AHC: Wank the German aero-industry/Luftwaffe. 1920's POD

Deleted member 1487

It would've taken a hefty dose of handwavium to cancel out problems with flexing of a 2.5 m long crankshaft.
I'd certainly try to avoid the 606 and 604.
The V-16 Db601 sized shaft would have been smaller than the V-12 DB603 based shaft. Even with a 33% length increase over the DB601 it would have still been no longer than DB603

Making 1-20 aero engines per month during the 1st 6 months (when other types are churned in hundreds) is not 'Large-scale production', regardless of what the Mercedes-Benz PR department says.
Fact is it was in production and they were preparing it for service. As it was it was a DB601E with bored out cylinders and a variety of improvements to handle the increased power.
 
Perhaps the appearance of the Hawker Hart and Fury leads to one of the German Aero Engine firms obtaining a license for the Kestrel series of engines in 1929 or 30 allowing the Luftwaffe to skip its biplane fighters altogether when it comes into the open. Better fighters earlier would tend to suggest better defended bombers would need to be developed pre war.

How about the RR Buzzard? It was making some 50% more power than Kestrel in the late 1920s, meaning a bigger 'stretch' for future versions.

Fund Heinkel, Junkers, Muller, von Ohain, etc. development of gas turbines better during the 1930s. Earlier introduction of gas turbines provide 5 benefits. First, fighters fly much faster. Secondly, high octane gasoline is no longer a bottleneck. Third, Lower production costs. Fourth, Reduced vibration makes helicopters practical. Fifth, gas turbines replace finicky superchargers for high altitude flight.

Further benefits:
- no torque and it's reaction, so pilots are easier to train
- no prop needed
- jet fuel is less flamable
- tricycle U/Cs are mandatory, again it is easier for pilots to take off and land
- no syncronization gear for the guns needed

Fule consumption per mile travelled is tripled, though, so only 1- and some 2-engined designs?
 
The V-16 Db601 sized shaft would have been smaller than the V-12 DB603 based shaft. Even with a 33% length increase over the DB601 it would have still been no longer than DB603

Let's do a back-of-the-envelope math. Bore of the DB 601 was 150 mm. Disregarding the space between cylinders, on a V16 we need for each bank 150 mm x 8 = 1200 mm. Bore of DB 603 was 162 mm, for each bank it is 162 mm x 6 = 972 mm. Or, a V16 based on the DB 601 will demand some 25% longer crankshaft, camshafts, blocks and crankcase. It will also be more expensive to make, due to the greater parts count.

I'm not sure why pushing for a V16 (that, as an aircraft engine, nobody made to work well), while avoiding big V12s that worked well in several countries, and that were known quality well before ww2.

Fact is it was in production and they were preparing it for service. As it was it was a DB601E with bored out cylinders and a variety of improvements to handle the increased power.

Fact is that it was not in 'large-scale production', as claimed by M-B.
 

Deleted member 1487

Let's do a back-of-the-envelope math. Bore of the DB 601 was 150 mm. Disregarding the space between cylinders, on a V16 we need for each bank 150 mm x 8 = 1200 mm. Bore of DB 603 was 162 mm, for each bank it is 162 mm x 6 = 972 mm. Or, a V16 based on the DB 601 will demand some 25% longer crankshaft, camshafts, blocks and crankcase. It will also be more expensive to make, due to the greater parts count.

I'm not sure why pushing for a V16 (that, as an aircraft engine, nobody made to work well), while avoiding big V12s that worked well in several countries, and that were known quality well before ww2.
Why was the DB603 then 2.6m while the DB601 was only 1.7m? If we use your bore calculation there is only 72mm between 6 of the the DB601 and 603 cylinders. Clearly other parts added to the length of the overall engine and crankshaft besides the bore of the cylinders due to the power generated by the displacement.

Plus using your quote about the DB609 from before, the DB609 (the V-16 Db603) only gained 267mm over the V-12 DB603 despite adding 2 more cylinders per side. How would the V-16 DB601 then gain close to a meter in length over the base DB601 when the DB609 only gained a 11% greater length over the base DB603?
 
Why was the DB603 then 2.6m while the DB601 was only 1.7m? If we use your bore calculation there is only 72mm between 6 of the the DB601 and 603 cylinders. Clearly other parts added to the length of the overall engine and crankshaft besides the bore of the cylinders due to the power generated by the displacement.

FWIW:

DBs.jpg

Plus using your quote about the DB609 from before, the DB609 (the V-16 Db603) only gained 267mm over the V-12 DB603 despite adding 2 more cylinders per side. How would the V-16 DB601 then gain close to a meter in length over the base DB601 when the DB609 only gained a 11% greater length over the base DB603?

Indeed, there is plenty of details that determine the engine's length. Eg. the Chrysler IV-2200 (bore 147mm) was long between 120 and 130 in (3050 and 3300 mm), depending on the version.
 

Deleted member 1487

If the DB601E gained as much extra length as the OTL DB609 did over the DB603 then it would still be no longer than the DB603.

