Dive-bombing Me 110?

tomo pauk said:

The power of the AM 37 should be 1450 CV for take off, 1300 CV at SL (nominal regime) and 1400 CV at ~5.8 km (also nominal). The AM 35 A was, respectively, at 1350, 1120 and 1200 CV at 6 km. The MiG 5 was a substantial aircraft, almost 39 sq m of wing area (some 30% greater than of P-38, just some 7-8% less than Mosquito), and with two AM 35A would not perform as wanted, we'd have maybe 580 km/h?

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I'd think the loss in acceleration and climb (assuming no additional reductions in weight beyond engine/radiator) would be more significant.

We discussed before the possible compromises between the AM35 and AM37 in terms of getting a functional engine into mass production (implementation of an intercooler similar to the AM37's on the AM35 seems to have been the best suggestion). An AM35A powered MiG 5 would perhaps mostly be useful as an interim design if production/preproduction was actually moved forward with early war (say if the Soviet industrial relocation hadn't occurred -or had been delayed) with more powerful engined versions following. (at very least if it reached production before the AM38 was available in quantity -otherwise starting production with the AM38 would make more sense followed by an intercooled AM35 derivative ... which might perform better than the AM38 at all but very low altitudes as well, albeit with some intercooler drag)

Just using a 2-speed supercharger allowing gearing switched between the speeds used on the AM35A and AM38 would probably be simpler and offer a smoother power curve. (except given Mikulin ended up sticking with single speed superchargers for so long, was already working with intercooling, and adapting an intercooler to the AM35A would mean rerouting ducting between the supercharger and carburetors but not making major changes to the engine structure, it might actually be faster/more efficient to implement that)

I suppose introducing a supercharger gear ratio intermediate from the AM35A and AM38 would also be notable and possibly the simplest and most foolproof option. A critical altitude more in the 3-4 km range would probably be quite useful.

This is where the 'substantial' stature of the MiG 5 is a good thing - big wing will help out with taking off with big payload in a fighter-bomber role.

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I haven't seen figures for the airfoil thickness:chord on the MiG-5, but given the broad chord and somewhat low aspect ratio, it seems possibly they adopted a fairly thin (and thus low drag -and lower lift) airfoil section). The leading edge taper/sweepback might have some impact on that as well. I know a Clark YH airfoil section was used (so not ideal but improved from the simpler Clark Y at least), but that says nothing about the thickness.

Mind you, given the existing flight testing with the AM37, the 580 km/h estimate for the AM35A seems fairly reasonable regardless. (a thinner wing would point to better potential for higher speeds in general with more power, higher critical mach number, and greater potential dive performance)

GregP said:

It doesn't matter whose fault it was. You get one shot at greatness and the Whirlwind didn't make it....... It had potential that lack of a good engine with development possibilities made moot.

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Exactly, plus two engines to lift four cannon when the Air Ministry was expecting a single engine aircraft from Hawker to do the same was never going to cut it with the bean counters at the Ministry. It also used considerably more other resources than contemporary single engine types.

There are similarities with Germany's Fw 187 programme, but the British decisions were much more rational.

Cheers

Steve

Do we actually know the price of the Whirly vs. price of the Typhoon? The contemporary S/E types were under-performers when carrying 4 cannons, so the comparison of the resources spent does not look like a fair one. We also have the Defiant - half of the firepower and twice the crew than other S/E fighters, plus less performance.
Some British decisions about what to purchase or not were more rational than the others, just like what happened with other countries.

kool kitty89 said:

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Just using a 2-speed supercharger allowing gearing switched between the speeds used on the AM35A and AM38 would probably be simpler and offer a smoother power curve. (except given Mikulin ended up sticking with single speed superchargers for so long, was already working with intercooling, and adapting an intercooler to the AM35A would mean rerouting ducting between the supercharger and carburetors but not making major changes to the engine structure, it might actually be faster/more efficient to implement that)

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The intercooler was located between S/C and carbs on the AM 37, while using the engine coolant for it to function - one needs greater capacity of the cooling system, or engine will overheat. The 2-speed AM engine should be a great asset.

I suppose introducing a supercharger gear ratio intermediate from the AM35A and AM38 would also be notable and possibly the simplest and most foolproof option. A critical altitude more in the 3-4 km range would probably be quite useful.

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Agreed all the way. We'd see the rated power of 1400-1300 CV for that range of rated altitudes. Then there is an option of over-boosting the engine, along with over-revving AND over-boosting (like it was implemented in the AM-38F and AM 42).

tomo pauk said:

Do we actually know the price of the Whirly vs. price of the Typhoon? The contemporary S/E types were under-performers when carrying 4 cannons, so the comparison of the resources spent does not look like a fair one.

