IJN attacks vs defended islands: Ceylon compared to Midway

[thedab]

I take it that the level speed and time to climb,is done with 6655lbs weight,as it give about the same numbers as is on here Hurricane L-2026 Trials Report with 6750lbs weight

when was the Merlin III cleared for 16lbs boost?

 

[RCAFson]

I take it that the level speed and time to climb,is done with 6655lbs weight,as it give about the same numbers as is on here Hurricane L-2026 Trials Report with 6750lbs weight

when was the Merlin III cleared for 16lbs boost?

Time to climb and climb rate is given at maximum weight, while speed is stated for mean weight.

I suspect that clearance for 16lb boost was given in Jan 1942, but in any event it was sometime before 22 April 1942, which is the date on the Sea Hurricane data card

 

[tomo pauk]

If I may return on the 'no looking for footnotes when reading this or that author'.
First, the excerpts from the W. Bodies book on the P-47. Great book as it was, it is harshly wrongly opinionated on some aircraft:

The wing profile and thickness of the P-38 were certainly both 'slower' and thinner; the Tempest II was outfitted with drop tanks. We cannot speak of duplicating the wing from the P-47N for the Tempest. The P-47 with a 20mm cannon was nothing more than an one-off, and 4 Hispanos were at least a bit more devastating than 8 BMGs, not that it mattered though.

The book by Richard B. Davis, 'Bombing the Axis powers', would lead us to believe that P-38 and P-47 received an extra fuselage tank each. Not the case for the P-38 (it did receive 2 x 55 US gal tanks in wing), nor for the P-47 - the main fuselage tank 'grew' higher, hence it carried 270 instead of 205 US gals.

Next - the widely acclaimed (also from me) book 'America's hunderd thousand' states that P-47M was outfitted by belly rack only, with 110 US gals of external fuel as maximum. There is enough of photos in the 'net showing the P-47Ms carry also wing-mounted drop tanks, eg. here. That should not be a great surprise, the P-47D-30 was the 'donor' of the wing for the P-47M, and that wing was plumbed for drop tanks.

 

[Greyman]

when was the Merlin III cleared for 16lbs boost?

The earliest I have is an amendment to the Hurricane I Pilot's Notes - dated May 1941:

23. NOTES ON THE SEA HURRICANE
(i) Increased boost:
(i) The use of +16 lb/sq.in boost is permitted for periods of about 15 minutes at low altitudes ...

 

[thedab]

good god for 15 minutes?

 

[FLYBOYJ]

good god for 15 minutes?

For some aircraft it's even less.

 

[thedab]

well that what i maen,on the Merlin 45 it just 5 minutes
it's seems too good to be true

 

[Shortround6]

Couple of things may be going in here ( or I have my head planted where the does not shine).

Merlin III used an 8.588 supercharger gear and the Melrin 45 (and XII) used a 9.089 supercharger gear. The 8.58 gears need just under 90% of the power of the 9.089 gears to turn. A slightly lower strain on the engine? The intake charge is heated less. ALso a slightly lower strain on the engine?

Merlin IIIs in Sea Hurricanes might have been considered throw away engines? In the Spring of 1941 the "Sea Hurricane MK I" was starting to operated from CAM ships and any "combat" mission was a one way trip for the airframe and engine. July saw the First deployment on a carrier where the plane might land after combat.

Sea Hurricanes not expected to have to fight a number of days in row using combat power unlike land based aircraft? Carrier only stayed in combat "area" for a few days before withdrawing so engines didn't rack up high numbers of hours at "combat" settings before maintenance periods?

Feel free to shoot holes in any/all theories.

 

[Greyman]

I think the standard '5 minute' emergency boost limit indicated in manuals is quite conservative. I've read several accounts of pilots pulling emergency boost right at - or soon after - take off and keeping it on for essentially an entire sortie.

Possible for a pilot or engine to pull off regularly? Certainly.

Advisable from a logistic/strategic point of view? Most likely not.

 

[thedab]

any know when the Merlin XX was cleared for 16lb boost?

 

[tomo pauk]

Looks like November 1942 (in 2nd supercharger gear only): link

 

[thedab]

So a Sea Hurricane running 16lb boost, anyone know what it's climb and level speed performance would be up to about 10.000ft ?

 

[Shortround6]

Well, at 9,000ft it would be back to 12lbs of boost and at 7250ft about 14lbs boost if you are referring to the early Sea Hurricanes.

 

[Neil Stirling]

Sea Hurricane +16lbs bottom r/h corner.

Neil.

 

[Koopernic]

If I may return on the 'no looking for footnotes when reading this or that author'.
First, the excerpts from the W. Bodies book on the P-47. Great book as it was, it is harshly wrongly opinionated on some aircraft:



The wing profile and thickness of the P-38 were certainly both 'slower' and thinner; the Tempest II was outfitted with drop tanks. We cannot speak of duplicating the wing from the P-47N for the Tempest. The P-47 with a 20mm cannon was nothing more than an one-off, and 4 Hispanos were at least a bit more devastating than 8 BMGs, not that it mattered though.

He makes the tiresome mistake, unforgivable really for an author, of failing to nominate or consider the altitude a fighter achieved a particular speed at. That mistake then endlessly repeats as the author is requoted and another generation begins to make the same mistake again.

I attribute the work of online simulation gamers who had a thirst for data so as to model their simulations.

It's likewise with declarations of range with no indication of load carried and cruise speed chosen and furthermore declarations of performance of an aircraft type with no indication of when it first entered service and for what period.

 

[thedab]

thanks Neil.I didn't see that first time

has any one got rate of climb for any mark of Hurricane on combat power?

 

[Greyman]

Only one I can find:

Hurricane V (Merlin 27) 8,170 lb - 40-mm Vickers Guns
Ground Level: 3,880 ft/min --- +18 boost

 

[thedab]

any one know were I can Pilot's notes for the Sea Hurricane mkI