turbojet enginge working in space

[holmes323]

So I Have just noticed a bit of an anomaly regarding airplanes. I was testing out a airplane it had enough intakes to get to 30Km however once it reached 30km the intake air read 0.00 however the four turbojets never flamed out and continued to produce 6Kn's of thrust apiece even after shutting down the engines and restarting them in space(above 70Km) I was able to get this purely air breathing plane to achieve a 150x150km orbit and was able to deorbit from said orbit and land. has anyone else experienced this bug? I used purely stock parts to build it but have mechjeb, flight engineer and kerbal alarm clock installed none of which should modify the behavior of the stock engines.

[Captain Sierra]

???????? uh WHAT!? THe guys over at the SSTO (single stage to orbit) megathread would love to hear about this!

Now in all seriousness, if you throttle jets down, 1) they have a spooling and 2) they can in fact run at near 0 throttle up to 40+km. That said, unlike the real atmosphere which has an exosphere that *could* account for enough air to barely run the engines, KSP atmospheres don't taper off that much. Kerbin's atmosphere just stops at 69.9km altitude. at 45km, its possible to be getting something like 0.006 intake air, which wouldnt register on the UI but still be there. By game code, above 70km you cannot gain intake air.

There is however a possibility that you brought trace quantities of canned air with you. Intakes store air. Unrealistic as this is, it has to do with the way intakes are coded. What may be happening is you have 0.006 intake air stored in your intakes and your engines are able to consume that. The fuel consumption of a turbojet engine at 6kN is very, very low. You may have unknowingly been storing enough air to do that. There were some people a while back in the SSTO thread who used radial intakes (high air storage) to bring canned air and make all-jet SSTOs that had no rocket fuel and used RCS to de-orbit. Closing the intakes and disabling resource flow let them store it until they needed it in orbit. Thats possibility 2.

Oh and welcome to the forums buddy!

[panzer1b]

If you truly airhog (say 2 or more RAM intakes/ton of craft), you can get a 200km AP with nothing but jets, and you still get some thrust at around 69km (the cutoff altitude).

Realistically flawed, in terms of STOCK aerodynamics (and extremely thick atmo even very high up), the jets are just overpowered as they can both function above a very high speed cutoff (2400m/s for turbojets surface velocity), and can have intakes abused/stacked in such a way as to basically get air at the highest parts of atmo (and even 5 kn thrust at that altitude will add alot to your orbit). Rapiers are imo a LITTLE more balanced (2200 m/s cutoff makes them unable to break atmo and give you a high PE, meaning you either need to use rocket mode, or switch to something like a nuke). Actually, rapier's more plausible preformance (+ looks and thrust vectoring) is the reason almost all my SSTOs use them, the turbojets are just so overpowered in their current form.

ofc, the whole atmosphere being thicker at high alt helps jets way too much, and also harm anything that isnt air-breathing (if you arent using jets within atmo, you are fighting both drag and gravity the whole time until you break the 69km barrier).

[Brainlord Mesomorph]

I had a bug when .25 first came out.

I cut a orbit insertion burn and looked at the map and my orbit was changing!

I checked, all engines were off but I was still getting delta V from something or somewhere. ruined the orbit.

had to quit out and reboot.

never happened again.

[holmes323]

It now appears to be a true bug as after further testing I was able to have a jet plane takeoff with zero intakes the image should be proof enough that there is a bug afoot here.

[numerobis]

Did you turn on infinite fuel in the debug menu?

[mckamx]

Your resource list is not showing IntakeAir at all, indicating that something screwy is happening with your Turbojets.

[GoSlash27]

Yeah, his engines are lit, yet his resource panel shows no draw. I think his infinite fuel is on.

Best,

-Slashy

[Empiro]

I think I've definitely run into a similar bug before. I could get my RAPIER engines to operate in Air Breathing mode well after the intake air had run out at 40+ km. I couldn't reproduce the issue though, and it went away after a reload.