If Reciprocating engines were still made (Read)

[wuzak]

Just thought I would do some comparisons.

Bristol Brabazon I
(Data from Bristol Brabazon - Wikipedia)
Crew: 6–12
Capacity: 100 passengers
Length: 177 ft (54.0 m)
Wingspan: 230 ft (70 m)
Height: 50 ft (15 m)
Empty weight: 145,100 lb (65,820 kg)
Max. takeoff weight: 290,000 lb (130,000 kg)
Fuel capacity 13,650 Imp gal (61,971 L)
Powerplant: 8 × Bristol Centaurus radial engines, 2,650 hp (1,860 kW) each
Propellers: paired contra-rotating Rotol, three wooden blades
Propeller diameter: 16 ft (4.9 m)

Performance
Maximum speed: 300 mph (260 kn, 480 km/h) at 25,000 ft
Cruise speed: 250 mph (220 kn, 400 km/h) at 25,000 ft
Range: 5,500 mi (4,800 nmi, 8,900 km) at 250 mph and 25,000 ft
Service ceiling: 25,000 ft (7,600 m) at full weight

Boeing 707-120 (first production variant, 1957)
(data from Boeing 707 - Wikipedia)
Crew: 3 minimum
Capacity: 174 passengers
Length: 145 ft 1 in (44.22 m)
Wingspan: 130 ft 10 in (39.88 m)
Height: 41 ft 8 in (12.70 m)
Empty weight: 127,500 lb (57,600 kg)
Max. takeoff weight: 257,340 lb (117,000kg)
Fuel capacity 17,330USgal (65,590 L)
Powerplant: 4 x Pratt & Whitney JT3D-3, 18,000 lbf (80 kN) thrust each

Performance
Cruise speed: 607 mph (977 km/h)
Range: 3,600 nmi (4,100 mi; 6,700 km)

The Brabazon uses 5% less fuel to go 1/3 further with less than 60% of the paying passengers at less than half the speed. While using more refined fuel.

Granted, the two are about 10 years apart in a period of rapid development, but it shows specific fuel consumption of one engine isn't everything economically.

New York to London is ~3,459 miles.

At cruise speed the 707 would cover that in ~5.7 hours, the Brabazon in ~13.8 hours.

 

[jetcal1]

At cruise speed the 707 would cover that in ~5.7 hours, the Brabazon in ~13.8 hours.[/QUOTE]

Which means utilization increases and revenue is doubled with reduced crew costs.
And, Jet-A was significantly (massively) less expensive which may have negated the fuel advantage of the Brabazon from an accounting point of view.
(Assuming they didn't have to capitalize a new fuel farm and logistics system. )

 

[PWR4360-59B]

Simple logic tells us if it is a prop test the other engines are only going to be running to take away any drag that they would cause if they where shut down, it would not be a fair test of the props ability if the normal engines where causing unnecessary drag. And what ever, its a prop plane that flew 1.2 mach.
It is old school if the date now is 2018 and not the mid 50's. I guess you don't understand what old school means.

Nice now with that Bristol Brabazon I, lets add CI engines of modern design as well as a modern airframe. Then the fuel can be the same as what the jet uses as well as the passenger load and less fuel too boot.

 

[jetcal1]

Nice now with that Bristol Brabazon I, lets add CI engines of modern design as well as a modern airframe. Then the fuel can be the same as what the jet uses as well as the passenger load and less fuel too boot.

Which still doesn't address one of the main reasons the airlines pitched the piston into the bin. The greater number of legs an airplane can fly in given time = more revenue for airline. More revenue means lower seat/pax/mile costs. Given the growth capacity inherent in moving from a United 377 carrying 38 pax in 1957 at $2,800 a head in constant dollars to a United 777 we are now boxed in to an economy class seat at $355. That would have been a $39.00 ticket in 1957 adjusted for inflation. If you want apples to apples, let's go first class! Todays $1,275 fare? $140.00 in 1957 dollars.

You just ain't gonna get there from here with a piston engine.The economies of time and payload are just not possible. (I won't get into the engine reliability issues. Nor will I mention how the reduced vibration of the turbine engine has also increased reliability of other components mounted in the airframe. (See mil-std-810)

Cheers!
JC1

 

[Shortround6]

Simple logic tells us if it is a prop test the other engines are only going to be running to take away any drag that they would cause if they where shut down, it would not be a fair test of the props ability if the normal engines where causing unnecessary drag. And what ever, its a prop plane that flew 1.2 mach.
It is old school if the date now is 2018 and not the mid 50's. I guess you don't understand what old school means.

