Me-309: how good was it?

[spicmart]

Designers tried to install one ton engine (dry) and 7 guns (3 of them being automatic cannons) on a wing half size of what Tempest or Corsair had. Talk about excessive wing loading to get pilots killed - no enemy action needed.

I'm wondering what the hell were they thinking in the first place with such a wing load?

 

[tomo pauk]

Smaller wing in theory means lower drag = more speed. MTT succeded when applying that formula on the Bf 109, and were probably expecting that it will work this time. It did not.
Lets recall that Fw tried the small wing approach with Fw 190, however the bigger wing (that quickly became standard wing) lowered the wing loading to the values accepatble for most of the pilots to handle.

 

[spicmart]

Smaller wing in theory means lower drag = more speed. MTT succeded when applying that formula on the Bf 109, and were probably expecting that it will work this time. It did not.
Lets recall that Fw tried the small wing approach with Fw 190, however the bigger wing (that quickly became standard wing) lowered the wing loading to the values accepatble for most of the pilots to handle.

They sure took this approach to the extreme although they should have known of the fallacy of it. But looking at the plane putting on an enlarged wing might have been possible.

 

[tomo pauk]

They sure took this approach to the extreme although they might have known of the fallacity of it. But looking at the plane putting an enlarged wing might have been possible.

It would've certainly been necessary.
The Me-209 (of 1943/44) knida shows that MTT lerned the lesson re. wing size vs. weight of A/C, a bit too late, though.

 

[spicmart]

Keep the wingshape (looks good..) and enlarge it to about 22-23 sqm. Not sure about keeping the laminar flow wing profile or not. Maybe extend the rear fuselage a bit for more leverage.
Also use larger control surfaces. MTT would mostly use comparatively small control surfaces. Don't know what the advantages are as other nations tend to attach larger ailerons, rudder and elevators in their planes.

 

[blueskies]

I'm wondering what the hell were they thinking in the first place with such a wing load?

The very heavy cannon armament was for the bomber interceptor/heavy fighter version, and that was with 5 guns not 7. The normal air superiority variant had 3 guns in the fuselage.

Smaller wing in theory means lower drag = more speed. MTT succeded when applying that formula on the Bf 109, and were probably expecting that it will work this time. It did not.
Lets recall that Fw tried the small wing approach with Fw 190, however the bigger wing (that quickly became standard wing) lowered the wing loading to the values accepatble for most of the pilots to handle.

I think Robert Lusser doesn't get enough credit when it comes to the 109s design. After he left it seems like messerschmitt just couldn't put out a winning design, excluding the 262. The 190s smaller wing was for the original engine, the switch to a larger wing was undertaken when the 801 was chosen as the preferred power plant.

They sure took this approach to the extreme although they should have known of the fallacy of it. But looking at the plane putting on an enlarged wing might have been possible.

The bomber variant of the 309 would have had a 75cm extension to the wing.

It would've certainly been necessary.
The Me-209 (of 1943/44) knida shows that MTT lerned the lesson re. wing size vs. weight of A/C, a bit too late, though.

The 209II started off as a lark by an engineer in his free time during 42. Initially it was a simple reworking of the 109 wing with the landing gear retracting inwards, as tested on the v31. However it became obvious that this wouldn't be viable as too much of the structure of the wing needed to be changed to make the landing gear work. This lead to a new thinner wing with pretty much the same planform as the normal 109 wing.

Keep the wingshape (looks good..) and enlarge it to about 22-23 sqm. Not sure about keeping the laminar flow wing profile or not. Maybe extend the rear fuselage a bit for more leverage.
Also use larger control surfaces. MTT would mostly use comparatively small control surfaces. Don't know what the advantages are as other nations tend to attach larger ailerons, rudder and elevators in their planes.

The 309 didn't have a laminar flow wing. By and large german aircraft companies preferred non-laminar sections for a few reasons, with the big exception being B&V who had quite a few designs with laminar flow airfoils.

 

[spicmart]

Do you know the reasons why german manufacturers preferred non-linear sections?

 

[blueskies]

Do you know the reasons why german manufacturers preferred non-linear sections?

I'm assuming you mean non-laminar. Firstly the drag rise near critical mach is much greater for a laminar section than the mostly naca derived sections typically used in Germany, and this is the prime reason why they were usually shied away from. Secondly were the issues with surface finish, which I think most companies correctly realized would be unattainable given the war situation Germany was in. There is on account I've read of Messerschmitt showing a wing ripped off a P-51 to some of their workers and imploring them to try and improve the quality of their work, essentially telling them that this is what they were up against.

Additionally pretty much all German aerodyanmicist were in agreement that the trailing edge angle was the most important factor for high speed transonic airfoils. I don't know what bearing this had on their thoughts of laminar flow sections, but perhaps its part of the reason.

 

[spicmart]

I'm assuming you mean non-laminar. Firstly the drag rise near critical mach is much greater for a laminar section than the mostly naca derived sections typically used in Germany, and this is the prime reason why they were usually shied away from. Secondly were the issues with surface finish, which I think most companies correctly realized would be unattainable given the war situation Germany was in. There is on account I've read of Messerschmitt showing a wing ripped off a P-51 to some of their workers and imploring them to try and improve the quality of their work, essentially telling them that this is what they were up against.

