Ed Rasimus wrote:

On Sun, 7 Dec 2003 16:56:41 +0000, "Paul J. Adam"
wrote:

In message , ArtKramr
writes
Let's take two planes going on low level support missions. They will have to
fly through heavy ground fire including small arms fire. One plane is equipped
with a radial engine,. let's say an R-2800. The other with a jet engine. Which
plane would have a better chance of survival inder these conditions?. Opinions?

My gut feeling is the jet, if only because it's faster and spends less
time being shot at (and the higher deflection makes it harder to hit).
Also, jet aircraft can be pretty tough; stories around about them
surviving assorted insults (going as far as F-105s flying with destroyed
engines, using the afterburner as a sort-of-ramjet) so the survivability
between a jet and a radial recip isn't as pronounced.

After all, either aircraft is equally at risk from hits to pilot,
control surfaces, fuel tanks et cetera... superior survivability of the
engine is a factor, but not the only one (vice the use of P-51s rather
than P-47s in Korea)

Seems to me that you need to define a lot of additional parameters
before you can reduce the discussion to whether a radial is more
survivable than a jet.

If you say same speed, same profile, same airframe, same tactics, same
thrust(power) to weight, same performance, then I'd go to the radial
engine as being one that sustains a bit more insult. But, we've not
added the factor (significant in my mind) about the volatility of
AvGas over JP-4 (JP-8). Wet wing airplane taking a hit in the fuel
tanks? Not pretty.

Glad someone mentioned the fuel difference. Early on, the USN and RN blended AvGas
with kerosene for jets on their carriers, as they still had a lot of piston a/c on
board. The stowage requirements were very different; Kerosene fuel could go in
unprotected fuel tanks just like ship fuel oil, while AvGas had to be carried in
tanks inside the ship's armored box. The British were even more careful with AvGas
than the US was -- they kept it inside the armored box in cylindrical tanks totally
surrounded by water filled compartments. This restricted their AvGas stowage even
more, which is one reason why the British carriers were unable to operate as many a/c
as US ones did.

It was also found that 62% of the single engined jet losses in Vietnam and the middle
east were due to damage to the fuel system. Given the far greater likelihood that a
hit in a fuel tank or line containing AvGas would cause a fire, it seems reasonably
safe to assume that this was the cause of at least as high a percentage of
piston-engined fighter losses in WW2, although no statistical data seems to have been
gathered prior to Vietnam as to specific causes of loss. FWIE, the remaining causes
of loss were pilot incapacitation, 18%, 10% to control damage, 7% to loss of engine
power, and 3% to structural damage. So engine toughness per se was a relatively
minor part of single-engined jet combat losses, at least in the 1960s.

The use of AvGas made it difficult to radically increase the a/c fuel carried by the
Essex class carriers postwar (to meet the needs of thirstier engines), owing to the
fire danger and stowage requirements. The swirtch to a higher and higher percentage
of jets meant they could carry more fuel just about anywhere, allowing over a 100%
increase in a/c fuel carried, which was very necessary to handle the jets' greater
thirst.

But, if you let your jet go faster, pull more G, maneuver more
aggressively, build a tactics package that suppresses the defenses,
etc. then you come up with the undebatable conclusion that the jet
does better.

Have I ever mentioned that FAST is better?

The early centrifugal jet engines like the Nene and Tay seem to have been quite
damage tolerant (the early axials less so, but design has improved a lot since
then). Hre's Gabby Gabreski on his first MiG kill, firing from dead six on a
non-maneuvering target:

"When the sight was squarely on his mid-section I fired a short burst of
armor-piercing and incendiary from the six fifties. I could see strikes all over the
lower section of the fuselage, I kept firing for a couple of seconds and was now
directly astern, about 600 feet back. I centered the sight on his tailpipe next and
gave him another burst. I saw strikes again, around the engines as well as the
wings. Now he went into a slight dive and smoke began to stream back from the
tailpipe.

