In article ,
"Geoffrey Sinclair" writes:
Peter Stickney wrote in message ...

I just double checked, he numbers I gave are a bit muddied-up, too.
I've two Pilot's Handbooks for the Mosquito, one for the FB.6
(Fighter-Bomber) from 1950, and one for the various single-stage
Merlin Night Fighters, published in 1945. The numbers I quoted were
from the FB.6 handbook, and the NF.12 handbook is different. The NF.12
book lists best cruise as 220 mph IAS, which is nudging 330 TAS at
25,000'. and 360 TAS at 30,000'. It's possible that the FB.6 numbers
are for an airplane carrying external bombs and rockets, but it
doesn't say.

Sounds like the time to add the information from the book Mosquito
by Sharpe and Bowyer.

The FB6 used Merlin 21/22/23/25, the NF12 merlin 21/23.

True, but, in the case of long range cruise, irrelevant. The Merlin
XX/20 series were essentially identical in anything other than the
Combat Emergency (5 Minute) Ratings.
Merlin 21 & 23 were rated at 3000RPM/+14 in Low Blower, and
3000RPM/+14 in High Blower, corresponding to Horsepowers and altitudes
of 1460 HP at 6250' and 1435 HP at 11500', repectively. The Merlin 25
was rated for 3000RPM/+18 in both gears, giving 1640HP @ 2000', and
1550HP @ 9500'. Climb Power (2850 RPM/+9) and Continuous Power
(2650RPM/+7) ratings were the same for all angines. Well, with one
variation - Merlin 21s had a Max Lean Mixture power setting of 2650
RPM/+4, and the later engines had a Max Lean rating of 2650R/+7, due
to better carburation. In the case of cruise speeds, the particualr
engine mark is irrelevant. (And as far as the RAF was concerned, the
F.Mk II, NF. Mk XII/XIII, and NF Mk XVII were interchangable.

Appendix 8, performance of the B35 (merlin 114) versus the FB6
(merlin 25).

B35, 22,000 pounds, bomb load 1,500 pounds including 2 x 500
pounds bombs under the wings, 539 gallons of fuel, still air range
1,600 miles at 25,000 feet at 300 mph TAS, 1,250 miles at 37,000
feet at 375 mph TAS. Top speed 425 mph at 30,500 feet.

FB6 21,700 pounds, bomb load 1,500 pounds including 2 x 500
pounds bombs under the wings, 453 gallons of fuel, still air range
1,120 miles at sea level at 250 mph TAS, 960 miles at sea level
at 296 mph TAS. Top speed 378 mph at 13,200 feet.

The Merlin 72/73 or 76/77 versions (VII, IX and XIV) outward
recommended cruising speed 220 mph IAS, economic cruise
in clean condition was 295 mph TAS at 20,000 feet and 350
mph at 30,000+ feet, maximum continuous cruising, clean,
349 mph TAS at 20,000 feet, 378 mph TAS at 30,000 feet.

For the merlin 21/22/23/31 equipped versions maximum
continuous cruise was 341 mph TAS at 20,000 feet but this
fell to 329 mph at 25,000 feet, I assume in clean condition.
Again outward bound recommended cruise was 220 mph
IAS at around 25,000 feet.

The return flight recommendation was for around a 5% reduction
in cruise speed compared with outbound, 210 mph IAS.

As I explained in my other post in this thread tonight, the
differnence in Cruise True Airspeeds is due to the higher critical
altitudes of the two-stage (60, 70, and 100 series) engines. The
Cruise IAS stays the same.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster