High speed and LRC

[fratedaweg]

Could someone tell me the definitin of both:

High Speed Cruise-
Long Range Cruise- ????

[Clandestino]

:hmm: And I thought it was self-explanatory...

In less sophisticated type there are performance tables for high speed or long range cruise. Depending on how expensive the fuel is on the given day and how far you need to fly, company determines which table is to be used. One climbs to assigned level, sets the power and expects to see TAS put down in table... if the aeroplane is fairly new and performance department is not prone to exaggerations.

In more sophisticated types, cruise mach/ias is detemined by FMS after inputting the cost index. Higher cost index means higher cruising speed and vv.

Mind you, long range cruise is not maximum range cruise. Usually 1% of maximum possible range is sacrificed to achieve better speed stability and higher cruising speed.

High speed cruise - well on types that can't overspeed in horizontal flight, one sets maximum cruise power and accepts anything that comes out. On more powerful machines, one flies at some smallish margin below Vmo/Mmo (usually it was 5kt or Ma 0.01 for me).

Sorry if it was unhelpful.

[fratedaweg]

Thanks for your post. It helps.

[Old Smokey]

As one major U.S. manufacturer (starting with a B) puts it -

High Speed Cruise is cruise at either the limiting speed for the aircraft (Vmo/Mmo) OR the maximum speed attainable at Maximum Cruise Thrust (MCR) if less than Vmo/Mmo. Performance tables applicable to High Speed Cruise conform to this philosophy.

Long Rance Cruise is as Clandestino described it.

Regards,

Old Smokey

[C-N]

Could someone tell me the definition of both:self explanatory, and are just Cruise Settings,

LRC - also Economy
NC - Normal cruise
MAX -Best Speed

In a Pilatus (PC-12), its
55%, 65% and 75% of cruise setting respectively.

[Denti]

It gets interesting when your airline starts using CI that result in speed below LRC.