SM2/RIM 67 HP build

[CCR]

I have wanted to build a HP 2 stage for awhile now and finally got started on it. I liked the looks of SM2/RIM 67 even though it is a bit more challenging than usual with the funky sustainer fins and strakes as well as the tapered and beveled booster fins.

I thought I would share the trials and tribulations of the build with the community as much of the information for the build came from people here or RP. I think the drawing I used for dimensions came from a VARocketry link and some techniques are inspired or copied from other posters.

Hoping to at least have it done for LDRS XXX at least but would like to get in a shake down flight that is kind of a “punt” shot to around 4k or maybe as a boosted dart to prove the separation stability prior to that. Planning to use a Raven in the sustainer for DD, separation and sustainer ignition duties. A MAWD will probably be used for booster deployment. The tubes will be glassed cardboard, 5.5” for the booster and 4” for the sustainer. Plywood fins will be glassed as well. 54mm mounts in both stages.

The markings are from Stickershock. Heck, I asked Mark to make up the markings over a year ago and he did a great job! I hope they have a good shelf life! Everyone sings the praises of Mark’s work but it isn’t the quality of his work that makes doing business with him a pleasure. This man is the most service oriented vendor, in or out of the hobby, that I have ever dealt with. We exchanged something like 16 emails discussing what I wanted. I don’t think he made much on a per hour basis on that job and I do appreciate him putting up with me and all the changes I asked for.

 

[CCR]

I wanted to machine the taper and bevels using a router. This kinda worked but I will have to modify my original plans.

Blanks for the booster fins were cut from 3/8 ply on the table saw.

The taper from root to tip was cut using a fixture with a sloping top and a hole for the router. When cutting the hole in the top, I used some old carpet tape to hold down boards to guide the router. The two oops in the top were caused because the tape didn’t hold. These divots caused some gouges later when I let the router follow the divot and the other side was no longer supported. The board on the low end is to stop the router from going to the end of the blank. I needed the full thickness of the blank at each end for cutting the bevels.

I planned to use carpet tape to hold the blank in the fixture but switched to masking tape due to the problem above.

I set the router to start the cut at the root leaving a flat tang for TTW mounting. Moving the router back and forth on the slanted surface cuts the taper. I had to reposition twice then flip the fin over and cut the other side. Oh, and sorry for the pic quality. My “good” camera is MIA.

Fins are all tapered. Yes there are five in the photo. I needed one to practice on!

 

[CCR]

I made a jig with a 6.5 deg vertical taper using two boards cut with a bevel and glued together. This angle ws choosen to try to give the proper bevel width. It is steeper than the normal Nike modified diamond but this is not intended to be true to scale.

Carpet tape was applied to hold the fin in place. NEW carpet tape!

The fin attached making sure the edges at the root and tip are flush to the bottom of the jig.

The fin is pushed up to an about 2” long ½” dia. router bit. Light cuts were taken to try to avoid tear out until the fin is against the board used as a kind of fence. The board also has a 6.5 deg bevel and a notch for the bit.

Four fins tapered and beveled.

 

[powderburner]

You really really want to put a scale bevel on those fins, don't ya?

NICE job! I am now very interested to see if you continue this high level of quality through the rest of your buid!

 

[CCR]

LOL

Well I don't have the quality thing down on these fins. The tapers were a bit rough. The edge where the bevel meets the flat part of the fin wanders due to inconsistent thickness and the tips are a tiny bit thinner than I planned. Could have been the masking tape, the jig or my technique but they are going to need more work. Going to need some 1/32" plywood and the use of some Superfil to fix this.

 

[CCR]

I am going to add 1/32 plywood doublers that are cut to match the flat areas between the beveled edges to each side of the fins. Going to try to use my HandiVac freezer bags for a vacuum press. The bevels will then have a layer of Superfil added.



This should give a crisper line than I had and since there won't be any outside fillets, the doubler should cover the edge of the cut in the body tube.

Based on my experience with the booster fins, I am not going to taper the sustainer fins. I am thinking I will use a 1/16 G10 planform covered with ply wood the same way as the booster fins and make the bevels using Superfil. Thinking the fibergalss will need to be reniforced since it will be the tang for mounting and again no exterior fillets.

