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AMP NEWS / Re: U 47 / Guenther Prien book
« Last post by falo on Today at 03:03 AM »
Hi Dougie,

thanks for the detailed information, afaik the film got no good critics at all here in Germany. I have watched this movie a few years ago on DVD and the whole subplot which stylized G. Prien to a resistance fighter against the nazi regime was pure fiction.

I wish your book a high sales numbers.

Best regards
AMP NEWS / Re: U 47 / Guenther Prien book
« Last post by dougie47 on 19 Oct , 2018, 14:21 »
Hi Falo,

Thanks for your comments. I wrote a couple of pages covering that movie in my book. It is quite watchable but historical accuracy takes second place on more than a few pages, sometimes being unintentionally funny.

Just for the record, Prien did not get a head injury by a piece of the Royal Oak in Scapa Flow (see blood on his temple at 41:49). Nor was U 47 a Type II (9:29), or a Type IX (9:33) or U 99 (9:54). Nor was Prien killed by his former First Watch Officer (sorry to spoil the ending!).


AMP NEWS / Re: U 47 / Guenther Prien book
« Last post by falo on 19 Oct , 2018, 07:23 »
Hi Dougie,

godspeed for your book. By the way: In 1958 the "Arca-Filmproduktion" made a film version of Gunther Prien. You can watch it in full length on Youtube (afaik no engl. dubbing available).

Best regards
The starting procedure of a smaller MWM diesel seems to be a bit cumbersome, but in principle correct. On a VIIC GW engine you use the electric stand by lubeoil pump to put up the lubeoil pressure before turning, then you turn the engine by air with open indicator cocks, blow trough as we called it, before the starting procedure.

Hello Mr. Tore,

This video shows a German Diesel engine and other components clutch and generator at the end of the video...

It looks like at the beginning the one person is pumping lube oil through-out the engine before starting with compressed air. I believe they started the Diesel engine with the clutch engaged and connected with the generator.

Panel line transfer

The next task was to mark all the panel lines on the two hull halves with a view to the scribing. Again I had an eye on the drawings of Koehl and Roessler as mentioned before. Though I omitted the three torp doors because I want to show them in a open position and for that purpose I opted a laser cut solution so a vector drawing was required based on Koehl and Roesslers drawings. Jobwise I use Adobe Illustrator for vector drawings so this was not a big deal, learn more about that in the next post.

I marked the hull cutouts for the photo etch parts with a felt pen. Some cutouts had to be positioned directly on the in a further mentioned cheeks. To saw out these cutouts from the DiBond cheeks was very time consuming because the material has three layers: Aluminium a kind of black rubber (high-density) and again aluminum. The aluminum was difficult to saw out and sand. The rubber core frayed during sanding and slowed down the saw blade nearly to halt. As I said a post before the DiBond material was ideal for bending the cheeks in a rounded form but rework would be needless if I had chosen plastic sheet for that task. Learning never stops.

Best regards.
Below is a revised scheme of the starting system may be it clarifies the system a bit better.  As to your concern of the combustion gases entering the starting air vessel I dont think it is a problem as the starting air cams are timed to open the starting valve at an optimal piston position past the TDC during the compression expansion stroke when the cylinder pressure is lower than the starting air pressure (30kg/cm2). There is no fuel supply at this stage. However when you are moving the fuelhandle towards fuelsupply you are at the same time venting the upper part of the starting valve and the startingvalve pushrod  is removed from the camshaft and the valve is shut by the spring.  Some times you obtain a supercharging effect by the starting air. Furthermore as far as I remember the startingair supply valve is a NR valve. This starting system is very conventional and is even today operated in thousands of dieselengines.

On some simple semidiesels you actually fill the starting air vessel by the combustion gases allowing same to enter by the starting air pipe.
I once had an incident where due to a mechanical failure  the starting valve stuck open. The result was overheating of the pipe, not very dramatic, only some brown coloured paintings.
Hello Mr. Tore,

Does this writeup look OK? Note there is a time period where fuel is injected when the starting valves are operational. Again was there an issue with cylinder chamber back pressure gases into the compressed air canisters?


