• Content count

  • Joined

  • Last visited

Community Reputation

3051 Excellent

About GoSlash27

  • Rank
    Sliderule Jockey
  1. KSP Calculations Spreadsheet [inDev]

    Pretorian, My excel is just good enough to get me killed. Yes, I believe it is possible to do that... but I don't know how. I have an excel reference book at work. I'll see if I can find the answer on Monday. Best, -Slashy
  2. Auto-Extending Nozzle?

    American ICBMs use this design for compact upper stages. I don't think Isp is a major design consideration for it. I imagine the weight and complexity would offset any efficiency improvements. Best, -Slashy
  3. KSP Calculations Spreadsheet [inDev]

    The old way didn't incorporate thrust requirements, and I only passively mentioned this new process. Yes, in the end you can plug in your mission requirements (payload, ⌂V, minimum acceleration, reference body, and atmospheric pressure) and it will spit out a recipe for the stage, stage mass, and (if you want) total cost. If you apply this to all engines simultaneously, it will allow you to compare the results and choose the best option. Best, -Slashy
  4. KSP Calculations Spreadsheet [inDev]

    Pretorian, First, we generate a "model" of our rocket. One in which the payload is determined by the DV and engine characteristics. Using the REq in it's most basic form, you can generate a wet-to-dry ratio (Rwd) for any desired ⌂V. Rwd=e(⌂V/9.81Isp) Converting Rwd to fuel fraction (Ff) will yield how much of your total mass needs to be fuel. Ff=Rwd/(Rwd-1) Using your fuel tank's full-to-empty ratio (Rfe) (generally 9), you know how much of your total mass needs to be tanks; your tank fraction (Ft). Ft= Ff/Rfe Now we have to determine how much total mass our model comprises, which is how much mass our engine can accelerate at our desired rate. This is based on our thrust, desired minimum acceleration, and local conditions. For a vacuum engine, it's Mtotal=T/ga where Mtotal is total mass in tonnes, T is thrust in kiloNewtons, g is local surface g in m/sec, and a is minimum acceleration in gees. For an atmospheric engine, thrust needs to be scaled with atmospheric pressure. Since thrust scales linearly with Isp, it's a matter of finding your engine's Isp by pressure, then scaling the thrust. Now to finishing our model. Our fuel and tanks are currently fractions rather than masses, so let's fix that by multiplying them by total mass. Mf=Ff*Mtotal and Mtank=Ft*Mtotal Our model rocket's mass is fuel+tanks+engine+payload, and we wish to find our payload, so Mpyld=Mtotal-Mfuel-Mtanks. This model shows the payload a single engine could move at our desired mission parameters, and is scalable to our desired payload. Doubling the rocket would give us double the payload, and so on. We have gone through all this in order to find out how many engines we need for our stage. Neng=desired payload/model payload. Since there is no such thing as a fractional engine, this needs to round up to the next integer. Now we plug this into the REq from the old thread and proceed as described there. Best, -Slashy
  5. KSP Calculations Spreadsheet [inDev]

    Pretorian, That's a pretty ancient thread now. It was all just the rocket equation and algebra, so no references. Is there something you'd like me to elaborate on or explain in further detail? Best, -Slashy
  6. KSP Calculations Spreadsheet [inDev]

    Pretorian, Don't worry about "stealing" anything you get from me or anyone else. We put these things out there because we *want* others to make use of it and expand upon it. As for my further expansions on the reverse rocket equation... I don't know. I'm not playing much KSP these days. If you wish to explore that territory, you have my blessing. Why Lister: I kinda identify with him. I don't take any of this terribly seriously and look vaguely like him. Plus, I'm a Red Dwarf fan. Best, -Slashy
  7. KSP Calculations Spreadsheet [inDev]

    Pretorian, I don't need a copy, but a couple suggestions: You don't need to reverse the rocket equation to find remaining DV. So long as you know the current mass of your ship, the amount of fuel available, and the Isp of your engine, you can calculate that directly. If you carry your "total mass" calculator a little farther, you can get it to design you a stage. Finally, I'd suggest adding a burn time calculator. Best, -Slashy
  8. Spaceplane off EVE!!??

    As the others have said, SSTO spaceplanes do not "reduce the ⌂V required", they actually increase it. The reason they reduce the fuel mass required on Kerbin is the fact that they use air-breathing engines for most of the velocity. An SSTO from Eve is just barely possible if you launch it from a mountaintop, but that's a vertical lifter. A spaceplane to do the same thing is a flat- out impossibility. Best, -Slashy
  9. What are your plans for the solar eclipse?

    Change in plans: Instead of Columbia, MO I will be in DeSoto, MO. There is a tree there that was grown from a seed that orbited the moon on Apollo 14. Best, -Slashy
  10. Caveman heavy lifter challenge

    Gaarst, Amazing! 3.66 tonnes is way beyond what I thought caveman tech could do. Best, -Slashy
  11. Caveman heavy lifter challenge

    Physics Student, Either you misunderstood my intent or I was unclear. I permitted him to adjust fuel in the VAB, not in orbit. When in doubt, simply remember this: the competition is about the lifter, not the payload. You may not utilize the payload to assist you in any way. And before you decide to try it, you may not edit your craft file either. Best, -Slashy
  12. Caveman heavy lifter challenge

    Physics Student, Sorry, you can't transfer your unused fuel into your payload and count it as payload. Your payload must be completely inert; weighs exactly the same in orbit as it did in the hangar. Best, -Slashy
  13. Caveman heavy lifter challenge

    http://s52.photobucket.com/user/GoSlash27/slideshow/KSP/Caveman challenge/130Lifter/GustavIII I've managed to hit 3.2 tonnes with the Gustav III. I'm sure that record won't stand long... Best, -Slashy
  14. What Alshain said. You have unused nodes and parts clipped into non- nodes. This defeats the game's "occlusion", resulting in large flat surfaces exposed to the airflow. Your ship looks clean, but actually has the aerodynamics of a brick wall. That's why you can't get past Mach 1. HTHs, -Slashy
  15. Caveman heavy lifter challenge

    Physics Student, 3.38t is downright impressive! A couple problems: You can't have the shroud attached to the payload. I'll need you to resubmit the entry to correct that. Also, any guidance or electrical storage must be contained in the booster. I'm sure you can still knock it out of the park with a regular nosecone. Containing the guidance in the booster is going to cut down your payload a bit... Best, -Slashy