#11
|
|||
|
|||
poor man's rocket
"Zoltan Szakaly" wrote in message I want to come clear here, the reason I am so interested in this because I have an engine that has a high Isp (over 4,000) and is light weight and cheap so it can achieve a thrust to weight of 100. (I realize that thrust is force and weight is mass, I am using the terms loosely here, I am dividing pounds by pounds) I am working on the development of a flying car but I am hoping to also use the engine as a first stage engine to put payloads into orbit. I think the air breather wins no matter what somebody just needs to have enough balls to build one and fly it. Zoltan I've posted an idea for a peroxide powered turbo-prop vtol spaceplane on the halfbakery website at: http://www.halfbakery.com/idea/prope...rocket_20plane I've included a link to an aerobatic plane that can fly vertically in sustained flight (someone else has included a link to a biplane equivalent), a link to Glen Olson's pogo page and a link to Armadillo Aerospace but i couldn't find a link to a self standing, simple explanation of a 'walter style' peroxide turbine. Does anyone know of a site which I could include a link to? Toby |
#13
|
|||
|
|||
poor man's rocket
Penguinista wrote
Still, a jet powered first stage dropping of ~mach 3 could make sense. There are two categories of things that we want to put into LEO - people and dumb mass (satellites, fuel etc). People must ride on man-rated equipment, but that doesn't matter for dumb mass. Not making that distinction is one of the main problems with the STS design imo. In-space rendezvous and docking are well established. People: Take a shuttle and divide by 3. That's nine tons payload. Use five tons in improving reuseability and safety, and perhaps not discarding an ET (though that could even save payload). Spend two tons of that on the single STS engine. Can you imagine what the Rocketdyne engineers could do for immediate reusability with an extra two tons to play with? Or the Shuttle safety guys, with nine tons to play with? I can hear them drooling from England! That's still four tons payload. 20 people at 200 kg, or ten at 400kg. Plenty of carry-on baggage. Let's look at a typical shuttle flightpath. At SRB seperation the mission is flying at 4,300 ft/s and is 41 miles up. It's used up 2/3 of it's takeoff mass. Our 1/3 model would mass around 150 tons at that point. Could we build a jet to do that? Not yet. 3,400 ft/s and 18 miles up is about the limit (SR-71). But we could build a piloted jet with a kerosene/lox rocket boost that would do it, reusing some civilian airliner parts like landing gear. Around 400 tons mission take-off, about the same as a 747. In-air loxing could more than half that, but landing is harder on gear and runways than take-off, so you wouldn't gain much, and the engines have to be pretty powerful anyway! Dumb mass (cargo): Could we also use the jets for cargo? Yes. We'd get around 15 tons useable payload if we used single stage discardable rockets and only worried about pre-separation safety. That's enough for most comsats and the like, and we could also reassemble stuff in orbit if something larger was needed. Build five jets and thirty orbiters, and you have a cheapish, safe, high-capacity man-rated LEO system, which could be in operation in three to five years. No scramjets. No new technology apart from the immediately-reusable engines etc. No SRB's. No ET's. Just two manned, immediately-reusable after refuelling, craft. Just my 2c, and there are probably better ways. A mach ~3 separation would still help. -- Peter Fairbrother |
#14
|
|||
|
|||
poor man's rocket
Earl Colby Pottinger wrote in message
Really, after 100 seconds if your jet works as claimed if you went straight up you would be at 49 kilometers where no jet engine would work well. But your speed would be only 500 meters per second, you still need those rockets, but now you mass ratio is far worse. ... Earl Colby Pottinger My plan is to start vertically and then pitch over to say 45 degrees and sustain 4G acceleration for about 70 seconds. This gets me near mach 8, or 2,700 m/s speed. Somewhere between mach 6 and 8 I close the air inlets and use oxidizer injection. (Here we are no longer talking about a turbine engine, the vehicle under discussion is my ramjet based SSTO) After mach 8 I clearly use the ramjet in pure rocket mode. The SR71 uses turbines but it switches to ramjet mode at some speed/altitude. My "poor man's rocket" would simply be a suborbital spaceplane that uses turbine jet engines with air first and oxidizer injection later. Zoltan |
#15
|
|||
|
|||
poor man's rocket
Henry Spencer wrote
