Still not Carl... ;-)
TRF Supporter
Joined
Jun 16, 2011
Messages
5,968
Reaction score
1,938
It's too bad you couldn't duct the air through the scoop and out around the motor mount... extra work, but would be cool. Plus, could be interesting to see what it did to the motor exhaust plume.
 

Rocket86

Well-Known Member
Joined
Apr 26, 2010
Messages
942
Reaction score
128
Location
WA
Daunting, and very cool. I just found this and will be following now. Very impressive so far!
 

sambatterman

Well-Known Member
TRF Supporter
Joined
Feb 9, 2022
Messages
186
Reaction score
258
Nosecone Superstructure

The nosecone interior superstructure is basically done. It's a complicated thing and will support the unique "duck-bill" look of the ALCM.

The entire front edge of the nosecone is rounded and flat on the top and bottom, making for a complex blending project.

R (5).jpg

I chopped off the front 4" of the nosecone, to give the front edge a nice strong "pedestal" on which to rest.
The top and bottom transitions are unique in where they are - and it took me a while to figure that out. There is fiberglass tape reinforcing the plywood bulkheads.

Next up - foam, shaping and balsa panels. Followed by fiber glassing - at least two layers.

73EA83DF-6B3B-49F7-B083-BB8AB80EDF29.jpeg
 

sambatterman

Well-Known Member
TRF Supporter
Joined
Feb 9, 2022
Messages
186
Reaction score
258
The Nominees for Ugliest Nosecone are in…

Got a lot done this weekend and wanted to share. I foamed the nosecone superstructure (see post above). It took two full cans of small cell foam. When you use this much foam you need to let it set for many hours or you'll cut into a semi-cured foam blob and it's sticky and gross.

659E1A42-CDF0-4DCC-A29B-0EA430F6F263.jpeg

After the first carving period and some sanding with a disc sander - looks like something from Jurassic Park...

45F601C3-E23C-4721-8E73-7B614923B106.jpeg

Getting there - still sanding and cutting - it will be a while before I start putting balsa panels down. I'm thinking the nose will be finished by putting down SuperFill - many more sandings and then at least 2-3 layers of fiber glass.

32B28DC4-7FEC-45F9-A67F-D4CA7FC721CD.jpeg

Oh yeah, my wings came in the mail this week - I needed something very strong and stiff. I wanted to go with 3/16" carbon fiber, but it was way too expensive - something like $500. So.... I chose purple heart, which is strong and stiff and has a nice finish right off the planer. The wings are 1/4" thick and will attach to a wing panel just behind the mid-fuselage with bolts. As I mentioned at the beginning of this whole thread, I'm going to have an option for wings on and wings off. They are very "draggy" - and if the Openrocket simulation is to be believed, we lose at least 450 feet with the wings on. Still, that's part of the experiment for this type of rocket.
EF58BE79-3C67-4A57-A5BA-500C7531BF4E.jpeg
 
Last edited:

burkefj

Well-Known Member
Joined
Jan 27, 2009
Messages
4,033
Reaction score
2,027
Yes, number 2 is the only way to go for this model!
 

sambatterman

Well-Known Member
TRF Supporter
Joined
Feb 9, 2022
Messages
186
Reaction score
258
Initial fit of wings and wing plate

Here's a quick look at the wing plate and the pop out wings for the cruise missile. As I mentioned elsewhere, there will be two wing plates - one with wings and one without. The wings change the predicted altitude significantly, but I want to see how they change the dynamics of flight as well. I used threaded inserts and furniture bolts to make it easy to remove and attach at the field.

F1737C6D-FC37-434A-B97E-CBD35D0687C2.jpeg 9D41CC07-CCD9-4458-9CCE-6DB91E8E77C0.jpeg
 

sambatterman

Well-Known Member
TRF Supporter
Joined
Feb 9, 2022
Messages
186
Reaction score
258
Getting the Wing Plate Integrated

So, I'm bouncing between working on the ALCM and doing some work on my shuttle stack project. Here's the wing plate attached and being integrated into the aft fuselage. Lots of blending to do at the bottom. The wings are attached to a plywood/carbon fiber sandwich with 8 furniture bolts. The wings themselves are purple heart - extremely strong and light. They attach to a carbon fiber/plywood sandwich that is secured with two brackets and many screws. Getting there.

