7.5" Modular Booster / upscale Estes SM-3 Seahawk - FINISHED!

[qquake2k]

Thanks for the advice, Rex. I took extra care to leave a little flat spot around the perimeter to avoid a sharp edge. Centering rings have historically been my nemesis. I got complacent (and rushed) a while back, not clamping one down when drilling out the 98mm center hole. It got caught in the drill press, spinning and whacking my thumb several times before taking off across the garage and putting a serious dent on the inside of the door. Live and learn.

:surprised:

Ouch.

 

[SMR]

Ouch.

Well, I still have all my fingers and toes, 'cause I'm working very slowly and not rushing anything. Here is where we stand today. I cut the slugs for the sustainer's strakes. Still need to angle the leading and trailing edges, as well as the transition between the 3/4" piece and the 1 1/4" piece, before glueing them to the body tube. They will be surface mount only, not TTW. The remaining photos show the two rockets (booster and sustainer) full assembled for the first time. (Finally got that back-ordered 5.5" coupler!) The booster section is on it's way out the back door to get her first coat of filler primer. In the background is another distraction... my Gizmo XL DD, which will fly at MWP X and has taken priority over the Seahawk, which now is a go for Thunderstruck 4. Feels just like NASA, juggling missions around to fit launch windows. (As well as constantly being over budget and behind schedule.)

 

[SMR]

... I'm working very slowly and not rushing anything

A bit of an understatement. My apologies for the break, I got a little stuck on the interstage coupler, but have now solved one of the problems* and can forge ahead. The transition for the ISC has been cut to fit, and it is now awaiting the 4 custom centering rings to finish. I also made a template for the strakes, and have marked them to cut the leading and trailing edges to match.

* The spine of the ISC is basically three 12" lengths of G-10 tubing... a 5.5" coupler, a 5.5" body tube, and a 4.0" body tube... each overlapping 6" with the next. A 5.5" to 7.5" transition fits over the forward 4" of the 5.5" body tube, so that the 5.5" coupler sticks out the top to hold the sustainer. I SHOULD have installed the transition PRIOR to the 5.5" coupler, which would have made it much easier to cut the transition (originally a tailcone from a Polecat Bullpup) flush with the edge of the 5.5" body tube. By attaching the tubes first, I had to cut the transition a smidgeon at a time and trial fit after each cut, to avoid cutting off too much. Very time-consuming and frustrating, but a lesson in there somewhere.

 

[bradycros]

I'm working very slowly and not rushing anything.)

My apologies for the break, I got a little stuck on the interstage coupler, but have now solved one of the problems* and can forge ahead.

I understand compleatly. Sometimes stepping away from a project, regurdless of the lenght of time, can be the best thing to do.

Looks like you dreamed up what you where waiting for. Good looking graphics too!

 

[sodmeister]

I`m glad to see you are back at this project also ,good for all of us !

I`m not sure if I asked you before ,but may I ask where you purchased those router bits you used to bevel the fins ,as I`m having a bugger trying to find them.

Thankyou

Paul T

 

[Eat, sleep, and Fly]

a 5.5" coupler, a 5.5" body tube, and a 4.0" body tube... .

What is the 4" tube for? Is it an AV bay?
Also, is the sustainer's motor mount 75mm, or 98mm?

 

[SMR]

I understand completely. Sometimes stepping away from a project, regardless of the length of time, can be the best thing to do.

Looks like you dreamed up what you were waiting for. Good looking graphics too!

Thanks, Todd. Some time off, in keeping with my "goals" vs "deadlines" preference, helped a LOT. Now I have a renewed energy and a fresh perspective.

 

[SMR]

I`m glad to see you are back at this project also ,good for all of us !

I`m not sure if I asked you before ,but may I ask where you purchased those router bits you used to bevel the fins ,as I`m having a bugger trying to find them.

Thankyou

Paul T

No problem, Paul. It may have come up before, but the answer is buried in another thread and long ago, so worth asking again. I use a straight Carbide bit with a 1/2" shank, available from Rockler Woodworking Supply. I'm sure they'll ship to Canada.