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It's been covered elsewhere. The resources issue was one of the several reasons cited for the cancellation of the Whirlwind by the decision makers at the time.

The four cannon Hawker fighter, which became the Typhoon, was expected sooner than was historically the case. By 1940 Spitfires were making tentative and not always successful steps on the road to mounting cannon armament and soon thereafter a mixed cannon-machine gun armament became standard on that type. By late 1940 the Defiant became obsolete in a day time role, it and turret fighters generally were an interesting, but ultimately fruitless dead end. They served with Fighter Command, at the sharp end, for less than one year. It's always amazed me that enough other uses were found for it to continue production into 1943! As Dowding later wrote, before giving an accurate and succinct summary of the Defiant's failings (as a day fighter/bomber destroyer) "I think it is now generally agreed that the single seater multi-gun fighter with fixed guns was the most efficient type which could have been produced for day fighting." This also rules out the Whirlwind in that role.

Cheers

Steve

I am not sure how? "I think it is now generally agreed that the single seater multi-gun fighter with fixed guns was the most efficient type which could have been produced for day fighting."

No mention of number of engines and the Whirlwind sure meets the bolded part

Shortround6 said:

I am not sure how? "I think it is now generally agreed that the single seater multi-gun fighter with fixed guns was the most efficient type which could have been produced for day fighting."

No mention of number of engines and the Whirlwind sure meets the bolded part

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Yep, my bad

Steve

stona said:

It's been covered elsewhere. The resources issue was one of the several reasons cited for the cancellation of the Whirlwind by the decision makers at the time.

The four cannon Hawker fighter, which became the Typhoon, was expected sooner than was historically the case.

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I'm not sure that we ever had the price of the Whirly and Typhoon stated on this forum. Correction welcomed, of course.

...
As Dowding later wrote, before giving an accurate and succinct summary of the Defiant's failings (as a day fighter/bomber destroyer) "I think it is now generally agreed that the single seater multi-gun fighter with fixed guns was the most efficient type which could have been produced for day fighting." This also rules out the Whirlwind in that role.

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As SR6 noted above - the Whirly fits there

GregP said:

Almost any warplane can be a limited dive bomber. That is, you can add a bombs or bombs, climb to some preferred height, roll or push over and dive at a target, release the bomb, and pull out. To be a good dive bomber you have to be able to aim pretty accurately at the target and hold the dive long enough to do that function.

The Bf 110 was VERY adaptable and could certainly carry a bomb and dive at a target and release the bomb. But it would soon gain enough speed to render pulling out questionable and the accuracy achieved was not good. It could not stay in a steep dive for long and the pilot would have to dive, acquire the sight picture, pickle, and pull out before exceeding Vne. For any sustained use, it would have had to be redesigned with sustained dive speed control, dive bombing strength, sights, and some other dive bombing considerations in place. The result, while possibly resembling a Bf 110, would probably not be able to be built on the same assembly line.

So I'd say you could use the Bf 110 in a pinch if nothing else was avialable, and you might scare the hell out of a few guys. But you wouldn't get typical dive bombing type results and you might lose a plane or two in the process just from the pilots not being familiar with dive bombing and the plane not being streed for it. You would be much better off, if you HAD to use the Bf 110 as a bomber, using it as a level bomber or as a bomber from a shallow dive angle. That, at least, isn't far out of the specifications of the airframe.

The Mosquito was designed as a fast, unarmed bomber. It was adaptable enough to wind up as that fast, unarmed bomer ... an armed fighter, a recon plane, a pathfinder, and even a night fighter with a circular, segmented speed brake mounted all round the fuselage. It probably could have had the speed brake made larger for use as a dive bomber, but the UK already HAD dive bombers. So did Germany.

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I agree with this. Really, you can rig just about any fighter for dive-bombing. Give the pilots training, they'll figure out how to get it done. The thing about the dive-bombers is, well, they were dive-bombers. They had all the advantages, designed-in. Doesn't mean they were all the same, just as the fighters weren't all the same. Different priorities, philosophical differences, those showed. The SBD couldn't dive the way the JU87 could. Or, it could, but it doesn't want to. The JU87 was a bullet, and that's the way they wanted it. As far as I know, it wasn't broken, either, so why try to better it? It was doing what they were asking.

VBF-13 said:

The thing about the dive-bombers is, well, they were dive-bombers. They had all the advantages, designed-in.

