Canopy Design

kool kitty89 · 05-02-2008, 02:54 PM

Besides visibility, what advantages and disadvantages do various canopy designs offer, and what effect on performance do they have. How does this apply to different a/c (particularly fighters), compared to their original canopies?

The ones I was most wondering about are:

P-47
P-51
Bf 109
Fw 190

Flyboy2 · 05-02-2008, 05:07 PM

I think the best type of canopy is the Malcolm hood. The bubble canopy has good visibility, but slightly less pilot protection compared to a "razorback" type. But the razorback had less visibility. The Malcolm hood had a good combination of both.

renrich · 05-02-2008, 05:27 PM

If you will notice, almost all post WW2 US fighters have bubble canopies whereas most Soviet fighters (after Mig 15,17) had a kind of razorback type design. There must be some drag factor working there. From my tiny experience flying an L39, one is strapped in so tight you can't turn around and look behind very far anyway. I have a friend who was an IP in Huns at the Fighter Weapons School(2000 hours in Huns) whom I asked about that. He said it was difficult to see much of the rear 180 degrees and he knew one hot pilot who in ACM disconnected most of his harness so he could utilise the bubble canopy.

kool kitty89 · 05-02-2008, 08:06 PM

I think it depends on the circumstances, and the speed operated.

THe argument Bill and soren got into was with the P-51, it turned out a study had shown pressure distribution and the teardrop bubble canopy resulted in less drag than the razorback/turtleback configuration, though the fact that the bubble canopy had a more sloped windscreen threw in a problem as well.

In the case of the P-47 the performance change is much more significant going from 435 down to 426 mph, the changes being the canopy and a gain in 500 lbs gross weight. (fuel capacity the same) The weight alone shouldn't have that much of an effect. (D-22 vs D-23) http://www.wwiiaircraftperformance.o...ical-chart.jpg

However it isn't clear if the figures were also due to addition of wing pylons, but since it lists fuel levels and ranges with 3x drop tanks for all models, this would be implied that wing racks were fitted. (plus racks were standard on the D-22 iirc)

In the Case of the P-47 the initial razorback canopy had less of a slope, but it also didn't have a flat windscreen, rather 2 pannels mounted at a rather sharp angle when viewed from above. Compared to the round slab screen of the bubbletop versions. (malcolm hood versions had the same configuration as the razorback save for the bulged frameless hood.

Of course there's also cases when fairing the canopy into the fusalage isn't the most practical, but a full bubble canopy isn't added either, even though the decking behind the cockpit closely resembles a bubble canopy shape.
Examples:

FLYBOYJ · 05-02-2008, 09:01 PM

Keep in mind that pilots in the late 1930s the technology to make Plexiglas with complex compound curves wasn't there. In other words bubble canopies. Look how the Zero compensated for that!

pbfoot · 05-02-2008, 09:54 PM

Quote:

Originally Posted by FLYBOYJ

Keep in mind that pilots in the late 1930s the technology to make Plexiglas with complex compound curves wasn't there. In other words bubble canopies. Look how the Zero compensated for that!

Was aware of the plexiglass issue but never put it all together in ref to the Zero canopy

Trebor · 05-02-2008, 10:24 PM

well, I like the bubble canopy. more visibilitymakes you feel more free. while the razorback kinda makes you feel confined, and part machine.

Glider · 05-02-2008, 11:35 PM

I have to admit that it mas my understanding that the Bubble canopy generally cost you a small decrease in spead but the additional visibility was a more than acceptable payback.
It also worth noting that a number of aircraft fitted with the teardrop canopy normally had to have an addition of some sort made to the tail, increasing the size, adding a piece to the base, whatever solution was chosen.

kool kitty89 · 05-03-2008, 01:28 AM

Yeah, the true bubble canopy would be a difficulty, but frames like the P-38 and P-39 (particularly XP-39) were close, Westlant Whirlwind, and to a lesser extent the Brewster Buffalo. And IMO the Nate/Oscar's canopy was better than the Zero's, smaller, simpler, cleaner and less framing.

But the Miles M.20 seems to be the first example of a full clearview teardrop canopy.

But before any of those, the Gladiator had something close and with relatively little framing, carried on to the F.5/39 design

Trebor · 05-03-2008, 02:25 AM

nice pictures, Kitty! I love the Zero! I do like the canopy of the Zero. it's kind of a combination of a bubble canopy and a razorback. and what I mean by that is the cage-like look the Zero canopy has. I like that. and that's one of the reasons why I like the BF-109

kool kitty89 · 05-03-2008, 02:48 AM

Oh if you want a real bubble canopy razorback shape cross-over how about this:

Trebor · 05-03-2008, 04:21 AM

ah yes, the Brewster Buffalo. that is a nice looking aircraft, but I prefer it to be in US pacific colors

(correct me if that's the wrong plane, please.

)

kool kitty89 · 05-03-2008, 04:58 AM

Well the Finns Brewsters came before the Buffalo name was given by the British, and either way the Finns never called their B-239's that. They were usually referred to as "brewsters" or sometimes Taivaan helmi ("Sky Pearl") or Pohjoisten taivaiden helmi ("Pearl of the Northern Skies").
(Other nicknames were Pylly-Valtteri ("Butt-Walter"), Amerikanrauta ("American hardware" or "American car") and Lentävä kaljapullo ("flying beer-bottle").)

But yeah it's a Brewster, but the US colors are kind of boring, though the the older symbols (meatball type) look good on it. (and it doen't look right with the spinner removed as was done to alot of F2A-3's)

This one's nice

And of course, the dazzel camo: The Art of McClelland Barclay in the Naval Art Collection.

renrich · 05-03-2008, 08:26 AM

The good thing about the Buffalo canopy was that one could have a green house and grow petunias back there.

drgondog · 05-04-2008, 01:20 PM

[quote=kool kitty89;350880]I think it depends on the circumstances, and the speed operated.

THe argument Bill and soren got into was with the P-51, it turned out a study had shown pressure distribution and the teardrop bubble canopy resulted in less drag than the razorback/turtleback configuration, though the fact that the bubble canopy had a more sloped windscreen threw in a problem as well.

In the case of the P-47 the performance change is much more significant going from 435 down to 426 mph, the changes being the canopy and a gain in 500 lbs gross weight. (fuel capacity the same) The weight alone shouldn't have that much of an effect. (D-22 vs D-23)

KK - the wing pylons of the 51 were smaller than the ones added to the late Model P-47D's and it made about a 10kt difference in the 51.

Added Weight would also decrease speed. That made the 51D slower than the B/C despite a slightly more powerful engine and what Lednicer proved for the bubble canopy, that it had a more efficient canopy (less drag). There was no such comparison for the P-47D so no conclusions could be drawn.

However it isn't clear if the figures were also due to addition of wing pylons, but since it lists fuel levels and ranges with 3x drop tanks for all models, this would be implied that wing racks were fitted. (plus racks were standard on the D-22 iirc)

I suspect the Pylons were a major factor as well as weight in reducing speed for similar fuel loads, requiring more Hp to achieve same or better speed.

QUOTE]

hard to make a case that 'bird cage' canopies are better design as far as drag is concerned.. been a long time since a high performance fighter has had anything but a tear drop type.