WI: Gloster F.9/37 with Merlins from day one

From other thread:

The 360 mph figure for the Gloster is suspicious IMO. The aircraft was the size of Me-210, with far less exhaust thrust and outfitted with radial engines (= more drag than half-decent V-12 installation)....

Err, no - Me-210 weighed in at (A-1) 17,857 lb, Span 53' 7.25", Length 40' 3", W/area 389.654 sq. ft.

Gloster F.9/37 Weights: empty 8,828 lb., loaded 11,615 lb., span 50', length 37', wing area 386 sq. ft.

So the only thing comparable is the wing area, the big difference is the weight (the A-2 version was another 7,500 lb. more).

As for the Gloster's speed - 360 mph was not an estimate - it happened first flew in April '39.

Thanks for the effort to post the particularities.
Yet - the weight have had next to nothing to do with speed between sea level and critical altitude, unlike the drag. Drag is related to drag coefficient, and size of aircraft, especially the area of the wing. The Me 210 have had less powerplant-related drag, more exhaust thrust, much more engine power, yet it was still doing only 350 mph with DB 601F engines. Or, 330 mph, if we go by German wikipedia article.
So I'll reiterate that 360 mph speed figure for any historical F.9/37 is to be taken with a large grain of salt.
Now, a hypothetical variant with Merlins...
 
According to BSP - the Merlin equipped Reaper - with the same wing dimensions - had an estimated speed of 390 mph.

But if with the lower rated Taurus the Gloster reached 330 mph confiming that speed with the Peregrines in place, then the higher speed doesn't seem that out of place.
And the Me-210 Wm Green (though some people have differing views about his sources) quotes - 385 mph.

The other one to compare is the Fw-187 w/span, length, & weight are very similar - with two in-line 700 h. p. engines its max is 326 mph.
 
So I'll reiterate that 360 mph speed figure for any historical F.9/37 is to be taken with a large grain of salt.

I just want to iterate that I am quite willing to take the 360 mph figure salt-free, being borderline hypertensive. The lower rated Taurus actually returned 332 mph, and the Kestrel-Gloster, which had a revised and smaller wing, registered 330 mph. Estimated and expected speeds don't mean much, and you can quibble about the degrees to which aircraft were equipped with combat gear, but Boscombe Down test numbers have always seemed honest to me. If you wish to present sufficient data to re-affirm your belief in the disparity, such as documented frontal area and drag coefficients, feel free. I have only done such comparisons between British twins, and between German twins.
 
It would be useful that we know what Me 210 Green mentioned, as well as what Merlins are assumed on the Reaper.

The Me 210C (=DB 605A on board), again according to German wikipedia, was good for 580 km/h (~360 mph). The Me 410 (DB 603A, some 300 HP more than 605A, granted it was a heavyweight) - 388 mph. Both aircraft have the advantage of maxing out the speed at around 22000 ft, the Gloster (whether with Peregrines or with fully-supercharged Taurus) at around 16000 ft, where the air is thicker.

Engine powers at 5.7 km (~18500 ft; ballpark for rated/critical altitudes for all of the listed engines, bar 601E), no ram effect, no exhaust thrust, approx. in HP:
Merlin 45 - 1150
Merlin 20 series - 1110
DB 601E/F -1180
DB 605A, fully rated - 1300; restricted (mid 1942 to late 1943) - 1240
Db 603A - 1600

All engines will of course do more/much more power under that altitude. Ram effect will mean the aircraft's rated/critical altitude is higher than of the 'static' engine, up to several thousand feet.
 
I just want to iterate that I am quite willing to take the 360 mph figure salt-free, being borderline hypertensive. The lower rated Taurus actually returned 332 mph, and the Kestrel-Gloster, which had a revised and smaller wing, registered 330 mph. Estimated and expected speeds don't mean much, and you can quibble about the degrees to which aircraft were equipped with combat gear, but Boscombe Down test numbers have always seemed honest to me. If you wish to present sufficient data to re-affirm your belief in the disparity, such as documented frontal area and drag coefficients, feel free. I have only done such comparisons between British twins, and between German twins.

Hopefully some questions can be answered, that are not quibble:
Was the 360 mph attained during the 1st flight, or it was acieved in Boscombe Down? Do we know the date of the test in B.D? Condition of the aircraft during the tests (armament installed or not, what armament, plane painted or not, radio mast & antennae present, ballasted for ammo or not, ditto for radio)? Rated altitude for Taurus engines used?

I'm of course interested in details of the wing of 'Peregrine Gloster', as well as with your comparisons between the comparable aircraft.
 
This is a comparison. One is bigger and heavier and has a radiator and a pair of cannons sticking out the back.

gloster_f9-37.gif
 
Thanks for the comparison drawing.
Think we know well enough that early radial engine installation is not that streamlined as mid-war V-12 installation, collector exhaust means lot of exhaust thrust is lost, the ram air intake sticks out vs. the one that blends in the wing. 2 x 200-250 HP less on the Gloster.
Weight does not play that much a role in quest for speed. for example, extra 1000 lbs on the P-51 meant just 3 mph less top speed at 24500 ft.

And possibly not, but it does make me wonder what the point is.

The point is twofold:
- making the level playing field, in order not to compare no-combat-capable Gloster with combat-capable Me-210
- arriving on realistic performance figures for the 'Merlin Gloster', per opening post here
 
- making the level playing field,

Either you believe the 360 mph figure is not accurate or you believe the prototype didn't have full equipment, or both. I'm pretty sure it didn't have full equipment, and can take this into account. You mention ram air far too often, as well as exhaust thrust. It's only a small factor, and the measurable comparisons don't exist in any meaningful way, while you are willing to posit that 1000 lbs means nothing at all. The engineering department at NAA went through considerable effort to remove that weight from the Mustang. The Taurus was a very small diameter radial, which reduces the drag, while the absence of the need for a radiator doesn't seem to enter into the equation.

As I recall, the Gloster with Taurus handled beautifully, while the Kestrel required additional effort, not applied. The Me-210 was the landmark in the achievement of crap. The Hercules/Beaufighter had flaws, and the Merlin/Beaufighter had more, on the same power. Aircraft are like a box of chocolates, and I'm no longer hungry.
 
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