Looking for Bf 109 G Start&Notleistung duration

[Yew Staff]

A question please. How is the 10 hour brake in time to be achieved?

this is actually the process of flying in the engine with the aicraft it is attached to for regulating Purposes before released for frontline service
additional to the bench run in process

 

[Engineman]

Thanks. I couldn't believe a new engine, with only a few hours, would make takeoffs and still try to keep a good brake in.

So, the testing and acceptance of the DB 605 engines was quite a complex task. Examination of all the orders for the production testing is incomplete in my data. However, there are many details that we do know. Overall, the testing of newly built engines changed over the production of the DB 605. Initially, there was a program of very detailed tests of the engines after build. These tests could include partial rebuilds just during the tests. I do not have a copy of the very early test program. The first version I have is the May 1943 version that is the build standard 9-605-6080. This program starts with Electric driven turning of the engine for a period of 2 hours, followed by the general testbed running with Gas (75%Butane+25%Propane) for 2 hours and then a final period including acceptance with the fuel injection and B4 fuel of 3 and 1/2 hours.
The next standard is dated November 1943, 9-605-6094. This includes the initial 2 hours turning with either Electric drive or Gas fuel, followed by more running in the power range including 2800/1.42 with gas for about 2 and 1/2 hours, and finally with B4 fuel and Injection pump etc, the acceptance run of 1 and 1/2 hours.
Unfortunately, the precise procedure remains a little obscure but, it seems that a standard engine had about 6 hours of running before completing testing and BAL acceptance. This is not to say that the detailed requirements are not listed, the Prufdaten is very specific about the power settings and times, but the exact requirements of production testing are tricky to tell.
Next, I do not have copy of "Durchführung des Einfliegens von 10 Stunden entsprechend TAGTTIC 6., Nr. *, lfd. Nr. 705/43" to confirm the details but, this would seem to apply to the initial flying use of the engine that is listed in the Bf 109 G2, G4, G6 Aircraft Handbook, June 1943.
New and overhauled engines, Fly-in gently. For the first 1-hour flight, do not exceed 2100/1.05 after Take-off .
Then until 5 hours of flight, not more than 2300/1.15.
Then for next 5 hours of flight, not more than 2600/1.30.
After 10 hours, within the applicable regulations for engine use.
So, the Take-off would be made with power as required and then, limited as listed.

Eng

 

[Snautzer01]

Were the engines mated to the plane or on a test construction.?

 

[Engineman]

Were the engines mated to the plane or on a test construction.?

The post-build/overhaul testing and acceptance would all be done on test stands. The production test stands were not always very refined, not all the fancy techno types with glass windows. When the test was passed, the BAL Inspector would issue the approval paperwork and the engine would be prepared for transportation to the RLM/Luftwaffe distribution system. By far the most new engines would go to the aircraft factories for installation on new aircraft. The Break-in flying time began with the post build test of the new aircraft, or the in-service fitting of a new/overhauled engine at a forward unit, the "10 hours" is specifically listed as flying hours.

Eng

 

[Engineman]

Were the engines mated to the plane or on a test construction.?

It is a lot of work just to process and despatch these engines. Just take the DB Genshagen output of DB 605 engines in June 1943 to May 1944:
J 566, J 469, A 359, S 459, O 578, N 390, D 587 / 1944, J 500, F 640, M 730, A 862, M 851.
That is around 20 engines dispatched a day, every day of the week from a single large factory.
All the large factories, Allied and Axis were churning materiel out.

Eng

 

[Snautzer01]

If the breaking in and testing were done at the factory and ot was bombed that would be a big bonus i think.

 

[special ed]

All of this is most interesting. In the late 1950s &60s when my interest drifted to big car engines, I read as much as I could about brake in after new or rebuilds. In 1969, my first new car received much of what I learned, such as three oil changes during the first 500 miles as well not running at steady speed for long periods. The using of deceleration though the transmission to keep oil flowing with rpm rather than idle. The actual results are not provable, but it ran well compared with others with larger engines. By 1973 when my first mistake left, the 69 was the one of my five cars she wanted.
On another note, the current brake in technique for model engines, .06cc thru 10cc is to run the new engine in reverse direction slowly, plenty of lube, using an electric drill and a test stand about 100 revolutions. The racing crowd so says. Being an old person, I still run the new engine very rich on a test stand a few minutes at time allowing cooling to allow the metal to adjust. After 20-30 minutes it goes on a plane for some rich runs until it is happy.

 

[Engineman]

If the breaking in and testing were done at the factory and ot was bombed that would be a big bonus i think.

Yes, the engine factories were hit but, often the heavy machinery did survive being bombed and, there was a lot of dispersed production.
I think the crankshaft production at Krupp etc was a weak point but, that is another subject.

Eng

 

[Engineman]

All of this is most interesting. In the late 1950s &60s when my interest drifted to big car engines, I read as much as I could about brake in after new or rebuilds. In 1969, my first new car received much of what I learned, such as three oil changes during the first 500 miles as well not running at steady speed for long periods. The using of deceleration though the transmission to keep oil flowing with rpm rather than idle. The actual results are not provable, but it ran well compared with others with larger engines. By 1973 when my first mistake left, the 69 was the one of my five cars she wanted.
On another note, the current brake in technique for model engines, .06cc thru 10cc is to run the new engine in reverse direction slowly, plenty of lube, using an electric drill and a test stand about 100 revolutions. The racing crowd so says. Being an old person, I still run the new engine very rich on a test stand a few minutes at time allowing cooling to allow the metal to adjust. After 20-30 minutes it goes on a plane for some rich runs until it is happy.

The big DB engines were held back by several points. They had to use some inferior materials due to shortages. Steels suffered and certain high grade coatings like Stellite were unobtainable. Sparkplugs could only use low Nickel steel, so no precious metal plugs. Large plain bearings could not be made of the best material. Lubricants were limited in performance. There were some structural limitations of DB engines, fuels were problematic.
All in all, the DB engines needed careful running-in, perhaps more-so than Allied engines. IMO, The DB 605 A/B of mid 1943 to mid 1944 was fairly good in the standard rating upto 2800/1.42. However, after that, with poorer production materials and standards, it became very short life at higher ratings with MW50.
In fact, even at standard ratings, the DB 605 had much lower overhaul life than the contemporary versions of RR Merlin.

Eng

 

[Yew Staff]

Some more examples showing the 3min markings for Start&Notleistung:

View: https://www.youtube.com/watch?v=vaeaejnb_GY&embeds_referring_euri=https%3A%2F%2Fforum.il2sturmovik.com%2F&feature=emb_title