Thoughts on the K-4 Manouverability

[III/JG52_Otto_-I-]

On 8/11/2021 at 4:30 AM, gimpy117 said:

firstly, Lets get at what a 1940's "direct Injection" system is. it's essentially a timed pump that is to allow a squirt of fuel in at the proper moment (like a diesel). it's not computer controlled, it's noting like todays highly advanced direct injection systems. The Allied pressure Carb (throttle body injection) is really not that far behind in terms of fuel injection and can deliver fuel in an automatic rich or lean mode.

i think you have no idea about you are talking about.

The DB-601 and DB-605 had several system working together as mechanical computer, providing; automatic control of absolute inlet M.P. (manifold pressure), commanding the hydraulic unit of the supercharger.

The injection pump had a mechanical computer providing full automatic mixture control rich or lean as had required for M.P. and inlet air temperature.

 Allied presure carburators work like a single point injection, with lower performances than German injeccion system, even with allied better fuel.

The German's electric VDM  airscrew control system had centrifugal governor working as contant speed system. By the way allies P-51, P-39, P-47, etc used a simillar system named "Curtiss Electric"

On 8/11/2021 at 4:30 AM, gimpy117 said:

yeah allied aircraft never had auto radiator

As far as i know the Spitfire Mk IX and P-51D had automatic radiator shutters control.

Edited August 18, 2021 by III/JG52_Otto_-I-

[gimpy117]

2 hours ago, III/JG52_Otto_-I- said:

i think you have no idea about you are talking about.

The DB-601 and DB-605 had several system working together as mechanical computer, providing; automatic control of absolute inlet M.P. (manifold pressure), commanding the hydraulic unit of the supercharger.

The injection pump had a mechanical computer providing full automatic mixture control rich or lean as had required for M.P. and inlet air temperature.

 Allied presure carburators work like a single point injection, with lower performances than German injeccion system, even with allied better fuel.

The German's electric VDM  airscrew control system had centrifugal governor working as contant speed system. By the way allies P-51, P-39, P-47, etc used a simillar system named "Curtiss Electric"

As far as i know the Spitfire Mk IX and P-51D had automatic radiator shutters control.

 

yeah, and I'm supposed to be impressed? 

 

sounds like the mechanical gizmo controlled MAP by clutching the supercharger through a fluid coupler. Allies also had MAP controls...just not with what sounds really complex. 

 

Injection pump...so? so it auto mixture like a pressure carb. it's still a cam driven injection pump with a leaning system (like anything else) 

allied pressure carbs were indeed throttle body, but, in 1940's tech the gap was far less exaggerated then even 1980's tech. talking up a cam driven injection pump vs. a pressure carb is still just history channel German tech hype. It's marginally better. Hell 1950's Cessnas have multi port injection. it's not that special 

 

and you basically said nothing on the propeller system. the electric system is basically a worse slower constant speed system. you're swapping electrics for a crank case oil pressure system for prop pitch. there is a reason electric props are not around. and the allies drop the electric props because of that reason.

 

I'm sorry to beak it to you, but as an FAA A&P who works on aircraft for a living...that's where I stand. I will reiterate: any slight technical advantage is negated late war by overall poor engine and airframe build quality. you cannot make a precise airframe in a cave with slave labor. it's just not that easy. we do major upgrades and repairs to airframes. we spend days on engine beam replacements (or more)sometimes quoted at 30+ hours. the idea that a slave laborer with little training and substandard materials and equipment can make an aircraft to perform to calculated numbers is a stretch to say the least. Have you ever riveted? ever shaped sheet metal? have you ever built a part by hand to 1/32" standards? that kind of work is a true art form....the kind that has specialized "structure people" who are a sought after cadre in the A&P community. I've had trainign and I'm still garbage at it. so the idea that german build quality continued in my experience is pure self serving fantasy.   

Edited August 19, 2021 by gimpy117

[III/JG52_Otto_-I-]

13 hours ago, gimpy117 said:

Injection pump...so? so it auto mixture like a pressure carb. it's still a cam driven injection pump with a leaning system (like anything else) 

allied pressure carbs were indeed throttle body, but, in 1940's tech the gap was far less exaggerated then even 1980's tech. talking up a cam driven injection pump vs. a pressure carb is still just history channel German tech hype. It's marginally better. Hell 1950's Cessnas have multi port injection. it's not that special 

It is a shame to read that there is such a lack of training and aeronautical knowledge in a colleague, because I am also an aircraft mechanic.
Only i can tell you that, if you don´t know why and how important is the direct fuel injection in a aircraft supercharged piston engine, or what happen in a supercharged carburetted piston engine during valve overlap timing, it is enough motive for firing you. 

Moreover it seem that you don't know the difference between direct injection and port injection.


I highly recommend that you read Calum Douglas's book before continuing discussions about things in which you are not properly informed 

13 hours ago, gimpy117 said:

the electric system is basically a worse slower constant speed system. you're swapping electrics for a crank case oil pressure system for prop pitch. there is a reason electric props are not around. and the allies drop the electric props because of that reason.

One more time you are misinformed, because the fact of the propeller pitch system has been electrically or hydraulically controlled nothing to do with faster or slow it was. But hydraulically actuated propeller had great problems of oil icing inside the propeller hub, flying at hight altitude at cruise speed, because the hot oil almost didn´t recirculate inside the hub for hours. In 1942 USAAF decided improve all his modern fighters with electrical propeller pitch control... such as Germans had doing from 1937.

