Vogon Poetry - 2 stage - old thread

I hope the nose won't be smashed. Speaking of smashed, you should have some smashed scintillating jewelled scuttling crabs around the base of the rocket.

I'm watching...It looks like yours will be bigger than mine now. I suppose I ought to get to work.

Nice interstage.

I am going to get Erik to work on the centering rings for the inter-stage. See if he can do them by the meeting on Thursday. If so, I will bring the rest of the parts for the inter-stage and we can have a dry fit and see how it looks, and feels.

In theory, this is not much more difficult than the smaller 54mm two stagers we have. Same electronics, etc.
'Running the numbers', I am finding that the stresses may be a tad more than we have seen so far. That is why I am focusing on the inter-stage. All those stresses have to pass through the inter-stage instead of interfering with it. Any slight inconsistency with the that and we are, as the English say, "Completely and utterly buggered"

Dan, it really shouldn't take that long. There are no fillets, not major fabrication except for the inter-stage, all the rest of the bits hopefully just slot together. Then I loose Pete with his rivet gun.. bwahahaha

Interstage to copy


poor nose cone that is gonna get chopped up for new interstage

update on sim and interstage design.

View attachment Vogon Booster.eng

View attachment Vogon Poetry.ork

An now the next iteration of the interstage design. I spent some time talking to Erik (emckee who is up there is post 2 chowing on popcorn) and we talked over the interstage. Strength and rigidity were the keywords. Now we are going to work with multiple 1/2" centering rings and 1/2" spacers (cut from spare 1/2" centering rings) to build up a solid structure between the internal tube (coupling to the sustainer and acting as AV bay in lower section).
We weren't even happy with this, and so upped the allthread to six lengths of 8-32, at 60deg intervals around the inner tube. The allthreads will run inside of the interstage, seating in an epoxy puddle at the front end, and then sticking through the rear bulkhead to facilitate attachment at the rear end. This whole setup will run through the centering rings, etc, to form a rigid internal skeleton, with centering ring 'ribs'.
I am thinking that I am going to build the whole internal structure first, before slotting it into the hacked off nosecone/transition. Then inject epoxy in through a hole or two in the fiberglass wall to build a large internal fillet around the front end, locking everything together. Then use expanding foam to fill the rest of the void. This will then turn the whole of the interstage cylinder into one solid piece. That aint gonna bent or flex!
We may be over engineering this section, but, we are doing it for damn good reason!

Both Erik and I are going to start cutting rings tomorrow. I am hoping that we have a dry fit in a few days.

Does anyone see a reason to fiberglass those allthreads to the outside of the center 3" tube? Or is that really going overkill??

I am going to start posting the files in OpenRocket format, thinking that more people have access to that than RockSim. Plus, I can start making it all pretty.

as always throughout my build posts, if you see improvements, or have comment, feel free to post.



View attachment 3 to 4 interstage coupler.ork

Seems like sort of a complicated coupler? If you can get a little more of the upper motor overlapped with the lower air frame, you could simplify things. The pics show a couple recent designs - not much more than motor adapters.

Jim

Talked with Erik and it got simplified a whole lot. Thanks for the comments and especially the pics.
I am seeing sustainer stability issues with the 3" fincan, so, that is not going to happen.
I have an old set of 5" Jart fins that would be perfect for building another fin can if they were cut down a little.

Hmmm... one of the things that was left here by Pete as an example of an interstage.... well.... i just seen some use for it other than as an example.


Well... it seems that the narrow end of that is 54mm tubing, and the rear fits into a 3" body tube.
Do I have anything.... oh... yup..


Oh look at that... the Loki 54mm M hardware slips straight in there.

NO - before you start checking pace makers and calling authorities to an unknown location in rural Oregon.... I am looking at a pair of two stagers.... NOT a three stager!!

Not yet.

Maybe BALLS 2018, but nope. My BALLS 2017 project was the minimum diam 54mm M, Max Q fincan, doing it the 'easy way', but, they stack!

