Vogon Poetry - 2 stage - old thread

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
We didn't get it in the air today. Pete E made a valiant effort to finish the HEI and got the motor built, but with RSO duty, club secretary and BoD questions, the day just seemed to fly past (pun intended). We had a waiver of 47K MSL open til 8pm but made the call at 7pm, when we were putting it all together in a stack, that we didn't have time. Since Pete could only do a day trip, we agreed that the test launch would wait til next launch.

In hindsight. I think we actually did damn well to get within a couple of hours of flying a M to M (or 110% L), from idea, in less than four weeks (3 if you count that we all had a week off for different camps).

Yup, proud of the effort that went in from all involved, even you Erik!! :wink:

I may attempt to test the sustainer with a single stage flight tomorrow... or may not.
 
Well, sat here in the RV after the sun goes down, and I go to check the TeleMega and Telemetrum to see if I can work out why I was having problems connecting to them today.
Big DOH moment hit me. I had installed them on the sled when they had wire twigs. I then removed them, replaced the antenna with edge mount SMA, connected the new antenna and installed back on the sled. I needed to increase the clearance between sled and computer. When i screwed them back down, I put too much tension on the SMA and loosened the solder. Each time I moved the AV bays, the connection had been jiggling. Easy fix, but now i am REALLY glad we didnt fly.


330_5204.JPG
 
Last edited:
I am having some serious yen-ing for some carb..

Discussions were had, thoughts were exchanged, carbon tubing was purchased. I would like to get a couple of pieces, add strength to the area just above the motor, and to the AV bay. From looking through a load of videos, it seems that is the place where a lot of rockets seem to snap. This one even came with a couple of shots of auto gloss. Now it looks far to pretty to be a Vogon, unless it is part of the 'restraints' the wear as part of the uniform.

Worked more on the sustainer AV bay. Will update later with pic of that.

330_5212.jpg
 
Had to take a couple of weeks off for family, this last week we have been working the local faire helping the Rainbow Girls troup sell hot buttered corn on a stick to a captured redneck crowd.

Last week, I received a package from Aerotech. They were at our local large launch earlier this year and Gary was showing off the new HEI system that they have made. I have been negotiating (begging) with Charles from RCS to test the system in our upper stage and provide feedback.

So.... drum roll..... here it is....

330_5532.jpg 330_5535.jpg

330_5538.jpg 330_5541.jpg

330_5543.jpg

This is a floating head end closure which resembles the standard one, but, it has a glow plug initiator that screws into the top.

0


The initiator is available here https://www.rocketmotorparts.com/Low_Cost_Head_End_Initiator/p1577809_16501656.aspx

The idea is that you fill the glowplug end of the initiator with black powder, and seal it. When the system gets current, the glowplug glows, setting off the BP which causes a flame front to shoot down the inside of the closure (think a narrow version of smoke well, matching the core size of a normal grain). This then starts the grains etc. etc.


Now - to my comments on this.

When I saw it at the sat on a table at the launch i thought it was a real neat idea. We pawed it and ooh'd and aaah'd etc.

Now I have it in my grubby hands, I am starting to see a problem or two.

1 - the Initiator is $30, and it is a one use item.
2 - the lead to plug into the top of the initiator is a semi hard to find milspec item which costs about $40-60 ( but as you see, I found that a JST lead pops straight onto those two posts... score! )
3 - and this is the absolute deal breaker - there is nowhere to screw in an eyebolt for recover retention for minimum diameter.

hmm... so, we won't be able to use this, but, I will be passing on a few ideas that I have gleaned from other posts on this forum.

----

Update on the build.

Still working on HEI for the CTi load. If we use it in a snap ring case, with the hubcap system, then we 'should' be able to use our own HEI closure and tighten down the screws to get everything in place. Wont have upper smoke, but, will we see it at 50K??

Fixed the solder issues... still a slap on forehead moment.

Still working on getting myself happy enough with the motor / fincan retention on the upper stage. I have enough little worries at the back of my mind that I went and purchased the fully built Mongoose that was on the For Sale threads the other week. That has multiple CF tip to tip on the fins. Upper stage may change. We should still be able to MacGyver our electronics bay into it. Just thinking about that makes me happy. We will give that 'stage' the Barnards Star stickers...
https://www.rocketryforum.com/showt...-tip-to-tip-fin-can!!!!&highlight=mongoose+75

Lower stage interstage is being worked on, but all i am doing in that is making it so that there will be an external antenna on the AV bay. I am using 1/2 wave antennae that seem to be made of a 'memory metal'. I can wind the wire into a circle, hold it there for a minute, then let go and it springs back to fully extended. PERFECT!!!

---

Looking forward to my first trip to the playa, and really looking forward to meeting some of you guys.

