Grumman F-7F Tigercat
Discussion
Very valid reasons 
I was surprised to see that those double wasp radial engines only produced similar horsepower to the later Merlin engines fitted to the Hornet- I'm no expert but it surprises me that the much greater displacement of the radial didn't give a bigger horsepower advantage over the smaller Merlin, given the obvious streamlining disadvantages? I get that there are other benefits to the radial engine (air-cooling), but I was expecting a much bigger horsepower figure given the similar performance between the F7F and the Hornet, despite the former weighing a load more!
Any experts care to point out the fundamental thing I'm missing?
Is it just a case that both aircraft were simply reaching the speed limits of what a prop-driven aircraft could achieve and so the performance is comparable despite one being much lighter with similar horsepower?
I was surprised to see that those double wasp radial engines only produced similar horsepower to the later Merlin engines fitted to the Hornet- I'm no expert but it surprises me that the much greater displacement of the radial didn't give a bigger horsepower advantage over the smaller Merlin, given the obvious streamlining disadvantages? I get that there are other benefits to the radial engine (air-cooling), but I was expecting a much bigger horsepower figure given the similar performance between the F7F and the Hornet, despite the former weighing a load more!
Any experts care to point out the fundamental thing I'm missing?
Is it just a case that both aircraft were simply reaching the speed limits of what a prop-driven aircraft could achieve and so the performance is comparable despite one being much lighter with similar horsepower?
Squirrelofwoe said:
Very valid reasons
I was surprised to see that those double wasp radial engines only produced similar horsepower to the later Merlin engines fitted to the Hornet- I'm no expert but it surprises me that the much greater displacement of the radial didn't give a bigger horsepower advantage over the smaller Merlin, given the obvious streamlining disadvantages? I get that there are other benefits to the radial engine (air-cooling), but I was expecting a much bigger horsepower figure given the similar performance between the F7F and the Hornet, despite the former weighing a load more!
Any experts care to point out the fundamental thing I'm missing?
Is it just a case that both aircraft were simply reaching the speed limits of what a prop-driven aircraft could achieve and so the performance is comparable despite one being much lighter with similar horsepower?
With careful cowling design, by the end of World War 2, the drag created by radials was broadly similar to that of liquid cooled in line engines. That's why most of the last generation of large piston engines were air cooled radials and not liquid cooled.I was surprised to see that those double wasp radial engines only produced similar horsepower to the later Merlin engines fitted to the Hornet- I'm no expert but it surprises me that the much greater displacement of the radial didn't give a bigger horsepower advantage over the smaller Merlin, given the obvious streamlining disadvantages? I get that there are other benefits to the radial engine (air-cooling), but I was expecting a much bigger horsepower figure given the similar performance between the F7F and the Hornet, despite the former weighing a load more!
Any experts care to point out the fundamental thing I'm missing?
Is it just a case that both aircraft were simply reaching the speed limits of what a prop-driven aircraft could achieve and so the performance is comparable despite one being much lighter with similar horsepower?
Air cooled radials offer a number of advantages over liquid cooled. By definition, they do not need to carry any coolant - so loss of coolant is not an issue. This is important in combat aircraft where a single bullet in a radiator or coolant line can cause a liquid cooled engine to seize very quickly.
Air cooled radials tend to be very robust. There are lots of stories of aircraft using radials coming back with one or two cylinders completely missing off an engine.
The Tigercat was a US Navy design. The US Navy always insisted on air cooled engines for their carrier borne aircraft. Partly for the reasons I mentioned above but also, because these aircraft were designed to be carried on ships, with a fleet of air cooled engined aircraft, the ship does not have to carry large quantities of coolant on board.
Ironically, the Tigercat was not used to any great extent on board the Navy's carriers. The Navy were not keen on twin engined designs for carrier use. Asymmetric power delivery, especially if it is caused by an engine failure on take off or landing, can be catastrophic on a carrier - so they preferred single engine types. In the end, they mainly served with shore based Marine units.
The Royal Navy (and the RAF) tried out many US designs that they didn't end up putting into service, or used them in roles not originally intended.
Like many late war designs, the Tigercat arrived too late to be put into front line service before the cessation of hostilities. As a result, it was not built in the large numbers originally intended. Also, the arrival of the jet engine showed that pursuing further development of piston powered designs was not really worthwhile.
Despite all that, they were very good aircraft and the stayed in service into the early 1950s, especially as night fighters with the US Marines.
After military service, a number soldiered on in various specialist roles in civil life, such as fire fighting. Most of the surviving Tigercats are those that were used up until the 1980s fighting forest fires.
Like many late war designs, the Tigercat arrived too late to be put into front line service before the cessation of hostilities. As a result, it was not built in the large numbers originally intended. Also, the arrival of the jet engine showed that pursuing further development of piston powered designs was not really worthwhile.
Despite all that, they were very good aircraft and the stayed in service into the early 1950s, especially as night fighters with the US Marines.
After military service, a number soldiered on in various specialist roles in civil life, such as fire fighting. Most of the surviving Tigercats are those that were used up until the 1980s fighting forest fires.
Squirrelofwoe said:
Very valid reasons
I was surprised to see that those double wasp radial engines only produced similar horsepower to the later Merlin engines fitted to the Hornet- I'm no expert but it surprises me that the much greater displacement of the radial didn't give a bigger horsepower advantage over the smaller Merlin, given the obvious streamlining disadvantages? I get that there are other benefits to the radial engine (air-cooling), but I was expecting a much bigger horsepower figure given the similar performance between the F7F and the Hornet, despite the former weighing a load more!
Any experts care to point out the fundamental thing I'm missing?
Is it just a case that both aircraft were simply reaching the speed limits of what a prop-driven aircraft could achieve and so the performance is comparable despite one being much lighter with similar horsepower?
Re. The engines, I think it was probably a question of development, and development potential. The Merlin was continuously developed over many years, with incremental gains in hp (see “Not much of an engineer by Stanley Hooker). I doubt the Double Wasp had so much resource thrown at it. I was surprised to see that those double wasp radial engines only produced similar horsepower to the later Merlin engines fitted to the Hornet- I'm no expert but it surprises me that the much greater displacement of the radial didn't give a bigger horsepower advantage over the smaller Merlin, given the obvious streamlining disadvantages? I get that there are other benefits to the radial engine (air-cooling), but I was expecting a much bigger horsepower figure given the similar performance between the F7F and the Hornet, despite the former weighing a load more!
Any experts care to point out the fundamental thing I'm missing?
Is it just a case that both aircraft were simply reaching the speed limits of what a prop-driven aircraft could achieve and so the performance is comparable despite one being much lighter with similar horsepower?
The other thing is the fundamentally limited development potential of an air-cooled engine due to cooling fin area. You’re basically stuck with trying to get rid of any increased heat generated from burning extra fuel, from already well optimised cooling fins. With a liquid cooled engine there are more options for increasing cooling, and of course liquid is much better at transferring heat than air.
aeropilot said:
Total loss said:
The Royal Navy FAA had one or two of them.
Two.TT346 & TT349.
Evaluated and rejected for FAA use in the spring of 1945, with FAA preferring the Sea Hornet instead.
I used to have a pic of one of then at Boscombe Down, you can guess who flew them, considering his thoughts on the Hornet, the Tigercat wouldn't have stood much of a chance against it.
Eric Mc said:
The US Navy always insisted on air cooled engines for their carrier borne aircraft. Partly for the reasons I mentioned above but also, because these aircraft were designed to be carried on ships, with a fleet of air cooled engined aircraft, the ship does not have to carry large quantities of coolant on board.
That's an interesting point that I hadn't considered- definitely easier logistics with a fleet of air-cooled aircraft with no need for carrying coolant in addition to all the other support stuff the carriers (and fleet) had to carry for operations.dr_gn said:
The other thing is the fundamentally limited development potential of an air-cooled engine due to cooling fin area. You’re basically stuck with trying to get rid of any increased heat generated from burning extra fuel, from already well optimised cooling fins. With a liquid cooled engine there are more options for increasing cooling, and of course liquid is much better at transferring heat than air.
That makes sense. I guess that's why (to bring it back to cars) even the Porsche 911 ended up going to water-cooling eventually to keep the horsepower increasing. Obviously less of a requirement for bullet damage resistance in that application!Squirrelofwoe said:
dr_gn said:
The other thing is the fundamentally limited development potential of an air-cooled engine due to cooling fin area. You’re basically stuck with trying to get rid of any increased heat generated from burning extra fuel, from already well optimised cooling fins. With a liquid cooled engine there are more options for increasing cooling, and of course liquid is much better at transferring heat than air.
