As far as I can tell, there really never was an actual ‘Bf109A’. The closest thing I could see to a de-facto “A” model would be one of the “working prototypes” ( my term ), specifically the Bf-109V3, V4, and V5, all using the Jumo 210. From there they went right to the production “B” models. Those later “V” types were fitted with 3 guns, but when they sent a few to fight in Spain, the 3rd engine mounted guns always malfunctioned. ( it wasn’t till the “F” series to where the engine mounting ) guns proved successful )
I can’t find any performance data on the V-series performance, but we can speculate. Take a “C” series, with its 700 HP engine and its ability to hit 292mph ( at its optimum altitude ) and de-extrapolate what a V-series plane could do with 600 HP ( 540 was the continuous rating, with 600 HP available for 5 minutes )
Bf 109 A was the designation given the initial prototype (#758). Since the Jumo 210 was not yet available the Bf109 A was powered by a Rolls-Royce V-12. The designation of #758 was later changed from A to V1 to be compatible with the system of Versuchs numbers that was standard in the German aircraft industry.
The Henschel Hs 123 kind of fits the TUB bill. First flown in 1935, it was operational from 1939 through 1944. The task it filled best was close support of ground troops. Wolfram von Richthofen developed close support strategies that became vital during WW2. In 1944 von Richthofen requested that the then obsolete aircraft be brought back in to production.
Reynolds,
Only 10 aircraft were built between the Bf 109 A and the Bf 109 B. They had various engines, armaments and landing gear. So, each of those early variants would have had different characteristics. About 30 Bf 109 B aircraft were built to set up production. Some of these aircraft were used in competition to get international attention. Their performance was enhanced and exceeded stock aircraft. The Bf 109 C probably represented the initial production Bf 109.
I don’t know if you could build an ultimate biplane out of this; but perhaps you could further develop the Grumman F3F which had the retractable gear and enclosed cockpit you’re looking for. The engine possibly could have been replaced by the twin wasp used on the F4F Wildcat to increase speed.
And just to nitpick a little; a rotary engine is not the same as a radial engine. Rotaries were already on the way out by the end of WW1. Radials steadily developed between the wars; they didn’t make a sudden appearance during WW2. Inlines were also used during WW1 (Albatros, Pfalz D.III, Fokker D.VII, Se5a off the top of my head). There wasn’t a sudden switch to that engine type either.
Good spot there jayarrell.
Yes, the https://en.wikipedia.org/wiki/Grumman_F3F was the ultimate bipe, at least in the US. It was a 1934 update of a 1933 design first delivered in 1936. So well-aligned with the OP’s timeframe.
I suppose the OP’s question could be reduced to “If we made an inline version of the F3F, how much better / worse would it perform than the radial version?”
The tradeoff between inline and radial was always about weight vs drag. In a twit-post: “Vs, etc., are heavier; radials are draggier.”
Inlines / Vs need liquid cooling systems which need radiators. Radiators, pumps, lines, etc., are massively heavy as is the 10s of gallons of coolant. And the V engine itself is much heavier on a pounds per HP basis than is a radial. More massive crankshaft, lots more metal in the engine block than in the finned cylinders, etc.
Radiators are also surprisingly draggy structures. The fact they’re buried inside the fuselage makes inline aircraft look more slippery. But there’s a real ugly bunch of aerodynamics happening around the radiator inlets. The scoop on the bottom of a P-51 looks go-fast, but it produced about as much form drag as the rest of the aircraft put together. It was as highly optimized as could be designed in 1940; 1935 was a far more primitive era. The state of the art was advancing silly-fast in those days.
The bottom line there is that the drag difference between radials & inlines, although real, is not as obviously large as it looks just comparing their frontal areas.
A side concern about inlines in combat aircraft is that radiators and coolant lines are highly vulnerable to battle damage. They can’t be holed if they’re not installed = advantage radials. In fighters they also take up limited space that would otherwise be fuel or ammo. which also = advantage radials.
There’s not much doubt that if jets had never come along the end-state of piston aero-engine design would be V, W, or H engines, not radials. If somehow radials were still being competitive, they’d be water-cooled too. Once you go to a multi-row radial, air-cooling the rear bank(s) gets increasingly difficult, and the more rows the worse it gets.
e.g. The R-4350 (wiki) was about the end of the line for radials and they never really licked cooling problems in that 4th row of cylinders. Had they tried to grow radials beyond that point IMO it would have been as liquid-cooled . In the real historical timelines, jets came along in time to eliminate the need to further develop big radials. Or big V/W/H aero-engines either. So we’ll never know for sure how that would have worked out.
Returning to my twit-post: "Vs, etc., are heavier; radials are draggier."
Drag is proportional to speed, and weight is not. So for any given level of ICE tech, the faster the aircraft, the more the terms of trade favor the Vs et al. That doomed radials from the start; it was just a matter of which year airplanes would get fast enough to tip the scales for good.
And to close the loop on the OP’s Q from another POV. They did make an updated F3F. But not by replacing the engine with a V. Instead they removed the top wing and called it the F4F Wildcat.
I’m not opposed to a radial-engined TUB, but observational evidence showed all the really fast monoplanes at the start of WWII were in-lines. The BF-109, the Hurricanes and Spitfires, the Detwoine-520s. The A6M Zero didn’t come out until 1940, and the F4F was slower than the above-mentioned fighters. I know that the fastest piston-engined production fighter was the radial-engined F4F Bearcat, so radials could work, but I also know that the in-lines and V-engines were the speed demons of 1938 and 1939. The fastest biplane ever was a CR.42 Falco which had its radial engine replaced with an in-line DB605 engine, reaching 323 mph. If there are faster radials out there, I’d love to hear about them. Sounds like the Write R-1820 or R-1830 are good contenders.
