Outsourcing my troubleshooting

[Darth Lazarus]

interplanetary enginering ... AWESOME ^^ keep the good work.

[HoY]

Heads up on the design, as you burn your tanks up you won't be able to keep it flying straight. Having the engines out of line with the center of mass, and a center of mass that moves vertically doesn't end well. Good job adopting the dual ports tho make sure you hyper edit them into orbit and test extensively before you put the effort into a real launch !!

Edit: I would consider reconsidering the shielded ports for the time being. There are a few threads by various people who say sometimes those ports bug and don't let you undock again

Edited May 7, 2013 by HoY

[Assault Bunny]

How does one hyper edit?

[HoY]

Hyperedit (my iPhone keeps adding a space as autocorrect) is a plugin that gives you a new menu. The option in the menu you'll need is edit an orbit

Select orbit to edit

Active vessel

Kerbin

100000

That'll put you at a 100km orbit

[Assault Bunny]

Current version of the Arrow:

http://www./?lbgq1tkt6cwtn3h

Stable flight up till I need to switch to rockets, then starts yawing once I have. Just a matter of fuel distribution at this point I think. Also the center jet seems to run out of fuel faster *shrug*

Anyway, if someone could do some magic with the fuel lines, I think I might be in business here.

[Assault Bunny]

I've fixed the rocket stage stability issues with the addition of two tiny radials just above the CoM at the back of the craft:

http://www./?lbgq1tkt6cwtn3h

I also moved around the wing solar panels for aesthetics. It flies pretty good now, though a bit less stable than I'd like, but at least the ASAS isn't going all foamy like with the Dragunov. Now the only problem is I can't seem to get it to orbit.

Little help?

[HoY]

Haha I'll give it a shot, but its more rewarding to do it yourself I've got at least 8 hours of play time tonight I think I can spare this one a half an hour! Need at least 4 hours to make some tutorial videos before I get too tired to speak lol

The first thing I'm going to do is lose all of those solar panels!! I'm not a fan of panels tbh. I know you have them placed around for the rover wheels, but the part count must be kept in mind. Also their usability. With that many of them I'm just going to throw 3 rtg's on it instead lol. Might need to stick an extra battery in it but it will be more functional in the long run (unless you want to park and time warp in the dark)

No joy on the trip to space like I said in the post yesterday, the engines need to line up or the thrust line will change when you switch engines..

Edited May 9, 2013 by HoY

[Assault Bunny]

That's why I added the radials. I got it up to flameout height for the jets and switched to the rockets with no problems, but either I just suck at piloting or it didn't have enough thrust to get much higher. Should I try slapping on a few more intakes to try and get it higher on jets?

[HoY]

the problem I came across, is that at High altitude most SSTO space planes shut off all but a single jet engine to get the longest life out of it possible. Cant do that with this design, so it will just go up on all 3 until one flames out, or until you choose to switch to rockets only.

I tend to ride the jet engines all the way up until the last center engine only puts out 50kn of thrust. If you were to go that high with dual or tripple engines a flameout would take the plane out in a matter of seconds

[Levelord]

the problem I came across, is that at High altitude most SSTO space planes shut off all but a single jet engine to get the longest life out of it possible. Cant do that with this design, so it will just go up on all 3 until one flames out, or until you choose to switch to rockets only.

I tend to ride the jet engines all the way up until the last center engine only puts out 50kn of thrust. If you were to go that high with dual or tripple engines a flameout would take the plane out in a matter of seconds

I solved the problem by vertically stacking my jet engines, but some people might think it's a bit cheaty because it uses some clipping of octagonal struts.

[Rune]

You guys are running into a T/W issue on rocket power, it seems. On rocket takeover, you just don't have enough thrust to offset the gravity losses. There are a couple of different fixes for that. First, you could airhog to higher speeds, either by adding moar intakes, or by throttling down to keep the jets alive (apparently mechjeb 2.0 does that automatically). You could also add more rocket thrust, of course, either by switching the nukes with another kind of engine, or by adding small radials, but that would mean lower isp significantly.

And last, and this may or may not work, you could just slightly change the flight profile. When you are nearing flameout, but not quite there yet, build up lots of vertical speed. How? Well, light the rockets (without turning off the jets), and throttle down to 2/3rds thrust (so you don't flame out for a while longer). Then pitch up to raise you apoapsis as high as you can, and give you time when the jets flame out completely to build speed to lower the gravity losses.

