Bf 109 squared canopy

[greybeard]

Hi all!
I always gave for granted Bf 109 squared canopy shape (at least from variant E-4) as peculiar of the type. Now I wonder why: I guess that would have been easy to follow curved shape of fuselage up to the windshield, making curved that as well. More or less as done with earlier variants, and even better like most contemporaries (e.g.: Spitfire, LaGG-3). Is by chance detailed in some official document why this choice? Thanks for any information.

 

[GregP]

Here's a Bf 109 with a radial engine and bubble canopy. So, we KNOW an alternate COULD be done. Bf 109V-21 to be exact, fitted with a BMW 139, a copy of a Wright radial.

Here an Ha-1112-M4L 2-seat trainer with a bubble canopy. So, again, we know it COULD be done.

Why wasn't it? Methinks wartime attrition was the culprit, with the Germans being loathe to interrupt production for a change. Similar to the US Navy not wanting to interrupt F6F Hellcat production to fit a non-dihedral wing to help the roll rate.

 

[nuuumannn]

I always gave for granted Bf 109 squared canopy shape (at least from variant E-4) as peculiar of the type. Now I wonder why: I guess that would have been easy to follow curved shape of fuselage up to the windshield, making curved that as well. More or less as done with earlier variants, and even better like most contemporaries (e.g.: Spitfire, LaGG-3). Is by chance detailed in some official document why this choice? Thanks for any information.

I can't offer a definitive answer as to why from any official sources, but the answer is obvious as soon as someone enters the cockpit. The Bf 109 was small, its fuselage was narrow and its cockpit was not very spacious. In the mid 1930s the Germans could not build blown canopies, so used flat panes of glass and plastic. The extra room is welcome, I've sat in the cockpit of a Buchon and it is small in there; folding the canopy closed there is very little room and the sill is at shoulder height; just below the rim of the canopy there isn't much space.

You can see how constrained the pilot is in this image...

DSC_8238

Here's the same aircraft's cockpit.

DSC_7789

The heavily framed windscreen of later model Bf 109s is evident here.

DSC_7794

Here's an interior shot of the RAF Museum's Bf 109G-2, which illustrates how cramped it is in there, especially with that central gun.

Motor cannon

As for redesigning the airframe to fit a bubble canopy via a cut down rear fuselage would have taken much production out of the lines and I guess the Germans didn't believe that the cockpit's small dimensions was too much of a hindrance to visibility; the Bf 109 proved to be more than capable of meeting any adversary on equal or superior terms in the early years of the war.

 

[Thumpalumpacus]

I can't offer a definitive answer as to why from any official sources, but the answer is obvious as soon as someone enters the cockpit. The Bf 109 was small, its fuselage was narrow and its cockpit was not very spacious. In the mid 1930s the Germans could not build blown canopies, so used flat panes of glass and plastic. The extra room is welcome, I've sat in the cockpit of a Buchon and it is small in there; folding the canopy closed there is very little room and the sill is at shoulder height; just below the rim of the canopy there isn't much space.

You can see how constrained the pilot is in this image...

View attachment 646351DSC_8238

Here's the same aircraft's cockpit.

View attachment 646352DSC_7789

The heavily framed windscreen of later model Bf 109s is evident here.

View attachment 646353DSC_7794

Here's an interior shot of the RAF Museum's Bf 109G-2, which illustrates how cramped it is in there, especially with that central gun.

View attachment 646354Motor cannon

As for redesigning the airframe to fit a bubble canopy via a cut down rear fuselage would have taken much production out of the lines and I guess the Germans didn't believe that the cockpit's small dimensions was too much of a hindrance to visibility; the Bf 109 proved to be more than capable of meeting any adversary on equal or superior terms in the early years of the war.

Did any idea of a Malcolm-style hood percolate into German designs? I've never seen any flying examples, but does anyone know if the Germans considered it?

Granted it wouldn't change much inside the 'pit, but wouldn't that at least increase outside visibility? Or was this a matter that the Germans couldn't, or did not want to, work with blown-perspex canopies?

 

[nuuumannn]

I dunno about 'Malcolm' style blown hoods, I'm sure our Bf 109 expurts here could confirm that, but obviously the Germans investigated the option in the image Greg posted above. I suspect it was that it didn't appear to be a hindrance to the type and that visibility, despite the cramped conditions for the pilots was considered acceptable. After all, the Bf 109 was the mount of the highest scoring aces in history, so it didn't affect their ability to do their job.

German pilots in the Luftwaffe put up with oddities peculiar to particular aircraft designs they operated, like the confines of the Bf 109's hood, the pop-top He 111 with its sliding hatch over the pilot so he could peer out while taxying since visibility was terrible on the ground and the Bf 110's engine instruments on the engines themselves - definitely an odd place to put them (I know why it was done, doesn't make it any less an odd idea), especially for a night fighter.

 

[pbehn]

Wasnt the main advantage of the Bf109 canopy in pilot exit? It was spring loaded so it sprung out of the way in a fraction of a second.

 

[nuuumannn]

Wasnt the main advantage of the Bf109 canopy in pilot exit? It was spring loaded so it sprung out of the way in a fraction of a second.

