Air intakes abnormally losing air at low altitudes

[A_name]

I've spent the last few days playing around with SSTO designs and I noticed some strange behavior with the Ram Intakes. The design I was testing used 2 of them (each feeding 1 Turboramjet engine), which yields a total of 2.00 air intake as shown in the resources window.

Under "normal" behavior for this design, the intake air would show as 2.00/2.00 during my initial ascent and would start dropping off above 6 km or so.

However, between test flights I would move around parts and make small adjustments, etc. Sometimes, when launching the plane the intake air resource would immediately drop to 1.90/2.00 or so (these are approximate numbers as I wasn't diligent enough to write them down). During takeoff, not having even left the runway and traveling at 80-100 m/s, the intake air resource would already be down to 1.70/2.00 or so. After taking off, the intake air would continue to drop drastically and by the time I was at around 2kms altitude the Turboramjets would be giving so little thrust that my TWR was below 1.

I was not able to reproduce this behavior reliably but I suspect it might be caused in some way by using the offset tool on the fuel tanks the Ram Intakes were attached to.

Has anyone experienced something similar?

[Murph]

I've not experienced it, that I can think of, but if there's any unnatural clipping or occlusion involved, or completely abnormal part placement, that could easily explain it. With the new aero model, I'd almost be surprised if intake occlusion wasn't included as part of the model, although I don't know if that is or isn't part of the model.

Seems like it shouldn't be too hard for you to test that theory.

N.B. Normally ignore the quantity of IntakeAir, but this sounds like one of the rare situations where that gauge actually told you something useful. Most of the time, that number is about as much use as a chocolate teapot. Assuming that your nose was close enough to prograde, and the intakes were actually pointing into the airflow, then yeah, the thrust dropping off unusually seems wrong.

TWR isn't so important with jets, TWR 1.0 doesn't really matter for them, if anything TWR 1.0 might be overpowered. (Ok, yeah, there is a number, but it's not 1.0, it's much lower, and depends on the overall design, and how well your wings neutralise gravity.) Thrust:drag ratio is the more important thing, i.e. needed thrust scales with drag in normal flight, rather than weight (and drag no longer scales according to weight, under the new aero).

[legoclone09]

Air intake flow is based on speed and position relative to the airflow. You might be not facing prograde, but I have no pictures. Otherwise, I don't know what's wrong but the airspeed may be too low relative to you. But air intakes do drop off rapidly at higher altitudes now, so that may also be the problem.

[A_name]

Thanks for the replies.

To clarify:

-When the problem occurred I was using the same ascent profile as when it didn't occur, so I'd rule out an issue of attitude relative to the airflow, because the same ascent profile worked just fine before. In all cases I was facing prograde or very close to prograde (5 degrees off at the most and only while steering).

-The intakes are not clipped nor are they occluded by any other part, at least not visibly. Maybe the game thinks they are occluded somehow? This would seem consistent with the fact that the problem occurred after adjusting parts with the offset tool.

-I'm running out of air under 5km. Definitely not an issue of being too high.

[MarvinKitFox]

Which mods are you running.

and

Post images of your craft. a *.craft file might be handy too