From my research it seems most all WW II fighter ac made the switch from ‘Razorback’ to ‘Bubbletop’. The obvious reason was visibility; but little mention is made of the process developed/used to make the transition.
The first improvements seems to have been in the ‘Malcolm’ canopy derived for the Spitfire VIII and the P-51B/C in 1943.
Just thought I’d ask if any one had any info![banghead]
Not sure I understand your question. Are you asking about the engineering/design process that led to the new airframes? All of the aircraft development during the war years concentrated on improving performance of existing airframes, improving the odds for pilot surviveability, and developing new more pwerful aircraft with better weapons. For example, the P-51D has many more differences with the B/C models than just the cut down rear fuselage spine & bubble canopy. Same for the P-47D Bubbletop & Razorback models. BTW, some Razorbacks were also equipped with the Malcom Hood style canopy. The full answer is way beyond inclusion in a post, but references such as the " Detail in Scale " series give a pretty fair description of the differences between the various versions.
Regards, Rick
What I thought I said and what came out were basically the same thing. However, my thoughts didn’t totally convey the intent.
What I was looking for was the process of forming ‘bubble’ canopies and considering the aerodynamics of flight, why was it not done previously?
What was the comparison between the safety (bullet protection) of each?
I know that the switch wasn’t made for aerodynamics. For example, when the P-47 was changed to a bubbletop, it lost alot of stability due to the loss of surface area behind the cockpit. That’s why you see later P-47’s with the dorsal fin.
Aerodynamically, a bubbletop canopy would have more drag than an razorback too. Though, if designed correctly, the bubbletop shouldn’t provide to big a loss. It is usually designed with a “tear-drop” shape so the drag is lessened. The gently tapering shape of the back of the canopy creates a lower drag coefficient. If it had of been a different shape (with the front of the canopy the same shape), and a sharp change of shape at the back, the drag would be increased.
Mostly the change was made to improve pilots visibility. There was a big blind spot right behind the pilot in a razzorback plane. Protection wise, There was a large armor-plated head rest behind the pilot on the P-47. There would of course be less protection, but not much less.
Don’t know why they didn’t change earlier to bubbletop. It might be because they didn’t have the ability to form the canopy. Someone else will be able to tell you.
Hope you can make enough sense out of this to make it helpful.
Not to mention all that canopy framing getting in the way of your line of sight as well…if you have ever flown a flight sim (I know- not the real thing, but not many here fly the real thing)-- the difference in trying to dogfight in a 51B or a -D is quite noticeable…you don’t realize how thick that framing is until you try keeping an enemy plane in sight.
Jeeves hit it on the head… big difference in visability. I’ve sat in a P-51D and I can only imagine how difficult the vis was on others. I imagine it’s the same with the P-47 Bubbletop.
Thanks for confiming my suspecions on the visibility issue. In every movie you’ve got the pilot with his head on a swivel tryin’ to look out/over the framing.
The other part of the question was about the process of canopy forming and how much of the ‘bullet proof’ consistancy varied between types.
Just one of many questions that pop up.[?]
Transition to the bubbletop according to a documentary I saw on Discovery Wings was primarily facilitated by a wartime advancement in plexiglass manufacturing technology. Same advancement facilitated the larger and less obstructed views on the bombadier noses seen from the B-17E variants on.
The drag effect was another issue as earlier stated, but they picked up on that pretty quick by extending the dorsal fin. Similar issue as you can see with the extension of the dorsal fin as of the B-17E models I’ve been told by an aeronautical engineering buddy off my father.
Judging by a quick websearch, I would assume that the timing was due in part to advances in processing technology.
Poly(methyl methacrylate) (PMMA, commonly known as plexiglas) was developed in the mid 1930’s, so I’m guessing that this was the material used for canopies during WWII. As with any new technology, there are always obstacles to be overcome, including:
Methods of fabrication still need to be developed. Creating flat sheets is one thing, but getting the molding conditions is another.
Ability to incorporate into the design. I’m guessing that many of the planes were at least on the drawing board in some form before bubbletops were really an option; some reconfiguration of the designs had to be made.
2a. Intellectual inertia. Within a lot of engineering environments, there’s a lot of “this is how it’s been done in the past, so this is how it’s going to be done in the future.” Part of it is a product of the education system, and part of it comes from corporate environment.
In this case, I think it was due to education, because if you look at the initial designs of the Spitfire, P-51, Corsair, Wildcat, P-47, and Me-109, all of them have a rear bulkhead/“tall” dorsal area. But you do have to wonder when exactly did the engineers find out about the material.
But these are just conjecture. As to specifically what advances were made in these areas and when they occurred, and why they were only only applied to certain designs (P-47, P-51) while not to others (Corsair, Wildcat), I don’t know.
One other note - the canopies on the F-16 are made from polycarbonate (aka Lexan, also happens to be the same material CDs are made of), but this material wasn’t developed until the '50’s.
Thank you for answering my question(s) in both great and satisfactory detail. This is another great reason to join the Forum![bow][bow][bow]