Extended use of full engine power

[mikey117us]

this is the Translated U-Boat Standing order No. 29
Permanent Order No. 29.

Full speed of main Diesel engines at sea.

During any enemy operation, cruise at full speed with both Diesels every four days for half an hour, while observing cruising times in order to detect signs of engine trouble immediately and to safeguard the full use of the boats fighting capacity when opportunity arises.

C.C. U-boats Top Secret 02809/FS of 28/1/43.
So in Reality Full Speed was War Emergency Power and AK+1 (we can't do in sh3) is Flank Speed with the Electric Motors and Batteries Tied In. And Running at full speed was necessary in the parameters above. But Long Term Running was a recipe for a Broken Boat.

[Leandros]

Originally Posted by mikey117us

this is the Translated U-Boat Standing order No. 29
Permanent Order No. 29.

Full speed of main Diesel engines at sea.

During any enemy operation, cruise at full speed with both Diesels every four days for half an hour, while observing cruising times in order to detect signs of engine trouble immediately and to safeguard the full use of the boats fighting capacity when opportunity arises.

C.C. U-boats Top Secret 02809/FS of 28/1/43.
So in Reality Full Speed was War Emergency Power and AK+1 (we can't do in sh3) is Flank Speed with the Electric Motors and Batteries Tied In. And Running at full speed was necessary in the parameters above. But Long Term Running was a recipe for a Broken Boat.

Diesels + electric? That ought to be a nice modding mission.....

As for permanent order no. 29 I should think it a particularly good idea to run the diesels up at intervals if run for longer periods at economic cruise (langsam fahrt). Diesels do have a tendency to "dirty up". One experience the same in diesel cars which have been "lady-driven".

If I run the diesels on my old minesweeper on idle for long periods it starts to emit a sort of oily "drops" from the funnel. Goes away when pressing it somewhat.

Fred

[GJO]

Originally Posted by Leandros

Diesels + electric? That ought to be a nice modding mission.....

As for permanent order no. 29 I should think it a particularly good idea to run the diesels up at intervals if run for longer periods at economic cruise (langsam fahrt). Diesels do have a tendency to "dirty up". One experience the same in diesel cars which have been "lady-driven".

If I run the diesels on my old minesweeper on idle for long periods it starts to emit a sort of oily "drops" from the funnel. Goes away when pressing it somewhat.

Fred

Thank you Fred - you have provided an answer to a real life situation that we have had for some time. The old Kelvin diesel on our boat does just that after extended inland waterway runs at >250 rpm (I often get covered in small droplets of black oil from the diesel exhaust!) and it needs a real blast at 500+ rpm every now and then to clear it.
I believe that similar orders about the management of diesel engines were issued to German tank crews.

[Leandros]

Originally Posted by GJO

Thank you Fred - you have provided an answer to a real life situation that we have had for some time. The old Kelvin diesel on our boat does just that after extended inland waterway runs at >250 rpm (I often get covered in small droplets of black oil from the diesel exhaust!) and it needs a real blast at 500+ rpm every now and then to clear it.
I believe that similar orders about the management of diesel engines were issued to German tank crews.

Another issue in this context might be the visibility at sea of the exhaust fumes.

Fred

[GJO]

Originally Posted by Leandros

Another issue in this context might be the visibility of the exhaust fumes.

Fred

Indeed, according to my father (who was in the Royal Artillery HQ section during the Normandy landings) that was how they spotted the German tanks - it soon became known that (in his words) "The 'Jerry' would punctually start all their tank engines at the same time every morning and run them fast initially sending up clouds of dirty smoke and this gave the gunners the range and target" - the range was calculated with a stopwatch by comparing the time elapsed between sighting the initial exhaust smoke and then hearing the noise. Possibly a case where the renowned German punctuality was not such a positive asset . . .

[GreyBeard]

Originally Posted by mikey117us

this is the Translated U-Boat Standing order No. 29
Permanent Order No. 29.

Full speed of main Diesel engines at sea.

.........cruise at full speed with both Diesels every four days for half an hour, ...........

But not flank speed. I always found that confusing. Why is it called full speed when it is not really full speed, but flank speed is?

[Leandros]

Originally Posted by GreyBeard

But not flank speed. I always found that confusing. Why is it called full speed when it is not really full speed, but flank speed is?

Ok, I am with you on this one - "full speed" is, I believe, something you can live with for a reasonable time while flank speed is really a sort of emergency effort. It was the same with aircraft piston engines at the time. 5 minutes was often set as a maximum but some engines could take it better than others. In a deplasement boat it really means very little regarding what you get out of it. When you have reached the ideal hull speed it takes so very much to increase it. In a aircraft it did, as in a climb with already reduced speed. In aircraft engines it was often coupled with water-methanol injection from a separate fuel tank. The Griffon engines in the Typhoon and Tempest were known to be more sensitive to overboost than, say, the Rolls-Royce or Allison V-12 engines. Simply because the Griffon was more powerful.

Fred

[Maltadog]

<pedantic_mode>
The RR Griffon engine was build in late spitfire versions (Mk XIV mostly).

The engines which powered the Hawker Typhoon and Tempest were variants of the Napier Sabre.
</pedantic_mode>

[Leandros]

Originally Posted by Maltadog

<pedantic_mode>
The RR Griffon engine was build in late spitfire versions (Mk XIV mostly).

The engines which powered the Hawker Typhoon and Tempest were variants of the Napier Sabre.
</pedantic_mode>

Whatever.......

Literature on the P-40 with Allisons in combat also frequently describes using an overboost function. It is usually stated to be used for max. 5 minutes.

Fred

[GreyBeard]

Originally Posted by Leandros

Ok, I am with you on this one - "full speed" is..............Griffon was more powerful.

