Impact of the R4M if it was ready earlier?

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Tom from Cornwall
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Re: Impact of the R4M if it was ready earlier?

Post by Tom from Cornwall » 26 Aug 2021 17:19

glenn239 wrote:
26 Aug 2021 14:54
The Axis History Forum link I posted suggested about 50 kills by R4M,
I think “suggested” is a bit of a stretch! More like plucked out of mid-air! :lol:

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Re: Impact of the R4M if it was ready earlier?

Post by T. A. Gardner » 26 Aug 2021 17:56

glenn239 wrote:
26 Aug 2021 14:50
Sure, but the problem is that even if only 1 in 6 salvos hit, that's still a massive increase in the lethality of the attacking aircraft per sortie. Also, I'm not a pilot or a gunnery expert but I would assume that R4M would probably be best in a diving or climbing attack where the much larger profile (maybe 2,500 square feet?) comes into play.
The problem is from ahead or astern it's more likely to be 1 in 10 than 1 in 6. The link I posted to the "Battle of Palmdale" is a known example of the use of FFAR--very similar to the R4M--where larger salvos were fired at an F6F drone that wasn't maneuvering from closer range and not one rocket hit the target plane.
At 600 meters the rockets will have dropped about 12 meters due to gravity. That means your aim point on a bomber would roughly be the top of the tail of the plane. An inexperienced pilot would likely not aim well enough in early missions to make the single salvo of rockets work, or he'd have to get much closer--and into the defensive fire of the bomber--to make sure to get a hit. This would make the R4M no more effective than the 30mm Mk 108.
As for best approach, it would be a beam high-side pass maneuver

Image

But that requires the pilot to be trained and proficient at deflection shooting or the aircraft is equipped with a fire control computer system like the Hughes E-1 used on the F-94 and F-89 postwar. You need this because you get one salvo with rockets. With guns you can correct your fire and walk it onto the target if your aim is off initially. You can't do that with rockets.

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Re: Impact of the R4M if it was ready earlier?

Post by T. A. Gardner » 26 Aug 2021 20:43

This photo shows an F-89 firing FFAR rockets. Note the dispersion right out of the launchers.

Image

Here's an F-86D firing them:

Image

What you can see is that the rockets don't fly a perfectly straight and level course when fired in large numbers in a very quick, short, salvo. Instead, some wobble, others almost tumble, and dispersion is increased. I would argue that the R4M would suffer the same issues when fired in a single salvo.

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Re: Impact of the R4M if it was ready earlier?

Post by TheMarcksPlan » 26 Aug 2021 21:58

T.A. Gardner wrote:"Battle of Palmdale"
This isn't a good comparison. Shooting down one drone versus saturating a combat box.
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Re: Impact of the R4M if it was ready earlier?

Post by glenn239 » 26 Aug 2021 22:30

T. A. Gardner wrote:
26 Aug 2021 17:56
The problem is from ahead or astern it's more likely to be 1 in 10 than 1 in 6. The link I posted to the "Battle of Palmdale" is a known example of the use of FFAR--very similar to the R4M--where larger salvos were fired at an F6F drone that wasn't maneuvering from closer range and not one rocket hit the target plane.
1 in 10 means a kill rate of 10% per sortie before a '262 has fired one cannon shell. This would result in prohibitive losses over thousands of fighter sorties. The R4M is a "free lunch" on shooting down bombers no matter how you slice it, because once the rockets are fired the 30mm cannon shells are used next.
But that requires the pilot to be trained and proficient at deflection shooting
Plenty of 262 pilots were proficient in deflection shooting, so you have to figure their kill rate would be much better than 1 in 10.

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Re: Impact of the R4M if it was ready earlier?

Post by Sid Guttridge » 26 Aug 2021 22:31

Hi TMP,

As I understand it, the rockets were not fired at the box but at individual aircraft.

The bombers did not fly wingtip to wingtip, so it seems that only the target aircraft was likely to be at real risk.

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Sid

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Re: Impact of the R4M if it was ready earlier?

