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FOKKER DVIII - in flight | The Vintage Aviator

 

Yesterday I watched one of these take off...and climb like crazy.

According to Wikipedia, the climb rate is 1640ft a minute, or 10min 45sec to13,000ft.

MAUW 605Kg, engine Oberursel UR.II 9-cyl. air-cooled rotary 110 hp

 

Pretty good for a 100year old microlight!!!

Edited by IBob
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Interesting writeup on the reverse engineering and subsequent build of new Oberursal UR.II engines to go in the 'new ' Fokker DVIIIs (of which there are now at least 2):

 

https://thevintageaviator.co.nz/projects/oberursel-engine/oberursel-ur-ii-rotary-engine-build-history

Edited by IBob
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Large props, (high torque)  and relatively low total mass. Good climb rates as well . A feature of rotaries but they had little application to civil use after the war ended. They were never revived.  except by enthusiasts  who have done a few replica's.  Nev

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15 minutes ago, facthunter said:

Large props, (high torque)  and relatively low total mass. Good climb rates as well . A feature of rotaries but they had little application to civil use after the war ended. They were never revived.  except by enthusiasts  who have done a few replica's.  Nev

 

As noted earlier, they're building new ones here at Hood. And far more complicated engines too. The reason being that the very small pool of surviving originals has pretty much dried up. So to build the aircraft of the time, they are having to build the engines of the time too.

Not much demand, admittedly: mostly museums and private collections.

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They are very light for their (high) displacement. Thin alloy steel cylinders which do warp sometimes, are machined from billet .Max RPM around 1200 and a large gyroscopic effect as only the crankshaft stays still and the engine with Prop attached rotates on it.. They were ALWAYS 4 stroke although some had spring loaded valves in each piston, which (where fitted) required a lot of attention. The usual lubricant was Castor oil and lots of it which got all over everything including the pilot. and tents under the approach path. Nev

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5 hours ago, onetrack said:

I've often wondered how the current builders have got around the oil spray problem. Do they use modified current-technology seals and gaskets and rings?

In many early engines, the valve gear is exposed, so there is no way to capture and recirculate the oil that lubricates the rockers and stems: it is what is known as a total loss oil system. In something like the rotary Oberursal engine, there would be the added difficulty of how to get oil back from the heads, given that the whole engine is rotating. As Facthunter said, this oil blows back over aircraft and pilot. And you get whiffs of it all over the airfield when these things are flying.

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Rotary engines take air and fuel into the crankcase through the hollow (stationary) crankshaft. From there it makes it's way to the individual cylinder inlet ports, usually via external duct pipes. To maintain crankcase etc lubrication, oil is injected with the air fuel mixture, as it is in 2-stroke motors, though the rotary is a 4-stroke motor.

Here is an interesting summary: https://www.historynet.com/the-truth-about-rotaries.htm

It includes the quote: “Rotary engines became quickly outdated for a couple of reasons, but mostly because of the large quantity of Castrol required to keep a squadron of rotary-powered airplanes in the air. Most rotary engines consume about five or six quarts of oil per hour.”

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On 23/12/2020 at 6:34 AM, IBob said:

In many early engines, the valve gear is exposed, so there is no way to capture and recirculate the oil that lubricates the rockers and stems: it is what is known as a total loss oil system. In something like the rotary Oberursal engine, there would be the added difficulty of how to get oil back from the heads, given that the whole engine is rotating. As Facthunter said, this oil blows back over aircraft and pilot...

This heroic pilot had to regularly use his scarf to wipe the castor oil off his goggles. 
 

 

CD195373-F740-499D-975D-8F4360BB778E.jpeg

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Supposedly the pilots also ingested  the oil, and suffered the laxative results.

A few years back I won a raffle for a fly in an SE5a: to enter, I bought a ticket, but also had to down a large tot of castor oil. I was also offered a tot of some fruit liquer (blackcurrant?), which some WW1 pilots claimed as an antidote.

They told me it would take 2 to 3 hrs to start emptying my system. They were about right............

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5 minutes ago, pmccarthy said:

You were conned, as I am sure you know, the SE5A did not have a rotary. But I am still envious.

The story goes that Rolls Royce was ordered to produce an air-cooled motor for this aircraft, but quickly decided to stay with what they knew best. The result was this big, reliable water-cooled engine.

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11 hours ago, pmccarthy said:

You were conned, as I am sure you know, the SE5A did not have a rotary. But I am still envious.

The raffle was for a fly in a WW1 aircraft.

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On 23/12/2020 at 10:33 AM, IBob said:

"Most rotary engines consume about five or six quarts of oil per hour.”

You could work out the miles per gallon rate for both oil and fuel for this mode of transport.

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