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They also had all the disadvantages designed in too. The Ju 87 and other purpose built dive bombers was terribly vulnerable to fighters. The British estimated the Ju 87 to be most vulnerable whilst re-forming after an attack. Most could only operate effectively against a well organised defence in areas where at least temporary, local air superiority had been established.
Something like the Me 210 was supposed to be able to dive bomb and be able to defend itself as, for examples, the P-47, Fw 190 F and Typhoon, which are all of course fighter-bombers rather than purpose built dive bombers,could.

Cheers

Steve

I was under the impression that rockets were developed in part so you didnt have to fly over or dive onto a target. Dive bombing anything with an anti aircraft defence is asking for trouble.

stona said:

They also had all the disadvantages designed in too. The Ju 87 and other purpose built dive bombers was terribly vulnerable to fighters. The British estimated the Ju 87 to be most vulnerable whilst re-forming after an attack. Most could only operate effectively against a well organised defence in areas where at least temporary, local air superiority had been established.
Something like the Me 210 was supposed to be able to dive bomb and be able to defend itself as, for examples, the P-47, Fw 190 F and Typhoon, which are all of course fighter-bombers rather than purpose built dive bombers,could.

Cheers

Steve

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Well, sure enough. But are you making a bomber, or a fighter? Are you making an SBD, or an F4F? Or an F6F, which would have put both those out of business.

VBF-13 said:

Well, sure enough. But are you making a bomber, or a fighter?

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Well, before the war the dive bomber was being built as a bomber. It's vulnerability made it unsustainable. I'm not sure how many purpose built dive bombers were still operational in 1945. There were plenty of fighter-bombers.

Cheers

Steve

stona said:

Well, before the war the dive bomber was being built as a bomber. It's vulnerability made it unsustainable. I'm not sure how many purpose built dive bombers were still operational in 1945. There were plenty of fighter-bombers.

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This very issue came up in another discussion (I forget, but it may have been the Fw 187/fighter-bomber thread). It was pointed out that purpose-built dive bombers existed for a relatively narrow period of time from the late 1930s to early 1940s. Prior to that, most dive bombing was done by bomb-carrying fighters (fighter bombers) and it appears the transition from biplane to monoplane fighters at least in part led to the divergence of the two. (Ernst Udet himself started initial dive bombing build-up with export versions of the Curtiss F11C Goshawk fighter)

Granted, monoplane wise pre-war you DID technically have the Skua being a capable dive bomber and 'fighter' ... but it really wasn't much of a fighter for its time. In fact, most of the late generation biplane fighters were still bomb-capable pre-war: the I-15, F3F, CR.42, and even the B-534 and Ar 68 carried small bombs (granted, the P-40 initially had provisions for such as did some P-36 models and the P-35). Britain seems the odd one out with the Gladiator and Fury not aimed at bombing ability. (might have made the Sea Gladiator a good be more useful, possibly more heavily displacing the Skua as well -they did use similar engines after all, and the Gladiator was faster, far more maneuverable, and generally less vulnerable to enemy fighters ... and more useful as a fighter; upgrading to a variable pitch prop would help too)

In the inter war years 'Imperial air policing' was generally carried out against people who had no or extremely limited anti aircraft capability and no air force of their own. It was an effective and, crucially, cheap method of policing the Empire because it was effectively uncontested. It could be carried out by any aircraft that could lift the small loads required to destroy some unfortunate chieftain's kraal or whatever. Survivability was not an issue for the RAF.
Cheers
Steve

The whole "idea" behind dive bombing was to dive as steeply as possible so after the bomb left the aircraft it would have the least horizontal distance to travel before hitting the ground.
This was one contribution to accuracy.
Another was the time it gave the pilot to aim and the much reduced ground speed of the aircraft. Lets for the sake of argument/illustration assume our 'bomber' can fly and hold the speed of 200mph regardless of dive angle.

Flying horizontally it is covering 300feet per second and an error of 1/10 of second in bomb release is a "miss" of 30 ft.
Doing a 30 degree dive reduces the ground speed to 260fps an error of 1/10 of second in bomb release is a "miss" of 26ft.
A 45 degree dive reduces the ground speed to 212fps an error of 1/10 of second in bomb release is a "miss" of 21.2ft.
A 60 degree dive reduces the ground speed to 150fps an error of 1/10 of second in bomb release is a "miss" of 15ft.
An 80 degree dive reduces the ground speed to 52fps an error of 1/10 of second in bomb release is a "miss" of 5.2ft.

Obviously diving at 80 degrees or above provides great accuracy. Very few aircraft can actually dive at 90 degrees. The plane may have a 90 degree attitude but the wings are still trying to provide "lift" which in this case pushes the plane "upward" or displaces the plane from the desired flight path. The above "assumes" a 100% accurate airspeed indicator. Absolute calm (no tail wind or head wind) and a few other things that were never going to happen.

