# Vogon Poetry - 2 stage - old thread

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#### Salvage-1

##### Certified
So... I haven't done a build thread in a while. I need to rectifly that!

I also have fallen in with rather bad company, they seem to egg me on and encourage my madness.

Just after NXRS this last weekend, someone got an itch to make another two stage. It all started with a name. Vogon Poetry. Which was a part of a joke as we were conversing online, but we love the name.

Since Vogons are a little on the ugly side, so this rocket has to be.. Ugly as... and we have to use what we have. No purchasing parts!
Scavenged around my garage for various parts, and, I think we have the start of the rocket.
Extra searching around the garage and out came a couple of motor cases... and something for the top stage, an M840 longburn.

So, booster looks like it will be a 4 or 5 grain 98mm Alumiflame, and the sustainer will be an M840 in a 75-7600 case.

Will update with pics, sims, etc. soon!:jaw:

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#### Tim51

##### Well-Known Member
I'll get my towel and get the pints in....this is going to be good. Subscribed!

##### Oddrocs Rule!
TRF Supporter
You must include that silly little lump of green putty you found under your armpit one morning. And please make sure all the correct model rocket forms are completely filled out. And not taking the time to travel just a light year to properly file them is no excuse!

No original or creative thinking allowed!

#### Salvage-1

##### Certified
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.

#### Salvage-1

##### Certified
... and now for some pics of the parts.

The booster will be 4" and will use a 4" Mike Fisher fincan mounted direct onto the motor case. Above that will be a length of tubing to hold chute, etc,. The electronics will be an RRC3 and a Telemetrum on the rear. The TeleMetrum will handle deployment and GPS tracking for booster, and RRC3 will do backup, as well as the staging charge. We wont be using that whole AV setup, just the sled, and one of the bulkheads. This will be built into the interstage. At the boosters apogee, the airframe will be separated at the lower bulkhead. The main will be secured to the bulkhead with a Tender Descender.
Above that will be the interstage, as yet to be built.
Then we have the sustainer. That nasty fincan will be on the bottom, then a length of tubing, notice, green tubing. We will let the front end of the motor stick out so we can do drogueless and zipperless. Above that, tubing, holding the AV bay, etc. Upper electronics will be Telemega to handle sustainer ignition, with an RRC3 as backup.
On top of all that is the nice green (notice a theme here) nosecone.

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##### Oddrocs Rule!
TRF Supporter
A dull gray or green cubic parachute would be nice. A green flame on the motor with lots of smoke. A paddle or two popping out somewhere would be appropriate. Are you going to read Vogon poetry before the launch? Any crabs to smash?

#### Tim51

##### Well-Known Member
... and now for some pics of the parts.

The booster will be 4" and will use a 4" Mike Fisher fincan mounted direct onto the motor case. Above that will be a length of tubing to hold chute, etc,. The electronics will be an RRC3 and a Telemetrum on the rear. The RRC will handle deployment and backup, as well as the staging charge. We wont be using that whole AV setup, just the sled, and one of the bulkheads. This will be built into the interstage. At the boosters apogee, the airframe will be separated at the lower bulkhead. The main will be secured to the bulkhead with a Tender Descender.
Above that will be the interstage, as yet to be built.
Then we have the sustainer. That nasty fincan will be on the bottom, then a length of tubing, notice, green tubing. We will let the front end of the motor stick out so we can do drogueless and zipperless. Above that, tubing, holding the AV bay, etc. Upper electronics will be Telemega to handle sustainer ignition, with an RRC3 as backup.
On top of all that is the nice green (notice a theme here) nosecone.
It's very generous of you to take the trouble to post these but I believe the plans for this rocket have been on display at the local Alpha Centauri office for quite some time, and quite frankly if Earthlings can't be bothered to go and look that's not your problem...

#### Salvage-1

##### Certified
hmmm old olive green mil chute...
green motor.. no thanks
Vogon Poetry... nah.. I prefer that of Paul Neil Milne Johnstone ( did you know that was actually a real author )

#### DavidMcCann

##### Well-Known Member
well my lack of noticing a spelling error sure killed the funny. carry on.

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#### jd2cylman

##### Still not Carl... ;-)
TRF Supporter

Well, you spelled it wrong... Vogon not Vorgon, silly. Try again and report back your findings.

