So all those planes were faster 75 years ago than what we can do today (propeller driven)?
As I said, aircraft are compromises. The F6F Hellcat, for example, was speedy. But it also had a 2,000 horsepower engine. I don’t know how many GPH it burned, but it was a lot. Carrying a single person. That wouldn’t work for small passenger aircraft. On the other hand, small passenger aircraft can’t maneuver like a Hellcat.
There’s the modern day Otto Celera 500L. 460 mph cruise speed on 550 hp.
Looks slippery.
It looks like it would require the landing speed of an F-104. There’s no free lunch.
But imagine a fighter version in WW-II that replaces passengers with ammunition.
Indeed. Speed, payload, economy. Pick two.
Well, there was the Ass-Ender… sorry, Ascender that could do 390 mph (on 1,250 hp).
Yes, that’s the one that crashed in my area during an airshow in 1945. Actually the same location of the modern day Air Force Museum. It turned a car it hit into a fireball and a baby was saved by throwing it out the window.
The purpose of a modern prop plane is different from a WWII fighter. Props become more inefficient at high speed, so there’s no point using them. In WWII, there were no other options, so if you wanted to be fast you just went as fast as a prop engine could take you, regardless of inefficiencies. Once jet engines became viable, they changed to using jets, which are far more efficient at high speed than props.
Getting a propeller plane to go over 500 mph is extremely challenging. The fastest racers at the Reno Air Races start out as WWII fighters, then they have their horsepower massively increased (more than doubled), their wings clipped, canopies cut down, anything draggy removed, sometimes entire new wings are put on them, etc.
These planes can crack 500 mph in a staight line at Reno’s altitude, but more regularly fly the course between 450 and 480, Their engines last maybe an hour before needing to be overhauled.
I think that have this right (but maybe not) - it requires 4x the power to double the speed. In a piston engine, the weight increase needed to get increased power has practical limits. You end up with a flying engine and not much else. Add propeller-related limits and trying to get more speed becomes fools errand.
Did anyone watch the PBS show on the Hindenburg? It had a lot of information on the subject I hadn’t heard before.
The fastest planes in the '20s and '30s competed for the Schneider Trophy, and they were seaplanes. In order to reach the highest speed, the planes were designed for very high wing loading and takeoff speeds. I seem to remember that it took several miles to get airborne, so the best option was to take off from water.
that would explain why they were sea planes but wow, high speeds on water would make takeoff and landings really dangerous.
For pics, inside and out: https://www.ottoaviation.com/celera-500l
Hmm, I don’t know if a seaplane would be any more dangerous than a land plane in comparable use. If the weather is bad on a given day, they could just postpone the race until tomorrow. And if they’ve got a large enough stretch of water, they could take off and land directly into the wind. If you had the best trained pilots, and only operated in perfect conditions, I don’t how dangerous it would be.
Hold on to your money. That thing isn’t going to go anywhere near that fast, be that cheap to operate, or have anywhere near that range.
The notion that you can fly a 550 hp, twin turbocharged, pressurized airplane for $328/hr in commercial service is ridiculous. My giess is that number is just for fuel and maybe engine time. This is less than a single engine piper Malibu with about half the horsepower. Add in scheduled and unscheduled maintenance, amortized cost of the plane, insurance, hangar/pad space and all the rest like we do when calculating operating cost, and this thing won’t be any cheaper to fly than other equivalent planes other than somewhat lower fuel burn per mile.
The engine is the most efficient part of the thing, IMO. It’s a diesel engine burning jet fuel, separated into two independent sections for safety, and its fuel efficiency is .35 lbs per horsepower-hour. So at a 75% cruise, I get about 20 gph. Jet fuel is about $4.75/gallon, so just the fuel cost will be close to $100/hr.
That’s pretty good, but the Celera needs to fly really high to get anywhere near the numbers they are quoting (>50,000 ft as a guess), and the Red engine has a critical altitude of 25,000 ft.
I suspect their numbers are given perfect prop efficiency, laminar flow across the entire fuselage, super-high cruising at high power, optimistic estimates for cooling drag, intersection drag, etc. Wait until a production model comes along with access panels, passenger windows, radio antennas, etc. Maintaining high laminar flow will be challenging.
As a comparison, the Lear Fan is a similar pusher prop, laminar flow airplane:
That thing used two coupled PT-6 turboprop engines making a combined 1300 hp, and had a maximum speed of 450 mph. But it only cruised at 320. So the Celera 500 is supposed to cruise 140 mph faster on less than half the horsepower. I’ll believe it when I see it.
Also, I predict handling problems. Trying to maintain laminar flow in front of a pusher prop seems like a recipe for asymmetric flow detachment playing havoc with the prop. Designers generally don’t go for maximum laminar flow because A) it’s really hard to maintain in the real world of dirty airplanes with production compromises built in, and B) when laminar flow detaches and becomes turbulent it can do so quickly and forcefully, leading to dangerous handling problems.
I predict that if this thing ever makes it to production, the final version will cruise at more like 300 kts at 35,000 ft, 250 kts down around 20,000, and have more like a 2500nm range. Those would still be good numbers, but not the kind of ‘disruptive’ numbers that attract big investors with lots of money but little understanding of aviation.
the higher the landing speed the greater the hazard. And the difference between landing on water and land is the land is not constantly moving. Water landing is considered another skill in addition to hard surface landings even though, technically, you could probably get just a sea rating.
In real-world, day-to-day flying, what you say is true. But I assume that air racers back in the '30s could wait for conditions to be just right. If smooth water is the safest for takeoff and landing, then the pilots and crews get up early and check. If the waves are too high, they call it off and set their alarms for the next morning.
I do know a bit about seaplane flying; I did an internship with a company that makes floats. I remember hearing somewhere that glassy smooth water isn’t the best for taking off. If you want to fly from a lake and the water is too flat, you can taxi around a bit to generate some waves, and then take off.
The Dash 8 Q400 cruises at 360 knots, which Google tells me is about 414 mph. That is fast for a passenger turboprop. But from what I understand it also gets poor fuel economy for a turboprop (but better fuel economy than a similar sized jet).
I don’t think this is correct. Schneider specifically wanted seaplane races because he thought amphibious planes were the future and that their development wasn’t proceeding as fast as land planes. It had nothing to do with stall speed or takeoff distance. In fact, one of the most successful Schneider cup planes was a Supermarine seaplane (S6B) that was a precursor of the Spitfire, and it had a normal stall speed for aircraft of the time.
Any extra takeoff distance was probably the result of the floats themselves.
Here’s a list of all the Schneider cup aircraft:
I looked at a few and didn’t see anything abnormal about their wing loading or anything else that would make them hard to take off on land.
Here’s a cool archive of Schneider Cup race commentary:
https://www.thisdayinaviation.com/tag/schneider-cup-race/
Here’s the comment about takeoff: