# Bf 109 Landing Gear Geometry Issue



## GregP (Jan 15, 2014)

I was asked to clarify the landing gear geometry issue in the Bf 109 by a visitor to the museum last weekend. Attached is a front view drawing of a Bf 109.







When the tail is up, the tires are pointing parallel to eash other and straight down the runaway. No problem,

Now imagine for a second that the aircraft is pointing straight up, but is sliding forward in the direction of the belly. See the layout of the landing gear below the aircraft drawing. It is easy to see that if the gear is moving in the direction of the center arrow, the tires would be trying to slide outward from each side.

The aircraft cannot do this physically, but as the aircraft tips backward, the alignment track of the tires becomes increasingly toe out and, by the time the tailwheel is on the ground, both tires are toed out to a significant degree. The leanback angle is about 13°. If one tire or the other gets significantly more pressure (or weight on it) than the other, as in a crosswind where one wing lifts a bit, then the main gear will move in the direction of the wheel with the greater weight on it. If the pilot isn’t very quick with the rudder or brake or both, a groundloop can easily result.

Fitting a tailwheel lock helped but did not eliminate the problem.


----------



## stona (Jan 15, 2014)

Which is why a three point landing was the method taught to Luftwaffe (and modern) Bf 109 pilots. The problem with this is that in this attitude the view forward is poor and this makes it difficult to detect any swing developing, which brings us back to your last sentence  Inexperienced pilots tended to over react with inevitable results.
The geometry is the problem, the track of the Spitfire under carriage is significantly less than a Bf 109.
Cheers
Steve


----------



## Milosh (Jan 15, 2014)

The track of the Spitfire was ~6" less than that of the Bf109.


----------



## bobbysocks (Jan 15, 2014)

none of the front line fighters were too friendly to inexperienced pilots. but most allied pilots had 300+ hours before getting into one and then had several hours of orientation. the LW didnt have that luxury. i dont know how many hours they were getting before stapping into 109s late in 45 but it wasnt a whole lot......

_At some point during this period, Robert told me he was preparing for his first solo ride in the P-51. I advised him against the same mistake I made on my first take-off in a P-51. Had taxied to the end of the runway, got clearance to take-off,crammed the throttle forward and the horrendous torque developed by that very powerful engine and huge 4 blade prop jerked my nose about 30 degrees to the left and I darted off the runway. I knew if I reduced power I would mire in the January English mud and flip over. Not an option so I kept the power on, got it off the ground, got the wheels and flaps up and barely cleared the airport tower, so close that I took the wind sock with me. I am considering taking this with me on my next trip to Leiston airbase and advising them that I am returning the wind sock to their museum._


----------



## Aozora (Jan 15, 2014)

Milosh said:


> The track of the Spitfire was ~6" less than that of the Bf109.



The Spitfire's legs were vertical, with some toe-in of the wheels, therefore the legs were resistant to being pushed sideways. The legs of the 109 could be forced sideways by lateral forces because they were already splayed. In addition the structures that secured the 109's pivot points to their mounting points on the main bulkhead/spar were liable to be distorted by heavy landings (eg; the 109K):






take a look at the support structure 3, 21, 24, which was cantilevered and could be bent out of shape by lateral forces






vs Spitfire, supported at both ends and, being a tube, was less likely to be bent out of shape, albeit heavy landings could and did force the leg up through the wing (eg Seafires were prone to this)






Any lateral twisting or outwards movement was resisted by the hydraulic piston:


----------



## GregP (Jan 15, 2014)

I've never understood why Willy didn't toe-in the wheels so they were parallel in the 3-point attitude and toed-in during a wheel landing.

It would have corrected the worst of the faults and was almost ridiculously simple to accomplish. Then the swings on landing and takeoffs would have disappeared. Further, I'm surprised no crew chief came up with field mod to handle it.

It may well have been a case of simple pride that they didn't need a "fix" to handle this fighter, I can't say and would not care to speculate.


----------



## gumbyk (Jan 15, 2014)

GregP said:


> If one tire or the other gets significantly more pressure (or weight on it) than the other, as in a crosswind where one wing lifts a bit, then the main gear will move in the direction of the wheel with the greater weight on it. If the pilot isn’t very quick with the rudder or brake or both, a groundloop can easily result.
> 
> Fitting a tailwheel lock helped but did not eliminate the problem.



And a CofG that is well aft will make it all the harder to correct before it becomes unrecoverable.

Thanks for the clear, easy-to-follow description, Greg


----------



## Aozora (Jan 15, 2014)

GregP said:


> I've never understood why Willy didn't toe-in the wheels so they were parallel in the 3-point attitude and toed-in during a wheel landing.
> 
> It would have corrected the worst of the faults and was almost ridiculously simple to accomplish. Then the swings on landing and takeoffs would have disappeared. Further, I'm surprised no crew chief came up with field mod to handle it.
> 
> It may well have been a case of simple pride that they didn't need a "fix" to handle this fighter, I can't say and would not care to speculate.



Later variants, from the G-4 onwards had bigger mainwheels (from 650 x 150 mm to 660 x 160) and the geometry of the hubs was changed so the wheels were more vertical - the bigger wheels and more upright position meant that the kidney-shaped fairings were needed on the upper wings. Some late G-14s, most G-10s and all K-4s adopted larger 660 x 190 mm wheels which required the larger, rectangular upper wing bulges.


----------



## gjs238 (Jan 15, 2014)

GregP said:


> View attachment 252146



This drawing seems to show how an inverted V engine produces a sort of triangle shaped engine cowl with presumably less visibility restriction for the pilot.


----------



## GregP (Jan 15, 2014)

You're welcome for the text and, yes, I believe an inverted Vee does result in slightly better visibility over the nose and down, but seeing a small bit closer to the plane is not very important since almost ALL Vee engine WWII fighters have a poor, but better than with a radial engine, view over the nose.

None except maybe the Hellcat offer a view ahead. Can't see much down and to the side, but you CAN see the runway in front of a Hellcat about 80 yards ahead or so. At least, I can if sitting on a parachute.

In the air, all you have to do is bank slightly one way or the other to get a view ahead and down.


----------



## gumbyk (Jan 15, 2014)

I'm not convinced that visibility was such an issue.
I've been trained to use a combination of a point in the clouds, and peripheral vision to judge swing.

Reactions: Like Like:
1 | Like List reactions


----------



## Milosh (Jan 15, 2014)

An aviation expert (??) by the name of Crumpp has stated that 'toe out' is better than 'toe in'.


----------



## GregP (Jan 15, 2014)

Guess he never read a basic aerodynamic text that addresses conventional landing gear.

Of all the conventional gear WWII fighters, I believe the Bf 109 is the only one with toe out. I could be wrong there, but if so, not by much.


----------



## MikeGazdik (Jan 15, 2014)

Milosh said:


> An aviation expert (??) by the name of Crumpp has stated that 'toe out' is better than 'toe in'.



Not sure with airplanes, but in a car, "toe in" creates a very twitchy vehicle. Toe out is more stable. But a car does not go through the dynamics of a landing plane. 

I could see, toe in or toe out, that on landing this would be much more of a problem than on take-off. On take-off the load on the gear would become less important as speed increased, whereas on landing it would keep increasing and become more important.

And if load transferring from side to side, would create a toe-in and toe-out fluctuation, that would be tough.

This video shows a lot of directional instability on landing. (regardless, what an awesome looking, sounding, and flying airplane. love it ! )


----------



## stona (Jan 16, 2014)

gumbyk said:


> I'm not convinced that visibility was such an issue.
> I've been trained to use a combination of a point in the clouds, and peripheral vision to judge swing.



That's exactly what Luftwaffe (and I suppose everyone else's) pilots were trained to do. The problem was with inexperienced pilots who fund it hard to see the swing developing and then over reacted with coarse control inputs to correct it. The Bf 109 _is very unsympathetic _to clumsy reactions like this which is why it was challenging for these inexperienced pilots. There are numerous accounts from the 'experten' explaining how they kept the aircraft straight using well judged control inputs and, on landing, the brakes, but this was beyond the ability of some young pilots.
All these powerful, single engine aircraft of WW2 had adverse reactions to the engine torque, it's just that in the case of the Bf 109 this was compounded by various other factors and notably the title of this thread, to make it at the very least 'tricky' to land and take off. 

The Spitfires undercarriage track is indeed about 15cm/6" less than the Bf 109. I'd call that significant since for the reasons explained by others above the Spitfire does not suffer the same problems as the Bf 109, despite this. The problem lies with the geometry, not the width of the Bf 109s under carriage and yet time and time again, both in print and all over cyberspace, you will see the assertion that it was the Bf 109's narrow track undercarriage that caused innumerable landing and take off accidents.

Cheers

Steve


----------



## Lefa (Jan 16, 2014)

virtualpilots.fi: 109myths
What I've read, the Finnish pilots made ​​a stall landings.


And the take-off had no problems.

virtualpilots.fi: 109myths


----------



## stona (Jan 16, 2014)

Lefa said:


> And the take-off had no problems.
> 
> virtualpilots.fi: 109myths



Maybe you should go back and read what some of those reports say. Experienced pilots could handle the Bf 109 with relative ease but it is the less experienced pilots flying an unforgiving aircraft that were the problem. I can't quote every reference to this but Antti Tani sums it up nicely in the link you gave.

_Antti Tani: The first starts were often risky for many pilots. Many of them went in the forest, there was a "Messerschmitt corner " at Utti. _

It's also worth considering what the men who flew them at the time said. Even those who liked the Bf 109 would support what Tani said. Time and time again they comment on the difficulty that inexperienced pilots had handling the aircraft on or close to the ground. 

The reports from test pilots and experienced pilots on the Me 210 are invariably positive. For inexperienced pilots it was a different story. Johannes Kaufmann of ZG 1 wrote.

_'The Me 210 certainly impressed us... In comparison with the Bf 110, the Me 210 was faster.......climb performance was much better, diving characteristics conformed to the demands placed on it....The warning of danger on take off was justified as it needed some corrections to be made with rudder and the engines to stay on a straight line course........The approach and landing caused no problems.
Coming from Regensburg on the landing approach to Tours, I saw a most unusual picture. There were some crashed aircraft lying on the airfield which were evidently new and consisted of Me 210s......These crashes were due to exclusively to the young, still inexperienced pilots, so that a revised decision was forced upon the aeroplane. This came very quickly. The Me 210 was withdrawn...'_

The Bf 109 did not have some of the malicious handling characteristics of the Me 210 and was of course never withdrawn from service. It was nonetheless a handful for inexperienced pilots and killed a lot of them.

I will repeat that I don't believe that the Bf 109, as it entered service with the Luftwaffe, would have been accepted by the RAF.

Cheers

Steve


----------



## FLYBOYJ (Jan 16, 2014)

Ok folks, a few pokes here...

Describe "experienced." 

300, 400, 500 hours in tail draggers? 1000 combat sorties? A complete combat tour?

I've known pilots with just a few hundred hours who were more proficient and safe than pilots with thousands of hours. Additionally what kind of operations were 109 drivers subjected to? Planned calm mission sorties or hectic scrambles with little time to focus on basic aviating. Airfield conditions - moguls and holes all over the place or long and wide paved runways?

It was also mentioned that these aircraft were flown with no checklists, a huge risk factor recognized and remedied in the post war years as "lessons learned."

AFAIK the "old school" philosophy was to make 3 point landings as a norm, but as mentioned there are field of vision problems with the nose of the -109 being so long so peripheral vision would have to play here, throw in poor runway conditions as well as gusty crosswinds and this elevates the risk.
After considering this and reading some of the comments I guess is crystal clear why the tail dragger disappeared in post WW2 combat aircraft.


----------



## stona (Jan 16, 2014)

I don't think you can put a number on it. An old hand with many hours on other types might be able to apply that experience to flying the Bf 109 and would have a much lower chance of disaster. 
A young pilot with relatively few hours, but who had survived a number (pick one !) of take offs and landings in a Bf 109 would also be much less likely to come to grief.
Cheers
Steve


----------



## Lefa (Jan 16, 2014)

stona said:


> Maybe you should go back and read what some of those reports say. Experienced pilots could handle the Bf 109 with relative ease but it is the less experienced pilots flying an unforgiving aircraft that were the problem. I can't quote every reference to this but Antti Tani sums it up nicely in the link you gave.



I have read, and although Finland used the plane until 1954, I have not read than one fatal accident, some broken machines, though. If anyone has information about the Bf 109 accidents in Finland, put the information here. Of course they are some, but I have not seen statistics
I think a bad reputation came from Germany where late in the war, after very short pilot training, young pilots entered the plane.


----------



## stona (Jan 16, 2014)

Lefa said:


> I have read, and although Finland used the plane until 1954, I have not read than one fatal accident, some broken machines, though. If anyone has information about the Bf 109 accidents in Finland, put the information here. Of course they are some, but I have not seen statistics
> I think a bad reputation came from Germany where late in the war, after very short pilot training, young pilots entered the plane.



I don't know much about Finnish use of the type, nor how the Finnish pilots were trained. It must be probable that the Finns were able to provide better training for their very few front line pilots compared to the Germans who were trying to turn out several hundred pilots every month.
The Bf 109 always caused problems for novice pilots. I agree that a lack of training later in the war can't have helped, though many new pilots were being assigned to units operating the Fw 190 by then. This wasn't the case prior to the Focke-Wulf's entry into service across the Luftwaffe, which leaves almost half the war with no option for a combat fighter pilot but the Bf 109.
Cheers
Steve


----------



## cimmex (Jan 16, 2014)

stona said:


> I will repeat that I don't believe that the Bf 109, as it entered service with the Luftwaffe, would have been accepted by the RAF.
> 
> Cheers
> 
> Steve


Well, FAA, CAA, LBA accepted them nowadays


----------



## FLYBOYJ (Jan 16, 2014)

cimmex said:


> Well, FAA, CAA, LBA accepted them nowadays



Not quite - the FAA (and I would guess other aviation authorities) allow operation of wairbirds (like the -109) but they are not issued standard airworthiness certificates so the scope of their operation may be very narrowed (ex; day VFR, no passengers, if that was possible, and no operations over populated areas). There are features of WW2 warbirds that would never be allowed in production aircraft. In the US all non-type certificated warbirds are operated under either "experimental" or "restricted" catagory under FAR part 23.


----------



## GregP (Jan 16, 2014)

Most of ours (Planes of Fame) are experimental.


----------



## stona (Jan 16, 2014)

cimmex said:


> Well, FAA, CAA, LBA accepted them nowadays



Entirely different situation. There are not two or three hundred pilots a month coming out of flying school/OTUs and moving on to powerful, tail draggers, as front line fighters every month. The RAF went to great lengths to accurately assess the handling characteristic of all it's aircraft. Both the RAF's principle fighters had benign characteristics when compared with a contemporary Bf 109 and there is a reason for that.

Almost every veteran, including Luftwaffe pilots who had a chance to fly them, describes both the Spitfire and Hurricane as easy (childishly easy said one) to fly. You won't find many comments like that about the Bf 109. 

Nobody in their right mind is going to entrust one of the VERY few airworthy Bf 109s today to a novice pilot. Nobody has ever suggested that in the hands of an experienced pilot the type could not be mastered to become, at least in my opinion, one of the greatest of all piston engine fighters.

There was an old Luftwaffe joke that said when a Bf 109 and a Fw 190 crashed, Tank looked at the part that failed and made it stronger. Messerschmitt looked at the parts that had survived and made them lighter. 

Cheers

Steve


----------



## The Basket (Jan 16, 2014)

stona said:


> I willprobablythat I don't believe that the Bf 109, as it entered service with the Luftwaffe, would have been accepted by the RAF.
> 
> Cheers
> 
> Steve



RAF did run some ropey airplanes and the 109 was ok flying wise. If they had no spitfire they would have accepted 109 by the barrel full in 1940.
I read the MiG-15 wouldn't have been accepted. Ha. Prefer the death trap which is the Meteor. That had plenty of issues. Been inferior to the MiG was just one of them.
Seafire was hardly a steller. Anyway 109 had better stall than the Spitfire. British test pilots who flew the 109 had no probs with undercarriage but on takeoff rudder and tail hidden by wing so no control until tail lifts.
Have to feed power in slow. probably test pilot bravado. Remember 109 was a bantam fighter in its original guise so the undercarriage would have to get bigger and stronger as it grew. Probably not originally designed for the weights it carry


----------



## Balljoint (Jan 16, 2014)

I doubt that Willy had it in mind, but the Me-109 had two “counter” though probably not offsetting suspension geometry idiosyncrasies. The toe out would tend to steer the aircraft in the direction of the more heavily loaded wheel. This in itself is unstable in that such a direction change would then transfer weight to the other wheel and so forth. The technical term for this is “twitchy”. Cars have a bit of toe in for stability.
However, the 109 also has rather severe negative camber in that the top of the tire is tilted inboard of the bottom. This generates in offsetting camber thrust tending to turn the tire in the direction it tilts. Both wheels would offset each other when equally loaded. But a more heavily loaded tire turn in the opposite direction due to camber thrust than due to toe in.


----------



## Juha (Jan 16, 2014)

Lefa said:


> I have read, and although Finland used the plane until 1954, I have not read than one fatal accident, some broken machines, though. If anyone has information about the Bf 109 accidents in Finland, put the information here. Of course they are some, but I have not seen statistics
> I think a bad reputation came from Germany where late in the war, after very short pilot training, young pilots entered the plane.



Terve Lefa
Try to get Vesen's and Siiropää's Utin Koneet Siipi Maassa Utissa toimineiden lentojoukkojen onnettomuuksia ja vaurioita 1918-1963 (2008 ), t/o accidents to 109s were fairly common. So of the accidents and losses happened to the 109s operating from Utti, 21% happened during the t/os and 32% during landing and 15% during taxing. The %s for all a/c included into the book are 13%, 35% and 9%.

Juha

Reactions: Bacon Bacon:
1 | Like List reactions


----------



## GregP (Jan 16, 2014)

Hi Juha,

Hadn't heard the real numbers before, at least in Finnish service.

Thanks!


----------



## Milosh (Jan 16, 2014)

Some guy posted many years ago the accident rate for the Bf109 and Fw190A with JG26.

The results stuck with me over the years because the Fw190A had a worse accident rate (landing-take off) than the Bf109. Cant' remember the date he got his data from but iirc 1942-43 range.


----------



## GregP (Jan 16, 2014)

We have data out the yeng-yeng for US types and some British types. Any data, be it accident, operations, victories, losses, etc. for Axis aircraft or Russian aircraft in WWII is appreciated ... of course with some source quoted so we at least know where it came from.


----------



## gumbyk (Jan 16, 2014)

FLYBOYJ said:


> Not quite - the FAA (and I would guess other aviation authorities) allow operation of wairbirds (like the -109) but they are not issued standard airworthiness certificates so the scope of their operation may be very narrowed (ex; day VFR, no passengers, if that was possible, and no operations over populated areas). There are features of WW2 warbirds that would never be allowed in production aircraft. In the US all non-type certificated warbirds are operated under either "experimental" or "restricted" catagory under FAR part 23.


Here are the limitations that we have on our CJ-6. (WW2 aircraft will have much the same, or tighter, limitations.

Reactions: Like Like:
1 | Like List reactions


----------



## stona (Jan 17, 2014)

The Basket said:


> RAF did run some ropey airplanes and the 109 was ok flying wise. If they had no spitfire they would have accepted 109 by the barrel full in 1940.



But they didn't have to because they had the Spitfire and Hurricane and a back up plan.
Of course the Germans tested and assessed their aircraft to. My point is that there was a different ethos between the two air forces and this led to different perceptions of what could and could not be acceptable handling in their aircraft. 

If Britain had gone to war with France in 1939 and had no fighter of her own I'm sure she would have bought as many Bf 109s as the Germans could produce. It was arguably the best fighter in the world at that time.

Both the Spitfire and Hurricane entered service before the war. Various developments produced variants that had marginal handling characteristics. These were accepted as war time expedients but would never have been accepted during peace time. Examples might include the Seafire Mk III and certainly some PR Spitfires, overloaded with fuel.

Cheers

Steve


----------



## Lefa (Jan 17, 2014)

A little of topic.
This list covers the crew fatalities or significant damage to plane, or lead to the destruction of air accidents in Me-109 plane, but not in combat action destroyed planes, in Finnish Air Force.
Direct to the Google translator.