Post by T. A. Gardner » 26 Aug 2021 22:48

glenn239 wrote:
26 Aug 2021 22:30
1 in 10 means a kill rate of 10% per sortie before a '262 has fired one cannon shell. This would result in prohibitive losses over thousands of fighter sorties. The R4M is a "free lunch" on shooting down bombers no matter how you slice it, because once the rockets are fired the 30mm cannon shells are used next.
It is more likely a single firing pass is managed. If I were the pilot of one, I'd fire the rockets and continue to approach firing the cannon to make sure I got a kill on the firing pass. After that, I'd likely want to get the hell out of Dodge PDQ because of the escorts. The 262 wasn't immune to interception.
Plenty of 262 pilots were proficient in deflection shooting, so you have to figure their kill rate would be much better than 1 in 10.
By 1944 this is clearly not true. Few German pilots of any sort were proficient in deflection shooting. It wasn't practiced in training. In fact, most pilots wouldn't be proficient at most aerial maneuvers beyond the basics given the brevity of flying hours they were being given.

Here's an experiment you can try. Take a 1/72nd scale model of a B-17 and set it 25 feet from you. That's the equivalent to what a pilot would be seeing against the real thing at 600 yards. Now, imagine that model is moving forward 5 feet per second (250 mph). Try hitting that with a pistol or rifle.

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Re: Impact of the R4M if it was ready earlier?

Post by stg 44 » 27 Aug 2021 02:45

T. A. Gardner wrote:
26 Aug 2021 17:56
The problem is from ahead or astern it's more likely to be 1 in 10 than 1 in 6. The link I posted to the "Battle of Palmdale" is a known example of the use of FFAR--very similar to the R4M--where larger salvos were fired at an F6F drone that wasn't maneuvering from closer range and not one rocket hit the target plane.
https://en.wikipedia.org/wiki/Battle_of_Palmdale
The two crews discussed attack options. Their D-model Scorpions were equipped with the new Hughes E-6 fire-control system with AN/APG-40 radar and an attack-plotting computer, which gave them a choice of two attack options to fire the unguided rockets while in automatic mode: from behind in a "tail chase" situation or a firing pass from a 90° "beam" position. Since the drone was almost continuously turning, they chose the second mode of attack.

Suddenly the drone turned back towards Los Angeles. Einstein and Hurliman were forced to switch from the faulty automatic mode to manual fire. The D-model Scorpions had been delivered with gun sights, but when the E-6 fire-control system was later added, the sights were removed. Now, with the radar-guided system inoperative and no gun sight, the attackers were forced to manually aim the unguided rockets.
Not that close of a range against a constantly turning target while not having any gunsights. The radar gunsight failed and the regular ones removed.

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Re: Impact of the R4M if it was ready earlier?

Post by T. A. Gardner » 27 Aug 2021 06:20

stg 44 wrote:
27 Aug 2021 02:45
Not that close of a range against a constantly turning target while not having any gunsights. The radar gunsight failed and the regular ones removed.
Which with the typical Revi gunsight fitted to Luftwaffe aircraft in 1944 their pilots would have been in the same situation. These were simple reflector gunsights and all aiming calculations were done manually.

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Re: Impact of the R4M if it was ready earlier?

Post by glenn239 » 27 Aug 2021 13:57

Tom from Cornwall wrote:
26 Aug 2021 17:08
Hmm, were they smokeless?
Doubt it, but whatever smoke they made would have made might have tailed off within a short distance of the firing aircraft. The crews would be unlikely to see the rockets themselves - they were tiny and moving at over 500 meters per second.

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Re: Impact of the R4M if it was ready earlier?

