Dumb Question about Big A$$ Aircraft Piston Engines

Tantalum

Tantalum

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Got caught up watching a documentary on the BF109 (link if anyone cares).. so why did we not put bigger piston engines on original GA planes?

BF109 - 1,455 hp
Spitfire - 1,470 hp
P51 - 1,490 hp

The first few personal GA planes in the 1940s and 1950s could easily have used some of the bigger more powerful piston tech available that was developed for the military, however they elected to go with itty bitty engines and very slow cruise speeds with anemic performance..

How bad ass would an original V-tail Bo (which was instroduced in 1947 for pete's sakes!) have been with a 1,400 hp V12.. so what gives? Why did the original aircraft manufacturers sell themselves short on performance? Even if you don't need *that* much power, surely we didn't have to handicap ourselves creating a situation where no real GA plane can actually fill its tanks and seats.. ?

"hey Jim, doesn't your plane have 6 seats?" "Yeah Bobby, but I have to put fuel in it too, so bad news but only you and me can go" <- the Bo has a useful load of 1,100 lbs.. throw 80 gallons of Avgas in there and you're literally left with two (maybe 3) big dudes and their luggage plus 4 empty seats... wtf?!

Educate me.
 
maybe there's an STC for one of those bad boys
 
Divide the HP by about 14 and get an idea of the fuel burn in gallons per hour at full power. What would the market be for a 1200-hp light airplane? Shoot, there were surplus fighters being sold off cheap after the war; the few that were sold were often cannibalized for stuff to make farm equipment. Nobody could afford 100 GPH for a fighter. Most could barely afford 7 or 8 GPH. Even the T-6 ate up a lot of fuel with its 450-hp engine.

Besides that, these high-powered things were way beyond the skills of the average PPL. Things happen fast with that much power and speed.

TBOs were terribly short, too.
 
Dimensions, weight and fuel burn...and cost.
 
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midwestpa24 said:
Ever paid the fuel bill for a Mustang? How about overhaul on a V-12? That's why
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Fair.. but my understanding is that a PT6 is not a cheap engine to feed and maintain either.. just wondering why not a single GA manufacturer "back then" elected to do something more TBM / PC12-esq with the original tech.. the PT6 wouldn't come around for another decade or two..

It seems like we immediately limited ourselves to 300-ish horsepower at the upper end
 
And those big engines were rebuilt/replaced every 200 hours or so. (In military usage). They are impressive power plants for sure but not very practical. Now the piston engines (usually radial) used in some of the last generation piston airliners (Connie, DC-6) were longer lived but still an great deal of fuel and oil required.
 
There's a local group restoring a Corsair at my home field. Though it's not for the plane, they have an R-4360 Wasp Major (that's P&W's 28 cylinder corncob radial) on a trailer; they bring it to airshows and run it up to attract attention (donations). It costs them about $1000 just to start it up.
 
midwestpa24 said:
Ever paid the fuel bill for a Mustang? How about overhaul on a V-12? That's why.
Click to expand...
Weight,, An Alison V1710 weighs well over a thousand pounds.
P&W 985 weighs 650 pounds. @ 450 horses.
 
Tantalum said:
The first few personal GA planes in the 1940s and 1950s could easily have used some of the bigger more powerful piston tech available
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The one thing you forget there was a ton of surplus military aircraft floating around with those big motors that "sold" for a song. No need to cram one in a brand new civilized flying cruiser. From what I was told, one could buy a brand new 140 to fetch the groceries and also keep a nice P-40B parked on the ramp when there was a "need for speed." It was definitely a different time from '46 to to about '54... at least from the stories I heard.
 
Those airplanes are big even though they are single engine, they are thirsty too.
 
If you are an airplane designer, and you are tasked with carrying payloads consisting of several heavy belt fed machine guns, even heavier ammo, and maybe some bombs, and give it minimum performance requirements necessary for aerial combat; you end up with something that looks a lot like a P51 Mustang.

On the other hand, if the objective is to take the girlfriend for a couple hour trip to get a burger and still have money left over for some drinks, a nice dinner, and perhaps another girlfriend after this one dumps you, it will look a lot like a 152.
 
