Inverted V engine vs. V engine

[B-17engineer]

The only thing I have an issue with is the visibility. When landing the tailwheel is still on the ground (therefore impeded visibility.) and as in the picture I posted the propeller would have been lower in the plane than a regular V engine, could a lower propeller cause an different in the aircraft performance?

 

[Tartle]

Yes the Merlin or PV-12 as it was first called was schemed as an inverted engine in 1933, but when Camm and Mitchell discussed it with Royce they decided to un-invert it. This photo from my collection will show you what the Germans saw... did it give them something to copy? I reckon not as they had already started work on inverted V but it probably gave them confidence to continue and reap some oiling problems!

The Germans had already decided to try for /\ as can be read below (from AEHS author I think..can't find a link)

"The Origin of the Inverted V-12 German Aero engines.

This goes back to 1928 when a committee of aeronautical experts was assembled in Berlin at the bidding of the R.V.M.
Representatives from the Army, the D.V.L. research centre, the Navy (airships were at their peak in 1928 ) and Deutsche Lufthansa were instructed to make an in-depth study of of the international scene regarding aero-engines and then produce specific guide lines for the future development of large air- and liquid-cooled motors.
Along with others, Prof. Wunibald Kamm (of "Kamm Tail" fame), Ing. Wolfram Eisenlohr (famous pilot and head of the D.V.L. power plant division) and Dr. Helmut Sachse (later, co-designer of the B.M.W. 801) served on this panel.
The specifications drawn up by this "think tank" were very detailed and incorporated some very advanced features including, for the liquid -cooled engines:
- 12-cylinder, inverted installation,
- mono-block cylinder banks,
- wet cylinder liners,
- propeller reduction gear,
- supercharger,
- fuel injection,
- high temperature glycol cooling,
- provision of a cannon tunnel in the Vee.

Tender documents were sent to Daimler-Benz, Junkers and B.M.W., all of which eventually produced a V-12 engine model in response although none was able to incorporate all of the required features immediately, eg the DB600 had dry liners and carburettors, the JU210 also had only carburettors and the B.M.W. 116/117 only got as far as the prototype stage.
The specifications were presented to the manufacturers as a fait accompli. If they wanted production orders, the engines had to comply with the tender descriptions.
Wolfram Eisenlohr was interviewed in 1980 re the 1928 requirement for inverted V-12s and he cited three reasons for the decision vis,
- more compact installation,
- better pilot view for single engined aircraft,
- less exhaust flame dazzle during night flying.

Ref: Junkers Flugtriebwerke by Müller, R, p 150 - 151. (Helion and company)
von Gersdorff et al "Die Deutsche Flug..." p 42.
ISBN 1-85260-163-9; Fred Jakobs, Robert Kröschel and Christian Pierer. "BMW aero engines". BMW Group Classic, 2009 ISBN 978-3-86852-214-3. p 85 -87."

A Rolls-Royce engineer was one of a team that went to Germany near the end of WWII. The Report is called, "Comments on Visit to Germany, July 24th 1945 to August 12th 1945".

10 persons made up the visiting party, including P.G.Barlow and E. Wolsey (M.A.P.), Mr A. Thomas (Armstrong Siddeley Motors), Mr N. Quinn (Bristol Aero Co.), Mr R. Chamberlin (D. Napier Son) and Mr G. Morris (Rolls-Royce Ltd).

Page 3 of the Report says, "A good example of Air Ministry control lies in the inverted Daimler-Benz engine. The D.B. people said that both from a technical and production point of view they would have preferred to make an upright engine but they were compelled to make it inverted by the Air Ministry."
The Air Ministry people were in the team that went to R-R Derby in 1933... hence my thought that the mock up had some influence on German choice of /\.

