TheEpicSquared
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Posts posted by TheEpicSquared
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For your 4-core sustainer, don't you mean that AD or BC can shut down, and the thrust vector would be in the same place?
And about the staging, I guess it depends on the numbers. It seems reasonable. Maybe have the 8 boosters as the primary thrust source for initial ascent, with the sustainer core at half throttle (having four cores means that they could be differentially throttled for control). When the strap-ons separate the sustainer would throttle back up to full power, until burnout and separation. One of the strap-ons should work as a kick stage for final orbital insertion. However, the TWR might be a bit over-the-top.
In this configuration, I doubt we would be able to recover the 4-core sustainer though, seeing as its being accelerated to nearly orbital velocities. We could recover the SRBs, but the sustainer is by far the most expensive, it seems.
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I think that before going any further, we need to decide on the staging. After all, parallel and Arian stages rocket do work differently. Will we use parallel or serial staging? Both? If serial, 2 or 3 stage design? Have both parallel and serial, like Falcon Heavy? IMO we need to get that sorted before we go any further.
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@sevenperforce Gasoline and petrol are the same thing, so I don't see why it wouldn't work with jellied petrol. And that's another problem solved! And with the air-start problem solved, I once again think serial staging is better. It also allows for modularity: there is enough space in the first stage to add SRBs or even common cores, to increase payload capacity.
Now that I think of it, my mechanical separation idea does have some drawbacks. I think a pneumatic/hydraulic pusher system to push the second stage away from the first stage would be best, using the monopropelant HTP.
On another note, how exactly are first and second stages connected? I'm assuming it uses explosive bolts that disconnect at separation or something, but I don't know exactly.
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@sevenperforce That's quite an interesting idea. There are some limitations, like @qzgy said, but those seem work-around-able. How would it be ignited though? An ignition plug at the bottom of the HTP tank would be subject to extremely high temperatures.
Would electric spark ignition work? Two wires with a battery (doesn't have to be big, maybe could be as small as an AAA) at a point of lower stresses, and the wires would contact each other in a way that would produce a spark when the circuit is completed. At the very least, this would eventually heat up the metal (and plastic insulation) of the wire, and could possibly ignite the propellant.
And another thing, how would separation of the strap-ons work? You could use explosive bolts, but that involves even more complex events. One idea I had is as follows:
So you have a "claw" of sorts, attached to the center core, which holds on to a rod that is attached to the strap-on. Between these two "claw" arms is a very compressed spring, attached another to the center core. The idea is that when its time for separation, the "claw" opens, releasing the booster. This allows the spring to push the spent booster away from the center core. Combined with a separation motor at the top, this theoretically should allow for strap-on separation without the need for explosive bolts.
I drew a quick diagram (the separation system and the stages are not to scar relative to each other, of course)
Obviously, the "claw" arms, the attachment point, and the rod hat connects to the strap-on would have to be incredibly strong to withstand the forces of launch. In the diagram, I only drew two arms, but in reality 4 or 6 or even 8 (or more) would be better, as it would hold the rod from every angle.
Thoughts?
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It's a bit ambitious, I know, but I really think we might be on to something here. IMO, we should settle on an idea (right now I like @sevenperforce's HTP+napalm idea) and start designing.
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I have noticed that SpaceX hasn't published the webcast of the Intelsat mission yet. Makes me wonder if it's a technical issue with YouTube rather than an issue on SpaceX's side. Then again, if that were the case, SpaceX could have just published it somewhere else...
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6 minutes ago, sevenperforce said:
I don't think the individual cores would be larger than a serial first stage. Falcon Heavy could still take a reasonable amount of payload to orbit even without its upper stage, and its cores are the same size as the F9 first stage. And here we'd be dealing with three boosters instead of two.
That being said, a kick stage (maybe made from a cluster of separation motors) for the final push into orbit is still probably a good idea.
Fair point. However, a kick stage would resurface the problem of air-ignitions, which we were trying to avoid by using parallel staging. I guess it's impossible robber rid of completely. You'd still need to light the separation motors in the air.
