You beat me to it Sam, I could only find the average speed of the Supermarine on the pylon course in '31, about 339mph.
OK, so I forgot about the silly Schneider races:
http://www.sciencemuseum.org.uk/on-line/flight/flight/s6b3.asp
Still, it would have been faster without the pontoons, which begs the Q:
Why didn’t the land racers simply adapt the S6B design? Even with underbelly radiators, the drag would have had to have been less than with those pontoons, and fuel could have been carried in the wings.
Probably because radial engines were dominant in US aircraft where seaplane racing was less popular. The extreme shape of the Gee Bee R1 and R2 were a result of trying to design a little airplane around an engine with a lot of frontal area. The bias toward radials continued through the fifties. There were exceptions like the P-40 and P-38 but the Allison engines in those planes didn’t match the Rolls Royce Merlin. The early version of the P-51 was a so-so performer and only came into its own when they switched to a license built Merlin in the B, C and D models.
Couldn’t hold much fuel in the wings though as they are very thin and the structures then weren’t well suited to wet wings anyway.
The Navy came up with a neat idea for landing planes on water. It is called a carrier! 
I’ve read (no cite) that the Schneider planes were seaplanes due to the lack of suitable (i.e., long & paved) runways. Doesn’t sound too unlikely to me…
Also because land races in the US were mostly short, closed courses around pylons in full view of crowds in grandstands, with tight turning rates at a premium (meaning short wingspans and light weight). The Schneider Trophy races were over longer courses where straight-line speed mattered more (meaning planes could use heavier water-cooled engines, as inline types are, if theit increased power made up for it.
A jet doesn’t inherently have a higher minimum landing speed than a prop plane - that depends mainly on wing loading (weight divided by area) and wing shape. There have been jet seaplanes, even fighters (including not only the Sea Dart but the Saunders-Roe Saro) but you don’t see any because there isn’t a good reason to do it.
I think the reason that seaplanes were the fastest is because they had truly massive engines in them, swinging huge propellors. It’s easy to build an airplane that sits up high on floats, but a lot harder to design one that sits up really high on landing gear. Pontoons are a big stable platform for a wild engine/airframe combination.
Not true at all Sam. The Supermarine S6B didn’t have such a big prop that it would have been difficult to use standard landing gear on it.
I guess you’re right. I was thinking they were much bigger.
I have a hard time seeing how that thing went 400 mph, even with 1900 horsepower. A Corsair wasn’t much faster than that, and it had 2000 HP and retractable gear. That Supermarine has gut rigging wires all over it, and a couple of big pontoons to haul around.
But I imagine it would be a lot lighter than a WWII fighter.
Lots of factors come into play. As big as those pontoons are the Supermarine has very little frontal area and is very light. It also has a thin wing section with a sharp leading edge. Look at the specs on the link I posted above, a tiny airplane compared to a WWII fighter bomber.
A corsair is a huge airplaine with lots of frontal area because of the radial engine. It’s also extremely heavy, much higher wing loading than a racer. The design is also different with a thicker wing with a rounder leading edge. The blade wings of the Supermarine would give unacceptable flight caracteristics for a carrier borne fighter/bomber.
A P-51 is a much better analog to the Supermarine. Low frontal area because of the long, narrow V-12 engine, a laminar flow airfoil, efficent cooling system (the scoop could actually add thrust in certain conditions) and less weight than a Corsair. The P-51’s forte was efficiency, the only fighter that could carry enough fuel to escort bombers to Berlin and back.
In air racing the top planes are a couple of P-51 mustangs and a Grumman Bearcat. Rare Bare has an engine twice the size of the Merlins and special prop with extra wide blades and it needs that just to keep up with the less powerful Strega and Dago Red.
Yeah, but Strega and Dago red aren’t exactly P-51 Mustangs any more. The engines make twice the horsepower, they are chopped down and streamlined, and in one case the wing of a Learjet replaced the Mustang wing.
Love the air races. My wife and I were engaged at the Reno air races. We’ve been there a couple of times since. I plan to go every year, but most years something seems to come up.
Some of you are calling them “pontoons”, they’re “floats”. I did an internship at a company that makes them. JRDelirious, in addition to the Twin Otter, I’ve seen floats on a Cessna Caravan and DeHavilland Turbo Beaver, both also turboprop powered.
The planes that raced for the Schneider Trophy were faster than land planes for a couple of reasons. It wasn’t well understood at the time, but the floats they used actually generated less drag than conventional fixed gear of the era. And since they had a long, flat surface to take off from, they could be designed for very high takeoff speeds; that meant high wing loading, short wingspan and very low drag. I seem to remember reading that the takeoff run was something like five to seven miles, but I haven’t been able to verify that.
Yes, the floats WERE more aerodynamic than the wheel landing gear - hence my earlier point about retractable landing gear.
Drag isn’t JUST about size (and certainly not about weight). It’s about shape. A wheel is a drag machine. It slows the airplane down. A “wheel pant”, which is usually just a fiberglass pod that covers the landing gear wheel in a fixed-gear plane, adds weight and size to the gear but also improves the streamlining and reduces drag - a properly designed and installed set of wheel pants can improve the airplane’s speed by around 5 mph for any given power setting and configuration.
