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Subject: Aircraft Weapons and launch platforms, P-51 Mustang and P-38 Lightning.
heraldabc    12/22/2010 4:13:04 PM
Hypothesis: within the detection range of an engagement envelope there are two operation and decision cycles that are separate local events and that are mutually dependent upon each other. One local event is the launch platform which is the carriage and deploy mechanism. The other local event is the weapon as it operates across the interval from the launch platform to the target. The nature of the launch platform and the nature of the weapon act upon each other as an effectiveness ratio in doing work on the target. For this hypothesis we will use two concrete examples, the P-51 Mustang and the P-38 Lightning and discuss the shortcomings each platform had to the ideal solution that each tried to solve from its common military user perspective. Preliminary comments and questions welcome. H.
 
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YelliChink       12/23/2010 3:04:45 PM


Dare I say it? Kelly Johnson got it wrong. Yes I dared say it. 
Next up, how did we screw up the Mustang?

H.

Kelly Johnson didn't get it wrong. He got everything right. The problem is not Kelly Johnson, but rather USAAC officers and generals who conjectured up twin-engine fighter concept and gave fundings for V1710 with turbosupercharger. Mr Johnson is an aircraft design genius, and what he did is designed a package perfected for the customer's specification. Just because USAAC's dickheads (or in Chinese we call them swine heads) made the spec wrong, it doesn't traspire to Kelly Johnson.
 
As a result, if you absolutely, positively have to fight in a twin-engine fighter, you would rather be in a P-38 than any other contemporary twin-engine fighters. Not Bf-110, not Ju-88 and certainly not Pe-2.
 
Look at the history of weapons development in WW2, the generals usually got it wrong most of the time. Mustang is the result of private endeaver by North America to make something for the custormers. They subjected to zero bureaucratic decision from USAAC and Brits at that time just want to get as many airframe as possible to make up the mistake that the US is making today. Even the endeaver to mate Merlin 61 and Mustang airframe were from Merlin company and an RAF commander, not through top-down decision making procedure by USAAC.
 
The first Merlin P-51 (B/C models) are perfect for the role of high altitude bomber escorts. You screwed the Mustang when USAAF generals and colonels started to inject their own opinions.
 
Oh yeah we want bubble canopy, so modify the rear fusalage, and put more oil tanks in it.
Oooh we want more fire power, just add two more .50 cals into the wing, and change the structure if needed.
And don't forget to add the bomb rake and electrical connection and switches.
 
That's how you screw up a perfect good escort fighter. Fortunately, the enemy screwed even more.
 
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YelliChink       12/23/2010 3:41:27 PM

There was never a large enough margin between the DB and RR engines to make that "no doubt" statement, espcially at higher altitudes. The greatest advantages of the DB 601-605 relate to the layout of the units themselves, allowing for a central gun and a more aerodynamic nose section, they did this despite having a larger capacity engine. In terms of complexity and reliability there's also evidence that is favourable to the Merlins.The bottom line is that the parallel evolution that both designs underwent throughout the war was roughly equivalent in performance terms. 


Ze Germans were using fuel injection from the beginning, while the Brits were still using carburetor until much later. I forgot whether the monstrous Griffon and Navier Sabre engines use carburetors or fuel injection. As a result, early Merlin engines will choke while subjecting to negative G. Many early German pilots escaped by pulling negative G knowing RAF pilots couldn't follow. That problem was solved later, but the solution of swing carburetor is never as good as fuel injection.
 
Also the inverted V is superior than V IMHO. We are talking about aviation engines here so the loss of engine oil is inevitable. inveted V allows engine oil to flow downward toward the valves and camshafts, while it flows toward crankshaft in V engine. As a result, the DB series engines also allow installation of large caliber cannon through the shaft. The only downside I can think of is that they can't "cook the engine" the way Russians did during harsh winter, but eventually they found the other ways to do it.
 
Also, while Merlins have manual supercharger mode for emergency power, ze Germans developed MW50 for DB 605 and Jumo 213, clearly a superior design. Of course R2800 has similar stuff, but that's purely American adoptation on radial engine. However, none of the Allied fighters ever receive anything similar to GM-1.  When finally there was water-injection Merlins, it was too late. The war was almost over in Europe.
 