 

13 hours ago, gimpy117 said:

so the idea that german build quality continued in my experience is pure self serving fantasy. 

You missed the phrase... and Wernher von Braun never work for NASA  


 

Edited August 19, 2021 by III/JG52_Otto_-I-

[[DBS]TH0R]

On 8/8/2021 at 6:25 PM, III/JG52_Otto_-I- said:

Then imagine the quality in 1939 out of the cave.

By the way, the Allied "without caves" were not able to mass produced direct fuel injection engines, superchargers with hydraulic coupling (until 1944), like Bf-109 used from 1938 to war end in 1945,... or full automatic engine management device like BMW 801 "komandogerat".

Have you think about this?  ?

  

 

Since you've read the book by C.E.Douglas ... He clearly states the Allies misjudged the importance of direct fuel injection system before the war and this is the main reason why it entered production when it actually did. Only after they found out Germans were using it from the crashed He-111 (1939. in Scotland ; page 118. in the book) it became important to continue developing this tech.

 

Additionally, on page 101. there is a nice summary on how Allies benefited from higher octane ratings i.e. better fuels - for more even performance across the range from rich to lean mixture and less temperature dependent, with iso-octane rich fuels vs. high aromatic content fuels used by Germany.

 

On the following page (102.) he then concludes:

 

"This kind of control was almost impossible to attain with a carburetor, but the Allies had the advantage that their fuels had a much flatter fuel curve than the German aromatic fuels, and so their engines would require much less adjustment to run well in different temperatures, boost levels or air/fuel rations. If the German engines were to give performance near their maximum at all times, fuel injection with a highly sophisticated mechanical control system would be needed."

 

Basically it was a necessity to have a complex engine management device.

Edited August 19, 2021 by [DBS]TH0R
typos

[357th_Dog]

On 8/8/2021 at 9:25 AM, III/JG52_Otto_-I- said:

Then imagine the quality in 1939 out of the cave.

By the way, the Allied "without caves" were not able to mass produced direct fuel injection engines, superchargers with hydraulic coupling (until 1944), like Bf-109 used from 1938 to war end in 1945,... or full automatic engine management device like BMW 801 "komandogerat".

Have you think about this?  ?

  

Being unable to and not seeing the necessity of doing so are completely different things. 
 please try to be intellectually honest 

Edited August 19, 2021 by 357th_Dog

[III/JG52_Otto_-I-]

42 minutes ago, [DBS]TH0R said:

On the following page (102.) he then concludes:

 

"This kind of control was almost impossible to attain with a carburetor, but the Allies had the advantage that their fuels had a much flatter fuel curve than the German aromatic fuels, and so their engines would require much less adjustment to run well in different temperatures, boost levels or air/fuel rations. If the German engines were to give performance near their maximum at all times, fuel injection with a highly sophisticated mechanical control system would be needed."

 

Basically it was a necessity to have a complex engine management device.

So German´s "highly sophisticated" engines, "giving performances near their maximum at all times" were better or worse than Allies engines  with "less adjustment" wasting good fuel ?? ... Let´s be intellectually honest...as @357th_Dogsaid.  

[41Sqn_Skipper]

1 hour ago, III/JG52_Otto_-I- said:

One more time you are misinformed, because the fact of the propeller pitch system has been electrically or hydraulically controlled nothing to do with faster or slow it was. But hydraulically actuated propeller had great problems of oil icing inside the propeller hub, flying at hight altitude at cruise speed, because the hot oil almost didn´t recirculate inside the hub for hours. In 1942 USAAF decided improve all his modern fighters with electrical propeller pitch control... such as Germans had doing from 1937.

 

AP 2095 Pilot's Notes General, May 1941

[III/JG52_Otto_-I-]

5 minutes ago, 41Sqn_Skipper said:

AP 2095 Pilot's Notes General, May 1941

You have noticed how many American fighters had electrical pitch control in 1942 onward?

 

Spoiler

 

Edited August 19, 2021 by III/JG52_Otto_-I-

[[DBS]TH0R]

6 minutes ago, III/JG52_Otto_-I- said:

So German´s "highly sophisticated" engines, "giving performances near their maximum at all times" were better or worse than Allies engines  with "less adjustment" wasting good fuel ?? ... Let´s be intellectually honest...as @357th_Dogsaid.  

 

Let us be intellectually honest then.

 

On the same page (101.) he describes how engines running on aromatic fuels, in order to achieve max performance, had to be run with a rich mixture - whilst in lean the power drops 50% for cruising.

 

I applaud them for designing the automatic engine management device, but basically they had no other choice with the fuels at their disposal.

Edited August 19, 2021 by [DBS]TH0R

[III/JG52_Otto_-I-]

15 minutes ago, [DBS]TH0R said:

Let us be intellectually honest then.

 

On the same page (101.) he describes how engines running on aromatic fuels, in order to achieve max performance, had to be run with a rich mixture - whilst in lean the power drops 50% for cruising.

Page -102 of Calum Douglas´s book:
""March 30, 1939 ....Dairnler-Benz engineer Dipl.-Ing Hoffman had led the effort to coax a great deal of power from the DB 601 A engine by boosting it to 2.2 atmospheres above atmospheric pressure. The 33-litre engine reached an incredible 2500bhp.""

Edited August 19, 2021 by III/JG52_Otto_-I-

[[DBS]TH0R]

8 minutes ago, III/JG52_Otto_-I- said:

Page -102 of Calum Douglas´s book:
Dairnler-Benz engineer Dipl.-Ing Hoffman had led the effort to coax a great deal of power from the DB 601 A engine by boosting it to 2.2 atmospheres above atmospheric pressure. The 33-litre engine reached an incredible 2500bhp.

 

Please don't read selectively. Throughout the book various engines are mentioned being boosted to crazy power figures, up to +3000bhp. But for how long a service life?

 

Also mentioned several times, is a difference in building an engine for performance races such as Schneider Trophy which are hand built in small quantities by expert workers vs. those designed for the front line built by labor workers and mass produced in factories.

 

Here is a quote at the end of the mentioned page 101 in my last post:

 

Quote

The synthetic aromatic fuel gave exceptional engine performance but only at low air temperature and at fuel-rich air mixtures. Not only that, but the variation was far more extreme than that shown by fuels given their performance by iso-octane addition. The engine designer able to use iso-octanes to boost their fuel performance could be sure of good engine performance despite variations in air temperature and fuel mixture. The designer forced to use aromatics could only be sure of good performance under fuel rich conditions and had to allow for a drop in performance as high as 50% if the engine had to run lean, as would be the case in cruising. The Allied 100 octane fuel performance was based entirely on the addition of iso-octanes produced by the Alkylation of crude oil, a process first comercialised by the Ethyl Corporation in the USA. Germany had no such supply and found iso-octanes difficult to produce ih high volumes from hydrogenation.

 

Edited August 19, 2021 by [DBS]TH0R

[III/JG52_Otto_-I-]

 

8 minutes ago, [DBS]TH0R said:

Please don't read selectively.

You are not doing it? 

[QB.Shallot]

 

16 minutes ago, III/JG52_Otto_-I- said:

Page -102 of Calum Douglas´s book:
""March 30, 1939 ....Dairnler-Benz engineer Dipl.-Ing Hoffman had led the effort to coax a great deal of power from the DB 601 A engine by boosting it to 2.2 atmospheres above atmospheric pressure. The 33-litre engine reached an incredible 2500bhp.""

 

I'm a bit confused. What's the point of sharing information about engine tests with very high power outputs? Unless there's some super secret documentation that I haven't seen, none of those power settings (nor anything particularly close to them) were ever approved for service. Are you arguing about hypothetical aircraft configurations, or the frontline reality?

[[DBS]TH0R]

21 minutes ago, III/JG52_Otto_-I- said:

 

You are not doing it? 

 

Not sure I understand the question so my reply would be yes and no.

 

Yes as in an answer to things like mentioning a boosted DB 601 A engine, and no as in to put things into wider objective perspective which is what makes the mentioned book such a great read.

Edited August 19, 2021 by [DBS]TH0R

[III/JG52_Otto_-I-]

2 minutes ago, QB.Shallot said:

Are you arguing about hypothetical aircraft configurations, or the frontline reality?

My point is German aeroengines engeniering was better and more advanced than allied from before war started.
Despite of all evidences plublicated in books, it seem that all the forum still thinking that the poor quality of the German aircrafts (documented at the end of the war), was the same from the begining of the war. That not true. 
Moreover same as Germans, British and Americans have been industrial problems, and important engeneering faulties, many of these problem were solved copying German devices, such as, GM-1 (Nitrous oxide) injection used in the Mosquito, or MW-50 (Methanol-Water) injection used in P-47, Corsair, etc. 
@[DBS]TH0R he have the Calum Douglas´s Book, and he knows it. 

[[DBS]TH0R]

On 8/19/2021 at 8:31 PM, III/JG52_Otto_-I- said:

My point is German aeroengines engeniering was better and more advanced than allied from before war started.
Despite of all evidences plublicated in books, it seem that all the forum still thinking that the poor quality of the German aircrafts (documented at the end of the war), was the same from the begining of the war. That not true. 
Moreover same as Germans, British and Americans have been industrial problems, and important engeneering faulties, many of these problem were solved copying German devices, such as, GM-1 (Nitrous oxide) injection used in the Mosquito, or MW-50 (Methanol-Water) injection used in P-47, Corsair, etc. 
@[DBS]TH0R he have the Calum Douglas´s Book, and he knows it. 

 

There are some amazing engineering feats done by German engineers in the pre-war and during the war era. Marvels like direct injection, Jumo's crankshaft lubrication, hydraulic driven DB supercharger etc, roller-rocker cam design in DB (vs. oil film one in the Merlin) etc...

 

One major reason why it was advanced in the early war period was due to the fact unlike competition they basically had unlimited funds by the government, and we know why.

 

But the book also features their poor decision making and lack of sharing tech between the companies in the same country. Allies (USA and Britain) shared nearly everything whilst DB engineers and Jumo engineers didn't. For the example, DB 600 series would have benefited tremendously from Jumo's "10 years ahead of time" crankshaft lubrication design, and having DB supercharger would have enabled Jumo engines to be used in a single engine fighters. For this reason He-111 went from Jumo to DB and back to Jumo engines.

 

Then there is poor decision making (due to politics) in fuel distribution system and how it was stored and processed. Coupled with lack of rare metals which Allies had in abundance and forced them to use different solutions - which limited performance of spark plugs, valves and other engine performance vital parts.

 

All of this nicely describes engine design and decision making on both sides in the book we're talking about.

 

EDIT: I need to double check this in the book, but BMW's first (test) radial engines were license built P&W (IIRC) US ones.  There was a lot of tech shared between Allies and Germany before the war in academic publications which I found especially interesting. And how Germans deliberately hid the direction injection tech from Allied engineers visiting them shortly before the war.

