1/2 Scale ALCM Cruise Missile and other non-traditional airframes

[sambatterman]

I'm in very early stages of planning for building a 1/2 scale AGM-86A Boeing ALCM Cruise Missile. I'm starting this thread as I am super interested in non-traditional rocketry airframes that are most easily described by various missiles/rockets - namely drones and cruise missile structures.

Eighteen years ago, I finished getting my Level 2 and started working in this area. Kids and career got in the way (as they do) and I was never able to explore this interesting area of rocketry. At the time I was fixated on a JASSM, which has a very different airframe than anything we see in rocketry. Here are the two photos that really inspired me:



Here's a picture of an AGM-158 JASSM that I was building (you can see the level 2 7.5" Bullpup in the background ).


Obviously this never flew, but over the last few years I've renewed my interest in going down this road. I've decided that I am going to pursue a 1/2 scale AGM-86A ALCM Boeing Cruise Missile. According to Wikipedia (and actually viewing this both at the US Air Force Museum and Smithsonian), this missile is 14' long. So the model I would create would be in the neck of the woods of 7' long. Really a perfect size for level 2 type motors and a size that would be good for a technical test platform for our hobby.

There are going to be people that are going to be critical of this idea and will say "this can never be done in rocketry", but both Estes and Centuri solved this as very small models with plastic shells that fit around a standard body tube and sticking a bunch of clay in the nose cone to bring the CG up. Wings and fins that are in "unusual" places are common in rocketry today: Jayhawks, X-15, Bomarc - we've already been near this with many existing models. Rocket powered gliders with unusual characteristics commonly show up. I'm sure many of us never thought we would see things like Vector Control and Arduino controlled, finless models. So, yeah, this will happen.



The fuselage is obviously inspired strongly by stealth, but so many modern platforms keep these same ideas. Some are shown here (AGM-136 Tacit Rainbow on the left and the AGM-129 Advanced Stealth Cruise Missile on the right):



So what are your thoughts? I've never seen anyone go here in modelling or flight.

 

[Ez2cDave]

There are going to be people that are going to be critical of this idea and will say "this can never be done in rocketry", but both Estes and Centuri solved this as very small models with plastic shells that fit around a standard body tube and sticking a bunch of clay in the nose cone to bring the CG up. Wings and fins that are in "unusual" places are common in rocketry today: Jayhawks, X-15, Bomarc - we've already been near this with many existing models. Rocket powered gliders with unusual characteristics commonly show up. I'm sure many of us never thought we would see things like Vector Control and Arduino controlled, finless models. So, yeah, this will happen.

As long as the CG and CP are in the proper locations, there is adequate control of the aerodynamic flight control surfaces, the correct Angle of Attack is maintained, and sufficient thrust is available, there is no reason that this project could not work. Granted, it is very complex, but those obstacles can be overcome.

This ALCM is my favorite prototype . . .



Dave F.

 

[teepot]

I say go for it. I have a Tomahawk, a 500lb bomb, a Sagger ATGM, an RPG and a 60mm mortar round. How did you make the nose of the ALCM?

 

[sambatterman]

I say go for it. I have a Tomahawk, a 500lb bomb, a Sagger ATGM, an RPG and a 60mm mortar round. How did you make the nose of the ALCM?

I haven’t made the alcm yet, but, you’re right, the nose will easily be the most complicated part.

 

[BigMacDaddy]

Someone just shared a thread about a massive 3D printer -- this might be a project for that...

Could 3D print nose cone (no worries about weight there) as well as frame cross-section pieces that would be connected with stringers (probably some other material) and all skinned with something (fiberglass?).

 

[Sandy H.]

I'm in very early stages of planning for building a 1/2 scale AGM-86A Boeing ALCM Cruise Missile. I'm starting this thread as I am super interested in non-traditional rocketry airframes that are most easily described by various missiles/rockets - namely drones and cruise missile structures.

Eighteen years ago, I finished getting my Level 2 and started working in this area. Kids and career got in the way (as they do) and I was never able to explore this interesting area of rocketry. At the time I was fixated on a JASSM, which has a very different airframe than anything we see in rocketry. Here are the two photos that really inspired me:

View attachment 516815 View attachment 516816

Here's a picture of an AGM-158 JASSM that I was building (you can see the level 2 7.5" Bullpup in the background ).
View attachment 516813

Obviously this never flew, but over the last few years I've renewed my interest in going down this road. I've decided that I am going to pursue a 1/2 scale AGM-86A ALCM Boeing Cruise Missile. According to Wikipedia (and actually viewing this both at the US Air Force Museum and Smithsonian), this missile is 14' long. So the model I would create would be in the neck of the woods of 7' long. Really a perfect size for level 2 type motors and a size that would be good for a technical test platform for our hobby.

