Free Trader Beowulf

Thanks - I love it when people get it :-)

I had the same problem - it's mentioned earlier in the thread. The solution seems to be to activate the engines via staging before trying to activate the reactors via the right click menu.

I did some more science and it looks like your guess is right. I launched a 3 man pod with two radial parachutes and two girders sticking out on either side. If the parachutes were on the ends of the girders, it fell at the predicted 7.7 m/s. In that position they were clear of each other and only partially overlapped the pod. If they were on the pod terminal velocity was 9 m/s. So the pod is occluding the parachutes, and they might be occluding each other. So my calculation isn't too far wrong - I could even calculate the correct value for a simple pod under a single parachute, maybe, as I know the drag cubes for the pods. But even without doing that, I know that I need to spread parachutes out, try to mount them where they won't be occluded by their payload and my predictions shouldn't be too far off. Nice one, FancyMouse.

The drag cube data is in physics.cfg - they look like this: PART { url = Squad/Parts/Utility/parachuteMk16-XL/parachuteMk16-XL/parachuteLarge DRAG_CUBE { cube = PACKED, 0.6278962,0.6383756,0.7139156, 0.6278962,0.6383814,0.7139156, 1.108058,0.7323978,0.6995487, 1.108058,0.9454046,0.1663975, 0.6278962,0.639505,0.7139157, 0.6278962,0.6373008,0.7139157, 0,0.2645478,0, 1.233453,0.6659461,1.233453 cube = SEMIDEPLOYED, 16.39305,0.5255063,1.822568, 16.39305,0.5255054,1.822568, 9.336478,0.1339835,18.06131, 9.336478,0.1646374,18.50363, 16.39305,0.5256646,1.822569, 16.39305,0.5253168,1.822569, 0,9.230829,-1.072884E-06, 3.459486,18.59851,3.459489 cube = DEPLOYED, 53.47527,18.69657,6.152891, 53.47527,18.69662,6.152891, 114.9405,12.06728,18.4375, 114.9405,11.60791,18.7325, 53.47527,18.71372,6.152892, 53.47527,18.67829,6.152892, 0,9.2347,-9.536743E-07, 12.15423,18.60625,12.15423 } } Buried in all that is the data I quoted. Piecing it together from previous discussions of aerodynamics, it seems the drag cube consists of six sets of three values, plus some other stuff. One set is for each face, with the three values being area, drag coefficient and "depth". I just can't quite close the loop to turn that into an accurate prediction of terminal velocity. It also seems that the drag cubes are generated automatically by KSP. I think the values you've listed are left over from previous versions of KSP, certainly I used to use them and they used to work well, but I don't think they are current anymore.

Hi, So, I'm trying to create a spreadsheet to calculate terminal velocity for pods and stuff coming in to land using just parachutes. My calculations aren't working and I need some help from anyone who knows this stuff. I'm starting with the drag equation: F{D}=0.5 ÃÂ v^2 C A Assuming drag equals the force from gravity and rearranging appropriately, I get: V{term} = sqrt( 2 M g / ÃÂ C A) where V{term} is terminal velocity M is vehicle mass in kg g is local gravity ÃÂ is local air density C is surface area A is drag coefficient The drag of a given craft is potentially quite complex, given tip, surface and tail drag and small motions of the craft changing their relationship. However, I'm only really interested in touchdown speed, with parachutes fully deployed. So I assume the only relevant drag is from the chutes and I further assume that it's all tip drag, in KSP terms. So, to get that I've looked at the drag cubes for the parachutes and taken the fourth triplet, which is the drag data for the Y- axis. My assumptions should mean any errors are in the direction that would make my calculations of terminal velocity too high, as I'm ignoring some sources of drag. But I can live with that, I want to know if a given payload can be safely parachuted to the ground with a given set of parachutes. So, I take a simple case, a Mk 1-2 pod is 4.12 tons, and a mk-16xl parachute is .3 tons. From the drag cube I get a fully deployed area of 114.9 m^2 and a drag coefficient of 11.6. g is 9.81 m/s^2 and air density is 1.22 kg/m^3 I calculate: V{term} = sqrt( 2 * 4.42 * 1000 * 9.81 / 1.22 * 114.9 * 11.6 ) V{term} = sqrt ( 86720.4 / 1626.0648 ) V{term} = sqrt ( 53.331453 ) V{term} = 7.303 m/s to three decimal places However, when I actually launch a capsule like that on an SRB and let it parachute back down to Kerbin, the terminal velocity never drops below 8 m/s. It never stabilises entirely, but it's in the region of 8.5 m/s. It's definitely higher than my prediction. I've tried a couple of different tests and my calculations are never accurate. Oddly the mk1 pod I tested under a small parachute fell more slowly than I predicted, I guess its drag isn't negligible when compared to a small parachute. but the Mk1-2 tests always touch down at a higher velocity than I predict. Not a big deal on Kerbin, where I can test things, but a big problem for my Duna and Laythe missions, potentially. If I get an error of 1 or 2 m/s for Kerbin, I might get a much higher error for descents in Duna's thinner atmosphere. So, er, anyone know what I've missed? Thanks

That's one good looking ship - I'm definitely borrowing those drive pods when I get back to building airbreathers. I don't know if it's modelled in KSP, I guess not, but closed wings like that also eliminate wing tip drag, which is non-trivial.

Thoroughness - I appreciate that.

I finally finished sending probes to orbit every moon and planet and measure everything's gravitational parameters. Only took me 1,988 hours. Right, now to send some landers.

Very nice. I sometimes use 2m Kerbin Departure Stages for 1m probes. To keep things looking good and aerodynamic I have to use radial engines for them, as the Poodle is too heavy and the 1m or 0.5m engines just look stupid. But your 2m lander tank would be ideal for that. Nice one.

Randazzo's heat management mod has a 3.75m mullioned heatsink for four standard LV-Ns too.

Just wanted to say that I too think Kosmos SSPP is a great mod, in fact one of my must haves. It's just full of best in class parts - I'm thinking of obvious things like the RCS propulsion units and tanks and the Balka solar panels, but also easily overlooked gems like the LED lamps, which are perfect. If it's not going forward, that's a real shame - but thank you CBBP for a great mod.

:-) Great work with the nuclear tanks - something like that should have been included in KSP 1.0, I guess. Although I'm not going to give SQUAD too hard a time given all the other cool toys they've sent us. But anyway - I really like the ones you've made, just the job for my surveyor fleet. Thanks!

Well that's fantastic news. Have you considered matching nosecones for the 1.25m ones - something the same shape as the Type B advanced nosecone would look great.

Likewise - I still get 0.24.2 when I redownload the Mac version from Steam

Fantastic - I've been hoping someone would have a go at the Rombus or one of Phil Bono's other SSTO concepts. I'd be happy to help test it or look over your numbers :-)