Fred

Thank you for the explanation, now I get it. Back in the early `80's a few Formula 1 race teams began using engines that became know as qualifying grenades. Their hp was increased so much that they lasted 2/3 laps before "grenading" themselves. They were essentially the "flank speed" of Formula 1 engines. They were outlawed because not all teams could afford them.

[the dark knight]

Just a heads up guys, German tanks in WWII ran on high octane gasoline. The only country using Diesel's in tanks was Russia. The reason most people think German tanks were Diesel is because, unlike the Sherman, they did not burst into flames when a shell pierced the armor. The Germans, unlike the U.S.A., had the fuel tanks isolated in their own compartments, so spilt fuel, or a ruptured fuel tank was less likely to catch fire on hot exhaust pipes.

I have read that Germania built engines in the Type VII would spin a bearing, or throw a rod if run at high speeds for very long. On the other hand, having a M.A.N. engine was a blessing. I have heard they were better built, and made more power at the same RPM as the Germania Werft engines. So perhaps it boils down to a few things; engine manufacturer, how the engines have been taken care of (maintenance), and number of hours on the engines them selves.

[Leandros]

Originally Posted by the dark knight

Just a heads up guys, German tanks in WWII ran on high octane gasoline. The only country using Diesel's in tanks was Russia. The reason most people think German tanks were Diesel is because, unlike the Sherman, they did not burst into flames when a shell pierced the armor. The Germans, unlike the U.S.A., had the fuel tanks isolated in their own compartments, so spilt fuel, or a ruptured fuel tank was less likely to catch fire on hot exhaust pipes.

I have read that Germania built engines in the Type VII would spin a bearing, or throw a rod if run at high speeds for very long. On the other hand, having a M.A.N. engine was a blessing. I have heard they were better built, and made more power at the same RPM as the Germania Werft engines. So perhaps it boils down to a few things; engine manufacturer, how the engines have been taken care of (maintenance), and number of hours on the engines them selves.

Good info. To add to the last paragraph. In German S-boats the Daimler-Benz diesels were considered better than the MANs. They could take higher pressure for longer periods. But, here I should think we talk about much higher revolution numbers than in sub diesels. The S-boats delivered with MANs were eventually organized in a separate unit.

Another interesting comparison: the American Pratt & Whitney (Twin Wasp) and Curtiss Wright (Cyclone) radial engines. Both were offered in fighters before the war. For some reason the Cyclone proved much less reliable than the Twin Wasp. In bombers, however, there was little difference. Obviously depended on the use of the engine, the Cyclone used oil excessively in fighters. The Finns remedied this by installing the piston rings upside-down from the factory recommendation.

Fred

[Marcello]

Originally Posted by the dark knight

Just a heads up guys, German tanks in WWII ran on high octane gasoline. The only country using Diesel's in tanks was Russia. The reason most people think German tanks were Diesel is because, unlike the Sherman, they did not burst into flames when a shell pierced the armor. The Germans, unlike the U.S.A., had the fuel tanks isolated in their own compartments, so spilt fuel, or a ruptured fuel tank was less likely to catch fire on hot exhaust pipes.

Fuel use is a somewhat complex issue, the japanese and the italian medium tanks (to the extent they could be called such) used diesel engines too and the large fleet of soviet light tanks and derivates ran on gasoline. That said Sherman brewing up is likely more a result of pretty much nearly every german tank/antitank gun they ran into being able to punch throught them in first place, while peppering Panthers with 75mm would not be equally productive. Ammunition storage, probably the most important fire hazard though gasoline certainly does not help, was eventually rearranged.
In regards to submarine engines overheating would also cause issues with the exhaust system, which is a bit more critical than on a land vehicle.

[the dark knight]

Good points guys.

I know many assume that German tanks ran on diesel. It is a very common myth. The main disadvantage of a diesel engine is the high weight involved with it vs the German Maybach engines, that used roller bearings on the mains, and a very light engine.

I forgot all about the S-boots to be honest with you! Heat can be an issue for sure. I know that the IXD1 used the engines from an S-boot to make a high speed sub on the surface, but the heat and white smoke they emitted was really bad for them. I found this segment most interesting from the study of German type IX's after the war-

http://www.uboatarchive.net/DesignSt...eIXC-S41-5.htm

[GJO]

Originally Posted by the dark knight

Just a heads up guys, German tanks in WWII ran on high octane gasoline. The only country using Diesel's in tanks was Russia. The reason most people think German tanks were Diesel is because, unlike the Sherman, they did not burst into flames when a shell pierced the armor. The Germans, unlike the U.S.A., had the fuel tanks isolated in their own compartments, so spilt fuel, or a ruptured fuel tank was less likely to catch fire on hot exhaust pipes.

>snip<

I am sorry if I inferred that WWII German tanks had diesel engines. At the time, I doubt if the average British gunner would have known the difference anyway. The smoke on starting up was probably from valve gear and upper cylinder lubricating oil. I guess the exhaust (and noise) was minimal compared to firing up an L60 engine as used in the 1970s Chieftain tanks. Incidentally, the ARS (Army Rumour Service) always held that the L60 (and this was a compression ignition engine) was derived from a German WWII design.

As a matter of general interest one of the things that my father remembers most about the German equipment that they overran during the advance from Normandy is that it was extremely antiquated - they encountered very few items of modern armour and a very high proportion of the German artillery and support transport was horsedrawn - the smell of dead horses haunts him to this day. The reasons for the latter could have been due to fuel shortages or the fact that the German high command had been taken by surprise but I think things would have been a lot tougher if they had deployed significantly more modern tanks.

By the way, while working in REME workshops, I enjoyed the privilege of working on Rolls Royce Meteor engines which were, IMHO, one of the best tank engines of the era.