Tantalum said:
The first few personal GA planes in the 1940s and 1950s could easily have used some of the bigger more powerful piston tech available that was developed for the military, however they elected to go with itty bitty engines and very slow cruise speeds with anemic performance..
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As Tom pointed out, those powerful engines are big and heavy. That is going to drive a big and heavy airframe that burns a lot of fuel while it goes fast. After the war, most people probably had the wherewithal to buy and operate a Cub or Aeronca. Some people had the finances to buy a Bonanza, Navion, or C-195. A smaller number had the ability to buy and operate a Beech 18. An even smaller number could afford a DC-3. But the number of people who could afford a real go-fast machine was pretty small. Sure, there were a few Lockheed Lodestars, B-25's, and B-26's converted for executive use after the war, but that represented a <relatively> small number of airframes, and the surplus aircraft (i.e. the starting point for a conversions) were relatively cheap.

There just wasn't enough of a market for a 300 mph, 6 seat airplane the size of a Grumman Avenger and powered by an R-2800 to justify the development cost.
 
Bell206 said:
The one thing you forget there was a ton of surplus military aircraft floating around with those big motors that "sold" for a song. No need to cram one in a brand new civilized flying cruiser. From what I was told, one could buy a brand new 140 to fetch the groceries and also keep a nice P-40B parked on the ramp when there was a "need for speed." It was definitely a different time from '46 to to about '54... at least from the stories I heard.
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In one of my aviation books I have a aerial picture of a row of P-51 Mustangs on a Royal Canadian Air Force ramp. When the RCAF discontinued using them as fighter lead in trainers they sold off hundreds of them for $500 each and included a spare engine. None were allowed to stay in Canada, so most went to Latin American air forces or to private USA purchasers. I think a bunch of them ended up at Cavalier.

Note for @Tantalum: Cavalier was a Florida company that through the 1960s completely stripped military P-51s and rebuilt them as "Executive Mustangs" with dual seats, leather interiors, luggage bays and new paint. Go fast personal transport. Sort of a TBM of the day, without the hassle of carrying more than one passenger. :)

Decades ago at Reno I was wandering around the ramp and race pits (it was a different scene then), someone landed and taxied up in a Cavalier Mustang. Hopped out and opened what used to be the ammunition locker on one wing and pulled out a lawn chair. Went over the other wing locker and pulled out an ice chest. Motioned us over and handed us each a cold beer. Went on to tell us he owned the world's most expensive beer cooler. He lived in SoCal and said the time it took him to get to altitude and over the Sierras was just enough to cool the beer to the right temperature.
 
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Sac Arrow said:
If you are an airplane designer, and you are tasked with carrying payloads consisting of several heavy belt fed machine guns, even heavier ammo, and maybe some bombs, and give it minimum performance requirements necessary for aerial combat; you end up with something that looks a lot like a P51 Mustang.

On the other hand, if the objective is to take the girlfriend for a couple hour trip to get a burger and still have money left over for some drinks, a nice dinner, and perhaps another girlfriend after this one dumps you, it will look a lot like a 152.
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There's the Taxpayer's Airplanes. And then there's the taxpayer's airplane. ;)
 
Tantalum said:
...How bad ass would an original V-tail Bo (which was instroduced in 1947 for pete's sakes!) have been with a 1,400 hp V12...

...Educate me.
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I got 12 cylinders. And most people here ***** about how much fuel those piston twins (that they don't own) use.

Ya just can't keep this crowd happy...:rolleyes:
 
War effort design method:
1) Acquire the biggest engine available.
2) Design an aircraft around it that will carry enough armament to go up against the enemy's aircraft at a speed higher than.
3) If possible squeeze in a bit of armor around the pilot.
4) When in doubt, ignore the cost, there's a war on.

Buddy of mine talked about being a line boy at Vegas back in the fifties, businessman there had been a fighter pilot during the big one. Kept a nice shiny P51 (as has been previously mentioned) for business trips. One day when everything on the tiedowns was trying to fly away he nonchalantly launched that heavy iron like coming off a carrier into a gentle breeze and disappeared towards California. Great story I thought.
 
