Messerschmitt 109 Design Problems

[kaki3152]

Two points immediately jump out:
Why did Willi not redesign the wing to accomodate armament in later versions of the 109? If the Allied powers and Italy and the Japanese could design a fighter airplane wing that could accomodate armament, why not the Germans. I dare say that if the 109F/G/K wing had been redesigned , fewer German aviators would have died becuase of the inherent speed penalty in underwing guns.
Also, why did they not incorporate a starter? I bet the German mechanics would have applauded. Or would that have made them lazy?
Finally, I read somewhere that one version of the 109F had a cut off valve that would conderve coolant in case of a leak. This was only used in the 109F and not in later versions?

[Graham Boak]

Messerschmitt was perfectly capable of designing a wing with guns, as the Bf 109E had such. However, he is not the only designer to avoid such, the Russians being perhaps the most obvious and Yakovlev is on record as giving at least partial reasons. Placing guns in the wings (inside or outside) increases the inertias in roll and yaw, making the aircraft less agile. The wings twist during flight, making accurate firing even more difficult.

A wing without guns can also be made simpler and lighter, which brings its own advantages. Once a wing has been designed without guns, then finding room for the weapon, ammunition, case ejection storage or chutes, and heating, is not a simple problem. Redesigning a wing to achieve this would mean major disruptions to the factory lines, with significant lost production. The gondolas may have penalised the 109 in speed, but even more so in agility, and this would have been the same with internal guns. As it was, the gondolas could be removed and the fighter returned to its optimum agility: with internal carriage much of the penalty would have been retained at all times.

Hopefully, of course, the gondola-equipped aircraft would be limited to bomber destruction, with the clean examples taking care of any enemy fighters. Messerschmitt did produce an internal fitting for the stubby MK108 for very late Ks, but this can only be regarded as a specialist bomber destroyer.

[kaki3152]

I guess my point is that the added weight to the wing structure would be more than compensated by the additional speed over gun gondola Bf-109s.
While the Germans did try to specialize, AKA the high Altitude Escort Staffel which always flew Bf-109s, it would have been better for the type of war they were fighting to use standardized Bf-109s with interior guns. Plus, any reinforcement to the Bf-109 wing would not be a bad thing (see BAlthasar JG-2)
asfar as the other two, it would have helped a great deal.

Oh well, the Luftwaffe probably thought the He-177 was the weapon that would win the war...Too bad they did not assign those resources towards Bf-109 improvements.

[Meyer1]

Hi kaki3152, I think you are overestimating the speed lost due to the gondolas. Here's a test of a 109 with Mk108 gondolas, only 6 km/h speed loss is reported:

http://kurfurst.allaboutwarfare.com/...08gondies.html

Since also inner guns would result in increased wing drag, I would say that the variation between gondolas/integrated should be negligible.

The weight is really the issue here.

In fact, I would say that, in the 109 case, the gondolas is a better solution, allowing more flexibility

[Graham Boak]

I understand the loss in speed due to the gondolas as more than that: I have 15 in my memory, but whether that was kph, mph or knots I can't say! kph probably. The loss in speed due to the drag of internally mounted guns would be significantly less than that of the gondolas. Weight has a negligible effect on maximum speed.

The 109 wing wasn't significantly weak, and there's no guarantee that fitting extra open spaces would have strengthened it at all. Carrying weight outboard on the wing does reduce the bending moment at the root, but the penalty on agility would over-ride that.

[Kurt Braatz]

I know from Guenther Rall that he hated wing cannons, no matter if gondola-mounted or integrated. They reduced roll rate and jammed in tight turns, thus making the whole system inoperable. Whenever he had been assigned a 109 with wing armament, he did not fly it in combat before these guns were removed. The opinions of aces like Guenther had a considerable influence on the Messerschmitt engineers, so they tended toward concentrating firing power as close as possible around the longitudinal axis of a fighter.

