GoSlash27

Just got home. It weighs 9 tonnes exactly, so TWR would be 1.36. Best, -Slashy To figure out the burn time of a jet, you need to know the sea level Isp and thrust and the mass of fuel you'll be feeding it with. The Isp figure says "if you convert my thrust to mass and feed me that same amount of fuel, I will stay running for exactly this many seconds". The Wheesley's thrust is 120 kN. divide that by 9.81 = 12.23 tonnes. It's Isp is 10, 500 seconds. If you feed it 12.23 tonnes of fuel, it'd run for 10,500 seconds; 858.375 seconds per tonne of fuel. 2 Mk1 fuel tanks hold 4 tonnes of fuel, so 3,433.5 seconds run time. 57' 13.5". HTHs, -Slashy

That's 'cuz I rounded down If you're interested, I can explain how the math works on that. Best, -Slashy

Well, I cruise at full throttle. I'd have to be home to figure out the twr. As for the burntime, I can calculate that. By my math, a Wheesley would go through 4 tonnes of jet fuel in 57 minutes. Best, -Slashy

2 Mk1 tanks and a Science Jr. The engine is a Wheesley fed by 2 XM-G50 radial intakes. The wings are 4 "wing connector B" panels. The ailerons. They are "Elevon 1" control surfaces. I have them set to respond only to roll. My vertical stab and elevators are "tail fin" control surfaces. The elevators respond only to pitch and the vertical tail doesn't respond to anything at all. I've also disabled the reaction wheel in my cockpit. Best, -Slashy

Schmelge, Well, you'll probably be just fine with the fairing for a nose and the inline cockpit. If it were me, I wouldn't bother with the big battery. The plane doesn't really use much electricity and will still fly even with a dead battery. For advice... Don't be afraid to give it wings. You're going to cruise long distance and land in rough terrain and big wings are a good solution for both of those situations. Best, -Slashy

Schmelge, Just the Wheesley and a couple Mk1 tanks. Are you sure you don't have the Mk1 cockpit? You were supposed to unlock that with basic aviation. Best, -Slashy

This is what I'm using in my current caveman career. It can reach anywhere on Kerbin. Best, -Slashy

Putnamo, I would go with this: 2nd stage: 48-7S Spark with an FL-T200 tank. First stage: 4x24-77 Twitch, FL-T100 + FL-T200. Aerodynamics become a pain when dealing with small lifters like this. You will need a fairing for the interstage to keep it clean. An alternative design. Parallel staging. Center core has an adapter to neck the fairing down to .625, 7 Oscar B tanks, and a 48-7S Spark. The 2 side boosters consist of a nose cone, 3 Oscar B tanks, and a 48-7S Spark. Best, -Slashy

I gather at some point you'll have a vessel named the Benedictus? Excellent cavemannery. Darn near $30,000 is a veritable fortune. Best, -Slashy

I just want you to know... We're all counting on you -Slashy

What Steuben said. We need to know the mass of the payload. Best, -Slashy

severedsolo, I have a tutorial floating around explaining the math behind the spreadsheet. https://forum.kerbalspaceprogram.com/index.php?/topic/122722-how-to-mathematically-design-stages/&tab=comments#comment-2221326 All you have to do is run through this process for all engines simultaneously. You would have a global input panel to input the DV, payload, reference body, parent body, and max/ min atmospheric density. You then solve for a single engine type, and copy/paste for other engines. I recommend doing the crunching on another page so as not to clutter the UI. The answers can then be displayed for all engine types on the UI page. Just plug in what you want to do in the yellow boxes, and the results are displayed below. I really prefer to teach others how to do the math instead of putting copies of my spreadsheets out there for a whole laundry list of reasons, but this should help get you started. Best, -Slashy

I missed it by a year, not concerned. I mean, seriously... it's $15. Who can't afford $15?? Best, -Slashy

Qzgy, It can be done in 2850 m/sec. We've had challenges that demonstrate it. The problem is low DV<> light or economical, so they're not representative of a typical lifter. Best, -Slashy