#### dhbarr

##### Amateur Professional
But the dictionary was in a disused lavatory marked "Beware of Leopard"!

#### Salvage-1

##### Certified
Ok.. boss man changed plans already.. Seems he has a motor left over from a Keg project or something like that... so....

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#### JimJarvis50

##### Well-Known Member
If you want to know how high it will really go, try RasAero II.

A few years back, I flew a similar two-stager at AirFest (N2500 to M745). It simmed to 45K as I recall. Being a moron (to avoid breaking the waiver that is), I programmed the apogee deployment to fire at 45K if the rocket was still going up - just to be safe. That was the charge that did the trick, except that the rocket was still moving over Mach 1 at the time. Everything recovered in a heap. Later, the same rocket flew flew to over 70K at Balls. So much for RockSim and two-stagers.

Jim

#### Salvage-1

##### Certified
yup... completely agree.
When it comes to big stuff and Mach, I tend to start the build in RockSim, then go over to OpenRocket, then RASAero to work out Cd, then back to .... etc.. you get the idea.
It seems that this would hit around 65Kish... which is another reason that we are going to use the Altus Metrum stuff.
Well, the MAIN reason is that you can limit sustainer ignition if it is off vertical... that is why saved my pennies and bought the TeleMega.
I then bought a TeleMetrum because I love the data, etc, from the TeleMega, but didnt really want to lose $400 in an everyday rocket. NO.. dont hint at how much this will be 'risking' :wink: #### Steve Shannon ##### Well-Known Member TRF Supporter yup... completely agree. When it comes to big stuff and Mach, I tend to start the build in RockSim, then go over to OpenRocket, then RASAero to work out Cd, then back to .... etc.. you get the idea. It seems that this would hit around 65Kish... which is another reason that we are going to use the Altus Metrum stuff. Well, the MAIN reason is that you can limit sustainer ignition if it is off vertical... that is why saved my pennies and bought the TeleMega. I then bought a TeleMetrum because I love the data, etc, from the TeleMega, but didnt really want to lose$400 in an everyday rocket.
NO.. dont hint at how much this will be 'risking' :wink:
I'm curious what's gained by simming it in both RockSim and OpenRocket; what does one do that the other doesn't?

Steve Shannon

#### Bat-mite

##### Rocketeer in MD
I'm curious what's gained by simming it in both RockSim and OpenRocket; what does one do that the other doesn't?

Steve Shannon
One thing I have noticed is that you very often get different CP values.

#### djs

##### Well-Known Member
Ok.. boss man changed plans already.. Seems he has a motor left over from a Keg project or something like that... so....
How come it has cores larger on top than on the bottom? Isn't the other way around more recommended?

#### Salvage-1

##### Certified
Steve,
Rocksim doesn't seem to handle things above Mach 1.5 very well. For instance, I have a min diam 54mm Loki M project. Rocksim states something like 18K, which is stupidly wrong. Openrocket states 32K, and RASAero 31.5K
Also, Rocksim seems to calculate Cd on the higher side. I am testing out the TeleMega and TeleMetrum in another two stage (Wildman Jr 54mm airframe, 38mm to 38mm, with optional 54mm min diameter booster to swap). On the sustainer for that project, I have been playing with some ideas that use a coupler on the sustainer, that fits into a body tube on the interstage. The sustainer bottom end has a centering ring to close and 'space' and provide a flat rear end. Rocksim wants to say Cd is 0.67ish where RASAero says 0.57 I believe RASAero more than Rocksim.

Basically, each has its own plus'es and minus's. I run sims through them all, tweaking as I go. Then I seem to end up with a set of sane and rational numbers, which may be best 2 out of three results from all of the sims.

I'm curious what's gained by simming it in both RockSim and OpenRocket; what does one do that the other doesn't?

Steve Shannon

#### Salvage-1

##### Certified
How come it has cores larger on top than on the bottom? Isn't the other way around more recommended?
That is just how we threw in into Burnsim, yes, larger at bottom is how we will build it.

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#### Salvage-1

##### Certified
We are now on a timeline. Next launch at our club site at Brother in Oregon is in 4 weeks. We have call in waiver available to 44K, which will be enough to test this beastie.
Upper stage engine will be changed out to an AT M1297 with the new AT HEI system we may be getting to test. Faster sustainer but far less height. For this flight we will probably drop the Booster back down to a 4 grain. BALLS launch is still aimed at stupidly high.

