Engine choices for P-51 mustang ?

[ThomasP]

Also, there are several correct spellings for the mythical creature - ie Griffon, Griffin, and Gryphon in the English usage. In Turkish and Spanish it is spelled Grifon, in French it is Griffon, and in Italian it is Grifone.

 

[MiTasol]

The V-1710's air intake was above the nose as it had a downdraft carburettor.

The Merlin versions needed an intake below the nose because the Merlin had an updraft carburettor.

Doesn't sound like "the designers thought right from day one of the Merlin conversion".

And if Rolls-Royce hadn't come up with the 2 stage engine, the P-51 may never have been converted.

I did not discuss the Allison versions as my post was only in relation to the Merlin variants.

The very first NAA designed Merlin powered Mustangs had all these features I listed and given the speed that the redesign was carried out and put into production those features must have been part of the design teams requirements from the start.

Furthermore all those elements were in the Allison powered Mustangs with two variations. The screen was further forward so it could catch any large items except material from filter failures and there was no emergency air door although the hot air door would supply more than enough air to keep the engine running at fairly high power levels. You will note that icing conditions were also automatically corrected for on the Allison engine versions as well as the Merlin powered versions. I had neglected to mention that earlier.

and later version of same

You are probably right about the 2 stage engine and we have a top expert on the subject in the forum who has yet to weigh in.

 

[Engineman]

The Rolls-Royce production piston aero-engines of the period were named after Birds of prey.
EAGLE
HAWK
FALCON
CONDOR
KESTREL
BUZZARD
GOSHAWK
PEREGRINE
VULTURE
MERLIN
GRIFFON
EAGLE H24

There were few exceptions once the name was officially applied by RR. However, there were also RR abbreviated codes for engine types Such as the type F (Falcon), the early Kestrel (F.X), the Eagle XVI (not produced), the type H (Buzzard) and the PV 12 (Merlin).
There was also the "Racing H" development of the Buzzard, which was differently named as the "R-Type". After development, the aero versions were effectively 1929 version and 1931 version.
Rolls-Royce also used technical abbreviations for the later engines, eg RM.10SM which was the Merlin 65/66/67.

Eng

 

[MiTasol]

Though there were also a series of RR piston engines named after rivers like the Exe and Pennine?. I do not think any of those actually went into production and I think all were best forgotten.

 

[pbehn]

Because the 37 litre V12 engine which actually flew in WW2 was derived from a much earlier design of the same bore and stroke which lay dormant at RR dating from just after the Schneider Trophy days, which WAS called "Griffin"

The two names were often mixed up ever-after.

View attachment 745295

They are permanently mixed up, Griffon and Griffin as well as Gryphon are all names for the same mythical beast with the legs body and tail of a lion and the wings and head of an eagle.

 

[Engineman]

Though there were also a series of RR piston engines named after rivers like the Exe and Pennine?. I do not think any of those actually went into production and I think all were best forgotten.

Hi,
Also, the Crecy. I am not aware what happened to the Birds of Prey names there, although I think those were all experimental projects, rather than production prototypes, although the Exe did reach the stage of a technical designation RB.1SM. The RB was for Rolls Boreas, but they had to drop that as it clashed with Bristol names.
River names were widely adopted for Gas Turbine engines, representing "rivers of power".
BTW, a like tick awarded for the possible reason of the "R-type" name, other than "Racing", or "Rolls", or "Royce" ?

Eng

 

[Engineman]

They are permanently mixed up, Griffon and Griffin as well as Gryphon are all names for the same mythical beast with the legs body and tail of a lion and the wings and head of an eagle.

Yes, but the Griffon name here was the particular Bird of Prey, Griffon-a type of Vulture.

Eng

 

[drgondog]

When we designed the mustang was there a better choice than a V-1710 ? I'm talking P-51A and A-36 time period what were the options was Naiper still making their 24 cylinder H-patteren engine ? I'm not an allison guy so thats why im asking did we have better options ?

Allison was a sister company owned by General Motors. NAA was thinking Allison even before the V-1710 was ever flight tested - all the way back to XC-602 RFP for two seat Pursuit in 1935. Lee Atwood designed the P-198 in anticipation of competeing but the RFP was pulled by Materiel Division.

In 1940 only R-R and Allison had good in-line engine (not incl DB601 for obvious reasons). Kindelberger contacted R-R USA in May 1941 and R-R sent design packages and details for P-40F and Beaufighter installations but GM Board shut the discussions down.

The issues for alternatives (incl Griffon) were weight primarily but also envelope size of the engine. In the case of Allison w/2nd stage auxiliary, it was length.

All the options except Merlin would require major redesign to move wing forward.

 

[drgondog]

To the questions regarding 'chin' vs 'other' carb intake design.

