Problems with early perspex canopies ?

[Jemiba]

When looking for material about the Supermarine Attacker, I noticed, that the
prototype and early variants were fitted with a one-piece canopy hood, whereas
the later types had a framed one, surely impairing view from the cockpit and maybe
increasing weight of the hood, too. Something similar can be said about the Republic
F-84 Thunderjet, I think and probably about some other types, too.
Anybody, who can tell me the reason for those modifications, that to me look like a
retrograde step ? Perhaps problems with large blown perspex parts ?

 

[Antonio]

I always thought the same about the F-84, why going to the later straight-wing variants when contemporary P-80 and F-86 had clean canopies?

 

[Jemiba]

Perhaps better resistence against bird strikes for aircraft, that were injtended to do more
flying hours at low level ? The later Attacker was a fighter bomber, too . ???

 

[Matej]

I think there is only one good reason to do so: strengthening the structure. Not only against birds, but also against enemy fire, flaks and such. If the material is strong enough, there is not any reason why not to make it as one piece. But the resistence is usually the better argument in military aircraft than a very good view around.

 

[Jemiba]

I think there is only one good reason to do so: strengthening the structure. ..

Thanks, Matej. Does it mean, that at least at this time (late '40s/early '50s) a single hit at
the canopy could have easily resulted in the disintegration of the complete canopy ?
I've seen plenty of photos of birdstrikes against modern jet canopies, which just resulted
in a punched hole, but then this is a result of better materials nowadays.

 

[Matej]

In general, you want to avoid as much schrapnels as possible to enter the aircraft/cockpit and injure the crew or damage the systems. Not only chaff schrapnels/birds, but also the pieces of the canopy itself. It is the big issue even today. For example Eurofighter, Rafale, Su-27 family or Sukhoi izdelije 54, they all have multiple pieces canopy simply because there were big concerns especially about the explosions of the grenades on the upper and front hemisphere of the aircraft. As you can see, there are a lot of civil planes with a big, single piece canopy with the nice view. It is strong enough to sustain the average collision with the bird, but it cant survive enemy fire. This is the difference.

As for now, the technology of the materials is matured enough to manufacture a very resistant single piece canopies for the fighters, however I think we will still see a lot of other planes (especially subsonic bombers and such) with a multiple pieces canopy because of its higher fight survivability.