How do air breathing engines work?

[Nich]

It seems to me there thrust is based entirely off there speed and altitude and intake plays no part. I am attempting to make a low tech SSTO spaceplane using wheasles and ram air intakes.

I have tried 5 engines 10 intakes with a total air intake of 8 or 9 (worst results lowest slowest)

5 engines 5 intakes giving 5 total air intake (same)

5 engines 1 intake giving 1 total air intake (best highest fastest)

[LordFjord]

SSTO with wheesleys will be hard. They are simply not meant to fly fast and at high altitudes.

What you probably witnessed is this:

- more intakes generate more drag

- the wheesley engines flame out relatively early, you probably flew with a steep ascent profile so you most likely crossed the boundary of "engine works with very low air" and "engine has no air at all" very fast -> the number of intakes does not play a big role in this case

- due to the previous points, your design with the least intakes was the most successful as it had the least drag

It is surely possible to build a low-tech SSTO based on the Wheesley engine, but its relatively hard.

I would suggest to at least get to Whiplashs before considering an SSTO - or build one that works only on rocket engines.

More info on intakes:

- intake air resource flow - this is old but works still the very same way

- check the link in my sig might help preventing asymmetric flame-outs

Let us know if you need more help, a pic of your design will get you a lot of usually constructive feedback.

Fly safe,

Fjord

Edited June 23, 2015 by LordFjord

[Nich]

Thanks that explains why I was veering during take off.

Although I am still confused in the wheesleys description it says they can use up to 2.25 or something resources of air however even with 5 running off 1 unit of air they still ran at 110 kN (most I have been able to achieve as I have yet to see anywhere close to the 167 listed in the description.

[capi3101]

Wheesley's are designed as low-altitude engines; you won't go much above 15k on them before they flame out and even then you'll be lucky to top Mach 1 (if you do, it'll probably be in a dive). Best to save up the tech and unlock Whiplash engines; those have a shot of getting you high and fast enough.

[pincushionman]

Wheasleys are pretty much for:

1) Flying at Kerbin

2) Learning to build and fly planes before graduating to the "big boy" toys - Whiplashes and RAPIERs. Kinda like how Fleas are the "starter" rocket engine.

[NathanKell]

15km on Kerbin is 18.75km on Earth which is 61,500ft. Pretty high for (non ram-)jets.