Westland Whirlwind revisited

Wild_Bill_Kelso said:

Hold on, something doesn't quite add up there. Going from 4 .30 caliber M1919 machine guns and ammo, to 6 .50 caliber M2s with ammo, I would think that would be more than #100

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That was the change in the structural weight of the wing. If you want to put in six .50s plus ammo and still pull 8 'G's you have to beef up the wing.
Weight of brackets, mounts, cabling, ammo boxes/chutes are in a different catagory.

And at times weights get shifted from one catagory to another. P-40s up until F list the armor and BP glass as a separate item. From the F on the armor and BP glass was folded into the "armament provision" catagory. The guns (and some of their accessories ) were listed separate and the ammo was in another catagory.

Bombs under the wing often (all ?) times with restrictions on maneuvers and type/s of flying. They didn't have G meters so there was no use in telling the pilots not to exceed 4.5 Gs for example. Prohibiting inverted flight and any acrobatic maneuvers and a few other sentences were supposed to cover it.

It isn't just the weight that may have been added. Some aircraft had some growth in their airframe and normally he bigger aircraft could handle it better. It was also where the weight was added. The 109 when fitted with a couple of extra 20mm slung underneath the wings suffered a significant degradation in its handling and they were sometimes referred to as a 'barge'. The Spitfire went from 4 x LMG to 2 x 20mm in each wing and there was an impact in the climb but the handling was basically unaltered.
I don't think the 109 every carried more than a 500lb bomb but the Spit which was far from the best GA aircraft, often carried 1,000lb of bombs.

P-40s went from carrying I think 60 lb bombs on the outer wings to 250 lb and then 500 lb plus up to 1,000 lb on the centerline. Some were carrying three 1,000 lb bombs for short trips. They must have strengthened the wing a bit for that I would think. I think the real heavy bomb loads were with P-40N.

I wish W.E. Petter had been called off his Whirlwind concept in 1936 and instead been tasked with making a superlative single-engined, single-seat, wide undercarriage, folding wing, monoplane fighter for the FAA, likely Merlin-powered - to enter service alongside the Skua in autumn 1938, and canceling out the Fulmar, Sea Hurricane and Seafire.

This would have been a better contribution of Petter's talents than the deadend Whirlwind.

I can see the temptation there, though I suspect the problems with the FAA fighters had more to do with specs than anything else.

And I can tell you from experience, this is a journey fraught with many shoals, not to mention mines and torpedoes... maybe best to avoid that particular shipping lane.

Wild_Bill_Kelso said:

I can see the temptation there, though I suspect the problems with the FAA fighters had more to do with specs than anything else.

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Well, let's make the Whirlwind to a 1936 FAA spec instead of the RAF. Keep the twin Peregines, cannons, etc., but add a folded width of under 22ft (a challenge for a twin), greater internal fuel (in part through a radiator rethink), and new wing profile for slower takeoff and landing speed. Our revised FAA Whirlwind won't be hitting the 360 mph of the RAF's model, but we should be competitive.

I think that wing is too small with two engines on a carrier, I think the landing speed is too high, though I'll defer to others more knowledgeable on that subject.

Admiral Beez said:

and new wing profile for slower takeoff and landing speed.

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It is not the profile, it is wing loading. You are going to need something in the area of 300sq ft to handle the weight. Then we can worry about profile.
And please forget about slats. They only work at high angles of attack and trying to land nose high (or higher than were already using) is not a good plan.
Please remember that the F4U was designed to hold 273 US gallons in the wings and to have one .30 cal and one .50 in the fuselage and one .50 cal in each wing. granted it had the idiot anti aircraft bombs.

Petter also had a few faults as a designer. He tended to err on the side of speed/performance vs range/endurance (fuel capacity).
He also tended to be a little too innovative/tricky when he didn't need to be.

If you can't land or take off without unacceptable losses it doesn't matter how tricky you are with the wing fold.

Dimlee said:

Of the Bf 110. They just dropped the gunner and made the tail smaller because there was a deficit of materials.
I think I should put this on Wiki...

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It's a FACT! I read it on a very reputable website about WW2 aircraft.

Shortround6 said:

It is not the profile, it is wing loading. You are going to need something in the area of 300sq ft to handle the weight. Then we can worry about profile.
And please forget about slats. They only work at high angles of attack and trying to land nose high (or higher than were already using) is not a good plan.
Please remember that the F4U was designed to hold 273 US gallons in the wings and to have one .30 cal and one .50 in the fuselage and one .50 cal in each wing. granted it had the idiot anti aircraft bombs.