7/29/1943 MT -215 engine cut pesticide on a flight to catch , apparently without air combat injuries, the pistons, connecting rods came out of the engine and the engine coolant lit the entire aircraft . Staff Sergeant Instructor U.Lehto escaped by parachute

16 November 1943 MT -223

14 April 1944 MT -243

12 May 1944 MT- 236 and MT -242 collided at the start Suulajärvi . Run over the MP -236 's director , Lieutenant M.Salovaara died. http://sa-kuva.fi/static/17/05/131705_r500.jpg

18 May 1944 MT -418 was destroyed in Utti control error due to the rise. Lieutenant O.Lahti died. 

20 August 1944 Me- 109 was destroyed in the search engine on the way the Third Reich nightfighters training at a time when the instructor drove the machine into the woods in the dark. Ensign M.Tervo died.

27 September 1951 MT -460 damaged by falling in Kajaani , the propeller blade angle adjustment did not work due to low battery , which brought down the control error , combined with the machine on its back . The pilot , Lieutenant Kallio died.

The information here: Luettelo Suomen ilmavoimien lento-onnettomuuksista ? Wikipedia

I do not know if in that all, but only one what I found on the web.


----------



## Juha (Jan 17, 2014)

Hello Greg
the source material is rather heterogeneous, even the 109 material, the main part of our first Bf 109 unit, LeLv 34, operated at first from Utti, the material of the study are the accidents to the planes which operated from Utti 1918 – 63, little over 4 months in 1943 and then moved nearer to the coast to the Kymi a/f early in Aug. 1943. After that 109s that operated from Utti were almost all used to give a short 109 familiarization course to the pilots, either from training schools or from units which were converting to 109. And then there was the post-war use of 109s up to 1954, Utti was only one of the bases from where the 109s operated after the war. The absolute numbers for Utti based 109Gs accidents were: t/o 16, landing 24 and taxing 11 out of the total of 75.

Juha


----------



## GregP (Jan 17, 2014)

You know, we've had a few WWII fighters in civilian hands have taxi and takeoff acidents when they simply didn't see the plane in front of them. We had one P-51D do an overhead recovery (circular approach) and land right behind another P-51 and run right into him. It was fatal for both pilots.

Several taxied into carts, cars, or trucks. Not fatal, but certainly hard on the equipment.

At the Planes of Fame, we had one many-thousand hour airline pilot land our North American O-47 wheels up and it burned to the ground. We had another fly our pristine Grumman Hellcat into scud (low overcast) in Tennessee and hit power lines some 25 odd years back. Since them the mandate is that our old fighters only fly in severe clear. They stay on the ground if the weather is in any way threatening.

So the Bf 109's in Finnish service weren't the only WWII fighters who had taxi and landing accidents, but they may well have the highest percentage of these types of incidents.

Again, thanks for the info!


----------



## swampyankee (Jan 17, 2014)

As an aside, Stinton, in his book _Anatomy of an Airplane_ said that taildraggers should have toe-_out_, not toe-in for good ground handling. I have no personal knowledge of this, as my engineering experience was involved in keeping aircraft in the air, as opposed to landing.


----------



## GregP (Jan 17, 2014)

When building RC planes for 15+ years, once I switched to conventional gear I never went back to tricycle gear unless flying someone else's airplane.

In that time, I never one built in toe-out and mine took off and landed quite well. If I had an occasional hard landing and splayed the gear a bit causing toe-out, I bent it back or installed new gear. Never had ONE with bad manners except for almost all WWI models that have the gear way too far forward. The Spad XIII was the worst!

Once into retracts, the geometry was fairly well set except for toe-in / toe-out. Straight or toe-in was stable. Toe-out was squirrely.

I'm not talking about major toe here, only 0.5 - 1.5°. Mostly I tried to keep the gear straight. I only added toe if it displayed skittishness while taxiing at medium speed. It worked perfectly for 15+ years of good fun. I might start flying RC again since it seems unlikely I'll get to build the RV4 I want.

Let's say you land right wing low in calm air. If it has a bit of toe-in, the main gear tends to move very slightly to the left. Since the right wing is low, the natural tendency is to apply right rudder, moving the tail to the left and keeping the fuselage straight. It works VERY well.

But if anyone wants toe-out on his plane, try it by all means. If it works out, great. If I build a full-scale plane, I'll follow the plans, whatever they call for. If that happens to be toe-out, OK. If all the RV's flying around have toe-out, so will mine. They fly absolutely great!


----------



## cimmex (Jan 18, 2014)

It is really amazing how some people blame aircraft engineers who probably belonged to the best of the time that they were too dump to understand the basics of wheel dynamics when the decided that no toe out or toe in was the best for the 109 there surely were some reasons for this. Especially this kind of modification would not cost a lot so even Prof. Messerschmitt who is known as a very money saving man could not deny if necessary.
just my 2c
cimmex


----------



## The Basket (Jan 18, 2014)

A novice can crash anything.
ive seen a Mustang ground loop and Mustang had good wheels
Statistics prove absolute nothing. So 109 crashed. Because of its wheelscrashes ther? Bad luck? Novice pilot? Mechanical failure? Bad training? To compare 109 crashes and P-51 crashes is apples v concrete.
RAF would have accepted Bf 109. Sure of it. Whether the British industry would have designed a 109...dunno.


