Author Topic: F4U-1C Gun troubles  (Read 591 times)

Offline Rino

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F4U-1C Gun troubles
« on: May 14, 2005, 07:36:12 PM »
I was digging through some book shelves the other day and
found my copy of Aces Against Japan by Eric Hammel.  I'd highly
recommend all the Aces series as they are straight from the
horse's mouth as it were.

     On reading Lt Joe Robbins story of flying with VF-85 off the
Shangri-la, I saw something interesting.  Apparently the 20mm
cannon used by VF-85 would freeze above 15,000 feet.  They
had to equip the guns with heaters in theater and hand off the
higher CAP alts to the 50 cal armed Hogs.  It seems the high
alt gun tests back in the US had been cancelled so the problem
was not discovered till combat..yikes!
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PHAN
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Offline Tails

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Re: F4U-1C Gun troubles
« Reply #1 on: May 14, 2005, 07:40:11 PM »
Quote
Originally posted by Rino
I was digging through some book shelves the other day and
found my copy of Aces Against Japan by Eric Hammel.  I'd highly
recommend all the Aces series as they are straight from the
horse's mouth as it were.

     On reading Lt Joe Robbins story of flying with VF-85 off the
Shangri-la, I saw something interesting.  Apparently the 20mm
cannon used by VF-85 would freeze above 15,000 feet.  They
had to equip the guns with heaters in theater and hand off the
higher CAP alts to the 50 cal armed Hogs.  It seems the high
alt gun tests back in the US had been cancelled so the problem
was not discovered till combat..yikes!


What I would like to know is how a gun 'freezes' like that?

Is it condensation icing up in the internals? Or is it dissimilar steel alloys contracting at different rates up there?
BBTT KTLI KDRU HGQK GDKA SODA HMQP ACES KQTP TLZF LKHQ JAWS SMZJ IDDS RLLS CHAV JEUS BDLI WFJH WQZQ FTXM WUTL KH

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Offline Rino

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F4U-1C Gun troubles
« Reply #2 on: May 14, 2005, 07:57:13 PM »
The book never says what caused the freezing, only that the
squadron's pilot performed tests and that the cannon would
cease functioning above 15K.

     My own pure speculation would be that possibly the 20mm
used different or more lubricating oil than the 50 cal.
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PHAN
Proud veteran of the Cola Wars

Offline Bodhi

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F4U-1C Gun troubles
« Reply #3 on: May 14, 2005, 08:24:21 PM »
it is the lubricating oils and greases that cause the guns and cannons to freeze.

The Luftwaffe had problems in Russia with this, and in Hartmann's biography he described how they figured out how to fix it...

a captured Soviet armorer showed them by boiling how water in vats, then soaking the guns and cannons in them to remove and grease and oils then thorughly drying them, then reinstalling and firing them dry.  While not great for longevity, it certainly worked.
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Offline Sikboy

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F4U-1C Gun troubles
« Reply #4 on: May 14, 2005, 08:36:42 PM »
Must be a spring cleaning thing. I'm reading the same damn book after finding it in a box.

-Sik
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Me: Meh, whatever.

Offline Rafe35

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F4U-1C Gun troubles
« Reply #5 on: May 14, 2005, 09:49:05 PM »
Me and Brady discuss about F4U-1C Gun trouble from last year I believe.

F4U-1C Groups will have to stay at 10k level or lower after some testing by US Government.
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Offline Squire

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F4U-1C Gun troubles
« Reply #6 on: May 14, 2005, 10:06:12 PM »
P-38 pilots did the same thing in the ETO, they learned it from the B-17 gunners. Removed the grease, and therefore the freezing problem.
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Offline bunch

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F4U-1C Gun troubles
« Reply #7 on: May 14, 2005, 10:34:01 PM »
Per Supermarine test pilot Jeffrey Quill's book, C wing Spitfires had this trouble with the outboard cannon, but not cannon in the inboard position.  Heating was sufficient for the 0.303s, though, in the outboard position.  If F4U-1c really had this difficulty, it suggests a real lack of communication between the A/C manufacturers, especially since FAA was ordering both the cannon equipt F4Us & Seafires

Offline Tony Williams

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F4U-1C Gun troubles
« Reply #8 on: May 15, 2005, 12:05:48 AM »
The RAF discovered the gun freezing problem in 1940 (as did the Luftwaffe); it wasn't confined to any particular type of gun, although the Hispano was more prone to it than the Browning.

The RAF identified in 1940 two different causes of Browning .303s freezing; first, the congealing of the gun lubricant, and second the formation of ice on the gun mechanism.

The British solution was to change the lubricant for an anti-freeze type, made by mixing anti-freeze oil and paraffin. This worked, but it had poor anti-rust properties which increased the difficulties of maintenance.