There are going to be people that are going to be critical of this idea and will say "this can never be done in rocketry", but both Estes and Centuri solved this as very small models with plastic shells that fit around a standard body tube and sticking a bunch of clay in the nose cone to bring the CG up. Wings and fins that are in "unusual" places are common in rocketry today: Jayhawks, X-15, Bomarc - we've already been near this with many existing models. Rocket powered gliders with unusual characteristics commonly show up. I'm sure many of us never thought we would see things like Vector Control and Arduino controlled, finless models. So, yeah, this will happen.

View attachment 516818

The fuselage is obviously inspired strongly by stealth, but so many modern platforms keep these same ideas. Some are shown here (AGM-136 Tacit Rainbow on the left and the AGM-129 Advanced Stealth Cruise Missile on the right):

View attachment 516821 View attachment 516822

So what are your thoughts? I've never seen anyone go here in modelling or flight.

I'm not at all against the idea, but it'll take a lot of work and will also draw a bit of negativity on the forum at times, I imagine. LPR Odd-rocs are a bit more accepted than HPR Odd-rocs, and even though this one is a real rocket, it will be a challenge like an Odd-roc in way, probably. If you convince the RSO with good data that it'll fly as planned, I look forward to the flight.

What happened to the rocket you show in your garage. It is beautiful and shows that you know how to build great looking stuff. I have no idea how it would fly, but I hope it is currently in your possession or was donated to someone (hobby shop, school etc.) who is displaying it, as it looks awesome. I wish I had the knowledge and patience to make something like that. I'm not completely dumb, but, man. . . I AM LAZY!!!

Look forward to how this evolves!

Sandy.

 

[sambatterman]

Someone just shared a thread about a massive 3D printer -- this might be a project for that...

Could 3D print nose cone (no worries about weight there) as well as frame cross-section pieces that would be connected with stringers (probably some other material) and all skinned with something (fiberglass?).

Great idea! Definitely using bulkhead-stringer construction and fiberglass skin

 

[burkefj]

It's perfectly feasible to get these to fly as far as shape it just depends on what kind of construction and motors you want to use to determine how heavy and how stiff things need to be. Here's a slightly under half scale version of the A model which I prefer in the test colors that I also think are really great, this is an RC glider version made with 6 mm and 3 mm depron foam sheet with formers and sheet along the sides and bottom and the engine intake was just a simple profile to reduce drag. CG for rocket glider boost is set right about where the big CG mark is. This was designed for F-26 SU and G25 Moon burner 29 mm reloads and with the motor it was around 30 Oz ready to fly. I built this about 10 years ago has flown many times it used just fully movable tail surfaces for roll and pitch.

Here are the maiden flights, you can see how nice it flies in glide.



And one on the G-25

 

[sambatterman]

It's perfectly feasible to get these to fly as far as shape it just depends on what kind of construction and motors you want to use to determine how heavy and how stiff things need to be. Here's a slightly under half scale version of the A model which I prefer in the test colors that I also think are really great, this is an RC glider version made with 6 mm and 3 mm depron foam sheet with formers and sheet along the sides and bottom and the engine intake was just a simple profile to reduce drag. CG for rocket glider boost is set right about where the big CG mark is. This was designed for F-26 SU and G25 Moon burner 29 mm reloads and with the motor it was around 30 Oz ready to fly. I built this about 10 years ago has flown many times it used just fully movable tail surfaces for roll and pitch.View attachment 517051

Here are the maiden flights, you can see how nice it flies in glide.



And one on the G-25

Frank - thanks for your post. You are the person I was referring to about rocket gliders and indeed you are a legend when it comes to that area of rocketry. I'm especially interested in the Orion Clipper, modeled from 2001 a Space Odyssey, that you recently built (). It has similar features to the JASSM that I built 18 years ago - polygonal fuselage, under the fuselage wing - and perhaps most importantly a single fin (rudder, in your case). What is your opinion about what happens to CP when the fin count goes lower than 2? In OpenRocket, when you change from 3 to 2 fins, the CP jumps to the nose. Is this a math or heuristic issue? It seems like it is.

 

[Ez2cDave]

As long as the CG and CP are in the proper locations, there is adequate control of the aerodynamic flight control surfaces, the correct Angle of Attack is maintained, and sufficient thrust is available, there is no reason that this project could not work. Granted, it is very complex, but those obstacles can be overcome.

Dave F.

I think that your biggest obstacle will be gliding flight. Cruise missiles are designed to fly at high velocities . . . In slow, gliding flight, I think that the wing area will be insufficient and the rate of descent will be very high.