My router bolts under my table saw with the bit facing up, and I use a fixture attached to the rip fence to guide the fin stock. I've used both the 15° and the 22.5° bit. The 15° bit gives a nicer bevel on fins up to 1/4" thick, but takes off more material, so I use the 22.5° bit on thicker fins.

https://www.rockler.com/product.cfm?page=5503&filter=router bit

 

[SMR]

What is the 4" tube for? Is it an AV bay?
Also, is the sustainer's motor mount 75mm, or 98mm?

Yup, the 4" tube inside the interstage coupler is indeed the avionics bay. The combined stack will use 4 separate avionics sleds in three separate bays...

One in the booster (2 MAWD's) to manage recovery. (dual deploy via Defy Gravity Tether)
One in the ISC (2 MiniTimer 3G's) to manage staging separation.
Two in the sustainer. One (2 MiniTimer 3G's plus one of Frank Hermes' RockeTiltometers) for second stage ignition, and the other (2 SL100's) to manage recovery. (via conventional dual deploy)​

The sustainer has a 75mm mount. Mostly for personal preference. This is a test-bed for a future rocket, so playing it a little safe here. (Not sure if we are ready to declare yet, but I am in the design phase of a long-term joint project with Jackson to build and fly a 98 to 98, with an end goal of an N5800 booster to an O3400 sustainer. Cats out of the bag now.) Anyway, the 75mm motor in the Seahawk's sustainer allows room for a 98mm extension tube, between the 75mm motor tube and the 5.5" body tube. The 75mm to 98mm ring at the aft end of this tube provides a mounting surface for the Aero Pack flange, and the tube itself provides physical structure to carry thrust forces forward to main centering rings and the fin tangs, without relying solely on epoxy joints. It also allows room for the two conduits used to carry igniter leads down alongside the motor, and allows a wider tang on the TTW fin, to compensate for it's reduced length, a by-product of the aft ring being inset 7" to clear the interstage's coupler. Lastly, IMHO, a 75mm motor in the same impulse range has a better mass distribution profile for Cg issues than a corresponding 98mm motor (long and skinny vs short and fat means some of the weight is more forward.) This project had some limitations imposed on it by attempting to maintain the proportionate scale of an existing Estes kit.

 

[sodmeister]

Ahhhh Rockler ,thankyou Sather !

Paul T

 

[SMR]

I'll have to make a new altimeter sled for these two projects, as my current sled is designed for tether recoveries. For those, the avionics bay is built into the lower body, with the switches at the bottom to be accessed below the body joint. I have been able to use them for conventional dual deployment rockets, also, by drilling access holes through the motor section of the rocket body, to access the switch holes in the coupler sleeve of the av bay. I would prefer to not do to all my rockets in the future, though, so the next generation av sled will have switches in the middle to be accessed through holes in the avionics bay's band.

This post is applicable to both active threads I am running, so it will appear in both. This week I am starting to put together my 3rd generation of avionics sleds. My current revision (#2) uses low-mounted POPO switches, and LOC 1/4" launch lugs for attachment to the all-threads. As mentioned previously, I am moving the POPO switches higher, to line up with the center band in my conventional av bays. And, while I haven't had a lug come off yet, I have noticed the insides are starting to fray from abrasion as they are put on and taken off the 1/4"-20 all-threads. So the next batch have a piece of angled aluminum at each end in lieu of the cardboard lugs. Rather than measure and mark each one individually, I made a quick jig out of some scrap 1/4" plywood. All I had to do then was mark the centerline of each board, hold the jig on, and transfer the two mounting holes to each piece of aluminum. I drilled a pilot hole first, using a small bit to get the best alignment possible, then increased a few bit sizes until the 17/64" final hole. Last picture shows one of the sleds trial fit on the all-threads of a 4" bay. Next up will be mounting the POPO switches, terminal strip, circuit boards stand-offs and battery box.

edit added... my original av bays had either 2" or 2.75" spacing of all-threads. (I couldn't make up my mind). So, the sleds had two sets of lugs, to accommodate either. I have since systematically retro-fitted all my bays to 2.75" spacing, which will make drilling alignment holes easier, as well as freeing up more acreage on the board.