Dana said:
There's a local group restoring a Corsair at my home field. Though it's not for the plane, they have an R-4360 Wasp Major (that's P&W's 28 cylinder corncob radial) on a trailer; they bring it to airshows and run it up to attract attention (donations). It costs them about $1000 just to start it up.
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Why would it cost $1000 to start up?
 
Mtns2Skies said:
Why would it cost $1000 to start up?
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My guess... an engine like that will burn a lot of gas, burn a lot of oil, need to be overhauled pretty often, and break a lot of very expensive parts. Just a guess.
 
Awfully hard to land the heavy, rip-snorting beast on the field behind grandpa's barn.

Post WWII most airports were shorter, often grass strips.
Only the military and airlines had a mile of smooth pavement.
 
Non Compos Mentis said:
Awfully hard to land the heavy, rip-snorting beast on the field behind grandpa's barn.

Post WWII most airports were shorter, often grass strips.
Only the military and airlines had a mile of smooth pavement.
Click to expand...

But fighters across the Pacific and North Africa, plus much of Europe, were heavy, rip-snorting beasts based on grass fields. Some grass fields had pierced metal planking added when the heavy planes churned them into mud during bad weather. Granted, some Pacific airfields were crushed coral, but many were grass where it would grow and hadn't been bombed out of existence before the Seabees arrived.

Next excuse?
 
There's also the design philosophy that says if you build an airplane that can fill the tanks and seats at the same time, you've probably built a plane that could stand to have bigger tanks.
 
Tantalum said:
Got caught up watching a documentary on the BF109 (link if anyone cares).. so why did we not put bigger piston engines on original GA planes?

BF109 - 1,455 hp
Spitfire - 1,470 hp
P51 - 1,490 hp

The first few personal GA planes in the 1940s and 1950s could easily have used some of the bigger more powerful piston tech available that was developed for the military, however they elected to go with itty bitty engines and very slow cruise speeds with anemic performance..

How bad ass would an original V-tail Bo (which was instroduced in 1947 for pete's sakes!) have been with a 1,400 hp V12.. so what gives? Why did the original aircraft manufacturers sell themselves short on performance? Even if you don't need *that* much power, surely we didn't have to handicap ourselves creating a situation where no real GA plane can actually fill its tanks and seats.. ?

"hey Jim, doesn't your plane have 6 seats?" "Yeah Bobby, but I have to put fuel in it too, so bad news but only you and me can go" <- the Bo has a useful load of 1,100 lbs.. throw 80 gallons of Avgas in there and you're literally left with two (maybe 3) big dudes and their luggage plus 4 empty seats... wtf?!

Educate me.
Click to expand...
2.5 hours of maintenance for 1.0 hours of flight.
 
Bell206 said:
The one thing you forget there was a ton of surplus military aircraft floating around with those big motors that "sold" for a song. No need to cram one in a brand new civilized flying cruiser. From what I was told, one could buy a brand new 140 to fetch the groceries and also keep a nice P-40B parked on the ramp when there was a "need for speed." It was definitely a different time from '46 to to about '54... at least from the stories I heard.
Click to expand...
Interesting, did not know that!

PaulS said:
Those airplanes are big even though they are single engine, they are thirsty too.
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I was surprised when I looked at the specs of the BF109 at least as far as wingspan and length that it is fairly comparable to any other Cirrus, Bonanza, Piper, etc. That huge propeller gives it a real ramp presence.. but strictly speaking they're smaller than I pictured them

Kenny Phillips said:
2.5 hours of maintenance for 1.0 hours of flight.
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Is that an honest assessment? Not doubting you, but if that's true that must have been a serious handicap for the war effort...!
 
