Re: Me 109 canopy with slot at the top?!
 

Boy, we're having a run with this one! In my opinion, David nailed it - it's for ventilation. Think of the greenhouse effect and imagine sitting in that small cockpit, suited with flying kit, on a hot/sunny day and add engine heat! To gain some air circulation and temperature relief, just slide the upper panel open; adjust it as desired with altitude and airspeed. The upper panel could also allow fumes/smoke to escape in an fire emergency. (A possible disadvantage is that the fire may then also “breath” and intensify.) Later models of the 109 with better closed-canopy ventilation, pressurization, or improved blown canopies eliminated the upper sliding panel. Any possibility a like panel was fitted to early Bf 110s (hinged canopy)? As noted, a/c with a progressive sliding canopy (e.g., Fw 190) would not need such a feature.

Re: Me 109 canopy with slot at the top?!
 

Im sure it was for ventilation. See the difference to the G-series.

E/F-series:
- light plexi glass canopy
- sliding panels (top, left, right)
- the side triangle windows on the "Windschutzaufbau" can be open

G-series (unpressured):
- heavy glass canopy for more protection
- only left and right sliding panels
- fixed glass on the "Windschutzaufbau" side windows
Additional for better ventilation to get the E/F-series fresh air conditions:
- the vent openings left and right on the fuselage in the cockpit
- the small airscoops below the "Windschutzaufbau"

Re: Me 109 canopy with slot at the top?!
 

This is going out on a limb, but what about gun gas venting? The F was the first model with a centerline cannon, and the F-1 carried the drum-fed MG-FF/M in a zippered canvas sack between the pilot's legs. I'd imagine things got a bit hazy in the cockpit after several rounds! The F-2 went to the MG151/15, and you'll note it was in a sealed metal enclosure from that model onwards. And don't forget the port windscreen quarterlight could be opened from inside, giving cross-ventilation... it's just a guess, mind you, but it seems logical.

Lynn

Re: Me 109 canopy with slot at the top?!
 

How much venting do you need?, the side slides open.... there must be a practicle reason for the top slider? Pilot exit in emergency???
K

Re: Me 109 canopy with slot at the top?!
 

If motivated by do or die, there's the possibility of attempted pilot egress through the open top panel, but even a small man would have to be a contortionist to wiggle through that hole, not to mention while wearing flight gear and rattled. Seems like a poorly executed escape route (if that was its purpose); it definitely wasn't for all sizes. Didn’t this canopy have an emergency jettison feature?

Re: Me 109 canopy with slot at the top?!
 

To see the panel slid open have a look at Prien/Rodeike "Messerschmitt Bf 109 F, G, & K Series", Page 18.
Maybe someone can provide a nice scan.

NoNo

Re: Me 109 canopy with slot at the top?!
 

Why would a slot be cut or even a plexiglass piece added, when there was a small tit/button for opening the side windows?

Re: Me 109 canopy with slot at the top?!
 

Here is the picture requested by NoNo of the panel slid open. It is from page 18 of "Messerschmitt Bf 109 F, G & K Series" by Jochen Prien & Peter Rodeike.

-Eric Zemper

Re: Me 109 canopy with slot at the top?!
 

There are several more photos of some F-1s, F-2s and F-4s (see pg 24) with the subject in question in the P&R book. On pg30, in the photo with Fw. Loddie, it looks like it was an added plexiglas piece.

Did the sliding glazing go under or over the rear piece of glazing?

Re: Me 109 canopy with slot at the top?!
 

It would appear that the front panel would slide over the rear panel.

Having seen the canopy of the 109 at our local museum, I think it highly unlikely that anyone would ever be able to exit the a/c through roughly half of the top panel.

Below is a crappy scan of a 109D-1 of 10.(N)/JG 26 taken in Stade in the fall of 1939, from Prien et al's, "Die Jagdfliegerverbande ..." Volume 2, page 224. It clearly shows the sliding panel in the top of the canopy, slightly open. This was apparently built into the night fighter version of that a/c to make it easier to see forward and upward when searching for British bombers at night. RAF tail gunners did the same with the rear panel of their turrets, to give them a slightly better view outside in searching for German night fighters.