 

[SMR]

Progress update

I made a template for and started cutting the custom rings for the interstage coupler. Two have 4" holes, the other two have 5.5" holes, all with the outside dimensioned to fit into the Polecat 7.5" coupler. In the second thru fourth pictures, the 1st (aft) ring is finished and I am beginning to assemble / trial fit the components together. Finally, I cut the leading and trailing edge angles on the sustainer's strakes. Yet to finish are the bevels on the angled cuts. These are going to be difficult, as they need to be done as compound miter cuts, like crown molding, but at non-standard angles. Am leaning toward making jigs and running them across a disc sander rather than attempt it with a router.

 

[sodmeister]

You sure do some awesome work Sather !

I`d like to meet you someday !

Sure wish you`d post more often.

BTW- I ordered those router bits from Rockler ,thanks for the tip !!!!

Take care

Paul T

 

[SMR]

You sure do some awesome work Sather !

I`d like to meet you someday !

Sure wish you`d post more often.

BTW- I ordered those router bits from Rockler ,thanks for the tip !!!!

Take care

Paul T

Thank you, Paul. It would be great to meet you, too. Any plans to attend a stateside launch in the future? I have been to Winnipeg, far too many years ago. Beautiful country with friendly people. Nice place to live and raise a family.

I post at about the same rate I build... slowly and in short spurts of energy with long voids of work, family, and a few other hobbies that tend to distract me.

P.S. Very much enjoyed your album of model aircraft.

 

[sodmeister]

Thank you, Paul. It would be great to meet you, too. Any plans to attend a stateside launch in the future? I have been to Winnipeg, far too many years ago. Beautiful country with friendly people. Nice place to live and raise a family.

I post at about the same rate I build... slowly and in short spurts of energy with long voids of work, family, and a few other hobbies that tend to distract me.

P.S. Very much enjoyed your album of model aircraft.

Yov`ve been to Winnipeg ? wow ,you don`t hear that too often from my cousins South of the border !

We are fortunate to have many good hobby shops here ,but nothing high power related.It is a good place if you need work ,lots of that and if you like the great outdoors (fishing ,hunting ,water sports camping or just plain solitude) drive 45 minutes in any direction and you have it.

Our club has a great high power launch field 40 minutes South of me ,4 square miles of flat as a pancake prairie and our own restricted airspace.

I hope to attend a launch in the US some day ,that would be great.Sure would be a treat to meet some people from the forums !

I`m like you ,I build in short spurts with too many projects on the go.

Thanks for having a peek at my albums ,another one of my too many hobbies LOL

OBTW- I sure could have used the router bit from Rockler today for the leading edges of my hellfire fins ,would have saved me much time.I did order them ,just need to pick them up from my US postal address ,going to Grand Forks ,ND in 3 weeks.

OH yah....I like that branding iron you use to mark your wooden parts ,very cool.I`d like to get one of those !

Take care Sather

Paul T

 

[SMR]

Rings

Lacking a plunge router and the accessory with which one can make custom rings the easy way, I have to make do with tools on hand. For bulk plates and the outside of centering rings, I cut out the rough shape (slightly large) as carefully as possible with a jigsaw, then put on a spindle and turn by hand on a disc sander to get a perfect circle. There is a little trial and error to get a good fit, taking off a tiny bit at a time to avoid the worst case scenario - taking too much off.

For the inside hole in centering rings, the process is similar. Cut out the rough hole (slightly small) as carefully as possible with a jigsaw, then put on a different sort of spindle (one that holds the outside edges) and turn by hand against a sanding drum to get a perfect circle on the inside. Once again, it takes a little trial and error to get a good fit.

Finally, the rings are finished and I can begin final assembly of the interstage coupler.

P.S. Yesterday was our 13th anniversary, and my wonderful and supportive spouse surprised me with an M1300! Wow, so much for the traditional list... (paper, linen, crystal, china, etc.). Thank you, honey!

 

[blackbrandt]

P.S. Yesterday was our 13th anniversary, and my wonderful and supportive spouse surprised me with an M1300! Wow, so much for the traditional list... (paper, linen, crystal, china, etc.). Thank you, honey!

Dang! I can't wait to get married!

 

[SMR]

Dang! I can't wait to get married!

Patience, grasshopper. You must choose wisely.

 

[blackbrandt]

Oh, yeah...
https://www.rocketryforum.com/showthread.php?34014-how-do-you-justify-this-hobby-with-your-spouse

 

[dixontj93060]

[BmRings[/B]

Lacking a plunge router and the accessory with which one can make custom rings the easy way, I have to make do with tools on hand. For bulk plates and the outside of centering rings, I cut out the rough shape (slightly large) as carefully as possible with a jigsaw, then put on a spindle and turn by hand on a disc sander to get a perfect circle. There is a little trial and error to get a good fit, taking off a tiny bit at a time to avoid the worst case scenario - taking too much off.

For the inside hole in centering rings, the process is similar. Cut out the rough hole (slightly small) as carefully as possible with a jigsaw, then put on a different sort of spindle (one that holds the outside edges) and turn by hand against a sanding drum to get a perfect circle on the inside. Once again, it takes a little trial and error to get a good fit.

Finally, the rings are finished and I can begin final assembly of the interstage coupler.

P.S. Yesterday was our 13th anniversary, and my wonderful and supportive spouse surprised me with an M1300! Wow, so much for the traditional list... (paper, linen, crystal, china, etc.). Thank you, honey!

Well maybe next year Tricia can get you a plunge router and Jasper Jig...

 

[sodmeister]

Sather ,that`s beautiful my friend ,as that`s how I got the finished shape to my tail cone on my Hellfire !

To see that ,you would have sworn ,that jig and process was in my own shop.

Bravo :handshake:

Paul T

 

[SMR]

Finished with the ISC internal rings. The forward edge of the lower ring was originally tacked on with a small fillet of JB Weld, while the lower edge got a healthy fillet of West Systems epoxy with chopped carbon fiber. This left a larger surface on the forward side of the lower ring to attach hardwood blocks, one on each of the four cardinal points, between the two top rings. (The hardwood blocks are for spacing, strength, and also to hold a "high" rail button. Since the combined stack is pretty tall, I wanted to mitigate side loads on the booster's rail buttons while it sits on the pad in any cross wind.) After the upper ring was in place, all edges got the full West epoxy/ chopped carbon fiber treatment.

I've been looking at the possible failure modes with this setup. The top two rings are 7.5” outers with 5.5” inner holes. They sit directly under the 4” long body band. Cosmetically, the top 1.25” of the body band covers the shoulder of the tailcone being used as a transition, while the bottom 2.75” covers a portion of the coupler which serves as the ISC shoulder into the booster. But structurally, the body band fills an important function in the launch of the combined stack. The weight of the sustainer sits on the 5.5” G-10 tube structure that runs down the inside of the ISC. This is in turn passed to the booster’s upper body tube by the coupler’s body band. Should the band break loose under boost at launch, the sustainer would fall through the booster’s payload tube, losing vertical alignment in the process. Not a pretty sight. So, not to rely on epoxy strength to carry structural load, the band will be thru-bolted to tie the structure together. Screws will run through the band, coupler, rings, into the 5.5" G-10 body tube and coupler, where they overlap.

One last trial fit of the entire assembly before epoxying everything together. The top (exposed coupler) is a critical mating surface to the sustainer, and is masked off here to avoid any contamination during the inevitable filling and sanding to follow.

 

[SMR]

Sather ,that`s beautiful my friend ,as that`s how I got the finished shape to my tail cone on my Hellfire !

To see that ,you would have sworn ,that jig and process was in my own shop.

Paul T

You are one of the true great craftsman among us, Paul. I have stolen many ideas from you. Keep 'em coming.

You know......I think I spend more time making fixtures and jigs than I do building rockets ! But it`s still fun :wink:

Paul T

 

[SMR]

Rough assembly of the ISC is complete. Filling and sanding to be accomplished outdoors, as it will create a lot of dust and I'll get in trouble. (No more motors for me!) Then installation of the ring of screws and the rail buttons. So, this seemed like a logical time to trial fit the ISC to the sustainer and booster. Individually, as I am still restricted to a very small part of the basement and space is a limitation. Nice snug fit between the sustainer and the 5.5" coupler sleeve. Slightly less snug between the booster and the 7.5" coupler shoulder, but that joint will be taped and pinned to prevent drag separation after booster motor burnout. Notice the spacing between the transition and the sustainer is slightly different between the larger and original versions. I moved that length from the front to the rear of the transition, to create a little more length in the booster than the Estes version allowed. It seemed the easiest compromise to keep the overall proportions in line, with the added benefit of improving the stability margin.

 

[SMR]

Two days to complete one hours work...

