DoctorEvo
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Posts posted by DoctorEvo
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Ironically, the American skill in miniaturisation was partially due to being unable to match Soviet rockets for sheer brute force. The difference in size between Sputnik 1 and the first Satellite that the Americans attempted to launch (Vanguard) was striking - Sputnik 1 was orders of magnitude larger.
ONE order of magnitude, if that.
And that was because the Russians lauched Sputnik from a modified R-7 ICBM (the very same rocket Soyuz is based on), while the American scientists wanted to use rockets designed for scientific purposes (i.e. puny little sounding rockets) to accomplish the feat. Although, the Americans were at somewhat stagnant at that point, with Von Braun stuck on his Redstone design and nobody else bothering to design new and revolutionary liquid-engines like Glushko was. So yes, in a sense, the American rocket program WAS unable to match the Soviets until Sputnik gave 'em a swift kick in the rear.
Then the almighty ATLAS brought America up to a competitive level with the Russians, in terms of rocket technology at least.
One thing that I have always found ironic: the Soviet moon program fell victim to the fact that multiple bureaus were working on multiple projects, often developing nearly identical hardware without any communication with others. The Soviet system was centralised.
The Soviet moon project failed because Korolev and Glushko couldn't get along.
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Riiiiiight...
WHAT effect am I looking for, exactly? As far as I can tell, it's not doing anything unusual.
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*looks at all the controls*
No matter how much training NASA could give me,
I would never be able to fly that thing.
Looked pretty reasonable to me, until I saw the overhead switch panel. ??? Snap your neck just trying to SEE half those switches.
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Faux News is not a legitimate press service.
BBC and Al Jazeera English are the only old-media that I trust on world news anymore.
Just getting the thing into near-space and then getting it hyper-sonic is a HUGE accomplishment. Since almost nothing has traveled at hyper-sonic speeds in atmosphere they are doing fine for such unknown territory.
OMG SO REVOLUTIONARY
THERE'S NO WAY THEY COULD'VE DONE ANYTHING LIKE THIS BACK IN THE '60s-ohwait...
http://en.wikipedia.org/wiki/ASSET_%28spaceplane%29
http://en.wikipedia.org/wiki/X-23_PRIME
Just think how powerful of a system they are creating. If the vehicle is sitting and waiting it can be to any point on Earth in about an hour or less. Pack a warhead on the thing and fly it into the target you can blow up an enemy nuke as they are prepping it for launch.
Yeah, I guess. I dunno how useful the thing'd actually be, but I will admit it's pretty frickin' cool.
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the rocket I'm working on for auto-orbiting looks very similar to that. Then again I imagine simple rockets would work best with the approach of using a gravity turn.
This rocket is about average complexity for me. It uses SASs, which the majority of my designs do not, but it is only two stages. The absence of complicated staging sequences certainly simplifies things.
Overall, for a good gravity turn, all you need is decent positive aerodynamic stability (which this rocket stage only has until the first tank empties, but by then it's outside the atmosphere, so that's good enough) and a good, intermediate acceleration (i.e. moderate amount of thrust). From there, it's all just about managing a proper entry - and this is the part I'm still perfecting. My first stage performs great, tracking at a slight 4-5 degree angle under SAS control, right until burnout at 15.5 km, at which point I stage immediately and wait for a target velocity to fire the engine. That last attempt was at about 92 m/s, but we're talking a fraction of a second opportunity to light the motor and get it right. If I do it, there's no way I'll be able to do it consistently, and it's certainly not completely automatic by any measure.
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It's silly. This test vehicle was intended to crash into the water anyway, after it's flight.
My thoughts exactly.
The press making a big deal out of nothing, as usual. :-\
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You can actually perform some interesting shenanigans with winglets.
That you can.
For starters, the two different kinds of winglets have differing masses (one is 0.03, one is 0.04, if I recall correctly) and different drag profiles. This means that even when arranged exactly symmetrically, you can shift a rocket's CoG slightly.
Their drag values are the same (0.5). Their LIFT values are not.
What's more interesting, though, is that you can in fact get the winglets to cause rotation in the winglet's plane. Simply place one a bit further forward than the other. The difference in where the drag is applied will create a torque. Unfortunately, this is such a minor effect that it is easily overwhelmed by other influences and therefore not practical.
There's no reason why this should work. Many a high-performance sailplane use arrangements which place one wing a few inches in front of the other, to no ill-effect. The net lift shouldn't have any imbalance left and right.
Me, I've been working on doing this as 'throttle-to-max, hit space, achieve orbit' challenge, but SAS appears to be a necessity, which is going to mean more inputs. =(
You mean I have competition?
It's on, broski.
*edit*
SO FRIGGIN CLOSE
2,568,351 meters of ground covered... gotta be near 2/3 of the way around. I've got the velocity, it's just fine-tuning the attitude I ignite at...
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How do you stop boosters from overheating?
I dunno... I just built the rocket, and tested it, and every stage ran out of fuel before exploding, so I left it the way it was. I think the struts help to dissipate the heat.