There was another variation on location and configuration explored for better aerdynamics on the XP-51B. Visualize the lower cowl line of the XP-51J

The carb updraft inlet was located beneath the carb inlet of the engine, oval in shape and flush with the lines of the cowl. I don't have the documents discussing the design but it seems obvious that whatever slight improvement of parasite drag (form) of CDp=0.0004 (comparable to gun ports on P-51D) that the obvious 'potential FOD vacuum cleaner effect' of that location was not a better idea.

 

[special ed]

What are the underwing intakes shown in that picture?

 

[wuzak]

To the questions regarding 'chin' vs 'other' carb intake design.

There was another variation on location and configuration explored for better aerdynamics on the XP-51B. Visualize the lower cowl line of the XP-51J

The carb updraft inlet was located beneath the carb inlet of the engine, oval in shape and flush with the lines of the cowl. I don't have the documents discussing the design but it seems obvious that whatever slight improvement of parasite drag (form) of CDp=0.0004 (comparable to gun ports on P-51D) that the obvious 'potential FOD vacuum cleaner effect' of that location was not a better idea.

Not to mention a lack of ram air.

 

[wuzak]

I did not discuss the Allison versions as my post was only in relation to the Merlin variants.

My apologies.

I misread what you had written, thinking that you were saying NAA were thinking of the Merlin conversion while designing the P-51 prototype.

 

[wuzak]

Though there were also a series of RR piston engines named after rivers like the Exe and Pennine?. I do not think any of those actually went into production and I think all were best forgotten.

The Exe was named for a river, while the Pennine was named for a mountain range.

A development of the Pennine was to be called the Snowdon.

So maybe air-cooled military engines were to be named for rivers, air-cooled engines for civilian use for British mountains?

The Crecy, a 2-stroke, was named after an historic battle.

Liquid-cooled 4-strokes were named after birds of prey.

 

[Engineman]

The Exe was named for a river, while the Pennine was named for a mountain range.

A development of the Pennine was to be called the Snowdon.

So maybe air-cooled military engines were to be named for rivers, air-cooled engines for civilian use for British mountains?

The Crecy, a 2-stroke, was named after an historic battle.

Liquid-cooled 4-strokes were named after birds of prey.

Well, the Exe was a play on words as an X-24 aircooled Sleeve valve configuration EXperimental engine. The Pennine was a larger development of the Exe, testbed run.
No-one got a guess about the name of the tremendously important "R"-type?
Eng

 

[EwenS]

The Exe was named for a river, while the Pennine was named for a mountain range.

A development of the Pennine was to be called the Snowdon.

So maybe air-cooled military engines were to be named for rivers, air-cooled engines for civilian use for British mountains?

The Crecy, a 2-stroke, was named after an historic battle.

Liquid-cooled 4-strokes were named after birds of prey.

The Exe began as the "Boreas" after the Greek God of the cold north wind, storms and winter. According to Lumsden "British Piston Aero-Engines and their Aircraft" the name was changed "because it infringed Bristol's Greek mythology names".

 

[Engineman]

Yes, see my reply #206 above.

Eng

 

[BiffF15]

What are the underwing intakes shown in that picture?

I believe those are the gear wells with inboard gear doors in the up position (versus the droop).

 

[MiTasol]

To the questions regarding 'chin' vs 'other' carb intake design.

There was another variation on location and configuration explored for better aerodynamics on the XP-51B. Visualize the lower cowl line of the XP-51J

The carb updraft inlet was located beneath the carb inlet of the engine, oval in shape and flush with the lines of the cowl. I don't have the documents discussing the design but it seems obvious that whatever slight improvement of parasite drag (form) of CDp=0.0004 (comparable to gun ports on P-51D) that the obvious 'potential FOD vacuum cleaner effect' of that location was not a better idea.

Most interesting. Given that NAA were heavily into keeping FOD out of the engine and had filters etc in all the other variants (and designs) I would expect this variant to also have them but I cannot envisage where they would have located them.

Is there any other information publicly available on this variant?

 

[drgondog]

Most interesting. Given that NAA were heavily into keeping FOD out of the engine and had filters etc in all the other variants (and designs) I would expect this variant to also have them but I cannot envisage where they would have located them.

Is there any other information publicly available on this variant?

It wasn't a variant per se. A short lived modification that was restored to 'original' before turing over to Wright Field in May 1943. I don't know whether it was 352 or 421, but suspect 352 (#1 XP-51B) while #2 at Ames solving the Rumble issue. As I think I said, I don't have drawings or correspondence on this one.

Not so on the variants; The P-51B-1 did not have the carb fiter, although it may have been installed later after the P-51B-5 was introduced

 

[Reluctant Poster]

It was far more reliable than the Merlin at all stages of the war,

.It was far more reliable than the Merlin at all stages of the war,

Do you have any evidence to support that