Hi,

I've started building the vintage FSI Star Gazer (or is it Stargazer?) kit I received from barone a while back, and have a couple questions for you FSI experts.

The kit came with optional 18mm motor mounts, which I'm using. These 18mm tubes are 3", while the booster BT is 2.75". The root edge of the booster fins is 3". I also noticed the shape of the booster fins don't exactly match the scans on this site - mine are 4 sided, missing the short cut from the root to the trailing edge. They look just like the drawing on the first page of these plans. If I made this cut, they would fit fine on the booster tube. So, are the fins wrong, or is the size of the booster tube wrong? Looking at the drawing on the instructions, I'm tempted to say the booster tube is too short.

Second question is decals - this kit doesn't have any decals, and the decals scanned here don't match the drawing in the instructions. Did the decals come in later kits?

Thanks!

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Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

I built my Stargazer clone with a 2.75" length of Semroc ST-8F (equivalent to FSI's RT-8) for the booster. My booster stage is the same length as the booster fin root. The reason that you have 3" long 18mm adapter tubes is because when you glue one of them into the booster, the extra 0.25" extends out of the top and acts as a coupler, fitting over the exposed end of the sustainer motor. With the booster motor installed flush into its stage, and the stage fitted over the exposed end of the sustainer motor, the two motors will be butted up against each other, just like they should be. In practice, you would tape the two motors together, insert the pair into the sustainer and then fit the booster stage over the dangling motor. You'll have a little bit of extra length in the 18mm motor mount above the sustainer motor, but that's OK.

Remember that the Stargazer was designed to use FSI's 21mm diameter motors, and the tubes were (more or less) minimum diameter. The taped motors actually acted as the coupler between the stages. When you adapt the Stargazer for 18mm motors, the extra length of 18mm tubing is meant to provide that coupling, because those motors are smaller than the ID of the tube. But you might want to obtain an HTC-8F coupler from Semroc and glue that in as well to provide more support for the joint between the stages. That's what I did.

I used the fin patterns shown in the plans at YORP to make the fins for my Stargazer, and they fit perfectly. I am not sure what the discrepancy is that you are finding. I wouldn't rely on the drawing on the front page of the plans to be an exact scale representation of the finished model. This has always been common practice; the line drawings accompanying most rocket plans from most companies (past and present) are not necessarily exact representations of the actual rocket, nor are they meant to be. Based on my experience, the fin templates in the online plans are quite accurate; you can trust them.

You can get reproductions of decals for the Stargazer from Excelsior Rocketry. Although they are not on my model yet, I have a set of them, and they are beautiful.

MarkII

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SAM # 0011

I forgot to mention that the decor of the Stargazer evolved over the nearly 30 years that it was produced. The 1971 catalog drawing of it (which is depicted on the first page of the plans at YORP) was neither the first nor was it the last paint pattern for it. The design of the decals changed over the years as well. (Again, this is hardly unheard of in model rocketry.) You can view some of MRK-II's iterations by viewing the various FSI catalogs at the Ninfinger model rocketry site.

I'm not sure what to tell you about the long root of your kit's booster fins. I do have the impression (not sure where I got it) that in some versions of the SG, there was a small but definite gap between the leading edge of the booster fins and the trailing edge of the sustainer fins. In later versions, that gap was eliminated so that the fins fit together, as they do in my clone. I'm just speculating here, but perhaps in your version, FSI had already decided to eliminate the gap, but was doing it by making the booster fin taller (with a longer fin root) instead of adjusting the placement of the two sets of fins. Again, this is just speculation, but in your version, perhaps the root of the booster fin was meant to extend up past the joint between the two stages, and then nest in under the sustainer's fins. Why they would do it that way at that point in the SG's evolution may have had something to do with reluctance to move the placement of the sustainer's fins for some reason.

The designs of most of FSI's oldest kits (Penetrator, Stargazer, etc.) morphed in great and subtle ways over the years that they were produced.

MarkII

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SAM # 0011

Paul,

The early version of the Stargazer didn't come with decals. I can't remember which version you got from me but it sounds like you got the early version. MarkIIs comments seem to fit your situation. You may notice from earlier posts concerning FSI kits, the QC was somewhat skimpy. If your kit included the 18mm conversion, that particular kit was propably in transition from earlier kits that didn't feature the conversion parts and probably didn't have all the kinks worked out. The kit I built was a later issue carrying the 1000 series kit number. There is no gap between the booster and sustainer fins.

The instructions you link to state that the booster tubes are 2.75" long so the tubes shouldn't be the issue. And the instructions don't show the fins extending over the end of the sustainer as noted by MarkII. In your situation, I think I would go ahead and build it with the material supplied, adjusting the placement of the sustainer fins to accomodate the overlap from the booster fins.

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Don
NAR 53455
"Carpe Diem"

I've attached a scan of the booster & sustainer fins. Note the different shape between my booster fins and the plans here. The root of the booster measures 3".

Which catalog drawing do the excelsior decals represent? Thanks.

Thanks, I hadn't thought to look there. My fins match those depicted in the 1967 & 1970 catalogs; in fact, these catalog drawings show a 3" booster tube size (76mm).

. This makes sense - that might explain the earlier non-clipped, 3" fins, but newer, 2.75" booster tube. It has the MRK-II part number designation on the bag. I'm inclined to get a semroc tube and build the booster to resemble the 67 & 70 catalog dimensions.

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Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

Paul, great timing! I have a Star Gazer hanging on the hooks that will be on the build table as soon as I get cleaned up from Midwest Power.

Do you intend to bring the Star Gazer to the March Sod launch? I'm intending to be there with my FSI fleet:

Eos: FSI D20-3
Penetrator (Semroc): FSI E5-4
Star Gazer: FSI D18-0 to D18-6
Mach 1 Dart: FSI F100-0 to D20-7

... and then the Semroc Hydra with 5 or 7 "renegade" C5-3's.

If you wish to fly your SG on authentic FSI motors, let me know; same offer as the Firefly from last year. I'm looking forward to that launch!!!

-Eric-

Thanks Eric, that's a generous offer. I'm planning on building her with the 18mm mounts, so will have to pass this time. I *do* hope to be at that launch, it'll be great to see those FSI flights, especially the 2-stagers! I'll be sure to bring my Star Gazer. I've been flying the C5-3 motors on my X-Wing - perfect motor for that bird. Be prepared for, uh, early ejection if you use more than 3 of these in a Hydra VII, unless you put them in plugged tubes, and use a longer delay in the open tube(s).

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Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

Eric, do you have a stash of old FSI motors? Those FSI E's were just great! If I recall correctly they had about a 4 second burn time! Very cool!

Joe

I don't know that I'd consider it a stash, but I do have several FSI engines in the collection. I love motors/engines that are unique from what is available today ie big black powder motors, slow/fast burn bp, etc.

I only make it to one or two WOOSH launches a year, and try to fly unique items with them there. When I saw the March theme, I put that launch on my "must attend" list.

Back to the thread; Paul can't wait to see photos of the build! Bummer you're gluing in one of those motor choice limiting mount devices . Re: the Hydra, Yessir, the C5-3 tubes will be plugged; therefore it will definitely be less than (7) C5-3's....thanks for the reminder.

-Eric-

I have a few rockets configured for the FSI 21mm engines, including a couple of two stagers. When I get around to flying, I always like to do at least one of those, especially a D20-0/E5-6.