...and why does a ship with one booster and one decoupler fly higher (by not overheating) than a ship with just one booster?
All non-engine parts dissipate heat from whatever engines they're near.
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so in your expert opinion
will boosters only take you so far...?
Decidedly not. By Goddard's shiny bald head, I declare that, provided a sufficient quantity of them, they will take you to the end of the universe.
and
are haters gonna hate?
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I still don't understand this obsession with huge rockets. Beyond a certain point, adding more mass hurts you.
But... if you put another rocket on your humongous rocket... and if THAT rocket has a rocket on it... I mean, the possibilities are ENDLESS!!
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*golf clap
i am quite impressed
only thing left is to leave the death grip of the planet
NOT ANYMORE!!
Meet PROBEwster; so-named due to it's aesthetic and mission similarities to the Luna-E3 that 'Probe' is modeled after.
Presently on an escape trajectory, never to return to Kearth.
So I guess this conclusively proves Timmy wrong...
Boosters can get you ANYWHERE.
(I'm sure Jeb is thrilled by the news.)
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Foamyesque and I have both achieved this; Foamyesque was the first, with this monstrosity (and I mean that in the most affectionate way):
And I later managed it with this:
Given the antenna-like struts sticking out of my final stage, I am hereby retroactively renaming my rocket 'SRButnik.'
Anywho, I don't believe anybody's achieved escape velocity yet using nothing but boosters. I'm certain it's possible, though...
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As a matter of fact, I think a high center of gravity might help with drag instability as well (the dart effect?)
Indeed. If you roll back a few pages, you'll see that I brought this up already.
Of course, in most cases shifting the CG may also shift the center of pressure, so if you shift the CoP FURTHER forward than you shift the CG, you will only destabilize the rocket. If your rocket is built entirely of LFTs and LFEs (i.e. high density, high ballistic coefficient), some SRBs would be better off placed near the bottom as their drag will be more influential than their weight. However, a rocket with several winglets would certainly benefit from forward-mounted SRBs.
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You need to basically transport a 3 tank rocket into orbit and back down. From the ground, 3 tanks are enough to achieve orbit and return under a powered landing.
That was my plan exactly. My 'Barracuda,' as I named my design, was just barely not up to the task, even after I wrapped it in three stages of SRBs. Back to the drawing board, I suppose.
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i Have run a few test and have to say that the effectiveness of a Gravity Turn depends on the rocket.
If you got a nice slim rocket without any boosters strapped to it, the Gravity turn works nicely. As soon as you have thrust that is not centered however the rocket turns so rapidly that you crash back to the launch pad. In that case you need the SAS to fight the wobble. But once you're over 10km you can turn off the SAS and the gravity turn does the rest.
You still need SAS on a symmetrical rocket. Even the SLIGHTEST disturbance at launch will cause the gravity turn to occur much too soon, and you will inevitably crash.
I used a 2-stage arrangement because that meant I could 'turn off' the SAS at about 130km by simply staging and still be following the rules of the challenge. The top stage, without the SAS on it, performs the gravity turn just fine.
Oh yeah, and winglets. They help.
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I heard about this thing. They're planning to turn it into a cruise-missile with worldwide range. They like the idea because it can glide as far as a ballistic missile goes (well, almost), but it doesn't look enough like an ICBM to scare other countries into launching their nukes.
And the $320M is the total program cost, not that of a single vehicle. If you're paying $320 million for a missile, it BETTER be able to carry nukes halfway around the world.
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You just reminded me that in Soviet Russia, everything is backwards and upside down.
Oh, and they explode you (instead of the Kerbals).
You gotta admit, those early Russian rocket scientists deserve some respect. Tsiolkovsky, Korolev, Glushko, ALL seemed to have an edge over their Western counterparts. Back in the early '30s, Russian rocket technology was YEARS ahead of anyone else's, INCLUDING the Germans'. Then many of those brilliant minds fell victim to Stalin's purges, and progress completely halted. I'm of the belief that, if Korolev & gang hadn't been locked up, they would've been bombarding Penemunde with ballistic missiles quicker than Von Braun could even blink.
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You can have a SRB stage firing radially from just one engine, giving asymmetric thrust and tilting the rocket. Or you can just carry an asymmetry in the rocket that makes it tilt slightly (but not too much).
Bad idea.
I tried it by mounting just ONE winglet on the side of the rocket, and even that was too much.
For the most part, you don't need to force your rocket to arc over - even the SLIGHTEST disturbance will be enough to make the rocket arc over on it's own, simply due to the pull of gravity.
http://en.wikipedia.org/wiki/Gravity_turn
Also, it's interesting to note that, if properly executed, this is actually the most efficient way to get a normal rocket to orbit.
Though, the simplest possible orbiter is just a 3 tank rocket (no parachute or SAS). It will slowly tilt by itself and reach near horizontal velocity just about when it runs out of fuel.
