Bomb Fin Advantages

[wuzak]

The difference between RAF GP & MC type fins and USAAF type fins may also relate to the body of the bomb itself. I believe the tail end of teh bomb body of the RAF bombs was mre tapered, and the fins extended further forward. This may give them similar fin area to the US types, or it may simply be a matter of the bombs centre of pressure being in a mor efavourable position, requiring less stabilisation from fins.

Also, when it was proposed to shorten the fins on 500lb bombs so they could fit 4 into a Mossie, the RAF did some tests and found that the shorter fins did not affect the bomb's accuracy to any significant degree.

The balistics of the Tallboy and Grand Slam were tested with a scale, 4000lb concrete filled (IIRC) bomb, possible dropped from a Wellingon. There is a 4000lb test bomb at the aviation museum at Brooklands.

[KJ_Lesnick]

What was the Vickers Scheme-A/-B?

I remember seeing one design that was similar to the B-29 but had six engines...

[pyro-manic]

A and B conventional, C and D the reversed layout with big foreplanes, and E was almost a flying wing.

In high-altitude level bombing, I don't think the fins would really have much more effect than to stop the bombs from tumbling? As long as they fall evenly, that's about as accurate as you could hope for, which is "not particularly" from 20,000ft.

[KJ_Lesnick]

A and B conventional

So they were basically the same, different scale?

E was almost a flying wing.

Fascinating... you have any piccies?

In high-altitude level bombing, I don't think the fins would really have much more effect than to stop the bombs from tumbling? As long as they fall evenly, that's about as accurate as you could hope for, which is "not particularly" from 20,000ft.

Even our bombsights weren't terribly good at 20,000 feet.

[pyro-manic]

Bombsights aren't the issue. It's the couple of miles of air between the bomber and the ground that are the problem.

No pictures - there are a couple of sketches in BSP '35-'45 as I mentioned, but I can't find any online. Worth finding the book though. The A and B are pretty much the same, but B has pusher-props and a slightly different wing shape as a result. They're much the same as the original Vickers Heavy Bomber proposal. The D is, again, similar to the C but with pushers, and the E can best be visualised as a sort of XB-35 shape (very broad, swept wings) but with a stubby fuselage similar to the other designs (as seen in the previous image) but much shorter. Pretty cool.

[KJ_Lesnick]

Bombsights aren't the issue. It's the couple of miles of air between the bomber and the ground that are the problem.

Well, the bombsights do play some issue, but predominantly I kind of figured that out.

The A and B are pretty much the same, but B has pusher-props and a slightly different wing shape as a result. They're much the same as the original Vickers Heavy Bomber proposal.

Vickers Heavy Bomber?  Is that the V-bomber or something else?

[pyro-manic]

The initial proposal for a Grand Slam-only bomber, that was nixed by the Air Staff as too inflexible. The other designs grew from that.

[KJ_Lesnick]

The initial proposal for a Grand Slam-only bomber

And that was the Vickers Heavy Bomber?

that was nixed by the Air Staff as too inflexible. The other designs grew from that.

Ironically, Wallis would have been better off dealing with the more complex circuitry to lay down multiple types of bombs including the 22,000 pounder, as well as the various high-explosives, and incendiaries in the RAFs inventory even if it was a few months later on. 

Regardless, I'm curious why the design didn't follow along a more tear-drop shape: It would have produced somewhat more streamlining and would have possibly been lighter (geodetic construction and all that) though I suppose that's a whole different topic (I wouldn't mind a PM though)

[jcf]

Perhaps because Wallis and Vickers had tried a more 'organic' shape on the Type 271 to
B.9/32 and it proved less advantageous than first believed? Thus the almost total redesign,
which borrowed the basic design and components of the larger Warwick, that resulted in the
production type Wellington.



BTW the Windsor heavy bomber was not directly related the big super-heavies, it originated
from earlier specifications, starting with B.12/36 which produced the Short Stirling.

[KJ_Lesnick]

joncarrfarrelly

Perhaps because Wallis and Vickers had tried a more 'organic' shape on the Type 271 to B.9/32 and it proved less advantageous than first believed?

If I may ask, why did it not work as well as desired?

the Windsor heavy bomber was not directly related the big super-heavies, it originated from earlier specifications, starting with B.12/36 which produced the Short Stirling.

Understood

[wuzak]

This is the wooden wind-tunnel model of the Victory bomber at the Brooklands museum.


Barnes Wallis' Victory Bomber.1939 by PappaDom, on Flickr

[wuzak]

Bristol 100 Ton Bomber

[KJ_Lesnick]

wuzak

This is the wooden wind-tunnel model of the Victory bomber at the Brooklands museum.

Actually that's the picture I've seen before.  However, from that angle it looks very teardrop and circular in cross section.  From the side though it's shape didn't look this way.

Bristol 100 Ton Bomber

How far was this thing meant to go and what payload was it to carry?

The V-tail's nice...

[KJ_Lesnick]

Old Wombat

Possibly in the belief it provided more stability to the bomb?

Possible...


rickshaw

I've often wondered what sort of experimental work was done on bomb design in WWII, particularly amongst the smaller air forces.

That is a very good point...

obviously the larger the fin, the greater effect it would have on controlling the bomb's path.

And I'm not sure how much testing the USAAC did in testing these things: It's possible they based it around this premise


PR19_Kit

You may have been thinking of the Barnes Wallis designed 'earthquake' bombs that had fins specially aligned so that they spun. The 5 ton 'Tallboys' and 10 ton 'Grand Slams' both dropped at supersonic speeds and spun to ensure their accuracy when used with the SABS bomb sight.

I'm curious about something... I was told that in the US there was difficulty predicting the ballistics used in bombs dropping at supersonic speeds.

Did the RAF have this problem?


zenrat

When doing something like area bombing a city with incendiaries then why bother with fins at all?
You don't really need to be super accurate, just drop your load in the right post code.

The idea was to bust open lots of buildings and set fire to the insides in close proximity so huge areas would go up; the fires would then coalesce into a firestorm that would basically suck people, cars, and pieces of buildings into the fires; deoxygenate the air and produce CO gas that would just drop people left and right, produce intense heat that would set more fires.


wuzak

The difference between RAF GP & MC type fins and USAAF type fins may also relate to the body of the bomb itself.

Makes sense: Any pictures of 250 pound, 500 pound, and 1,000 pound bombs used by the RAF and USAAF?

it may simply be a matter of the bombs centre of pressure being in a mor efavourable position, requiring less stabilisation from fins.

That makes sense, though I'm not sure if it's true...

This is the wooden wind-tunnel model of the Victory bomber at the Brooklands museum.

That was proposed in 1939?


joncarrfarrelly

Perhaps because Wallis and Vickers had tried a more 'organic' shape on the Type 271 to B.9/32 and it proved less advantageous than first believed?

Why?

BTW the Windsor heavy bomber was not directly related the big super-heavies, it originated from earlier specifications, starting with B.12/36 which produced the Short Stirling.

Would it have been feasible to fold the Windsor and Victory Bomber specifications together?

A best of both world's scenario with basically the speed, altitude, and maximum payload of the Victory, combined with the Windsor's versatility (payload types), possibly a top and bottom turret if it's absolutely necessary and/or some speed increase.