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-   -   Why do turbine engines require a compressor section (https://www.pprune.org/tech-log/468775-why-do-turbine-engines-require-compressor-section.html)

Lyman 28th February 2012 23:31

the rate of any
 
Hmm. Reverse flow (architecture) supercharging packs gobs more fuel and air into its engine.

Those whose purpose it is to go fast aren't always the huggy fluffs who insist on good economy. Increasing the rate of any exothermia produces more excitement, hence adding more oxygen and/or fuel per event. PACK/POP.

Or push/pop. Choose wisely. :ok:

'pull/bang' is for sissies

thermostat. It may be semantic, but your engine will burn more fuel due its increased supply of O2. There will be more power, and more RPM, and more fuel burned. You will have to rate the engine to keep fuel burn equal to pre boost value, No?

barit1 29th February 2012 01:37

thermostat:

Recip or turbine, more air requires more fuel. The exact ratio will vary slightly (but ONLY slightly) as component efficiencies migrate, but if you've found a way to boost airflow without increasing fuel flow, better patent it REAL QUICK 'cuz you'll soon be a billionaire!

thermostat 29th February 2012 15:13

That's darn good advice. Thanks, you're a good man.
My mechanic says yes, it will burn more fuel. However because of the increased power and better performance you may actually get better fuel mileage. It's like the plane in 'C'; clean up flaps (get rid of the drag as you get rid of lift) increase to 250 kias for more ram and climb higher, faster, on less fuel.
Remember that drag increases with the square of lift; increase lift by 3 increases drag by 9. Get rid of the flap drag ASAP etc.
Back in the 70's the fuel prices increased 6 times, so the airlines were forced to find ways to save fuel. That led to: landing with less flap, shutting down an engine after landing, reducing the flap retraction altitude after T.O., cruising at M0.80 instead of M0.082, planning your descent at idle power until the gear was lowered. We even started the last engine 3 mins before take off. Landing flap taken at 1000ft agl instead of at the FAF. These are procedures that most newer pilots know nothing of. Saving fuel just may keep your airline alive.
Happy landings.
T

barit1 3rd March 2012 01:55

Quite OK, thermostat, I've managed to learn a thing or two after 70 years around planes and engines, and if I'm able to pass some of it along, I'm flattered.

But my original point was that when making a 180, speed is not always your friend. It increases the time and distance required to complete the maneuver; the extreme case being an SR-71 requiring three states and 15 minutes to reverse direction at Mach 3. It's Newtonian mechanics, pure and simple.


"You've never been lost until you've been lost at Mach 3." -- Paul Crickmore

rigpiggy 3rd March 2012 16:44

the airlines were forced to find ways to save fuel. That led to: landing with less flap, shutting down an engine after landing, reducing the flap retraction altitude after T.O., cruising at M0.80 instead of M0.082, planning your descent at idle power until the gear was lowered. We even started the last engine 3 mins before take off. Landing flap taken at 1000ft agl instead of at the FAF. These are procedures that most newer pilots know nothing of. Saving fuel just may keep your airline alive.

regrettably the SOP/Training minions have made this harder to do. I have also had things like "you must be at ref, fully configured at the FAF", "climb at V2+10 up to 1500'", "lack of descent/climb planning ie: descending at 1500 regardless of groundspeed, or climbing best rate into a 100kt headwind"

Common Sense, isn't all that Common


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