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Offline bunch

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« Reply #9 on: May 15, 2005, 12:38:50 AM »
Well, there goes my explanation of there were no 4 cannon C-wing Spitfires.  Thanks for nothing, Tony
J/K

Offline Waffle

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F4U-1C Gun troubles
« Reply #10 on: May 15, 2005, 02:55:33 PM »
odd - p47 as well as others had gun heat controls. It's suprising that since there was a "war" going on - this wasn't common knowledge and it wasn't installed on all planes.

« Last Edit: May 15, 2005, 02:57:43 PM by Waffle »

Offline Tony Williams

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F4U-1C Gun troubles
« Reply #11 on: May 15, 2005, 07:10:16 PM »
Sorry, I should perhaps have made it clear that the British had gun heating also (in fixed gun installations - usually by diverting hot air from the engine cooling system) but it wasn't always adequate. And they were never able to adequately heat bomber defensive guns (the only feasible method was electric, and it would have soaked up too much juice).

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Offline Rafe35

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F4U-1C Gun troubles
« Reply #12 on: May 15, 2005, 07:55:06 PM »
"Following Bunker Hill's retirement, Essex and Benningon's F4Us would only be accompanied by Shangri-La with Air Group 85 aboard. Lt Joe D Robbins (5 kills) was assigned to VBF-85 which flew the F4U-1C. He had previously gained two victories flying the F6F with VF-6 aboard Interpid.

'On 8 April 1945, we departed Ford Island and and on 26 April 1945 we joined the carrier Task Force off Okinawa. We had 16 carriers making up three task groups. One Task Group would replenish each day whilst the other two would be hitting targets in Japan. On 4 May 1945 I was the flight leader for 12 F4U-1Cs flying CAP over a destroyer 12 miles north of Okinawa. The Japs were sending planes from Japan to attack our forces on Okinawa and ships at sea. At times kamikaze planes would be at a low altitude with fighter cover at a higher altitude. Our mission was to intercept and shoot down these aircraft. We launched in the early morning from the Shangri-La and took up our station. As always, we charged and test-fired our guns after take-off. My divison was assigned an altitude of 20,000 ft, whilst the second divison was at 10,000 ft and the third 5,000 ft. We have been on station a short time when at 0830 we received a vector at distance 26 miles to a bogey, and we were told that it was below us. I had fuel in the belly tank and I didn't want to drop it until I saw the bogey.

'These flights were about four hours long so you didn't want to drop the tank until you had to. I had my left hand on the switch in preparation, ready to go to the main gas tank and drop the belly store when I saw the bogey. We were all looking down when all of a sudden about 30 Zekes came from above and attacked us. We didn't see them approach as it was hazy and we had also been told they were below us. I switched tanks and dropped the belly tanks and made a sharp turn all at the same time - I had to. By doing this, however the engine was not getting any fuel, so it stopped. It takes only a few seconde to switch and get suction again, but I didn't have that few seconds. You don't get suction when you are making sharp turns and I was really making them. One plane was in my gun sight coming from the 10 o'clock position. I tired a 30' deflection shot and pulled the trigger; no guns. I was banking right and then left as steep as I could to keep them from shooting at me, still no engine. I kept recharging the guns and still they wouldn't fire. I kept banking one side and then to the other, keeping my nose down and losing altitude. I had at least four of them in my sights, but my guns wouldn't fire!

'These enemy planes were escort cover for some kamikaze planes below. Although I wasn't hit, they shot down my wingman, Frank Siddall, and second section leader, Sonny Chernoff, and then they left. The divison at 5000 ft then intercepted them. I was at about 16,000 ft when I got my engine started, and I followed my wingman down and he made a good landing in the water. I stayed over him until a destroyer picked him up 35 minute later. The destroyer that rescued him, the St. George, was hit by a kamikaze two days later while he was still aboard.

'Out of the four planes in my division, none of the guns would fire. At that time were the only Navy unit that had the 20 mm guns. That afternoon they were tested at high altitude and it was found that they froze and would not fire at about 15,000 ft. We checked with Washington and learned that the flights that were to test them at high altiude had been CANCELLED! From then on were restricted to 12,000 ft until we got gun heaters. We still flew CAPs and target strikes below this altitude. VBF-85 (.50 cals) flew the higher CAPs.

- - The Blue Devils books by Mark Styling & Barrett Tillman"
Rafe35
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Offline bunch

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F4U-1C Gun troubles
« Reply #13 on: May 16, 2005, 02:25:06 AM »
They could have removed the high alt equiptment (O2, cockpit heat, turbosuperchargers, etc) also to increase performance below the new ceiling...anyone know if the cannon armed F6Fs had gun heating?