Peter Christy Posted February 24, 2018 Share Posted February 24, 2018 My interests in classic aerobatic models is firmly in the "Taurus" era, but I know many later classic models used rear exhaust engines and tuned pipes. I've been assisting the widow of a deceased modelling friend dispose of his assets, and amongst them I've found a pristine YS 61 pumper, rear exhaust. I may also have found a pipe for it, but not the manifold adapter (yet!). I haven't advertised this anywhere yet as I thought it may be of interest to someone here, so I'm offering it here first. If anyone wants further information, please message me and I will answer as best I can. All I know about YS is that my son used them in preference to OS in Helicopter F3C contests, as they worked, whereas the OS "C" spec didn't - well, not reliably, anyway! Cheers, -- Pete Quote Link to comment Share on other sites More sharing options...
Robert Welford Posted February 24, 2018 Share Posted February 24, 2018 Pete, What version of YS 61 is it? Does it have a round head, or more square head? The Ys 61 LS (long stroke) had a square head. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted February 24, 2018 Share Posted February 24, 2018 Interested, whatever version it is. Quote Link to comment Share on other sites More sharing options...
Peter Christy Posted February 25, 2018 Author Share Posted February 25, 2018 The engine is still over at Jill's. I'll pick it up on Monday and put some pix up. Its still in the box and appears un-run. I'm not an expert on YS engines, other than being able to recognise one, but this one stood out because of the rear exhaust - which might suit some of the later "classic" aerobatic designs. More info will follow when I pick the engine up... -- Pete Quote Link to comment Share on other sites More sharing options...
Peter Christy Posted February 25, 2018 Author Share Posted February 25, 2018 Managed to get over and pick the engine up this morning, so here's an update (and a bonus!): The label on the box says "FRH", implying its a helicopter engine. However, it doesn't have a heatsink head, just the ordinary round one (not a long-stroke, then?). The needle valve and pressure regulator are present, and the engine has clearly never been run. It looks like it was one of a pair, as there was a second box that contained prop washers, etc, so the other one may have been in a helicopter that has already sold. Rear exhausts were not common on heli engines, and on most heli engines, the only difference was the fitting of a heatsink head to assist with cooling. If this is a heli engine, I wouldn't worry! It should work equally well in a fixed-wing aircraft. Now for the bonus! I also found this: Its an OS61-RF-HS, also brand new and un-run! This definitely is a heli engine, but again, the rear exhaust layout is not popular in helis, and the heatsink head may be advantageous in a fully cowled engine. Many later "classic" aerobatic designs seemed to use cowled engines and tuned pipes, so again, this may well be of interest to anyone building such a model. I'm in South Devon if anyone local is interested in examining the merchandise, otherwise I'll answer any questions to the best of my ability. The modern equivalent of these engines sell for well north of £200. Obviously these are worth what someone is prepared to pay, but I would hope to realise around 50% of their new price as a guide. The money will go to the deceased's widow. Thanks for looking! -- Pete Edited By Peter Christy on 25/02/2018 12:52:10 Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted February 15, 2021 Share Posted February 15, 2021 (edited) I just dropped onto this thread and that picture of the OS RF heli engine explains something I had been wondering about for a while now. Back in the late 90s I bought an OS RF 61 aero from Just Engines at the Sandown show it was reduced to a round £100 and seemed to be the end of a line they were disposing of. When I got it home and compared it with my existing one I noticed some differences, the main one was that the carb, it looked just like the one in the packet seen above. Also the shaft only had a 1/4" thread where they normally had a 5/16" thread. I'm guessing the heat sink is removable and this is why they could sell them as an aero engine. It does seem odd though though because heli engines don't normally come with prop drivers. Anybody have any more detail on this variant. You can see the difference in the crankshafts between the original and the variant... Edited February 15, 2021 by Andy Stephenson Quote Link to comment Share on other sites More sharing options...
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