You know......I think I spend more time making fixtures and jigs than I do building rockets ! But it`s still fun :wink:

Paul T

Well, I hinted at this a few posts ago, but wanted to wait until I had made some progress before posting results. I had to put bevels on the leading and trailing edges of the strakes, to match ones previously put on the sides. It would be almost impossible to use a router to do this, as they are very short bevels, so not much length to hold against the router fence. I toyed with the idea of using a compound miter saw, but felt I would have more control just sanding the bevels on a disc sander. But how to hold the alignment to ensure proper and repeatable orientation of the piece.

"I'll just make a jig!" I have a bunch of scraps here from unrelated projects. A flat surface aligned with the angle of the bevel, and an adjustable fence to line up the piece for each of the 3 different angles. (Well, actually 6, because left and right hand sides needed to be done mirror-imaged.)

Version 1. Okay, high school Geometry lesson here. I had put a 15° bevel on the sides of the strakes. So, what angle should the flat surface be? My first shot at it was... 45°. No real good reason why, just not paying attention. Obviously did not work.

Version 2. A little more math in the process. 90° minus 15° equals... 75°. Rather than tear the whole thing apart and start over, I just added 30° wedges under the 45°'s. Getting closer, but the piece of wood I used as a fence was now too thick, and hit the disc sander's face prior to the strake coming into contact.

Version 3. Voila! A shim made a perfect fence, as it gets thin at the front edge and does not infringe into the sander's plane.​

End results are some acceptable beveled edges. Especially happy with the middle edges, as they have to line up with bevels at the lower level. Now to epoxy them in place and add fillets.

 

[sodmeister]

Now that`s a bevel...bravo old chum !

That`s kind of what I made(OK,exactly LOL) to bevel the leading edges of the Hellfire fins ,but I used it on my router table ,as all I had to use was a straight cutting bit.

I`m going to the US in two weeks (I live 40 minutes from the border ,North Dakota) for a little shopping and R & R ,and while there will make a stop to my US postal address and pick up my Rockler router bits you told me about ,amongst other rocketry related items !

The bits from Rockler will make things easier ,but I want to make a permanent bevel jig that will be adjustable ,so I don`t have to fiddle around with angles ,just hinged at the base and a slide/lock and wingnut/thumbscrew to lock the desired angle.

But of course ,not all can be done on the router like you discovered ,but a similar jig/fixture could be adapted to a sander quite easily(my sanding station, more specifically the disc portion has a miter slot in the tilting table)

I prefer to have the table on my disc sanded perpendicular to the disc face ,so a sliding ,adjustable jig would be nice for beveling objects such as your strakes ,plus if need be ,the sander table could be adjusted for clearances or fine tuning.

You have to like MDF and Baltic Birch for jigs and fixtures !

That reminds me ,my specialty wood shop has all it`s Baltic Birch on sale this week (1/8" up to 1" in 5 foot x 5 foot sheets) so a little shopping is in the works this morning !

Beautiful work Sather and the picutes ain`t bad either :wink:



Paul T

 

[SMR]

Well maybe next year Tricia can get you a plunge router and Jasper Jig...

I think tools would be a step in the wrong direction... I have her getting me motors!

With just a few exceptions, we could keep this going until our 40th. And we could fill in any gaps with clusters or staging...

1. I100-RL (CTI)
2. I200-W (AT)
3. I300-T (AT)
4. J400-SS (CTI)
5. J500-G (CTI)
6. J600-RL (CTI)
7. K700-W (AT)
8. L800-Classic (CTI)
9. L900-DM (AT)
10. N1000-W (AT)
11. N1100-Classic (moonburn, CTI)
12. M1200-SF (Loki)
13. M1300-IM/Dual (CTI)
14. M1400-Classic (CTI)
15. M1500-G (AT)
16. M1600-R (AT)
17. ----
18. M1800-FJ (AT)
19. M1900-BB (AMW)
20. N2000-W (AT)
21. M2100-G (AT)
22. N2200-Pink (CTI)
23. ----
24. M2400-T (AT)
25. N2500-Classic (CTI)
26. N2600-SK (CTI)
27. M2700-hybrid (Contrail)
28. N2800-WW (AMW)
29. N2900-Classic (CTI)
30. M3000-ST (AMW)
31. M3100-WT (CTI)
32. L3200-VM (CTI)
33. N3300-R (AT)
34. M3400-WT (CTI)
35. M3500 (Kosdon/AT)
36. ---
37. O3700-SK (CTI)
38. N3800-BS (CTI)
39. ---
40. N4000-BB (AMW)

 

[SMR]

I`m going to the US in two weeks (I live 40 minutes from the border ,North Dakota) for a little shopping and R & R ,and while there will make a stop to my US postal address and pick up my Rockler router bits you told me about ,amongst other rocketry related items !