 

[CCR]

The fins were trimed from the blanks using a scroll saw and then the plywood doublers were attached using 30 minute epoxy and the HandiVac to hold them tight while the epoxy cured.



Superfil was spread with a putty knife to reform the bevels. The transition from the flat to the bevel looks much, much better now. Only one side was done so far. This stuff takes awhile to cure. They will need some sanding and probably some auto body filler before glassing.

 

[CCR]

OK, back to work after doing taxes, yard work, rocket launch, etc. but not much progress.

Finished putting on the Superfil and sanded it down then applied a skim coat of Bondo spot putty and sanded it as well.

Here are better shots of the taper and bevel in the fins.

I need to get some basswood and cut pieces to form the thicker part on inboard trailing edge of the fins. Not sure if the fins should be glassed before attaching those pieces. It is a minor detail and if it doesn’t look good I will probably leave those off.

Next up, starting on the sustainer fins. I am now thinking that three layers of 1/16” G10 and a layer of 1/32” ply on each side will be used. One layer of glass would be cut to the planform. The next layer of glass and the ply will be cut to the shape of flat area between the bevels and epoxied together. I am going to try to then bevel the joined pieces from root to tip and use Superfil again to form the bevels to the edge. After the trouble with the booster fins I ain’t sure this is a good idea but to quote Kevin Bacon, “I got me a plan”. The tang will wind up being 3/16” thick layered glass. A much better idea than the original plan that would only have left 1/16”. The plywood will stop at the root. Thin plywood or card stock will be used to add detail to the fin root and I will try to shape a dowel to form the pivot mechanism.

 

[sodmeister]

Plenty of work no doubt ,but those fins turned out looking great ,a detail you really just can`t get around.

I look forward to this build ,it`s going to be great !

Paul T

 

[jimzcatz]

Just saw this thread. The AGM-78 Standard Arm is a favorite of mine. Currently working on a full scale(12" anyway). Is the SM-2 just a designation for the AGM-78 when used as a sustainer? I also have a 2stage in the works, 9.25 booster and 7.5" sustainer.

 

[CCR]

Jim, AFAIK, The AGM 78 and the SM2, RIM 66 (single stage) are very similar. The only external differences I see is that the AGM 78 has a slight taper to the tail like the Tartar and has the surface mount patch antennae on the forward part of the body. I hope to see pics of yours or better yet bring them to LDRS XXX. That 12" will be what, 13+ feet long?!!

For those that don't know, the AGM 78 is an aircraft launched ARM for use against ground radar. The RIM 67 (RIM = Surface Ship, Intercept-Aerial, Guided Missile) is a boosted version of the single stage RIM 66, both ship launched. The two stage RIM 67 is probably more accurately called an SM-2 ER (extended range) as opposed to an SM-2. While the 66 and 67 are AA or missile intercept weapons, I did read that the 67 was used to sink a vessel in practice but that was only one reference. The designations are confusing (SM, SM-2, SM-2 ER, RIM, A, B, C etc.)and pictures are often mislabeled on the net so take everything I say with a big chunk of salt! It took me forever to find out what the RIM stood for.

Paul and Powderburner, Thank you for the compliments. It is encouraging!

And Paul, if you were about 1000 miles closer I would be bugging you to help detail this thing. You are the Master!

Craig Rutherford

 

[Rocketman248]

....The RIM 67 (RIM = rocket, intercept, mobile)...

Close, but not quite. Surface Ship, Intercept-Aerial, Guided Missile.

https://en.wikipedia.org/wiki/Missile_designation

 

[CCR]

Yup, I stand corrected. That's what I get for believing what I saw on the internet! LOL

 

[sodmeister]

CCR ,I`m not a master ,just an observer ,which is why I follow your build.I am always learning new stuff here at TRF ,so I sit back and watch.....plenty to see and better than watching TV.

I like the way you tackled the fins, beauty ! I`m in the middle of a build myself....and the darn thing keeps throwning me left punches, but like yourself ,I try (and sometimes do ) find solutions.I love a challenge as do you, no doubt.

Carry on !

Paul T

 

[CCR]

Last night the G10 was cut into blanks for the fins and strakes. I taped a print from Rocksim of the sustainer fin to one of the blanks and cut a test fin. The cuts were made on the table saw using a relatively inexpensive 200 tooth plywood blade from Black and Decker. Not wanting to dull a good blade, I tried a masonry blade first but it wouldn’t cut. The B&D blade cut like a champ but later it smoked badly when cutting some ¾ ply.

This morning I stacked the fin blanks using double sided tape and scribed some lines on the face of the stack using the test fin as a guide. I made some minor adjustments to the original fin that I thought looked more to scale then cut the four fins at the same time. The notch at the base was started on the table saw then finished on a scroll saw.

The clampy thing on the miter gauge was something I purchased recently and never tried before. Wasn’t worth the cost.

I taped another template to a blank for the flat on the fin and cut the test piece. It looks about right and isn’t the blue fiberglass pretty!

 

[stickershock23]

beautiful job on the fins!

Can't wait to see it done!!

 

[CCR]

Thanks Mark! I can't wait either, I have been waiting but it never seemed to get done!

 

[CCR]

I wanted to taper the fins from root to tip by putting a taper on the flats on the fin. I had seen this disk sander blade at Sears and thought I’d give it a try.


My first thought was to do this vertically with a jig against the rip fence and tilting the blade. That won’t work. The blade extends about 3 ½ inches above the table top but I needed around 4 ½ in. Then I tried the sliding miter table. This was a royal pain. The jig was off a bit but I cleaned it up by using the sanding disk. I never could get the angle and distance to the blade correct. I thought I had it right, twice, but after four tries I gave up. It also would require multiple set ups taking a small bit off everytime. If you get a ridge at the edge of the balde, it won't cut anymore. An abrasive blade woul have been a better choice but still problematic me thinks. The router won't work either unless I get a bit longer than 2 1/4 in. Unless I think of something else to try before I get another chance to work on the rocket, the sustainer fins will have no taper.

 

[jimzcatz]

FWIW...A carbide tipped blade for a tablesaw cut 4,1/4 in fins taped together. Thats 1 inch and it cut like butter,no wear on the blade!!

 

[CCR]

Plan C to taper the sustainer fins is showing promise! It was raining when I got home tonight so I couldn’t mow the yard and I had time to take another look at the taper problem. After pondering the sander disk problem I decided to try a saw blade. I checked the saw for play in the miter table and didn’t find any. Found some melamine scraps and glued together another jig that was flatter, smoother and probably more square than the original. Put the plywood blade in and made a test cut. Had to shim the jig a hair and it appeared that the blade was deflecting at the top. Made another cut on a new piece with a feed rate of < 1/8”/sec. to reduce the deflection and it looked acceptable.


I was able to shave only about 0.050 in. given the stock was about 70 thou to begin with. It doesn’t add up to a very dramatic effect but I came this far so I will cut the rest of the pieces then trim those to shape and add 1/32 ply to the top.

 

[CCR]

I've been thinking about how to fab the strakes. In my ongoing effort to overcomplicate this build, I want to include a detail to simulate what appears to be mounting hardware at the base of the strake.

The strake will be 1/16" fg and the base piece will probably be 1/2" plywood with a groove to accept the strake and slots to allow parts of the strake to key into the BT for alignment. The plywood pieces will be narrow and about 2 feet long.

Does anyone have any thoughts on how to form the inside curve on this piece to match the BT?



I am contemplating making a short 4" dia sanding drum out of plywood. Sanding a bevel into the drum along the axis and mounting it on the table saw. I could then use a fence mounted parallel to the axis of the drum to guide the piece but looking for an easier/faster/better way to do this.

 

[gdiscenza]

Does anyone have any thoughts on how to form the inside curve on this piece to match the BT?

Cut your strake as normal but with a flat bottom. Wrap a piece of 80 or 100 grit sandpaper around the BT, and sand out the conforming curve from the bottom of the strake. Since you're using the actual BT as your sanding form, it should fit perfectly, assuming that your sanding strokes are straight along the long axis of the strake.

G.D.

 

[CCR]

assuming that your sanding strokes are straight along the long axis of the strake.

G.D.