[Kurfürst]

Originally Posted by Graham Boak

I understand the loss in speed due to the gondolas as more than that: I have 15 in my memory, but whether that was kph, mph or knots I can't say! kph probably. The loss in speed due to the drag of internally mounted guns would be significantly less than that of the gondolas. Weight has a negligible effect on maximum speed.

The 109 wing wasn't significantly weak, and there's no guarantee that fitting extra open spaces would have strengthened it at all. Carrying weight outboard on the wing does reduce the bending moment at the root, but the penalty on agility would over-ride that.

Here's a recent post of mine on the subject, copied over from LEMB, for what it's worth :

Contrary to popular belief, the gunpods were not so hurting to performance, Soviet trials showed the following results with a clean and gondie G-2 : top speed 666/650 km/h at 7000m, time for a 360 degree turn at 1000m 20 sec vs. 22.6 sec, time to 5000m 4.4 vs 5.1 min.

Messerschmitt's specs for gunpods with ammuntion added 215 kg (135kg w/o ammuniton) to the takeoff weight, and a decrease of speed by 8 km/h at SL.

The weight increase was comparable to normal (inside-) wing installations, taking into account the weight of ammunition boxes, mounting rails for guns which the cannon gondolas contain in one single unit. As noted the gondola guns complete with housing etc., but without ammunition weight 135 kg for a pair of MG 151/20. In comparison, Fritz Hahn gives the installation weight of a pair of MG 151/20 complete with all accessories, but without ammo into the FW 190A-4/U8 as 126.7 kg.

As far as the drag goes, it would be interesting see the drag penaly for a internally mounted MG 151/20 in FW 190, but I've no such data; I have it for Spitfires though, which is detailed for various installations, understood for the change of speed at 360 mph. It goes as, as far as cannon armament concerned compared to the 'ideal' Spit, for our purposes, a Mk I without the cannons in the wing :

Two cannons : - 6.25 mph (ie. B-Wing
Two cannons and two cannon stubs : -8 mph (ie. C-wing)
Small bulge over wing : - 0.5 mph (late C-wing)
Large bulge over wing : - 1.5 mph (early C-wing)

This being compared to about 15 kph (~9mph) measured by the Soviets as speed penalty for gondolas at rated altitude of 7000m on G-2, and the 8kph@SL/~12 kph@VDH given by Messerschmitt in Leistungzusammenstellung Me 109G, here :
http://kurfurst.allaboutwarfare.com/...ragitems_table

The 109K-6's speed with the internal wing MK 108 cannons is given as apprx. 10 km/h slower than the K-4's at altitude.

Overall, it doesn't occur to me using gondolas were any heavier or draggier than using internal armament which would have resulted in some distruption of the aiflow near the surface, and some additional blisters on the wings. The gondolas may have been of greater surface area, but they pushed the gun well below of the boundary layer and probably made up for their greater size by causing less turbulance in the airflow. This was probably a very deliberate choice by Messerschmitt, who probably considered the need for such a heavy firepower involving three fast firing 20mm cannons only required in special cases, as so opted for removable gondolas which does not seem to hurt performance any more than internally placed cannons. When carrying gondolas, the early Me 109Gs could match the FW 190's firepower, as well as speed at altitude, rate of climb and turn.

PS : Spanish 109G 'Buchon' airframes had carried Hispano cannons inside the wings, so it was certainly technically possible..

Kurfürst! - The Messerschmitt Bf 109 Performance Resource Site
http://kurfurst.allaboutwarfare.com/

[Pilot]

http://www.virtualpilots.fi/feature/...09myths/#myths

http://mitglied.lycos.de/luftwaffe1/Carson/Carson.html

[RT]

Carson is not the best reference, further the worst problem is not a design one is that it will be necessary to hv at least 2 much more of them I mean of bf109, nd the pilots to drive them nd the gasoline to feed them,you don't win a war with best fighter but with the greater number, even against the P51, 1 to 1, the P51 hv soon diseappear of the european skies..


remi

[Franek Grabowski]

This must be a joke. P-51 outclassed any German fighter available and ruled the sky over Germany since spring 1944. The one cannot agree with Carson's arguments though.