Messerschmitt 109 Improvements

[Ivan1GFP]

My apologies if this is seen as provoking a discussion that digressed and degenerated a bit, but I believe the original topic had a lot more life.

The subject of Toe-In versus Toe-Out was brought up but I believe it didn't get proper coverage.
It IS a geometry problem but not quite what folks were discussing:
The big problem is the NEGATIVE CAMBER of the wheels because of the angle of the struts from the fuselage.
The Spitfire and Wildcat also have very narrow track landing gear but this isn't as much of a problem because their wheels have POSITIVE camber when unloaded and closer to Zero camber when loaded.

With Negative camber, the wheels may have neutral toe when the fuselage is level but in a 3 point attitude, there is unavoidable severe Toe Out.

If I were selecting bad features of the 109F to correct, it would be the following:
1. Correct the camber of the landing gear. It was corrected to some extent in later models but ended up putting bulges in the wings. Perhaps the camber could be changed with a link of some kind as the wheel retracts.
2. Make the Ailerons internally balanced and add tabs to lighten them a bit at high speed. An external mass balance just isn't right on a high performance aircraft.
3. Add more aerodynamic balance on the elevators to lighten forces at high speed.
4. Install an improved canopy similar to the Erla-haube. (Or go to a sliding canopy which is a bit more redesign.)
5. Add a cockpit adjustable Rudder Trim and increase the height of the fin for less swing at take-off.
6. Add a bit more wing area perhaps with extended tips or a less extreme take on the carrier versions.
7. Clean up the armour glass installation on the windscreen. The bolt on stuff is just bad.

This would be the most extreme change and I have no idea of the engineering changes required but:
Lower tail by reshaping the aft fuselage. This would correct the ground angle that the elongated tail gear was meant to correct.

I do not believe enlarging the fuel tank rearward would be a good idea because it is already way aft of the CoG of the aircraft. If possible, the fuel should all be located as close as possible to the CoG so that trim changes as little as possible.
The German drop tank system already has some pretty good advantages over the Allied systems.

Opinions?
- Ivan.

 

[Mangrove]

Opinions?

Finnish VL Pyörremyrsky was basically a project to try to include all of the good factors of the BF 109, use the same engine, but with some of the faults of the Messerschmitt fixed.

 

[GregP]

I am leaning towrd having stub wings permanently attached to the fuselage and bolting the existing wings onto the stubs. The stub wings need only be about 1.5 - 2.5 feet wide and the gear would be moved ourward as well. You could put self-sealing fuel tanks in the stub wings.

I like the idea of adjusting the wheel angle with links but would prefer moving the gear outward and retracting inward as on the Me 209.

Not quite sure why the controls got so heavy at speed, but correcting this should have been a poriority and it COULD have been been corrected or at least made much better. Had the Luftwaffe insisted on fixing this early-on, it would have been a non-issue later. Ditto the lack of rudder and aileron trim ... there is simply no decent excuse for not having it.

Improving the windscreen would seem to be easy on the surface. Every WWII fighter I have sat in has a better windscreen than the Bf 109, so improvement wouldn't seem to be too big of an issue.

If you lower the horizontal tail you create another issue ... susceptibility to FOD damage. These planes operated from farmer's fields and rocks can easily render a plane unserviceable by causing damage to the leading edge of the horizontal tail. When I was at Reno in 2011, Rare Bear managed to poke a hole in the starboard horizontal tail leading sdge on a paved runway. The repair wasn't too tough, but wartime planes maybe could have had a thick leading edge specifically to avoid this situation ... or leave the tail high.

Since we're talking improvements anyway, I would investigate eliminating the slats. They almost never opened at the same time and induced yaw when they opened asymmetrically. Once open, they were fine. The question is why have slats at all? The fighters that didn't have slats didn't seem to suffer from the lack thereof. Maybe all that was needed was some washout and slightly more wing area. Whatever, it could be examined in a wind tunnel and/or on one or two individual airframes. Seems like an unneeded gimmick that, while it worked after a fashon, was not anything close to optimal.

I'm glad you started the topic again and hope it stays on track. I would reitterate, the Bf 109 wasn't a bad fighter at all. We're just talking about improvements that could have been made, not running it down as a warplane. It well might be that these changes would be extensive but, if they had been made early-on, they could have made quite a difference.