"I passed over him and broke off to the right and he started down and I kept him in
view. He was losing altitude but much to my amazement, was still under control. I
decided to make another pass from above right; my three Sabres were now strung out
behind me. There was grey smoke from the MiG; he had decelerated. In a matter of
seconds, I closed for another pass, coming in from astern, I got very close and gave
him a good, long burst. This time pieces of his aircraft began to fly off. They
might have been turbine blades from the engine and they passed me on the right. The
canopy flew off. Then the pilot ejected. His parachute opened. We turned on course
for home.

"I was surprised to see how hard it was to bring down a jet, how much damage he
absorbed before he finally went down. Later, of course, we got the bigger guns [Guy:
4 x 20mm M39] in the Sabres . . . these were fifty calibre shells. It took a lot of
them to bring one down."

[Quoted in "F-86 Sabre," by Maurice Allward]

The six .50 cal. M3s in the Sabre fired about 50% faster than the WW2 era M2s in the
P-47, and unlike the P-47 they were all mounted in the nose rather than the wings, so
when you were on target, you were _really_ on target; no need to worry about
convergence range. Elsewhere in the same book, Col. Eagleston (former 354th 'Pioneer
Mustang' group leading ace, IIRR commanded either the 4th Group or Wing in Korea; I
forget which, but both echelons existed) is mentioned as preparing a report stating
that of every three MiGs hit by his Sabres, two had escaped, and that to destroy a
MiG, an average of 1,024 rounds of .50 caliber had been fired. Russian MiG pilots
had a high opionion of the damage tolerance of their MiG-15 engines (essentially
reverse-engineered R-R Nenes), but had a lower opinion of the toughness of the
Sabre's GE J47 axial engine. To be fair, their guns were a lot more powerful than
the Sabre's .50s, so the comparison isn't exact. How well the MiG-15 would have held
up under the fire of a 37mm and two 23mms is an interesting question.

ISTR seeing navy stats that showed Navy and Marine Panthers suffered a lower loss
rate than Corsairs and maybe ADs on ground attack missions; the Panther also used a
license built Nene (J42), and later the larger but also centrifugal R-R Tay (J48). I
don't know how the Banshee, which used a pair of axial engines IIRR, stacked up, but
its involvement in Korea was limited.

It's impossible to make such a comparison on the Air Force side of Korea, as the only
piston fighter they used for ground attack was the Mustang, and there's absolutely no
doubt that a jet is superior to a water-cooled engine in damage tolerance. I've got
the USAF fighter statistical data for the Korean war, and the Mustang's loss rate is
far higher than either of the two USAF jet fighters that were largely dedicated to
ground attack. Here's the Korean War total combat sorties / losses credited to
ground fire / % loss rate (credited) to ground fire per sortie for the F-51, F-80
(centrifugal) and F-84 (axial). I've left out the losses credited to aircraft and
unknown causes:

F-51: 62,607 / 172 / 0.27%

F-80: 98,515 / 113 / 0.11%

F-84: 86,408 / 122 / 0.14%

The Republic F-84's higher loss rate compared to the F-80 may be due to a higher
vulnerability of its J35 axial engine compared to the F-80's centrifugal J33, but
it's also possible that other factors unrelated to the engine may be the cause.
Early on the F-80 flew a fair number of A/A sorties, and while the F-84s of the 27th
Fighter-Escort Wing also flew some, I suspect that the F-84 flew a higher percentage
of its sorties air to ground. The F-84 also came into the war well after the F-80,
so it may be that it was just facing stronger defenses, especially after the front
line had stagnated. The type of ordnance employed may also have affected the time
spent in threat zones, and thus loss rates -- the F-80 fired almost 4 times (80,935
vs. 22, 154) as many rockets as the F-84, while the latter dropped a considerably
higher tonnage (55,987 vs. 41,593 tons) of bombs. I lack the data to reach any hard
conclusions, but the F-84, being from the Republic 'Foundry, certainly had the
reputation of being able to take more damage than its USAF fighter contemporaries.

All in all, though, I'd say the jets have it hands down over pistons, air-cooled or
otherwise, although control issues (loss of hydraulic fluid) for jets that lack
manual reversion or FBW slightly skew things. Given the choice of doing Art's
mission in a P-47/Corsair/Skyraider, or an A-10, I know which one I'd choose, but
that's talking a 30 year technology difference.

Guy