Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!gem.mps.ohio-state.edu!tut.cis.ohio-state.edu!att!cbnews!military From: dyson@tut.cis.ohio-state.edu (mark l dyson) Newsgroups: sci.military Subject: Re: Rotary engine airplane troubles Message-ID: <10622@cbnews.ATT.COM> Date: 26 Oct 89 01:28:06 GMT References: <10577@cbnews.ATT.COM> Sender: military@cbnews.ATT.COM Organization: Ohio State University Computer and Information Science Lines: 57 Approved: military@att.att.com From: dyson@tut.cis.ohio-state.edu (mark l dyson) In article <10577@cbnews.ATT.COM> entropy@pawl.rpi.edu (Speaker for the Clams) writes: > I've heard that some early WWI aircraft such as the >Fokker DR1 and Sopwith Pup were designed so that the engine >was fixed to the propeller shaft and the entire engine spun >round and round within the fuselage. The result was that >these planes could execute very fast right turns but could >only turn left very slowly. > Does anyone know for sure if this is true? If so, >how fast were the left and right turns, respectively? What >tactics were evolved to take advantage of this >peculiarity? It is very true. The most notable of the aircraft with this engine arrangement were (not limited to) the Nieuport 11, 17, 28; Sopwith Camel; Fokker Dr1; Fokker DVIII; and many more. I don't have the exact performance stats in front of me, but here are some approximations: A Sopwith Camel, flying from 60-80 mph could turn about equally well in either direction. >From 90-110 mph the torque increased to a point where a right turn was possible at as much as 1/2 the diameter of the left. From the mid-100's up to 200+ there was still as much as a 1/3 reduction in turn radius, but the higher momentum of the aircraft would mitigate the torque benefit somewhat. These figures are approximate, but the ratio holds more or less for any of the rotary-engined planes. [mod.note: I meant to mention this yesterday... isn't the correct term "radial", not "rotary" ? My RX-7 has a rotary engine, I thought A/C had radials. Or is a spinning radial also called a rotary ? - Bill ] Tactics for these planes are fairly obvious: if you get into a scissor or circle duel, keep the target on your right, and you get better turn rates. Against a Fokker Dr1, the Camel's advantage was nearly nil, though, as they had almost identical turn rates in all envelopes. The Dr1's forte was its lift, so it had the advantage of making the same turn rates as a Camel opponant, with lower altitude losses per turn. Couple that with the Camel's better dive, though, and the Dr1 wasn't always free to pursue the height advantage. Getting the picture? Almost every plane on the front had some forte' or another. The bottom line was, as always, how well a pilot could react to an enemy's actions, and control the engagement. Why a rotary? In a word, reliability. A rotary could force-feed the lubricant via centripetal force through the center of the engine and up to each cylinder. Carburation was likewise simplified. A stationary crankshaft could be made heavier, and less prone to breakage. One big problem with them was that the throttles were essentially non-adjusting, due to the simplified fuel system. The engine generally self-adjusted to the flying conditions, but tended to stay at a constant rpm at a given altitude. Modifications to airspeed were made with pitch adjustment. I hope this clears up some of your questions. -Mark-