Kill Ratios

[buffnut453]

Was reading something that referenced a VIII Fighter Command (P-47) study that said the average duration of fire for a successful attack vs. a Ju88 was 15 seconds.

Things that came to mind:

• it's doubtful the Spitfire was ever going to carry 8 x .5in Brownings (probably 4)
• it's doubtful the Spitfire was ever going to carry as much .5-inch ammo in total as the P47 could fire in 15 seconds
• the P-47 is probably a better gun platform than the Spitfire
• while the toughest to actually catch, the Ju88 seems to be the most vulnerable of the three main German types

I think the Hispano was the right call.

Luckily for the P-47, the problems with wing-mounted 50cals were all sorted out before the Jug reached front-line service in a combat zone. Luckily for the RAF, the Spitfire and Hurricane had a viable armament mix that could take down German aircraft in the 2.5 years before the P-47 flew its first combat mission.

Not sure what point you're making relative to kill ratios.

 

[Greyman]

Not sure what point you're making relative to kill ratios.

Less about kill ratios and more tacking into pbehn's post re: .5-inch Browning/20-mm Hispano

Point being - if the P-47 took 15 seconds on average to destroy a Ju 88 with .50s, a .50-armed Spitfire would take even longer, and I think the RAF would find that unacceptable - especially with the 109 escort closing in ...

 

[KiwiBiggles]

Was reading something that referenced a VIII Fighter Command (P-47) study that said the average duration of fire for a successful attack vs. a Ju88 was 15 seconds.

Really? 15 seconds is an awfully long time to be firing. And Fighter Command managed to down Ju 88s in 1940 using only 8 x 0.303. 15 seconds of 0.50 would probably correspond to 60 seconds of 0.303, so something doesn't add up somewhere.

 

[Greyman]

Really? 15 seconds is an awfully long time to be firing. And Fighter Command managed to down Ju 88s in 1940 using only 8 x 0.303. 15 seconds of 0.50 would probably correspond to 60 seconds of 0.303, so something doesn't add up somewhere.

I wouldn't say a .50 strike was six times as effective as a .303 strike - probably closer to two/three times - I'd have to look over some firing trials again.

One thing that's probably different was that many Ju 88 kills in 1940 were against aircraft flying in formation - whereas I'd bet the Ju 88s the P-47s caught were on the run and evading.

Unfortunately I have no other details - just the 15 second figure. Not much to go on.

 

[Shortround6]

You have different criteria or metrics.
Like rounds fired to bring down a aircraft.
or
Number of hits to bring down an aircraft.

Plenty of Spitfires and Hurricanes emptied their guns without a German bomber (or fighter) falling. Poor aim, too far away, whatever.
Average firing time would be in excess of ammo carried.
Germans had the same problem. they figured 15-20 20mm hits were needed to bring down a B-17. They also figured and average pilot only hit with 2% of rounds fired so they needed 750-1000 rounds of 20mm ammo fired to bring down a B-17. Well in excess of what any single engine fighter carried regardless of the number of guns.
The P-47s fall into that pond. 8 guns firing at 13 rounds a second = 104 rounds per second x 15 seconds = 1560 rounds fired X 2% = 31.2 hits needed to bring down a twin engine Ju-88.

Obviously a crap load of variables.
Also averages include the entire spectrum, Pilot A fires fires for 3 seconds (312 rounds fired) to kill his Ju-88 while pilot "B" fires for 27 seconds (2808 rounds , and burns out his barrels) to get his Ju-88. Average is 15 seconds.

While interesting the 15 second number really doesn't tell us much.

 

[pbehn]

One effect of the Spitfire and Hurricanes 8 x 0.303 armament was that although many didn't get destroyed in the air many returned home and were out of service along with many crews.

I think I read elsewhere on this forum that the 0.5 cal guns were in no way reliable in 1936/40 and if you take the Spitfire's 20mm cannon as being three times more destructive than the 0.5 cal then their total armament was about the same.

