Dive bomber for 1940: how would you do it

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I'd go with the Northrop XBT-2, otherwise known as the SBD-1. It was an effective long range dive bomber. And while, like all other dive bombers, it needed air protection, when cleaned up it was feisty and was not an easy morsel for enemy fighters.

I don't know any changes I would make except maybe put in the 2600 engine, which would make it nose heavy. Maybe have a big dude fly in aft cockpit.
 
One of early fighters that was known as sturdy was P-40. With air brakes, akin of what A-36 had, and two 500 lbs bombs, it seems good on paper. We even have a centerline pylon free for drop tank, leaving 500 airframes available for P-51 production right when it's needed.

As for adapting Dauntless to carry R-2600, guess that would've make less issues than development of SB2C

If someone can share some good info about how good was A-36 when subjected to repeated pull-outs at high Gs, then please do so
 
Something to consider is what the tactical thinking of the day was. I like the idea of the hs 123 but we have to consider what the goal of the dive bomber was.

A naval dive bomber was supposed to sink ships, it's window of opportunity was fleeting. Army dive bombers when flying close support also had limited time frames in which to work. They either had to take out artillery concentrations or troop concentrations, strong points or bridges or attack choke points. The battle and targets changed with time. You may be able to slow down or stop an attacker by blowing a few bridges. A couple of days later the attacker may have many more in his possession. Naval formations move by the hour.

2 seat dive bombers may have been intended to fight their way to the target while still carrying the bomb load. A single seater may be able to defend itself better but only after jettisoning the bomb/s which is a mission kill for the defender. Even if they don't shoot down a single attacking single seater, the single seaters have to return to base, rearm and refuel and depending on range and time of day wait another day. The Naval ships will be someplace else if they are at sea and even army targets can change location. The bridges will still be there but with how many hours more traffic across them?

I will grant that the two seaters in practice couldn't defend themselves very well at all at times and ideally both types of dive bomber needed escorts.
 


I dont know this extract from your last post is necessarily true. by 1941, bot the US and britain were working on designs for attack planes that were intended to be resistant to the fighters of the day. In the case of the US it was the A4D Skyraider series, and prior to that the relatively unsuccessful BTD prototype. In the case of the brits it was a somewhat hybrid design, the Fairey Firefly. Both these aircraft were fast , well armed, and either were, or would have, been capable of operating in hostile environments with relatively little fighter escort. In part, their repective post war careers was made possible by this relatively high performanmce, even when fully loaded, their high level of survivability, and their relatively heavy defensive armament.

The japanese were also working on a solution to the vulnerability of their attack types, which culminated in two types worth mentioning. firstly there was the b-7 grace attack plane, which was lightly armed in terms defensive armament, but was a hot performer. This concept was even further explored by the c-7 Myrt. both types had improved passive defence systems compared to theiur immediate predecessors, but relied on exceptional performance mostly to keep them out of trouble.

These concept of uninterceptable, or defendable attack aircraft were probably were beyonfd the technology available in 1940. Fighter performance was generally behind bomber performance in the early 1930s, but by the late 1930s, fighter performance had shot by the performance of their prey. In the early 1940s, fighters continued to be developed, but I think the performance of bombers increased at a greater rate than that of fighters, until about 1944 at any rate
 

I believe their post war careers were made possible by their operating in conditions of almost total air supremacy. If the enemy can't put aircraft into the air or can't put them into the air in effective numbers then escort for the bomber/strike aircraft aren't needed. While there are the incidences of Skyraiders shooting down Migs, did they do it while carrying 2,000-4,000lbs of under wing ordnance? Even with four 20mm cannon in the wings the Firefly's chances of survival would be slim if bounced (intercepted) by equal numbers of LA-7 or LA-9 fighters if the elected to keep the underwing loads on the aircraft.


In the case of the Grace the same thing applies. While it's top speed makes interception difficult for defending fighters that top speed is without the external torpedo. Internal bomb bay load might have affected speed less but climb and turn are both going to suffer if the bomb load is kept making the use of the wing mounted 20mm cannon rather difficult. Lets face it, the Grace used the same engine as the George and was about 3000lbs heavier, even with good streamlining it was going to have trouble in a dog fight and keeping 800KG inside the bomb bay during said dog fight wasn't going to help. The Myrt was recon plane, no bombload.

Not really, given similar engines, the fighter is always going to have the advantage. Now when comparing aircraft, some countries progress did not always keep pace with another countries and even in the same country, different programs did not always keep pace with each other even if started at the same time.
 
in the context of this discussion, ie, the ideal D/B for 1940, i think you are correct. however, in the following generations of strike aircraft, this becomes less and less true (that is, as a fully loaded aircraft their performance suffered markedly). To try and illustrate this point, consider the effects on an aircraft like an f-111. What impact does a full load of ordinance have on this aircraft, obviously some, but not nearly so much as the lumbering bombers of 1938-40. The bombload, as a factor in the performance arc of an aircraft capable of 1500 mph is not a significant factor.

Now, the question arising from this is what effect the bombload would have on the next generation following the 1940 group of designs. Whilst it is going to be a lot more than the effect on a supersonic bomber, its still going to be less than the underpowered machines of 1940.

now in the case of an aircraft like the firefly, its background reduces this effect even more. The firefly was designed from the start to be a multi-role aircraft, specifically it was designed as a fighter/lr recon machine. Quite early this dual role was expanded to include strike functions, as well as a whole range of specialised functions including NF and ASW aircraft. However, as a fighter /recon, it had a combat radius of about 1300 NM. As a strike aircraft it had a combat radius of about 500 NM when carrying its full payload. Clearly the fighter/recon version was intended to carry fuel instead of bombs, and a lot of it. Fully loaded, as a fighter the mk IV was expected to have a speed in excess of 380 knots. To be honest, i am not exactly sure what its peformance was when operating in a non-fighter capacity, but some of the old timers I talked to years ago simply said, when asked this very question by me, was essentially there was not much difference in the performance of the fighter version and the bomber version, in terms of speed at least.

so, in the context of our 1940 problem, we need to reduce payloads so that airspeed is not so fatally affected. If the strike speed is kept up, even by a few MPH, then the interception issue becomes that much harder....youd be surprised i think how much difference just a few MPH would make to the vulnerability issue
 

I am afraid you are comparing apples to oranges here and the F-111 is a particularly bad example. It is a plane that went over 47,000lbs empty in early versions (later ones got heavier?) it could carry TWO 750lbs bombs internally and wither or not they were carried would make little difference to the planes performance so you are correct in that sense. However it's "full load of ordinance" of an additional FOURTY EIGHT 750lbs bombs meant that the wings could not be swept past 26 degrees. The plane was defiantly limited to sub-sonic speeds in this case. Even while carrying Twenty Six 750lb bombs the wing sweep was limited to 54 degrees, not the full 72 degrees.
Most Mach 2 Jets that carry underwing ordnance become sub sonic due the the drag of the underwing stores, let alone limiting their wing sweep.
The other major user of the TF-30 engine was the F-14 Tomcat as a comparison of of bomber to a fighter using the same engines.



