AHC: the best possible Luftwaffe for 1940

Deleted member 1487

One other thing that should be noted in general is that a gun's rate of fire will slow somewhat as the gun's mechanism is scaled up. The power of the recoil (or gas piston) increases due to a heavier shell, and this greater power should drive the mechanism at a higher speed, but it is more than canceled out by the other increases. The size and mass of both the cartridge and bolt increase, requiring more force to move them at a given speed, and since the cartridge is longer, it will have to move back and forward a greater distance to eject and reload the rounds. Both of these mean that gun rate of fire tends to decrease as a mechanism is scaled up, even though the Q factor usually remains the same at a given muzzle velocity (it is after all a measurement of the inherent mechanism of the gun, not its size). On the WWII aircraft gun chart, it can be seen that guns of a given family have decreasing rates of fire as the cartridge power increases. The most prolific gun family on the chart is the Browning, with the .30 M2 and .303 having 1150-1200 rpm, the Ho-103 having 800-900 rpm, the .50 M2 and Ho-5 having 750-850 rpm, the Ho-155 having 400 and then 500 rpm, and the Ho-204 having 300-400 rpm. These all used the same basic mechanism. The same can be seen with the Oerlikon family (including the MG FF and 20 mm Type 2), the Berlin UB and B-20, the ShKAS and ShVAK, the NS-37/45 and NS-23, etc.
The M2 used a more powerful cartridge than the Ho-103. The aircraft version of the M2 used lighter parts to speed up the ROF.
 
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Deleted member 1487

Curtiss XP-40 lost almost 50 mph from poor radiator shape and location, so it could be a lot worse
Given that the DB601 radiator was already a known quantity, the drag it imposed wasn't anywhere near that substantial.
 
The M2 used a more powerful cartridge than the Ho-103. The aircraft version of the M2 used lighter parts to speed up the ROF.
That would be the version of the M2 represented in the chart (the M2 Heavy Barrel has around 450-600 rpm), and the cartridge accounts for its lower rate of fire than the Ho-103.
 

Deleted member 1487

I'm glad tat you've gotten the book, and look forward to see some scans from it, hopefully the facsimiles of test reports.
Re. DB 601N - that will also give extra performance to the Bf 109Es and He 100s.
I will get some of that done today.

Several remarks for the speed figure, and expected performance loss for a service-worthy aircraft.
We have Fw 190A-5 in over-boost (1900-2000 HP) making less than 600 km/h under 2.7 km. Fw 190D-9 with MW 50 (= ~2000 HP) doing 600 km/h at 1 km. Bf 109K-4 does 580 km/h at SL on 1800 HP. Tempest V with 2100 HP, less than 400 mph at 1km. P-51B using 1830 HP (150 grade fuel) doing 368 mph at 1.3 km. These aircraft have advantage of lower weight and/or smaller size (especialy German fighters), some of them with very good/excellent cooling system. None has extra drag provided by engines in nacelles.
All said, the figure of almost 400 mph at low level for the Daimlerized Fw 187 requires a truckload of salt to digest, even if the said 187 is outfitted with evaporative cooling.
For a real-world example of a compact fighter (wing was even smaller than on the Jumo Fw 187s) powered by two DB 601As, in service outfit, we can take a look at IMAM Ro.58 - 378 mph clocked with 3 cannons and rear gunner.
The Fw190 used a more drag inducing engine with a wide frontal area and heavy engine, while the mass of the A5 was at least 4000kg without the MG FF (per German wikipedia), only some 1000kg less than the FW187. The D-9 was even heavier with longer wings, as it was designed as a higher altitude aircraft and had substantial drag at lower levels. The B109K4 was considerably heavier than earlier models and less than aerodynamically optimized by 1944 especially with it's heavy armament.
Also the Fw187V4 was without armament or armor, so was lighter than a combat production model would be, especially with a second crewman for the radio. Also they don't say what 'low level' means in terms of the test, which I guess could be up to 1.6km, as the lowest level speed I could find on some of the charts was 1.6km.
 

Deleted member 1487

Not just that it was fitted as engine-cannon on Bf 109F0s, it was also specified as wepon on He 100D. People at Dornier went one step ahead, offering even bigger Oerlikon FFS as engine-cannons(!) on Do 215.
Fitted or just proposed?
And engine cannon on the Do215? How would that even work?

I've proposed the 'MG 141' as a clean-sheet design. The weak-ish ~.50 in cartriges (Italian or MG 131) will not work well, or at all as base, probably the best bet is to neck-out the 13mm TuF of ww1 vintage for Germans. French 13.2mm or US .50 BMG might also work, those two were powerful.
Granted, the 'MG 141' will be too late for 1939/40, unless Germans axe both MG 131 and 151 early on and concentrate on the 141.
They'd have to convert the TuF into a rimless version, but it could work with modern powders. If it wouldn't be in significant use in 1940 it's not really worth considering here though.