 

 

 

On 8/19/2021 at 8:31 PM, III/JG52_Otto_-I- said:

Despite of all evidences plublicated in books, it seem that all the forum still thinking that the poor quality of the German aircrafts (documented at the end of the war), was the same from the begining of the war. That not true.

 

EDIT2: Just in case my post wasn't clear enough, engineers on both sides were very capable whilst German ones had to try harder due to lower fuel quality and lack of precious metals & other raw materials needed to build engines of the period. The reason why they had a head start is simple - gearing for war.

 

Poor quality vs. having to make do with lesser quality materials and fuel are two very different things.

Edited August 21, 2021 by [DBS]TH0R
typos, EDIT & EDIT2

[QB.Shallot]

@III/JG52_Otto_-I-

That’s fair, I don’t think a lot of people would argue otherwise, seeing as Nazi Germany was preparing for a global war while everyone else was idling around at interwar development rates. Beyond that, the results of the war speak for themselves. Despite all the fancy performance margins that could achieved in testing, they had zero bearing on the wartime reality. I don’t see where else discussion really goes, or how it got here from a 109’s turn rate. 

Edited August 19, 2021 by QB.Shallot

[CUJO_1970]

Otto you went and upset the Mustang Ranch. 
 

Some of them can read and even own books and at least one of them can change spark plugs in a Cessna, so tread lightly my friend and Godspeed. 

[41Sqn_Skipper]

2 hours ago, III/JG52_Otto_-I- said:

You have noticed how many American fighters had electrical pitch control in 1942 onward?

 

AP 2095 Pilot's Notes General 2nd Edition, April 1943

 

 

 

 

I'm not and US aircraft expert, so please correct me if I'm wrong. To my knowledge:

 

hydraulic propellers:

• P-51B/C/D
• Corsair
• Hellcat
• some P-47

electric propellers:

• Wildcat
• P-40
• P-38
• some P-47

To me that looks more like early mediocre US aicraft used electric propellers, while the later top class aircraft used hydraulic propellers.

 

[III/JG52_Otto_-I-]

1 hour ago, CUJO_1970 said:

one of them can change spark plugs in a Cessna,

well,.. i can change the spark plugs in a A320, A330, A340, A350, and B757. Where is the problem 

9 minutes ago, 41Sqn_Skipper said:

 

AP 2095 Pilot's Notes General 2nd Edition, April 1943

 

 

 

 

I'm not and US aircraft expert, so please correct me if I'm wrong. To my knowledge:

 

hydraulic propellers:

• P-51B/C/D
• Corsair
• Hellcat
• some P-47

electric propellers:

• Wildcat
• P-40
• P-38
• some P-47

To me that looks more like early mediocre US aicraft used electric propellers, while the later top class aircraft used hydraulic propellers.

 

AP 2095 Pilot's Notes General 2nd Edition, April 1943

You are refering to a RAF pilot´s General Manual.
I'm don't remember what British aircrafts had electric propeller pitch control in 1943. As i said in previous posts american used "Curtiss Electric" propeller. But probably British "ROTOL electric" were worse than american Curtiss. 

[41Sqn_Skipper]

1 hour ago, III/JG52_Otto_-I- said:

You are refering to a RAF pilot´s General Manual.
I'm don't remember what British aircrafts had electric propeller pitch control in 1943. As i said in previous posts american used "Curtiss Electric" propeller. But probably British "ROTOL electric" were worse than american Curtiss. 
 

 

The Pilot's Notes General also cover American aircraft that were in use by the RAF at that time. The quote is from the section that covers the Curtiss electric propeller, here's the full section:

 

If you read the other chapters in the Pilot's Notes General you see that specific aircraft, engine or propeller types are mentioned if they require some special handling compared to the general descriptions. For example:

 

If the slow response would be limited to the Rotol electric propellers it would be mentioned in paragraph (iv).
 

So far I haven't seen anything that supports the claim that electric controlled propellers were as quick as hydraulic propellers.

 

 

 

 

Edited August 19, 2021 by 41Sqn_Skipper

[gimpy117]

10 hours ago, III/JG52_Otto_-I- said:

It is a shame to read that there is such a lack of training and aeronautical knowledge in a colleague, because I am also an aircraft mechanic.
Only i can tell you that, if you don´t know why and how important is the direct fuel injection in a aircraft supercharged piston engine, or what happen in a supercharged carburetted piston engine during valve overlap timing, it is enough motive for firing you. 

 

well, yeah I never said a Cessna had direct injection. the injectors sit behind the intake valves in the primer holes. when I said multi port I meant Multi port IE: it has multiple port injectors. but please, split hairs and go for the ad hominem attacks. sure, maybe I'm guilty of poorly describing what I was trying to get across and yeah I'll admit I don't know everything under the sun. Nobody does. but hey...I'll try and be polite. I ask the same courtesy. 

 

I also think you're over stating the advantage that the early direct injection has over a pressure carb. and, especially when coupled with the poor fuels the Germans were running. I know what the advantage is sure, but like I said earlier, were not talking a modern direct injection system here...it's a cam timed pump (not the modern electrical injectors you posted pictures of, I know this because I found some photos of actual 109 injector systems...or at least what appear to be). also, I might point out that a Pressure carb IS NOT a traditional carburetor, it operates on positive fuel pressure, IE the throttle body injector. 

 

 

as to the actual maneuverability of the late 109's, I maintain my position that the build quality of the German 109's was so poor that almost certainly a large proportion of them would not perform to the calculated standards that have been used. It's why the freebie of using Hungarian aircraft was given. and what a courtesy it is.