I guess it depends on how you measure the performance: As a fighter/recon plane the plane was carrying drop tanks to get that 1300 mile range. Can you please find a reference for that 380kts speed even while clean?
Most sources give speeds of about 386mph for a MK IV.
I can certainly understand a plane performing about the same while carrying either bombs or drop tanks but don't tell me it performs the same with underwing stores as without.

There were only about 120 MK IVs built.
The MKs 5, 6 and 7 while the had wing guns and attachment points for under wing loads also had a radar scanner in a pod under the starboard wing and fuel tank to balance it under the port wing, this was in addition (instead of ?) to possible under wing loads like bombs or rockets.
Range for a MK 7 three seat radar trainer is given as 860 miles at 166 mph at 5,000ft at full load in the 1954-55 Edition of "Jane's"


While a few MPH can certainly make the interception problem more difficult for the defender and so reduce "vulnerability" in the sense of getting the interceptors to the same patch of sky (within a few miles and at a suitable altitude), if that has been achieved then a few MPH more (10-20mph) is going to make little difference to the survivability of a dive bomber. Top speed of a SBD-5 is given as 255mph, getting it up to 275 against a 330mph Zero buys you what once the panes are within a mile or two of each other? the Zero can cover the distance in 1-2 minutes.
 

I guess there these dive brakes would have come in handy I also seem to remember the zero model 63 (a6m7) that was designed to be used as a dive bomber. The zero wasn't the fasted diver in the inventory but it was also not the sturdiest
 
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I am afraid you are comparing apples to oranges here and the F-111 is a particularly bad example. It is a plane that went over 47,000lbs empty in early versions (later ones got heavier?) it could carry TWO 750lbs bombs internally and wither or not they were carried would make little difference to the planes performance so you are correct in that sense. However it's "full load of ordinance" of an additional FOURTY EIGHT 750lbs bombs meant that the wings could not be swept past 26 degrees. The plane was defiantly limited to sub-sonic speeds in this case. Even while carrying Twenty Six 750lb bombs the wing sweep was limited to 54 degrees, not the full 72 degrees.
Most Mach 2 Jets that carry underwing ordnance become sub sonic due the the drag of the underwing stores, let alone limiting their wing sweep.
The other major user of the TF-30 engine was the F-14 Tomcat as a comparison of of bomber to a fighter using the same engines.

I believe now you are being dliberately obtuse.....the reason i raised the F-111 was not as any sort comparison, it was as an extrapolation, to underline the point that with increasing engine power the effect of airframe mass become less and less relevant.

I guess the US and Australian experiences with the F-111 are fundamentally different. The Australians AFAIK never loaded the aircraft up with 48x 750lb bombs. This may have something to do with its different role in the Australian defence framework. They were principally maritime strike, which from late '78 onward meant thy typically carried two or four AGM-84 missiles. I recall at one excercise our radar clocked one of these aircraft carrying such a load travelling on the deck at 1320 knots. If we assume 4 x missiles as the loadout, thats about 4000lbs of ordinance. At that speed not even the Tomcats of the USN could not effectively interecept, could not lock on and could not really engage in standoff attacks. the aircraft was un-interceptable, in the environment that it was working in, that is, flying very fast, very low





I guess it depends on how you measure the performance: As a fighter/recon plane the plane was carrying drop tanks to get that 1300 mile range. Can you please find a reference for that 380kts speed even while clean?
Most sources give speeds of about 386mph for a MK IV.
I can certainly understand a plane performing about the same while carrying either bombs or drop tanks but don't tell me it performs the same with underwing stores as without.

Its design spec was to operate at a certain speed at a certain range. I dont know it was using drop tanks or internal fuel to achieve that range, but the speed spec was a given. if the aircraft could not operate at that speed, at the range given, then the design was not meeting the spec. Getting to the target is a different matter, typically all aircraft, including fighters used to vector out to intercept an incoming strike will travel at a lot less than the design speed whilst in transit. I dont have figures to prove that the firefly could travel at 380 knots whilst at 1300 miles range, but one could reasonably expect it to, otherwise it was not meeting the design spec.

There were only about 120 MK IVs built.
The MKs 5, 6 and 7 while the had wing guns and attachment points for under wing loads also had a radar scanner in a pod under the starboard wing and fuel tank to balance it under the port wing, this was in addition (instead of ?) to possible under wing loads like bombs or rockets.
Range for a MK 7 three seat radar trainer is given as 860 miles at 166 mph at 5,000ft at full load in the 1954-55 Edition of "Jane's"

I only specified the Mk IV because it represented the last mixed fighter/recon version. thereafter the design ceased to be a true fighter, and increasingly became a strike aircraft, with a lot less emphasis on performance.


While a few MPH can certainly make the interception problem more difficult for the defender and so reduce "vulnerability" in the sense of getting the interceptors to the same patch of sky (within a few miles and at a suitable altitude), if that has been achieved then a few MPH more (10-20mph) is going to make little difference to the survivability of a dive bomber. Top speed of a SBD-5 is given as 255mph, getting it up to 275 against a 330mph Zero buys you what once the panes are within a mile or two of each other? the Zero can cover the distance in 1-2 minutes.

