Thursday, March 01, 2018

testing rebuilt engines.... evidently the prop orientation's not very important when testing engines

9 comments:

  1. That second picture shows different hubs, I wonder if they were testing different engines in those two planes? I have no idea if those early engines all turned the same way or not.

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    1. If we suppose that the closest plane in both photos is the same one, since it appears to be and has 2 guys trying to spin it, then it's the oddball, and many of the other planes have the prop in the flipped configuration

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    2. but you're onto something, I hadn't considered that not all engines would turn clockwise on the crank when viewed from the front

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  2. That is interesting. Usually aircraft with two or more engines have engines that rotate the props toward the fuselage (there are exceptions to this) in order to lessen the torque induced roll if one engine fails. But it is sure a head scratcher to have two similar single engine planes with different rotation. The different rotation would mean the control rigging and tail trim would have to be slightly different. Perhaps each of these aircraft have different engines, such as one has a Hispano, and the other a Rolls.

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  3. Jesse, I'm still digging on this one. Thus far: these are Airco (DeHavilland) DH4's which had several engines. The one on the right is a Rolls Royce Eagle, which was the preferred engine. It had the Siddeley Puma, which had a lot of reliability issues. The one on the left is 'probably' equipped with a Royal Aircraft Factory RAF3 engine, which as I read it had a 0.5:1, left-hand tractor reduction gear. The Royal Air Force DH4's had four bladed propellers because they provided better ground clearance. The US forces had license built DH4's with the Liberty engine. You can tell them (besides the US markings of course) by the two bladed propellers they used. There was also a version built to be sold to Russia with a Fiat engine.

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  4. In the first photo, the two aircraft in the distance with no cowling are Airco DH9's, with the Siddeley Puma engines.

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  5. The planes with the reduction gear have the propeller mounted lower in the fuselage than the direct-driven propellers,too.

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    1. Yes, that's right the Eagle in particular needed reduction because it operated at around 2400 rpm.

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