Procedure For Starting The Diesel Engine With Compressed Air

1. Opening the starting air valve (RED Hand-wheel) and admitting starting air into the lower part of the starting air valve provides compressed air to the starting manifold and the starting valves. There are six (6) starting valves; one (1) per cylinder.

2. Moving the starting handle to the start position directs compressed air from the starting manifold to the top of all six (6) starting valves. This air pressure forces all six (6) guide links to pull upward and cause the cam arm rollers to engage the starting cams.

3. One of the six (6) cams will be at a low position and the guide link will move higher and force the starting valve to open and admit starting air into the cylinder chamber and force the piston in a downward direction. This piston movement starts the crankshaft rotation whereby other starting valves will continue this running on compressed air process.

4. After the required RPM is reached, move the left fuel handle from stop to a point beyond 0 the minimum (the maximum is 55) and then ignition occurs. Now, move the right starting handle to operate which results in the roller cam arms being lifted off the cams and the compressed air being vented at the starting manifold into the diesel room. Turn off the starting air via the RED hand-wheel on the starting air valve. At this point, the diesel engine will be run-up until the operating temperature is achieves and then put on-line at the commanded speed.

Shutdown move the left fuel handle up from the amount of fuel to Stop.

In the photo of U-995s right starting handle, it only has two (2) positions; run [at the top (Betrieb)] and start [at the bottom (Anlassen)], and the reason for this difference is because U-995 diesel engines do not have reversing. If it did have reversing, then there would be a reversing handle to the right of the starting handle as I have indicated in the modified photo. However, on U-995 if there was a need for reversing, then the e-motors will be used for that function. If there is a lack of compressed air to start the diesel engines, then they could use the e-motor to crank the diesel up to speed and then inject the fuel for ignition.
AMP NEWS / U 47 / Guenther Prien book
« Last post by dougie47 on 15 Oct , 2018, 15:57 »
Hello folks,

I would like to announce that my book "Guenther Prien And U-47: The Bull Of Scapa Flow" will be released in Europe on Wednesday 17th October by Frontline Books -

This will be available in various places including Amazon -

It will be available in North America and Australia on 1st November via the publisher US Naval Institute Press. This is the same book, just different publishers for different regions of the world.

Some of you will know that I have been working on this book since the dawn of time. I finally finished it, though working on other book projects, AMP business and of course making models somewhat slowed the process down. A few of you are in the acknowledgements list.

Amazon lists it as 360 pages but it has 450 pages.

For those of you who don't already know, U 47 was commanded by Guenther Prien, who is one of the most important of all U-boat commanders. Doenitz even referred to him as "our best commander". His boat was U 47, which he commanded for ten patrols until he and his boat were lost in March 1941. Both Prien and his boat were referred to as The Bull Of Scapa Flow after the daring sinking of HMS Royal Oak at Scapa Flow in October 1939. 

Part I has an introduction on the Battle of the Atlantic.

Part II is the patrol and refit history and is essentially a book in itself. It charts in chronological order all ten patrols and all the modifications in the refits. This took years to complete as the section was written with multiple sources including reference to all of U 47's original war diaries. Since it follows what Prien wrote in his diaries I hope it gives a feel for his view of their actions in the Atlantic. There are plenty of passages about frustration at missing convoys in heavy seas, encountering British warships in the North Sea, being attacked by RAF aircraft, moving stealthily around Norwegian fjords, frustration at torpedo failures, and of course the night surface attacks inside the convoy along with other aces. Jerry Mason was particularly helpful to me in kindly translating several war patrols for me. It ends with a discussion of the possible reasons for the loss of the boat.

Part III begins the second half of the book and covers the Scapa Flow raid in detail. Part IV is an entire section dealing with the various controversies surrounding the raid. Several books have been written on this subject but I have tried to go beyond these and answer all the remaining questions. I have chosen 41 controversial aspects; for each of these I have asked the question, had a discussion and then formed a conclusion. At the end I have listed over 20 new findings not covered in other works.

Part V ends the book and covers Prien and the crewmen of U 47.

My sincere thanks to everyone who assisted me over the years in writing the book. I got there...finally!


Dougie Martindale
Accurate Model Parts

Just to let you know. The new Das Boot teasers were released an hour ago. You can find them here.
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