So.. that aside, let us get back to the interstage.
I collected lots of rings from Erik, and a bulkhead or two. 1/2" stuff!


I have tubing.


OK... i have already cut those down so things fit.


I need to get a few shims and such so that I can mount a couple of screw switches in the space between tubes, drill access holes, and slot this into a 4" section of tubing.
That and glue the thing together, and we nearly have an interstage.

Yes, thank you Jim! Sometimes I get into the focus and start to overengineer. This is so much simpler, and probably just as strong.

Salvage-1 said:

Yes, thank you Jim! Sometimes I get into the focus and start to overengineer. This is so much simpler, and probably just as strong.

Click to expand...

No problem! I can't really tell all of the design objectives that you have for this, but one thing I noticed was that the "switchband" on the coupler was several inches long? I know that I typically try to reduce the length of this to the minimum because that is one factor that determines how much of the sustainer motor that can be buried into the top of the booster tube. Might be some room to negotiate there?

Also, just FYI, I also use Rocksim in my designs because it is easier to use that to mess around with the CG's of the different stages with different motors. RasAero requires that the CG information include the motor, which is cumbersome for evaluating different motors. I also compare the resulting CP/CG information for both models as a kind of QC check on the design inputs.

Your comment about three-fin stability also caught my attention. I had several flights a few years back that came apart near the end of the sustainer motor burn. I was never able to identify the cause in some cases. I think I'll go back and review the stability information for those flights, now that the models are better, and see how they look. I have another 3-fin flight coming up that is close to Mach 3. I think a little more research would be prudent.

Jim

JimJarvis50 said:

Your comment about three-fin stability also caught my attention. I had several flights a few years back that came apart near the end of the sustainer motor burn. I was never able to identify the cause in some cases. I think I'll go back and review the stability information for those flights, now that the models are better, and see how they look. I have another 3-fin flight coming up that is close to Mach 3. I think a little more research would be prudent.

Jim

Click to expand...

The stubby fincan looked fine for the upper stage. Then I started doing a plot showing stability over the flight time. Boom... there is a point just at Mach when the stability drops down to 1.2
I am not happy with 1.2 so designing another fincan for the sustainer.

op:

emckee said:

op:

Click to expand...

stop eating all the popcorn and get back to work!

Be very afraid, the Vogon will fly!



Currently though, the there is a strike at the Vogshere 2 shipyards as there is a 'hippy festival' going on somewhere on Vogshere 3, and the Captain has gone insane, and is practicing necromancy and its accompanying culinary arts.



Therefore we had go so to the shipyards of New Burbank, Osiris, and reuse one of their boosters. This booster is outfitted with a 75mm AP plasma flux drive, and will be adequate for the boilerplate flight planned in a couple of weeks.

JimJarvis50 said:

... one thing I noticed was that the "switch-band" on the coupler was several inches long? I know that I typically try to reduce the length of this to the minimum because that is one factor that determines how much of the sustainer motor that can be buried into the top of the booster tube. Might be some room to negotiate there?....
Jim

Click to expand...

Noted. See pics.

Yup, after feeling like I have been playing Jenga with these centering rings for the last two days, I think I have a way to get his working.....






The thin dark rings are 4" birch ply centering rings, the fatter rings are 1/4" and cut from "no-idea" quality ply. The fatter rings are cut roughly coupler sized, the darker rings will engage the inner surface of the booster body tube.
Ignore the coupler sticking out of the rear of the tube, it hasn't been cut flush yet.
On the top of the coupler, sits a stepped bulkhead (coupler sized 1/4" wood and 1/8" fiberglass airframe coupler), coupler and bulkhead get glued in place, bulkhead will have hole so that the separation charge wire can fit through.
Only the rear 3 rings are glued in at the moment.

So, as is, it is right one 1lb weight. Need to add switches, electronics, etc., and I am going to drill a hole alongside the outside of that 3" tubing, through the wood, and I am going to place the antennae for the TeleMetrum in there.
At the aft end of this block of wood, I will be putting in six 8-32 brass inserts so that the rear bulkhead with recovery ring can bolt directly on.


.... which then led to me having a sleepless night last night when, just as I was falling asleep, I realized that this only works for snap-ring hardware..... and we have an AT 1297 to burn in the upper stage.
Needs to think of that now.

..cont

In this pic you can see how the interstage will be drilled. The three lower sets of holes will be drilled for static ports. The position of the upper three will be traced onto the 'switch band' and holes will be drilled for sheer pin placement (again, thank you Jim for that idea)

Salvage-1 said:

..cont

In this pic you can see how the interstage will be drilled. The three lower sets of holes will be drilled for static ports. The position of the upper three will be traced onto the 'switch band' and holes will be drilled for sheer pin placement (again, thank you Jim for that idea)

View attachment 323498

Click to expand...

On my current 3rd stage, I have shear pins from the interstage coupler into the motor case. This is necessary since with a three-stager, you don't want the 3rd stage drag separating when the first stage motor burns out (that would be bad). This is maybe a little less important on a two-stager, where drag separation of the stages is usually OK. Anyway, the first time I did this, I filled the thrust ring groove with epoxy and then shear pinned into that. Then, I figured out that I could go through the case at that point and still be outside of the nozzle O-rings. So, that's how I'm doing it now.

Jim

Salvage-1 said:

.... which then led to me having a sleepless night last night when, just as I was falling asleep, I realized that this only works for snap-ring hardware..... and we have an AT 1297 to burn in the upper stage.
Needs to think of that now.

Click to expand...

You could just machine the aft closure down, or replace it with the ring for the floating fwd closure... It fits, I've seen it assembled the wrong way by accident.

And you can drill through the aft closure for shear pins too...

Salvage-1 said:

Everything has been signed in triplicate, sent in, sent back, queried, lost, found, subjected to TAP inquiry, lost again, and finally buried in soft Pete (he didnt like it) for three months, and recycled as starters for research motors.

Click to expand...

.... oh Belgium frood, just Belgium, just this morning I intercepted a transmission on the sub-ether radio.

As of February 6, 2013, the C3RC has also been tasked by the TRA BOD to review all non-Class 3 flights
attempting altitudes over 50,000' AGL.
The increased interaction between the FAA and sister government agencies requires that all rockets,

regardless of impulse, designed to fly above 50,000 feet (AGL) be submitted to the Class 3 Review

Committee for dispersion analysis. This is an internal Tripoli decision and not a request by any Federal

agency

Click to expand...

Seems that there may be paperwork to do.

Latest new -

Captain still missing, presumed half baked (he is a cook at the fair... I am playing on that side of the joke)
Cabin Boy Emckee just texted from a location called 'Florida'. I hope that he is only going there to study rockets.

Name change of rockets.

54mm Min diameter - Barnards Star ( flown with Vogon Poetry as its booster )
75mm Min diameter - Vogon Poetry
98mm Min diameter - Dentrassi ( BIG booster )
75mm in 4" - The Thumb ( booster for first set of test flights )

So, on THIS thread, we have "The Thumb" (which is a used Firefly class booster) staging to "Vogon Poetry", but that won't get us high enough, to do that we need "Dentrassi" staging to "Vogon Poetry"

When all this mess is done and cleared, and we get them all back, we can try a flight with "Vogon Poetry" boosting to "Barnard's Star"

... and if you don't understand any of the above :cyclops: please find another build thread

A BIG shout out to Cameron Tinder of Tinder Rocketry https://www.tinderrocketry.com/

He has donated a Peregrine CO2 system for use in this project.



Thank you very much Cameron, and thank you for your continued support of OROC.

so..... I broke the rule of 'no major purchases' and just ordered a custom fin can from Mike at Max Q Aerospace. It is a clipped swept delta, like the Jart, or front fin of a Darkstar. Aluminium with both leading and trailing edges wedges.

Why? I want this rocket to have a good flight and I want to get it back.

Latest iteration of the design - need to redesign upper AV bay to get the Peregrine in there.



