10" lightweight Atlas Missile

Franks now got me headed in the direction of a scale Mercury Atlas, maybe using a Estes NC or maybe not.

Created the little rounded portions of the front of the skirt piece from scrap BT-70, and then covered the whole thing.. here it is in place on the tube skeleton, I have since shortened the front tunnel since it was sized for the mercury atlas version but the missile tunnel on the D model is much shorter.

The tunnel pieces, skirts, nozzles and the warhead were the parts that kept me from starting this for a long time, now that figured out how to make them work, I have confidence I can get it done.

Weight for the skirt and tunnel assembly covered is 1.75 oz.

Glad we could help each other....

rharshberger said:

Franks now got me headed in the direction of a scale Mercury Atlas, maybe using a Estes NC or maybe not.

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Yes, that was a neat project....Dick stafford did something similar to me a while ago with foamboard and cardboard skins in a Redstone and V-2'ish, I started doing this type of construction for my Titan DynaSoar stack to keep the weight low enough to use an H-97 and keep boost speed low enough I wouldn't shred the lightweight glider...using just depron structure and skin since that's what I had on hand, then I just kept going with it.

I'm not a master at complex shapes/curves like some of the other RC folks, so I have to choose subjects that don't have large fins sticking down and fairly simple shapes...Hellfire and Pershing for example or just chose to live with standoff scale. It's good for models that have small fins and normally need a lot of nose weight because the structure seems to come out more nose heavy than normal construction...It's also sort of fun to fly things at this larger scale with fairly small inexpensive motors.

JohnCoker said:

Very cool. I like it when people try something unusual.

We used foam to build the 19' N1 (Russian Moon rocket) in 2001:
www.moonrace2001.org/n1_rocket.shtml

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Stand-off scale works for me

Thanks Peter.....

PeterAlway said:

The middle photo, with the red tail section is sort of a bastardized display model-- It may be an Atlas A with a sustainer engine thrown in, or it's an Atlas B, with a warhead of a later model that didn't fly on either type. Only A and and some B models had the pointed tunnels of matching length.

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Was talking to Dave Davis who organized Narcon this year, and he was encouraging me to reconsider clear fins....So I ran out to tap plastics and got some 1/16" makrolon(lexan) polycarbonate and cut some out. I put some lightening holes in the fin root and got them down to 2.5 oz each, heavier than i want but might be ok. I made them triangular thinking this would be the least likely to flutter. I slit the centering rings so that the fin slides in and I don't have to build a fin box. The cool thing is the fin angle made me think of putting some yellow trim monokote on the top edge and it will simulate the vernier flame....I think it will look pretty good in the air. This may push the weight beyond the H-180 and mean I have to fly on I-205 or I-200's...we'll see.

I did get the stuffer tube and coupler today so I don't have any parts I'm waiting on, so I should be able to get the airframe pretty far along, skin it and it will start to look like something resembling an atlas....My 2mm skin is actually about .5 to 1mm thicker than the real thing, dave was saying I should fill it with helium....

Joined the stuffer tube, and put the centering rings on with eye bolt, everything layed out for assembly in the morning.

Frank

Clear fins--I like!

Cool! The clear fins were probably the right thing to do.

A bit more progress this morning, everything layed out for assembly. They way I approach this is do to the front first, install and glue the transition skeleton to the parachute bay/stuffer tube, then roll on the skin. After that I can slide on the rear structure and roll the skin on that. It's much easier to make little tweaks to the skin on the joint on the straight portion as opposed to the top portion, the top portion I can roll on with extra sticking over the end and then trim it. I also show the stuffer tube centering rings, I've put the eye bolt through both since this is what takes all of the recovery load, and I wanted it tied to the stuffer tube in two places. Then I slid on the parachute bay and glued that in place. I also show the little cap with a hole in it, this is what the wires passing through the stuffer tube pass and connect to the deployment charge, this cap then fits into the stuffer tube and seals it and the wiring off from the ejection charge. I dry assembled it, starting to look like something, I find I have to do this every so often, it makes me feel like I'm making progress....

Frank

Looking good Franks, at this rate it will be ready to fly next weekend....

Looking Good!!!

What's next? A Saturn V?

I finished the upper transition longerons, and installed them, then sprayed the whole thing with 3m-77 spray and wrapped on the skin, actually went pretty smooth...

Added the wood supports that the rail guides will attach to. Then slid on the lower structure and made sure I had marks for where the fin slots were, the rail guide supports were aligned, the rail guides were not interfering with the fins/lower skirt(yes it was so I had to rotate the structure.....) Taking a break, then I'll glue all the lower structure joints once I'm sure it's all straight, then skin it. then the fun of putting on the mylar will start..I'm thinking I'll have to do the transition vertically, since the foam skin isn't perfectly round(it flattens slightly between the longerons) I don't think doing curved wraps will work well...and doing curved wraps is very material wasteful using 6" wide strips like I can get.