----------



## stona (Jan 18, 2014)

cimmex said:


> It is really amazing how some people blame aircraft engineers who probably belonged to the best of the time that they were too dump to understand the basics of wheel dynamics when the decided that no toe out or toe in was the best for the 109 there surely were some reasons for this. Especially this kind of modification would not cost a lot so even Prof. Messerschmitt who is known as a very money saving man could not deny if necessary.
> just my 2c
> cimmex



The reason for the geometry is supposed to be due to the transport requirements of the design laid out in 1933 (Taktische Forderungen fur das Jagdflugzeug (Land) ). One requirement was that the aircraft be small enough to be transported by rail. It was not a requirement as far as is known for the undercarriage to be attached to the fuselage (neither the Ar 80 nor the He 112 had this feature though the Fw 159 did) but this is what Messerschmitt decided to do. Once the undercarriage is attached to the fuselage, or more specifically a truss which also accepted the front attachment point of the wings and the lower attachment of the engine bearers, it HAS to splay out to be functional. Even splayed the track is still barely 2 metres. All the other problems stem from this. Altering the angle of toe or making other minor adjustments to the geommetry is like sticking an Elastoplast on an axe wound.

Prof. Messeschmitt may have been known as a money saving man, but don't forget it was two fatal crashes of the M20 transport and the subsequent refusal of Deutsche Luft Hansa to accept the type that led to the 1931 bankruptcy proceedings against BFW AG.
Later the **** up that was the Me 210, also designed by the illustrious professor, cost Messerschmitt AG an estimated 38,000,000 RM and led to Prof Messerschmitt's removal from the business side of the company.
He was certainly one of the very beat designers of his time, but when he did get it wrong it was very expensive indeed.

Cheers

Steve


----------



## swampyankee (Jan 18, 2014)

Milosh said:


> An aviation expert (??) by the name of Crumpp has stated that 'toe out' is better than 'toe in'.




Darrol Stinton, who was an aviation expert, reports the same thing.


----------



## GregP (Jan 19, 2014)

Probably in the tanslation Cimmex, but I didn't understand what you are saying.

We noted the high incidence of takeoff and landing accidents, the opinions of German pilots, and wondered why it wasn't corrected. Willy WAS a good engineer, but his Bf 109 landing gear surely could not prove that. The other main fighers had nowhere NEAR the ground accidents the Bf 109 did.

That says something about the design of the gerar and nothing about the Bf 109 once airborne. Once it was flying it was surely one of the best in the world at the time, even near the end of the war if flown by a competent veterant pilot. But the landing gear was abysmal compared with other top line fighters.


----------



## gumbyk (Jan 19, 2014)

swampyankee said:


> Darrol Stinton, who was an aviation expert, reports the same thing.


It depends on the aircraft, and the pilot.
We had one customer in a C-180 who continually had problems bouncing on landing. We rigged the undercarriage with toe-out. Because of the undercarriage type (spring steel), when weight came on the wheels, both wheels tracked outwards, and reduced the tendency of the spring steel to bounce the aircraft back into the air.


----------



## gjs238 (Jan 28, 2014)

stona said:


> Once the undercarriage is attached to the fuselage, or more specifically a truss which also accepted the front attachment point of the wings and the lower attachment of the engine bearers, it HAS to splay out to be functional. Even splayed the track is still barely 2 metres. All the other problems stem from this. Altering the angle of toe or making other minor adjustments to the geommetry is like sticking an Elastoplast on an axe wound.



How did the Grumman F4F Wildcat deal with this?


----------



## gumbyk (Jan 28, 2014)

gjs238 said:


> How did the Grumman F4F Wildcat deal with this?



Or any of the Cessna tail-wheel aircraft series? (or cub, maule, or any number of more modern tail-wheel aircraft?)


----------



## BiffF15 (Feb 14, 2014)

Okay gents I found an article from the summer 2001 issue of "Best of Flight Journal Fighters". That issue has an article called, "Flying the Bf109", by the late Mark Hanna and Capt. Eric Brown. On a post somewhere in here it was asked the source of the "information / rumor" of 109 accidents. This might be it (these excerpts are from the portion written by Capt. Eric Brown).

Here is a quote from page 54:

"The more than 33,000 Bf 109s produced from 1938 to 1945 gave the Luftwaffe an abundance of continuously updated air weapons. They were capable of beating their implacable enemies, even in the terrible conditions of Russia and North Africa. Many Luftwaffe Bf 109 pilots racked up scores in the hundreds that will dazzle the minds of air historians and fighter buffs for years to come.

But the Bf 109's deficiencies almost equal its fabulous assets. The Luftwaffe lost 11,000 of these thoroughbred fighting machines in takeoff and landing accidents, most of them at the end of the War when they needed them most. The inexcusably poor visibility from the cockpit greatly reduced their pilots' ability to fight. The snatching of the automatic wing slats not only caused many of the numerous ground accidents but also contibuted to a great many aerial accidents. The slat, canopy and landing-gear problems all had known simple production fixes. Perhaps Prof. WIlly Messerschmitt and the Luftwaffe generals were too busy patting themselves on their backs and counting Bf 109 victories to find time to listen to the pilots or to digest the significance of the Bf 109's accident rates.