Floats/pontoons/whatever you want to call 'em may, indeed, be heavier and large in size, but they are MUCH more streamlined than any fixed landing gear - they have to be, since they go through water which is a much denser fluid than air. It’s also fairly common for the struts attaching them to the fuselage to be a streamlined shape as well. The end result is that the floats generate much less drag than wheels.
Retractable landing gear generates even less drag than either floats or fixed gear. While retractable gear seems pretty obvious to us now, I’m not sure it was obvious in the beginning years of aviation. After all - how many other vehicles have retracting wheels? Once the idea occured to someone, the engineering details would then have to be worked out, which probably took some time. Until that happened, the float gear had a significant advantage over the fixed wheels.
Great thread, but I have one question:
Is Johnny L.A. out of town?
My point being that The big radials commonly had twice the displacement and stock horsepower of a Merlin but it didn’t make those planes faster. looking at the specs for Rare Bear and Strega they have nearly identical race weight but Rare Bear has several hundred horsepower more and that massive modified P-3 propellor. The equalizer seems to be aerodynamics.
I want to go to Reno too someday. I went to the first three years of the Phoenix air races but bad management killed it. This year is probably out but I think I’ll plan on seeing Reno in '04.
Say, which P-51 has a Learjet wing?
Broomstick, I beg to differ with your take on pontoon drag. Did y ou see the size of those bastards? Each one had more frontal area than the fuselage. They may have had a low C[sub]d[/sub] but that doesn’t make up for huge frontal area and induced drag from the large surface area. Faired struts and disk wheels or spats would have a fraction of the drag of the pontoons.
Broomstick: Miss Ashley II
Unfortunately, Miss Ashley II crashed at Reno in 1999.
And I don’t think I’ll buy lower drag for the floats vs landing gear. That Supermarine has flying wires sticking out all over the place, and a whole bunch of struts. Plus, those floats have a huge wetted area.
I might believe that they *could be less draggy than a completely unfaired landing gear and strut, but that’s now what we’re comparing to. The GeeBee and Hughes planes had gear that was faired out and very low drag.
Every land plane I know of that has been converted to floats loses speed in the process.
I think the reason the fastest planes might have been on floats might simply be because the Schneider Trophy attracted the biggest aeronautical talent.
I don’t think most modern jet planes could successfully be modified to land on water. As mentioned by several posters above if a jet engine ingests enough water spray it’ll go out. The design of most jet planes places the engine intakes low down, ideally placed for sucking up water.
If pontoon landing gear was added I think it would have to hold the aircraft so far off the water that it would be extremely hard to prevent it collapsing on takeoff or landing.
The Russian Ekranoplan from the cold war faced a similar problem. Its multiple jet engines were mounted right at the front and well clear of the water’s surface (follow the link for some pictures). The Beriev designs linked to by Bookkeeper show that those aircraft’s engines are also mounted high up with their intakes above the wings to shield them from spray as much as possible.
Here are some pictures of the Convair Sea Dart:
Here’s a great shot of it taking off.
Here are some static photos of a surviving sea dart. You can really see how the skis were designed.
First of all, WHICH floats are you refering to again? They don’t come one size fits all.
Second, surface area alone does not cause drag. My own body has considerably less surface area than the airplane I fly, but it has considerably more drag.
And when you’re talking about racers, the landing gear is just one factor among many. Features allowing for a longer take-off run but a faster flying speed also come into play
Yo, Sam - you know as well as I do that flying wires generate lots more drag than floats - or don’t you? Certainly flying wires generate more drag than struts. Which just gets into the many factors that go into designing an airplane, which involves trade-offs speed, drag, power, etc.
Right. And huge engines with huge frontal cross sections that partially cancelled out their low drag gear.
Size matters in aviation. The smaller the plane the smaller the float required and the less drag it generates. The absolute size of a float required goes up much faster as the airplane increases than the size of required wheels does. And you can’t compare modern landing gear drag to 1920-30’s era floats - you have to compare contemporary landing gear. In the era when seaplanes were dominant in speed the wheels used for land planes were often considerably different than today - much larger, for instance. Even with (oh heavens!) spokes like bicyle tires in the older models, which would have been drag monsters. The GeeBee was way ahead of it’s time in many ways and not a typical airplane of the era.
Sure, the dinky wheels on the C150’s I fly - particularly with their pants on - have less drag than a beaver’s floats. Stick tundra tires (I mean real tundra tires) on them and the C150 will slow down significantly (like it isn’t slow enough…) Given the unimproved state of many airfields pre-WWII the bigger, softer tires were needed. And distinct from a specialized racing plane (like the GeeBee) that would be carefully nurtured and cared for.
There was a time when the average seaplane was faster than the average landplane. It wasn’t a long period, but it existed. And it would make sense that, during that era, folks would race the planes perceived to be faster - the seaplanes.