Indeed, there is plenty of details that determine the engine's length. Eg. the Chrysler IV-2200 (bore 147mm) was long between 120 and 130 in (3050 and 3300 mm), depending on the version.
Much longer than the DB609 because of the attempt to get around the crankshaft issue:
https://en.wikipedia.org/wiki/Chrysler_IV-2220
The extremely long profile of the new design meant that the crankshaft would be highly loaded if power was taken off at the propeller end. Chrysler's solution to this problem was unique; power was instead taken from the middle of the engine, placing the propeller reduction gear in a gap between two V-8 cylinder banks and sending power to the front of the engine via a long extension shaft running below the crankshaft. Additionally many of the accessories were driven off the drive shaft instead of the crank shaft. This solution also raised the weight of the engine by the amount of the shaft, but it was apparently a price worth paying.

A single overhead cam drove the two-per-cylinder poppet valves, arranged at an angle to the piston in a hemi-spherical cylinder head, with the spark plug arranged between the valves. This arrangement allowed for "cross-flow" scavenging of the charge, and had been used on various race and performance car engines for some time. The hemi is actually less efficient than the design being used in most engines of the era, the penta engine, which improved airflow by allowing three or four valves per cylinder.

One early problem for the design was the lack of high-strength aluminum alloys; the original supplier, Alcoa, was able to deliver only half the required strength. Chrysler was able to address this through much improved production-line quality control, but the engine was nevertheless built with considerably more distance between the cylinders than normal, making the engine relatively long. This was not helped by the "gap" holding the propeller gearing in the middle of the engine, or the large accessories section at the end.

Weight was not greatly affected, however, and the power-to-weight ratio was certainly competitive at 1.03 hp/lb.

So for a variety of reasons it attempted to get around the crankshaft potential issue by adding a lot more to the engine. That doesn't mean they couldn't have produced a crankshaft that would work, just that Chrysler decided to avoid the issue entirely at the price of making a very long engine.
 
If the DB601E gained as much extra length as the OTL DB609 did over the DB603 then it would still be no longer than the DB603.

I reckon it that you mean the V16 based on the DB 601 series would be shorter than the OTL DB 603? In case that 1200 mm suddenly became less than 972mm, it might be possible.

Much longer than the DB609 because of the attempt to get around the crankshaft issue:
https://en.wikipedia.org/wiki/Chrysler_IV-2220

So for a variety of reasons it attempted to get around the crankshaft potential issue by adding a lot more to the engine. That doesn't mean they couldn't have produced a crankshaft that would work, just that Chrysler decided to avoid the issue entirely at the price of making a very long engine.

People at Chrysler tried to adress the problem in design phase, they at least managed to have the IV-2200 power an aircraft for test purposes (too late to matter). People at DB were probably of the opinion that long crankshaft is actually not an issue when they design a light and powerful V16 engine for aircraft, designed the 609 accordingly, and canned it due to severe vibrations problems.

I'll try to point out, again, that people at different places of the world in 1930s-40s managed to succesfully design 35-45L V12s, produce them in large quantities and put into use, while V16s never flew a combat sortie, nor at least a training mission.
 
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I have little insight into the potential problems encountered with gas turbines IOTL, but were there not problems with them beyond those encountered for jet turbines?

Agreed, was the technology mature enough to allow this? And does Germany have the necessary raw materials?
 
I reckon it that you mean the V16 based on the DB 601 series would be shorter than the OTL DB 603? In case that 1200 mm suddenly became less than 972mm, it might be possible.



People at Chrysler tried to adress the problem in design phase, they at least managed to have the IV-2200 power an aircraft for test purposes (too late to matter). People at DB were probably of the opinion that long crankshaft is actually not an issue when they design a light and powerful V16 engine for aircraft, designed the 609 accordingly, and canned it due to severe vibrations problems.

I'll try to point out, again, that people at different places of the world in 1930s-40s managed to succesfully design 35-45L V12s, produce them in large quantities and put into use, while V16s never flew a combat sortie, nor at least a training mission.
Yet the Napier Sabre finally came through at 24 cylinders.
Seems like there must be solutions?
https://en.m.wikipedia.org/wiki/Napier_Sabre
 
Yet the Napier Sabre finally came through at 24 cylinders.
Seems like there must be solutions?
https://en.m.wikipedia.org/wiki/Napier_Sabre

Napier Sabre was a H24 engine, not V16. It sported two short crankshafts, each serving a bank of 12 opposed cylinders. So we have basically two opposed 12 cyl engines, one atop of the other, served by a common supercharger, oil, cooling and ignition system, sharing a carburetor, powering a common prop.
Note that Sabre was barely longer than 2 meters.

There were also H16 and H24 engines by Fairey, the H24 'Prince' was flight tested in the UK, and bench-tested in the USA. For the 'Prince' at least, each half, comprising of 12 cylinders' engines (for the H24) was independent, driving an own 3-bladed prop (for 6 blades total).
 
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