 

[Milosh]

They almost never opened at the same time and induced yaw when they opened asymmetrically.

The first part is a bit of a myth Greg. Mtt investigated wing fences which would have been an easy 'fix' but the slats were the better option.

 

[GregP]

Might have been a myth on the German Bf 109's, but the same slats on the Hispanos definitely opened asymmetrically if the ball wasn't centered. In the heat of battle, keeping the ball centered might have taken a back seat to other considerations such as keeping your head on a swivel.

 

[Shortround6]

The slats help a lot with landing, at least in theory, they start to add lift when the angle of attack exceeds 13-14 degrees? Nose up attitude for 3 point landing plus glide slope? Helping maintain aileron control at low speed is probably as important as actual lift. Max lift not occurring until over 20 degrees. A number of English aircraft started with slats and dropped them but then a Halifax shouldn't be operating at 16-24 degree angle of attack anyway

Mid 30s say a lot of new things being tried but it took a few years and a LOT of experiments and experience to sort out what really worked in the real world and what didn't. Some plane designs had new "high lift" features added just to see what happened and some were dropped when they found they didn't help in many of the planes fight regimes, even though a different type plane (with different missions, flight characteristics) might benefit from the same device.

 

[bobbysocks]

what about swaping the slats for standard adjustable flaps?

 

[cimmex]

Why nowadays people always want to improve the Bf 109? The RLM was the only authority who could request improvements. But they never did. There must be a reason.
cimmex

 

[stona]

Why nowadays people always want to improve the Bf 109? The RLM was the only authority who could request improvements. But they never did. There must be a reason.
cimmex

Because there was a war on

Lowering the tail might cause all sorts of aerodynamic problem, masking the rudders or elevators for a start. It's a non starter. For example, the only way to get an early tail dragging Me 262 off the ground was to apply the brakes to raise the tail as the elevators had no authority, being masked by the fuselage.
The rest seem to me at least feasible.
Cheers
Steve

 

[Shortround6]

what about swaping the slats for standard adjustable flaps?

They don't do quite the same thing. The Flaps may improve lift at lower angles of attack but they do nothing for maintaining aileron effectiveness at low speeds.

 

[stona]

The Bf 109 already had adjustable flaps, just over 50% of the wing span and 42,5 degrees maximum deflection. An interesting feature was that they were linked to the ailerons which also drroped progressively with the flaps. With flaps fully down the ailerons drooped by 11 degrees.
The slats served a different purpose, not only at low speed but also high angles of attack, by increasing lift and preventing the wing from stalling. The mechanism by which they work was not properly understood in the 1920/30s and is rather complicated. Pre-war designers just knew that they worked.
How do the slats improve aileron effectiveness at low speed?
Cheers
Steve

 

[Shortround6]

Slats (and fixed slots) keep the air on the top surface from separating (stalling). An Aileron trying to operated in a stalled or partially stalled (disturbed) air-stream looses effectiveness. The slats/slots do not "improve" aileron effectiveness over what it would be at low speed with the wing un-stalled, but they help maintain the effectiveness at high angles of attack right before the stall or even a bit during it. Many wings do not stall all at once but progressively from the wing root out or from the tip in. The slats/slots keep the area of the wing they affect (pretty much the area behind them) from stalling, at least up to a point. The root/ mid wing area may be stalled and the plane loosing lift and mushing but if the outer wings are NOT stalled the ailerons allow some lateral control.

 

[davebender]

Me-109 was the most successful fighter aircraft in history.

Why not improve the rest so they become as successful as the Me-109 series?

 

[Tante Ju]

Since we're talking improvements anyway, I would investigate eliminating the slats. They almost never opened at the same time and induced yaw when they opened asymmetrically. Once open, they were fine.

I have never read about yaw. The 109 had low directional stability, but this was perhaps due to the tail design. As for the slats, the British noticed some aileron buffeting and stick floating while the slats were opening (which may well only last a fraction of a second) and somewhat disturbing aim, but this may well have been a peculiarity of the single example they were testing. Mark Hanna flew the 109G and noticed there was no disturbance around any axis when they deployed. Either the kinematic design improved or it was just that 109E that had badly set up slats.