Picking zeroes is a poor choice because of the lack of radar, which meant Japanese CAP tended to remain within sight of the carrier they were defending. However in the case of the Allies, CAP was often called upon to vector out to a certain range to intercept one strike, and then might be called upon to rush to the other side of the air defence zone to deal with another threat coming from a different direction. If the the atackers are travelling say 30 knots faster (280knots as opposed to 250 knots) and the interceptors have a max speed of 340 knots, but because of endurance issues can only travel at say 320 knots max, and the new bogey is picked up at say 50 miles out, and the angels are also 50 miles out, on the other side of the zone, then this additional 30 knots spped for the attackers makes a huge difference. To cover that 50 mile range, the flight time is reduced from 12 minutes to 10.7 mins. In the meantime the the I calculate the engagement time for the vectored interceptors is reduced from a little over 158 secs to about 80 seconds, give or take. Thats a massive reduction in firing time, moreover its a typical scenario that defending fighters would find themselves in whether they be protecting a land or sea target.

Of course there are endless permutations to that relationship. It depends on the availability and positions of the fighters relative to both the target and the attacking force. It depends on the relative skill of the pilots concerned. how long does it take for the interceptors to achieve a satisfactory firing solution? A additional 30 knots of speed gives the attackers a harder target and conditions for this to be achieved....the slower the target, the harder it is to put into a corner in the sky, and the less time for that solution to be achieved. I think you are significantly underestimating the value of speed in adding to the defensive abilities of the strike group.
 
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I think I will continue to be obtuse. Extrapolating 30 years into the future is really pushing things and while I admit to pushing the envelope with your "full" load definition some of your information seems a little suspect.

Gee, 1320 knots on the deck. And with an under wing load too. Guess I was wrong. I wonder why we ever gave that plane up. Isn't 1320 knots 1518mph? Now 1320 Kilometers per hour is 818mph which is a lot more believable. Either that or must published soources on the F-111 are way off, It it could do 1518mph on the deck I wonder what it could do at altitude? With a published top speed of 1453mph at 53,400ft but a secret 600mph in hand it could probably outrun an SR-71


Now you are either being obtuse or deliberately baiting me. Knots are not the same as mph. Knots are 1.15 times MPH so 380knots would be 437mph. Congratulations!!! we now have a Firefly that can outrun a Mustang and do it while carrying a pair of 1000bs bombs under the wing.

No WW II aircraft was speced at range with maximum speed. The Speed may be specified and the range at a suitable cruising speed may be specified but claiming the the Firefly was "speced" to fly 1300 miles at 380kts is pure hocum. That or it is fueled by Fosters.
 
I think I will continue to be obtuse. Extrapolating 30 years into the future is really pushing things and while I admit to pushing the envelope with your "full" load definition some of your information seems a little suspect.

Do you agree that with increasing engine power, or perhaps more correctly with increaing power to weight, the effect of mass has a decreasing effect on maximum speed. I'll put it in these terms....velocity of a weighted object is a function of its Kinetic Energy. Kinetic energy is equal to the objects mass, multiplied by its velocity squared. Therefore, as the velocity increases even a little increases its required Ke by a lot, whereas, increasing its mass has a lot less effect.



Gee, 1320 knots on the deck. And with an under wing load too. Guess I was wrong. I wonder why we ever gave that plane up. Isn't 1320 knots 1518mph? Now 1320 Kilometers per hour is 818mph which is a lot more believable. Either that or must published soources on the F-111 are way off, It it could do 1518mph on the deck I wonder what it could do at altitude? With a published top speed of 1453mph at 53,400ft but a secret 600mph in hand it could probably outrun an SR-71

You are right, I should have said 1320 mph. Dont take my word for it, obviously you dont, if you can locate the after action reports for RIMPAC 78 you will find the evidence there. I notice that by trying to deflect the argument away from the key issue that sparked this debate in the first place, you have failed to even respond to the salient argument.....that speed affects the ability to intercept a target. you have not tried to refute the arguments, firstly that F-11s could travel at that speed with that loadout, and secondly that at that speed, they were basically un-interceptable. Instead, we have this argument developed about knots versus MPH. To me thats irrelevant to the argument. question is, what is the main determinats of airspeed, and secondly, with increases in airspeed, does that not make it difficult to intercept. You seem to be saying that bombs reduce all strike aircraft to airspeeds where they are easily intercepted, and secondly that mass is the major detrminant of airspeed. Intersting position...i guess you have never looked at Mosquito operations all that carefully, or wondered why B-26 operations had the lowest loss rate of any US bomber during the war.....



Now you are either being obtuse or deliberately baiting me. Knots are not the same as mph. Knots are 1.15 times MPH so 380knots would be 437mph. Congratulations!!! we now have a Firefly that can outrun a Mustang and do it while carrying a pair of 1000bs bombs under the wing.

MPH it should be MPH. Careless yes, obtuse, I cannot see how

No WW II aircraft was speced at range with maximum speed. The Speed may be specified and the range at a suitable cruising speed may be specified but claiming the the Firefly was "speced" to fly 1300 miles at 380kts is pure hocum. That or it is fueled by Fosters.

I never said that the firefly was speced to fly 1300 miles @ 380 (Kts). I did say that once at the target it had to be able to fly at that speed, or otherwise could not be said to meet specification (. If you stop and think about it, thats a different proposition to what you are attempting to brand me with at this point. In fact i was at pains to point out that enroute the aircraft had to fly at a cruising speed a lot less than 380 (kts). In other words the flight profile would be cruise/full throttle/cruise. This was how a lot of recon aircraft flew incidentally....dont believe me, have a look at spitfire PRU overflights.....or just about any other recon unit. The only difference for the Firefly is that they did their missions fully armed . Now, by extension, if you replace the weight of the fuel with the weight of bombs, then apart from the aerodynamic drag what additional effect can possibly explain this alleged loss of performance you keep harping about. Persoonally, I dont think ther is any basis for it, I suspect its just an opinion you have decided to settle on, and will not listen or discuss any other POV whatsover.

Welcome to the forum

oh, and for the record, I dont drink...not even a little.
 
This a report dated April 1943. The salient conclusions drawn from that report are that for the mosquito bIV it matter not whether the stores were being carried or not...performance was virtually the same. Guess some aircraft dont mind carrying a little weight.........

If that is accepted, then to try to return this debate to the issue at hand, if its possible to design and build a levle bomber with no impairment empty or loaded with the technology available, then why couldnt it be possible to design and build a Divebomber with a similar result. Moreover the BIV remained one of the fastest aircraft (particularly over long distances) for more than two years after its introduction, which is a long period of time for the war.

