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Old 04-12-2014, 02:37 PM   #11
Anthony
 
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Default Re: [Spaceships] Winged Spaceships

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There's a formula provided in the designers notes, ISp/3,000 = mps and .05 times thrust-to-weight ratio = thrust for Spaceships, the SSME has values of ISp 452.3 and 65.91, this gives the SSME .1507 then a line of 6's for mps per tank and 3.2955 G for accel.
Spaceships more than makes up for that by ignoring tank mass and atmospheric performance reduction (the SSME has roughly a 20% loss in performance at sea level). In addition, mps should actually be ISp/3,280.
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Old 04-12-2014, 03:00 PM   #12
johndallman
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Default Re: [Spaceships] Winged Spaceships

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TThe Russian's actually got a plane off the ground using them. They did this by removing most if not all shielding from the reactor and using a Direct Air Cycle system, the words environmental disaster spring to mind.
Got a source for that? I like wacky Cold War projects.
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Old 04-12-2014, 03:08 PM   #13
scc
 
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Default Re: [Spaceships] Winged Spaceships

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Got a source for that? I like wacky Cold War projects.
It was a docu I watched years ago, so sorry, no. But you can look up the subject online
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Old 04-12-2014, 03:39 PM   #14
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Default Re: [Spaceships] Winged Spaceships

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It was a docu I watched years ago, so sorry, no. But you can look up the subject online
All I can find is the TU-119, which had some kind of heat-driven turboprops with heat supplied by an onboard reactor, which couldn't have been too critical on weight because several of the test flights were made with the reactor in shutdown.
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Old 04-12-2014, 03:57 PM   #15
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Default Re: [Spaceships] Winged Spaceships

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All I can find is the TU-119, which had some kind of heat-driven turboprops with heat supplied by an onboard reactor, which couldn't have been too critical on weight because several of the test flights were made with the reactor in shutdown.
I know about a test in the USA involving a B-36. The reactor wasn't used to power the aircraft. Just tests to see if a reactor can be carried. The project was canceled due to fears of a crash.
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Old 04-12-2014, 04:10 PM   #16
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Default Re: [Spaceships] Winged Spaceships

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All I can find is the TU-119, which had some kind of heat-driven turboprops with heat supplied by an onboard reactor, which couldn't have been too critical on weight because several of the test flights were made with the reactor in shutdown.
From what I understand the problem comes from trying to use the reactor to power the engines. Basically you can build a plane that has enough lift to carry a reactor, you can't build a reactor that can generate enough power to make the plane fly
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Old 04-12-2014, 04:12 PM   #17
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Default Re: [Spaceships] Winged Spaceships

NASA had a functioning nuclear rocket (not a ram-rocket mind you) in testing for years that had good performance, but required too much maintenance and required too much enriched radioactives to be a serious contender for spaceflight. At the end of the project they pulled the control rods out and caused it to explode, which ****** the Soviets off because of test ban treaties.
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Old 04-12-2014, 05:36 PM   #18
scc
 
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Default Re: [Spaceships] Winged Spaceships

Ok, the reason I asked this question is that I'm working on creating stats for something like the Dassault Aerospace Transporter. For those of you who don't know what that is (Likely most of you) that was something a bit like the Concorde but with both jet and rocket engine, the jet engines would have accelerated it to Mach 2 before the rocket engines took over accelerating it to Mach 4. At that point a separate orbiter, a bit like the Space Shuttle, would separate from it a la the Short-Mayo Composite which then ascends to orbit.

Problems with this is that the booster stage needs to be separately streamlined, and the need for both jet and rocket engines, both of these cut into the fuel percentage, I'm only getting 10 fuel tanks for a measly 2.1 mps out of the tanks using standard values. And it really should have streamlining on the airframe level from Interstellar Wars (Which would help, a single jet engine and fuel tank would provide a staggering 1.32 mps)
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Old 04-12-2014, 06:20 PM   #19
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Default Re: [Spaceships] Winged Spaceships

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Problems with this is that the booster stage needs to be separately streamlined, and the need for both jet and rocket engines, both of these cut into the fuel percentage, I'm only getting 10 fuel tanks for a measly 2.1 mps out of the tanks using standard values.
Well, that's not a problem with the performance rules, it's entirely realistic that you need a fuel fraction of 85-90% to get into orbit. That's a significant factor in why things like the device you're describing have never been built -- they simply can't be built without exotic materials or exotic propellants.
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Old 04-12-2014, 06:41 PM   #20
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Default Re: [Spaceships] Winged Spaceships

From what I understand Jet engines are supposed to help in cases like this, while jet engines weigh more then rocket engines they don't need oxidant. It also avoids the problem poorer performance close to sea levels of rockets, which means you might be able to get away with lower thrust but high ISp designs.

If I switch to a X15-B inspired design things get a little better, but part of my problem is that one of the worlds I'm working with has a higher escape velocity then Earth
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