We also know that monoplanes would win out in the end. This is common knowledge and common sense. The thought experiment is not to imagine how biplanes would have beaten monoplanes, but how they could have held on a little longer.
Right now, I’m liking the idea of a 1,000 hp engine, fabric-covered fuselage but aluminum wings, with interplane struts but no wires (like the HS 123). Enclosed cockpit, retractable landing gear, inverse gull on the lower wings to increase that inter-wing gap and reduce interference drag. A strong stagger, either positive or negative, would help this. A 4 .50 armament. At least, that’s what I’m envisioning thus far as the TUB based on discussion. I’d bet this TUB could reach 330 mph.
If you need a scenario to justify the creation of this beast, here you go: In an alternate history, airships and Airborne Aircraft Carriers become more prevalent in the naval scouting role, as the terrible accidents which plagued the design in the 1920s and 30s were avoided (we had more success stories like the LZ 129 and fewer tragedies like the Hindenberg and Akron). Monoplanes start coming out, but the Navy has a bunch of Airborne Aircraft Carriers designed around biplanes. They don’t want to lose the massive investment, and it’s cheaper to build an upgraded biplane fighter than to retrofit the whole ship for monoplanes.
I think the DB605 started to show up around 1939 so two radials contemporary (and possibly faster) to the db605 might be Pratt&Whitney R-2800 (started 1937, deployed 1940) or the BMW 801 (designed 1939, deployed 1940).
The R-2800 paired with inverted gull wings would allow a larger propeller as seen on the corsair which might improve performance.
Also, it’s my understanding the US Navy preferred radials for their planes due to the concern about battle damage mentioned by LSLGuy. That may or may not be a factor in choosing between inline and radial for your theoretical airborne aircraft carrier fighter complement.
Radials in fighters suffered another problem: They obstructed the view of the pilot on the ground. A taildragger fighter like the Corsair left the pilot pretty much blind when taxiing, requiring S-Turns so the pilot could see where he was going. The high horsepower radials also required huge propelloers, which in turn required long landing gear legs and made visibility even worse. The Corsair’s inverted gull wing was primarily for the purpose of allowing shorter gear legs, as longer ones were hard to engineer strong enough for carrier landings.
Finally, the combination of a light, high horsepower engine and a giant prop made for some hellacious torque issues. More than one F4U pilot flipped his airplane on its back on takeoff after applying power a little too enthusiastically.
It’s somewhat later in WW2 but the Kyushu Shiden was a radial engined pusher. Pusher planes were around in WW1 and by moving the engine to the back you eliminate a lot of issues like fwd visibility, centralizing the guns in the fuselage for more punch, and allowing a tricycle landing gear that allows you to simultaneously lift the rear for prop clearance, and make it easier to take off. As a bonus, you’re moving half a ton of steel to the middle of the body allowing you to play with c of g a bit. It also pushes the cockpit fwd for vis, and build a centralized wing box/ landing gear structure for more strength.
Yep, those are positive aspects. The negative traits of a pusher design include difficulty cooling the engine, the increased chance of FOD being kicked into the propeller by the tires, and the potential for prop strikes on enthusiastic rotation. Tricycle gear are great for ground handling, but not so good for unpaved runways, grass strips, etc. They are generally heavier and more complex than tailwheel configuratikns as well.
Unfortunately, everything in aviation is a tradeoff.
The most common trade-off being: “I trade the boring reality of being attached to the surface of a sphere for the AWESOMENESS OF FLIGHT!”
One thing I am learning is that the early BF-109s were nowhere nearly as good as I thought they were. 290 MPH is much easier to hit than the 360 I thought we would be targeting, and 2-3 7.92 machine guns are a lot lighter than 2 + 2 20mms.
The Russians actually continued using biplanes long after everyone else abandoned them. The Antonov AN-2 was in fact first built in 1947. It’s a large and slow biplane though, not the kind the OP seems to be interested in.
The Kyushu Shinden only flew a couple of times, and I have not seen reports of any handling issues, but the Curtiss Ascender canard had some nasty handling characteristics and no benefits in performance. See also the Westland Pterodactyl for another configuration.
If we want to stretch the definition of ‘biplane’, a Saab Viggen is close. It’s technically a monoplane with a canard instead of a tail, but the canard is quite large and contributes substantial lift. There are canard aircraft that have forward wings just as large as the rear wings, making them essentially biplanes.
Canards are theoretically more efficient than tails, because tails provide downforce which the wing has to absorb, leading to higher induced drag. In a canard aircraft, all surfaces provide lift. Why we don’t see more canard fighters I guess comes down to other factors.
The fastest true biplane on record was a WWII era Fiat CR42B, which set a record of 343mph in 1941 with a 1000 hp radial engine. Of course, it didn’t cruise at anywhere near that speed.
Biplanes could have been used for ground attack perhaps. The JU87 Stuka was famous for its ground attack prowess, but the thing was a dog in the air and completely vulnerable to enemy fighters. The key characteristic was lots of drag for almost-vertical dive bombing. And biplanes have drag in spades. Not sure why they were never used.
The Stuka had a cruise speed of only 130 mph, could only go about 210 mph flat out. Lots of biplanes around had that kind of speed, and the extra lift could have increased the bomber’s range (the Stuka had lousy range) and bomb capacity. It probably could have landed slower and been better at taking off from unimproved runways in the forward area.
But I’m sure there were good reasons, as aircraft designers hate leaving performance on the drawing board. Other limitations of biplanes probably prevented their use in that role, but I’m not sure what they would be.
More background for those interested: