Corsair as Dive Bomber?

[tomo pauk]

The early Corsairs have had no racks what so ever. The 1st time the rack was installed, it was under the centreline. Later models got two racks under the inner wing portion, the centreline rack being removed. Post war the centreline rack was installed.
The prototype Corsair have had bomb bays in the wings for small anti-aircraft bombs.

 

[stona]

The 1st time the rack was installed, it was under the centreline.

Was that for a bomb or just a drop tank?
I've seen a picture of a rather crude bodge job of a centreline bomb rack on a USMC aircraft, certainly with no kind of displacement gear, but just wondered if it was ever an official fitting. As I said, US aircraft are not really my thing

Cheers

Steve

 

[tomo pauk]

There was no fancy dispalcement gear installed, and it indeed looked like an improvisation of the bomb rack on the F4U-1A (picture of a model).
The later F4U-1D introduced 2 racks, where the bombs were neatly attached.

 

[Dana Bell]

The early Corsairs have had no racks what so ever. The 1st time the rack was installed, it was under the centreline. Later models got two racks under the inner wing portion, the centreline rack being removed. Post war the centreline rack was installed.
The prototype Corsair have had bomb bays in the wings for small anti-aircraft bombs.

Hi Tomo,

Thanks for the correction, but you are wrong about that. The very first 575 production F4U-1s and the first 1247 FG-1s carried a removable Mark 41-2 bomb rack under each wing, just outboard of the wing guns. The rack was used in testing and training, but I've never heard of its combat use.

Records of the XF4U-1 have been tough to track down, but the few documents I've found in the Archives suggest that the internal bomb racks were also intended for anti-aircraft suppression - against shipboard and ground AA guns - rather than the oft listed plan to attack other aircraft by bombing them in flight. This last point is speculation on my part - while the records suggest this, I've never found a definitive explanation of those internal bomb racks.

You might enjoy my two books on early Corsairs:

Amazon product ASIN 0985714972View: https://www.amazon.com/Aircraft-Pictorial-No-F4U-1-Corsair/dp/0985714972/ref=sr_1_9?s=books&ie=UTF8&qid=1479992344&sr=1-9&keywords=f4u+corsair


and

Amazon product ASIN 0985714999View: https://www.amazon.com/Aircraft-Pictorial-No-F4U-1-Corsair/dp/0985714999/ref=sr_1_11?s=books&ie=UTF8&qid=1479992344&sr=1-11&keywords=f4u+corsair


Cheers,


Dana

 

[tomo pauk]

Thank you for the tips.
Hopefully you could post a picture or two where early Corsairs have outboard wing racks installed, but no inboard rack(s)?

 

[Dana Bell]

Hi Tomo,

Try this one:

f4u corsair bomb rack - Google Search

That's a practice bomblet dispenser mounted on the rack. There are far better images in the books...

Cheers,


Dana

 

[tomo pauk]

Thank you for pointing me on the right direction, Dana. I stand corrected
The F4U-1 detailed specification indeed shows two bombs outboard the undercarriage, listing them as 2 x 100 lbs. link
Data sheet for the F4U-1, payload includes a torpedo(!): link

 

[Timppa]

It was very difficult for the pilots to see the dive angle.

 

[Timppa]

Because they wouldn't hit the propeller. Both the the USAAF and the USN established this independently, the USAAF using 'vertical' dives with a P-47. I'd have to look up which aircraft the USN used, but the results were discussed at the Patuxent River fighter conference and I posted the relevant section in another thread sometime ago.
'Vertical' dives, at least in USAAF parlance, seem to refer to any dive at an angle of 70 degrees or more...not necessarily literally vertical.
Cheers
Steve

The bomb definetely accelerates faster than the aircraft, so the pilot did NOT have much time to pull away, in real 90 degree dive..

 

[stona]

The bomb definetely accelerates faster than the aircraft, .

Only the force of gravity could act to accelerate the bomb. Whether it will accelerate the bomb or whether the bomb will in fact decelerate once released depends on the forces opposing gravity, principally the drag of the bomb.
I have no idea how that works out for different scenarios, but knowing the terminal velocity at typical altitudes for the bomb(s) would be a good starting point. Of course it also depends on what the aircraft is doing, since it is the relative motion between the two which matters.
I know Douglas' concern was for 'flapped', presumably meaning 'braked', aircraft which, being designed as dive bombers, might not be accelerating in the dive at all, but be diving at a constant speed.
The automatic pull out system being discussed would start to move the aircraft away from the course of the bomb immediately after separation.
Cheers
Steve

 

[Timppa]

Only the force of gravity could act to accelerate the bomb. Whether it will accelerate the bomb or whether the bomb will in fact decelerate once released depends on the forces opposing gravity, principally the drag of the bomb.
I have no idea how that works out for different scenarios, but knowing the terminal velocity at typical altitudes for the bomb(s) would be a good starting point.
Steve

OK. True vertical dive bomb scenario:
- Typical terminal velocities of the bombs I have have seen quoted is about 600mph.
- F4U limit speed with its gear extended is 250-260knots, or 300mph.
- Half the speed means quarter of the drag force (ignoring compressibility)
- That means bomb acceleration relative to the aircraft is initially 3/4 of "g" .
- The distance from the propeller to the bomb is about 2 metres.
- Bomb will hit the propeller in less than one second after release.

