AHC/WI: H-Block Engines Adopted for Aircraft Use

[Delta Force]

An H-block engine is essentially two flat engines joined together and driving their own crankshafts. While H-block engines have lower power to weight ratios compared to some other designs, they are shorter than other multi-bank engine designs and combine some of the reliability of twin-engine operation, as damage or component failure on one cylinder bank doesn't necessarily affect operation of the other cylinder bank.

Although a few H-block engines were designed for aircraft, they didn't see widespread service. Also, the H-block engines often suffered from reliability problems or or were underpowered for the designs they were used in. Would it have been possible for H-block engines to have been adopted for use on smaller aircraft as a means of improving aircraft recoverability and survivability?

 

[Carl Schwamberger]

Where else were they commonly used?

 

[Andras]

The Napier Sabre was an H block 24 cylinder engine used in the Tempest and Typhoon.
http://en.wikipedia.org/wiki/Napier_Sabre

While originally developed in the late 30s, it didn't get fully perfected until 1944. While it was twice as powerful as contemporary V12s, it was about the same as the R2800 in US service.

 

[Delta Force]

Where else were they commonly used?

Automobile racing of course. British Racing Motors won the 1966 American Grand Prix using a Lotus 46 equipped with an H-block engine.

Also, the Brough Superior Golden Dream used an H-block engine, but only five were built due to the outbreak of World War II, and Brough was a luxury motorcycle company anyways. After the war Wooler (another British luxury motorcyle company) exhibited a prototype motorcycle similar to the Golden Dream at the 1948 and 1951 British International Motor Show.

It seems that the H-block engine was only used by British automobile and aircraft firms, although the United States built some prototype H-block aircraft engines.

The Napier Sabre was an H block 24 cylinder engine used in the Tempest and Typhoon.
http://en.wikipedia.org/wiki/Napier_Sabre

While originally developed in the late 30s, it didn't get fully perfected until 1944. While it was twice as powerful as contemporary V12s, it was about the same as the R2800 in US service.

I wonder if the rather difficult teething process was inherent to H-block engines, or simply something else? H-block engines seem to have had a reputation for being temperamental in British service.

 

[Just Leo]

Nice of you to bring up motorcycles. By the way, the Ariel Square Four was a U engine. Surprised me.

Another H engine was the Fairey P-24 Monarch, with which 2 sides ran independently, each running one half of the contra-rotating propellers. It could have found a use, and been further developed, but the Government was firmly against doing engine business with Richard Fairey because he had licensed and produced a Curtiss engine that they had wanted to, and did steal. The copy, indirectly, became the Kestrel. Its installation on a testbed Battle may explain why the aircraft was too large for the Merlin. It has been suggested that it would have been ideal installed on a maritime patrol aircraft, with half power for long range cruise. In the end, both the Blackburn B-20 and the Saro Lerwick came to inglorious ends, so no such airframes existed.

The Napier Dagger was an air-cooled H engine, installed on the Hector and several other aircraft, none successfully because the rear cylinders didn't cool properly, leading to loss of power and ultimate failure. This, by the way, was the ultimate failure of the Ariel Square Four.

The Napier Sabre was intended to be a massive hyper engine, but that's the stuff that dreams are made of. It would have been an excellent BBQ starter.

The American engines were made by companies already successful with their regular in production engines, and nobody was looking forward to the usual development times during a war, let alone the jet age.

 

[Tentrees]

A thought...

IF the Napier Sabre could have its production problems sorted by 1939 and intro-ed the water cooled and fuel injected variant by that fall what impact would a Westland Whirl Wind engine with this engine have had to allied bomber streams and would the engine be used on the Mosquito or other light bombers?

Can you imagine a Whirlwind with a hundred mile an hour speed advantage over the 109 and the effect that mass of cannon would have had on a Henkel or JU series aircraft?

 

[Just Leo]

IF the Napier Sabre could have its production problems sorted by 1939 and intro-ed the water cooled and fuel injected variant by that fall what impact would a Westland Whirl Wind engine with this engine have had to allied bomber streams and would the engine be used on the Mosquito or other light bombers?

Can you imagine a Whirlwind with a hundred mile an hour speed advantage over the 109 and the effect that mass of cannon would have had on a Henkel or JU series aircraft?

This reminds me of a quote from the movie, "When Harry Met Sally".

 

[Delta Force]

Snip.

What aircraft is in that picture?

 

[pdf27]

What aircraft is in that picture?

Fairey Battle.

 

[Foxvc10]

I think its a Fairey Battle. Used as an Engine Testbed. Very Interesting photo that I havent seen before.

 

[Just Leo]

It is a Fairey Battle with P-24 engine which could have been the standard engine with twice the power, if could have beens could have been. If the P-24 had received half the attention and funding lavished on the Sabre, nobody knows what would have been because they didn't. A Sabre also found its way to the nose of a Battle, for testing. I presume they got paid to do that one, but they received squat for the Monarch.

 

[sonofpegasus]

I believe that is the P16 Fairey Queen engine in the Fairey Battle test aircraft in the USA in late 1941. If it was the P24 Fairey Monarch engine there would be 6 exhausts in each bank not the four clearly visible. The engine at the FAA museam in Yeovelton is possibly also a P16 not a P24 as usualy stated. There is some arguement over whether the P24 had a strage exaust layout of six cylinders with 4 exhaust stubs, single on the first and last cylinder in each bank with the middle two exhausts being paired to two cylinders eah, though I have never seen a technial drawing to confirm this.

 

[Andras]

For a non-aircraft use, you could use them on the larger motor torpedo boats which typically had 3 V12s. 2 H24s on two shafts would have ~33% more power then 3 V12s.

 

[Just Leo]

I believe that is the P16 Fairey Queen engine in the Fairey Battle test aircraft in the USA in late 1941. If it was the P24 Fairey Monarch engine there would be 6 exhausts in each bank not the four clearly visible. The engine at the FAA museam in Yeovelton is possibly also a P16 not a P24 as usualy stated. There is some arguement over whether the P24 had a strage exaust layout of six cylinders with 4 exhaust stubs, single on the first and last cylinder in each bank with the middle two exhausts being paired to two cylinders eah, though I have never seen a technial drawing to confirm this.

The US report was fairly thorough, and described a 24 cylinder engine. They looked. The intake manifold was cast into the head with 4 intake valves facing each other. That leaves the center cylinders' exhaust valves also facing each other in the head casting, looking for a way out. I believe the Siamese have a saying. "Why tempt fate, bifurcate."

 

[Delta Force]

For a non-aircraft use, you could use them on the larger motor torpedo boats which typically had 3 V12s. 2 H24s on two shafts would have ~33% more power then 3 V12s.

It might be more difficult to maintain an H-block engine mounted in a ship, as opposed to one mounted in an aircraft.