The bits from Rockler will make things easier ,but I want to make a permanent bevel jig that will be adjustable ,so I don`t have to fiddle around with angles ,just hinged at the base and a slide/lock and wingnut/thumbscrew to lock the desired angle.

But of course ,not all can be done on the router like you discovered ,but a similar jig/fixture could be adapted to a sander quite easily(my sanding station, more specifically the disc portion has a miter slot in the tilting table)

I prefer to have the table on my disc sanded perpendicular to the disc face ,so a sliding ,adjustable jig would be nice for beveling objects such as your strakes ,plus if need be ,the sander table could be adjusted for clearances or fine tuning.

You have to like MDF and Baltic Birch for jigs and fixtures !

That reminds me ,my specialty wood shop has all it`s Baltic Birch on sale this week (1/8" up to 1" in 5 foot x 5 foot sheets) so a little shopping is in the works this morning !

Beautiful work Sather and the picutes ain`t bad either :wink:

Paul T

Welcome, Paul. I hope your visit is productive and otherwise uneventful. When I was a kid, we could drive across the border for lunch, with only one person having a driver's license for ID to cross both ways. Probably a bit more involved, now.

Yeah, MDF and birch plywood. Lots of leftover scraps from my train layout. My disc sander has a miter slot, also. I toyed with the idea of using it for alignment of the jig, but it was already way more involved than I wanted. If I was to make a permanent jig, definitely would have used it. And would hopefully have been prettier. But it fulfilled it's purpose and I feel better not wasting the scraps.

My local Menards used to stock 4' x 8' sheets of Baltic Birch, but a few years ago it became a special order item. So I bought the remaining sheets they had in stock. Will last me a looooong time.

 

[SMR]

Been attaching the strakes, 1 set per day. Roll it 90° and put another one on. Using the tried and proven method of clamping them with straight-edges to the fins, keeping everything in line. (You can never have enough clamps!) One more day to go, then I can start her fillets.

I put sets of rail buttons (1010 and 1515) on opposite sides of the sustainer, in the event I ever lose the booster, or just want to fly her single stage. I will probably just pull the buttons off and leave the holes marked with (shorter) screws when flying her as designed.

 

[CarVac]

I think tools would be a step in the wrong direction... I have her getting me motors!

With just a few exceptions, we could keep this going until our 40th. And we could fill in any gaps with clusters or staging...

1. I100-RL (CTI)
2. I200-W (AT)
3. I300-T (AT)
4. J400-SS (CTI)
5. J500-G (CTI)
6. J600-RL (CTI)
7. K700-W (AT)
8. L800-Classic (CTI)
9. L900-DM (AT)
10. N1000-W (AT)
11. N1100-Classic (moonburn, CTI)
12. M1200-SF (Loki)
13. M1300-IM/Dual (CTI)
14. M1400-Classic (CTI)
15. M1500-G (AT)
16. M1600-R (AT)
17. ----
18. M1800-FJ (AT)
19. M1900-BB (AMW)
20. N2000-W (AT)
21. M2100-G (AT)
22. N2200-Pink (CTI)
23. ----
24. M2400-T (AT)
25. N2500-Classic (CTI)
26. N2600-SK (CTI)
27. M2700-hybrid (Contrail)
28. N2800-WW (AMW)
29. N2900-Classic (CTI)
30. M3000-ST (AMW)
31. M3100-WT (CTI)
32. L3200-VM (CTI)
33. N3300-R (AT)
34. M3400-WT (CTI)
35. M3500 (Kosdon/AT)
36. ---
37. O3700-SK (CTI)
38. N3800-BS (CTI)
39. ---
40. N4000-BB (AMW)

L2300G (KBA Animal-compatible) fits in there.

Interesting how there is only a single K on the list, and L's take only a few spots.