Frank

Got the skin on...that was a bit of a struggle, I thought my sheets were large enough to do it in one piece, but I forgot to do a quick pi*D and was 1/2" short, ugh...so I had to trim and tape two pieces together and apply it, had just a small gap at the seam at the top I was able to fill, and it will be covered by the mylar covering in any case. Here she is....Weighs 53 oz right now.

Frank

Lookin' good!

burkefj said:

Might be ready to fly, but I probably won't, I usually need a month or two of staring at the model before I get over the emotional attachment and won't be heartbroken if it crashes...Saturn V, don't know...still thinking about a minuteman or 12" little joe II..
......

Frank

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The Atlas is looking fantastic.

Speaking of Little Joe IIs, a model aircraft and rocket buddy of mine and I have been discussing a team effort on a 1/10 scale Little Joe II (about 15.4" in dia and about 103" long) using the Depron approach.

Cool, if you do it then I won't have to At that scale, if you keep it light, you could maybe fit the recovery gear into the escape tower tube

Due to the large fins, I thought of having mine come down horizontally, maybe with side ejection or something...

tab28682 said:

The Atlas is looking fantastic.

Speaking of Little Joe IIs, a model aircraft and rocket buddy of mine and I have been discussing a team effort on a 1/10 scale Little Joe II (about 15.4" in dia and about 103" long) using the Depron approach.

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Started the silver covering..Worked ok so far, just start with a straight band and then follow each one and don't let them get crooked. I'm out of the chrome now but I have to wait till I figure out the side pod locations before I can do more anyway. the mylar strips are 5" wide so I'm doing 2.5" bands which is close to scale based on what I'm seeing in pictures, I have no dimensions for the bands...

Frank

OMG, that is looking AWESOME!

burkefj said:

Cool, if you do it then I won't have to At that scale, if you keep it light, you could maybe fit the recovery gear into the escape tower tube

Due to the large fins, I thought of having mine come down horizontally, maybe with side ejection or something...

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There is that method that Estes uses for the Mercury Redstone/Atlas nosecone. In this case you'd attach a line to the front and back of the rocket, and reinforce the joint to prevent zippers.

I think this is all I can do today, ran out of chrome, need two more sheets but pilfered the two hobby shops near me of all they had already.Re-slotted for the fins and they look like they are straight still. I'm still trying to figure out what sort of glue I'm going to use on them Foam safe CA seems like it is sticking, or jb, problem is the joint is so thin it's hard to get much in there, or maybe go with something flexible....Weight with two fins installed is 64 oz. I decided to pony up for rocksim and see if that gives me any better CP location to avoid as much nose weight. I also need to re-cover the side skirt, when I slotted it for the fin the covering wrinkled...I probably should have covered it after attaching it anyway...

Frank

Nice touch with the simulated vernier thruster flame on the fin.

I did a test and it looks like the makrolon/lexan fins are gluing to the foam and tube well, had anyone had a bad experience with foam safe ca and lexan? Any foam safe alternatives?

burkefj said:

I did a test and it looks like the makrolon/lexan fins are gluing to the foam and tube well, had anyone had a bad experience with foam safe ca and lexan? Any foam safe alternatives?

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I have used Lexan a number of times in the past and although they were each odd-rocs and foam-filled, I never relied on the two-part foam for adhesion. I always did TTW construction with generous amounts of Plastic Epoxy along the root and root fillets.



Oh, my bad, you were referring to the foam board construction with CA--can't answer that; I don't use CA for any adhesive applications, generally poor bond qualities all around. I only use CA to seal edges of tubing and drill holes.

Polyurethane glue....as long as the glued surface is hidden.

I did some testing and found some JB plastic weld epoxy for the root edge and foam safe CA+ for the foam to fin bond, I pulled the test pieces to destruction and the joint didn't fail. So, all fins are installed. I pulled the covering off of the one engine bell shroud I made and mounted that and will cover it again. I also cut and made the electroncs bay with door and magnet latch. The wires go from the altimeter pod up through the stuffer tube and into the parachute bay, the deployment charge wires will go through the little cap, and attach to the large wires and will slip into the end of the stuffer tube to seal it all up. Currently at 78 oz, missiing the chute, altimeter, motor and a the other skirt piece...

I tried some pink CA+ ruberized which stuck really well to the fins, but melted the test piece of foam.

Frank

Awesome! Your pace is impressive as well.

Fins are all installed and I re-covered the motor skirt once glued in place, it was much easier. Now just to build the other side conduit/skirt and wait for my chrome to come in.

Frank

LOOKS FABULOUS!

Thanks all for the encouragement! I got my rocksim download and did a sim using rocksim, and using rocksim stability calculation it pushed the CP back another 5" so is 22.25 from the base of the rocket, right now my CG is right at 32.25, we'll see if I have to add any balast, if I do, I can put it right at the base of the balsa cone, so as far forward as possible.

The fins are pretty flexible, if I lay it down, the fins just bend so that the body touches the floor, which may be a good thing, when it lands, it should put less strain on the actual glue joint I hope, we'll see. Max velocity is between 130 and 150 mph, hopefully flutter won't be an issue for this slow and short a flight.

Frank