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HMS Sophia
Post subject: Rocketry and so on.Posted: August 10th, 2015, 8:55 am
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So, I'm writing this series of novella's for release and as part of it I'm producing pixel art drawings of various involved vehicles. So, here you go, the three rockets seen in the first novella that should be out in the next month or so.
[ img ]


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eswube
Post subject: Re: Rocketry and so on.Posted: August 10th, 2015, 7:40 pm
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Nice start. But I have a feeling that more work possibly could be put into shading and detailing.


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HMS Sophia
Post subject: Re: Rocketry and so on.Posted: August 10th, 2015, 7:45 pm
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eswube wrote:
Nice start. But I have a feeling that more work possibly could be put into shading and detailing.
Quite assuredly :)


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HMS Sophia
Post subject: Re: Rocketry and so on.Posted: August 11th, 2015, 1:41 pm
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And... updated:
[ img ]
I'm really uncertain on the guidance fins on the big Aggregat rocket. I might edit them at some point. Otherwise, details added, shading done, I acknowledged the american urge to put their name on everything... :P


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Tobius
Post subject: Re: Rocketry and so on.Posted: August 11th, 2015, 2:54 pm
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Now this I know! The R-6 will have sever vibration problems at launch. That payload as fared will oscillate as an inverted pendulum.

I hope this helps. It's called Astronautica and is a quick source for rocketry on the web.

The German rocket looks quite good. Are those supposed to be gimbaled engines? The Germans historically used exhaust nozzle vane steering and aerodynamic fins and eschewed gimballing as too heavy, complex and failure prone. It was the Americans who used gimbaled engines.


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HMS Sophia
Post subject: Re: Rocketry and so on.Posted: August 11th, 2015, 3:19 pm
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Tobius wrote:
Now this I know! The R-6 will have sever vibration problems at launch. That payload as fared will oscillate as an inverted pendulum.
Why will it suffer vibration issues? It's not exactly subtly a knock-off of the R-7. And only the upper cone of the supper section is fairing, the rest is, as with the R-7, fuel for the core booster.
Tobius wrote:
The German rocket looks quite good. Are those supposed to be gimbaled engines? The Germans historically used exhaust nozzle vane steering and aerodynamic fins and eschewed gimballing as too heavy, complex and failure prone. It was the Americans who used gimbaled engines.
Yeah, essentially. We're 20 years past the original design of the A-4 here, so we're a bit more developed than initially, and I think with only single axis gimballing (yay for having four engines) we'll save enough mass for it. I wanted to avoid carbon vane steering.


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Tobius
Post subject: Re: Rocketry and so on.Posted: August 11th, 2015, 8:03 pm
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The way the payload is fared back into the second stage and the exposed tips of the strapons will set up a mutually interfering series of shock waves. Oscillation sets in and your rocket breaks up before max-q. You get a nice fireball in the sky and debris everywhere. The Russians lost a lot of people learning that the hard way.

The Germans never, repeat never, like to use gimbals down to the present. The French and Americans do; the Russians sometimes. (Depends on the designer.). Mixed staging rockets (solids and liquids) tend to avoid gimbal engines in strap on stacks for obvious reasons. Agena, Delta and Titan stacks are some exceptions as is Ariane, but in so doing the engineers made extremely sure that restricters were in place to keep those liquid fueled engines' exhaust plumes well away from the solid fuel candles' exhaust plumes. The Americans lost a couple of Titans that way.

What's wrong with carbon vane steering? It works rather well and it's cheap.


Last edited by Tobius on August 11th, 2015, 9:26 pm, edited 1 time in total.

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HMS Sophia
Post subject: Re: Rocketry and so on.Posted: August 11th, 2015, 8:10 pm
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Tobius wrote:
The way the payload is fared back into the second stage and the exposed tips of the strapons
But.. it's not? Faired back into the second stage, I mean. The core booster burns from launch to orbit, just like the R-7. The fairing is the nose cone and thats it.
I'll take a look at the booster tips.
Tobius wrote:
What's wrong with carbon vane steering? It works rather well and it's cheap.
Fair enough (and to everything I snipped for length). I'll look at adding them :)


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Tobius
Post subject: Re: Rocketry and so on.Posted: August 11th, 2015, 9:22 pm
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You may not be seeing it, the rocket three dimensionally as a stack.

Try this. Maybe it will help my explanation if you see an R-7 function.

I would point out, that the Russians (who are no slouches when it comes to rockets) use pairs and fours with their strap-ons. The Americans think they can wrap 5-7-9 candles around a Delta and get away with it, but even they do not use the 3 strap-on configuration. It's actually too dangerous if one of the strapons fails or burns un-even.


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HMS Sophia
Post subject: Re: Rocketry and so on.Posted: August 11th, 2015, 10:16 pm
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Tobius wrote:
You may not be seeing it, the rocket three dimensionally as a stack.

Try this. Maybe it will help my explanation if you see an R-7 function.
I'm still unsure of your point. Yes, later developments of the R-7 had an upper stage (and even several) after the core burned out. The original, and the Semyorka which launched Sputnik 1, did not.
I'd be grateful if you explained again.
Tobius wrote:
I would point out, that the Russians (who are no slouches when it comes to rockets) use pairs and fours with their strap-ons. The Americans think they can wrap 5-7-9 candles around a Delta and get away with it, but even they do not use the 3 strap-on configuration. It's actually too dangerous if one of the strapons fails or burns un-even.
Fair, but it's the same with any double booster configuration as well (such as, say, Titan). An uneven burn is always incredibly dangerous to a launches chance of success. I would argue that a tri-booster set up may be more dangerous, but not that it is too dangerous.

It does make me wonder about switching to four for a crewed booster though...


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