With the inverted engine, they said it was very difficult to obtain consistent oil consumptions and due to the rotation of the crankshaft, one bank gets more oil than the other. For this reason the engine is built with a lower compression ratio on one bank than the other."
The DB 605 compression ratios were, I believe:
Right bank - 7.3 : 1
Left bank - 7.5 : 1

 

[Tartle]

If we look at engine development activity we get a picture like this:
Junkers... in 1933 Junkers started on design and constructionof 2 petrol /\12s which were running by 1936
They were monobloc and hard carburetters...
the model 210 bxs was 124x135 mm = 19.7 litre
the model 211 bxs was 150x165 mm = 35.0 litre

BMW Mark 116 ran in 1932. Also known as BMW XII it was a /\12 with bxs 130.0 mm, 20.6 litre capacity giving 600 hp. abandoned in 1937 for a radial supercharged configuration.

Daimler-Benz carried out many prototype studies before settling on /\12 in 1934. With glycol cooling and carburetters the DB 600 ran in 1935.
Prior to that there was the F4 engine which started in 1929 and the first of two prototypes ran in 1931.. I believe these were to the Ministry spec. These were developed into the F4B which became the prototype DB600...bxs 150x160 with a 33.93 litre capacity... the DB601A-1 was developed from the DB600.
If anyone has better info on this story please share and improve the data I have posted here!

 

[tyrodtom]

While a inverted engine might make it necessary for more steps for oil control in the crankcase, it would make oil control in the valvetrain area simpler, gravity would tend to keep excess oil from pooling around the valve guides, that's a major source of oil lose in regular configured engines.

 

[slaterat]

An inverted engine is going to have issues resulting from the inversion, mainly increased oil consumption. Can they be solved, the answer is an obvious yes. Is it worth the effort, probably not judging by the results. The lighter RR merlin was always able to match the heavier DB. The credentials of the merlin are represented by the success of the aircraft it powered.

Spitfire best interceptor of the war
Mustang best long range fighter of the war
Mosquito best medium bomber of the war
Lanc best heavy bomber of the war (until the B 29)
Hurricane allied fighter credited with more more ea shot down than any other allied aircraft

Slaterat

 

[Readie]

An inverted engine is going to have issues resulting from the inversion, mainly increased oil consumption. Can they be solved, the answer is an obvious yes. Is it worth the effort, probably not judging by the results. The lighter RR merlin was always able to match the heavier DB. The credentials of the merlin are represented by the success of the aircraft it powered.

Spitfire best interceptor of the war
Mustang best long range fighter of the war
Mosquito best medium bomber of the war
Lanc best heavy bomber of the war (until the B 29)
Hurricane allied fighter credited with more more ea shot down than any other allied aircraft

Slaterat

Well said. That is the point I was trying to make to Marcel.
Inversion was a developmental dead end.

Cheers
John

 

[Marcel]

Well said. That is the point I was trying to make to Marcel.
Inversion was a developmental dead end.

Cheers
John

And I was not challenging that statement, but merely your way of argumentation

BTW, slaterat is making that same mistake, using personal views to reason his statement. For example "Spitfire best interceptor of the war" is something that many on the forum would and could challenge. Again, I'm not challenging the statement, but the way it is presented.

 

[Mustang nut]

Well said. That is the point I was trying to make to Marcel.
Inversion was a developmental dead end.

Cheers
John

I think all internal combustion engines were a dead end for military aircraft by 1944. rolls Royce themselves stopped work on internal combustion enignes to concentrate of jets.

 

[wuzak]

Actually jets, or gas turbines, are internal combustion engines.

Steam engines are external combustion engines.


Wonder what had happened if the Metrovicks F1 turboprop had got up an running before or early in the war. As it was they cancelled that to work on the F2 jet.

 

[Tartle]

One of the issues that seemed to crop up on the DB's is that of oil aeration at altitude. This may have been more of a problem as the master conrod bearings went from roller on the 600/601 to plain on 605 to roller on 603A1 to plain on 603A2.... bombing of bearing factories may also have a bearing (excuse pun!). This