That makes sense. I guess that's why (to bring it back to cars) even the Porsche 911 ended up going to water-cooling eventually to keep the horsepower increasing. Obviously less of a requirement for bullet damage resistance in that application!Squirrelofwoe said:
dr_gn said:
The other thing is the fundamentally limited development potential of an air-cooled engine due to cooling fin area. You’re basically stuck with trying to get rid of any increased heat generated from burning extra fuel, from already well optimised cooling fins. With a liquid cooled engine there are more options for increasing cooling, and of course liquid is much better at transferring heat than air.
That makes sense. I guess that's why (to bring it back to cars) even the Porsche 911 ended up going to water-cooling eventually to keep the horsepower increasing. Obviously less of a requirement for bullet damage resistance in that application!aeropilot said:
Except, in aero piston engine development terms, no water cooled production engine came close to developing the power outputs of the final big American radial engines such as the Wright R-3350 & the P&W R-4360, so I wouldn't say that had jet engines not arrived, that water-cooling would have been needed for more powerful piston aero engines.
Indeed, the last great piston aero engines were all air cooled. I would suggest the last practical and powerful liquid cooled engine was the Rolls Royce Griffon. The final generation of powerful piston engines were used, not on fighters - where speed (and therefore streamlining and frontal area might be a major consideration) but on airliners and military transports where ruggedness and reliability were the most important considerations.
The Lockheed Starliner had four Wright 3350 turbo-compound radials producing 3,400 hp each.
The Boeing 377 Stratocruiser had four Pratt and Whitney 4360 radials of 3,500 hp each.
In the case of the Stratocruiser, that was really the end of where you could go with piston power for practical use. The 4360 were not the most reliable of engines and shut downs were not unusual.
But, by the end of the 1940s, the emphasis in engine development had already begun to move towards the gas turbine which everyone could see had enormous potential without the complexity of these last generation piston engines.
Eric Mc said:
aeropilot said:
Except, in aero piston engine development terms, no water cooled production engine came close to developing the power outputs of the final big American radial engines such as the Wright R-3350 & the P&W R-4360, so I wouldn't say that had jet engines not arrived, that water-cooling would have been needed for more powerful piston aero engines.
Indeed, the last great piston aero engines were all air cooled. I would suggest the last practical and powerful liquid cooled engine was the Rolls Royce Griffon. The final generation of powerful piston engines were used, not on fighters - where speed (and therefore streamlining and frontal area might be a major consideration) but on airliners and military transports where ruggedness and reliability were the most important considerations.
The Lockheed Starliner had four Wright 3350 turbo-compound radials producing 3,400 hp each.
The Boeing 377 Stratocruiser had four Pratt and Whitney 4360 radials of 3,500 hp each.
In the case of the Stratocruiser, that was really the end of where you could go with piston power for practical use. The 4360 were not the most reliable of engines and shut downs were not unusual.
aeropilot said:
Eric Mc said:
aeropilot said:
Except, in aero piston engine development terms, no water cooled production engine came close to developing the power outputs of the final big American radial engines such as the Wright R-3350 & the P&W R-4360, so I wouldn't say that had jet engines not arrived, that water-cooling would have been needed for more powerful piston aero engines.
Indeed, the last great piston aero engines were all air cooled. I would suggest the last practical and powerful liquid cooled engine was the Rolls Royce Griffon. The final generation of powerful piston engines were used, not on fighters - where speed (and therefore streamlining and frontal area might be a major consideration) but on airliners and military transports where ruggedness and reliability were the most important considerations.
The Lockheed Starliner had four Wright 3350 turbo-compound radials producing 3,400 hp each.
The Boeing 377 Stratocruiser had four Pratt and Whitney 4360 radials of 3,500 hp each.
In the case of the Stratocruiser, that was really the end of where you could go with piston power for practical use. The 4360 were not the most reliable of engines and shut downs were not unusual.
A test Sabre was said to produce 5,000hp. Rolls Royce also had a H24 engine in development at the same time, but as we know, jet & turbo props were at the forefront of engine development here in the UK immediately post WWII.
Squirrelofwoe said:
Eric Mc said:
The US Navy always insisted on air cooled engines for their carrier borne aircraft. Partly for the reasons I mentioned above but also, because these aircraft were designed to be carried on ships, with a fleet of air cooled engined aircraft, the ship does not have to carry large quantities of coolant on board.
That's an interesting point that I hadn't considered- definitely easier logistics with a fleet of air-cooled aircraft with no need for carrying coolant in addition to all the other support stuff the carriers (and fleet) had to carry for operations.Gassing Station | Boats, Planes & Trains | Top of Page | What's New | My Stuff