You obviously do knot know the two pointers.

The K2 was only allowed to fly without a HDU fitted to Major Servicings and Return and on dispoal in 1993

No I was a K2 man. I had a look around a couple of K1’s they were totally different fish.
Engines, wings, tanks, electrical systems, APU, an awful lot was different.
Remember 512 well though, used to be called 51/2.

IDLE RPM N1 (not N2) can be as low as 35% for a civil turbofan (CFM56). N2 is much higher – as you say – but N2 has only a limited effect on actual thrust, again for civil engines with large bypass ratio.

That might be Schorsch, we are however posting in MMA. Military a/c especially fighters and bomb trucks have somewhat different requirements. Engine rpm is normally related to the hp compressor. I personally haven’t seen a mil cockpit with more than one rpm gauge per engine. If the Tornado had a gauge per spool there would be six in total, abit much to take in at a quick glance.

& @ scorpion82

pfcem is right here. There is the flight mechnaic perspective, where throttle and thrust are linearly connected and 0% (or degrees, or whatever) give no thrust to the aircraft (but still compensate for the engines drag, which is substantial).

Between IDLE N1 and 100% N1, one can roughly say:
N1 ~ THR^2

~ means proportional

Throttle movement and rpm rise (N2 with fan engines) are not linear. Usable rpm begins around 80-85% to max. Therefore the throttle travel needed from idle to that rpm is normally fairly short giving better control in the area you use the most.

40% throttle setting, not power. The question is how the throttle settings are defined in the F-35. Pcfem suggests 0% is idle and 100% max dry. If we assume that idle is 65% (quite common for military turbofans) than 40% throttle setting would equal 79% RPM. I’m not sure whether that is really realistic, my feeling says no, but who knows. A prove for the claim besides pcfem would be nice, but my request remained unanswered.

55-65% rpm is quite common for idle, the Pegasus being a notable exception.
I’ve always seen the power of an a/c engine expressed as % rpm, overal pressure ratio or Px thrust never as a percentage of throttle movement.
Those are the constants, not position of the throttle.

Pugachev performed his cobra maneuvers for airshow crowds close to the ground. If performed at power with distorted airflow into the inlet, the fan stall margin is not good. If one of the engines were to stall, the thrust from the other widely spaced engine would cause severe yaw which would flip the nose right or left with insufficient altitude to recover before impacting the ground. By reducing thrust to idle, you increase the fan stall margin making the possibility of a fan stall very, very remote. This makes the cobra maneuver safe to perform at low altitude to thrill the airshow crowd.

The stable working line of a gas turbine (fan or otherwise) is normally set at cruise rpm. Higher or lower rpm results in the working line moving closer to the stall/surge margin. It is normally at it’s worst around idle speed. Stall reduction devices (VIGV’s, bleed valves etc) are therefore operating at lower rpm and are gradually shut off as it increases.

We are still using the T Bar engine door keys, alas the top access panels are of the standard DZUS type, so its back to the ol hammer and spanner around screwdriver trick along with dosings of penetrating oil!

Square keys we have, and the tank button tool I have heard of, but what on earth are wobblies!!!?

On a smaller note can we not discuss colors on this thread. The poor guys at Bruntingthorpe are getting a right hammering at the moment for all the wrong reasons and it isnt fair on them.

A square drive GS screwdriver and adjustable spanner is about your best bet with the DZUS fasteners.

Wobblies are T bar sockets for the removal of ‘V’ clamps, they were available in 2BA, 11/32, 3/8 and 1/4″.

I agree with that.

In that order

I assume you are using the ‘T’ bar panel driver on the engine doors. Those stress panel fasteners always were a pain. The Squadrons used to use a cut down driver and a HDU winder for more leverage.

Thanks for that, it’s an interesting read.