Tantalum said:
I was surprised when I looked at the specs of the BF109 at least as far as wingspan and length that it is fairly comparable to any other Cirrus, Bonanza, Piper, etc. That huge propeller gives it a real ramp presence.. but strictly speaking they're smaller than I pictured them
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The Cirrus is 38 feet, but I'm willing to bet those airplanes have more surface area, longer chord. The BF109 was about 6900 fully loaded, the p51 could go up to 9200, they both have 32 foot wings. Great machines.
 
A buddy of mine just bought an allison v-12 which he is building a trailer for to run and display. That thing damn near weights as much as my plane!!
 
PaulS said:
The Cirrus is 38 feet, but I'm willing to bet those airplanes have more surface area, longer chord. The BF109 was about 6900 fully loaded, the p51 could go up to 9200, they both have 32 foot wings. Great machines.
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And the landing speeds were much higher. Wing loading was much higher.
 
Tantalum said:
...
Is that an honest assessment? Not doubting you, but if that's true that must have been a serious handicap for the war effort...!
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My error. Remove the decimal point.
 
For the same reason more people don't own a PC-12. Dollars. The cost of buying, operating and maintaining a 1500 hp V12 is too much for most people.
 
Tantalum said:
Fair.. but my understanding is that a PT6 is not a cheap engine to feed and maintain either.. just wondering why not a single GA manufacturer "back then" elected to do something more TBM / PC12-esq with the original tech.. the PT6 wouldn't come around for another decade or two..
Click to expand...

Compare the number of moving parts in a PT6 to the number of moving parts in a Merlin...

Also "acceptable reliability" in wartime is very different from civilian transport.
 
Non Compos Mentis said:
Awfully hard to land the heavy, rip-snorting beast on the field behind grandpa's barn.

Post WWII most airports were shorter, often grass strips.
Only the military and airlines had a mile of smooth pavement.
Click to expand...
Hank S said:
But fighters across the Pacific and North Africa, plus much of Europe, were heavy, rip-snorting beasts based on grass fields. ....
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It's not the grass, it's the length. I doubt anybody is flying P-51s in and out of a 1500 foot strip.
 
Because turbines are less complex, lighter, and cheaper per HP than the old reciprocating beasts. The tolerances are tighter on turbines, but they became cost effective with improvement in materials and manufacturing processes. As highlighted, they also have much better power to weight ratios.

The reason the small pistons endure is that they are cheaper per mile at the uber-slow speeds we fly (yes, <200KTAS is slow), so we accept the horrid mechanical reliability delta that comes with pistons.

If it makes you feel better, 'super small' turbines are equally stupid. :eek::D
 
ejensen said:
Acording to AOPA's site the P51 took off in 1000' and cleared a 50' obstacle in 1750'
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Maybe operating at the margins and at 1945 power levels with 140+ octane fuel and brave 21 year olds flying. Takeoff runs in today's lightly loaded P-51's look a lot longer than that.

That said, takeoff distance isn't the big issue. Landing distance is. Most people land a P-51 on the mains, meaning a substantially higher touchdown speed than if they stalled it on in a 3 point attitude. (You don't want to stall a P-51 - they are not forgiving.) I'd estimate 4,000' as a comfortable field length for landing a P-51 unless someone else is paying for the tires and brakes.
 
PaulS said:
The BF109 was about 6900 fully loaded, the p51 could go up to 9200, they both have 32 foot wings. Great machines.
Click to expand...

A P-51 is a much larger airplane than a -109. Side by side, it is amazing how small a -109 looks compared to a P-51 or any other US WWII fighter.

The P-51 was larger by 5' in wingspan and thousands of pounds, both in empty and loaded weight. The P-51 had 1940 aerodynamics with the underslung radiator using the Meridith effect for cooling and with a laminar flow wing. The -109 was a 1934 design, complete with 1934 aerodynamics. It survived by having a small airframe and a huge engine. That way, it could be competitive as a point defense interceptor against P-51's which were 3,000 lbs heavier in combat weight (combat weight being the aircraft's weight over target after any external stores and the aux (behind the seat) tank were gone/used up) and arrived on scene from 500 miles away. By the end of the war, -109's came up short on every measure except climb rate, and maybe turning radius below a certain speed...

6 years of additional development time was huge in the late '30's.
 
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