shows Merlin development through type tests/ approval tests over the war years. I have put blue triangles on and a red curve which represent max power of DB 600 series. The power increase on DBs seems to come from increasing the rpm and longer valve timings as well as a capacity growth from 33.9 to 44.7 litres. RR developed the Merlin through increasing the charge... power depends on mass flow of air plus fuel (the charge) into engine, so more charge per minute = more power so increased supercharger pressure ratio is good until detonation sets in.. then in the allies case we could switch to higher octane and the cycle of development continues.. but increased pressure also means higher charge temperature, which increases the risk of detonation so then charge cooling needs to be done; all while improving component strength and reliability. I get the feeling that it was a close run thing which engine was in the ascendant but RR had more development freedom both technically and politically plus a well structured development and manufacturing team that could respond to the RAFs needs....(building modified Spitfires etc as needs pressed.... and there was the Griffon lurking to take over when it was deemed necessary. If the Merlin had remained inverted would it have developed as well, given the organisation to support it.. I guess so because not having direct into cylinder injection and mechanical supercharger arranged symmetrically would have allowed the same technical 'tricks' to take place... a great deal of DB's woes came from not looking at the whole powerplant systematically so technical choices constrained them in ways not envisaged in 1927 and 1934.... but it was a close run thing!

 

[Tartle]

Mustang nut... The Westland Wyvern is an aeroplane that had piston and turboprop propulsion so is worth looking at in the context of a step change in internal combustion technology. There may be others.

 

[Mustang nut]

Mustang nut... The Westland Wyvern is an aeroplane that had piston and turboprop propulsion so is worth looking at in the context of a step change in internal combustion technology. There may be others.

There were quite a few including a P51 mustang variant the Piper PA-48 Enforcer.

On the subject of engines being upside down, the fore runner of the Napier Sabre the Dagger was a H format with the cylinders vertical so half of the engine was "upside down"

 

[DonL]

The lighter RR merlin was always able to match the heavier DB.

When was the RR merlin lighter compare to the DB 601/605 series?

AS 100 times discussed both engines had near the same dry weight and near the same weight with superchargers and all peripheral devices.
The RR merlin had less displacement compare to the DB 601/605 but not less weight!

Spitfire best interceptor of the war
Mustang best long range fighter of the war
Mosquito best medium bomber of the war
Lanc best heavy bomber of the war (until the B 29)
Hurricane allied fighter credited with more more ea shot down than any other allied aircraft

Is this you personal subjective opinion and nothing that is based on facts, accept the Mosquito claim.

shows Merlin development through type tests/ approval tests over the war years. I have put blue triangles on and a red curve which represent max power of DB 600 series. The power increase on DBs seems to come from increasing the rpm and longer valve timings as well as a capacity growth from 33.9 to 44.7 litres. RR developed the Merlin through increasing the charge... power depends on mass flow of air plus fuel (the charge) into engine, so more charge per minute = more power so increased supercharger pressure ratio is good until detonation sets in.. then in the allies case we could switch to higher octane and the cycle of development continues.. but increased pressure also means higher charge temperature, which increases the risk of detonation so then charge cooling needs to be done; all while improving component strength and reliability. I get the feeling that it was a close run thing which engine was in the ascendant but RR had more development freedom both technically and politically plus a well structured development and manufacturing team that could respond to the RAFs needs....(building modified Spitfires etc as needs pressed.... and there was the Griffon lurking to take over when it was deemed necessary. If the Merlin had remained inverted would it have developed as well, given the organisation to support it.. I guess so because not having direct into cylinder injection and mechanical supercharger arranged symmetrically would have allowed the same technical 'tricks' to take place... a great deal of DB's woes came from not looking at the whole powerplant systematically so technical choices constrained them in ways not envisaged in 1927 and 1934.... but it was a close run thing!

I think you should compare the RR merlin with the DB 601/605 series, the DB 603 and Jumo 213 are more comparable to the Griffon engine because they were heavier engines. Dry weight (roundabout 900kg).

I agree that it was a close run thing, but at the end of the war with "disparate weapons". As I sad before in this thread, the much better high performance fuel and the availability of special alloys was turning the balance but not technology advantage.

Anyway the whole issue started about this statement

There is a 'right' way to have an engine and a 'wrong' way.
Inversion is the wrong way.

This statement is wrong and ridiculous as the performances of the invert engine had shown the whole war.

This is the same as:

I have never said that DB engines were intrinsically bad, weak or anything else.

This statement suggest, hell yes "they" had engines that flew, but they were miles away from "our" performances, what is also wrong and ridiculous.