Petter also had a few faults as a designer. He tended to err on the side of speed/performance vs range/endurance (fuel capacity).
He also tended to be a little too innovative/tricky when he didn't need to be.

If you can't land or take off without unacceptable losses it doesn't matter how tricky you are with the wing fold.

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As per your post S Shortround6 re: Buffalo, its not just wing load, but airfoil profile (and Whirlwind really has issues with both)

You have to start with the RAE wind tunnel - it has 3 fundamental issues:
1. It isn't large enough to test the full size aircraft coming on line by mid 30s. And if you're using 1/5 scale models, your errors can be off by 5X.
2. It doesn't operate at high enough speed. Aerodynamists were extrapolating numbers from 100 mph to 400 which ignores Mach effects.
3. Flow in the wind tunnel was turbulent, not laminar. (Toyota had same issues when their F1 tunnel 1st came online - getting laminar flow in wind tunnel is challenge even today; as you have to realize there was an issue <you can't see it>.)

The result is you have designers believing there isn't much performance difference between mono and biplanes; really think airfoils are great (23021 in Welkin, 23017 in Whirlwind, Clark y - 19% Hurricane, 2219 - Typhoon - all cases wing roots), let alone highlight compressibility issues for a. propellers or b. fin/horizontal stabilizer. Once they realize they have an issue, they address it, but it didn't happen early enough.

Aside: That thick wing make life a whole lot easier for the structural engineer - strength being ~a cubic function of wing thickness. Packaging also becomes an issue - if you go down to equivalent to Spitfire 13% wing root airfoil, you need >3X the structural strength to achieve same result, at same time, your 8" diameter radiator can only be 6.5" diameter, so you need 5 radiators = 32" vs historic 24" with all the knock on effects. i.e. increased wingspan requires strength to increase as a quad function.

As a result, there is a whole lot of garbage in/garbage out. The fact that many of the airplanes performed as good as they did is a wonder.

Building a carrier twin is a true challenge, especially for FAA in mid 30s. While on the one hand, they would like top end performance equal to RAF fighters, they also want take off/landing performance the same as the Harts which they are currently operating. FAA compromised both Skua and Fulmar with slow speed/visibility requirements (If I was being asked to operate from HMS Argus/Hermes/Eagle, I'd be making same requests). So, 300 ft^2 isn't enough, you're probably looking at over 400 (weight is going to spiral as you increase wing area). Especially when you factor in that a twin needs to is suppose to be able to take off/landing above single engine minimum control speeds.

Almost doubling wing area is going to have very detrimental impact on top end speed even if we have improved airfoil

Shortround6 said:

It is not the profile, it is wing loading.

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By profile I should have said design, an entirely new wing, one optimized for good slow speed, fuel load maximization and wing fold, while not making it a total slug in combat.

The Whirlwind has a wing area of 250 sq ft (same as the IMAM Ro.57) less than 9 sq ft more of a significantly lighter Spitfire Mk.V. The USN's Grumman Skyrocket while smaller than the Whirlwind had a wing area of 303 sq ft, suggesting the direction the Whirlwind's wing needs to go. Would putting the Grumman XF5F or XP-50's larger wing on a Whirlwind wreck its performance? It seems a good place to start.

Perhaps start with the Tempest's wing?

41ft span and 302 sq ft wing area.

Put the engines where the main gear is supported.

You could probably use the Merlins too!

Admiral Beez said:

Would putting the Grumman XF5F or XP-50's larger wing on a Whirlwind wreck its performance? It seems a good place to start.

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It may not wreck it but it will degrade it. The question becomes how much.

The British had a problem in the late 30s, or several, but here they needed to figure out what they actually wanted the aircraft to do. And buy accordingly.

However they were facing a series of limitations.
Limited aviation fuel storage. Using twins will not help the situation.
Shortish flight decks. Low stalling speeds are called for, High wing load aircraft are going to be a problem.
Low endurance aircraft are problem, they spend a higher percentage of their time taking off and landing sucking up a higher percentage of the fuel.
Communications/navigation problems. In 1936/37 there is no radar, and no or poor fighter direction from a surface command center. And you have to deal with the expected radios of the time. What may show up in 2-3 years while the aircraft is under development can (and did) change but you couldn't count on it anymore that you can count on certain new features being on your 2025 cell phone.