In article , Peter Fairbrother wrote: There are two categories of things that we want to put into LEO - people and dumb mass (satellites, fuel etc). People must ride on man-rated equipment, but that doesn't matter for dumb mass. Not making that distinction is one of the main problems with the STS design imo... Contrariwise: thinking that there is an important distinction there is a sign of the immaturity of the field. Much of that "dumb" mass is extremely expensive. Nobody would ship a $100M satellite to the Cape on an unmanned cargo aircraft. Just reducing the chances of losing the cargo is reason enough to put a crew aboard; any vehicle that is safe enough to carry such costly cargos is safe enough to carry people. (Moreover, any reusable vehicle that is reliable enough to pay off its purchase price is safe enough to carry people. The hard, cold truth is that the orbiters, not the crews, were the biggest losses on 28 Jan 1986 and 1 Feb 2003.) (That's a political reality now, which you would now do better to consider as becoming outdated) The real question is: why are sats so expensive? It's because the mission cost is lower bounded by the launch cost. I could sell a comsat for $1M that would have a 95+% chance of having the same eventual performance as the $100M sat, and pocket more than 1/2 of that to boot. But if my sat went wrong, they'd have to spend another $gazillion cost and wait on the launch of a replacement. That's what they spend the other $99M for. The "guy who pays"(tm) can spend lunch cost or more again on the sat, without significantly affecting his balance sheet. Yes it's a lot more complex than that, and involves many risk calculations, like the availability of funding etc, but as far as he is concerned (and without him it won't happen at all) he can risk twice or more launch cost on the sat. Suppose it cost $500 to launch a satellite, at a 95% launch success probablility. Would anyone risk of a life on that? Would anyone spend $100M on a sat, if they could get a sat with a few fractions of a percent less reliability for $100,000, and they didn't have to spend a $gazillion to launch a replacement? What stopped the STS launches? The bad publicity. People died. The money equation wasn't affected. A far as that went, they could relaunch today. What it comes down to is, you can launch sats at 98% launch success, but you can't launch people at that probability. No matter the financial costings. I give my respect to all who died. I already had it to give. I apologise if any of them seem to be regarded as other than real, living people in anything I have said here. You aren't. -- Peter Fairbrother |
#16
|
|||
|
|||
poor man's rocket
Zoltan Szakaly wrote:
If you do not use turbine blades for intake air compression you save weight and your engine performance will improve with airspeed (ramjet). In general specific impulse for airbreathers will fall off with increased airspeed. At low speeds Isp might increase because of increased efficiency but eventually the airbreather will come against fundamental thermodynamic limits and Isp will drop as airspeed increases. For example, you mentioned that your engine has an Isp of 5000 seconds. Assuming that your engine is indeed an airbreather and that it is hydrogen powered, the highest airspeed at which it can possibly deliver 5000 s is 2500 m/s where it will be operating at 100% efficiency. At higher speeds Isp must go down. Jim Davis |
#17
|
|||
|
|||
poor man's rocket
|
#18
|
|||
|
|||
poor man's rocket
"Zoltan Szakaly" wrote:
The jet engine Isp falls off with speed because the turbine blades become an impediment and the thrust falls off with altitude because of the lack of air pressure. If you do not use turbine blades for intake air compression you save weight and your engine performance will improve with airspeed (ramjet). Thank you for demonstrating you know absolutely nothing about ramjets. This will help to put your future posts in their proper perspective (e.g one of farcical, fantastical, naive, or extraordinarily ill-informed, though there may be other categories I have not identified yet). |
#19
|
|||
|
|||
poor man's rocket
Peter Fairbrother wrote:
Penguinista wrote Still, a jet powered first stage dropping of ~mach 3 could make sense. There are two categories of things that we want to put into LEO - people and dumb mass (satellites, fuel etc). People must ride on man-rated equipment, but that doesn't matter for dumb mass. Um, not if it's *your* dumb mass. Really. If it's your very expensive satellite, you may well want the chances of successful placement into orbit to be pretty close to that expected of a manned vehicle. As might your insurers, if you can get any. Even if it's *just* fuel or water, presumably it was launched to serve some other piece of expensive hardware that's already up there, or waiting to launch soon after, and there may be stationkeeping, life support, or mission launch window issues involved for whatever needs it. Remember, we make no such distinctions with aeronautical or maritime transportation.... |
#20
|
|||
|
|||
poor man's rocket
Joann Evans wrote:
Peter Fairbrother wrote: Remember, we make no such distinctions with aeronautical or maritime transportation.... We do in postage. I usually do not pay more for invitations, bill payments, etc. because the US postal system is good enough. Once in a while I do pay more to have a lower chance of problems (like when I sent our family's 120-yr old Bible across the county back to my Aunt). I think there would be a market for very high reliability launch and high reliability launch. -paul- -- Paul E. Black ) |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Successful test leads way for safer Shuttle solid rocket motor | Jacques van Oene | Space Shuttle | 0 | June 11th 04 03:50 PM |
Private Rocket SpaceShipOne Makes Third Rocket-Powered Flight | Rusty B | Space Shuttle | 10 | May 16th 04 02:39 AM |
Aldrin says we need a larger rocket | bob haller | Space Shuttle | 15 | March 30th 04 01:54 PM |
Rockets not carrying fuel. | Robert Clark | Technology | 3 | August 7th 03 01:22 PM |
Nuclear rocket engine 11B91-IR-100 from Russia | Dr.Ph. Ponomarenko A.V. | Technology | 0 | July 12th 03 09:45 AM |