6 minutes ago, sevenperforce said:If we were dealing with low-energy propellants, fins might work...but with medium-energy propellants like HTP and jellied petrol, specific impulse is high enough that you'd run out of aerodynamic control authority before the boosters ran out of propellant. And the vanes are a REALLY complex metallurgical problem.
RCS allows replication of the HTP injection system and allows attitude control even while the engine is off.
Yeah, I agree that jet vanes would be hard to produce, seeing that it would have to withstand huge temperatures and all of that. I guess differential throttling is the way to go, if it's precise enough.
Another possibility for first stage control (could be complicated though) is secondary injection thrust vector control, which is injecting a liquid from separate tank into the nozzle of the boosters, thus producing more thrust on one side, causing the rocket to rip over the other way. The PSLV uses it for lower stage control, but as I said, this system would be relatively complex. Differential throttling seems much more attractive.
I'm not disputing the addition of an RCS system. It's definitely necessary. I just don't think it should be part of the payload, it should be part of the rocket itself. And I don't see why HTP wouldn't work.
17 minutes ago, sevenperforce said:LOX is definitely higher-isp, but it is harshly cryogenic and eats anything it touches. It's also not self-pressurizing since it isn't a monopropellant like HTP. Finally, since the impulse density of jellied petrol is lower than most hybrid rockets, the higher impulse density of HTP helps. You can also synthesize HTP yourself...can't do that with LOX, not in any significant quantities.
Good point.
12 minutes ago, qzgy said:For at least lower stage attitude control, have vernier thrusters been considered? Something like on the R-7 family?
It might add unnecessary weight, cause an integrated RCS system might, if good enough, be able to already perform this job.
Verniers only would work effectively on liquid fuel engines, whereas the rocket @sevenperforce and I are discussing would be hybrid.
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21 hours ago, sevenperforce said:
A hybrid rocket addresses both of these problems, actually. Hybrids are throttleable because you can control the flow of the oxidizer. And since hybrids are pressure-fed by definition, they are already going to be built much stronger than the liquid stages we are typically used to, with plenty of margin.
Oh, well that's the structural problem solved then.
21 hours ago, sevenperforce said:I'm thinking a 4-core arrangement, with three strap-on boosters around a central core and the payload mounted on top. Each of the strap-on boosters would be fitted with a single tailfin for passive aerodynamic stability and roll cancellation on ascent, and they could be differentially throttled for yaw and pitch control. All would ignite and fire at full throttle on the pad, but the core would throttle down shortly before Max-Q and remain throttled down until booster burnout (similar to a Delta IV Heavy). At booster burnout, they would separate and the core would be throttled back up.
The payload could be fitted with a simple HTP monoprop RCS system, providing guidance for the core during the terminal portion of the burn. It would also probably make sense to give the payload a small COTS solid-fueled kick stage for final circularization.
Alright, but even with throttling the center core down after liftoff, it would still have to be bigger than a serial staging first stage. However, if an amateur team can fabricate a stage big enough, then I don't see why it wouldn't work.
However, I think the fins on the three boosters should be actively controlled, seems like it would be more precise than differential throttling. Also, if the core stage had jet vanes, that could do away with a monoprop RCS system on the payload, and instead have it on the stage for control while coasting. This would give more flexibility to payload as well.
21 hours ago, sevenperforce said:Hybrid casings have to be strong enough to hold combustion pressures, so they are plenty strong enough to survive being chuted down. Since all four cores are essentially identical, this makes the testing process much simpler since they would be readily reusable.
One cool addition would be an ablative nozzle that reshapes over the course of the burn. It could be machined out of something as simple as ordinary wood (cork, pine, or oak) and allow the nozzle expansion ratio to increase to compensate for change in pressure and thus maximize specific impulse.
I'm assuming that only the three boosters would be recovered, as the core would get all the way to orbit. But yeah, drogues and main chutes could fit in the nosecones of the boosters.
Speaking of the boosters, I'm assuming a separation motor would be needed at the top to push away the spent core. That seems relatively easy, however, to accomplish. This would, however, require additional heat shielding on the core where the separation motor plume would hit the core.
