IBob Posted December 19, 2020 Share Posted December 19, 2020 (edited) 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 December 19, 2020 by IBob 1 1 Link to comment Share on other sites More sharing options...
pmccarthy Posted December 19, 2020 Share Posted December 19, 2020 I want one but that extra 5kg makes it impossible. Link to comment Share on other sites More sharing options...
IBob Posted December 19, 2020 Author Share Posted December 19, 2020 (edited) 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 December 19, 2020 by IBob 1 1 1 Link to comment Share on other sites More sharing options...
Student Pilot Posted December 22, 2020 Share Posted December 22, 2020 The old film of Fokker Triplanes taking off shows them airborne in about 50 metres 1 Link to comment Share on other sites More sharing options...
facthunter Posted December 22, 2020 Share Posted December 22, 2020 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 1 Link to comment Share on other sites More sharing options...
IBob Posted December 22, 2020 Author Share Posted December 22, 2020 They knew how to build light.....probably a question of having to, but impressive nevertheless. Link to comment Share on other sites More sharing options...
IBob Posted December 22, 2020 Author Share Posted December 22, 2020 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. 1 Link to comment Share on other sites More sharing options...
facthunter Posted December 22, 2020 Share Posted December 22, 2020 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 1 Link to comment Share on other sites More sharing options...
onetrack Posted December 22, 2020 Share Posted December 22, 2020 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? Link to comment Share on other sites More sharing options...
IBob Posted December 22, 2020 Author Share Posted December 22, 2020 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. 1 1 Link to comment Share on other sites More sharing options...
IBob Posted December 22, 2020 Author Share Posted December 22, 2020 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.” Link to comment Share on other sites More sharing options...
IBob Posted December 23, 2020 Author Share Posted December 23, 2020 It's a dead giveaway: 'Sniffs the air......" Yep, them Fokkers have been around again..."............ Link to comment Share on other sites More sharing options...
Old Koreelah Posted December 24, 2020 Share Posted December 24, 2020 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. 1 2 Link to comment Share on other sites More sharing options...
IBob Posted December 25, 2020 Author Share Posted December 25, 2020 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............ 1 2 Link to comment Share on other sites More sharing options...
pmccarthy Posted December 25, 2020 Share Posted December 25, 2020 You were conned, as I am sure you know, the SE5A did not have a rotary. But I am still envious. Link to comment Share on other sites More sharing options...
Old Koreelah Posted December 25, 2020 Share Posted December 25, 2020 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. Link to comment Share on other sites More sharing options...
IBob Posted December 25, 2020 Author Share Posted December 25, 2020 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. Link to comment Share on other sites More sharing options...
eightyknots Posted December 25, 2020 Share Posted December 25, 2020 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. Link to comment Share on other sites More sharing options...
eightyknots Posted December 25, 2020 Share Posted December 25, 2020 12 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. Link to comment Share on other sites More sharing options...
eightyknots Posted December 25, 2020 Share Posted December 25, 2020 This is a nice picture of the engine from Wikipedia. 1 Link to comment Share on other sites More sharing options...
F10 Posted May 10, 2021 Share Posted May 10, 2021 Castor oil....so, the sight of Richtoffens circus diving out of the sun wasn’t the only reason underwear needed to be washed....however, let me add, all respect to these very brave pilots of the Great War, it was brutal. Interesting to think the fighters of yesterday, are the RA aircraft of today. The take off weight weight thing is interesting, next time I see someone buying man shakes at the chemist, I know he’s trying to get his GA aircraft onto the RA register! Link to comment Share on other sites More sharing options...
Old Koreelah Posted May 10, 2021 Share Posted May 10, 2021 59 minutes ago, F10 said: Castor oil....so, the sight of Richtoffens circus diving out of the sun wasn’t the only reason underwear needed to be washed....however, let me add, all respect to these very brave pilots of the Great War, it was brutal.. When we were kids our old bus-driver neighbour told of watching the Red Baron from the trenches. It wasn’t much like the legend. Being a nobleman, Von Richthofen had a team of pilots whose job was to herd any hapless allied flyer into his gunsights. 1 Link to comment Share on other sites More sharing options...
IBob Posted May 10, 2021 Author Share Posted May 10, 2021 My understanding is that Richthofen was at best an average pilot, but a good game marksman, which is to say he had a better than average idea of where to point his gun/s... Link to comment Share on other sites More sharing options...
F10 Posted May 10, 2021 Share Posted May 10, 2021 (edited) I had heard he preferred attacking 2 seaters....also, he wasn’t so great a pilot, but was a brilliant marksman....so often the difference between aces and the others, in both wars. The ability to shoot. That does of course, require good flying, shooting well. Erich Hartmann was flying a patrol, when below them, they spotted 3 Stormoviks in a close echelon formation. Telling the others to stay up for top cover, he rolled his 109 inverted and his patrol watched him make one high speed pass behind them, then zoom climb up and rejoin them. The Stormoviks wobbled about, but carried on, Then all three propellers stopped. Hartmann had nailed all three belly coolant radiators in one pass.The belly radiators were the one weak spot of the heavier armour plated Stormovik. Back at base, he had used less than half his cannon rounds. That is how well he could shoot, and why he’s the top scoring fighter pilot of all time. Edited May 10, 2021 by F10 2 1 Link to comment Share on other sites More sharing options...
Bruce Tuncks Posted May 11, 2021 Share Posted May 11, 2021 I think I read that the Fokker DV111 was the best WW1 plane. Was this so? Link to comment Share on other sites More sharing options...
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