The near vertical flight path also gave the pilot a number of seconds to line up and correct aim that the level pilot (or shallow dive attack) didn't have. It also eliminated trajectory problems due to height errors (is that 5,000ft on the altimeter really 5000ft or is 4900ft or 5100ft?

Those were some of the initial attractions. It also helped that up until 1940-41 most armies had crap for AA weapons. A British Battalion had FOUR Bren guns on AA mountings on a permanent basis. The US tables of organization showed BAR's on AA mounts for vehicle defense (.50 cal MGs were still sharing Anti-tank duties) and so on.

However we can see a few problems with trying to use fighters as dive bombers. Once you go to monoplanes with retracting landing gear the fighters simply dive too fast, they don't have the time to aim and steady on course like a true dive bomber with dive brakes. They also have to start pulling out at a higher altitude because of the greater speed.
AS for "true" dive bombers. Once Armies started issuing multiple mg mounts (quad mgs) for AA and large numbers of .50 guns or 20mm cannon or larger (British 1943 Division had 16 20mm guns per brigade and 54 40mm guns in the AA Regiment, with or without extra 20mm guns), attacking ground troops got a whole more dangerous even without enemy fighters.

Air forces went for fighter bombers with their reduced accuracy but greater survivabilty.

stona said:

Well, before the war the dive bomber was being built as a bomber. It's vulnerability made it unsustainable. I'm not sure how many purpose built dive bombers were still operational in 1945. There were plenty of fighter-bombers.

Cheers

Steve

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The F6F and F4U could do it all. People don't credit them enough for that.

Shortround6 said:

A 60 degree dive reduces the ground speed to 150fps an error of 1/10 of second in bomb release is a "miss" of 15ft.

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Our SBD pilots were hitting die markers in the Gulf and the Atlantic at a rate of 4-for-5 and 5-for-5 on radio-monitored 60-degree dives. That's good enough.

"Steep, fast and press!" The words of my bombing instructor at Lead In Fighter Training. Or they were called Tiger errors. Steeper, faster, and going below pickle altitude all resulted in smaller errors than their mirror equivalent in the opposite direction. The steeper the better, less errors due to less variables (aka Stuka attack).

Cheers,
Biff

Shortround6 said:

Obviously diving at 80 degrees or above provides great accuracy. Very few aircraft can actually dive at 90 degrees. The plane may have a 90 degree attitude but the wings are still trying to provide "lift" which in this case pushes the plane "upward" or displaces the plane from the desired flight path. The above "assumes" a 100% accurate airspeed indicator. Absolute calm (no tail wind or head wind) and a few other things that were never going to happen.

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Wouldn't use of dive breaks also designed with spoiler aerodynamic effect help get closer to a true 90 degree dive? (that and/or using a symmetrical airfoil for the wing profile resulting in -theoretically- zero lift at zero AoA)

However we can see a few problems with trying to use fighters as dive bombers. Once you go to monoplanes with retracting landing gear the fighters simply dive too fast, they don't have the time to aim and steady on course like a true dive bomber with dive brakes. They also have to start pulling out at a higher altitude because of the greater speed.

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Yes, you need dive breaks or landing gear designed to operate at high speeds (like the F4U), or both.

Though the Hurricane's large wing area and thick airfoil might have worked decently well to slow the dive as well. Spitfire, 109, and P-36/P-40 not so much. (though the R-1820 powered hawks might have had enough drag to get by, at least better than the Spit or especially 109)

If the Germans wanted a dive-bomb capable 109, the larger 109T wing combined with dive breaks or strengthened landing gear might have worked. (higher drag of the 109E/T airframe over the streamlined F series would be a benefit here too) It'd really need a fuel capacity increase too though. (either wing tanks or a rear fuselage tank, possibly ballasted by increased engine/nose armor)


I still think it's odd that Udent put so much emphasis on turning level bombers into dive bombers, but not putting the same (let alone greater) emphasis on making fighters dive-bomb capable.

The Vultee Vengeance was designed to do 90 degree dives. Part of it was putting the wing at either 0 degrees incidence to the fuselage or few negative degrees. Sort of a reverse Whitley. It flew slightly nose up in level flight. Not a big deal until you go to land. Wacking big radial engine sticking up even more than on other planes.

A Hurricane could get to over 400mph in a dive, perhaps not as quick as some other planes but nobody really wants to be dive bombing at 400mph +.

Udet's Curtiss Hawk


photo of a Hawk


Even a Hawk 75 with a Cyclone 9 (same size as the engine in the above planes) isn't going to be enough to slow the monoplane compared to the bi-plane with it's fixed gear, struts and wires. Most bi-planes didn't need dive brakes.