Gregg, thanks for the reply. Your caveat is what worries me. The pieces are 2 feet long so getting an even cut and a straight one would be challenging for me anyway. Your idea would be easy to implement though and that's a plus. I may give it a shot with a 1x2 clamped to the tube along the axis.

 

[CCR]

Had to backtrack on cutting the taper on the fiberglass that forms the flats on the sustainer fins. Somehow by the time I got back to work on the project, the jig was moved and I had a hard time getting everything lined back up. While messing with this I had a “DOH!” moment. I switched back to the sanding disk on the table saw and set the miter gauge to the correct angle. By using the disk the way it was supposed to be used, by pushing the work into the face instead of from the edge like a saw blade, I had much better success. I had to eyeball the tip thickness but it worked out well.

I cut the FG pieces and some 1/32 plywood to the shape of flats, washed the FG then sanded and wiped with acetone and glued the FG and plywood together.


I washed, sanded and wiped the fins with acetone the glued the doublers on.


Superfil was applied like the booster fins but I taped the plywood edge this time and that helped keep things clean.


Another layer of filler will need to be applied. I may be using too much pressure. The filler surface always comes out concave. Note that the filler forming the front bevel at the root is crooked. That's not a problem though, this area will be covered by another part.

 

[cdondanville]

Gregg, thanks for the reply. Your caveat is what worries me. The pieces are 2 feet long so getting an even cut and a straight one would be challenging for me anyway. Your idea would be easy to implement though and that's a plus. I may give it a shot with a 1x2 clamped to the tube along the axis.

You could use two pieces of angle stock taped to the tube. Leave the width of the fin between them and they would act as a perfect guide along the axis and hold the sandpaper in place...

 

[CCR]

A little progress on the sustainer fins. Finished filling the bevels and primed after masking off the area where the fin socket (?) will be. Cut out some poster board for that detail and glued it on. You can (barely) see what little taper I achieved but the bevels look ok.


Had a little set back Friday when I wanted to take two fins to work to double check the weight. Left them on the roof of the Bravada. Found them hours later and one was pretty dinged up from being run over. Getting old sucks!

 

[CCR]

I need some odd size rings and such so I took the last two evenings make an easily adjustable table to mount the router on. In the past, I've cut rings using holes saws, jig saws, scroll saws, a jasper jig and even drilled pivot holes in a FRP router table and while all those methods work they have some issue or another that I found tedious (besides making swiss cheese out of a router table).

Here's what I came up with. I still need to add a 1/8 and/or 1/4" drill rod to the sliding bar and then I'll give it a test drive.

 

[CCR]

The router table works pretty good. I need to engrave some permanent witness marks or glue on a tape measure next to the sliding bar but using a pencil mark allowed for easy adjustments and repeatable cuts. A quarter inch pivot seems to be much more stable than 1/8 inch. I am just using a drill bit for the pivot for now. This is a pic of all the rings and most of the tubes for the interstage coupler and the centering rings for the booster.

 

[CCR]

Here is a mock up of the interstage. There is a 3/8” ring in the bottom with a 4” hole for a tube through the center, a 1/8” ring at the top of the coupler below a ¾” ring to center the 4" tube at the top. The 4” tube is the same height as the couple tube and has a coupler that extends to the height of the cone section. The stiffy tube shown will be replaced with a FG or CF tube that will extend from the bottom of 4” coupler up to the front of the sustainer fins and will have the 3/8” ring glued to it below the base of the sustainer to simulate the latching mechanism. The composite tube will have slots cut in the top to clear the fins. A foam block is cut with a hole to fit over the coupler and will form the cone shape section.


I started gluing pieces together using epoxy and realized I had not installed the u-bolt for the recovery harness. That old age thing again! I pried out the lower ring causing minimal damage, cleaned off the epoxy, installed the u-bolt and tried to replace the ring before the epoxy set. I applied fresh epoxy to the ring but had to use a rubber mallet to (not so) gently coax the part into place. When this was set, the foam piece was glued to coupler and a surform and sandpaper were used to shape it.


Can you see it yet?

 

[sodmeister]

OH..I can see it .And i like it !!!

Great build.

Cheers

paul T