I would suggest that the main difficulty in designing a "fast" divebomber is its mission requirements. to be effective as a Divebomber it needed to have a relatively slow divesped, and controllable flight characteristics. However this was not an impossible task. Products like the patented youngman wing provided just such a solution. i am sure there were others .

So, ion my book the trick is to design an aircraft aerodynaically clean, reduced weight but with technology to allow controllable delivey of the ordinance. In 1940, this probably meant ditching the aft crewman and restricting the bombload. To reduce vulnerability, lelvel sp probably needed to be kept above 300 MPH.

The answer to that imaginary specification is beyond me, others will need to conside whether such a spec was technologically possible for 1940. Some of the technology did not exist, like the specialized wing forms, but they were close to development ...its a question of if it could be developed 1938 instead of 1940
 

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I don't argue with physics, just some peoples application of it. This explanation/definition works great for bullets, but is a bit suspect for aircraft. The basic Kinetic energy vs momentum thing is true but trying to turn it into aircraft performance leaves out a rather important factor, aerodynamic drag. If you could double the weight of a particular aircraft without changing it's drag the speed reduction would be ZERO in theory, you have increased the induced drag of the lift from the wing so reality is that the plane is a bit slower.
However, in General and in WW II reference time a 14,000lb airplane did not have the same drag as a 7,000lb airplane. The 14,000lb plane had a bigger wing, it had a longer fuselage and bigger tail. It had more profile drag and more surface drag. It had the induced drag also. Now I will freely admit that a 14,000lb plane (single engine ) doesn't have to have twice the drag of a 7,000lb (single engine) plane but given the same power/thrust
if the 14,000lb planes has 10% more drag it will about 20% slower. TWO 7,000lb planes, if one has 10% more drag it will be about 20% slower than the other one.

Gee, 1320 knots on the deck. And with an under wing load too......a secret 600mph in hand it could probably outrun an SR-71

I thought I had tried to refute your F-111 argument. Lets try for round II.

General Dynamics F-111

Notice the max speed 914mph at sea level, not 1320knots or 1320 mph.

Same figures in "the American Fighter" by Angelucci and Bowers.

Jane's 1975 says mach 1.2 at sea level which isn't far from the above but way off from 1320mph.


I gave you an opportunity to correct your statement on the 1320kts to Kilometers an hour, an understandable point of confusion, you didn't take it.


Now you are either being obtuse or deliberately baiting me.... Firefly that can outrun a Mustang and do it while carrying a pair of 1000bs bombs under the wing.
parsifal said:
MPH it should be MPH. Careless yes, obtuse, I cannot see how
Click to expand...

I pointed out what I believed to be an error the 380kt vs 386 mph thing by asking for a source. you came back with " I dont have figures to prove that the firefly could travel at 380 knots whilst at 1300 miles range, but one could reasonably expect it to, otherwise it was not meeting the design spec." which rather ignores the conflict in speed and begins a new argument.

Actually you have claimed a number of things for the Firefly that make it sound like super plane.From post #46.

1. " However, as a fighter /recon, it had a combat radius of about 1300 NM" (Range might be better than radius, especially combat radius which implies reserves for both combat and safety margin for return flight, we are back to the nautical miles or knots thing again, granted specifications were sometimes written using NM or kts but they are not interchangeable with statute miles or mph.)
2." As a strike aircraft it had a combat radius of about 500 NM when carrying its full payload" (now full payload isn't given which leads to speculation. Considering that a range of 1300 miles was possible by carrying two drop tanks of 90imp gal each?) and a range of about 880-900 miles possible without tanks (at 220mph) I certainly have to wonder what this strike payload was, the 20mm ammo in the wings? it certainly can't be any bombs or stores that would block the drop tank attachment points.)
3."Clearly the fighter/recon version was intended to carry fuel instead of bombs, and a lot of it. Fully loaded, as a fighter the mk IV was expected to have a speed in excess of 380 knots." ( we have gone over the knot thing. we need to define "fully loaded" drop tanks or no drop tanks is fully loaded?)
4."To be honest, i am not exactly sure what its peformance was when operating in a non-fighter capacity, but some of the old timers I talked to years ago simply said, when asked this very question by me, was essentially there was not much difference in the performance of the fighter version and the bomber version, in terms of speed at least." ( this may be true depending on the Version the old timers are talking about, The MK5,6 and 7 aircraft flew pretty much as standard in fighter configuration with a radar pod under one wing and a drop tank under the other. swapping those under wing loads for bombs could mean there was little difference in performance. With over 5 times as may of these later planes built as the MK IV which is it more likely the old timers flew?)

When I questioned the performance of the Firefly you came back with this from Post #49

"Its design spec was to operate at a certain speed at a certain range. I dont know it was using drop tanks or internal fuel to achieve that range, but the speed spec was a given. if the aircraft could not operate at that speed, at the range given, then the design was not meeting the spec. Getting to the target is a different matter, typically all aircraft, including fighters used to vector out to intercept an incoming strike will travel at a lot less than the design speed whilst in transit. I dont have figures to prove that the firefly could travel at 380 knots whilst at 1300 miles range, but one could reasonably expect it to, otherwise it was not meeting the design spec."
which is clear as mud when it comes to figuring out that you ment that the Firefly could touch 380 MPH for a few minutes during that 1300 mile journey considering that I never said it couldn't do 380mph clean, you seem to be claiming it could do 380mph with underwing stores?

 
The question isn't if adding weight to a plane will decrease it's speed but will it decrease it's performance in general, not only speed but climb, turning ability (sustained turn speed or ability to accelerate after speed has bled off due to a maneuverer) People have claimed that a smaller, single seat dive bomber could "take care of itself" either to or from the target. While it will be harder to intercept, if it is intercepted it is going to have a hard time taking care of itself if it retains the bomb load. If it jettisons the bomb load to "improve" it's ability to defend itself the defense has "scored" a "mission kill" even if no aircraft on either side are shot down. The bombers have failed in their mission to drop bombs on the target.
Helldiver or Hellcat with a pair of 1000lb bombs, either one is going to need escort fighters to increase the odds of getting bombs to the target.
 