If this all turns explodey, then at least I have proved worthy of Team Numb :lol::smile:
 

Attachments

  • 20170819_150046.jpg
    20170819_150046.jpg
    67 KB · Views: 90
Last edited:
Rocket changed a little.

I wasnt happy with the bottom section(s) of the airframe, and I wanted better motor retention, things were just bugging me.

So. new tube and reusing some old parts.
330_5685.JPG 330_5687.JPG

Tube is 60", almost exactly what the other three 'spare parts' tubes came to. One cut and we have an airframe. Move the Fisher fin can over to that.
The second pic shows what will be happening inside the airframe. Those two small coupler sections will be glued, or bolted, or both, in place. The bulkplate in between in a stepped double fiberglass plate. There is a hole in the middle of the plate which will hold an allthread, which will screw into the fore closure bulkhead of the motor. Lock nuts all over the place. It wont go anywhere. The bulkplate also has holes in it to allow the wires for hei to pass through. Above this will be a couple of couplers to double wall the area between the motor and the rear of the av bay coupler. I dont want it to snap either.

Thoughts??

3 weeks away!
 
Miracles they say can happen sometimes...

330_5688_resize.jpg 330_5690_resize.jpg 330_5691_resize.jpg 330_5692_resize.jpg

The CTi M840 with one spacer and our own HEI foreward closure in a 75/7600 case. Fits PERFECTLY.
 
Thanks Dan.. always glad to show it off. I can bring it up to your school if you wish, show the crowd, etc.

Ok. question for the hive mind (if anyone is still reading this after all the non rocketry blather...)

Sustainer is using a Fisher Fin Can (MaxQ). You can see pics through this thread.
There are exposed bolt heads, etc. at the fin root.

Do I do an epoxy fillet over them or not???

I know i dont NEED to.. but..
 
Sustainer is using a Fisher Fin Can (MaxQ). You can see pics through this thread.
There are exposed bolt heads, etc. at the fin root.

Do I do an epoxy fillet over them or not???


No, but you can swap the torx screws out for allen screws for a smaller drag profile. in addition, they are available in a slightly shorter length so you'll have less "stick out" on the backside.
 
so he hath spoke, so shall he be heard! No!

:wink:

Weights etc are getting more 'final' as the av bay is being upgraded to 11", the main chute has been upgraded, a fiberglass coupler going full length internal from case to av bay (stiffen it up), cameras, lipo for camera. Yup, just going over it again.

The beastie put on a little weight in the nose cone too for extra stability. I had simmed it with a 'standard' M840 upper stage, but, I am squishing it into a 7600 case, which is longer. Adding mass objects for the added length of case, all threads, etc, etc. yup, we put on weight.

So.. it looks like the sims now say around 75,000 ft and 2712 ft sec (Mach 2.5) ( with a 6 second butt clench )

I feel a little dissapointed losing 10K.. but.. I wanted this sustainer to be over 2.0 cal of stability when it went through MACH... it was at 1.5 earlier. I am happier that it will be more stable... and of course, losing a little speed wont hurt.

Now to see if the pocketbook can afford a 5 grain for the booster..

---

edit - heck, anything over 50K will be fantastic, amazing, awesome... full recovery is the main objective though, screw any altitude and speed losses.
 
Last edited:
well doh... entering numbers into sims at 1am is not recommended... you can put in the wrong numbers.

Things look better again. This is for weight without the side looking camera. Muvi 2K arriving Tuesday.
coast vs altitude.JPG
 
I can bring some stainless steel button head screws out to Sheridan with your decals.
 
Finally got to work on this a bit more, and I have a final setup. Everything fits... just.

The idea now is to have a complete double walled sustainer, solid from motor to nosecone.

So, we have a bulkplate that sits on the top of the motor case. There is a single spacer between it and the fore closure of the motor. An althread ties the two together, threading into the top of the closure.

On top of that is a small section of scrap coupler, just enough to be able to make a bay for my video camera. This, will click into the stepped bulkhead which is attached to the top of the motor. It will have a double stepped bulkplate at the top. These two connect together with 3 allthreads, which make a nice little case for the Muvi to sit in, and get cabletied in place with appropriate padding.

On top of this is another coupler section. This will house the shock cord for apogee.

Sitting directly on top of this coupler is.... the AV bay.

Solid from back to front.

The AV bay, and both of the other coupler pieces will be bolted in place with 3 bolts through the airframe and coupler, 120deg apart. Holes in the bulkplates allow for the wires for hei to pass through.

330_5713_resize.JPG 330_5714_resize.JPG

Hope the pic explains better than my words. There isnt one cc of spare space in this airframe.

Drill a few holes for the bolts, camera port and vents and we are done. Not going to do final fit or shear pins until we are on the playa and know how the fit there feels.