So, IMO, true vertical dive is not possible.
There was a reason for bomb skip arms of dedicated dive bombers, like SBD or Ju-87.

 

[XBe02Drvr]

OK. True vertical dive bomb scenario:
- Typical terminal velocities of the bombs I have have seen quoted is about 600mph.
- F4U limit speed with its gear extended is 250-260knots, or 300mph.

F4U limit speed with its gear extended IN DIVE BRAKE MODE is 350 knots INDICATED. That's 403 mph INDICATED; probably 430 to 450 mph true, depending on atmospheric conditions and altitude.
Better recalculate.

 

[yosimitesam]

Essentially that the aircraft separates from and accelerates away from the bomb.

pp156/7 of my edition of the 'Report of Joint Fighter Conference'.

Commander Monroe:
"Our fighters are authorized to dive up to 85 degrees. Of course they have no displacing gear. Careful investigation down here shows absolutely no danger of the bomb hitting the propeller. At least the airplane and the bomb keep their relative pressures fore and aft, and the bomb drops away from the airplane, which was a great relief to everybody."

This agrees broadly with what the USAAF had also discovered.

Whether 'our fighters' includes the F4U I can't say for sure. The date of the conference was 16th - 23rd October 1944, so it had been in service for some time.

In the interest of balance, I have read somewhere (can't remember where) that Douglas were developing a bomb displacement system powered by a cartridge, and an automatic pull out system, both designed to throw a bomb clear of an aircraft propeller. I don't know which aircraft were involved, and as far as I know such a system never saw service. I would happily be corrected, US aircraft are not really my forte

Cheers

Steve

The bomb ejector was used on the AD Skyraider according to the Pilot's Handbook for AD-2/AD-3 and AD-4. Section 4-19 of AD-2/AD-3 pilot's handbook states:
4-19 BOMB EJECTOR. The bomb ejector provided with the fuselage bomb rack is designed to displace the bomb away from the airplane sufficiently to clear the propeller in steep dives and operates by means of a bomb ejector cartridge.

 

[XBe02Drvr]

The bomb ejector provided with the fuselage bomb rack is designed to displace the bomb away from the airplane sufficiently to clear the propeller in steep dives and operates by means of a bomb ejector cartridge.

By the time VietNam rolled around, and jets were bombing in the compressibity range, ejectors were required on all bomb racks to assure positive separation. In fact, the original A-5 Vigilante failed as an attack bomber because it couldn't eject its ordnance forcefully enough to reliably escape the slipstream.

 

[stona]

And USN fighters, unspecified, were cleared to dive at 85 degrees, close to a true vertical, with no danger of the bomb hitting the propeller.
Same for the P47.
There are complicated aerodynamic forces at work.

 

[Timppa]

,
Better recalculate.

I did, and still the bomb will meet the propeller in one second.

And USN fighters, unspecified, were cleared to dive at 85 degrees, close to a true vertical, with no danger of the bomb hitting the propeller.

F4U, specified, limited the dive angle to 60 degrees, see post #8.

 

[stona]

F4U, specified, limited the dive angle to 60 degrees, see post #8.

By the British, not the USN. I do not know whether the USN applied the same limits to this type of aircraft when dive bombing or not. It might be worth checking though.
Cheers
Steve

 

[tomo pauk]

And USN fighters, unspecified, were cleared to dive at 85 degrees, close to a true vertical, with no danger of the bomb hitting the propeller.
Same for the P47.
There are complicated aerodynamic forces at work.

The P-47 and P-51 were in better position than F4U or F6F when it is about making a dive bomb attack, since the bombs were attached to the wings. The danger in hitting prop was probably not present there, unlike the with USN heavy fighters.

 

[stona]

I have seen other ordnance in this position too.

I've no idea what the configuration for the tests was, but there was obviously some concern that the propeller might be hit, both from the 8th AF and USN.

Cheers

Steve

 

[GrauGeist]

The P-47 could (and did) carry ordnance on the centerline rack.

While they didn't "dive bomb" in the literal sense, they did deliver bombs onto enemy positions from a shallow dive. To what degree on a dive, I am not sure.