This seems to be a somewhat different position to the one you were taking earlier, but then perhaps I misunderstood you. I thought your position was that an aircraft that was carrying bombs would suffer a performance penalty. This i can see is not quite the same as what I was saying. I have been saying that airspeed for a bomber is a good way to reduce its vulnerability. You have criticised that from the beginning as being not possible, or at least implying its not possible. Now we see, that is not what you meant. now its (apparently) that it cannot turn or accelarate or climb, as quickly.

So, just so we are clear, these are the questions I would like you to answer as simply as possible

1) Does airspeed decrease the vulnerability of a strike aircraft, and if so, does it significantly affect the issue?
2) Is it possible for an aircraft to have virtually no effect on its level speed when carrying a bombload?
3) Is it possible to design an aircraft for divebombing with a high speed
4) If the answer to (3) is yes, what would be the constraints affecting a 1940 design for this type of aircraft?

You seem to be saying that aircraft performance other than speed will be affected by bombload, still appearing to adhere to the view that bombers are always vulnerable if they are carrying bombs. Yet the experience of the Mosquito stands in sharp contrast to that position, as does the experience of the RAAF with the F-111 on excercise many years later..

To be fair, you at least paid lip service to the idea that high speed was some benefit (and then appeared to imply that achieving that speed advantage was not really possible). But then this apparently contradicts the report I posted on the Mosquito, which stands in stark contradiction to what you are saying. According to one source i have read, in the entire war, the Mosquito bomber lost just 209 aircraft to combat courses, of which just 118 could be attributed to direct enemy action. I will dig this report up later tonite and post it if I can locate it. Surely however, you will at least accept that the Mosquito enjoyed a low loss rate and no evidence of a high abort rate that i know of?

So, assuming you are right, that manouverability and climb performance was affected by the bombload, and that speed was not the only factor in determining vulnerbaility, and in fact was a relatively minor factor (please correct me if that is a wrong interpretation) in determining survivability, how does the Mosquito achieve such a low loss rate? Moreover the mosquito was seldom escorted and operated in daylight as much as it did at night. Most of the daylight raids undertaken by BC in the last half of the war were undertaken by unescorte Mossies, often operating at zero altitude. This assumes that they did achieve a low loss rate, and were fairly successful in completing missions.

Its amazes me how the more things change, the more they stay the same. People in 1941 argued that an unarmed bomber travelling at high speed was a waste....it was impossible for a bomber to outrun the enemy interceptors...the answer was ever increasing defensive armament, forget speed, it was firepower that protected a bomber. Tight formations moving slowly across enemy territory demolishing enemy defences as they went. This was one solution, but was it the best and was it the only solution......and postwar experience showed that it was the speed formula for bombers that was the dominant issue rather than defensive armament, that all but disappeared from strike aircraft after the war.
 
Here is my second post in this thread.

"In some cases the rear seater was also the radio operator and/or observer. If he is going to be there anyway you might as well give him a gun.
The 1940 dive bombers were rather low powered, A 1940 Dauntless had just 1000hp not 1200 or more, that came later. Once you have a plane that can lift a 1000lb bomb from the short runways or carrier decks and more fuel than some fighters you had a plane with over 300sq ft of wing, in some cases well over 300 sq ft., even if they dropped the bomb when bounced (a mission kill right there) they are too big and slow to out run or out maneuver real fighters for very long."

Let's look at the Dauntless dive bombers, the SBD-1 had a 1000hp for take off engine as did the next three models. The -1 had tanks for 210 US gallons, the -2 had 310 US gallons, the -3 had 260 gallons in tanks with self sealing liners, as did the -4. The -5 gets a 1200hp for take-off engine but empty weight is 6,404lbs or more than a Curtiss Hawk 75 using the same engine does fully loaded. The Dauntless had a 325sq ft wing compared to the Hawks 236 sq ft. It doesn't take a rocket scientist to figure out that the Dauntless wasn't going to last long against the Hawk or a plane that performed the same or better than the Hawk should they come in contact.
In the manuals section of this site there is a manual for the SBD-3 just the first dozen pages make interesting reading for this argument. While the SBD had tankage for large quantities of fuel it was only filled for certain missions. However the plane had to sized to accommodate the fuel tanks. It appears that running at similar weights the the carriage of the 1000lb bomb caused a loss of speed of 8-10 KTs (yes knots) depending on speed (full throttle or cruising) This is for a plane carrying the 1000lb bomb and 100 gals of fuel compared to a a plane without bomb and 310 gallons of fuel.

http://www.ww2aircraft.net/forum/ot...ad-pilots-handbook-sbd-3-dauntless-25828.html

I believe in a later post I said that the in practice the two seat dive bombers were not able to defend themselves all that well at least some of the time. That was to cover nit-pickers who could point to a few isolated engagements were the rear gunners did score. The US did a big swing, they went from the Dauntless to the Helldiver which wasn't that far from the Dauntless concept, just more of everything. The next series of dive or attack bombers used R-2800 or R-3350 engines and started to look like single engine B-25s with top and bottom twin .50 power turrets with remote sighting and lord knows what. Fortunately sanity prevailed and pendulum went the other way, If B-25s and B-26s couldn't defend themselves with multiple gun turrets there is no reason to believe these single engine monsters could either. If you were going to need escorts (or you had complete air supremacy) you might as well ditch the thousands of pounds of turrets and use the weight, space, and drag reduction for increase payload and range. With these piston engine designs the Americans while ditching defensive armament didn't really go to the "speed is defense" position, instead they were bomb trucks. While an early Skyraider could hit 348 at sea level that is clean, no bombs, and a contemporary fighter is the Sea Fury. NASA scientist not needed to predict that outcome either. Could a lightly loaded Skyraider (two pylons only?) have enough penetration speed to cause problems for an air defense system? Quite possibly, but it is a gamble.
I will grant you that these American aircraft (martin mauler, too) were not in the Spirit of the Mosquito.
Using the Mosquito as an example does have few problems however, 1, it couldn't really dive bomb like a Stuka or SBD or Val. Not only do you need dive brakes you may need a stronger airframe? I could be corrected, what was the Mosquito rated for in "G"s for pullouts or maneuvering? 2, At the time of it's introduction the Mosquito's potential was unrealized. It was sort of a superfast Blenheim with a 1000lb bomb load, soon improved to 2,000lbs but even that looks a bit skimpy compared to a Merlin powered Wellington let alone a Whitley. Some planes turn out better than even the designer expects. The Mosquito went on to do many great things and did prove it's concept.

Now for the questions that you request I answer in a simplistic manner.
1. increased airspeed will decrease the vulnerability of a strike aircraft by making interception more difficult in an area sense. This of course depends on the actual strike speed of the aircraft and the patrol speed of the interceptors. Neither one is using full throttle (military power) until visual sighting is made. The closer the match between the two aircraft the better for the strike aircraft. A 3 to 2 speed ratio in favor of the interceptor obviously is much better than a 6 to 5 ratio for the interceptor.
2. Yes, if the bomb load is carried internally. But that requires a bigger airplane to begin with.
3. Yes, I would say so.
4. Constraints would be field lengths and range desired with what size bomb load. Put those together with the low powered engines and you have problems.
 
Reading Ian Thirsk's "de Havilland Mosquito, An Illustrated History, Volume 2" the account relevantly states
"Mosquito bombers flew a total of 39,795 sorties during the Second World War, delivering 26,867 tons of bombs. Losses amounted to 254 aircraft, representing a loss rate of 0.63 percent, the lowest of any aircraft in Bomber Command

In 12859 daytime sorties there were 148 Mosquitos lost, at a rate of 1.15%. Not unsurprisingly, significantly greater than for night time operations. But still far below the loss rate of Lancasters (which flew mostly at night) and US B-17s."

According to "The de Havilland Mosquito as an Unarmed Bomber",

"No 105 soon discovered that the Mosquito B Mk IV was just faster than the Fw 190 at sea level, and just slower at altitude. The basic principle behind the Mosquito, of safety through speed, was proved to be valid – the German fighters would have to be very lucky to intercept an aircraft that could match (or almost match) their speed."

Clearly it was not necessary for the bomber to be outright faster than the SE interceptors pursuing it, merely being fast gave it some measure of immunity.

Its good to see you are prepared to concede that speed is an advantage in an area sense, but I would say that the advantage applies even in a tactical sense, as per the interception example I outlined earlier. Even this does not outline the issue sufficiently well. Forcing the interceptors to work harder to achieve a firing solution means they have to open their throttles to close to engagement range, which in turn reduces their engaement times. if they have to open their throttles to close the distance, the time they can spend in engagement is reduced, sometimes made impossible. This is the main reason why the Mossie could bomb targets with relative impunity....their pusuers simply did not have the endurance to keep up with them. Mosquitoes cruised at 280 MPH which is fast, even for a fighter. Several Mosquitoes were tested with hi octanes fuel and overboost achieved speeds of close to 445 MPH from memory. Travelling at its full speed, whatever that may be, made it harder to keep them in the cross hairs, which again reduced loss rates IMO.

In regard to your question about whether a Mossie could divebomb, well sought of.. they could dive the same as any other fighter could, from my reading, but like all other aircraft not designed for the purpose, their airspeed would build up and make their bomb runs at these angles (above about 40 degrees, I suppose) less conrtrollable and less accurate. Mosquitoes were notable for their ability to hit pinpoint targets, but its a stretch to say they could hit with D/B accuracy. The only way this could be achieved was to make them a divebomber, or give them wings that somehow reduced their divespeed to controllable levels. Which is why i originally mentioned the Firefly. It too was not a true divebomber, it was a fighter that just hapened to have wings that gave it a great deal of controllability in a dive. These were the so-called Youngman wings, which worked similarly to those fitted to the barracuda (ie with flaps) , but were recessed and retractable into the main wing structure. The firefly as an ASW aircraft was controllable enough to be an effective Sub-killer, yet "hot" enough to contain a good measure of survivability. What i am suggesting or perhaps asking is, why wouldnt it be possible to design a "hot" performer, like a mossie, but with a special wing, like the youngman wing, so as to make its divebombing ability slower in the dive (when the flaps are deployed) and more controllable and hence more accurate.

So in the first instance, was it possible to have a a "hot performer" in 1940, but with controllable dive characteristics. In one regard the lack of engine power appears to be a real issue, but also a lot of this technology was not in existence. Youngman wings were not developed until 1943, the Mosquito aerodynamics were not really finalized until 1941, and neither were the twin 1600 HP Merlins (I think 61s???) ready until then. Reducing the packages overall HP by 800 HP is going to have a big effect on its performance

One minor issue. mosquito BIVs were carrying 4000 lbs of bombs without significant impact on performance by May 1943, as indicated in the report I earlier posted. They often only carried 2000lbs, i suspect (but dont know) because of the manouverability and/or endurance considerations. Ive not heard the opinion before that a Mossie was a big aircraft. The one on display here in Aus war memorial is next to a mustang....though the Mossie is bigger, its not much bigger....so i was a bit curious about that
 
Reading Ian Thirsk's "de Havilland Mosquito, An Illustrated History, Volume 2" the account relevantly states
"Mosquito bombers flew a total of 39,795 sorties during the Second World War, delivering 26,867 tons of bombs. Losses amounted to 254 aircraft, representing a loss rate of 0.63 percent, the lowest of any aircraft in Bomber Command

In 12859 daytime sorties there were 148 Mosquitos lost, at a rate of 1.15%. Not unsurprisingly, significantly greater than for night time operations. But still far below the loss rate of Lancasters (which flew mostly at night) and US B-17s."

According to "The de Havilland Mosquito as an Unarmed Bomber",

"No 105 soon discovered that the Mosquito B Mk IV was just faster than the Fw 190 at sea level, and just slower at altitude. The basic principle behind the Mosquito, of safety through speed, was proved to be valid – the German fighters would have to be very lucky to intercept an aircraft that could match (or almost match) their speed."

Clearly it was not necessary for the bomber to be outright faster than the SE interceptors pursuing it, merely being fast gave it some measure of immunity.