 

[tyrodtom]

As I said before MOST civilian inline aircraft engines of the 30's were inverted.

The Alfa Romeo, Argus, Hirth, De Havilland, Ranger, Menasco, Cirrus, and many more all made inverted engines in 4, 6, V12, and maybe even a V8, all inverted. Most of the civilian light aircraft in Europe in the 30's had inverted inlines , it wasn't some uncommon design practice at the time.

For ungeared engines it was the best design. It allowed the best pilot vision, long propellers, with a short landing gear. It also put the parts of the engine needing the most frequent maintenance within easy reach from the ground, valvetrain and spark plugs.

 

[Mustang nut]

The Merlin was only used so widely because many other designs failed. The lancaster was due to use the Vulture or other in a twin engine design.

The Sabre and Typhoon were a problem and so the Spitfire soldiered on with merlins then Griffons.

In 1939/40 I would say the Bf109 had claim to the best engine because it could nose over and dive. A plane is only as good as its engine and the Bf109 was hardly ever completely out performed until the very end of the conflict. Much of the later performance of the Merlin was down to fuel technology not the engine itself.

 

[Readie]

I think all internal combustion engines were a dead end for military aircraft by 1944. rolls Royce themselves stopped work on internal combustion enignes to concentrate of jets.

Yes, MN you are right of course. I was referring to the piston engine era only.
Cheers
John

 

[Readie]

"Spitfire best interceptor of the war" is something that many on the forum would and could challenge. Again, I'm not challenging the statement, but the way it is presented.

I see your point Marcel, but the Spitfire was the best interceptor fighter. Its not bias, just a statement of aviation history fact.
You may be interested in my Spitfire thread which I will start soon

Cheers
John

 

[Shortround6]

In 1939/40 I would say the Bf109 had claim to the best engine because it could nose over and dive. A plane is only as good as its engine and the Bf109 was hardly ever completely out performed until the very end of the conflict. Much of the later performance of the Merlin was down to fuel technology not the engine itself.

So could most American planes, different carburetors. Late war German engines might not be able to run on German 1940-41 fuel either. At least not at the boost levels used at the end of the war.

 

[Readie]

The Merlin was only used so widely because many other designs failed. The lancaster was due to use the Vulture or other in a twin engine design.

The Sabre and Typhoon were a problem and so the Spitfire soldiered on with merlins then Griffons.
s
In 1939/40 I would say the Bf109 had claim to the best engine because it could nose over and dive. A plane is only as good as its engine and the Bf109 was hardly ever completely out performed until the very end of the conflict. Much of the later performance of the Merlin was down to fuel technology not the engine itself.

Cough, splutter WHAT !!! gads man what are you saying, it borders on high treason.
The Merlin was the most....hang on a minute....you are internet fishing

Nearly 'caught me' too
Nice one
Cheers
John

 

[Readie]

When was the RR merlin lighter compare to the DB 601/605 series?

AS 100 times discussed both engines had near the same dry weight and near the same weight with superchargers and all peripheral devices.
The RR merlin had less displacement compare to the DB 601/605 but not less weight!



Is this you personal subjective opinion and nothing that is based on facts, accept the Mosquito claim.



I think you should compare the RR merlin with the DB 601/605 series, the DB 603 and Jumo 213 are more comparable to the Griffon engine because they were heavier engines. Dry weight (roundabout 900kg).

I agree that it was a close run thing, but at the end of the war with "disparate weapons". As I sad before in this thread, the much better high performance fuel and the availability of special alloys was turning the balance but not technology advantage.

Anyway the whole issue started about this statement



This statement is wrong and ridiculous as the performances of the invert engine had shown the whole war.

This is the same as:
This statement suggest, hell yes "they" had engines that flew, but they were miles away from "our" performances, what is also wrong and ridiculous.

Its a blend of personal opinion and facts. The trouble with a product as good as the Merlin that most other aero engines pale into insignificance.

As far as inversion goes, why all the complexity to turn something upside down? It doesn't make any sense unless, DB did it because they could. There are no advantages to inversion and all the successful high speed piston engines were the right way up.

Sorry,old chum but that is the way it is.

Cheers
John