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[Sean Mirrsen]

Indeed you waste more fuel by using airbreathers for so long than you'd spend running a couple of more powerful engines (or hell, solid fuel boosters) for shorter.

[Girlinhat]

Thing is, I'm not using any real fuel to get up to 15km.  I've got 3 engines, each is JUST fuel, turbojet, and intake.  Comparable in size to SRB, but they consume so little fuel that I could take a 20 minute slow ascent to 15km and still just be running out of fuel.  Really, if you're able to match your weight against these little JATO modules, it's slow but you can effectively launch a ship from 15km.

The problem is the quirks of violent flameout on jets, when they hit ~16km they SUDDENLY shut off and the effect makes the rocket tumble, so you have to be careful and toss them out before then.  Otherwise, it's pretty awesome.  The ship is 67 tons on the pad, and around 17 tons in orbit, the vast bulk of that being fuel in orbit.  With the single nuclear engine, it could make it to the Mun and back maybe 2-3 times, just in case you wanted to run out there a few times.  Not to mention, probably easily make it to another planet if I could find a decent tool for measuring orbital insertions.

[tryrar]

Thing is, I'm not using any real fuel to get up to 15km.  I've got 3 engines, each is JUST fuel, turbojet, and intake.  Comparable in size to SRB, but they consume so little fuel that I could take a 20 minute slow ascent to 15km and still just be running out of fuel.  Really, if you're able to match your weight against these little JATO modules, it's slow but you can effectively launch a ship from 15km.

The problem is the quirks of violent flameout on jets, when they hit ~16km they SUDDENLY shut off and the effect makes the rocket tumble, so you have to be careful and toss them out before then.  Otherwise, it's pretty awesome.  The ship is 67 tons on the pad, and around 17 tons in orbit, the vast bulk of that being fuel in orbit.  With the single nuclear engine, it could make it to the Mun and back maybe 2-3 times, just in case you wanted to run out there a few times.  Not to mention, probably easily make it to another planet if I could find a decent tool for measuring orbital insertions.

I hear protractor is the perfect tool for the job

[jocan2003]

Use mechjeb ascent function with everything deactivate exept auto-stage. And make sure each asparagus section are on their own stage and in order. It will do just that just jet them as soon they are empty, or on a timer depends on the delay you used.

[alexandertnt]

Using jets for a rocket doesnt seem to work too well with super-heavy payloads, since it takes an awful lot of jets to get it off the ground.

It seems easier just to strap more conventional rockets onto your rocket even if it uses more fuel, its not like fuel is at a premium.

[Girlinhat]

http://www.youtube.com/watch?v=HRh6d2zO4mQ
Behold, it works!

Also behold possibly the slowest ascent ever recorded.  So slow that it starts in reverse!

[forsaken1111]

http://www.youtube.com/watch?v=HRh6d2zO4mQ
Behold, it works!

Also behold possibly the slowest ascent ever recorded.  So slow that it starts in reverse!

Excellent!

[Girlinhat]

Updated video just now with captions, it helps to fill the boring time with reading my slander.

[Sirus]

Very nice slideshow, girlinhat

[Nao]

http://www.youtube.com/watch?v=HRh6d2zO4mQ
Behold, it works!

Also behold possibly the slowest ascent ever recorded.  So slow that it starts in reverse!

Congrats!

The fuel problems are caused by the way girders you use with decouplers. Both the decoupler and the girder segment are "fuel crosfeed capable". It generally doesn't change much if both the fuel line and decoupler are connected to the same tank in case of standard only decoupler design. But the girder segment in your craft id acting like another fuel line thus creating a fuel loop and so the fuel to some engines is flowing through all tanks draining the random tank it ends on. If you want to keep this design i think connecting fuel line from tank to girder and then from girder to another tank could solve the problem.

Also the jet engines are overrated, if you ditched the jets and just put Fl-T400 fuel tank on each of the asparagus stage, you would reach orbit with almost the same fuel and less starting mass (and probably less costly in kerbaldollars).

Cheers!

[tryrar]

Girlinhat, if you used bicouplers to double both intakes and engines, I bet you could get a lot better speed out of the JATOs

[Girlinhat]

Girlinhat, if you used bicouplers to double both intakes and engines, I bet you could get a lot better speed out of the JATOs

I had an attempted rocket to use tricouplers, but the weight was too large to deal with.  You could -probably- get away with a single intake and 2 turbojets, though it's likely to flare out closer to 10km instead of 15km.

Hmm...  If I increase airflow, can they sustain higher?  Time to try and slap bicouplers and see if they'll function at 20km.

[tryrar]

Well, 3 JATO Boosters with tricouplers on both intakes and engines on each of my 4 orange side tanks got my 400ton craft to actually hover(finally tipped over due to clipping the launch clamps ), so I was thinking simply adding bicouplers to your craft should get decent performance increases

[Girlinhat]

Actually, I modified it for tri-mounted turbojets and intakes, and it goes pretty fast.  Each engine has about 10 tons of lifting power, and my 75 ton ship with 18 of these, it shoots up pretty nicely, and at ~15km swap to rockets, the added startup speed means they save even more fuel.

When resource management becomes a thing, these tri-mount boosters are going to be incredible.  They may not be as purely powerful as other sources, but they are cheap, small, and provide reliable lift up to 15km.  I imagine a more 'spaceplane' setup could achieve greater speed around 10km cruising altitude, and release a rocket even closer to orbit.  After all, it would effectively have already done the gravity turn.

[tryrar]

Cool, but I now demand a video of this modded version in action