The 500 kg bombs were long, at 2000+mm, vs. ~1650 mm for 250 kg.
I' can't find any lead towards a He 111 carrying anything in vertical rack other than 250 kg bombs. But never the less, and even with 250 kg bombs only, me likes the Ju-88 + vertical bomb storage.
I know the He111 didn't, but I'm more concerned about whether it could or couldn't due to size. The vertical bomb storage probably wouldn't work as well for use with the 50kg bombs, but the He111 did use the 250kg vertical racks to deploy 50kg bombs as well.
 
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The Fw190 used a more drag inducing engine with a wide frontal area and heavy engine, while the mass of the A5 was at least 4000kg without the MG FF (per German wikipedia), only some 1000kg less than the FW187. The D-9 was even heavier with longer wings, as it was designed as a higher altitude aircraft and had substantial drag at lower levels. The B109K4 was considerably heavier than earlier models and less than aerodynamically optimized by 1944 especially with it's heavy armament.
Also the Fw187V4 was without armament or armor, so was lighter than a combat production model would be, especially with a second crewman for the radio. Also they don't say what 'low level' means in terms of the test, which I guess could be up to 1.6km, as the lowest level speed I could find on some of the charts was 1.6km.

Bf 109K was aerodynamically optimized vs. Bf 109G6 and vs. 109E. Half the wing area vs. Fw 187.
Fw 190 still has just one engine. The 190D9 have had as small wings as 190A, it was not a high altitude aircraft, and it was faster than Fw 190As on any altitude on same HP.
Should we compare weight of Jumo Fw 187 when it suits us, and then switch to performance of DB Fw 187 when that suits us? What was actual weight for take off of the DB Fw 187?

Fitted or just proposed?
And engine cannon on the Do215? How would that even work?

On Bf 109F0 - fitted. On He 100 - accounted for in data sheet, plus opening in spinner on last He 100s produced.
Manual for the Do 215, with FFS cannons depicted (pg. 66) and accounted for (pg. 60, 61 and 63); 100 rd drum : link

They'd have to convert the TuF into a rimless version, but it could work with modern powders. If it wouldn't be in significant use in 1940 it's not really worth considering here though.

Rim can stay, rimmed and/or semi-rimmed cartridges worked just fine in Soviet (both 7.62 and 20mm), Brtish, Japanese and Italian automatic weapons. Both rimmed and non-rimmed cartridges also worked with either modern and non-modern powders. Rimmed != rimfire.
 

Deleted member 1487

Here are some scans from the Fw187 book. I have others, but these are pretty large and show what the capabilities of their aircraft were. Some of the others are comparing the Fw187 with the Westland Whirlwind, Mosquito FB, and P-38.

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Here are some scans from the Fw187 book. I have others, but these are pretty large and show what the capabilities of their aircraft were. Some of the others are comparing the Fw187 with the Westland Whirlwind, Mosquito FB, and P-38.

Thank you for the scans.

Some questions/issues, though. Was the Fw 187 ever outfitted with DB 605 engines? Type of cooling for such a version? Is there a facsimile of a real test report in the book, vs. calculated graphs? The Fw 187 with DB 605 + 1000kg bomb = 8250 kg, yet without bomb it is 6050 kg for same A/C that is to out-climb the Fw 190s? DB 605 on C3 fuel for Fw 187 climb graph? Rated altitude of DB 605 on full ram is really 8000m?
 

Deleted member 1487

Thank you for the scans.

Some questions/issues, though. Was the Fw 187 ever outfitted with DB 605 engines? Type of cooling for such a version? Is there a facsimile of a real test report in the book, vs. calculated graphs? The Fw 187 with DB 605 + 1000kg bomb = 8250 kg, yet without bomb it is 6050 kg for same A/C that is to out-climb the Fw 190s? DB 605 on C3 fuel for Fw 187 climb graph? Rated altitude of DB 605 on full ram is really 8000m?
Yes, but they were not actually test flown because of a scrap order by the RLM right before they were ready. From what I understand the numbers are calculated, not sure based exactly on what, but there was extensive testing of the Jumo 210G prototype and A-0 series, so those numbers are real and I'd imagine the basis of some of the calculations. One of the A-0s of the industrial protection unit was credited with a Spitfire kill in 1943 as an aside. The rated altitude of the DB605 is for the AS series which used the DB603 supercharger to get better altitude performance.
 
Yes, but they were not actually test flown because of a scrap order by the RLM right before they were ready. From what I understand the numbers are calculated, not sure based exactly on what, but there was extensive testing of the Jumo 210G prototype and A-0 series, so those numbers are real and I'd imagine the basis of some of the calculations. One of the A-0s of the industrial protection unit was credited with a Spitfire kill in 1943 as an aside. The rated altitude of the DB605 is for the AS series which used the DB603 supercharger to get better altitude performance.