The question is why have slats at all? The fighters that didn't have slats didn't seem to suffer from the lack thereof. Maybe all that was needed was some washout and slightly more wing area.

Because they had positive stabilizing influence at high angle of attack, that's why subsequent fighters, even jets had them. The 109 was known to be an extremely well controllable plane in stall and devoid of any nasty stall characteristics. That's how it actually beat the Heinkel design in stall tests. The rest is history. Most planes today have some sort of slat-like high lift device in the leading edge, it cannot be such a bad idea.. WW2 fighters without slats sure did not suffer from the lack of, but sure as hell did not benefit from that either. More wing area means more drag, all the time, and less top speed. A slat is practical since it only adds drag when its needed. And that's basically throwing the baby out with the bathwater - all of the great performance characteristics essentially came down to its extremely high power to weight/drag ratio, following Willy's idea of an air frame with the lowest possible weight and drag with a very powerful engine.

Whatever, it could be examined in a wind tunnel and/or on one or two individual airframes. Seems like an unneeded gimmick that, while it worked after a fashon, was not anything close to optimal.

Messerschmitt did investigate boundary layer fences on the 109 and decided against it. They weren't fanatic about slats, the Me 210 did not have them initially, they added them later on, when landing characteristics were found to be too challenging.

People also seem to start out from what was actually mass produced and assume that no background research was done. Its a false presumption, a lot of things were tried and tested - there were even 109s with butterfly tail units, the Me 209 which was found to be a bit faster but less maneuverable, 109H with larger wings etc - but the ones that weren't introduced were simply dropped because they simply did not worth it.

 

[Ivan1GFP]

The idea of moving the entire tail down probably would not cause any blanking at take-off because the tail would be at the same relative position to the wing. The only difference would be the angle of attack of the wing and the horizontal stabiliser. The idea is just to change the ground angle a bit with a fuselage shaped more like a Heinkel 100 but without the goofy long tail gear strut. Perhaps the payoff would be too little.
The reason I believe this would be a fairly simple change is because the 109's structure in the tail is VERY simple. The improved ground angle should also help with directional stability.

Slats seem like a better idea than washout. The problem with washout is that it generally increases drag because if one section of the wing is at an optimal angle of attack, other parts would not be. The uneven opening of the slats was a known problem with the 109E which is why the bearings were changed for the 109F and later. If they are operating properly, they should deploy because of their own weight and be retracted by air pressure against the leading edge.

I am also not convinced the idea of a single radiator under the fuselage is a good one. It would absolutely require that the wings be redesigned for bomb racks and drop tanks and might need quite a lot more engineering. Also, keep in mind that this is where all the spent shell casings end up.

I am generally not a big fan of asymmetry, but how about mounting a 13 mm MG only on the starboard side but set back enough to be in line with the supercharger? I don't happen to remember what other equipment is located there other than the engine mounts.

- Ivan.

 

[DerAdlerIstGelandet]

Me-109 was the most successful fighter aircraft in history.

Why not improve the rest so they become as successful as the Me-109 series?

I am a 109 freak, my favorite acft all time, but I question whether it was successful by design or simply because of the situation it was forced in.

 

[Milosh]

Me-109 was the most successful fighter aircraft in history.

Why not improve the rest so they become as successful as the Me-109 series?

When there is 30,000+ built, and the only other option is a Fw190, it is not hard to be successful.

 

[DerAdlerIstGelandet]

When there is 30,000+ built, and the only other option is a Fw190, it is not hard to be successful.

My point exactly.

 

[GregP]

Hey guys,

I tried my best to state this at the start. I am not running down the Bf 109. What I was saying is that changes should have been explored. It well might be they WERE explored and discarded ... but it also well might be nobody tried for major improvement in multiple areas. I don't know and don't care a great deal.

The changes I suggested were just that, suggested areas for investigation ... except for the lousy windscreen, controls that stiffened up at combat speeds, and the lack of trim. These were major. The rest were areas to LOOK at, not areas that would make a major difference.

 

[Tante Ju]

Whats so lousy about the windscreen, being too steep, too small or...?