Vickers FB5 gunbus.

[Barry Hickson]

G'day All!
Just wanted to get some info on the venerable old Gunbus.
Does anyone know or has read if the Gunbus could preform an Immleman Turn?
I know its ability was limited by its lack of power but I have not read much about its maneuverability.

[Volker_Nemsch]

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First, let me say that this is just a guess based on some technical data.

I checked the old Thetford book "Aircraft of the 1914-1918 War" and found the following technical data in connection with the Vickers F.B.5 Gunbus:

Top speed 70 mph (112 kph)
Landing speed 41 mph (66 kph)
Engine power 100 hp
Max. weight 2,050 lb (930 kg)

For comparison, the Fokker E.I had an 80 ph engine, a top speed of 80 mph (129 kph) and a max. weight of 1242 lb (564 kg). Even on this low level of "high performance aviation" there are considerable differences.

For 1913/14 the performance data of the Gunbus were not bad, for in late 1914 and early 1915 the prey was often faster than the hunter. And my guess is, that the low powered Gunbus was quickly loosing height during a dog-fight (a term then unknown) and that a quick zoom would have resulted in an immense loss of speed and therefore resulting in a stall – the difference between top speed and landing speed (near stall speed) was only a meagre 29 mph.

So flying an Immelmann turn in a Vickers F.B.5 Gunbus? Well, that’s something I wouldn’t try. This does not mean that it never was tried...

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[dglewwe]

Is it the maneuver of the time or the current idea?

If the former I'd guess* possible, if the latter I'd say no - but then I doubt the Fokker could do one of the latter, either?


* based on nothing but opinion

[Volker_Nemsch]

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... that "aerobatics" meant everything apart from starting, landing and getting your flying machine as safely as possible from A to B.


Fokker was a brilliant pilot and serval experienced military pilots expressed their admiration for his flying skills. And, because he also was a good businessman, before the beginning of the Great War Fokker made several successful flights to promote his new "Fokker M 5" (the basis for the later Fokker E-series).

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[Barrett]

We gotta define our terms. "Immelmann turn" today means a half loop with a half roll to upright at the top.

Not many 1915 aeroplanes could reliably do that. The late Jim Appleby, who built and flew two reproduction (not replica) Eindeckers said "Nobody did an Immelmann in that airplane--INTENTIONALLY!"

As oft discussed elsewhere on the Forum (and a heartfelt thanks again to Kommodore Scott) what was called an Immelmann Back Then was far more likely a chandelle Now. Accomplished the same purpose: a vertical reverse.

[Barry Hickson]

So is the consensus that the Gunbus "may" have been able to preform the WW1 version of the Immlemann if the Pilot was brave enough?

[Volker_Nemsch]

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"Nobody did an Immelmann in that airplane--INTENTIONALLY!"

That’s also my opinion. The early military pilots mostly were aware how limited the performance of their machines was and so "the original Immelmann turn" may have been flown accidentally, because it included the risk to lose control about the aircraft and (due to much lower heights) there was the risk of a crash before regaining control.

Of course technically brilliant pilots such as Fokker, Sopwith, Garros or Suwelak knew the limits, since they had a much deeper knowledge. They were more than just "flying soldiers". Maybe a soldier (such as Immelmann) developed a useful turn out of the "pre-war aerobatics" Fokker showed him?

But we have a flying F.E.2. Maybe people flying this machine (although technically more advanced) can tell us more about the safe and unsafe flying manoeuvres of a 2-seater pusher.

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[Barrett]

What's little realized: certainly in the 1915 era, into 16, recovering from inverted at the top of a loop likely would involve considerable loss of altitude. While the aeroplane is rolling upright, it's descending of its own accord, in addition to the pilot's preferences, to regain airspeed. That's one reason why power-to-weight ratio was increasingly important.

[Volker_Nemsch]

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... when we are talking about the Vickers F.B.5 Gunbus and call it something like a "fighting aircraft". Well, it was armed with a machine gun, but it dated back to a time when aviation meant to fly in a straight line from A to B and some very careful flown manoeuvres in order to avoid clouds, to start without stall and to land safely again. It was a typical pre-war design.

Even by 1915 standards the Gunbus gunner was more like a hunter, sitting on his raised hide, while the pilots of the tiny Moranes and Fokkers were real hunters in their relatively nimble and quick machines. They really could attack the enemy in a hawk-like fashion (or retreat if necessary) while the Vickers crew could only hope that they could surprise an unwary enemy or that the (faster) enemy accepted a fight. And just being "heavily armed" is not a guarantee to have a good fighter aircraft - here the Messerschmitt Bf 110 of another conflict is another example for this wrong idea.

But even if this early military aircraft had a mediocre performance the German pilots surely treated them with respect, since they were armed and dangerous if they got within the range of the gunner.

Just an idea...

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