The Bf 109 was, indeed, a prolific, necessary and timely fighter but was not as great as the Spitfire, the Mustang or the Hellcat, which all many fewer vices for the wartime pilots to overcome."

On page 51 he remarks about handling:

"From the handling viewpoint, the Bf 109E had two pluses and four minuses. On the credit side, it had a steep angle of climb that made it difficult to follow, and it could also bunt into a dive without its direct-injection engine cutting out under the negative G, thus leaving a pursuing British fighter behind as its carburetor-fed engine faltered. On the downside, the 109 had poor harmony of control: no rudder trimmer, which meant it was easy to inadvertently pick up skid and ruin one's sighting airm; in tight turns, the slats snatched open, giving lateral twitching and again ruining the pilot's aim. Finally, when the speed was allowed to build up rapidly in a dive, the elevators became increasingly heavy until at 440mph, they became virtually immovable."

Finally from page 53:

"Control harmony was poor because the rudder was light, the ailerons moderately light and the elevators extremely heavy. Control harmony in a fighter should be achieved with light ailerons, slightly heavier elevator and rudder heaviest."

I'm just the scribe and not the source...

Cheers,
Biff


----------



## GregP (Feb 14, 2014)

While I'm sure the Luftwaffe pilots got used to the elevator heaviness, it cannot have helped their agility at high speeds. Riggind a rudder trim is easy, so it's tough to understand the lack of it. I can understand no rudder trim in something like and Aeronca Champ or a Piper Cub, but not in a 1,000+ HP front line fighter.

All that does not detract from the incredible record of the Bf 109 in the slightest, but it could have been much better.

I am glad it wasn't!


----------



## tyrodtom (Feb 14, 2014)

Didn't the Bf109 have a airfoil shape built into the vertical stabilizer that provided some push toward the side. 

Not perfect, I'm sure. Not too effective in low speed, high power situations, like takeoff, and go arounds.


----------



## GregP (Feb 14, 2014)

Yes, it did. Unfortunately, it doesn't substitute for rudder trim.

It is possible the lack of rudder trim might have been exacerbated by the airfoil in the tail, but Willy Messerschmitt would have known that.

One of our older American fighters at the Planes of Fame is a Seversky AT-12 Guardsman. It only has 975 HP and has rudder trim. The newest American fighter we have without rudder trim, other than the Bf 109, is a Boeing P-26 Peashooter. It has a fixed rudder trim tab and is only about 550 HP. Ours is trimmed for cruise flight.

However, the Yak-3 also does not have rudder trim, but is not adversely affected by this. It does not have an asymmetric airfoil in the vertical tail.

So, the question would be whether or not the US - British pilots who flew these fighters for comparative tests were simply used to rudder trim while the Germans were not, and that made the difference in flight reports ... or whether the lack of rudder trim was really a big factor. Since fighters spent MOST of the time at cruise, and not in combat, I'd lean toward it being not much of a factor unless the combat dragged out for awhile.

But that is backseat quarterbacking from 80 years later, so I don't really know except that the few former Luftwaffe pilots we have had make presentations never mentioned the rudder trim in any of their talks. That doesn't mean it wasn't a factor, but also doesn't mean it was. All it means is they didn't talk about it at the time. Given the fact that they were addressing an American audience, it would not be surprising if aircraft faults were not mentioned even if present and remembered. They might talk about it among themselves, but saying it to an Americn audience might not ever happen. I can't say either way, and did not ask at the time.

I heard Saburo Sakai give a talk once at the old Champlin Fighter Museum on Falcon Field in Mesa, Arizona (back in about 1991 or so). He mentioned that the Japanese pilots envied the speed and climb of the Hellcats. He didn't say the Zero had shortcomings, but he did say he admired the Hellcat. Perhaps that is the same thing as saying the Zero was outclassed, but I would not put words into his mouth.

I also have never met anyone who had flown a Spitfire that has much bad to say about it, but we all know it had faults. It is probably natural to concentrate on the good things and ignore or minimize the bad ones when you are talking about a machine that you flew in a war or are flying now as a restoration / toy airplane.

Another thing I have mentioned before in here, we have had many Mustang pilots claim the P-51 was the best fighter in the world. I have asked maybe 3 of them what other fighters they flew in the war, and those three said they only flew the Mustang. I have serious doubts about someone who makes a claim gthat his mount was the best ... but never flew the others!

It is quite possible the german fighter pilots who flew the Bf 109 to such incredible victory totals never flew anything else. Not all, because we KNOW Erich Hartmann flew the Fw 190 when he wanted to do so, but stayed with the Bf 109. But many of the other Bf 109 pilots may not have flown any other German fighter or any captured American / British / Soviet fighter either, so maybe they simply didn't know the lack of a rudder trim was a handicap in the first place because that was all they knew about.


----------



## Gixxerman (Feb 14, 2014)

tyrodtom said:


> Didn't the Bf109 have a airfoil shape built into the vertical stabilizer that provided some push toward the side.



It did, I've seen the tail in profile from above it is definitely an asymmetric shape...but I can't understand why a simple trimming device wasn't used, if only to relieve pilots of the, er, 'leg-work' in normal flying and to make life easier for novice pilots.

