Spit Mk1 Boost?

[TomcatViP]

One Question Banks : when do you actually get max boost with a supercharged engine ?

And by the way if you were not charging us every three month on the same subject and with the same arguments I would hve been pleased to check out any abbreviations out of my phrases.

As I hve alrdy said, in the RR test manual the latter merlin is rated at 9lb of boost at 15kft not 12 or ...17

By the way I think I am qualified to deal with that subject - just went to check my diplomas just in case

[41Sqn_Banks]

Originally Posted by TomcatViP

One Question Banks : when do you actually get max boost with a supercharged engine ?

I suspect this is a hypothetical question: Highest boost possible boost is at lowest possible altitude at highest possible engine rpm with throttle valve fully open.

Highest allowed boost is available at with highest allowed engine rpm at all altitudes below full throttle height.

But really it's not about getting a high boost at low altitudes but make the engine survive the high boost. No one is telling that +17 boost didn't kill the engine.

As I hve alrdy said, in the RR test manual the latter merlin is rated at 9lb of boost at 15kft not 12 or ...17

So what is your point? There is a difference between "maximum-possible-boost-produced-by-the-supercharger-at-sea-level-that-the-engine-can't-handle-at-all" (around +17), "maximum-allowed-boost-in-case-of-emergency-for-no-longer-than-5-minutes" (+12 for 100octane fuel, +6 1/4 for 87octane fuel), "maximum-allowed-boost-for-no-longer-than-30 minutes" and "maximum-boost-for-infinite-time-...-well-not-infinite-as-your-engine-will-die-even-with-that-boost-after-200hrs-running-without-inspection"

There is no difficulty in getting a high boost at low altitudes from a supercharged engine. The difficulty are:
- Find the highest boost that does only acceptable "damage" to the engine and find ways to reduce the "damage" even further to permit (=allow) the use of higher boosts
- Find ways to maintain the high boost at high altitudes

[Osprey]

Originally Posted by TomcatViP

And by the way if you were not charging us every three month on the same subject and with the same arguments I would hve been pleased to check out any abbreviations out of my phrases.

But he's not giving you an argument. He's giving you a documented fact from Rolls Royce and the RAF. If you don't believe this to be true then I would suggest you provide the evidence, though I suspect you've been asked in the past and haven't managed to. My questioning was around understanding this evidence because I have seen this data in the past and never understood what it actually meant. I want to operate the engine properly and I am grateful to Wedge and Banks for the explanation, now I understand what the cutout actually does.

PS. A personal diploma isn't evidence btw, it just says you went to a college and passed some tests. Congratulations.

[TomcatViP]

Originally Posted by Osprey

PS. A personal diploma isn't evidence btw, it just says you went to a college and passed some tests. Congratulations.

So you throw the insults. I respond politely to calm you down and then you add another layer of xxxxxxxx ?

Where is your mum that I made an urgent request for some (boosted) slap on your pinky butt ? That also I hev done and was rather good

Just to remind you after reading BlkDg post : btw 1940 and 1944 there was Four (4) years of harsh technological development. If they had such boosted Merlin, the MkII would hve been called a MkIX etc.. etc..

WHen dealing with history You need to put things in perspective or you end with acrobatic assumptions such as where we are now.

When dealing with a fleet of airplane at war you need to understand taht factory made does not mean fleet wide or you'll end to say that the F35 is actually in full service just because a couple have just been delivered to an instructor unit (both wings are still on guys ) .

And by the way I did alrdy put RR data on the forum. It does not say 17lb at all : 9 lb max op boost at rated alt. And it was in late 1940 early 41 (cant remember).

I would come back latter for the max boost and alt question but I think I (we) hve alrdy discuss this one alrdy. Just remind that that the boost (the supercharger) was not there for max low speed but for increasing the climb rate and maximizing the overall speed at alt. As I hve alrdy said this is not a car tuning. You don't plug the biggest supercharger to get the max peak power.

~S

PS: the FM of the spit is more of a concern for me
PSS : I am (wwe are) not historian(s). Instead of recreating evidences we shld stick to what are the data in the literature. There is enough to discuss on how any data cld impact the FM. Valec as alrdy post a realy good link to source out any perfs

Originally Posted by Valec

http://www.airpages.ru/eng/uk/spitf1.shtml http://www.airpages.ru/eng/lw/bf109e1.shtml

[Robo.]

Originally Posted by TomcatViP

And by the way I did alrdy put RR data on the forum. It does not say 17lb at all : 9 lb max op boost at rated alt. And it was in late 1940 early 41 (cant remember).

TomcatViP, you seem to be wrong - Merlin III in question was rated +6.25PSI and +12PSI with BCC-O and 100 octane fuel before the BoB actually started (10.7.1940), there many are official documents and with this topic being well documented, there is not much space for arguing or guessing I am afraid.

