me 109 engine swaps

[mike siggins]

i read in a jhon weal book that they could change the engines i a d or e model in 15 to 30 minutes anyone heard of this

 

[stona]

I've read through a handbook for the Bf 109 E with the DB 601 engine. It outlines the procedure for fitting the engine to the airframe. It is not a particularly difficult procedure on paper,the design is sympathetic to such a procedure. There are however several very precise alignments to be made (with special tools) and an awful lot of connections (fuel,coolant,electrical systems,instruments etc ) to be made. I find it inconceivable that it would be possible to remove and replace an engine in this type in a 15-30 minute time frame,even given an experienced team of technicians to do it.
I don't know where Weal got the figure from and we might always be surprised by the performance of a skilled team but I reckon (it's just my opinion) that it would take considerably longer.
Cheers
Steve

 

[davebender]

Did Luftwaffe use Sd.Kfz.9/1 crane for changing engines in a field environment?

In this picture Sd.Kfz.9/1 crane is being used to change engine in a Panzer III.
Sd. Kfz. 9/1

 

[nuuumannn]

I have to agree with Steve, having undertaken engine changes on (albeit slightly more modern) aeroplanes, I'd say that it'd take about a day's (eight hours?) work for maybe two or three men to remove and replace the engine - at a guesstimate. If you have too many guys, you're just getting in each other's way. Specialised tooling for the job is mandatory and would go with the guys on the ground where ever they went; they'd have a kit of tooling for each major job that needed to be done. Because the Bf 109 was designed for engine changes to be made on its undercarriage and could be done without lifting the tail, it would make the job easier and therefore quicker; I know that with a Spit you have to jack up the tail to a level attitude, you also might need to remove the wings, but not sure on that one. With the '109 I don't think that's necessary. A crane is obviously necessary, something like a tripod crane easily erected in the field would have been the go at front line airfields.

The Germans being as efficient as they are would have made life easier by colour coding fluid lines etc, making the job simpler, but the whole thing is a job that needs to be done carefully and properly and I'm certain that there would be a few 'tricks' that engineers would need to be aware of. The time taken to remove and refit the engine doesn't always take into account functional checks. I don't know whether the Germans would have felt the need to take the thing for a test flight, but usually this isn't necessary for an engine change; the engineers would take the aircraft and run it against the chocks and do cockpit functionals before it was fully serviceable again.

 

[Aozora]

I know that with a Spit you have to jack up the tail to a level attitude, you also might need to remove the wings, but not sure on that one....

Really?

It could be done with the tail jacked up, but it wasn't absolutely necessary...

With the '109 I don't think that's necessary. A crane is obviously necessary, something like a tripod crane easily erected in the field would have been the go at front line airfields.

For the 109 (and, presumably for other aircraft) a tripod was developed and used:

 

[Snautzer01]

The german did not see engine but "powerblocks" complete sets that could replace engines with lightning speed. A days work?? No you slackers! 30 min from landing till take off with engine replaced. 12 min to change engine,
This was in peace time. In war it could have been faster.
From FlightGlobal. English Aeronautical journal 1938

 

[stona]

But the Daimler Benz installation in the Bf 109 is not a power block type of installation,at least not as I understand it and not going by the illustrations in the hand book. The bearers are attached to the engine,but an awful lot of stuff still needs to be attached and connected. I just doubt it could be done in such a short timeframe,but who knows?

The German "power egg" was more applicable to radial engines or units with annular radiators than the sort of installation on the Bf 109.

That's still a pretty neat trick by the Junkers boys though!

Cheers

Steve

 

[mike siggins]

IL TRY TO FIND WHAT BOOK IT WAS IN MAN ID LIKE THAT HALFTRACK IN MY YARD

 

[FLYBOYJ]

OK - guys, 15 minutes when you have everything set up, crane in place, tools out, etc., de-paneled and ready to go. In the real world it doesn't work that way. I'd bet dollars to doughnuts it takes 10 minutes just to get the cowl off!!!!

 

[Denniss]

According to the F-1 to F-4 manual all separating points were color-coded.

 

[nuuumannn]

Yep, I agree Joe; in the real world things don't happen that fast in maintenance.