The canopy I can understand as the best shape they could come up with at the time to extract the best aerodynamic performance but the undercarriage was so obviously an issue (given the huge casualty list) it beggars belief that they couldn't or wouldn't 'fix' it.


----------



## vikingBerserker (Feb 14, 2014)

Pretty interesting information fellas.


----------



## Denniss (Feb 14, 2014)

Is this value of 11k lost to accidents an estimation or backed by hard data?
The wing slats as major cause of accidents is new to me.


----------



## GregP (Feb 14, 2014)

Good question, Denniss,

I have seen that figure many times, but never with a quoted reference! I have head some Germans say many were lost to takeoff and landing but, again, no numbers .. and no references. So, like you, I wonder where that number came from.

I hope not from William Green!

Since your sig says you are from Germany, Denniss, do you know of a German reference where the number of Bf 109's lost in takeoff and landing accidents is shown? If so, have you seen the reference and do you recall the number? It would be nice to dispell the rumor or, at best, get some sort of accurate number with a good reference. Even for a partial time period, say ... something like 1941 - 1944, which would be representative of typical wartime losses even if not complete.

Of course, just a loss number without sorties flown also does nothing for us because we cannot the nfind the losses as a percentage of flights.

This gets worse as we work our way through it logically, huh? I'd expect the losses on the Russian Front to be worse than for the Western Front due to primitive forward airfields and operation from mud in the spring. But I don't know for sure.

Maybe some of our German friends DO know and HAVE references.


----------



## razor1uk (Feb 14, 2014)

The idea of wing slats causing problems might be more suggestive of allied opinions of the (enemies) automatic aerodynamic-pressure operated slats; though I would've thought that combat damaged slats could've aided in control issue problems leading to some slight additional percentage of loss than the rarer lesser chance of loss due to assymetrical opening/closing of them.


----------



## GregP (Feb 14, 2014)

Well, if one slat was combat damaged and would not open, and if the pilot didn't know it ... and if he pulled to hard at low altitude, it would snap-stall in the direction of the stuck slat.

I have not heard of that in combat reports I've read from either side. Additionally, most people shot at the canopy-engine area, not the wingtip.

So, in practice, I seriously dount it was a major factor, though ir certainly might have happened. I am under the impression that combat in the ETO was very much more high altitude than in other theaters, so maybe it happened and the pilot simply recovered and retreated to fight another day. If I had a major control issue with my plane at 20,000+ feet, I don't think I'd stick around to see if I could die that day.


----------



## razor1uk (Feb 14, 2014)

I too Greg, think it (the slats) were mostly insignificant in the problems that lead to losses, because they'd be more serious and dangerous other damage and problems than those from the slats on there own.


----------



## tyrodtom (Feb 14, 2014)

The slats are in sight of the pilot, if they're battle damaged he's very likely going to see it.

Wouldn't you think a pilot noticing damage around the slats, would check out their operation before he got low and slow.


----------



## razor1uk (Feb 14, 2014)

Why try to force them to deploy via an aggressive control action and risk the damage locking or causing more structural damage trying to get them to work for a test... surely if the wing in that area is damaged, you either try to escape towards safe lines and worry about low speed when coming to land or bail when it is safe to do so if you/they could see the damage was bad enough...


----------



## Milosh (Feb 14, 2014)

tyrodtom said:


> The slats are in sight of the pilot, if they're battle damaged he's very likely going to see it.
> 
> Wouldn't you think a pilot noticing damage around the slats, would check out their operation before he got low and slow.



He might not notice if there was any damage if the damage was internal like a piece of of something stuck in the track or if a small caliber bullet had bent a rod.


----------



## GregP (Feb 15, 2014)

I still say it was very probably a very minor part of accidents. Much worse would be one flap coming down but not the other one. You'd roll right in unless you were mighty quick to retract the down flap. That almost always happens at low atitude. Otherwise, you usually don't deploy flaps at all past a "combat" setting, which is very small deflection in all planes thaht HAVE a combat setting.


----------



## Milosh (Feb 15, 2014)

Once the pilot started winding down the flaps on the 109 he would know that one was not working properly.


----------



## GregP (Feb 15, 2014)

Yes ... if he encountered problems, he would reverse the process. It had better be quick since he's going to be low.


----------



## Aozora (Feb 15, 2014)

Speaking of the Bf 109 undercarriage; just got a book called Nest of Eagles. During a couple of test flights from Regensburg in late 1942 - early 1943 at least two test pilots discovered that only one leg was coming down while landing. Flugkapitän Trenkle bailed out, while Joseph Haid took a chance and landed. The cause of the undercarriage legs sticking was corrosion on the locking bolts.


----------



## GregP (Feb 16, 2014)

I can believe it. The uplocks are a bit unusual ... and seem like a design prone to failure ... but we haven't noticed that at all. Of course, our Hispano does NOT sit outside; it is in a hangar.

I do not know the frequency of Bf 109 uplock failures and have NO feel for whether it was an issue or not.


----------



## bobbysocks (Feb 16, 2014)

like everything else it should have had a time table for maintenance. if they knew or discovered it failed after X amout of hours/weeks/landings/etc. they would have serviced it prior to that and eliminated "most" of the problem.


----------