I've asked many questions, what ones are best answered with 'yes'?

BTW - weapon manual for Bf 109F1(!) that has MG FFM as motor-cannon: link
 

Deleted member 1487

I've asked many questions, what ones are best answered with 'yes'?
I've answered the questions. The calculations and test date of the A-0 series are the best we have and given the comparisons with other aircraft that were using the same engine at the time and later modified to use the Daimler engines the Fw187 with a DB601 would have maintained the performance edge even if we can't say for 100% certainty that calculated numbers are what the real performance would be.

BTW - weapon manual for Bf 109F1(!) that has MG FFM as motor-cannon: link
K. Apparently they either modified the MG FFM was modified to fit in the space or the engine was modified somehow. Either way a smaller weapon could still fit in that space in the E-series.
 
I've answered the questions. The calculations and test date of the A-0 series are the best we have and given the comparisons with other aircraft that were using the same engine at the time and later modified to use the Daimler engines the Fw187 with a DB601 would have maintained the performance edge even if we can't say for 100% certainty that calculated numbers are what the real performance would be.

Okay.

K. Apparently they either modified the MG FFM was modified to fit in the space or the engine was modified somehow. Either way a smaller weapon could still fit in that space in the E-series.

Or they used the 'motorlafette' MoL-FF/1, that weighted 21.5 kg (including the blast tube) in order to install the MG FFM as-is on the Bf 109Fs as-is.
 

Deleted member 1487

Or they used the 'motorlafette' MoL-FF/1, that weighted 21.5 kg (including the blast tube) in order to install the MG FFM as-is on the Bf 109Fs as-is.
Ok, so they modified the cannon to mount it there rather than the motor cannon option being unavailable to something without the constraints of the MG FF.
 
Ok, so they modified the cannon to mount it there rather than the motor cannon option being unavailable to something without the constraints of the MG FF.
'Motorlafette' is a mounting, an interface between wepon, engine and fuseage. Not a modification of a weapon.
The MK 108 used MoL 108/1A and 108/1C, MK 103M used MoL 103/2A and MoL 103/3A.
 

Deleted member 1487

'Motorlafette' is a mounting, an interface between wepon, engine and fuseage. Not a modification of a weapon.
The MK 108 used MoL 108/1A and 108/1C, MK 103M used MoL 103/2A and MoL 103/3A.
Based on what I could find of the specifics for the MG FF, it required the MG FF version with a modified recoil mechanism from the lower energy round, which allowed it to mesh with the special mounting they made for it. Prior it was not able to mesh with motor mount due to a variety of factors. Apparently even with the MoL it still jammed during maneuvers and due to cold at altitude.
 
Based on what I could find of the specifics for the MG FF, it required the MG FF version with a modified recoil mechanism from the lower energy round, which allowed it to mesh with the special mounting they made for it. Prior it was not able to mesh with motor mount due to a variety of factors. Apparently even with the MoL it still jammed during maneuvers and due to cold at altitude.

The MG FFM differed vs. MG FF in recoil (weaker vs. stronger), that required change of return spring so the cannon can still function. Thus the FFM will be wrecked if FF ammo was used, while FF will not work with FFM ammo past 1st round.
At any rate, it seems like the FF didn't 'mixed' well with DB 601A, while FFM + DB 601N 'mixed' much better.
 

Deleted member 1487

@tomo pauk What's the ruling on suggesting that FFARs could be available by 1940? It would certainly help with shooting up airfields, convoys, trains, etc. by fighters. The technology isn't anything revolutionary either, just someone needs the idea.
 
@tomo pauk What's the ruling on suggesting that FFARs could be available by 1940? It would certainly help with shooting up airfields, convoys, trains, etc. by fighters. The technology isn't anything revolutionary either, just someone needs the idea.

IMO, rockets are a very good idea for 1940. Can also do supression of AA, attack on small ships, while fighters can defend themselves well once rockets are spent.
 
@tomo pauk What's the ruling on suggesting that FFARs could be available by 1940? It would certainly help with shooting up airfields, convoys, trains, etc. by fighters. The technology isn't anything revolutionary either, just someone needs the idea.
That depends on the type of rocket wanted. For somewhat lesser rockets like the Mousetrap family (Mousetrap, 4.5 inch Beach Barrage Rocket, and 7.2 inch Demolition Rocket), the M8 family (M8, T22, and M16), the RS-82 family (RS-82, RS-132, Katyusha rockets), the Unrotated Projectile family (UP, Z battery, RP-3, and Land Mattress), the Nebelwerfer family, and smaller handheld rocket launchers, the technology already existed. These interwar rockets were developed by many countries, but mainly by various scientists in Germany, by Georgy Langemak in the USSR (RS-82 family), by Alwyn Crow (Unrotated Projectile), and by Leslie Skinner in the US (Bazooka, M8 family).

For more powerful FFAR family (3.5 inch FFAR, 5 inch FFAR, and 5 inch HVAR), JATO, and Tiny Tim rockets the technology was not developed until June 1942.
The Group's aim was to find a replacement for black-powder rocket motors—units consisting of charcoal, sulfur and potassium nitrate with a binding agent. The mixture was unstable and there were frequent explosions damaging military aircraft. The solid JATO fuel invented by Parsons consisted of amide, corn starch, and ammonium nitratebound together in the JATO unit with glue and blotting paper. It was codenamed GALCIT-27, implying the previous invention of 26 new fuels. The first JATO tests using an ERCO Ercoupe plane took place in late July 1941; though they aided propulsion, the units frequently exploded and damaged the aircraft. Parsons theorized that this was because the ammonium nitrate became dangerously combustible following overnight storage, during which temperature and consistency changes had resulted in a chemical imbalance. Parsons and Malina accordingly devised a method in which they would fill the JATOs with the fuel in the early mornings shortly before the tests, enduring sleep deprivation to do so. On August 21, 1941, Navy Captain Homer J. Boushey, Jr.—watched by Clark Millikan and William F. Durand—piloted the JATO-equipped Ercoupe at March Air Force Base in Moreno Valley, California. It proved a success and reduced takeoff distance by 30%, but one of the JATOs partially exploded. Over the following weeks 62 further tests took place, and the NAS increased their grant to $125,000. During a series of static experiments, an exploding JATO did significant damage to the rear fuselage of an Ercoupe; one observer optimistically noted that "at least it wasn't a big hole", but necessary repairs delayed their efforts.
Despite these successes, Parsons, the project engineer of Aerojet's Solid Fuel Department, remained motivated to address the malfunctions observed during the Ercoupe tests. In June 1942, assisted by Mills and Miller, he focused his attention on developing an effective method of restricted burning when using solid rocket fuel, as the military demanded JATOs that could provide over 100 pounds of thrust without any risk of exploding. Although solid fuels such as GALCIT-27 were more storable than their liquid counterparts, they were disfavored for military JATO use as they provided less immediate thrust and did not have the versatility of being turned on and off mid-flight. Parsons tried to resolve GALCIT-27's stability issue with GALCIT-46, which replaced the former's ammonium nitrate with guanidine nitrate. To avoid the problems seen with ammonium nitrate, he had GALCIT-46 cooled and then heated prior to testing. When it failed the test, he realized that the fuel's binding black powders rather than the oxidizers had resulted in their instability, and in June that year had the idea of using liquid asphalt as an appropriate binding agent with potassium perchlorate as oxidizer.

Malina recounted that Parsons was inspired to use asphalt by the ancient incendiary weapon Greek fire; in a 1982 talk for the International Association of Astronomical Artists Captain Boushey stated that Parsons experienced an epiphany after watching workers using molten asphalt to fix tiles onto a roof. Known as GALCIT-53, this fuel proved to be significantly more stable than the Group's earlier concoctions, fulfilling Parsons' aim of creating a restricted-burn rocket fuel inside a castable container, and providing a thrust 427% more powerful than that of GALCIT-27. This set a precedent which according to his biographer John Carter "changed the future of rocket technology": the thermoplasticasphalt casting was durable in all climates, allowing for mass production and indefinite storage and transforming solid-fuel agents into a safe and viable form of rocket propulsion. Plasticized variants of Parsons' solid-fuel design invented by JPL's Charles Bartley were later used by NASA in Space Shuttle Solid Rocket Boosters and by the Strategic Air Command in Polaris, Poseidon and Minuteman intercontinental ballistic missiles.
https://en.wikipedia.org/wiki/Jack_...ncing_JATO_and_foundation_of_Aerojet:_1939–42

Because the FFAR family and Tiny Tim rockets were developed at Caltech after the June 1942 date of that invention, and because Caltech was essentially the home of the GALCIT Rocket Research Group, Aerojet, and JPL, I assume that these rockets required that technology to be created. The FFAR family, and possibly Tiny Tim, also is known to have used X-shaped propellant extrusions rather than the usual clusters of tubular pellets in other rockets.

As a postscript, there were 3 more major milestones in solid rocket booster development after that. The first was Charles Bartley's plasticized solid fuel. The second was the development of the Talos Missile booster (10 times larger than boosters then existing) and casting technology for them. The third was Edward N Hall's development of solid rocket motors again much larger than those then existing, used in Minuteman and Polaris ICBMs (the first solid fuel ICBMs). Finally, there is a document about Aerojet's involvement in solid rocket motor development, detailing certain technological milestones (in the last figure) since their founding.
 
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