I dunno about that, I know that there was an emergency jettison lever in the cockpit, but in emergencies the procedure was to jettison the canopy by actuating the lever and pushing it away, with the air flow doing the rest, the obvious thing being for the occupant to duck when this happens.

You can see the lanyard taking the canopy's weight in this image. The lever on the canopy wasn't the emergency jettison lever, this one locks the canopy in place.

DSC_7793

The tensioned lanyard to stop it flopping over when open is clearly visible. In the manual it was advised not to taxi with the canopy open because it put too much strain on the two attachment points and they tended to wear out. Lubrication of the two points was part of routine servicing the aircraft.

DSC_5217

 

[GregP]

The canopy is very heavy for one-handed operation. The jettison device does NOT jettison the middle swinging canopy. It releases the rear piece of 3 pieces, into which the swinging piece is fitted with a hinge pin, and then the connected lanyard pulls the main canopy away is it departs the airframe.

The windscreen LOOKS like it blocks the view a lot but, from inside the canopy, it is not nearly as restricted as I suspected it would be. I've been inside an Ha.1112 Buchon, too, even upside down so I could attach the engine mount bearers in the extreme front of the cockpit floor. It was difficult to get out of once you were head-down inside, as you can imagine!

 

[nuuumannn]

The jettison device does NOT jettison the middle swinging canopy. It releases the rear piece of 3 pieces, into which the swinging piece is fitted with a hinge pin, and then the connected lanyard pulls the main canopy away is it departs the airframe.

That makes sense, Greg. The centre canopy has to be unlocked according to the flight manual and the pilot is advised to push on it to get rid of it. The main canopy is attached to the fuselage at its hinge points, so it has to be unlocked and jettisoned too, remember. It's not just the action of the rear section being unlocked, the mid section is done so also.

 

[GregP]

Actually, the main canopy is attached to the windscreen in front and to the rear canopy piece that gets jettisoned with pins. When the rear piece departs, the lanyard pulls the main canopy backwards with it.

 

[nuuumannn]

Actually, the main canopy is attached to the windscreen in front and to the rear canopy piece that gets jettisoned with pins.

The main canopy attachment points can be seen in the images. If you look at the image below, the locking pin, actuated by the handle on the canopy locks to the rear canopy. I don't have a view that shows it on the forward edge of the canopy. So, are you saying that when the jettison handle is pulled, the entire unit is pushed outwards - the manual stating the pilot has to push the canopy away from the aircraft? If this were the case, the lanyard would not serve the function of dragging the canopy with it unless the locking pin was undone when the jettison lever is pulled. The other issue I see with the rear section leaving the aircraft is the aerial, which in this image can be seen overlapping the edge of the rear canopy. does the aerial go too?

Canopy pin

 

[GrauGeist]

Messerschmitt was capable of providing a blown style canopy, as the Me163 shows, but for some reason, the majority of Messerschmitt's canopies were always framed.
The canopy system both on the Me309 and Me262, which was close to a "bubble canopy" design, allowed the pilot to sit high with excellent viability but the center section was framed including the swing access.

While I have never read a definitive explanation for this, I suspect that Messerschmitt wanted ease of production, as many other aspects of the Bf109s design reflected that ideology.

 

[GregP]

No. The main canopy pivots at the windscreen and the rear canopy. When you release the small rear canopy, it retracts a hook that keeps the top of the rear canopy in place. The main canopy rear pin is uncovered when the small rear canopy departs. It's how you get the main canopy off to work on it.

In flight, if you release the rear canopy, the lift air pressure will pull it out into the windstream and backwards along the fuselage. You don't care if it damages the fin because you are bailing out. The attachment chain takes the main canopy back with it as it departs the airframe. Simple and very effective. We've had the canopy off on the Ha.1112 many tens of times and it works quite well.

Seems complicated, but is actually very simple.

 

[nuuumannn]

Simple and very effective. We've had the canopy off on the Ha.1112 many tens of times and it works quite well.

Ok, I had my doubts about the rear section releasing when the jettison handle is pulled. I've looked through the Bf 109 manuals and can't see any mention of the details, all just stating the "canopy" or "kabine", not specifying which one. Having looked through my photos, the centre hood locking mechanism does lock into the front windscreen.

In flight, if you release the rear canopy, the lift air pressure will pull it out into the windstream and backwards along the fuselage.

Yup, found that in the manual, but the problem I see with the rear canopy coming off is the aerial. In the pictures above there is a fairing around it and it looks to be sitting on top of the canopy. Are you sure it is designed to be jettisoned when the centre canopy is? could it be that it comes off for maintenance?

 

[GregP]

The only way to get it off is to release the rear canopy. It goes back together rather easily, too.

 

[nuuumannn]

The only way to get it off is to release the rear canopy. It goes back together rather easily, too.

Thanks Greg.

 

[The Basket]

The Czechs develop a sliding hood so czech that out.

Seems a decent job.

 

[nuuumannn]

The Czechs develop a sliding hood so czech that out.

Seems a decent job.

The Czechs didn't think so, they didn't nickname it the Mule because of its utilitarian characteristics...

 

[The Basket]

This sliding hood I is talking about.