I really recommend reading any good book about this topic, ''Merlin in prespective'' is pretty much comprehensive and sheds a lot of light on how RR approached aircraft engines in that era compared to say DB - awesome reading.

The +17PSI is not mentioned in any Spitfire book, this is simply a figure the Merlin III achieved (not safely mind you!) without limiting the boost to certain PSI considered as safe and giving the engine reasonable life. That PSI is called 'rated boost' and it was +6.25PSI for Merlin III until they rated it for +12PSI with better fuel. The +12PSI was not standard rating, but highest permissable for short periods of time. Simple as that.

If you have any information about Merlin III being rated at +9PSI max, please provide, I quite like reading about engines.

[Ze-Jamz]

Originally Posted by TomcatViP

Where is your mum that I made an urgent request for some (boosted) slap on your pinky butt ?

Brilliant..

[Osprey]

Originally Posted by TomcatViP

So you throw the insults. I respond politely to calm you down and then you add another layer of bullshit ?

Where is your mum that I made an urgent request for some (boosted) slap on your pinky butt ? That also I hev done and was rather good

Just to remind you after reading BlkDg post : btw 1940 and 1944 there was Four (4) years of harsh technological development. If they had such boosted Merlin, the MkII would hve been called a MkIX etc.. etc..

WHen dealing with history You need to put things in perspective or you end with acrobatic assumptions such as where we are now.

When dealing with a fleet of airplane at war you need to understand taht factory made does not mean fleet wide or you'll end to say that the F35 is actually in full service just because a couple have just been delivered to an instructor unit (both wings are still on guys ) .

And by the way I did alrdy put RR data on the forum. It does not say 17lb at all : 9 lb max op boost at rated alt. And it was in late 1940 early 41 (cant remember).

I would come back latter for the max boost and alt question but I think I (we) hve alrdy discuss this one alrdy. Just remind that that the boost (the supercharger) was not there for max low speed but for increasing the climb rate and maximizing the overall speed at alt. As I hve alrdy said this is not a car tuning. You don't plug the biggest supercharger to get the max peak power.

~S

PS: the FM of the spit is more of a concern for me
PSS : I am (wwe are) not historian(s). Instead of recreating evidences we shld stick to what are the data in the literature. There is enough to discuss on how any data cld impact the FM. Valec as alrdy post a realy good link to source out any perfs

This is really nothing short of an offensive and obtuse post. I am afraid I had to report it.

[Crumpp]

Since Sea Hurricanes were in service in Feb 1941, then the +16lb boost Merlins were available in 1940 since it took, according to you, ~6 months.

Interesting. You are the first source I have seen that makes that claim. Most agree that the prototype Sea Hurricane was flying by Feb 1941.

Most other sources agree that it was not until ~July 1941 that it became operational.

Once the Fleet Air Arm took delivery of the Hurricanes from the RAF, starting with 880 squadron in March 1941 and 804 squadron in April 1941 it then started the mamoth task of shipping the Hurricanes to operational squadrons in all theatres around the world. A large consignment was shipped out in HMS Furious to 807 squadron in Gibraltar on 1 July 1941 (eg V7301 and V7623). Whilst others were shipped to South Africa in SS City of Bombay on 9 January 1942 (eg Z4056). Half a year later further consignments were shipped out on SS Belgian Seaman to Takoradi from Liverpool on 30 June 1942 (eg BP709), and to Simonstown in SS Lt St Lonbert Brie thence to 800 sqn on HMS Indomitable in July 1942 (eg V7416). However, quite a number were lost with the HMS Eagle which sank on 11 August 1942.

http://www.fleetairarmarchive.net/ai.../hurricane.htm

Sounds kind of like EXACTLY what I told you is typical....

[Seadog]

The first carrier borne Sea Hurricane kill was recorded on July 31 1941, by Sea Hurricanes operating from HMS Furious. The type must have been operational some months sooner with development occurring from mid to late 1940 to early 1941. However, this does not mean that all Sea Hurricanes used 16lb boost right from the beginning. I suspect that the 16lb boost mod was not made until late 1941/early 1942. Brown, in Wings of the Navy, mentions that it was used for the Sea Hurricane IC which had the Hurricane IIC, 4 x 20mm cannon wing, grafted onto a Sea Hurricane IB airframe.

[Al Schlageter]

The squadron formed at Arbroath in January 1941 as a Fleet Fighter squadron with 3 Martlet Is, intended for the still uncompleted HMS Indomitable. The squadron was augmented with 3 Sea Gladiators and 9 Sea Hurricane IAs untill replaced with Sea Hurricane Ibs in July 1941.

The first Sea Hurricanes joined No 880 squadron at Arbroath, Scotland, in January 1941. In July 1941, they joined their aircraft carrier, ‘HMS Furious’.