Daimler-Benz DB 605 Oil System...I Don't Understand

[stona]

The inversion was one of the primary requirements for reasons remembered by Eisenlohr and noted in my post #9 above. The tunnel was also a requirement, but nobody has suggested that this was dependent on the inversion and Eisenlohr did not note it as a reason for the inversion.It just so happens that the inverted arrangement and the tunnel were part of the same set of specifications.
Cheers
Steve

 

[Guv]

Well weapon packaging must have been of some concern. How many non-combat aircraft have use the inverted Vee configuration? Did the Merlin powered HA-1112 still have cowl guns? It didn't have the hub cannon.

 

[MiTasol]

My engines instructor at A&P school ...., and he said the heavies were flying longer missions than the engine designers ever envisioned, and the engine oil tanks weren't big enough for the consumption they were experiencing.
Cheers,
Wes

In the early 70's the late Jim Maloney often said of the Planes of Fame B-17 that on cross country flights they would pull into airports mid-route and tell the FBO to dip the fuel and fill the oil. He also said if the aircraft went down you would be able to follow it direct from the last take-off point by following the oil slick the Wright Oilcones left

 

[XBe02Drvr]

Wright engines always seemed to be leakers. (Maybe they hired Brits to design their gaskets?) We had 1820s and 3350s on various Navy aircraft, and later my Beech freighter shared a tarmac with a nicely restored B-25 whose 2600s kept the asphalt well lubricated. Not only do they leak, but Wrights seem to shake, rattle, clatter, and idle rough compared to Pratts, and an S-2 at takeoff power feels like it's shaking itself to pieces. (Not that I'm prejudiced or anything!) Our cowboy local cropdusters used to land their Pratt powered Ag-cats and Stearmans in the grass next to the runway, set the brake, hop out and go take a whiz in the bushes while the 985 sat there quietly ticking over. (Persona Non Grata in the terminal building, and they knew it!)
Cheers,
Wes

 

[elbmc1969]

I would even dispute that, since the system would have worked if the engine was inverted or upright.

The main differences between the DBs and the Merlin and V-1710 were the placement (and size) of the supercharger and the intake manifolding.

These are what make the hub gun possible, not the inverted layout.

I would have though the inverted V was in order to gain better view for the pilot, especially downwards at the front.

The French put the hub-mounted HS-7/HS-9 in service in 1933 in the Dewoitine D.501. The same basic engine and gun setup was used in the M.S.406, which was later upgraded to the HS-404. The D.501's armament was terrifying in 1933, and even in 1936: who else had cannon-armed fighters in wide service? It was definitely the best available bomber-killer in its prime.

The weakness of the HS-9 and HS-404 was their use of ammunition drums instead of belts. This limited cannon ammunition and made it impossible to mount MGs in the cowling because he drum stuck up above the barrel and ate up space inefficiently.

With the hub-mounted HS-404, the M.S.406's effective anti-fighter firepower was approximately equal to the the Bf109E-3 with its paired, but wing-mounted, MG-FFs. Remember, this is before the introduction of the Minengeshoss. The higher muzzle velocity of the HS-404 probably made the M.S.406 slightly better against other fighters, while the slightly greater rate of fire of the harmonized MG-FFs probably made them marginally better against bombers. Not too much to choose between them.

Sorry for going off-topic.

 

[swampyankee]

Inverted engines were pretty common between the wars, being made in Germany, France, the United Kingdom, the United States, Czechoslovakia, Italy, and likely elsewhere. Most were ungeared, and used the inverted layout to raise the thrust line.

 

[MiTasol]

Big difference! Air cooled engines (such as radials) must operate at a wide range of cylinder temperatures, thus requiring looser tolerances in pistons and rings, which increases oil consumption significantly. Liquid cooled engines, on the other hand are able to keep their cylinder temperatures pretty constant, allowing tighter tolerances, more efficiency, and reduced oil consumption.
Cheers,
Wes

And on radials the clearance between the valve stem and guide allows a lot of oil to leak from the rocker hats into the induction and exhaust systems. This is one of the reasons for pulling through and checking for hydraulic lock before starting.

 

[XBe02Drvr]

And on radials the clearance between the valve stem and guide allows a lot of oil to leak from the rocker hats into the induction and exhaust systems. This is one of the reasons for pulling through and checking for hydraulic lock before starting.

It's all about the w I d e temperature range they have to operate under.

 

[Dash119]

It also seems like maintenance in the field might be easier. The inverted vee puts the "top end" of the engine on the bottom and thus is easier to reach from the ground.

 

[gumbyk]

It also seems like maintenance in the field might be easier. The inverted vee puts the "top end" of the engine on the bottom and thus is easier to reach from the ground.

right up until you're putting it back together and drop the washer... Putting the top end back together with gravity working against you is a job best left to someone else.

 

[Shortround6]

right up until you're putting it back together and drop the washer... Putting the top end back together with gravity working against you is a job best left to someone else.

Well, at least you won't have to stand on a ladder to do it
and dropping a washer when your standing on a ladder is a real pain in the ass.

 

[Dash119]

While I would agree that assembling the entire top end would be problematic, it seems like simpler maintenance might be easier. You're not going to drop anything down into port or simply down into the cowling. Additionally, if you had to pull the heads on a Merlin or an Allison wouldn't you pull the whole motor? Rebuilding the top end on a Merlin while it sits in the airframe doesn't strike me as a great way to spend the day.

 

[Shortround6]

The most frequent job is going to be changing spark plugs.

 

[GrauGeist]

...and dropping a washer when your standing on a ladder is a real pain in the ass.

So is dropping the 3/8 (or 10mm) socket.

At least with an inverted engine, the socket won't sound like a pachinko ball as it goes down under the engine and subframe on it's way to the exact center of the vehicle...

 

[MiTasol]

So is dropping the 3/8 (or 10mm) socket.

At least with an inverted engine, the socket won't sound like a pachinko ball as it goes down under the engine and subframe on it's way to the exact center of the vehicle...

especially when that socket or 3/8 or 7/16 nut drops into a spark plug hole. @!#$%^&*(

 

[gumbyk]

Having worked on an inverted in-line engine, and a horizontally opposed engine, I know which one is easier.
An inverted engine inevitably is at just the wrong height - too low to stand up, and too high to sit at.

Regarding removal of the head of a V-12 to work on it, it's done reasonably regularly, and is easier than having to remove the whole engine, and then removing the head.

 

[MiTasol]

And trying to wrestle a DB60n bank on while it is trying to drop off would be a tad difficult I suspect.

 

[GrauGeist]

I beleive I've seen a photo somewhere of a Bf110 being worked on, where the head was being lifted into place by a mobile jack, much like how an automotive transmission jack is designed.

 

[XBe02Drvr]

Regarding removal of the head of a V-12 to work on it, it's done reasonably regularly, and is easier than having to remove the whole

As long as you don't drop a socket into one of the coolant passages!

 

[GrauGeist]

At least dropping a nut (or socket) into a cylinder can be fixed by using one of those remote magnet thingies (<- professional term), if it goes goes into the water jacket or down through a sump hole into the oil pan, it's game over...