The ablative nozzle idea is interesting. It would need a lot of testing, but if it can be done by amateurs, then it could be quite beneficial.
23 hours ago, sevenperforce said:Solid oxidizers have much lower specific impulse than liquid oxidizers, so that's one of the issues there. That's the biggest reason why solid-fueled rockets have notoriously low specific impulse: solid oxidizers have high density and low specific energy. And the solid oxidizers that do exist do not vaporize well at all, in comparison to hydrocarbon-based solid fuels which vaporize, mix, and burn readily.
Well, that's probably why reverse hybrids aren't used widely. So I guess standard hybrids are the way to go. Which brings me to my next question, which would be the better oxidizer for jellied petrol, HTP or LOX? I'm assuming the one which results in a higher Isp would be the one to go with.
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4 minutes ago, Scotius said:
Wonder why they haven't released it yet? That must have been the most badass landing ever
"Hey, look - our stuff can recover even from such seemingly hopeless situation. Aren't we awesome?" 
Oh, the suspense... release something! Anything!
(of course, I'm talking about the BulgariaSat-1 landing, but Falcon Heavy details wouldn't hurt either...)
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21 hours ago, SQUAD said:
the camera would madly flicker up and down after you crash a vessel into the ground
About time
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8,589,934,592
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On 7/6/2017 at 3:15 PM, sevenperforce said:
The advantages of parallel staging seem dramatic, if you can pull it off. Stage separation is a very dicey maneuver, and doing an air-start of the upper stage engine is an added complication. Parallel staging allows you to use common cores (meaning less testing) and ground ignitions.
Here's a thought. What about a hybrid/vapor pressure-fed rocket using catalyzed HTP as the oxidizer and autogenous pressurant (perhaps with liquid nitrogen as an auxiliary coolant) and jellied petrol as the fuel? The biggest problem with hybrid rockets is getting an even burn surface (combining liquids and solids is hard), but napalm would flow and vaporize rapidly enough that this wouldn't be an issue, and the HTP would decompose and vaporize so you wouldn't have liquid-on-solid at any point. If the napalm used aluminum salts as a gelling agent, you could easily get upwards of 260 seconds of isp. While both napalm and HTP are extraordinarily dangerous, they are well-studied and present no particularly exotic handling requirements. HTP can be manufactured with a fairly inexpensive lab setup and petrol is, of course, widely available. If the rocket was equipped with chutes and peroxide-charged (or nitrogen-charged) airbags, it could be easily recovered and refueled much more simply than typical hybrid rockets, since napalm pours readily.
An alternate option would be to add a powdered oxidizer to the fuel in very low quantities, so the solid/gel fuel would burn on its own. This would ensure a consistent burn but still allow for partial throttling like a typical hybrid.
Idk about parallel staging. I can see the advantages of ground ignition, but if a stage is being lit at sea level and is meant to get to orbit, it seems that the stage would have to be quite large to accommodate the propellant burned. which would be difficult for an "amateur" (relatively speaking, of course). This could be avoided by having a throttleable liquid engine, but manufacturing a liquid-fueled engine would be vastly more complex and expensive than a solid or hybrid.
Also, parallel staging would mean the center core would need to be significantly strengthened, which would be yet another added complication to worry about. Good example of this is the Falcon Heavy.
Provided that napalm could be obtained, and HTP could be produced in adequate amounts, I like your idea for a hybrid. I can see how jelly would allow for more contact between the oxidizer and the fuel.
Another thing that I'm wondering about for a hybrid: reverse hybrids. Having a liquid fuel and a solid oxidizer instead of the other way around. There isn't a lot of information on the web, but immediately I can see a few advantages. I think the biggest is that you could do away with toxic/poisonous liquid oxidizers like HTP or nitric acid, and the problems of cryogenics like LOX. You could use fuels like petrol, which is widely available and much easier to work with. A standard solid oxidizer like ammonium perchlorate could be used, but I'm not sure how available that would be. Probably quite expensive though, because military and all that.