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heraldabc       12/23/2010 3:58:47 PM
Reply to various
 
Reactive       12/23/2010 11:46:34 AM

A really interesting thread - What was interesting about the Merlin was its versatility - it powered the majority of designs the British put in the air throughout the war, in terms of numbers produced the vast majority went into heavy bombers likely over 100 000 of 150 000 units in total manufactured. Wellington, Halifax, Lancaster, Beau-fighter, Mosquito, Hurricane, Spitfire, Mustang... not to mention 15 + less well known aircraft it also powered.. It was instrumental to the war effort in Europe, surely one of the best examples of the advantages of commonality and modularity in fighter design. 

Most of the Beaufighters used Hercules radial engines. AFAIK, the Merlin was too valuable for other aircraft when the Bristol radials were quite capable and what the aircraft was actually originally designed to use. The Beaufighters received derated Merlins when the Hercules was needed for Short Stirlings. Notice that the British were quite willing to make major production switches and design changes in a type on a temporary basis based on transient war conditions when they thought their war effort needed to do so?

 
YC 
 
The problem of Allison V1710 is that the USAAF made some very bad choices in the beginning. Instead of developing two-stage supercharger, they went with unknown turbosupercharger. Worse is that they cancelled turbosupercharger on P-39, ordered P-40 with only one stage supercharger. So between 1941 to 1943 when P-51B started to emerge in quantity, the only good long range fighter in the USAAF inventory is P-38. V1710 has some potential, but it was never fully developed. The later version used in F-82 isn't that bad, even though it is still inferior to comtemporary Merlin due to lack of intercooler and aftercooler. By that time the focus has been shifted to turbojet engine development.

1. The theory was sound in 1933. A turbo-charger does not need to be clutched to specific altitude bands and it does lend itself to taking power off the back-end  of the ICE work equation as exhaust driven instead of off the front end as mechanical takeoff. How was anyone to know about the Meridith Effect before that nimrod described it?    
2. The Airacobra  was a tight but asymmetrically cluttered  aero-shell design. The turbocharger scoop was in an awkward place and was a significant drag event in thick air. Was it the wrong  decision to allow the NACA weenies to tamper with the aeroshell in the name of cleaning up the airflow? Sure was, but you can just as easily damn Weight Patterson for penny-pinching on the turbo-charger which they did not feel was necessary for a mid-altitude band fighter  The idiots also chose the wrong armament package. It was another case of trying to turn a point defense  interceptor into a battlefield support aircraft.  Sound familiar?
 
The development goals of P-51 and P-38 were totally different. P-38 were developed as bomber interceptors. The designator "P" is for Pursue. The air warfare doctrine at the beginning of WW2 is very different from that of the end of the war. Fast bombers were considered capable of penetrating without fighter escort. Not only Americans thought so, Germans thought that as well. Not until in the mid of the war when everybody's bomber forces were trampled by fighter/intercepters, escorts were employed in large numbers. USAAF tried P-47 and P-38 as bomber escorts, but eventually the emerge of P-51 supplement the roles of the formers as bomber escorts.
 
3. The P-51 was originally designed to be what the Spitfire  was and what the P-40 falsely claimed to be- a target defense interceptor.   
4. As such, the weapon package as well as the original Allison engine were thew wrong choices. 
 
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YelliChink       12/23/2010 4:56:24 PM

6. German aerodynamics is claimed as superior by many people who don't know what they discuss. It depended on the designer. Kurt Tank and the Horten brothers were geniuses.  Papa Heinkel's, and Madman Dormier's design teams were competent.  Pretty Boy Willy Messerschmidt should have been shot for the garbage he designed. Junkers as a company was in a class by itself both for engines and for aircraft it designed. Those maniacs fit mission, engine, airframes and cargo (in the case of war-birds the weapons), bettwer than almost anyone in WW II. Very little waste either in the Ju-52,, Ju-87, or Ju-88. 


 

7. German liquid cooled engines were elegant masterpieces, their radials were competent, but their superchargers were crap. I would not say that their engines were the best, though. It depends on what you wanted the engine to do. German  engines certainly could not match Allied engines for ease of maintenance (exception  Merlin) or usable hours before teardown and rebuild. And for the design purpose for aircraft intended and elegance of  design I would stack the Honare up against any German radial  or even a Daimler Benze DB-6XX series.



H.


German superchargers were crap? You are the first and the only one I've heard from saying so. Inferior to Merlin/Griffon/Navier's supercharger, maybe, but certain still function better than the two-stage ones installed on V1710. You can't really compare the rather trouble-less American air-cooled radial engines such as R2800 to German liquid-cooled incline engines. Sure the German BMW 801 is no match to R2800. Inline vs inline, German superchargers were still the best in terms of engine performance. Had they not been distrupted by late war shortage and lack of quality, they would have done a better job in making them.
 
On aerodynamics. During the war, only the US has full access to the database of NACA airfoil wind tunnel tests. That is a huge advantage. Both Messerschmidt and Fokker-Wulf can make energy fighters, or they can make angle fighters, but they just can't make a fighter fly fast, climb rapidly, while turning tight. They are very competent in putting together an airframe to fit specific mission. However, without the NACA database, they simply can't do certain things. In real war, adaptability is more important than mission specific. Air combat in WW2 European theater raged from 40,000ft all the way down to the tree top level. Americans have managed to gain advantage in speed, maneuverability, dive and climb at all levels with P-51 and later versions of Spitfire and P-47.
 
Well, that except Ta-152H.
 
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earlm    German stuff is overrated   12/23/2010 5:07:07 PM
Note that they built high and low altitude versions of the Ta-152 since they couldn't make one plane work at a variety of levels.  Also check the difference in displacement between their engines and the opposition, larger to do the same job just like their tanks and battleships.
 
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Reactive       12/23/2010 6:01:52 PM
I know this is O/T but i'd be interested to hear Herald's/Yelli's view on whether the germans should have developed a heavy bomber? Having done so would it have fundamentally altered the dynamics (range and payload) of the Battle of Britain, or more importantly the Eastern Front.
 

 
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doggtag    Yeah, these are the good debates,...we don't do this often enough...   12/23/2010 6:18:09 PM
Nice, guys!  http://www.strategypage.com/CuteSoft_Client/CuteEditor/Images/emthup.gif" alt="" />http://www.strategypage.com/CuteSoft_Client/CuteEditor/Images/emthup.gif" alt="" />
 
Couple questions though:
 
Yelli:  Fokker-Wulf? AIUI, Fokker and Focke-Wulf  were two distinctly separate entities, were they not?
 
Herald:  High marks for the Ju-52, Ju-87, and Ju-88? Really?
 
The Ju-52, a tri-motor. Managed to need three engines to achieve what other nations were able to do with two engines for a light/medium transport. And it was some time before they even got away from the two-blade props on them, which didn't really transfer the most amount of useful energy out the engines, did they?
Then figure in how many of them had that corrugated sheet metal construction...yeah, I understand perfectly how the corrugated sheet metal added strength for the weight, but also you end up, externally, with more drag-inducing surface area, don't you?
Add in the ungainly, more often than not never-spatted landing gear, and that airframe looks like a horrible example for a transport aircraft: high drag wastes engine power, power which should be applied for more speed (isn't that the general argument when we discuss fighters?), more cargo, and/or more range.
More power gets heavier loads off the ground quicker, gets them there quicker, and more often than not, a quicker plane is more survivable (especially in the face of surface fire (AAA).
 
The Ju-87: a dive bomber (CAS?). Two forward firing 7.92mm MGs, one aft. No real armor protection for the crew.
Like combat aircraft of today, blitzkreig (shock and awe) against adversaries who lack any credible defensive aircraft and AAA, just about anything can work (we have UAVs the size and speed of small Cessnas that perform ideally under those situations).
But throw in a situation when the Allies (West or Eastern fronts) can throw fighter support into the air, and can have some measure of even limited organized AAA,
and then those Stukas suffered if they didn't have Luftwaffe fighter support.
And the only time the Stuka had any credible gun armament, the 3.7cm underslung gun pods with, what, like 15 rounds per gun?, its lack of any real armor made it no Sturmovic, an armored ground support aircraft whose guns weren't stuck on as an afterthought.
 
Were Stukas successful? Sure, so long as the Luftwaffe fighters controlled the local airspace,
and where there were few, if any, sizeable AAA.
 
The Ju-88: OK, perhaps some might merits in the design, but is having most of your crew (pilot, bombardier, gunners, etc) tightly grouped together in a "pod" really a good idea?
That just made it easier for multi-gunned Allied fighters to take out a lot of the crew just by hitting a smaller area of the target.
A similar flaw also seen in the medium Dorniers as well.
Add to that, thoughout their lives, most had mainly only multiple single 7.92mm MGs, even if later some of them managed to get 13mm MG131s and similar: hard to mount the larger MGs when your crew compartment is so cramped...
I saw one of those shows demostrating how the Ju-88 had all those little ammo mags stuffed everywhere around the crew compartment, and how is was often quite troublesome in the heat of battle for crewmen to be passing those ammo cassettes back and forth from all their storage areas.
As much as you dislike turrets, the Allies were far more success in designing a proper turret: generally, they kept their ammo mostly at the ready in large boxes linked right to the guns.
 
Perhaps the Germans looked at aircraft overall as examples designed for rapid manufacture: the Allies, especially US, had the luxury of desiging complex aircraft, generally much more survivable, in manufacturing plants that, as the War progressed, weren't under threat of constant bombardment or severe lack of resources and materiel...
 
No, I definitely don't consider those three aircraft as pinnacles of aviation success stories.
 
 
$.02.
 
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heraldabc       12/23/2010 6:52:25 PM

YelliChink       12/23/2010 3:04:45 PM




Dare I say it? Kelly Johnson got it wrong. Yes I dared say it. 

Next up, how did we screw up the Mustang?

H.


Kelly Johnson didn't get it wrong. He got everything right. The problem is not Kelly Johnson, but rather USAAC officers and generals who conjectured up twin-engine fighter concept and gave fundings for V1710 with turbo-supercharger. Mr Johnson is an aircraft design genius, and what he did is designed a package perfected for the customer's specification. Just because USAAC's dickheads (or in Chinese we call them swine heads) made the spec wrong, it doesn't traspire to Kelly Johnson.

That is the point isn't it? Refer to the P-51 example.  See what you write below that I highlight in red.

As a result, if you absolutely, positively have to fight in a twin-engine fighter, you would rather be in a P-38 than any other contemporary twin-engine fighters. Not Bf-110, not Ju-88 and certainly not Pe-2.

I would rather be in an F7F.

Look at the history of weapons development in WW2, the generals usually got it wrong most of the time. Mustang is the result of private endeavor by North America to make something for the customers. They subjected to zero bureaucratic decision from USAAC and Brits at that time just want to get as many airframe as possible to make up the mistake that the US is making (with the P-38, P-39 and P-40)  today. Even the endeavor to mate Merlin 61 and Mustang airframe were from Merlin company and an RAF commander, not through top-down decision making procedure by USAAC.

The first Merlin P-51 (B/C models) are perfect INTENDED for the role of high altitude bomber interceptor  escorts (Accident of design it became an escort) . You screwed the Mustang when USAAF generals and colonels started to inject their own opinions.

Oh yeah we want bubble canopy (correct decision), so modify the rear fuselage (botched-should have modified more area into the vertical stabilizer) , and put more oil tanks in it (needed).

Oooh we want more fire power, just add two more .50 cals into the wing, and change the structure if needed. (Botched decision. Four H0-5 type Brownings was the correct fix. It would fit the existing volume and mass margins.). And don't forget to add the bomb rake and electrical connection and switches. (overload the electrical supply and use the fighter for a role where other better designed ground attack planes [Jugs] were available.)

That's how you screw up a perfect good escort fighter. Fortunately, the enemy screwed even more.

 

 
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heraldabc       12/23/2010 7:01:21 PM
Herald:  High marks for the Ju-52, Ju-87, and Ju-88? Really?
 
For a dusted off (1930) shelved transport design, a second stab at a dive bomber (1938) and a second attempt at a medium bomber that went on to to morph into almost anything(1938) the Luftwaffe needed, after a hideously botched first Junkers attempt during a period when German radials were overweight and underpowered and when German aircraft designers were technically behind even the confused Russians?
 
Yes.
   
 
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heraldabc       12/23/2010 7:13:01 PM

I know this is O/T but i'd be interested to hear Herald's/Yelli's view on whether the germans should have developed a heavy bomber? Having done so would it have fundamentally altered the dynamics (range and payload) of the Battle of Britain, or more importantly the Eastern Front.


No. Work on an extended range Ju-88, and work out the bugs of  the Do-217 FASTER to replace the Do17 and fix the BMW 801 engine by early 1940, and for pity's sake retire the Heinkel 111 once you get those three critical boloed  items fixed!   
 
 
 
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