Additionally pretty much all German aerodyanmicist were in agreement that the trailing edge angle was the most important factor for high speed transonic airfoils. I don't know what bearing this had on their thoughts of laminar flow sections, but perhaps its part of the reason.

Yes, I did mean non-laminar (a little bit late, sorry). But for subsonic flight the laminar flow profile offered unprecedented low drag even for a large design such as the P-51 which featured superior speed which much less power. The Me 109 for all its little size is very draggy compared. From where do you know these thoughts of German aeronautical designers?

 

[Csch605]

To make matters worse RLM cancelled funds for testing and development a year after the first prototype.

How many WWII era aircraft were production ready after only 4 prototypes and a year of testing? Not many I can think of. So we will never know for sure how a production model Me-309 would perform.

If looks mattered Me-309 would have been a world beater. But they don't.
View attachment 223347

Boy that looks like a Mustang.

 

[Koopernic]

The very heavy cannon armament was for the bomber interceptor/heavy fighter version, and that was with 5 guns not 7. The normal air superiority variant had 3 guns in the fuselage.



I think Robert Lusser doesn't get enough credit when it comes to the 109s design. After he left it seems like messerschmitt just couldn't put out a winning design, excluding the 262. The 190s smaller wing was for the original engine, the switch to a larger wing was undertaken when the 801 was chosen as the preferred power plant.

The bomber variant of the 309 would have had a 75cm extension to the wing.

The 209II started off as a lark by an engineer in his free time during 42. Initially it was a simple reworking of the 109 wing with the landing gear retracting inwards, as tested on the v31. However it became obvious that this wouldn't be viable as too much of the structure of the wing needed to be changed to make the landing gear work. This lead to a new thinner wing with pretty much the same planform as the normal 109 wing.


The 309 didn't have a laminar flow wing. By and large german aircraft companies preferred non-laminar sections for a few reasons, with the big exception being B&V who had quite a few designs with laminar flow airfoils.

The Me 309, Me 155 / BV 155 all had a laminar flow wing. This was the Germans own work. The Me 262 wasn't officially laminar but it's cross section effectively was, it lacked the reflex at the tail but had the key characteristics which was a maximum thickness near 50% so that there was a positive pressure gradient over as much of the wing as possible. It had been optimised for high speed flight. The Japanese had several laminar flow winged aircraft. They may even have beaten the P51A/A36 into service.

The P51 wing had been given to Ludwig Prandle himself to evaluate. He reported its good characteristics but said the laminar flow wouldn't work in real life due to surface contamination.

Willy Messerschmit's Fame as an aeronautical engineer rested on his developing wing sections with very good pitching characteristics. The handling of the Me 109 was very good with excellent spin recovery.

The Me 109 tolerance issues relate to the lack of tooling especially on models after the Me 109G6.

The performance issues relate to the following first figure is sped at sea level second at max sped
1 Performance of the DB605A engine up untill the DB603ASM
2 Bulges added for guns cost 6 kmh - 9kmh compared to faired over cowlings.
3 Loss of ability to retract tail wheel 3kmh to 4kmh
4 bulges over wings to fit bigger main wheel.
5 lack of wheel well covers cost 10kmh-14kmh

 

[swampyankee]

As an aside, the Bf109 used NACA airfoils. Indeed, NACA airfoils were used by many non-US aircraft of WWII, including those axis.

 

[Koopernic]

As an aside, the Bf109 used NACA airfoils. Indeed, NACA airfoils were used by many non-US aircraft of WWII, including those axis.

The Bf 109 used modified NACA airfoils. The Germans, at the AVA I think, had developed a system of describing modifications to basic NACA 4 and 5 digit airfoils. US engineers used this German developed modification system. The B58 Hustler used them. In the 1920s the Premier airfoils were the Göttingen series both Clarke Y and the new NACA series came out of these. The NACA was excellent and well tested and everyone used them.
The Go series remained in use for flying boats such as the Shorts Sunderland and the Martin clippers because they didnt require much rotation to generate lift.

 

[tomo pauk]

The Me 309, Me 155 / BV 155 all had a laminar flow wing. This was the Germans own work. The Me 262 wasn't officially laminar but it's cross section effectively was, it lacked the reflex at the tail but had the key characteristics which was a maximum thickness near 50% so that there was a positive pressure gradient over as much of the wing as possible. It had been optimised for high speed flight. The Japanese had several laminar flow winged aircraft. They may even have beaten the P51A/A36 into service.

The P51 wing had been given to Ludwig Prandle himself to evaluate. He reported its good characteristics but said the laminar flow wouldn't work in real life due to surface contamination.

So when talking about those German aircraft, we accept - hook-line-and-a-sinker fashion - that they have had laminar flow wing, yet the airfoil of P-51 will not cut it? Germans have measured wing profile Cd, and arrived at numbers:
-Bf 109: 0.0101
-Fw 190: 0.0089
-Mustang: 0.0072
(per "Vee's for victory", pg. 338)

Willy Messerschmit's Fame as an aeronautical engineer rested on his developing wing sections with very good pitching characteristics. The handling of the Me 109 was very good with excellent spin recovery.

Willy didn't developed 2R airfoil, he used it on Bf 109 and 110 (and probably on 108).

[/QUOTE]