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Should be faster. The V-3420 was not a thing in this timeframe, though.
OTOH - how about a DB-7 with V12 engines?
Could do well. V-1710 with low altitude rating would make for a fast low level bomber.
To move away from the West, let's take a look at the East.
Yokosuka made the D4Y, a fast bomber on engine no better than DB 601A. Good for ~335 mp/h, with excellent range, although fragile due not having the self-sealing tanks in a heavily contested environment. With better engines, it did ~360 mph. Carrier- and dive-bomb capable, with Fowler flaps.
No great secrets wrt. why it was reasonably fast - it was a small bomber, with a bomb bay.
In service from mid-1942. Not too late?
What about Fokker T.V.
But with improved aerodynamics (nose section especially), the crew reduced to 3 and with more powerful engines.
R-1830 at first and R-2800 later?
The bomb bay was spacy and probably could be enlarged if required.
Aero A.300.
"Almost" in service to the Munich.
Up to 1,000 kg internal. Needs better engines if developed further.
Aero A.300 - not faster than Blenheim? Will need Merlin or something like that.
In those articles, Mercury IX is rated at 830 hp (2750 rpm, 4,400 m) and Mercury XV at 930 hp with no rpm/alt info.
The latter with 100 octane, probably? This site gives 995 hp to Mercury XV with 100 octane:
Bristol Engine Co: Mercury - Graces Guide
Could Aero A.300 reach 480-490 km/h with 995 hp, what do you think?
Aero A.300 - not faster than Blenheim? Will need Merlin or something like that.
T.V. - bigger than B-25, with half the engine power? R-2800 will be required, indeed.
I think we are falling into the famous wiki trap of listing the max everything of plane A (max range, max speed, max bombload) and not on plane B.
we also have the problem of the text not matching the specification list.
from Joe Baugher's web site for the B-25D but edited.
"Engines: Two Wright R-2600-13 Double Cyclone fourteen-cylinder air-cooled radials, each rated at 1700 hp each for takeoff, 1500 hp at 2400 rpm.
Performance: Maximum speed 284 mph (457kph) at 15,000 feet.
Cruising speed 233 mph (375kph) at 15,000 feet.
Range 1500 miles with 3000 pounds of bombs.
Weights: 20,300 pounds empty, 34,000 pounds maximum loaded.
Fuel: The fuel capacity consisted of four tanks in the inner wing panels, with a total capacity of 670 US gallons. In addition, a 515-gallon tank could be installed in the bomb bay for ferrying purposes, bringing total fuel capacity to 1255 US gallons. Later versions had additional auxiliary fuel tanks in the outer wing panels. Later versions could also have 125-gallon tanks fitted in side waist positions, a 215-gallon self-sealing fuel tank installed in the bomb bay, and provisions could be made for a droppable 335-gallon metal bomb-bay fuel tank.
Armament: Two 0.50-inch machine guns in dorsal turret. Two 0.50-inch machine guns in retractable ventral turret. One 0.30-inch machine gun in flexible mount in the nose. Starting with B-25D-5 the 0.30-inch nose gun was removed and replaced by a flexible 0.50-inch machine gun in the extreme nose and two fixed 0.50-inch machine mounted in the nose and firing through holes cut into the side of the Plexiglas glazing.
Normal bomb load was 3000 pounds but could be increased on the B-25D-1-NA with external underwing racks to a maximum of 5200 pounds."
Sometimes the bomber version B-25s were rated at 5200lbs with a pair of 1600lb AP bombs and torpedo, at totally useless combination that was never used in service.
If the above data is true then the B-25 could carry 3 times the bomb load of a Blenheim over the same range (I am not going to argue over 100 miles out of 1400-1500) and do it faster.
Chances of the Fokker T. V. even being close are about zero.
Nice cut away here.
(http://imgur.com/lFt3QVI)
but raises a bunch of questions, Co-pilot manned the dorsal gun? Radio man left his radios and was responsible for both side window guns and the ventral gun?
This thing did NOT have a small fuselage and the drag would be fairly high, you are going to need a LOT of power to get it to go very fast.
Why I find T.V vs B-25 comparison interesting... T.V was introduced 3-4 years earlier and with worse aerodynamics and much weaker engines was not so much behind B-25 in speed and internal bomb load.
The first 24 B-25s were supposed to do 322mph, BUT they had no armor, no self sealing fuel tanks, a single .30 cal in the nose, a single .30 cal gun out the top, much like the Fokker (no turret) a single .30 cal that could be shifted side to side in windows in the fuselage and a single .50 cal in the tail operated by a man laying prone.
Stating with the 25th plane they got armor and self sealing tanks. Internal bomb load was 3,000lbs. speed dropped to 315mph. B-25A
On the 65th plane the top and bottom turrets show up, the tail gun disappears as does the waist gun. Speed drops to 300mph. B-25B
Try to bring the T.V up to the standards (armor and protected tanks) of late 1940 and see what happens to speed/range/bomb load.
Compared to what? The Ju 88 had a maximum speed of over 290 mph, there weren't many other bombers capable of that speed in 1939/1940. 'Fast bomber' is a relative term and therefore in the time period Tomo stipulates, 250 to 280 mph is considered fast, especially when the fastest already in service in the mid-30s could just exceed 200 mph. Before the He 111, Do 17 and Ju 88, the Ju 86 couldn't even exceed 200 mph and the Ju 52 bomber transport, couldn't exceed 120 in level flight. Before the Whitley, Hampden and Wellington the RAF had the Overstrand, at a paltry 140+ mph maximum speed, still faster than the Ju 52/3m mind you.
The Bf 162 anyone? It was certainly fast, but could only carry 750 kg of bombs.
The aircraft's first flight was made by the prototype Ju 88 V1, which bore the civil registration D-AQEN, on 21 December 1936. When it first flew, it managed about 580 km/h (360 mph) and Hermann Göring, head of the Luftwaffe was ecstatic. It was an aircraft that could finally fulfil the promise of the Schnellbomber, a high-speed bomber.
...
The fifth prototype set a 1,000 km (620 mi) closed-circuit record in March 1939, carrying a 2,000 kg (4,400 lb) payload at a speed of 517 km/h (321 mph)
But I'm just trying to imagine what T.V could do if modernized as I mentioned above. Could it meet the criteria set in the Tomo's start topic. B-25 was just for a reference.