That will still tilt over too quickly. Using a two-stage arrangement with an SAS in the first stage (NOT in the second stage) works well for boosting your upper stage with enough velocity so that you can make a nice, gentle, well-timed gravity turn after you drop the first stage. The SAS fights the gravity turn, but once you drop it, your second stage will simply arc over with gravity on it's own (if it's stable, that is); all YOU have to do is pick the right moment to fire the engine and it should be nearly level when you run out of propellant.
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So I'm allowed to control staging myself?
...I think I can pull it off. Still far from 'automatic' though - carefully-timed staging and ignition can give you a surprising amount of control over a well-designed rocket.
*edit*
Major progress made, but I haven't succeeded just yet. I built a nice, stable 2STO rocket, and after a few iterations (adding another tank to the upper stage; adding winglets to both stages; and adding an SAS to the lower stage), I seem to be nearly there. I've finally got my flight profile nailed down though: throttle to 95-100%, turn on stability augmentation, ascend at a slight angle (under full SAS control) to ~14 km on first stage and jettison immediately; wait 5-12 seconds as the upper stage arcs down to about 75 degrees pitch, and fire upper stage. It is at about 26 km and 1500 m/s that I run into trouble; the fuel burning from the front tank makes the upper stage unstable and it quits arcing towards the horizon, then flips over into a nose-up attitude until about 65 km and 2500 m/s (still going up too steeply for a stable orbit). More inert noseweight is probably needed, but I'm gonna call it a night right now.
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Damn you're good. I went back and checked, and it was indeed the RL-10
Lucky guess, maybe? ;D
It's a VERY common American turbopump-driven, liquid fuel engine, and it's about as prolific in US aerospace history as the trusty old RD-107 was for the Soviets. Plus, it looked to be about the right size, dimensions, and vintage.
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Wow, this is friggin' hard.
One question; are we allowed to use a LFE for our deorbit burn and save the SRB for terminal guidance?
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I'll redo these later with properly built rockets so that nothing changes but the point of thrust, and then we'll see what actually happens.
If you move the engines, you'll be moving the CG as well, causing a change in stability. In THIS sense, certain rockets CAN benefit from having the engines moved up to the front (as I already mentioned), but it is not because you are moving the thrust so much as moving the weight of the engines.
The only way to test this properly would be to put engines at the top AND bottom of a rocket, and then fiddle with the staging so that you can test it with ONLY the top engines or ONLY the bottom engines firing. Also this test would best be done quickly, before significant fuel burn affects the center-of-gravity.
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Actually, as a note, you'll find that very few airplanes actually fly at a zero alpha, at least in their cruise configurations.
'Zero' alpha is merely an arbitrarily-picked reference angle. If the engineers want it to be at the zero-lift axis, they'll put it there. But in the real world, you'll find this is quite often not the case, and they often WILL place 'zero' along the cruising AOA (for instance, this is the way I set up my Dynon primary flight display in my RV-6).
Jetliners, as a rule, are designed to fly about 3-5 degrees nose up in cruise, because it's a more fuel-efficient configuration (closer to maximum lift:drag ratio) than flying nose-level. Smaller aircraft, too, tend to have at least a slight nose-high attitude in cruise, because deflection lift is, honestly, the most important contribution to an airplane's lift; airfoil lift is not really enough to get off the ground by itself, no matter how much you've heard people throw Bernoulli's Principle around.
Well put.
But it's worth noting that the angle you're talking about NOW is another arbitrary reference-angle picked this time by the airfoil designer. It is most often the same as the chord line by convention, rather than the cruise attitude (which the airfoil designer couldn't possibly know unless it was given to him) or the zero-lift axis (which he WOULD know). In the case of symmetrical airfoils (like the ones most likely to be modeled in KSP), however, the zero-lift axis IS in fact the same as the chord line, which permits a number of simplifications.
'Then why,' I hear you cry, 'don't I find myself climbing a hill to go to the lavatory on an airliner?' That's because the designers, knowing that passengers would find a cabin that's got a significant pitch attitude in cruise rather uncomfortable, will mount the wings so they're not actually parallel with the cabin floor. If an airplane is designed for a three degree nose-up attitude in cruise, they may design it with the cabin floor being pitched *down* 1.5 degrees in a wings-level configuration, both making it more comfortable for passengers and giving the pilot better visibility over the nose on approach. It's the same trick as some early rocket designers used to spin-stabilize their rockets by having the fins slightly canted off the vertical, essentially.Well, if you're going to go THAT in-depth, then you might as well tell them what this angle is called...
http://en.wikipedia.org/wiki/Angle_of_incidence
(I wonder if Peter Garrison ever did sketch out that light airplane with 2x12s as wings, like he always joked one could do with the amount of engine power now available...)
BRB, looking up wind-tunnel data on a 2x12 rectangular section @ Re = 1000000...
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This sounds like fun.
Can I put frickin' laser beams on mine?
Challenge: Drag race to 100KM altitude
in KSP1 Challenges & Mission ideas
Posted
I find your lack of booster disturbing.