FlisKits Cut-Away Motor Rocket Motor

FlisKits - Cut-Away Motor Rocket Motor {Kit}

Contributed by David Landgraf

Manufacturer: FlisKits
(Contributed - by David Landgraf - 01/02/09)

Brief:
If you have ever been at a loss for a giant version o' a model rocket motor t' use as a teachin' aid t' hold up in front o' a class, me hearties, this is your ticket. Avast, shiver me timbers, me proud beauty! This little kit provides a good illustration o' t' internal parts, gives you a model in a good, usable size, and is easy t' assemble in a couple hours o' total work time. Ya scallywag! Begad! It requires primarily a sharp X-Acto knife and some Elmer's-type white glue.

The inside of the finished motor model. The outside of the finished motor model. These are the kit parts labeled in Step 1 of the instructions.

Construction:
When I first opened t' kit, me bucko, me bucko, I be impressed with t' high quality o' t' laser-cut sheet, both t' material and the laser work. T' sheet material from which components were cut be a cardboard-type product that was very light while still havin' good strength and stiffness. Well, blow me down! Begad! T' faces o' t' sheet were finished with a "plastic" layer that made me think o' t' exterior o' Estes-style body tubes. Arrr! T' laser-cut lines were (to me) very narrow (0.1 t' 0.2 mm?) but were straight, arrr, arrr, neat, matey, and without any noticeable scorch marks on t' surroundin' material. Blimey! Parts were connected to the main sheet by tiny webs that were easily severed with t' tip o' a sharp X-Acto knife. Begad! Parts fit so snugly within the sheet that a little patience and care be needed t' separate them without damagin' t' edges o' t' parts.

Before separatin' any parts from t' laser-cut sheet, me hearties, shiver me timbers, it would be good for t' builder t' check and make a clear identification o' all parts before separatin' them. Begad! Arrr! Blimey! Builders should note that t' spine is slightly different from the two casin' caps (and may want t' pencil a label on t' parts t' note which is which). Avast! Similarly, matey, me bucko, t' four nozzle parts (the half-disc-shaped items down t' center o' t' sheet) should be noted and identified. It is nay difficult t' see a difference betwixt t' nozzle 1/nozzle 3 parts and t' others because 1 and 3 have a large center cutout (and if I am not mistaken, nozzle 1 and nozzle 3 are t' same size and interchangeable). Aye aye! T' most important difference is that nozzle 2 has a small center cutout and might be mistaken for nozzle 4 if t' builder gets in a hurry.

Builders can remove parts more easily by slicing the laser-cut sheet in one or two places around the selected part. For Step 2, me bucko, t' builder must remove t' spine, casin' caps, shiver me timbers, and ribs from the laser-cut sheet. These parts should be handled carefully as they are relatively delicate until they are assembled. Arrr! It is easy, ya bilge rat, me hearties, for example, t' bend t' long, arrr, thin, narrow spine and casin' caps, ya bilge rat, but they need t' be quite straight for this kit t' work. It might be a good idea for t' builder t' separate these parts by cuttin' t' connectin' sprues, me bucko, then place t' sheet on a flat cuttin' surface for support and cuttin' away t' surroundin' sheet material from one end. This makes it much easier t' remove these parts gently from t' rest o' t' sheet and keep them straight.

I found t' four parts needed for Step 2 and checked them for flatness and clean edges. Arrr! I used only a very small amount o' glue t' assemble each rib t' t' spine; a dot o' glue from t' tip o' a toothpick was enough t' prep each connectin' joint. Begad! Large amounts o' glue are really nay necessary at this point (or at any point in this kit) and would just make a mess. Aye aye! T' parts are pre-cut with tabs and slots, me hearties, and t' fit be very good. Avast!

The assembly instructions in Step 2 say to 'Take care to make sure that all 3 ribs are vertical.' I think I got it nailed. I had no difficulty completin' Step 2 but worked smartly (before t' glue dried completely) and checked for proper part alignment by placin' t' finished assembly upside down on a good flat surface. All six rib tips should sit squarely on t' flat surface. Ya scallywag! I also used a framin' square (two tablets o' paper could also form a 90 degree corner) and a plastic triangle t' check that t' end ribs were square and t' spine was straight. Blimey! I handled this thin' very carefully t' set it aside, and let it dry while workin' t' next steps.

In Step 3, arrr, me bucko, t' nozzle pieces and t' propellant plate are assembled. Avast, me proud beauty! Blimey! Again, I used t' tip o' a toothpick to apply glue t' t' joints, me bucko, me hearties, this time because I wanted t' be able t' adjust them a bit (if needed). I used me plastic triangle again t' check alignment, but t' corner o' a business card or any small object with a square corner could be used. Avast! Blimey! Aye aye! Blimey! It be easy t' clear t' waste material from t' pre-cut slots and I found t' pre-cut tabs fit cleanly and firmly into t' slots. Begad! Blimey! (Jim, have you given any thought t' completely cuttin' these slots, with no sprues, shiver me timbers, so t' tiny little pieces just fallout?) Once these parts are properly assembled, t' builder can add more glue but it really isn't needed.

The right nozzle parts (the half-discs) need to be in the correct locations, and need to be square with the propellant plate.The right nozzle parts (the half-discs) need to be in the correct locations, and need to be square with the propellant plate.

Providing good support for the Step 4 assembly and pressing it gently into alignment while the glue dries. For Step 4, me hearties, t' two casin' caps are added t' t' edges o' t' assembly from Step 2 (the delicate one). T' casin' caps appear t' be symmetrical and can be turned either way and will still fit properly. Begad! I used me trusty toothpick t' place a small dot o' glue on t' tips o' t' ribs and spread it across the joint. Blimey! Ya scallywag! I worked smartly t' complete this assembly and re-checked everythin' with me framin' square and plastic triangle, matey, tryin' t' keep everythin' square durin' and after handlin' these delicate parts. Finally, arrr, I placed the assembly upside down on a flat surface and laid a light object (the plastic triangle) across t' top t' gently hold all the parts in alignment while t' glue dried. Begad! Avast, me proud beauty! Let t' glue dry thoroughly; do nay proceed if this rib assembly is "soft" or loose.

In Step 5, t' BT-60 is finally glued t' t' inside o' t' rib assembly from Step 4. Avast! Blimey! Blimey! I think t' best way t' glue this whole thin' together is t' use only small amounts o' glue on t' inside o' t' rib framework for t' initial assembly t' t' BT-60. This way t' glue dries quickly, and if t' framework needs t' be repositioned, shiver me timbers, it will nay be as difficult t' cut through all t' glue joints. Aye aye! Arrr! Blimey! Once t' rib framework is in place, matey, the builder can add more glue t' all t' joints, but more glue should only be added t' t' "framework" side but should be kept clear o' t' opposite side t' make life easier in followin' steps.

Apply a thin fillet of glue for reinforcement along the ribs, spine, and this side of the casing caps where they attach to the BT-60.Do not apply glue on this side of the casing cap joints (or you will just have to cut through it in Step 11).

In Steps 6, matey, me bucko, 7 and 8, shiver me timbers, follow t' directions. Begad! Jim provides a normal wraparound markin' guide for t' outer BT-70 tube and did a good job o' describin' how t' mark and cut. Builders will end up with two sections o' BT-70 that are two slightly different widths...and they are supposed t' be that way. Begad! (In other words, don't second-guess the instructions and split t' BT-70 exactly in half. Ask me why I am makin' such a big deal out o' emphasizin' this.)

For Step 9, arrr, t' assembly from Step 5 will be glued into t' wider o' t' two pieces o' BT-70 from t' previous step. Avast! Aye aye! In order t' get a good glue bond in t' middle o' this thing, me bucko, I used an end rib as a markin' guide and made a pencil mark where t' center rib would touch t' inside o' t' BT-70 so I could apply glue while this area was still open. Note the Q-tip that was used t' spread out t' glue.

Split BT-70.
Marking where the center rib will fit, using the end of the assembly from Step 5 as a marking guide.Applying glue on the pencil line and on all the other places where the assembly from Step 5 will attach to the inside of the BT-70.

In Steps 10 and 11, matey, arrr, arrr, t' model motor case will really take shape. In Step 10, shiver me timbers, t' builder trims off t' excess BT-70 so t' edge o' that BT matches t' flat surface o' t' casin' cap. Blimey! (Remember how t' BT-70 is supposed t' be wider than half o' t' circumference?) Hold t' cuttin' edge o' t' X-Acto at a shallow angle and make several passes. Try really hard nay t' swerve over and cut into t' casin' cap because you will only be makin' that much more repair work for yourself. In fact, if you leave a little bit o' BT-70 after cuttin' with an X-Acto, me bucko, you can finish it off with an emery board.

Trimming off excess BT-70 using an X-Acto knife.Sand lightly with an emery board to bring down the remaining edge of the BT-70 even with the flat face of the casing cap. (Don’t worry if the casing cap gets a little scuffed up.)

Cut through the BT-60 even with the flat face of the casing cap. In Step 11, t' builder will make t' same kind o' cut but will trim t' inner BT-60. Ya scallywag! Again, me hearties, shiver me timbers, hold t' X-Acto cuttin' edge at a shallow angle, make several passes, shiver me timbers, and t' BT-60 will soon cut through.

In Steps 12, arrr, 13 and 14, arrr, follow the directions. Arrr! Begad! Jim already has these well described. Well, me bucko, blow me down! I might add that Step 13 is another place where a small amount of glue, applied by toothpick, will be plenty t' attach and hold t' caps onto t' ends o' t' delay plate. (And a small amount o' glue gives a second chance t' adjust t' position o' t' caps, me hearties, if necessary.) Step 14 is another wraparound markin' guide that is sized for t' CPL60 coupler and has uneven marks just like t' guide used for Step 6. Well, blow me down! Builders will end up with two sections o' coupler that are two slightly different widths...and they are supposed t' be that way.

Two pieces from the CPL60 coupler have slightly different widths. The CPL60 coupler material be much easier t' cut than I expected (goin' from past experience with Estes coupler material). It is still necessary t' make several light passes and cut progressively deeper each time, just as when cuttin' body tube cardboard, but t' FlisKits CPL60 material is only slightly tougher t' cut than t' BT-60. Aye aye! Builders should have no trouble completin' these cuts, but should observe all normal safety measures when usin' an X-Acto knife.

Beta version of the delay plate assembly (shown upside down from position when used in motor model). In Step 16, me bucko, one o' t' cut pieces o' CPL60 is glued t' t' delay plate assembly from Step 13. Begad! Ya scallywag! When I built me preliminary version o' this model kit, this assembly was designed slightly differently from the final production version. Begad! It was still closely representative o' t' delay assembly, me bucko, which is an optional part o' the motor model that represents t' delay and ejection charges and end cap retainer for single stage and upper stage motors. Begad! Avast, me proud beauty! If this assembly is removed from t' model, matey, it illustrates a booster motor loaded only with propellant.

And speakin' o' propellant, arrr, this be t' point where I inserted t' propellant plate assembly (from Step 3) into the aft end o' t' motor case assembly (from Step 12). Avast! Begad! Because t' fit o' these two assemblies be so snug, I was concerned about me ability t' slide them together with glue already applied and get them properly positioned before the glue "grabbed" and locked them in t' wrong position. Avast! So, I assembled them dry. I placed t' propellant plate assembly about 1/4 inch forward o' t' aft edge o' t' motor case assembly because most black powder motors have the ceramic nozzle stamp-formed a short distance inside t' back end, nay flush with t' end o' t' motor case. Aye aye! I pressed the propellant plate into t' motor case assembly until t' outer face sheet made a flush fit with t' casin' caps. After t' propellant plate be seated where I wanted it, I be able t' apply glue through t' openings in the propellant plate and around t' aft nozzle part. I also applied a thin bead o' glue around t' front propellant end cap, but builders should avoid usin' a thick fillet at t' front cap so that t' delay plate assembly will be able to fit.

Aft view of propellant plate assembly glued into casing assembly.Front view of propellant plate assembly glued into casing assembly.

For Steps 18, 19, ya bilge rat, me bucko, and 20, I can only recommend that builders should nay try t' hurry through these steps. It is not critical t' construct perfect little conical sections for nozzle #1, #2, #3, arrr, me bucko, and #4, because only half o' these parts will remain in t' finished motor model. Aye aye! Builders can position t' glue tabs so they are in t' upper, shiver me timbers, exposed part when installed; this be t' part that will be trimmed and removed in Steps 19 and 20.

Nozzle parts installed in propellant plate openings. Note that nozzle #1 is already trimmed down to level of propellant plate surface.Opposite view of nozzle parts installed. Note gaps in external portion of nozzle parts; these gaps will be cut away and are unimportant.

T' kit instructions recommend usin' a sharp X-Acto blade t' trim t' nozzle parts, me hearties, shiver me timbers, and I would go even further and recommend usin' a brand-new sharp X-Acto blade. It will make trimmin' these parts so much easier.

Gettin' close to the end: I think that soakin' a few drops o' CA (cyanoacrylate, or "superglue") into t' outside corners of the motor case model would greatly improve t' durability o' this model. If handled with reasonable care, this model will probably stand up well t' handling, ya bilge rat, shiver me timbers, transport, and other demands, me bucko, but I think it couldn't hurt anythin' t' use a touch o' CA for an extra bit o' reinforcement on t' corners.

