# FSI Intrepid

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#### JAL3

##### Well-Known Member
A bout 2 years ago, I bought an FSI Intrepid kit on Ebay. It was supposed to be complete. I finally opened it up today and found that everything seems to be in good shape but that there are no instructions or decals. I looked on Jimz and didn't find anything.

Does anyone have scans?

#### JAL3

##### Well-Known Member
Got it!

THanks!

BTW, The Swift BG is defying all expectation and looking like it will be a success. Gliders and I do not get along but this one has been sweet all along.

Great kit.!

#### MarkII

##### Well-Known Member
Yeah, but can you scratch-build one?

I'm about to start building my 18th FSI clone, which, fittingly, will be the Maverick, MRK-XVIII. I'll probably save the Intrepid, who was FSI's last kit, for my grand finale. To date, I have flown 11 of them, and they have all turned in spectacular flights. Hey, I've even painted 5 of them! I did have one mishap with my Hercules, when it crashed badly (into the trunk of a very large tree) in its second flight after lifting off on two out of the three D12's in its cluster, and suffered severe damage. I will be building a second Hercules with a single engine mount in addition to trying to repair my first one. I have never owned an FSI kit, but eventually I will have all 30 of their models cloned.

Did your Intrepid kit come with a decal?

MarkII

#### JAL3

##### Well-Known Member
Did your Intrepid kit come with a decal?

MarkII
Nope. But the link Carl gave me has the decal and I can print it up.

Since I couldn't get this one started I got started on something else and this one dropped a space back in the line.

#### JAL3

##### Well-Known Member
I've just been taking a look at the instructions for this beast. It seems that FSI's motors were 27mm and that Es and Fs were recommended. I am trying to decide whether to build it as a 24mm mount or a 29. My inclination is to go with 24 but would appreciate any advice.

#### rockets2000

##### Well-Known Member
Build it with both! 29mm adapter/mount and 24mm friction fit mount. That way you can fly it on just about anything.

#### MarkII

##### Well-Known Member
John,

If the FSI model in question used a 27mm mount, I always build my clones with 29mm mounts. The 9" long RT-10 that is used for the central motor tube in the Intrepid is identical in size to Semroc ST-11, but its inner diameter is one tick too small for 29mm motors to fit. (My 29/40-120 RMS motor will go into ST-11, but no 29mm SU motors will do so. The tubing is a bit thin-walled for use with 29mm motors, anyway.) If you are building the kit stock, then you will need to create a 24mm adapter for it. (Easy to do with parts from Semroc.) If or when Quest ever releases those 28mm diameter black powder E's and F's that they announced last year, they will fit in that motor tube. Those Quest motors could in some ways be the reincarnation of FSI's mid-power motors; at least they will fill the same niche in the market. If you want to fly your Intrepid on 29mm motors, you will need to substitute an equivalent length of 29mm motor tube (such as Semroc LT-115). Semroc makes centering rings that will center LT-115 into the Intrepid's RT-17 airframe (which is equivalent to Semroc ST-18). I have yet to actually fly any of my 29mm-equipped FSI clones on a 29mm motor yet, though. (I haven't built up enough courage for that yet. ) It's a simple task to make a 29mm to 24mm adapter using Semroc components.

For 21mm FSI mounts, I install a standard 18mm mount. I don't know of any plans in the works for creating new motors in 21mm diameter. Quest's 20mm D5 would fit, but it only comes in a plugged version, and I don't know of any plans by Quest to release a version of it that has a delay and an ejection charge. The Quest D5's could be used in the Intrepid's outboards, but the motor has such low thrust that I don't know if using a pair of them would be worth it.

One other tip -- The instructions for most FSI kits with 27mm motor mounts call for gluing a thrust block into the motor tube. I never do that. The thrust blocks were meant for FSI's motors, and the spacing listed in the instructions were only for them. Since you won't be using FSI motors (I don't think), I wouldn't bother with installing the thrust block.

I have never laid eyes on an actual FSI kit; all that I know about them comes from the plans at YORP, the catalogs at Ninfinger, and some occasional posts on the forums from people who had built them. So I'm really interested in reading your build thread for this kit. I'm sure that it will fill in some of the gaps in my knowledge as well as answering a few questions.

One thing that I'm curious about is if the RT-8 tubes used for the outboards on the Intrepid really do have an inner diameter of 0.903". FSI catalogs list this tubing as having an ID of 0.903" and an OD of 0.921". I have questioned those dimensions, because they would result in a wall thickness of 0.009", which would be much thinner than any other paper tubing ever used in a production kit from any manufacturer in model rocket history. It would be about half the thickness of standard spiral-wound kraft paper tubing in that approximate diameter, and would be equivalent to a single wrap of index cardstock. An ID of 0.903" is approx. 22.94mm. Semroc's version of this tubing, ST-8F, has an ID of 0.885" which yields a much more believable 0.018" wall thickness. It's inner diameter is equivalent to about 22.47mm. RT-8 was the tubing that FSI used for its 21mm motor tubes, but those motors obviously did not have anything like a close fit in those tubes. FSI always recommended wrapping the motor with plenty of tape to achieve a firm friction fit. (FSI kits never used motor hooks.) If anyone ever produces 22.5mm diameter motors, then these would make great motor tubes. I'm not asking you to go and mic the tubes, but if you happen to have any ST-8F on hand, would you be kind enough to compare the diameters of Semroc tubing and the FSI tubing? (Eyeballing them and feeling for any difference would be good enough.) Thanks in advance.