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8 minutes ago, Phineas Freak said:
It is part of the "Cryotanks" mod:
GameData\CryoTanks\Plugins\SimpleBoiloff.dll
Did you have any luck by just installing the correct MM version?
Thanks, and unfortunately not. I reverted back to MM 2.7.6, but the error.log still says that mono.dll caused an Access Violation. I'll delete the SimpleBoiloff.dll and try again. Or should I delete the whole CryoTanks mod? Thanks
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22 hours ago, Phineas Freak said:
You have a ton of mods so everything could go wrong. But for now:
- Module Manager v2.8 is KSP 1.3 only
- SimpleBoiloff is incompatible with RF
Check these two out and report back. If it still crashes then do a binary check to find out the offending mod.
I can't find a SimpleBoiloff mod folder anywhere? Or a SimpleBoiloff mod in general. Am I missing something?
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First of all (not trying to be rude) [snip]
Sorry, I had to.
Second of all, I think that VR is only good for IVA. It would be better to make VR just for that, since it would be quicker and easier than making KSP entirely VR compatible. I also remember that a long time ago, a youtuber (HOCgaming I think) did a KSP VR video with an Oculus Rift, so it's not impossible.
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2 minutes ago, ProtoJeb21 said:
I can name a bunch of films that either have a protagonist from a not-America country, or where Russia is not the antagonist, or both.
*cough* Star Wars *cough*
Okay, that was an obvious one, but name any Marvel/DC films where Russia had any importance?
Fair point, but I wouldn't know about any Marvel/DC movie things since I don't watch them. I'm about ge only person I know who isn't interested in the superhero thing
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3 minutes ago, cratercracker said:
I hate that every film is about America, or about "ze ruzia is or enemi"
I am sick of this.
Like literally, are you still living in the Cold War or something?
Same. I've only seen one movie where the Russians are the good guys, Enemy at the Gates or something like that.
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11 minutes ago, Phineas Freak said:
You have a ton of mods so everything could go wrong. But for now:
- Module Manager v2.8 is KSP 1.3 only
- SimpleBoiloff is incompatible with RF
Check these two out and report back. If it still crashes then do a binary check to find out the offending mod.
Thanks, I'll try that and report back.
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Hi, not sure if I'm posting this on the correct thread, so sorry if I'm not.
So I downloaded the RO/RSS mods, along with some others, but now KSP crashes on loading. The error.log says that mono.dll caused an Access Violation. Can anyone help?
I'm using the latest version I can find of the mods I'm using.
Picture of my GameData folder (sorry for low-quality picture, screenshots aren't working on my computer for some reason):
Here's a dropbox link to the entire crash folder: https://www.dropbox.com/sh/ikfzqfz7bujcv7n/AAAnuooIGr2HXez-3ArCoiw5a?dl=0
Thanks in advance, and if more info is needed, I'll be happy to provide it.
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3 minutes ago, CatastrophicFailure said:
"Hi, Intelsat? This is Elon. I'm not sure how to tell you this, it seems our second stage was a bit peppier than we thought and we just sent your satellite to the Moon. But if you give Jeff Bezos a call he might want to buy it at a fair price."
Speaking of which, are there public figures on how much F9 can take to TLI?
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What are you up to?
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@sevenperforce Makes sense, but I'm assuming it would be extremely difficult to get napalm, especially if the rocket is made just by "some guy" and his team.
On another note, how exactly does one go about programming a rocket? I guess it depends on the guidance computer used.
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4 minutes ago, NISSKEPCSIM said:
Just on quick question: If I were to become a Launch Provider, and I made a fo ket ghat was specifically tailored to be launched using a KOS code, could you launch it with kOS, or does it have to be Mechjeb?
kOS. You'd have to provide the code and everything though, since I know nothing about the mod.
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Looking forward to the rocket stuff
"Hey, look - our stuff can recover even from such seemingly hopeless situation. Aren't we awesome?" 
Amateur rocket to orbit
in Science & Spaceflight
Posted
@sevenperforce I'm not sure I follow your valve idea. Even if you have 6 or 7 valves one after the other, closing just one would shut off the flow, rendering the other valves redundant.