Post by glenn239 » 27 Aug 2021 14:09

T. A. Gardner wrote:
26 Aug 2021 22:48
It is more likely a single firing pass is managed. If I were the pilot of one, I'd fire the rockets and continue to approach firing the cannon to make sure I got a kill on the firing pass. After that, I'd likely want to get the hell out of Dodge PDQ because of the escorts. The 262 wasn't immune to interception.
R4M is better than cannons for one firing pass because it has a higher PK than the cannons. If making multiple attacks, it's R4M then 30mm. So, either way you look at it, R4M is better than no R4M.
By 1944 this is clearly not true. Few German pilots of any sort were proficient in deflection shooting. It wasn't practiced in training. In fact, most pilots wouldn't be proficient at most aerial maneuvers beyond the basics given the brevity of flying hours they were being given.
An inexperienced pilot would have a better chance with R4M than with cannons. An experienced 262 pilots (which you seem to be suggesting didn't exist?) I could see becoming absolutely deadly with these things because the PK per firing pass for an experienced LW pilot could be as much as 50% or higher.
Here's an experiment you can try. Take a 1/72nd scale model of a B-17 and set it 25 feet from you. That's the equivalent to what a pilot would be seeing against the real thing at 600 yards. Now, imagine that model is moving forward 5 feet per second (250 mph). Try hitting that with a pistol or rifle.
Try hitting a 1/72nd scale model at 25 feet with a shotgun. See how that goes for the 1/72nd scale model.

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Re: Impact of the R4M if it was ready earlier?

Post by glenn239 » 27 Aug 2021 14:13

Sid Guttridge wrote:
26 Aug 2021 22:31
The bombers did not fly wingtip to wingtip, so it seems that only the target aircraft was likely to be at real risk.

Cheers,

Sid
USAAF bombers flew in combat boxes for self-protection against fighter attack,

https://en.wikipedia.org/wiki/Combat_box

and,

https://b17flyingfortress.de/en/details/formationsflug/


It seems quite possible for an attacking aircraft to fire a rocket salvo from a vector in which multiple bombers are in the line of fire.

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Re: Impact of the R4M if it was ready earlier?

Post by TheMarcksPlan » 27 Aug 2021 19:39

glenn239 wrote:
27 Aug 2021 14:13
Sid Guttridge wrote:
26 Aug 2021 22:31
The bombers did not fly wingtip to wingtip, so it seems that only the target aircraft was likely to be at real risk.

Cheers,

Sid
USAAF bombers flew in combat boxes for self-protection against fighter attack,

https://en.wikipedia.org/wiki/Combat_box

and,

https://b17flyingfortress.de/en/details/formationsflug/


It seems quite possible for an attacking aircraft to fire a rocket salvo from a vector in which multiple bombers are in the line of fire.
Take the example from Glenn's second link of bombers separated by 50ft on the X and Z axes (unspecified on Y but for a diving attack Y wouldn't matter much). Total distance wingtip-nose is ~80ft.

An R4M spread aimed from 600m at one bomber from above could hit a neighboring bomber if off by only 2.3 degrees, either due to salvo dispersion or aiming error. [Tan-1 (80 / 2000)]
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Re: Impact of the R4M if it was ready earlier?

Post by Tom from Cornwall » 27 Aug 2021 20:21

glenn239 wrote:
26 Aug 2021 22:30
Plenty of 262 pilots were proficient in deflection shooting, so you have to figure their kill rate would be much better than 1 in 10.
I've had a quick look at the Forsyth book and he mentions other occasions when R4M was used including:

24 Mar 1945 - against 8th Air Force attack on Berlin. 15 Me 262's of 9. and 10./JG7 - "several of them carrying R4M rockets".

31 Mar 45 - against RAF Bomber Command daylight attack on Blohm & Voss yard at Hamburg "in addition to 30 mm cannon shells, repeated salvos of R4M missiles streaked into the British formation" .

4 Apr 45 - claims against B-24 Liberators

7 Apr 45 - claims of 1 x B-17 and 1 x B-24 by R4M armed M2 262 of III./JG7.

It would be interesting to see Allied reports from those days.

Regards

Tom

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Re: Impact of the R4M if it was ready earlier?

Post by Sid Guttridge » 27 Aug 2021 20:58

Hi TMP, and Glenn239

In much the same way a fan of torpedoes fired at one ship in a convoy might miss and hit others. However, this was purely fortuitous.

Bomber boxes could be up to threequarters of a kilometer wide and, unlike merchant ships, on several different levels. Any hit on an aircraft other than the target would also presumably be purely fortuitous.

Cheers,

Sid.

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