Glide recovery may not be feasible for this project. However, an alternative might be a "hybrid" recovery, consisting of RC-controlled "gliding flight" ( at high altitude ) and then deploying a parachute for "terminal" recovery.

Dave F.

 

[mikec]

I'm not at all against the idea, but it'll take a lot of work and will also draw a bit of negativity on the forum at times, I imagine. LPR Odd-rocs are a bit more accepted than HPR Odd-rocs...

IMHO any negativity is about unsafe flights of things that are just stupid stunts with a rocket motor (e.g., cars, snowmobiles, etc.) I think a real missile subject is always fair game for a flying model at any level. Go for it!

 

[burkefj]

Open rocket should handle a single fin fine. the problem that it has it is only shows you the worst case CP, either the top or side view, so if you're making changes to a vertical fin let's say to make it larger or smaller if the top view is limiting your CP you won't see any impact, sometimes I'll make two simulations one with a single fin and then duplicate that fin at 90° so I have two side views effectively and see how the fin changes impact CP and then do the top virw separately to do the same thing. I'm not sure why the CP would move to the nose with a single fin but you can hack the simulation just have the area of the fin and have two fins at the rear with half the area and it has the same impact. The main problem you're going to have I think once you get the CP figured out is the thrust line in asymmetric drag with a low wing and a single fin, I usually try to take a swag at having the thrust line close to the most draggy part of the model looking at the front view but since I'm controlling it I can trim out small differences and my motors have low thrust so the dragon pack is less than if you have a fast burning high thrust motor and then the arcing of the model will be larger if you have asymmetric drag. Sometimes I'll use around tube for the body and then make thin shapes that attach that simulate the polygonal side view area to get a better idea of how the CP is impacted.

Frank - thanks for your post. You are the person I was referring to about rocket gliders and indeed you are a legend when it comes to that area of rocketry. I'm especially interested in the Orion Clipper, modeled from 2001 a Space Odyssey, that you recently built (). It has similar features to the JASSM that I built 18 years ago - polygonal fuselage, under the fuselage wing - and perhaps most importantly a single fin (rudder, in your case). What is your opinion about what happens to CP when the fin count goes lower than 2? In OpenRocket, when you change from 3 to 2 fins, the CP jumps to the nose. Is this a math or heuristic issue? It seems like it is.

 

[sambatterman]

It's obvious that the most difficult part of this build will be the custom nosecone (duckbill), so I did some research on this very distinctive feature of the Boeing AGM 86-A ALCM. I read the book "The Evolution of the Cruise Missile" - which is pretty academic and dry but did have some rare photos of the cruise missile as well as some interesting history including why Boeing loses the cruise missile contract momentum to Northrup.

The nosecone has similarities with the fuselage in that it's faceted and polygonal, but the nose takes these features and smooths them out. The top and bottom of the nose cone are really quite different from each other. The tip of the nose cone is more a rounded plane - lots of blended surfaces here.

 

[KenECoyote]

Over in the 3D Printing forum here there's a thread where they're trying to make a copy of the Estes ALCM...may be very helpful for your project.

 

[sambatterman]

Re-vectoring the conversation to my new thread:
https://www.rocketryforum.com/threads/1-2-sport-scale-alcm-agm-86-a.174608/

Watch the design, construction project there.

 

[georgegassaway]

View attachment 516818

The fuselage is obviously inspired strongly by stealth, but so many modern platforms keep these same ideas. Some are shown here (AGM-136 Tacit Rainbow on the left and the AGM-129 Advanced Stealth Cruise Missile on the right):

Actually, the sloped sides of the fuselage were not for stealth, AFAIK, but could "Accidentally" have helped. They were designed to fit inside of the bomb bay of B-52's.

They were loaded onto a "rotary dispenser". To get the maximum use out of that space, a trapezpoidal cross-section was ideal. See pic.

This Google search link shows a lot of pics of the rotary dispenser.
https://www.google.com/search?q=b-5...SlcBa8Q_AUoAXoECAIQAw&biw=853&bih=397&dpr=1.5

 

[sambatterman]

Hi @georgegassaway, thanks for dropping me the comment. If you follow the link right above your comment, it will take you to the construction of this beast which is underway. Yep, the shape was largely for "cramming" these things together for rotary launch - but the ones in the picture above have more "refined" planforms than the AGM 86-A prototype. The book "Skunk Works" by Ben Rich talks about the defense labs applying the faceted approach used on the F-117 "hopeless diamond" to cruise missiles. Yeah, that was Lockheed, and the AGM 86-A is Boeing, but it's a small community - even when it's top secret. Hope you'll take a look at the construction thread.

 

[Hobie1dog]

wow, what a project you have. keep your pictures coming.