1A73389F-7AB6-4C69-AF8D-AC4860F5BE8B.jpeg
 
Last edited:

sambatterman

Well-Known Member
TRF Supporter
Joined
Feb 9, 2022
Messages
186
Reaction score
258
Working on the avionics hatch

The mid fuselage around the avionics hatch is now "balsa'd" and fiber glassed. I 3D printed the hatch and lined the edges with very small styrene strips to reinforce the edges. It looks pretty sharp. It will be bolted down with 8/32 hex bolts and 8/32 t-nuts. Some more sanding to do - seems that's all I ever do on this thing. Tomorrow I will be 3D printing the fairing that covers the pop out wings and carving on the nose cone again. It's coming along.

7A5B4778-B828-4168-8A72-475A81E86CFB.jpeg
 

Attachments

  • 7A5B4778-B828-4168-8A72-475A81E86CFB.jpeg
    7A5B4778-B828-4168-8A72-475A81E86CFB.jpeg
    2.1 MB · Views: 2
Last edited:

sambatterman

Well-Known Member
TRF Supporter
Joined
Feb 9, 2022
Messages
186
Reaction score
258
Revisiting OpenRocket for the ALCM

When I started the project, I needed some general length and weight information, so I plotted the basics of this rocket into OR. Now that I have some better measurements and weight, I decided to revisit the design and get some updated numbers.

The fins, wings, nosecone and body tube are all updated with some simulated weight on the bulkheads. With electronics, drogue, main parachute and an L-2200, it sims at 3300 feet. Minimal nose weight - around 8 pounds. This is very similar in profile to my Nike Hercules. I expect a lower altitude from the wings and the general drag of the airframe (especially the air scoop area).

1672345584600.png
 

sambatterman

Well-Known Member
TRF Supporter
Joined
Feb 9, 2022
Messages
186
Reaction score
258
Custom Nosecone for ALCM

It’s been a minute, but I’m back to working on the ALCM. Specifically the Nosecone which is half balsa panel and half foam.

7D9012FE-B202-4FD3-8C6E-F5917B701816.jpeg

8BDCA407-EAF8-4F9C-BF6C-47C5F96BB892.jpeg

C59C2D1D-A23E-443C-958C-7FA37C6E42BF.jpeg

I put SuperFill all over the structure and smoothed it out, filling holes and valleys. I'll be sanding that off this week and will share the results. Once the surface is great, I will be covering it with 2 layers of fiberglass. Then it's time to prime and sand the whole thing down before paint and decals. I can see light at the end of the tunnel. It may fly at Red Glare 2023 MDRA or NY Power - if we can get some warm, nice weather this spring.
 

dbpeirce

Well-Known Member
TRF Supporter
Joined
Jun 17, 2018
Messages
289
Reaction score
302
Awesome! Wait till I tell my brother that you used purpleheart for the wings!! It may just be the thing to get him back in the hobby!!!
He always incorporates it in to the guitars and basses he builds.
 

dbpeirce

Well-Known Member
TRF Supporter
Joined
Jun 17, 2018
Messages
289
Reaction score
302
Here’s one
 

Attachments

  • BCD10587-314C-41D0-8561-591A96416E0C.jpeg
    BCD10587-314C-41D0-8561-591A96416E0C.jpeg
    2.3 MB · Views: 0
  • 707B6D8E-460C-42ED-AA29-6A76FDB7079A.jpeg
    707B6D8E-460C-42ED-AA29-6A76FDB7079A.jpeg
    2.1 MB · Views: 0
  • AC6773E0-B8B1-4674-81F3-F6AB23296EFE.jpeg
    AC6773E0-B8B1-4674-81F3-F6AB23296EFE.jpeg
    2.2 MB · Views: 0
Top