Rune. Hope it helps!

[HoY]

Rune I was trying to get his plane into orbit while only changing the fuel lines for him I would personally have 60 intakes on it if it were mine hahaha. Right to the edge of space!

the problem isnt TWR its CoT compared to CoM when switching to a single engine for higher altitude flight.

[Assault Bunny]

Well, after adding a few intakes, I managed to get it to space. I ran out of fuel beforehand though, so I wasn't able to get a stable orbit. This might work if I add a few more fuel lines... Of course, this means I'll need the longbow, or some other refuelling device, to get it even as far as the Mun. *sigh*

[HoY]

Lol keep plugging away at it you're learning that it takes, and that's the best part of failing in ksp.

I've built 3 different ssto's in the last week, all vertical launch with various sized payloads (40t, 30t and 5t, the 5 being the easiest one to fly and has the most range even when loaded) and it took me about 10 versions for each of them to get working properly!

[Assault Bunny]

Good news everyone! The Longbow MkII has been successfully launched, and is currently sitting in a stable orbit at ~300km!

http://www./?zfu89wu4hn7vb1z (launcher included)

Was a little hairy getting it there. After breaking atmo I dipped all the way down to 40km on Pe, but thankfully I'd built up enough speed that Ap was still around 280km by the time I hit vacuum again. Still, it's up there now, and with plenty of fuel still, though I might send up a tanker to top it up

Now I just need to get the arrow flying right. Current iteration seems to do alright till it gets near the jet ceiling, then it starts dipping the nose down, even with RCS on. If I could keep it level I might be able to build up enough speed then swing it to almost vertical once I switch to rockets. KSP could possibly use a wind tunnel. Anyway, here's the Arrow if someone feels like tweaking:

http://www./?lbgq1tkt6cwtn3h

[Assault Bunny]

Citizens, rejoice!

That's right, I finally managed to get the Arrow into orbit, and even rendezvous with the Longbow! It could still use a lot of work though. I had to expend almost all the Arrow's fuel to get it there, which to me is a very inefficient design, so I'd very much appreciate it if someone could improve things a little. Current version has replaced the old one, so the previous link still works.

Now to refuel from the Longbow and see if the other aspects of the Arrow actually work, like Mun landing, roving, and taking off again.

[HoY]

I don't want to change it myself because I'd end up changing the design lol. Your fuel flowing the way you like it ? You mentioned nose down, is it draining the front fuel tank first or last?

One more thing about the longbow,, just your placement of mono tanks. When you refill the arrow's tank you will be taking fuel from one side, unbalancing the load slightly. You can move the fuel around by eye again to try to balance it, but what I do for this is have one or two mono tanks right on the center line of the ship, and I refill from those until they are completely empty. Then I take the 100 from each of the larger tanks to fill th two small tanks that are in the center. It keeps your center of mass from shifting. Just remember to always do it in pairs

I know you have the 2 100 tanks on your docking struts, those might be close enough to the center so that if one is empty and the other is full your command pod torque will be able to overcome the imbalance

Edit again. I just noticed that you have Lots of little RCS tanks near the center lol. Same rule applies just drain in pairs top and bottom pairs first as those will effect the com the least.

Edited May 11, 2013 by HoY

[Rune]

Congrats! When you are more proficient with SSTO's, and have seen how other people do what they do, I'm sure you'll be able to tackle the much harder problem of the "SSTMun" mission. I mean, once you can do that, there's little else you can do with SSTO's in terms of performance, since Laythe takes about the same. Duna?

Rune. I really should move the pace of my game along. Too much time designing and not nearly enough on timewarp!

[Assault Bunny]

Well, I've discovered landing correctly is quite difficult. Also that the pilot module by itself can dance HoY, I also have 2 of the large propellant tanks on top of the orange fuel tanks. In terms of how the fuel drains in the Arrow, I'm not entirely sure, but everything feeds from the two long rocket tanks. I'm fairly sure the CoM shifts down during flight, probably forwards too. In any case, feel free to change any of the wings apart from the deltas, and possibly the tails fins on top. I've also had a thought to add a third landing strut along the belly, to help with the hard landings I'm having, though I still haven't tested out the rest of the Arrow's functionality.