Its good to see you are prepared to concede that speed is an advantage in an area sense, but I would say that the advantage applies even in a tactical sense, as per the interception example I outlined earlier. Even this does not outline the issue sufficiently well. Forcing the interceptors to work harder to achieve a firing solution means they have to open their throttles to close to engagement range, which in turn reduces their engaement times. if they have to open their throttles to close the distance, the time they can spend in engagement is reduced, sometimes made impossible. This is the main reason why the Mossie could bomb targets with relative impunity....their pusuers simply did not have the endurance to keep up with them. Mosquitoes cruised at 280 MPH which is fast, even for a fighter. Several Mosquitoes were tested with hi octanes fuel and overboost achieved speeds of close to 445 MPH from memory. Travelling at its full speed, whatever that may be, made it harder to keep them in the cross hairs, which again reduced loss rates IMO.

In regard to your question about whether a Mossie could divebomb, well sought of.. they could dive the same as any other fighter could, from my reading, but like all other aircraft not designed for the purpose, their airspeed would build up and make their bomb runs at these angles (above about 40 degrees, I suppose) less conrtrollable and less accurate. Mosquitoes were notable for their ability to hit pinpoint targets, but its a stretch to say they could hit with D/B accuracy. The only way this could be achieved was to make them a divebomber, or give them wings that somehow reduced their divespeed to controllable levels. Which is why i originally mentioned the Firefly. It too was not a true divebomber, it was a fighter that just hapened to have wings that gave it a great deal of controllability in a dive. These were the so-called Youngman wings, which worked similarly to those fitted to the barracuda (ie with flaps) , but were recessed and retractable into the main wing structure. The firefly as an ASW aircraft was controllable enough to be an effective Sub-killer, yet "hot" enough to contain a good measure of survivability. What i am suggesting or perhaps asking is, why wouldnt it be possible to design a "hot" performer, like a mossie, but with a special wing, like the youngman wing, so as to make its divebombing ability slower in the dive (when the flaps are deployed) and more controllable and hence more accurate.

So in the first instance, was it possible to have a a "hot performer" in 1940, but with controllable dive characteristics. In one regard the lack of engine power appears to be a real issue, but also a lot of this technology was not in existence. Youngman wings were not developed until 1943, the Mosquito aerodynamics were not really finalized until 1941, and neither were the twin 1600 HP Merlins (I think 61s???) ready until then. Reducing the packages overall HP by 800 HP is going to have a big effect on its performance

One minor issue. mosquito BIVs were carrying 4000 lbs of bombs without significant impact on performance by May 1943, as indicated in the report I earlier posted. They often only carried 2000lbs, i suspect (but dont know) because of the manouverability and/or endurance considerations. Ive not heard the opinion before that a Mossie was a big aircraft. The one on display here in Aus war memorial is next to a mustang....though the Mossie is bigger, its not much bigger....so i was a bit curious about that
 
The Mosquito had a rather tight bomb bay as I understand it. It apparently was originally designed for four 250lb bombs. Just Like the Blenheim. Two side by side in the front of the bay and two side by side in the rear of the. bay. The Mosquito was one of those few aircraft that turned out FASTER than predicted. With this extra performance in hand it was found that the regular 500lb bomb, which was too long to fit one behind the other in the Mosquito, could have it's tail fins shortened a number of inches and still retain acceptable accuracy. This allowed four to be carried for the 2000lb load. I don't believe it was possible to carry 8 250lb bombs though. Nit-Pic here,the "4000 lbs of bombs" is a not quite right, it is " 4000 lbs of bomb" the Mosquito could carry a single 4000lb 'cookie' but may have needed bulged bomb bay doors to do it. Many Mosquito may have been retro fitted to do it.
here is article (short and not really adequate) but it does have a picture of the 'cookie' in a bombbay with 500lbs bombs.
English Bombs of WWII

While the carriage of such a weight/weapon at speed/range the Mosquito could achieve is impressive the 4000lb 'cookie' had no tail fins and was an area weapon if dropped from altitude, it tumbled and had a rather erratic descent to ground.

http://pic20.picturetrail.com/VOL1379/5854175/12380563/293962306.jpg

I don't believe the carriage of alternative bomb loads of that weight were possible but I stand to be corrected. Like no four 1000lb bombs or even six 500lb bombs? edit>internally<edit

This is not a slam against the Mosquito, some other planes had very strange combinations of weapons listed in order to reach their "maximum bomb load" Early B-25s and B-26s are listed as carrying 5200lbs but this was two 1600lb armor piercing bombs and a torpedo carried under the plane blocking the bomb bay doors. I will leave it to your imagination to work out the torpedo drop and then the climb to an altitude where the bombs will gain enough speed to actually penetrate battleship deck armor
Without the torpedo the size of the bombbay and the shackles limited the planes to 4,000lbs or less.

As for a "larger airplane" try to imagine the Mustang with a belly fairing like a pregnant guppy to enclose a 1000lb bomb, perhaps a P-40 would be better? move center section fuel tanks to wing guns bays so you can recess or semi reccess the bomb into the center section and then extend fuselage lines from the radiator fairing back to behind the cockpit to enclose the bomb? American dive bombers used wacking big radial engines so providing a fatter fuselage to house a bomb bay wasn't quite the problem it would be on a V-12 powered aircraft.

ALL characteristics of the plane have to be balanced against each other, especially in the initial design stage. While an air force may live with certain limitations in an aircraft adapted from one role to another they were less forgiving of certain limits when developing a new plane, especially in peace time. The size of air fields grew enormously during the war, apparently Vultee dive bombers operated from 6,000ft strips in Burma in 1944. I am not sure England HAD a 6,000ft Runway in 1939?
To put things into perspective a bit better consider that a Blenheim MK I (hardly a dive bomber but bear with me) at 12,500 gross was supposed to carry a 1000lb bomb load 1125miles at 220mph and do it after taking off with a 296 yd (888ft) take-off run.
If we take the numbers from a P-40E
http://www.zenoswarbirdvideos.com/Images/P-40/P-40TOCLC.pdf

we see that at 8700lb (full internal fuel and 500lb bomb) the P-40 needs 1600ft of runway minimum, trading fuel and ammo (pair of guns?) for the bomb to get the weight down to 8100lbs still requires a runway 400ft longer than the Blenheim, getting down to 7500lbs (no guns/ammo-restricted fuel) still requires 150 feet (16%) more runway.
What was the RAF requirement for field length for a proposed dive bomber in 1938-39? would they accept 500yds? would they insist on 350yds? this makes a big difference to the size of the wing or the need for highlift devices for landing.
That Blenheim was supposed to have a landing speed (stalling speed?) of 50mph which sounds rather unbelievable but the porkier MK V at 16,000lbs was supposed to stall at 70mph indicated?
BTW, Blenheim were not supposed to drop bombs if the dive exceeded 55 degrees. They didn't want bombs hitting parts of the aircraft
and the Blenheim didn't have a propeller in the way of the bomb bay.
Could, in 1938-39 they design a more advanced aircraft than the 1934-35 Blenheim? Sure, they could, I am only bring it up to show that there were many other requirements besides speed and bomb load, some of which could severely affect the design of the aircraft, and some of which either disappeared or were significantly relaxed in just a few more years.
A great dive bomber/strike aircraft that can't get off the ground from most of your air bases isn't much good.
 