 

Surely you know, as a fellow mechanic, one who has implied to have experience than me, that building structures is not an easy process and takes a lot of time and skill. you surely can agree, that an aircraft built in emergency factories and alternate sites with material cannot but up to the same standards as the preferred production. 

 

PS. who actually physically built the Apollo rocket though? ( familiar faces like: Boeing, North American Aviation (stages/command module), Douglas, IBM (instruments), Grumman (LEM)). it wasn't the  just Germans...an ARMY of engineers designed many systems. it was not done by von Braun himself...quite the opposite really. you are throwing out a re herring. 

Edited August 20, 2021 by gimpy117

[41Sqn_Skipper]

12 hours ago, III/JG52_Otto_-I- said:

many of these problem were solved copying German devices, such as, .... MW-50 (Methanol-Water) injection used in P-47, Corsair, etc. 

 

P-47D-10 test flight with water injection 11 October, 1943. Install instructions for aircraft in service February 3, 1944.

 

MW 50 tested in Bf 109 G-6/14 in May and June, 1944. Introduced in service June/July 1944?

 

 

[JtD]

First person to publish about water injection was the British engineer Harry Ricardo, some time in the 1920's. It certainly wasn't copied by anyone from anyone in WW2, it was common knowledge.

 

It is odd to see some try to summarize/generalize technical advantages in an as compact format as a forum post. Entire books have been written on several aspects of this subject and even these do not manage to paint the a complete picture.

[Kurfurst]

On 8/20/2021 at 9:48 AM, 41Sqn_Skipper said:

 

P-47D-10 test flight with water injection 11 October, 1943. Install instructions for aircraft in service February 3, 1944.

MW 50 tested in Bf 109 G-6/14 in May and June, 1944. Introduced in service June/July 1944?

 

DB 605G (later called DB 605A/m, DB 605AM, i.e. G14 engine) testing curves of 17 August 1943. BMW tested far earlier I believe, but choose different boosting methods in the end. 

 

http://www.kurfurst.org/Engine/DB60x/powercurves/DB605G_MW50_powercurve_viaGGH.jpg

 

For what its worth, Knoke's diary mentions his unit (JG 11) receiving MW 50 boosted G-6/AS in April 1944.

 

Regarding the ever present mantra of 'poor German aviation fuels', perhaps the following excerpt from the summary from 'Special Aviation Gasoline Report' prepared for FDR in March 1943of March 1943, arguing to develop and introduce 150 grade fuel for Allied warplanes to catch up with German developments, should be of interest.

 

 

 

Edited August 21, 2021 by VO101Kurfurst

[-=PHX=-SuperEtendard]

The statement about US planes being upgraded to electric control propellers also isn't correct. US fighters had electric propellers from early on, like in the P-40B, P-39D and F4F Wildcat. And then you had some transitioned to hydraulic propellers, like late variants of the P-39. And finally late war planes mostly used hydraulic propellers like the Merlin engined P-51s, F6F, F4U  and then the P-47 which used both types of designs with the Hamilton type being the best performing one (which was hydraulically adjusted).


 

[Kurfurst]

Electric vs hydraulic is a matter of design choice. The major difference is that generally speaking, hydraulics are able to exert more power (and can be therefore faster in pitch), while the major advantage of electric motor is that it is, well, electric: while to operate any hydraulic you need to have the engine running, while electrics can be operated from a separate power sources, a battery. Not an insignificant consideration in the event you have an engine failure, in which case you will also loose hydraulic pressure and cannot feather the prop for gliding. Electrics are probably more durable and less maintenance intensive, given that hydraulics can develops leaks and might be more sensitive to battle damage (on of the reason FW 190 went for all electrics).

[41Sqn_Skipper]

7 hours ago, -=PHX=-SuperEtendard said:

The statement about US planes being upgraded to electric control propellers also isn't correct. US fighters had electric propellers from early on, like in the P-40B, P-39D and F4F Wildcat. And then you had some transitioned to hydraulic propellers, like late variants of the P-39. And finally late war planes mostly used hydraulic propellers like the Merlin engined P-51s, F6F, F4U  and then the P-47 which used both types of designs with the Hamilton type being the best performing one (which was hydraulically adjusted).


 

 

 

23E50 = Hamilton Standard propeller

[[DBS]TH0R]

@VO101Kurfurst How was this "Grade 140" achieved? Lab testing differs greatly from real engine performance, especially back then since test engines usually were nothing more than single cylinder test beds. Presumably this was C3 fuel / high mixture grade, what was it's lean grade rating? Where could one obtain the full report?

 

There are various ways to calculate octane rating. Even today, you cannot compare the US and EU fuels for the same reason - people often think US has lesser quality fuel than EU, reality is they use different standard to calculate the value. But I digress...

 

 

On 8/21/2021 at 10:24 AM, VO101Kurfurst said:

Regarding the ever present mantra of 'poor German aviation fuels', perhaps the following excerpt from the summary from 'Special Aviation Gasoline Report' prepared for FDR in March 1943of March 1943, arguing to develop and introduce 150 grade fuel for Allied warplanes to catch up with German developments, should be of interest.

 

Greg here does a nice calculation and compares Allied fuels vs German B4 and C3 (goes through not just one but several Allied reports, and references C.E.Douglas and his book many times in the video):

 

 

 

The conclusion in the video is that later in the war (starting mid war) Germans started pushing their engines over what the B4 fuel can deliver. Thus the reliability issues arose. Not only that, but the very high compression ratios towards the war end are due to them pushing the engines even higher as service life wasn't important any more due to the average life expectancy of their pilots and planes. This was my conclusion even before I watched it to the end.