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#### Steve Shannon

##### Well-Known Member
TRF Supporter
Steve,
Rocksim doesn't seem to handle things above Mach 1.5 very well. For instance, I have a min diam 54mm Loki M project. Rocksim states something like 18K, which is stupidly wrong. Openrocket states 32K, and RASAero 31.5K
Also, Rocksim seems to calculate Cd on the higher side. I am testing out the TeleMega and TeleMetrum in another two stage (Wildman Jr 54mm airframe, 38mm to 38mm, with optional 54mm min diameter booster to swap). On the sustainer for that project, I have been playing with some ideas that use a coupler on the sustainer, that fits into a body tube on the interstage. The sustainer bottom end has a centering ring to close and 'space' and provide a flat rear end. Rocksim wants to say Cd is 0.67ish where RASAero says 0.57 I believe RASAero more than Rocksim.

Basically, each has its own plus'es and minus's. I run sims through them all, tweaking as I go. Then I seem to end up with a set of sane and rational numbers, which may be best 2 out of three results from all of the sims.
Thanks. I understand the shortcomings for RockSim or Open Rocket, and I definitely agree with moving the model to RASAero. I would never rely on RockSim or Open Rocket for supersonic flights.
I don't see in your explanation anything to recommend RockSim, so why not just build the model in OpenRocket and skip the RockSim step? Or, what pluses does RS have?

Steve Shannon

#### Salvage-1

##### Certified
Creature of habit, and I paid for it
It is just my 'go to', almost a sketch pad.
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Scientist - Engineers explaination
Well, if we are using mean of standard experiments, we need an obviously 'very wrong' result to balance and qualify taking an average from the other two.

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#### Salvage-1

##### Certified
Boss man Pete just called around my house and picked up the pieces. I donated a 4" conical nose cone for the interstage.
This are going to go quiet for a week as he dissapears to the Oregon Country Fayre to become a hippy again.

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#### thequick

##### Well-Known Member
Just googled pics of oregon county fair. Way better than the vogon pics... (post 42. Win!)

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#### Steve Shannon

##### Well-Known Member
TRF Supporter
Creature of habit, and I paid for it
It is just my 'go to', almost a sketch pad.
-----------
edit
Scientist - Engineers explaination
Well, if we are using mean of standard experiments, we need an obviously 'very wrong' result to balance and qualify taking an average from the other two.

I can understand that!

#### Salvage-1

##### Certified
Ok... first things first. What is the most crucial part of the whole rocket... yup... at the back of the class... yes???
"the Interstage, Sir"
Correct, you may continue eating that slug.

My thoughts are that the Interstage is the most crucial part. If IT fails, it doesnt matter what either of the other two parts does (the ones with fins and big flame producing stuff)
We need this strong and stiff, no movement from either stage when it is flight.. C'mon its gonna have a 50% N kicking it in the ass. That is like hitting a brick wall on your motorcycle. Nope, nothing needs to move... keep it all in a straight line.

In the sketchup, I have omitted about half of the centering rings. There will be wooden spacers between the centering rings, and the whole setup is locked together 6 with 8-32 allthreads. Then the bottom fiberglass body tube will be bolted onto the rear of the interstage. The booster stage will split in the middle.

Yup, bonus points for noticing that sketch was from OpenRocket. I like the ability to do offsets, etc with components, looks pretty.

#### Salvage-1

##### Certified
Vogons in Wikipedia
https://en.wikipedia.org/wiki/Vogon

Vogon Background (from the Animated Serial)

Vogon Poetry (from Original BBC TV Serial)

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#### Salvage-1

##### Certified
Poetry example..

Oh freddled gruntbuggly,

Thy micturations are to me,

As plurdled gabbleblotchits,

On a lurgid bee,

That mordiously hath blurted out,

Its earted jurtles,

Into a rancid festering confectious organ squealer.

Now the jurpling slayjid agrocrustles,

Are slurping hagrilly up the axlegrurts,
And living glupules frart and stipulate,

Like jowling meated liverslime,
Groop, I implore thee, my foonting turlingdromes,

And hooptiously drangle me,
With crinkly bindlewurdles,
Or else I shall rend thee in the gobberwarts with my blurglecruncheon,
See if I don't!

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#### RocketFeller

##### Well-Known Member
Three weeks? You have a lot of work to do!

I wanted to get you over to show me how to do the awning on the new RV, but I guess I may have to resort to YouTube.