Temeter, My design parameters for a 2.5m upper stage are 1,650 m/sec DV and minimum t/w of 0.7. The Poodle is the lightest and cheapest stage for 14-20t payloads. The Poodle is the cheapest (but not lightest) stage from 7-14t payloads. The Skipper actually makes the cheapest and lightest stage for 21-45t payloads. Both engines are supremely useful as upper stages. Best, -Slashy

My first Mun landing was in the 0.18.3 demo version. I did all the calculations with pen & paper and a slide rule. Believe it or not, RCS quads and monoprop was the best option for a lander in this version. Best, -Slashy

Gargamel, The problem, at least with my pedestrian spreadsheet skills, is that I can only predict results for relatively simple cases. "If I want a single stage with a known payload, a desired DV, under specified conditions, and a desired minimum acceleration, what would it look like if I used this engine?" I can solve that problem with a spreadsheet because there are only 28 engines in the game. I can solve it for all engines simultaneously, then compare and contrast the results for all engines and pick the stage design that best suits my needs. It's a very powerful engineering tool because it's telling me what I should be building instead of merely modeling what I have already built. If I move into more complicated staging arrangements with multiple engines firing simultaneously, the possible combinations become infinite and I am no longer able to predict a single best case. All I can do is model the behavior of a single design, which is what MJ does. In that case, MJ is superior. It can predict how a specific stage will perform based on what I have assembled in the VAB in real time, requiring no inputs from the user other than building the rocket. Sometimes it will get it wrong, but no more wrong than any other method... I can still have spreadsheets that mimic what MJ does, but they are less efficient because I am forced to effectively build the stage twice; once in the VAB and once in the spreadsheet. In the case of your problem, I have to constrain myself to the condition of the pilot not throttling back the LF&O engine until after staging. I "throttle" the SRBs to provide acceleration limits by having them burn out at predetermined times. No spreadsheet (or mod for that matter) can predict how a rocket will behave if the throttle setting is altered after launch. Best, -Slashy

True. They're calculated assuming mean (circular) orbits and round up to the nearest 10 m/ sec. They also assume real world physics instead of patched conics, so the estimates are a little high. Best, -Slashy

wumpus, The math gets a little more complicated, but not terribly so. spreadsheets work for parallel staging schemes just as well as asparagus or series. Best, -Slashy

And the more kerbals you have on your staff (whether from hiring or rescue), the more exponentially expensive it becomes to hire a kerbal. IMO it should never cost more than $10,000 or so to hire a candidate since that's roughly what it costs to rescue one. Best, -Slashy

Stilgar, Yeah, that's also 200. Best, -Slashy

stilgar, Same principle, but different conversion factor. Liquid fuel and oxidizer 200 Monoprop 250 xenon 10000 Solid fuel 133.3 Best, -Slashy

stilgar, You don't have to drain the tanks to calculate that. Just add the units of fuel and oxidizer and divide the sum by 200. This gives propellant mass in tonnes. Subtract this from your ship mass to get dry mass. Best, -Slashy

It's not the least bit cumbersome for me, since I've built a spreadsheet. I just enter what I need my stage to do, and it tells me what I need to build to make it happen. Which engine to use, how many fuel tanks, percentage to fill the last tank, and how much it'll cost. It's actually *less* cumbersome than mucking about in the VAB with MechJeb trying to T&E a working stage with no idea if there's a lighter or cheaper option available. Bonus: I can do stage design and mission planning when I'm not playing KSP and I never have to worry about updates breaking my game. Same deal with my orbital mech and mission planning spreadsheet. It gives a lot more info than the subway map and allows me to plan pretty much any maneuver. Best, -Slashy

Perhaps. I suspect that they followed Plutarch's mantra on this; the mind isn't a vessel to be filled, but a fire to be kindled. The player would eventually grow tired of guessing and failure and go out and seek the proper way to do it. Could be wrong though, -Slashy