 

[tomo pauk]

Germans were probably of opinion that there was 5% chance to hit a 4-engined bomber. For what is worth:

One effect of the Spitfire and Hurricanes 8 x 0.303 armament was that although many didn't get destroyed in the air many returned home and were out of service along with many crews.

I think I read elsewhere on this forum that the 0.5 cal guns were in no way reliable in 1936/40 and if you take the Spitfire's 20mm cannon as being three times more destructive than the 0.5 cal then their total armament was about the same.

The Italian 12.7mm Breda-SAFAT was considered reliable much before ww2 started.Ditto for Belgian Browning off-springs.
RAF didn't have to wait for Hispano, Oerlikon was offering several of their models from late 1920s/early 1930s, belt or drum fed, drums being of different sizes (up to 100 rds). Unfortunately, RAF's indecision meant that there was as good as zero of cannon-armed Spitfires and Hurricanes in the BoB.

 

[fastmongrel]

Its been mentioned many times before when comparing the .50 Browning HMG to other weapons. The prewar Browning is not the same as the 1940 onwards Browning. Rate of fire is lower by approx 25%, velocity is lower, terminal energy is lower and Ball rounds with no explosive, incendary and no armour penetrating core were the most common rounds.

A Hurricane or Spit in the BoB with 4x0.50s is not equivalent to a P51B.

 

[buffnut453]

Its been mentioned many times before when comparing the .50 Browning HMG to other weapons. The prewar Browning is not the same as the 1940 onwards Browning. Rate of fire is lower by approx 25%, velocity is lower, terminal energy is lower and Ball rounds with no explosive, incendary and no armour penetrating core were the most common rounds.

A Hurricane or Spit in the BoB with 4x0.50s is not equivalent to a P51B.

Also, wing installation of 50cals continued to have problems until the latter half of 1942 across a range of airframes including the P-51, P-40 and F4F.

 

[tyrodtom]

How many Ju-88s were shot down by P-47s ?

 

[Fighterguy]

Ditto! However there has been at least once incident of an Eagle almost being taken out by an own ship launched AIM-7 from the front weapons station. He recovered. Eagle Standard.

Cheers,
Biff

The early F-15A's experienced engine augmenter (afterburner) malfunctions during station 3 or 7 AIM-7 missile launches. The missile exhaust would enter the engine inlet, starving the engine of air, and causing the malfunction when in full afterburner. This was rectified by the addition of logic within the Engine Electronic Control to signal the Unified Fuel Control to retard to stage one afterburner when a missile was fired (there's five stages of afterburner). This was applicable to the older F100-PW-100 engines.
The one F-15C that was shot by a missile took place during a training exercise out of Elmendorf AFB, Alaska. One aircraft was ferrying a live AIM-9 Sidewinder to the alert station at King Salmon. The other aircraft, the 54th Tactical Fighter Squadron flagship, was leading the element. They proceeded to do some BFM while on the way, and the aircraft carrying the live missile "inadvertently" fired the missile at his lead. The missile blew off the left horizontal stabilator and hydraulic actuator. The aircraft returned to Elmendorf and landed. The pilot stated it flew normal. The mishap caused debate about the effectiveness of the AIM-9 missile, versus the survivability of the F-15. It took about a year to get the damaged fighter back to flying status, and continued for several years until finally relegated to the bone-yard.

 

[DarrenW]

This is an interesting aspect of the cannon vs. machine gun debate :

Vought F4U Corsair - Wikipedia

..... the F4U-1C was similar to the F4U-1D but its six machine guns were replaced by four 20 millimeter (0.79 in) AN/M2 cannons with 231 rounds of ammunition per gun. The F4U-1C was introduced to combat during 1945, most notably in the Okinawa campaign. Aviators preferred the standard armament of six .50 in (12.7 mm) machine guns since they were already more than powerful enough to destroy most Japanese aircraft, and had more ammunition and a higher rate of fire. The weight of the Hispano cannon and their ammunition affected the flight performance, especially its agility, but the aircraft was found to be especially potent in the ground attack role.

Quoted from: Green, William. Famous Fighters of the Second World War. Garden City, New York: Doubleday & Company, 1975 (page 144).