MarkII

#### Carl

##### Well-Known Member
I'm not asking you to go and mic the tubes, but if you happen to have any ST-8F on hand, would you be kind enough to compare the diameters of Semroc tubing and the FSI tubing? (Eyeballing them and feeling for any difference would be good enough.) Thanks in advance.

MarkII
I took the measurements for the ST-8F from several FSI tubes I had. One was from the Louisville address (Penetrator about 1967) and another was from a 1990 kit (Competitor.) They were very close in size. FSI catalog dimensions did not match the actual dimensions on that one tube. The other tube sizes were much closer.

#### JAL3

##### Well-Known Member
John,

If the FSI model in question used a 27mm mount, I always build my clones with 29mm mounts. The 9" long RT-10 that is used for the central motor tube in the Intrepid is identical in size to Semroc ST-11, but its inner diameter is one tick too small for 29mm motors to fit. (My 29/40-120 RMS motor will go into ST-11, but no 29mm SU motors will do so. The tubing is a bit thin-walled for use with 29mm motors, anyway.) If you are building the kit stock, then you will need to create a 24mm adapter for it. (Easy to do with parts from Semroc.) If or when Quest ever releases those 28mm diameter black powder E's and F's that they announced last year, they will fit in that motor tube. Those Quest motors could in some ways be the reincarnation of FSI's mid-power motors; at least they will fill the same niche in the market. If you want to fly your Intrepid on 29mm motors, you will need to substitute an equivalent length of 29mm motor tube (such as Semroc LT-115). Semroc makes centering rings that will center LT-115 into the Intrepid's RT-17 airframe (which is equivalent to Semroc ST-18). I have yet to actually fly any of my 29mm-equipped FSI clones on a 29mm motor yet, though. (I haven't built up enough courage for that yet. ) It's a simple task to make a 29mm to 24mm adapter using Semroc components.

For 21mm FSI mounts, I install a standard 18mm mount. I don't know of any plans in the works for creating new motors in 21mm diameter. Quest's 20mm D5 would fit, but it only comes in a plugged version, and I don't know of any plans by Quest to release a version of it that has a delay and an ejection charge. The Quest D5's could be used in the Intrepid's outboards, but the motor has such low thrust that I don't know if using a pair of them would be worth it.

One other tip -- The instructions for most FSI kits with 27mm motor mounts call for gluing a thrust block into the motor tube. I never do that. The thrust blocks were meant for FSI's motors, and the spacing listed in the instructions were only for them. Since you won't be using FSI motors (I don't think), I wouldn't bother with installing the thrust block.

I have never laid eyes on an actual FSI kit; all that I know about them comes from the plans at YORP, the catalogs at Ninfinger, and some occasional posts on the forums from people who had built them. So I'm really interested in reading your build thread for this kit. I'm sure that it will fill in some of the gaps in my knowledge as well as answering a few questions.

One thing that I'm curious about is if the RT-8 tubes used for the outboards on the Intrepid really do have an inner diameter of 0.903". FSI catalogs list this tubing as having an ID of 0.903" and an OD of 0.921". I have questioned those dimensions, because they would result in a wall thickness of 0.009", which would be much thinner than any other paper tubing ever used in a production kit from any manufacturer in model rocket history. It would be about half the thickness of standard spiral-wound kraft paper tubing in that approximate diameter, and would be equivalent to a single wrap of index cardstock. An ID of 0.903" is approx. 22.94mm. Semroc's version of this tubing, ST-8F, has an ID of 0.885" which yields a much more believable 0.018" wall thickness. It's inner diameter is equivalent to about 22.47mm. RT-8 was the tubing that FSI used for its 21mm motor tubes, but those motors obviously did not have anything like a close fit in those tubes. FSI always recommended wrapping the motor with plenty of tape to achieve a firm friction fit. (FSI kits never used motor hooks.) If anyone ever produces 22.5mm diameter motors, then these would make great motor tubes. I'm not asking you to go and mic the tubes, but if you happen to have any ST-8F on hand, would you be kind enough to compare the diameters of Semroc tubing and the FSI tubing? (Eyeballing them and feeling for any difference would be good enough.) Thanks in advance.

MarkII
It looks like Carl has gotten you the data on the FSI tubes. Its a good thing too. I was trying to decide which kind of microphone to put on the tube.

I think that I'll probably go with the 29mm mount. That gives some flexibility and the promise of the Quest motors is fairly alluring as well.

#### MarkII

##### Well-Known Member
I took the measurements for the ST-8F from several FSI tubes I had. One was from the Louisville address (Penetrator about 1967) and another was from a 1990 kit (Competitor.) They were very close in size. FSI catalog dimensions did not match the actual dimensions on that one tube. The other tube sizes were much closer.
Thanks, Carl; that's what I thought. FSI carried that incorrect and nearly impossible dimension in their catalogs for over 20 years and never fixed it.

MarkII

#### JAL3

##### Well-Known Member
I had 2 nice surprises waiting for me when I got home today.

Gordon of Roachworks/Excelsior sent me a reproduction of the Intrepid decal.

Carl and Sheryl from Semroc sent me the motor tube for a 29mm mount in this rocket AND a 24mm adapter.

Its been said in other places and at other times but let me repeat here that the people of the rocket community are some of the nicest there are. Thank you so much.:clap:

#### rockets2000

##### Well-Known Member
Carl and Sheryl from Semroc sent me the motor tube for a 29mm mount in this rocket AND a 24mm adapter.
Yessss!!!!

#### JAL3

##### Well-Known Member
WHen I began the build, I could not find my original thread so I stared a new one. I since found it and merged the two beginning with this post.

A few years ago, I bought a reputedly unopened Intrepid kit on Ebay. It was not unopened and a few things were missing including instruction, part of the motor mount and the decals. I posted about it at the time and was surprised when Carl at Semroc sent me a motor mount and Gordon from Excelsior sent me the decal. There kindness was most appreciated and unexpected and I was going to get started right away. Life intruded, though, and I really did not get a good start until today.

I not building this in the order of the instructions and I began by marking the halfway mark on the coupler.

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#### JAL3

##### Well-Known Member
Without thinking, I swabbed one end of a body tube with Titebond II and started to insert the coupler. I pushed too hard and it went in too far and the glue grabbed. I used pliers to pull it back as far as I could but it was not to the halfway mark.

#### JAL3

##### Well-Known Member
The other BT was swabbed with glue and the 2 parts were joined and set aside to dry.

#### sodmeister

##### Well-Known Member
I just did that last week.The thing is ,I usually use 5min. epoxy because of that exact reason ,but i got lazy and used the old FAST grabbing wood glue......and being a little "ham fisted" at times ,did what you just described.

Im back to epoxy when doing couplers ,especially those tight ones (TLP kits are bad for that ,very tight fit)

Paul

#### JAL3

##### Well-Known Member
I just did that last week.The thing is ,I usually use 5min. epoxy because of that exact reason ,but i got lazy and used the old FAST grabbing wood glue......and being a little "ham fisted" at times ,did what you just described.

Im back to epoxy when doing couplers ,especially those tight ones (TLP kits are bad for that ,very tight fit)

Paul
I actually avoid epoxy most of the time because I just don't like messing with it, emphasis on the mess. I only recently started using Titebond and am still getting used to how quick it grabs. I bought some TB III for just that reason and it still has not been used. I just plain forgot.

The coupler was actually a pretty smooth fit. The problem was me.

#### JAL3

##### Well-Known Member
The transition was in perfect shape and felt like it would hardly need any filling.

#### JAL3

##### Well-Known Member
I swabbed a ring of glue around one end of the payload tube and inserted the larger end of the transition.

#### JAL3

##### Well-Known Member
The nosecone too was a work of art but its fit in the payload tube was extremely loose. I debated gluing it in place since I have no interest in payloads but decided not to.

#### JAL3

##### Well-Known Member
Instead, I wrapped the base with masking tape. It took three complete turns and a little extra to get a snug fit.

#### JAL3

##### Well-Known Member
The cone was then placed in the payload bay and set aside.

#### JAL3

##### Well-Known Member
I decided to go with the 29mm motor mount which is a good thing since that is what Carl sent me. I don't know a lot about FSI but I think I understand that their motors in this size were really 28mm and their tubes reflected this. The Semroc tube I received was shorter that the FSI original but should be good enough for anything I will try. I did, however, have to do some sanding in the centering rings.

#### JAL3

##### Well-Known Member
I sanded the insides of the rings until all three fit snugly over the motor tube.

##### Well-Known Member
Mark is gonna be incredibly jelous....

#### UPscaler

##### New Member
Mark is gonna be incredibly jelous....
maybe not for long...

this is a cool build!

#### MarkII

##### Well-Known Member
More fascinated than jealous. A build thread of an actual FSI kit, and it's for no less than the mighty Intrepid! This is so cool!

FSI's F7 and F100 motors, and later their E60, were 27mm (1-1/16") in diameter. Their A4 through E5 motors were 21mm (about 53/64") in diameter. The smaller motors were about 17% larger in diameter than conventional 18mm motors, and the larger ones were about 13% larger in diameter than 24mm motors. All of their motors used black powder propellant. Their A4 through D6 motors were all 2.75" long, their D18, D20 and E5 motors were 3.75" long, the E60 was about 3-15/16" long (100mm), and the two F motors were 6" (150mm) long.

John, could I trouble you to give me the length (minus shoulder) of that nose cone?

#### MarkII

##### Well-Known Member
Gordon made you an Intrepid decal? He doesn't have it listed on Excelsior's web site, but of course that doesn't mean that he can't make one. I wonder if I could ask him for a couple of others that he doesn't list? Hmmm, I'll have to drop him a line.

I am enthusiastically following this thread.