The Mosquito had a rather tight bomb bay as I understand it. It apparently was originally designed for four 250lb bombs. Just Like the Blenheim. Two side by side in the front of the bay and two side by side in the rear of the. bay. The Mosquito was one of those few aircraft that turned out FASTER than predicted. With this extra performance in hand it was found that the regular 500lb bomb, which was too long to fit one behind the other in the Mosquito, could have it's tail fins shortened a number of inches and still retain acceptable accuracy. This allowed four to be carried for the 2000lb load. I don't believe it was possible to carry 8 250lb bombs though. Nit-Pic here,the "4000 lbs of bombs" is a not quite right, it is " 4000 lbs of bomb" the Mosquito could carry a single 4000lb 'cookie' but may have needed bulged bomb bay doors to do it. Many Mosquito may have been retro fitted to do it.

This is meant to be a short, abridged description of the main armament configuration of some Mosquito types. truth is, however that there was a bewildering array of weapons and bomb fitouts, so this is not a complete description, just a bit of a summary


These comments you have made are very tue of the series I BIV variant, built in june 1941, of which just 10 were built. The airframes were in fact the last of the PRI version, so as designed, these aircraft were neve intended to carry any bombs. I believe they had a hard time fitting even 2 x 250lb bombs into these aircraft which were essentially lash up conversions. Series 2 followed this and immediately redesigned and enlarged the bomb bay to carry 4 x 500 standard bombs (By standard, I am not sure if this means your shortened version or the standard standard version). Fighter bomber versions like the FB VI I make no real comment on at this stage.

Its true that most of the series II BIVs (approximately 280 built) could not carry a 4000 lb HE bomb, however 54 were modified on the lines to carry 1000, 2000 or 4000 HE

the mk IX (again 54 built) could carry 250, 500, 2000 or 4000 lbs of bombs, either HE or incendiary. Ive neve heard of the BIX ever carrying 1000 pounders...dont know why. The BXVI used the same bomb bay assembly as the series II mk BIV, as modified for the Mk IX and pretty much the same airframe otherwise as the bIX. I am reasonably certain it could carry He or Incendiary up to 4000lbs, but will need to check

Of the FB variants, the first was the FB VI which was equipped with a somewhat derated powerplant, and was designed to carry just 2 x 250 lbs of bombs. later, the bomb bay was enlarged to carry 2 x 500lb modified 500 pounders, perhaps these are the bombs you are referring to? My sources dont mention 'modified 500 pounders for the bomber variants. I also dont know how many of the FB VI were built with the earlier bombay and how many with the late type. it may be, incidentally that carrying these bombloads, the FBVI was still effective as a fighter; in 1945 FB VIs in squadron strength destroyed 5 FW 190As and sank three ships in a maritime strike, whilst losing 5 of their own number. Kinda suggests that at that weight, the type was still competitive as a bomber....though i think it more likley that some of the squadron dropped their bombs to protect those that completed the mission.

Most FBs were able to divebomb, in the sense that a fighter carrying bombs could divebomb. Generally these attacks were limited to 30 degree attacks, though the type was rated to divebomb up to 55 degrees. i agree though, those big props must have been a bit of ahazard at such steep angles

As the war progressed the allies developed a preference for rocket firing FBs, and the Mosquito was no exception. These were of course underwing installations, and i dont know the performance penalty this installation caused. One would think quite substantial. A few were built with the 57mm Molins gun, a six pounder with an autoloader for ASW work mostly. Though it worked, it was found less satisfactory than rockets.....An interesting prototype that clearly shows the great strength of the airframe, a further development of the idea was carried out using the even larger 32-pounder, a gun based on the QF 3.7 inch AA gun designed for tank use, the airborne version using a novel form of muzzle brake. Developed to prove the feasibility of using such a large weapon in the Mosquito, this installation was not completed until after the war when it was flown and fired in a single aircraft without problems



I don't believe the carriage of alternative bomb loads of that weight were possible but I stand to be corrected. Like no four 1000lb bombs or even six 500lb bombs? edit>internally

As indicated above, partially right, but there are significant exceptions


This is not a slam against the Mosquito, some other planes had very strange combinations of weapons listed in order to reach their "maximum bomb load" Early B-25s and B-26s are listed as carrying 5200lbs but this was two 1600lb armor piercing bombs and a torpedo carried under the plane blocking the bomb bay doors. I will leave it to your imagination to work out the torpedo drop and then the climb to an altitude where the bombs will gain enough speed to actually penetrate battleship deck armor
Without the torpedo the size of the bombbay and the shackles limited the planes to 4,000lbs or less.


Interesting stuff about the Mitchells and Maruaders...I was unaware of that configuration. The thing to note about 'standard' armaments for the mossie, is that there really was no such thing ....with so many variants and roles, it carried a wide range of bombloads. i didnt view your post as any sort of misrepresentation of the Mosquito capability. It had limits thats for sure


As for a "larger airplane" try to imagine the Mustang with a belly fairing like a pregnant guppy to enclose a 1000lb bomb, perhaps a P-40 would be better? move center section fuel tanks to wing guns bays so you can recess or semi reccess the bomb into the center section and then extend fuselage lines from the radiator fairing back to behind the cockpit to enclose the bomb? American dive bombers used wacking big radial engines so providing a fatter fuselage to house a bomb bay wasn't quite the problem it would be on a V-12 powered aircraft.

I admit bias in favour of the Mossie, but my opinion is that the larger bombay was fitted into the design without major butchering of its great lines

I will have to some further research to replay to the second part of your post....
 
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