Nice now with that Bristol Brabazon I, lets add CI engines of modern design as well as a modern airframe. Then the fuel can be the same as what the jet uses as well as the passenger load and less fuel too boot.

You simple logic is at odds with descriptions of how the tests were run. The logic also runs slam into the wall of the logic of how the hell The XF-88B with it's size and surface area was supposed to go anywhere near mach 1 on 2500hp which was all the engine in the nose would provide.
as to the "whatever" somehow I don't think most people would consider that speed in dive with the propeller feathered is any indication of how well the propeller worked at that speed in regards to propulsion. There was a lot more to propeller testing than just power in vs speed achieved.

Top speed achieved in level flight was mach 0.9 and that was with the afterburners running. Speeds of mach 1.01 (yes with the zero in there) were achieved in dives.

A modern airframe will show much improvement over the Barbazon but it will still get nowhere near the speed of a jet. The only prop plane that really did

used four 14,800hp engines for 200 passengers (6 abreast seating)
It had almost three times the power of the Barbazon. (ratio may be higher at cruising altitude).

A newer airframe may be better but it is going to have to fantastic in order to reduce the needed power by very much.
Slowing down would help a lot but even diesel engines of 30-40,000hp total are going to be large and heavy.

 

[DerAdlerIstGelandet]

Simple logic tells us if it is a prop test the other engines are only going to be running to take away any drag that they would cause if they where shut down, it would not be a fair test of the props ability if the normal engines where causing unnecessary drag. And what ever, its a prop plane that flew 1.2 mach.
It is old school if the date now is 2018 and not the mid 50's. I guess you don't understand what old school means.

Nice now with that Bristol Brabazon I, lets add CI engines of modern design as well as a modern airframe. Then the fuel can be the same as what the jet uses as well as the passenger load and less fuel too boot.

"Whatever its a prop plane...."

Go do some research, and come back. Until then, I'm not going to waste my time. I suggest the others do tge same.

I also suggest getting off your toy high horse. Your attitude is wearing thin.

 

[DerAdlerIstGelandet]

You simple logic is at odds with descriptions of how the tests were run. The logic also runs slam into the wall of the logic of how the hell The XF-88B with it's size and surface area was supposed to go anywhere near mach 1 on 2500hp which was all the engine in the nose would provide.
as to the "whatever" somehow I don't think most people would consider that speed in dive with the propeller feathered is any indication of how well the propeller worked at that speed in regards to propulsion. There was a lot more to propeller testing than just power in vs speed achieved.
View attachment 510702
Top speed achieved in level flight was mach 0.9 and that was with the afterburners running. Speeds of mach 1.01 (yes with the zero in there) were achieved in dives.

A modern airframe will show much improvement over the Barbazon but it will still get nowhere near the speed of a jet. The only prop plane that really did
View attachment 510703
used four 14,800hp engines for 200 passengers (6 abreast seating)
It had almost three times the power of the Barbazon. (ratio may be higher at cruising altitude).

A newer airframe may be better but it is going to have to fantastic in order to reduce the needed power by very much.
Slowing down would help a lot but even diesel engines of 30-40,000hp total are going to be large and heavy.

It's all in the links he provided.

He either:

1. Does not actually read them.
2. Does not understand what it actually says.

Don't waste your time.

 

[eljefe]

Yes you could up the cruising RPM but then you losing some of the advantage that the car/motorcycle enjoy. The ability to use high rpm to make lots of power when needed and the ability to cruise at a much lower rpm when only a fraction of the power is needed and use multi-speed transmissions to suit the engine speed (power band) to the task at hand.

A very important thing to note in a post full of good points. High power ratings in automotive engines are often produced under conditions that would drastically reduce the operating life of the engine (TBO) if sustained. By that, I mean that it only takes about 15-20 hp to move a typical passenger car at 60 mph on level ground. You'll also be shifting up to top gear to cruise at those speeds, probably at under 2000 rpm, in a motor that is capable of 300 hp at 6500 rpm. Now, imagine using that same engie to pull such a heavy load that you floor the accellerator pedal to maintain 60 mph...I'm pretty sure you won't make it to 100,000 miles without a major overhaul!

In aviation, you don't have the luxury of cruising along at 20 hp with the occasional brief romp at 200 hp to blip from 60 mph to 75 mph while impressing your passengers. You will be cruising along at a much higher percentage of maximum power, for hours at a time. This affects a lot of design parameters, and doesn't allow the sort of super high power/weight and power/displacement ratios found in racing automobiles...unless said aircraft engine is racing around pylons someplace.

 

[eljefe]

If they were wind milling it then there would be no need for an engine to power the prop.

If it was possible to drag a 12,000 lb airframe past Mach 1.0 with only 2500 hp, they'd have gone supersonic at Reno 20 years ago.

 

[gomwolf]

Pusher type(better thrust efficiency, and remove affection of prop wash, no need syncronized arms, and you can install radar on it's nose.), of course high power X type or coupled liquid cooling engine for it, counter rotating prop, glass fiber skin(for remove turbulence from skin), canard elevator, radar for arms.

Personal thought is larger and stronger version of Rutan Long-EZ with arms, retractable gears, high power engine and radar on it's nose.

 

[Ryanjames17]

A very important thing to note in a post full of good points. High power ratings in automotive engines are often produced under conditions that would drastically reduce the operating life of the engine (TBO) if sustained. By that, I mean that it only takes about 15-20 hp to move a typical passenger car at 60 mph on level ground. You'll also be shifting up to top gear to cruise at those speeds, probably at under 2000 rpm, in a motor that is capable of 300 hp at 6500 rpm. Now, imagine using that same engie to pull such a heavy load that you floor the accellerator pedal to maintain 60 mph...I'm pretty sure you won't make it to 100,000 miles without a major overhaul!

In aviation, you don't have the luxury of cruising along at 20 hp with the occasional brief romp at 200 hp to blip from 60 mph to 75 mph while impressing your passengers. You will be cruising along at a much higher percentage of maximum power, for hours at a time. This affects a lot of design parameters, and doesn't allow the sort of super high power/weight and power/displacement ratios found in racing automobiles...unless said aircraft engine is racing around pylons someplace.

Bought all I'm going to say to this is that.

The engine in my vehicle regularly sees, 40-80hp going down the road at 60mph, and it dose not have power loss threw a automatic.. 15-20hp going down the road could maybe be a small Toyota with a mannual transmission.. the best known automatic transmission as far as eating the least amount of HP still eats 15hp to turn it.

 

[PWR4360-59B]

So then out of all this nay saying here. You would all then agree that there has been no propeller powered plane, that is powered by just the propeller in level flight to ever exceed Mach 1.0 ? And no record of such thing ever happening? Is this correct?

 

[jetcal1]

So then out of all this nay saying here. You would all then agree that there has been no propeller powered plane, that is powered by just the propeller in level flight to ever exceed Mach 1.0 ? And no record of such thing ever happening? Is this correct?

Okay, I'll bite. There is no official recognition by the FAI of any aircraft solely propelled by a propeller that has ever exceeded Mach 0.9 in level flight

 

[PWR4360-59B]

Okay, good news, records are made to be broken.

 

[fliger747]

Speed is addictive! I was a 747 Captain for 15 years and flew every 747 except an SP, including the slinky new Intercontinental/Dash 8 and the Dreamlifter. These planes were flown every day for maybe 16 hours or more, day in, day out with an incredible reliability. Aside from the speed advantage jets have, the turbine reliability over pistons and the vibration reduction over turboprops. The last is important for both passenger comfort and airframe fatigue reduction.

I love the old props, where I live there are still DC6's and C46's operating in commercial freight operation. How nice to listen to four CB16's in a DC six rattle over the house heading North. But that's niche market. To be at all efficient the jets need to operate high, and for some like the 747 operate in a narrowly optimized speed window. A lot of the efficiency comes from staying in that window, optimum mach and optimum altitude for weight.

Maybe the pistons have more flexibility, as much as I love them (I own a small piston pounder) there are good reasons why the development of the piston for large aircraft has passed. General aviation could benefit from many modern developments in piston technology, but a small market and the certification process not attractive. Having been a Bush pilot at several points, the 1930's KISS technology does have advantages.

Cheers: T