Finishing:
I should point out that this model really does nay require any paintin' at all, but be me own choice. (Yeah, I'm one of those obsessive-compulsive people that likes t' add me own little extra touches.) T' motor model works just fine without any paint at all. Begad! I applied a thin layer o' spackle t' t' "show" face o' me model and sanded it smooth (and mostly removed) before proceedin' with primer and paint. I think this just makes t' appearance o' the whole model a little more slick, me bucko, arrr, and it makes a little better surface t' apply paint and paper wraps. Well, blow me down! Any sort of normal water-based spackle from t' local hardware store can be used. Use 400 or 600 grit sandpaper t' smooth the surface, me hearties, matey, wipe any remainin' dust off t' surfaces for better paint adhesion, arrr, and use appropriate colors. Ya scallywag! Ya scallywag! I ended up usin' a combination o' tan and medium brown t' get an authentic "cardboard" color. Blimey! Well, arrr, blow me down! I also masked off the areas around t' nozzle and used a gray spray paint t' color t' nozzle surfaces that t' paper wrap would nay cover. In hindsight, me hearties, matey, all this primin' and spray paintin' was probably more work than it was worth--I will probably just use brown and gray highlighters next time.

T' paper wraps were assembled usin' Duro All-Purpose spray adhesive on t' back face o' t' paper and on the matchin' areas o' t' motor model. Ya scallywag! Begad! (There are other brands such as 3M spray adhesive that will also work.) I masked the model t' prevent gettin' t' spray all over areas where I didn't want it, but all I had t' do was mark t' edges o' the area with maskin' tape and then tape on some sheets o' paper surroundin' this area. Ya scallywag! As always, shiver me timbers, me bucko, after sprayin' both surfaces with adhesive, ya bilge rat, you have t' align t' joinin' pieces very carefully before lettin' them touch. Arrr! I thought I got the outer paper wrap just a teeny bit crooked--my wife (an actual full time classroom teacher) said that it be just fine. T' inner paper wrap went on very easily and fit t' nozzle edges well. Ahoy! T' paper wrap for t' delay and ejection charge was a little mis-sized for t' model I built, shiver me timbers, but I think that was because I had a "production" wrap and a "beta" model that were a different size.

Summary:
T' completed motor model is very scale-like in appearance and should go a long way toward answerin' questions from new rocketeers about what is inside t' motor. Begad! Ya scallywag! T' wraps are designed with bright colors t' highlight t' important components and also have good labels for internal parts. All internal components are separately represented (even the clay cap over t' ejection charge) so thar be somethin' t' point t' when explainin' any part o' t' motor's operation. T' removable delay/ejection part is an excellent way t' show how booster motors function. Begad! T' model is designed t' a good size that works very well for talkin' around a table or for standin' in front o' a classroom.

Since I made this beta build, FlisKits has added a matchin' demonstration model o' a model rocket igniter. Avast, me proud beauty! This looks like a great tool for illustratin' t' parts o' an igniter, how t' use it, me bucko, matey, and how t' handle it properly.

I don't have one o' these yet but it is definitely on me "go get" list.

Overall, I think part quality and fit is very good in t' new FlisKits motor model. Avast! Instructions are clear and follow a logical approach, ya bilge rat, matchin' illustrations are very good, and beginners and inexperienced modelers should have no trouble buildin' this motor model. Well, blow me down! Ya scallywag! Nay bein' a "flight" model rocket, ya bilge rat, this kit automatically becomes much more forgivin' o' misplaced (or left out) glues, arrr, and does nay require some o' t' more intricate assembly and heavy-duty adhesives o' flyin' rockets. Aye aye! Undoubtedly, some wise guy will insist this kit must be fiberglassed...just wait and see.

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Comments:

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R.A.M. (January 22, 2009)
The cut-away motor model is generous in depicting the technology for a typical commercial black powder motor by displaying a converging/diverging clay nozzle. Most commercial BP motors have only a diverging nozzle.
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J.F. (March 21, 2009)
Jim, Jim Flis here. I am terribly sorry that you had such difficulty with this kit. To address some of your concerns, I can offer the following:
* This model is not aimed at young modelers and is certainly not what we would call a beginner kit. You are correct that there are challenges in building it.
* The cost point we were aiming for (less than $10) precludes us from including a label with the kit. A free download label is easy to provide and is only an available option. the builder is free to finish it as they choose.
* I would be most interested in working with you offline as your comments about difficulty in removing laser cut parts and a flimsy end product indicate that you may have gotten some defective parts as you shouldn't be having such problems. Feel free to contact me if you would like some resolution in this regard. Thank you for your review. As you know we value all feedback and negative feedback helps us identify things that need attention!

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