Just a couple of points:
1. No-one in this thread ever claimed that 110073 was definitely equipped with a pressurized Erla Haube. Piero suggested that it had received an Erla Haube at some point, to which I replied that if this was the case, it would be quite interesting, as this would need to have been a pressurized Erla Haube - which is not entirely inconceivable considering a pressurized Erla Haube was prototyped. That's all.
2. Of course, if the construction of the pressurized Erla Haube post-dates the May-July 1944 time frame (NOT 1943 as misquoted by harrison987) of the use of 110073 by 5.(F)/123, that machine obviously cannot have been equipped with it.
3. Modifying a regular unpressurized Erla Haube for cabin pressurization, as Graham Boak suggests, would not really be possible. The construction and materials of the regular Erla Haube are simply too flimsy to withstand the pressure differential. It would also have been difficult to accommodate the double canopy glazing required by the cold wall-type pressure cabin used by the G-5. The pressurized Erla Haube really required an almost entirely new design from an engineering point of view.
4. The date of 28 November 1944 as cited by Charles Bavarois for the letter to which the photographs of the the pressurized Erla Haube was attached poses an interesting question: what purpose did this work serve at that point, as by that time both pressurized versions of the K series and the H series had been long abandoned? Also, if these photos were part of a test report, the pressurized Erla Haube clearly must have existed before that date.
5. Harrison987's argument that "
Even the Me109K never had it in 44/45" is a non-sequitur: the only K version produced in series was the K-4; in addition, there may have been two K-2 airframes, and one K-6 converted from a K-4. All these machines lacked cabin pressurization, so why would they be equipped with a pressurized Erla Haube? The G-5 was the last pressurized 109 produced in series, with the final machines being delivered by Erla in June 1944. So, after that date, there was simply no longer any requirement to produce pressurized canopies of any type for the 109 - and obviously no need at all to equip unpressurized aircraft (i.e. all K machines constructed) with a canopy set up for pressurization.
6. Years ago, George Hopp posted on LEMB a document entitled "
Me 109H/ DB 628 Höhenjäger Kurzbeschreibung", dated 27 May 1943. You can download it here:
https://disk.yandex.com/i/F_uGWbCHbTW9GQ
Interestingly, in the description of the fuselage, it states "
Normaler Me 109 G 5 Rumpf mit Druckkabine ohne GM 1 Anlage, jedoch mit folgenden Änderungen: ... ohne Panzerscheibe, Kopfpanzer, Rückenpanzer, Leichtmetallrückenpanzer..." So, if I understand this correctly, this aircraft (likely referring to the V49, possibly V50) had a pressure cabin, but lacked the head armor. In the regular three-piece pressurized canopy, the head armor doubled as a pressure bulkhead, and was an integral part of the central hinged portion of the canopy. Hence, removal of the head armor in the standard three-piece pressurized canopy would have resulted in the loss of cabin pressurization. Yet, this aircraft is described as pressurized.
In summary, I am not at all arguing that 110073 definitely had a pressurized Erla Haube - in fact, as I've clearly indicated in my earlier posts in reply to piero, I think it is quite likely that the machine had a standard three-piece pressure canopy during its entire existence. However, I do feel, that, on balance, the possibility that this experimental aircraft at some point might have received a pressurized Erla Haube cannot be entirely discounted. Hopefully, the photos mentioned by David Wadman al those years ago will one day show up!
Many thanks to Nick Beale and Charles Bavarois for providing the transcripts, and for further information regarding the pressurized Erla Haube!