--

Feeling a lot better about this project now... it is as solid a rocket as i could think of... and it is light.

just a touch under 20lb with all recovery, etc in... but no motors; 45lb loaded

my definition of sucess on this project is that both stages light, in the correct order, at the correct time, and we get both airframes back..... everything else is gravy
 
I haven't got them covered.

Mike, if you have enough to spare, can you send out enough for my 4" fincan too. Just let me know how much.

Thanks!
Peter
 
retention bolts all in place, holes drilled, etc., and on a rail for 'in situ' fit. Looks like we have a rocket! (or two... the other is for 'fun')

Time to pack things up!

330_5735.JPG
 
I forgot to post pics of the finished bays.
You can see the motor case at the bottom, then there is a black bulkhead, the short coupler, another bullkhead and the larger coupler.
Each coupler is bolted in place with 6-32 bolts. The bottom bulkhead got two staggered rows of three, the top one got three. Same bolts will connect the AV bay to the external tube. (one bolt is not in place in the photo, the faint + sign above the hole is where I need to drill a 5/8 viewport for the camera.) The bolts are black oxide finish and look a lot like the Apogee style plastic rivets... but dont worry.. they are NOT!
There are a pair of 1/4 20 allthreads that connect the two bulkheads shown here, and another allthread that connects the bottom bulkhead and the fore closure of the motor.
You can see the black bulkhead and carbonite coupler of the av bay at the top of the stack.
The camera slots between the two allthreads and we will go caveman and zip tie it in place with a foam pad above and below it.
This feels solid, and as i said earlier, from the top of the motor case to the nosecone is double walled the whole way now!!

330_5740.JPG
 
Last edited:
Of course we need a sticker for the side of the rocket.... and my 10 year old asked me to put one of her keychains in the rocket. Deadpool! Guarantees success!

330_5705.JPG
 
Last edited:
I know you tested the Peregrine CO2 deployment system earlier, but have you done deployment testing on the completed/new configuration? Also, perhaps I missed it, but how are you managing deployment on the booster stage? BP charges?

Time runs short!

-e
 
Last edited:
Booster will have redundant charges for apogee. We will dump the main at apogee.

Yes I did tests on the other airframe, and thank you for reminding me. Tonight will be tests on this one. Since the amount of 'free air' space inside the airframe is nearly nothing, I am guessing that we shouldnt have a problem with separating the pieces.
 
In less than 72 hours, I should be on the playa with this beastie.
I have rambled a bit in this thread, which I have a tendancy to do, but, thank you to all who have shown an interest and especially Jim for pointing me the right way, Pete and Erik for letting me run with it :), Cameron Tinder for the Peregrine CO2, Charles Savoie at AT for the HEI to try and Mike for the real nice fins!
Now for packing up for the playa!! I am going to have fun nomatter the outcome!
 
Last edited:
You haven't rambled at all...your posts did, however, relay some of the flavour of HHGttG - I imagine Douglas Adams would have been proud. For those of us still on the lower rungs of the rocketry ladder looking on, this thread has been full of fascinating insights. Thanks for sharing, safe journey and all the very best for the flight. For those about to rock etc etc..
 
Great build. Have a great trip and flight. The weather was a bit wet a while ago, so don't forget your towel :wink:

“A towel, [The Hitchhiker's Guide to the Galaxy] says, is about the most massively useful thing an interstellar hitchhiker can have. Partly it has great practical value. You can wrap it around you for warmth as you bound across the cold moons of Jaglan Beta; you can lie on it on the brilliant marble-sanded beaches of Santraginus V, inhaling the heady sea vapors; you can sleep under it beneath the stars which shine so redly on the desert world of Kakrafoon; use it to sail a miniraft down the slow heavy River Moth; wet it for use in hand-to-hand-combat; wrap it round your head to ward off noxious fumes or avoid the gaze of the Ravenous Bugblatter Beast of Traal (such a mind-boggingly stupid animal, it assumes that if you can't see it, it can't see you); you can wave your towel in emergencies as a distress signal, and of course dry yourself off with it if it still seems to be clean enough.”
 
M840 glued and prebuilt
altimeters rechecked (sustainer main changed to 2000ft)
batteries checked and charged
solder rechecked (fixed)
antenna put on bulkhead for booster (i dont know how i forgot that i needed to do this... it was even written on the list)
fincan moved slightly and airframe tapped for setscrews
HEI bulkhead stripped and rebuilt with 3ft long ignitor wires
and a few other little things

need to repack rv a little, and throw all this stuff in the truck......

I am so glad I took the time to prep things...

oh... and KOA booked for tomorrow night coz i am not doing the straight through after a panicked late night. Feel much better now... and the KOA has showers for Thursday morn then off to Brunos for late breakfast.

See ya on the playa!
 
Back
Top