Why are multiple engines different?

cjcampbell writes:

The reason we use jet engines is that they are inherently more powerful
and they can operate at high altitudes where the efficiency penalty
compared to piston engines is less. At high speeds, drag is a more
important factor in fuel economy than engine efficiency, so jet
airliners get their best fuel economy at high altitude. But for short
hauls where it would just be a waste of fuel to climb to high altitude
and descend again, a turboprop will deliver more power than a piston
engine with greater fuel economy than a jet.

There are still the questions of simplicity and reliability, which I
thought were both higher for gas turbines. They are certainly more
reliable; and I should think they'd be simpler, too.

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cjcampbell writes:

A lot of the time it just gets down to people having more money than
sense.

There wouldn't be any trace of sour grapes in this, would there?

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Follow on...
http://aeroweb.brooklyn.cuny.edu/spe...ocomm/u-4b.htm
"Gentlemen:

Regarding the U4-B neither the Air Force or any military
branch utilized the Shrike. The U4-B was a 560-A model
Commander by the time it was picked up by the military.
These particular "commanders" utilized the Lycoming GO-480
engines of (275h.p.) later models had 295h.p. The Aero
Commander 680E was the last of the "bath-tub" nacelle
versions used by them.. By 1959 Aero Design of Bethany,
Oklahoma had cleaned up the airframe to include the new
"speed-nacelles" found in all current "Shrikes".. President
Dwight D. Eisenhower flew in one because he was so impressed
with it's safety record, in particular, it's single-engine
safety margins. The prototype flew from Bethany,OK to
Washington D.C. with the left propeller removed and stored
in the baggage compartment. Ted Smith and Gordon Israel had
fabricated one of the nicest Business Twins of the period.
All Commanders exhibit fantastic flying qualities,
rock-solid and stable ideal for IFR operations.
Blue Skies,
International Helio Assoc.
06/30/2005 @ 15:06"

"Jim Macklin" wrote
in message news:BVYWg.2133$XX2.1727@dukeread04...
| Back in the early 1950s, AeroCommander flew a 500, piston
| powered light twin from OKC to Washington, DC with the
right
| prop in the baggage area. Ike had one on the list of
| approved executive travel planes. Ike was a pilot.
|
|
|
| "cjcampbell" wrote in
| message
|
ups.com...
||
|| karl gruber wrote:
|| Some can, easily.
||
|| Karl
||
||
|| Hasn't Bob Hooover demonstrated that in the Shrike?
||
|| "Sylvain" wrote in message
|| t...
|| by the way, that's one of the things that MS FS gets
|| wrong with the light twins: with a long enough
runway
| you
|| can takeoff with only one engine...
||
|| --Sylvain
||
|
|

Mxsmanic wrote:

by the way, that's one of the things that MS FS gets
wrong with the light twins: with a long enough runway you
can takeoff with only one engine...

Why can't you do this in real life?

for one thing you won't be able to taxi, except in
circles; then even if you could line up with the
runway, you won't be able to keep the thing straight,
because the wheels will be able to counteract
the aymetry, and the control surfaces won't be
producing enough aerodynamic force to keep the
thing straight; even if you do loose the engine
once already going, you won't be able to control
the aircraft if you are below Vmc; and even if you
go that fast, you will be unlikely to be able to
climb (which helps when the intent is to get
airborne); the Baron in MS FS has none of these
problems, and is thus not very realistic...

--Sylvain

Mxsmanic wrote:


Nobody can do things that are physically impossible.


except Bob Hoover

--Sylvain

do you know the meaning of the expression 'tongue in cheek'?

I hastily wrote:

because the wheels will be able to counteract

I meant to write: will NOT be able to counteract

--Sylvain

Jim Macklin wrote:
All internal combustion engines work the same. A turbine
just does it as a series of continuous events in different
sections of the engine and a piston engine does one at a
time so power is produced only 1/4 of the time in a 4 cycle
and 1/2 the time in a two cycle.
I'm going to print some T-shirts...

"SUCK
SQUEEZE
BANK and
BLOW

Is there a reason you continually post information that I already know
in my direction?

Jim Macklin wrote:
E90 King Air, F90 King Air 200 King Air. The 300/350 is a
transport over 12,500 pounds and has to do it.

King Air's are not light twins.

Sylvain writes:

except Bob Hoover

Even he would deny that. And he points out that pilots who attempt
the impossible end up dead.

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Jim Macklin wrote:
E90 King Air, F90 King Air 200 King Air. The 300/350 is a
transport over 12,500 pounds and has to do it.


You call those light twins? I call them turboprops. To me a light twin is one
where you can't walk down an aisle inside... ie, smaller than cabin class. That
means airplanes such as the Duchess, Seminole, Aztec, Seneca, C-310, etc.

Compared to airliners, sure, I can see where you might consider a King Air a
light twin. But very few of us get to start in one and yet I do have a bit of
twin time, mostly in light twins and maybe a third of it in cabin class. I
doubt any of them could get out of their own way on takeoff with only one fan
turning.



--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com