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About sevenperforce

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  1. Every Launch. Real time.

    I check almost daily...I saw that the Long March launch was delayed past March 12, but I never saw it come back up.
  2. Specific Impulse Help

    Sure thing. Fuel flow should be 5 lbs per second, but yes, then that is correct. Again, this works if your fuel flow is 10 lbs per second. You've gotta keep track of your units. People can report fuel flow in a lot of ways: pounds per second, kilograms per minute, tonnes per hour, gallons per mile, liters per all varies. If your fuel flow is 10 lbs per second and your thrust is 1000 lbs, then yeah, 100 seconds. Now we have no units at all. Here's a good example of where the units are tripping you up. If your fuel flow is 100,000 lbs per second and your thrust is 1000 lbs, then your Isp is actually 0.01 seconds. Oops! Well, if you are using lbs/sec for fuel flow and lbs for thrust, then yes, you get an Isp of 34.9 seconds. This is quite right; if you're dumping more than 50 pounds of fuel every second and getting less than 2,000 pounds of thrust, that's a really poor specific impulse indeed. Your propellant isn't even supersonic. Again, no units here. What am I looking at? You could be reporting fuel flow in mpg and reporting thrust in kN for all I know. Gotta get those units. Suppose you want to know the specific impulse of a Cessna propeller engine during cruise. Chances are that its thrust and fuel flow are not going to be given in pounds and pounds/sec, respectively. Only by using units properly will you be able to solve it. For that matter, most rocket engine thrust is given in kN and most fuel flow is given in kg/sec, so that's a whole separate conversion right there.
  3. Every Launch. Real time.

    Shoot, somehow I missed the Long March launch on the 17th. I may go back and do that one....
  4. Eve and Making History

    I've worked for a while on trying to get a reusable TSTO with ground infrastructure, where your lander flies down and couples with the lower stage and is fueled for liftoff, and the lower stage flies back to the launch site like a Falcon 9.
  5. NASA SLS/Orion/Payloads

    Well, Orion's service module isn't done yet. By the time it is done, we'll be flying Commercial Crew with both Dragon 2 and Starliner. Send Orion to LEO on Falcon Heavy, then send crew to Orion on Starliner via Atlas V, then send a single International Docking Adapter into LEO on Falcon Heavy, and use Falcon Heavy's restart capability to perform an eyeballs-out TLI burn. You could also do it all with SpaceX, but that seems unfair and would run into cadence problems since SpaceX only has one pad for FH and it's the same pad for CC. You could send Orion to LEO on Delta IV Heavy, but that seems unnecessarily expensive.
  6. So teach me how to calculate Delta-V in KSP

    Isp is how long the engine could fire if the weight of its propellant was equal to its thrust. It is also the average speed of the molecules coming out of an engine, divided by the gravity of Earth.
  7. NASA SLS/Orion/Payloads

    They can send Orion to the LOP-G without an SLS. Other than pure politics, I don't understand why they wouldn't.
  8. Eve and Making History

    With the new structural shells, I wonder if the reusable TSTO approach might work, using 5-meter parts, Wolfhounds up top, and a ton of Vectors beneath.
  9. Russian Launch and Mission Thread

    On a less political topic, Expedition 56 Soyuz docks with the ISS in about an hour, so here's that mission:
  10. Every Launch. Real time.

    ISS Expedition 56 Docking This is a short one! That's all, folks!
  11. What about: Spacecraft (a reusable manned vehicle which depends on an expendable/separate module for its propulsion) Spacetug (a reusable propulsion module for moving spacecraft around) Spaceship (a reusable manned vehicle with its own reusable onboard propulsion module) That's simple, right? So we've been in the age of spacecraft so far, and we are closing in on the age of spaceships.
  12. If I had my druthers, I'd say to make high-Isp LFO engines run on an alternate fuel mixture. All engines currently run on the exact same mixture of fuel and oxidizer, but high-Isp engines like the RL-10 or J-2 use hydrogen, which is a richer fuel-oxidizer mixture. So the Wolfhound (well, really the Skiff) should do the same. It wouldn't make it impossible for newbies to use these engines, but they'd end up with leftover oxidizer if they weren't careful. It would give another way to use wing tanks in space without throwing an LV-N on. Doubt they'd ever do this, of course, but it would get at the complexities of hydrogen storage and excessive dry mass without having to add a whole new fuel type. I'd also love to see tripropellant engines that can burn LFO+monoprop at high thrust, lower Isp or switch to LFO only for lower thrust, higher Isp. On the subject of fuel and other consumable management, I would REALLY like to see a way to dump fuel. The best way I can think of to do this would be to add an "active cooling" part, which would consume a small amount of propellant (selectable in much the same way as you can select LF, LO, or mono on the convert-o-trons) in exchange for cooling. It could be set to simply dump propellant outright or to dump it in proportion to heat exposure. Same shape as some of the new MH structural pieces; layer them on the surface of your ship and you can use your whole ship as a heat shield.
  13. Something that implies the notion of integrating an upper stage and a spaceship.
  14. Rapiers are good enough on their own if you are only going to LKO. If you are going very, very far with few or no refueling stops, pick a nuke. The middle ground where a Wolfhound might be good is an SSTO with ISRU capability. That high Isp will get you out to Minmus to refuel but you still have better takeoff thrust on places like Duna and Tylo than you'd get with a nuke. The SPS was a biprop hypergolic, not a monoprop. Incidentally, the Puff was the highest-TWR vacuum engine smaller than the Rhino, until the Skiff came along. The J-2 was a gas-generator-cycle hydrolox engine, so it had a median isp of 421s, which is quite close to the 412s which I insist should have been on the Skiff rather than the Wolfhound. That should be the case for every engine. Well, heavy, low TWR, and good Isp as far as bipropellant engines go. Squad hasn't confirmed it, but there are code fragments which suggest a mistake and prerelease descriptions of the Wolfhound talk about its high TWR, I believe. The Apollo CSM SPS was originally intended to be used as the LM ascent engine, so its vacuum TWR needed to be high. I can think of plenty of situations where I needed high vacuum thrust and didn't care as much about ISP. The J-2 was used as a second and third stage in Apollo. Stage 3 of the Saturn V, powered by the J-2, provided the TLI burn; those BLEO burns are where you really want the highest isp. If you're actually going to go somewhere and use an engine to stop, high TWR and low dry mass is the way to go.
  15. Eve and Making History

    Anyone have any ideas on what might be achievable with new stock parts as far as Eve ascent vehicles are concerned? Any chance at a workable Eve SSTO?