 

[Shortround6]

According the Navy airplane characteristics sheets the 20mm armed Corsair was roughly 300lbs heavier, 12,470lbs vs 12,175lbs.
It was 1 mph slower at 19,900ft, took 12 seconds longer (?) to reach 20,000ft and had a service ceiling 600ft lower, 39,400ft vs 40k.

Firing time should have been about 23 seconds for the 20mm cannon and 30-31 seconds for the .50 cal guns.
http://www.wwiiaircraftperformance.org/f4u/f4u-1d-acp.pdf

 

[pbehn]

According the Navy airplane characteristics sheets the 20mm armed Corsair was roughly 300lbs heavier, 12,470lbs vs 12,175lbs.
It was 1 mph slower at 19,900ft, took 12 seconds longer (?) to reach 20,000ft and had a service ceiling 600ft lower, 39,400ft vs 40k.

Firing time should have been about 23 seconds for the 20mm cannon and 30-31 seconds for the .50 cal guns.
http://www.wwiiaircraftperformance.org/f4u/f4u-1d-acp.pdf

Great post S/R

I think as things progressed from 1939 onwards weight became less of a factor. The Spitfire spanned the whole period but at the end had a 2000HP engine with a constant speed prop. In 1939 many Hurricanes still had twin blade wooden props, there weren't may Spitfires at all. I don't think anyone was jumping at the idea of fitting cannon at that time. If you take the 12 seconds to 20,000 ft to one minute on a 1940 Spitfire it becomes an issue in the BoB. I have read about the travails of Spitfires fitted with the drum type cannon, I havnt read how they did as far as take off and climb performance.

 

[tomo pauk]

Great post S/R

I think as things progressed from 1939 onwards weight became less of a factor. The Spitfire spanned the whole period but at the end had a 2000HP engine with a constant speed prop. In 1939 many Hurricanes still had twin blade wooden props, there weren't may Spitfires at all. I don't think anyone was jumping at the idea of fitting cannon at that time. If you take the 12 seconds to 20,000 ft to one minute on a 1940 Spitfire it becomes an issue in the BoB. I have read about the travails of Spitfires fitted with the drum type cannon, I havnt read how they did as far as take off and climb performance.

In 1936-40 period, French, Germans, Polish and Yugoslavs were normally producing 1-engined fighters armed with one or two cannons. British, Japanese, Czech and Americans were test-flying A/C with cannons for test purposes in that time. Soviets produced small series of I-16 with two cannons in 1938-39.
Both US and UK wasted the opportunity of buying at Oerlikon in mid-1930s, opting to wait for Hispano instead, that went too late to matter for the BoB.

 

[pbehn]

In 1936-40 period, French, Germans, Polish and Yugoslavs were normally producing 1-engined fighters armed with one or two cannons. British, Japanese, Czech and Americans were test-flying A/C with cannons for test purposes in that time. Soviets produced small series of I-16 with two cannons in 1938-39.
Both US and UK wasted the opportunity of buying at Oerlikon in mid-1930s, opting to wait for Hispano instead, that went too late to matter for the BoB.

I think you missed the spirit of my post, the biggest effect of C/S props is in take off and climb. Whatever anyone was researching in the 1930s they needed much more than 1000BHP and C/S props to make them viable.

 

[Shortround6]

Both US and UK wasted the opportunity of buying at Oerlikon in mid-1930s, opting to wait for Hispano instead, that went too late to matter for the BoB.

The trouble was that the Oerlikon came in 3 flavors and wasn't exactly trouble free either.

You had the short case guns 72-80mm case length the FF series, the FFL series with 100mm long cases and the FFS with the 110mm case (this became the famous AA gun) Weights went around 24-26kg then 30 kg and then 39--48kg for the big Oerlikon.