 

Greg here is in agreement with C.E.Douglas on how German fuels affected lean vs. rich mixtures, in context of engine tolerances of the time and various other factors as already mentioned metallurgy issues (lack of precious metals). All this further explains why and how Germany was hampered by lesser quality fuels vs. Allies. That plus the lack of intercoolers until late war unlike Allies that used them almost throughout the war duration*.

 

 

Spoiler

Harry Ricardo is being mentioned in the opening minutes, plus his importance and influence on WWII engine designs.

 

*EDIT:

 

Spoiler

The video also shows that even though late C3 fuel was capable of 125-130 octane rating per Allied tests, the German engines were not exploiting its higher octane potential based on Equivalent/Effective Compression Ratio (ECR).

For several possible reasons (or all of them combined):

1. metallurgy problems & lack of precious metals (hot spots & high exhaust valve temperatures = less resistance to knock)
2. lower quality oil towards the war end when this fuel was available
3. lack of intercoolers = higher inlet manifold temperatures
4. low evaporation rate when compared to Allied fuels (important in combination with 2.)

 

 

Edited August 23, 2021 by [DBS]TH0R
typos & EDIT

[gimpy117]

15 hours ago, VO101Kurfurst said:

 operated from a separate power sources, a battery. Not an insignificant consideration in the event you have an engine failure, in which case you will also loose hydraulic pressure and cannot feather the prop for gliding. Electrics are probably more durable and less maintenance intensive, given that hydraulics can develops leaks and might be more sensitive to battle damage (on of the reason FW 190 went for all electrics).

 

Not really. unless it was different back then, props use counterweights to feather the prop via inertia from a spinning prop. putting the prop into feather just lets all oil out and allows feather. leaks aren't really that bad. we mostly see seepage from the prop governor (due to seal age), but you have to monitor for seepage between the crank and the prop (also due to age). If you have a leak from a hydraulic prop from battle damage you have far bigger problems at hand since the oil is supplied from the engine, and that would mean the engine took a hit enough to stop oil pressure or knocked out the prop governor. either way you can throw the prop into feather.    

 

Edit: and, AFAIK the Hamilton standard system used counterweights to feather. 

Edited August 22, 2021 by gimpy117

[III/JG52_Otto_-I-]

On 8/20/2021 at 3:10 AM, gimpy117 said:

I also think you're over stating the advantage that the early direct injection has over a pressure carb. and, especially when coupled with the poor fuels the Germans were running. I know what the advantage is sure, but like I said earlier, were not talking a modern direct injection system here...it's a cam timed pump (not the modern electrical injectors you posted pictures of, I know this because I found some photos of actual 109 injector systems...or at least what appear to be). also, I might point out that a Pressure carb IS NOT a traditional carburetor, it operates on positive fuel pressure, IE the throttle body injector. 

 

You failed again because you have no idea about how a direct fuel injection work. 
You can learn a bit here: https://www.quora.com/Did-the-Luftwaffes-fuel-injected-engines-give-them-any-advantages-over-the-carbureted-engines-used-by-the-Allies
 

Quote

Francois Dovat,

Technical Writer at Auto-innovations.com (2003-present)

, ex-BMW Engineer · Author has 183 answers and 1.4M answer views

 

 

Did the Luftwaffe's fuel injected engines give them any advantages over the carbureted engines used by the Allies?

 

Yes! Other answers cite negative G capabilities, but that’s only one of the multiple advantages of direct injection.

Bosch in-line injection pump in a DB 601 (photo by me)

It allows more exhaust-intake valves overlap for a more complete scavenging, expelling residual gases without wasting fuel straight into the exhaust.

Direct injection also improves thermodynamic efficiency compared to carburetors and indirect injection. The fuel spray in the combustion chamber cools of the fresh charge of air, this being due to the change of liquid to gaseous state of gasoline. This cooling reduces detonation propensity, allowing to increase the compression ratio or boost pressure to improve thermal efficiency and/or increase power, especially in supercharged engines.

Direct injection reduces also wetting of the walls since gasoline is not introduced into the intake manifold. Walls at risk of wetting are limited to the cylinder and piston head, hot surfaces facilitating evaporation.

a) single point (trottle body) injection
b) indirect (port) injection
c) direct injection
(Image source : Combustion Process in the Spark-Ignition Engine with Dual-Injection System)

Fuel repartition between cylinders is much more precise than with carburetors or single point injection (“pressure injection carburetor”) as was implemented in the RR Merlin. The fuel mixing and air/fuel ratio are more accurate during transient phases (variations of load and revs). When the engine is cold, fuel evaporation and homogeneity are facilitated (finer droplets and higher temperature); thus cold start is easier.

The Allies had an almost unlimited amount of high octane fuel (100/130) while the Germans had to do with a restricted quantity of 87 octane fuel - and extremely rare 96 octane. Direct injection and later MW50 water-methanol injection allowed their engines to develop power levels similar to Allied ones. Some answers in What made the Rolls Royce Merlin engine so superior to all other engines? point out that the Merlin had only 27 liters displacement while the Jumo 211 / 213 had 35 liter, the DB 601 / 605 34 liter and 35.7 respectively and the big DB 603 44.5 liter.