It could be done with the tail jacked up, but it wasn't absolutely necessary

I didn't say it was absolutely necessary, its not ideal not to. See those two guys at the back of the engine in the first Spit photo, they're going to have to put their weight on the rear of the engine to align it successfully since the tail's down; much harder than if the tail's level. Interesting to note that in the Bf 109 tripod drawings show trestles for raising the tail to a level attitude and trestling the fuse, although the illustration is not exactly true since the Bf 109's undercarriage legs were attached to the fuselage and not the wings. That's one thing you couldn't do in a Spitfire that you could in a Bf 109, remove the wings with the fuselage unsupported by trestles.

The Ju 90 was pretty slick in half an hour, couldn't do that today; wouldn't want to, you get accused of unsafe practise! It'd be interesting if someone could come up with a definitive timeframe for a Bf 109 engine change.

 

[Shortround6]

Just make sure you are comparing apples to apples. Some aircraft with "power eggs" were fitted with special "quick" disconnect fittings for any fluid lines that were not part of the "egg" and probably electrical plugs for the wiring harness at the appropriate "joints". Having to deal with "normal" fittings (even just on fuel lines) and chase several different wiring connections instead of gang plugs could suck a a bit of time.

 

[FLYBOYJ]

Just make sure you are comparing apples to apples. Some aircraft with "power eggs" were fitted with special "quick" disconnect fittings for any fluid lines that were not part of the "egg" and probably electrical plugs for the wiring harness at the appropriate "joints". Having to deal with "normal" fittings (even just on fuel lines) and chase several different wiring connections instead of gang plugs could suck a a bit of time.

Even with a "QEC" you're still looking at some tedious tasks before and after the change that will take more than 15 minutes. Depending on the engine, just draining any oil on the QEC side of the system takes time. And those "Quick Disconnects"? More than likely there's a requirement for safety wire after they're installed.

 

[Shortround6]

Some of the "quick" disconnects were also automatic shut offs. Perhaps like the fittings used on some Hydraulic lines (like Hurst tools) ? A lot like an air hose fitting, you can take them apart under pressure but they don't go back together with pressure in the line (1500psi)

 

[Airframes]

If I can find the right book, I have a description of an engine replacement on the '109. It was, as has been mentioned, a 'power egg' configuration, and mounted or de-mounted complete with engine bearers attached to the engine.
From what I remember of the description, the '15 to 30 minutes' was how long it took to actually lift out the engine, or put it in place, with all other connections un-done. Actual time to complete an engine change, with all connections made, seemed to vary between three and five hours, and by the time all POL etc had been topped up, all connections fully checked and tightened, and the engine ready for test run was nearer six to eight hours, depending on working conditions, and any other issues affecting working time, such as broken connections, misaligned bolts and so on.
Pics below show a selection of sequences, using the engine lifting beam and telescopic tripod winch tower, and also the 'arch' tower normally used on twin-engine types such as the Ju88.

 

[tyrodtom]

Look at pictures of Bf109s with the engine out, but the armament , especially the motorcannon, still attached to the airframe.
The fuselage would have to level, and the engine pulled out level, very carefully, several feet before it will clear those barrels, or all the nose armament would have to be removed first. Most aircraft armament is designed for easy removal, but all this adds up.

There's a video on U-Tube of some people who had tours of the German aviation industry during Lindbergh's trip to Germany, one of them stated he was told the Bf109 engine could be removed in 15 minutes, but I noticed nowhere did he say he saw them do it.

I can see in the pictures, that they've left the cowl guns alone, but that model of 109 evidently has no motorcannon.

 

[FLYBOYJ]

Some of the "quick" disconnects were also automatic shut offs. Perhaps like the fittings used on some Hydraulic lines (like Hurst tools) ? A lot like an air hose fitting, you can take them apart under pressure but they don't go back together with pressure in the line (1500psi)

I really don't believe those were employed during WW2 and if they were (at least in the west) they would have had a safety wire requirement.

 

[Airframes]

Note that the first, second, and fourth pics in my post have the motor cannon in place - the breech assembly can be seen at the rear of the engine, the other shot is of an 'E' model, no engine cannon.

 

[tyrodtom]

How did they remove the motorcannon for normal maintenance ?

 

[Snautzer01]

and from the manual (no time table)