Bf 109 wing guns

[silence]

Could a 109 take a pair of MG 151s (either 15mm or 20mm) in the same place as the Emils had the MG FF, instead of using the pods? If so, how many rounds do you think they could load up with?

 

[Aozora]

Could a 109 take a pair of MG 151s (either 15mm or 20mm) in the same place as the Emils had the MG FF, instead of using the pods? If so, how many rounds do you think they could load up with?

Not without a complete redesign and strengthening; even in the C, D E wings with the MG/FF a hole had to be cut through the main spar to accommodate the back end of the weapon, plus a hole in the lower wing to cover the 60 round ammo drum. The MG 151 was much longer and heavier;

MG/FF = 1.37m entire, 26.3 kg;
MG 151=1.91 m, 38 kg;
MG 151/20=1.77 m 42.7 kg

and there was no way the ammunition box and feed could have been added:

The K-6 wings had to be strengthened and modified for the MK 108 which was shorter than the MG/FF (1.057 m), albeit heavier than the MG 151/20 (58 kg): chances are the K-6s would have been real slugs to fly had they ever reached operational service.

 

[davebender]

I doubt that. 2,000hp DB605D engine provided a decent power to weight ratio even with the heavier armament.

 

[Aozora]

I doubt that. 2,000hp DB605D engine provided a decent power to weight ratio even with the heavier armament.

All that weight outboard on the wings would have changed the flight characteristics - the K-4 was already edgy at altitude, such that when III./JG 26 used K-4s equipped with gun pods they were sluggish and prone to stalling above 20,000 ft, and the pilots hated them; although the poor flight qualities were partly down to aerodynamics, the extra weight didn't help.

Secondly, that so-called 2,000 hp was actually 2,000 PS or 1,973 hp, and the DB 605 DC relied on using C3 fuel, MW 50 and 1.98 ata to achieve 2,000 PS, otherwise the maximum available power was 1,850 PS or 1,825 hp using either 87 Octane B4 fuel in conjunction with MW 50 (in DB configuration) or it could use C3 fuel without MW 50 (DC configuration) at 1.80 ata. There is no evidence that 1.98 ata was used on operations, except for some trials by III./JG 11 early in 1945.

Another question; what the heck was the K-6 going to be used for? If it was intended to fight against the American bombers, with the short range of the Mk 108 it would have been a sitting duck, without the ruggedness and extra armour of the Fw 190A-8/R-2. If it was intended for fighter-fighter combat those 2 extra MK 108s were a waste of time.

 

[GregP]

I don't know about the "Can't be done" part. Here is a shot of the wing of our Hispano Ha-1112 Buchon. This is the gun bay in the wing. You can clearly see the hole in the spars and there was ammunition, too. It had a 20 mm in each wing.

So it absolutely CAN be done ... with some redesign work along the way.

 

[cimmex]

So it absolutely CAN be done ... with some redesign work along the way.

Yes, build a complete new wing as the Spanish did…
cimmex

 

[GregP]

Yes, a new wing, but not completely new. Many parts from our Bf 109G-6 fit perfectly. The airfoil is the same at both root and tip as far as I can tell. The wing ribs are identical at those places anyway. The wingtip, ailerons, flaps, and many parts from a Bf 109G-6 fit. We are, in fct, unsing the wingtips from our Bf 109G=6 on the Ha-1112. The spars are different, and there is a small bulge on top of the wing for the cannon breech, but the planform is the same. I know the gear uplocks fit because we went to Bf 109G uplocks when the Ha-1112 uplocks went missing after 10 years of storage. I was on that project at the time we did that. We'll probably find the old ones now that the new uplocks are in place. It usually works that way.

The Ha-1112 is basically a Bf 109G from the firewall back, with the main difference being the wing armament due to the fact that the Merlin was never designed for cowl armament or for a cannon to fire through the crankshaft. The canopies are interchangeable.

But from the firewall forward, there are zero common parts. This one will have a Merlin 224 when it flies again. That would be a Packard-built Merlin 24. It will have DC-3 glider tug wide-chord prop cut down to match the contours of a Bf 109 prop.

 

[cimmex]

the Merlin was never designed for cowl armament or for a cannon to fire through the crankshaft.

Sorry, you cannot fire through the crankshaft at any engine, I think you meant "probshaft"
cimmex

 

[Aozora]

I don't know about the "Can't be done" part. Here is a shot of the wing of our Hispano Ha-1112 Buchon. This is the gun bay in the wing. You can clearly see the hole in the spars and there was ammunition, too. It had a 20 mm in each wing.

View attachment 253795

So it absolutely CAN be done ... with some redesign work along the way.

Interesting; Greg, do you know how the ammunition boxes and chutes were organised?

 

[silence]

Wiki says the guns were Hispano HS.404s. Sounds to me that this installation would be similar in size and weight to MG 151/20s, although in this case drum fed rather than belt.

 

[GregP]

Hi Aozora,

I don't but can find out. We have the manuals.

The guns were never in the wing when I worked on it and we have covered over the leading edge gun ports, but the breeches would be in the last bay back by the trailing edge, so the ammunition almost HAS to be back there. We also faired over the shell ejector chutes.

In one of the other departures from stock, we cracked a magnesium wheel and had two new ones machined from billet Aluminum. So they look great but are not stock Bf 109 wheels and ... I hate to admit this, we are currently using tires from a MiG-15 on these wheels. While they were being made, we used the wheels off our stock Bf 109G-6 to hold up the airframe. Once the plane is ready for airshows, we'll probably go back to stock Bf 109 tires.