But that’s irrelevant: the swept volume doesn’t matter, what does matter is engine weight and frontal area, which were very similar for Allied and German engines, the latter producing power levels of the same order with much lower octane fuel; moreover their specific fuel consumption was much less. The Merlin and identical US build Packard V-1650 as well as the Allison V-1710 burned 245 g/hp.h (330 g/kW.h), the French Hispano-Suiza 12Y 225 g/hp.h (300 g/kW.h) while the Junkers Jumo 211 / 213 and Daimler Benz DB 600 series were at 215-220 g/hp.h (290 g/kW.h) at take off or combat power and as low as 200 g/hp.h (270 g/kW.h) in cruising power at 2000 -2100 rpm.

The Jumo 213 J with 4 valves per cylinder (instead of 3) which were about to enter production at the end of the war developed 2250 hp @ 3700 rpm for take off with 87 octane fuel, and 2600 hp with MW 50 injection. After the war, the French company Arsenal assembled some Jumo 213 A from left out spare parts and tuned them for 100/130 gasoline. They pumped out 2300 hp @ 3250 rpm at take off.

Junkers injection pump (photo National Air and Space Museum)

Junkers manufactured their own injection pumps, in 150° V (both pictures above); the DB 600 series had in-line injection pump provided by Bosch while the BMW 801 were fitted with axial injection pumps made by Deckel.

The Deckel axial injection pump of the BMW 801

These systems remained a State secret that was only discovered in UK after a Heinkel He 111 H5 was downed near Edinburgh and landed with little damage on October 28th, 1939. One of its Jumo 211 A was dismantled and thoroughly analyzed while the other was tested on Rolls Royce’s test bench. The engineers were amazed by its performances; the secret of the German direct injection systems was simultaneously revealed.

Mechanical gasoline injection pumps (similar to diesel ones) are expensive high precision components. By the time the Allies were geared to mass produce them, the war was over and only post-war aero engines could be fitted with them.

The Bosch injection pump of the DB 603

Mercedes used Bosch direct injection again in its M 196 1954-55 racing engines, and soon after in the famous 300 SL.

Mercedes M196 with direct injection and desmodromic valves actuation.

Modern automobile engines are more and more often fitted with direct injection again.

 

Edited August 30, 2021 by III/JG52_Otto_-I-

[[DBS]TH0R]

Will not C/P every bit, but just the part where you highlight advantages of direct injection.

 

1 hour ago, III/JG52_Otto_-I- said:

Fuel repartition between cylinders is much more precise than with carburetors or single point injection (“pressure injection carburetor”) as was implemented in the RR Merlin. The fuel mixing and air/fuel ratio are more accurate during transient phases (variations of load and revs). When the engine is cold, fuel evaporation and homogeneity are facilitated (finer droplets and higher temperature); thus cold start is easier.

The Allies had an almost unlimited amount of high octane fuel (100/130) while the Germans had to do with a restricted quantity of 87 octane fuel - and extremely rare 96 octane. Direct injection and later MW50 water-methanol injection allowed their engines to develop power levels similar to Allied ones. Some answers in What made the Rolls Royce Merlin engine so superior to all other engines? point out that the Merlin had only 27 liters displacement while the Jumo 211 / 213 had 35 liter, the DB 601 / 605 34 liter and 35.7 respectively and the big DB 603 44.5 liter.

 

There are definitely benefits to having a direct injection. But not all was great because in those days they had no processing power to regulate fuel injection like we have today. As great as it was for the time - it did have its issues.

This is what C.E.Douglas has to say about DB engines, direct injection and C3 fuel (page 156.):

 

"The fuel designated C3, the only high-performance fuel it had been found practicable to produce in Germany, had a high boiling point. This meant that once it was absorbed into the oil in flight it stayed there, since the oil never became hot enough to boil the lighter fuel off. The problem of fuel being dissolved into the oil was (and still is today) a problem very particular to direct injection engines, which spray fuel directly into the cylinder. If this spray is not directed and atomized in just the right way, it cannot evaporate properly and can cover the wall of the cylinder with fuel. When the piston moves up, this fuel is entrained through the piston rings and down into the engine where it mixes into the oil circulating inside the crankcase. Once the proportion of fuel in the oil reaches a certain level, the oil stops functioning as an effective lubricant as it is too diluted by the very 'thin' fuel and the bearings quickly begin to fail. This was another serious disadvantage to not running hot-high-pressure cooling such as was being developed by Rolls-Royce for the Merlin; the German engine ran cooler - traditionally better for performance overall, but a disaster if the fuel could not evaporate out from the oil."

 

Agents such as Nitrous Oxide or "Göring Mischung 1" were very important for German engines for 2 main reasons:

1. could provide a cooling function to the combustion chamber
2. they were oxygen carriers as in to primarily increase high altitude performance

RR and other Allied engines had "dilute oil" for cold starts - because their fuels would evaporate once engine was running hot.

 

TL;DR: different engineering solutions with different benefits and limitations from each side.

Edited August 30, 2021 by [DBS]TH0R

[III/JG52_Otto_-I-]

4 hours ago, [DBS]TH0R said:

Will not C/P every bit, but just the part where you highlight advantages of direct injection.

 

 

There are definitely benefits to having a direct injection. But not all was great because in those days they had no processing power to regulate fuel injection like we have today. As great as it was for the time - it did have its issues.

This is what C.E.Douglas has to say about DB engines, direct injection and C3 fuel (page 156.):

"

Spoiler

The fuel designated C3, the only high-performance fuel it had been found practicable to produce in Germany, had a high boiling point. This meant that once it was absorbed into the oil in flight it stayed there, since the oil never became hot enough to boil the lighter fuel off. The problem of fuel being dissolved into the oil was (and still is today) a problem very particular to direct injection engines, which spray fuel directly into the cylinder. If this spray is not directed and atomized in just the right way, it cannot evaporate properly and can cover the wall of the cylinder with fuel. When the piston moves up, this fuel is entrained through the piston rings and down into the engine where it mixes into the oil circulating inside the crankcase. Once the proportion of fuel in the oil reaches a certain level, the oil stops functioning as an effective lubricant as it is too diluted by the very 'thin' fuel and the bearings quickly begin to fail. This was another serious disadvantage to not running hot-high-pressure cooling such as was being developed by Rolls-Royce for the Merlin; the German engine ran cooler - traditionally better for performance overall, but a disaster if the fuel could not evaporate out from the oil."

 

Agents such as Nitrous Oxide or "Göring Mischung 1" were very important for German engines for 2 main reasons:

1. could provide a cooling function to the combustion chamber
2. they were oxygen carriers as in to primarily increase high altitude performance

RR and other Allied engines had "dilute oil" for cold starts - because their fuels would evaporate once engine was running hot.

 

TL;DR: different engineering solutions with different benefits and limitations from each side.

Head of page 156 upward to paragraph that you cherry-picked

"""The fuel 3900 H, in terms of evaporation behaviour, is the worst, C3 is better, but still gives an unacceptable lubricant dilution. The old version C2 fuel, with a very low evaporation curve and an evaporation end point of around 125°, is absolutely faultless. Because of the poor detonation resistance of this fuel, which probably resulted from very long storage time, it is however now out of the question for the DB 601 N motor; besides, it is no longer Boeing produced ••• Conclusion: fuels 3900 H and C3 are unsuitable for use in the DB 601 N motor." ( dated in May 1940)


Pages 32 and 33 of same Calum Douglas book:

 

""" Morley was sent back to continue the tests but again he put off development of the automatic control and flight testing a fuel-injected aircraft. By September 1936, he had completed his reports on direct injection and high valve overlap and reported back to the DSIR panel:
"In view of the scavenging obtained by employing a large valve overlap when supercharging, and the possibility of preventing the direct passage of fuel into the exhaust by using a suitably timed injection system, experiments have been made on a single-cylinder air cooled unit with different amounts of valve overlap, to compare the performance on normal carburation with that using direct fuel injection."
A German fuel pump made by Bosch was used by Morley, set to a moderate average fuel pressure of 50 atmospheres.
Immediately visible was a large reduction in cylinder temperatures when using high valve overlaps with fuel injection...

The benefits of reducing cylinder temperature with higher overlaps seem not to have taken place with a carburettor; Morley could not explain this but claimed the proximity of the temperature sensor to the fuel injection nozzle had possibly skewed his results. In reality it was far more likely that the still burning fuel sent up out the exhaust ports by the carburettor (which was feeding in fuel continuously, even during the overlap period) heated the valves and cylinder head enough to negate the cooling provided by the extra airflow over the exhaust valves during overlap."""

Edited August 31, 2021 by III/JG52_Otto_-I-

[LukeFF]

What does this all have to do with the maneuverability of the K-4?

[III/JG52_Otto_-I-]

11 hours ago, LukeFF said:

What does this all have to do with the maneuverability of the K-4?

Several users here in previous posts are trying to justified the abnormally controls stiffening at combat speed, in the K4 that we feel in game, dropping bricks cherry-picked from several books, authors, etc. arguing "bad quality" of Germans designs, engines, fuels, workers sabotage, etc . I'm trying to explain that these things are relative to specific dates, and did not affected to maneuvreability of the airplane.

 

The real K4, G6-ASM (G6 "Late" in game), G-14 and G-10, had same handling characteristics at combats speeds, 300 to 500 kph. ..and we don't feel this in game.

[[DBS]TH0R]

I omitted the C2 part since (someone correct me if wrong) it isn't a synthetic fuel, thus wasn't mass produced during the war = irrelevant. Or in other words, fits into "what if" scenario.

 

@LukeFF no more OT from me. I'm done.  

Edited August 31, 2021 by [DBS]TH0R

[III/JG52_Otto_-I-]

6 hours ago, [DBS]TH0R said:

I omitted the C2 part since (someone correct me if wrong) it isn't a synthetic fuel, thus wasn't mass produced during the war = irrelevant. Or in other words, fits into "what if" scenario.

 

@LukeFF no more OT from me. I'm done.  

It depends that you called "mass produced" because until 1941, about 20% of German gasoline was "natural" from foreign oil refineries.

P.S.

I 've post this O.T. only for correct you as you asked. ?

[[DBS]TH0R]

Thanks for confirming C2 was not synthetic. By 1941 the stock pile gathered before the war and its pipeline (pun intended) had all but dried up, so B4 and C3 fuels were what was available. I am just not sure what and how important this is in relation to the mid to late war 109s like K4. But I am happy to find out in your next reply. ?

 

[III/JG52_Otto_-I-]

On 9/1/2021 at 6:27 PM, [DBS]TH0R said:

Thanks for confirming C2 was not synthetic.

have i ever denied it? .. I'm starting to think that you've never understand what we're talking about.

[[DBS]TH0R]

5 hours ago, III/JG52_Otto_-I- said:

have i ever denied it? .. I'm starting to think that you've never understand what we're talking about.

 

No, I haven't said that. I was unsure whether it was or wasn't pure synthetic like C3. The main difference being it was more of a "racing fuel" from what I was told and was able to find out after the last few posts here.