---
edit

also.. this needs some HHGTTG'ifying (yeah, I get to make up a word), and we all love Stickershock! So... talking to Mark about some coverage



and it's BALLS, so the crew may need T-shirts

Salvage-1 said:

Everything has been signed in triplicate, sent in, sent back, queried, lost, found, subjected to TAP inquiry, lost again, and finally buried in soft Pete (he didnt like it) for three months, and recycled as starters for research motors.

Click to expand...

So this one yet again comes around to bite my backside. Certain forms needed submitting 90 days prior to flight.

Not going to stop the build or shakedown flights..... coz i had prepared and have the 75mm in 4" airframe booster on hand.

Salvage-1 said:

So this one yet again comes around to bite my backside. Certain forms needed submitting 90 days prior to flight.

Not going to stop the build or shakedown flights..... coz i had prepared and have the 75mm in 4" airframe booster on hand.

Click to expand...

I doubt this would be an issue. If you are not Class 3, then no one will even look at your paperwork until a week or so before the launch. You didn't get a complaint did you?

Jim

Not a complaint, but I did read that anything no matter what impulse, that is designed to go over 50,000K needs this submitted to TRA for Class 3 approval. Doesnt bother the FAA, but I beleive this is just Tripoli internal.

----
Edit

Even though this started as an idea to fly MD 98 to MD 75, I see no reason to rush this. We still have a BALLS flight no matter what. If we stick to the black booster (The thumb), to the 3" VP, we can keep that well under 50K. Plus, if I interpret this correctly, since that 50K is not the actual waiver limit, we are not restricted to 10% underneath or whatever it currently is.

So... a LOT can still be done with 75mm to 75mm and keep well under.

but most of all

DON'T PANIC

Salvage-1 said:

Not a complaint, but I did read that anything no matter what impulse, that is designed to go over 50,000K needs this submitted to TRA for Class 3 approval. Doesnt bother the FAA, but I beleive this is just Tripoli internal.

Click to expand...

Yes, that's correct. Anything over 50K needs to be reviewed. However, my experience is that the committee will deal with the Class 3 flights first and then the 50K+ flights after the Class 3 flights are completed. It turns out that the timing for reviewing the 50K+ flights is often not very far before the launch. So, although the paperwork is requested 90 days in advance, it's likely that not much has been done with such projects at present. I would not let this hold you back from submitting if that's what you want to do.

Jim

Go ahead, submit and ask for forgiveness, cos they can always say "nope", and go prepared with the smaller booster.

JimJarvis50 said:

Yes, that's correct. Anything over 50K needs to be reviewed. However, my experience is that the committee will deal with the Class 3 flights first and then the 50K+ flights after the Class 3 flights are completed. It turns out that the timing for reviewing the 50K+ flights is often not very far before the launch. I would go so far as to say that on one of my flights, the review occurred while I was traveling to the launch. So, although the paperwork is requested 90 days in advance, it's likely that nothing has been done with such projects at present. I would not let this hold you back from submitting if that's what you want to do.

Jim

Click to expand...

Salvage-1 said:

Go ahead, submit and ask for forgiveness, cos they can always say "nope", and go prepared with the smaller booster.

Click to expand...

Yep. Forgiveness, complete information provided, you'd be good I think.

I suspect that not much will be done on any of this until a call is made on the launch August 1. Just my guess.

Jim

late to the party, but props on the names and references...wish I could see this fly, but alas, I'm stuck cleaning some hessian wall weave.

DON'T PANIC!

Absolutely nothing has been done since last update... honest.
I need to cut some fiberglass tubing to replace the bluetube, maybe.
Mike at Max Q Aerospace got these custom cans to me in 7 days! Honestly, that dude is FANTASTIC!
I opted for the 'raw' finish. We can always have fun polishing them later, it was all about getting them to me in soon. Seeing as he quoted lead time as 3 weeks, this is 2 weeks ahead of schedule!
Plus... it looks SWEET! I need to drill and install the screws that secure the whole thing to the motor but, fincan is in place.