Some of the Oerlikons required greased ammunition to function and that was NOT looked on with favor at high altitudes with freezing temperatures.
Turns out the the Hispano also needed greased ammunition but when initially offered it didn't. Some of the cycle rates quoted for the mid 30s Oerlikons were a little on the optimistic side. But then some of the initial figures for Hispano were on the high side. At least one bbok claims the Hispano 404 was offered at 700 rpm vs the Oerlikons 520 -500-470 depending on model. French service HS 7 & 9s (licensed Oerlikons) were rated at 360-420 rpm.

If you want the velocity and hitting power of the Hispano then you need the Hispano. With similar weight shells the Hispano had a MV of 850-880 m/s the aircraft Oerlikon FFS had a MV 830m/s, the FFL series was 675-750 m/s and the FF was 600m/s.

British and Americans might have bought a shell firing gun sooner than the Hispano but it would have been a lower muzzle velocity, slower firing gun.
better in 1940-41 maybe but not as good in 1943-44-45 let alone post war.

 

[Greyman]

Some of the Oerlikons required greased ammunition to function and that was NOT looked on with favor at high altitudes with freezing temperatures.
Turns out the the Hispano also needed greased ammunition but when initially offered it didn't. Some of the cycle rates quoted for the mid 30s Oerlikons were a little on the optimistic side. But then some of the initial figures for Hispano were on the high side. At least one bbok claims the Hispano 404 was offered at 700 rpm vs the Oerlikons 520 -500-470 depending on model.

I think the lubrication of Hispano ammunition was just for the use in US manufactured guns. It was used as a stopgap solution of sorts for the larger chamber size of the US gun - the heavy lubricant forming a 'fluid fit'. British Hispano manuals (as late as mid 1943, anyway) specifically state that the ammo is not to be lubricated.

The French Hispano fired at 700 rpm, but it was found that reliability and life of the gun was greatly increased if the rate of fire was lowered to 600 rpm - so when the British manufactured the gun the latter speed was specified.

 

[BiffF15]

The early F-15A's experienced engine augmenter (afterburner) malfunctions during station 3 or 7 AIM-7 missile launches. The missile exhaust would enter the engine inlet, starving the engine of air, and causing the malfunction when in full afterburner. This was rectified by the addition of logic within the Engine Electronic Control to signal the Unified Fuel Control to retard to stage one afterburner when a missile was fired (there's five stages of afterburner). This was applicable to the older F100-PW-100 engines.
The one F-15C that was shot by a missile took place during a training exercise out of Elmendorf AFB, Alaska. One aircraft was ferrying a live AIM-9 Sidewinder to the alert station at King Salmon. The other aircraft, the 54th Tactical Fighter Squadron flagship, was leading the element. They proceeded to do some BFM while on the way, and the aircraft carrying the live missile "inadvertently" fired the missile at his lead. The missile blew off the left horizontal stabilator and hydraulic actuator. The aircraft returned to Elmendorf and landed. The pilot stated it flew normal. The mishap caused debate about the effectiveness of the AIM-9 missile, versus the survivability of the F-15. It took about a year to get the damaged fighter back to flying status, and continued for several years until finally relegated to the bone-yard.
View attachment 483294

Fighterguy,

Good info! I'm very familiar with plume ingestion problems from missiles as well as the AIM-9 incident. I flew in the same wing as THAT guy on active duty after returning to the Eagle. Felt bad for him as that could literally have happened to anyone (jumped to a spare when flying with the commander-as a new guy). I'm pretty sure it wasn't to ferry a missile but was a scheduled BFM sortie.

The incident I referred to was a WSEP AIM-7 shot by a LA Guard guy off the front station. Missile suffered control fin failure (AIM-7 it's the front ones) resulting in a 90 degree up maneuver at pickle and going thru the leading edge of the wing. Lots of lights illuminated on the idiot panel. Can't remover if he FOD'ed out an engine or not.

The majority of my Eagle time (17 years total) is with the -220 variant. Nice improvement to the -100 however would rather have had GE-110s.

Cheers,
Biff

 

[tomo pauk]

The majority of my Eagle time (17 years total) is with the -220 variant. Nice improvement to the -100 however would rather have had GE-110s.

Biff - if it is allowed to answer, why would you rather have had the GE-110s instead of P&Ws?