This is aside from politics and even somewhat aside from some of the British air industries problems.
There may have been a reaction to spending too many years buying slightly warmed over models of 5-10 year old designs.
The pendulum swung the other way and they wanted new designs for every (or most) new problems/missions rather than trying make do with slightly modified old designs.
Trying to figure out what keep and what to replace early in the production cycle was hard.

The US got a little lucky and was able to spend some money on "concept" aircraft or perhaps proof of development. The F5F was delayed while Grumman worked on the F4F and because P & W dropped the the stage supercharger on the R-1535 engine and then the whole R-1535. The Navy did fund the Airabonita but it was a much to prove they were following the correct path and not missing out on the liquid cooled engine rather expecting to get a useable airplane out of it.
Us carriers carried a lot more aviation fuel than British carriers. and the small twin was done by the big single (F4U). A big twin (F7F) needed big carriers, the Midways or bigger.

Twin engined carrier fighter version / variant / derivative of Whirlwind seems very ambitious, though something better was certainly needed.

I'd have settled for a land based version. The X5F wing is an interesting point of comparison, this is basically what i was suggesting going back several pages.

Twins had a pretty damaging effect on aircraft numbers carried even on a 45,000 ton carrier like a Midway. These were the planned Air groups of the ship in 1947.

71xF4U + 40xAM-1 + 4xAEW Skyraiders.
OR
40xF7F + 4xAEW Skyraiders.

Both the AM-1 and F7F had a wingspan of about 50 feet but the latter was about 4 feet longer. The real difference is in folded width.

In 1940 the Spec for a new naval fighter called for a folded width of 13ft 6in. That target was met in the Fairey Firefly, Blackburn Firebrand F.I (but not the later TF versions) and Seafire III/XV/XVII. That allowed 4 abreast stowage in the 62 foot wide armoured carrier hangar. How will your naval Whirlwind development compare?

X5F looks like it may have made a pretty good land based fighter.

Wild_Bill_Kelso said:

X5F looks like it may have made a pretty good land based fighter.

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The land based proposal

Wild_Bill_Kelso said:

X5F looks like it may have made a pretty good land based fighter.

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Imagine a squadron or two at Pearl Harbour. They'd get to altitude in record time. As for suitability for naval ops, the X5F and its successor, the Grumman XP-50 seem good for the task. Folding wings, robust construction, and adequate performance. What's not to like? Put this wing and fold onto the Whirlwind and let's see what we get.

Shortround6 said:

It may not wreck it but it will degrade it. The question becomes how much.

The British had a problem in the late 30s, or several, but here they needed to figure out what they actually wanted the aircraft to do. And buy accordingly.

However they were facing a series of limitations.
Limited aviation fuel storage. Using twins will not help the situation.
Shortish flight decks. Low stalling speeds are called for, High wing load aircraft are going to be a problem.
Low endurance aircraft are problem, they spend a higher percentage of their time taking off and landing sucking up a higher percentage of the fuel.
Communications/navigation problems. In 1936/37 there is no radar, and no or poor fighter direction from a surface command center. And you have to deal with the expected radios of the time. What may show up in 2-3 years while the aircraft is under development can (and did) change but you couldn't count on it anymore that you can count on certain new features being on your 2025 cell phone.

This is aside from politics and even somewhat aside from some of the British air industries problems.
There may have been a reaction to spending too many years buying slightly warmed over models of 5-10 year old designs.
The pendulum swung the other way and they wanted new designs for every (or most) new problems/missions rather than trying make do with slightly modified old designs.
Trying to figure out what keep and what to replace early in the production cycle was hard.

The US got a little lucky and was able to spend some money on "concept" aircraft or perhaps proof of development. The F5F was delayed while Grumman worked on the F4F and because P & W dropped the the stage supercharger on the R-1535 engine and then the whole R-1535. The Navy did fund the Airabonita but it was a much to prove they were following the correct path and not missing out on the liquid cooled engine rather expecting to get a useable airplane out of it.
Us carriers carried a lot more aviation fuel than British carriers. and the small twin was done by the big single (F4U). A big twin (F7F) needed big carriers, the Midways or bigger.

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And the US had the advantage of foriegn governments purchasing good aircraft that the US forces were ignoring or slowly evaluating and even buying brilliant new designs straight off the drawing board - eg Mustang

MiTasol said:

And the US had the advantage of foriegn governments purchasing good aircraft that the US forces were ignoring or slowly evaluating and even buying brilliant new designs straight off the drawing board - eg Mustang

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When the Japanese attacked Pearl Harbor The US said to the British "those Mustangs will be staying here"