John Tee Posted July 29, 2020 Share Posted July 29, 2020 I have an 11x 7 pusher prop on an HB61 PDP i/c engine. I have always had the makers logo facing the direction of travel on all my props. The leading edge of this prop and the pitch are looking correct using this method. But the hub seems backward to me as the face that the washer and prop nut are up against is the one I would normally have aginst the prop driver of the engine. I don't suppose it will make too much difference once tightened up, but would appreciate some comments. Sorry about the size of the image but there doesn't seemto be the usual resolution sttings on my latest camera. John Quote Link to comment Share on other sites More sharing options...
wingcoax Posted July 29, 2020 Share Posted July 29, 2020 John, I have two models with pushers, Both are mounted as normal with flat side to washer and nut. Steve. Quote Link to comment Share on other sites More sharing options...
John Tee Posted July 30, 2020 Author Share Posted July 30, 2020 Hi Steve, if you look at the hub in the picture above, that is the side I have the nut and washer on. The leading edge of the prop blade is then correct, but if I turn it round to put this face on the prop driver the leading edge is wrong. I will have to try it and see which way gives most thrust. Cant fly it yet as it has to be noise tested at the club. john Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 30, 2020 Share Posted July 30, 2020 As you believe John, the close up photo shows the back of the hub So the leading edge should be on the table That makes sense if the 61 points away from the rear of the model One of my cameras has a small lever near the shutter release, that moves left and right to alter how wide the view is. Quote Link to comment Share on other sites More sharing options...
jrman Posted July 30, 2020 Share Posted July 30, 2020 Are you sure it isn't a reverse rotation prop? Quote Link to comment Share on other sites More sharing options...
John Tee Posted July 30, 2020 Author Share Posted July 30, 2020 jrman. Thats the query it is a reverse prop Dennis. As you say the leading edge is on the table and that is the rear face of the hub. So the engine is in front of the hub as shown, this is the face I would normally put against the prop driver. I may be misleading you on the camera setting. It is not the width of the picture but the resolution - number of pixels used to make up the picture John Quote Link to comment Share on other sites More sharing options...
jrman Posted July 30, 2020 Share Posted July 30, 2020 It looks like a tractor prop for a reverse rotation engine. I don't think it's a pusher prop. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 30, 2020 Share Posted July 30, 2020 Pusher prop, turns CounterClockwise Leading edge is on the table, and boss upwards, where prop nut goes Your boss shows the back Here is a CCW Pusher prop Quote Link to comment Share on other sites More sharing options...
John Tee Posted July 30, 2020 Author Share Posted July 30, 2020 I bought 2 of these as counter rotation. I'll go down the shed later and reread the packaging. What you say jrman makes sense but I've never heard of such a propellor in over 50 years of modelling. Denis . that is what I would have expected. I will return later. Thanks for your inputs. John Quote Link to comment Share on other sites More sharing options...
John Tee Posted July 30, 2020 Author Share Posted July 30, 2020 Looks as if you are right. I ordered these props as counter clockwise but seem to have misread the details. I am surprised that the model shop had any in stock let alone two. Will have to reorder and make sure I get the right ones this time. Thanks for your help. I took the R/P to mean counter clockwise. Can't see why anyone would want a reverse pitch on a normal engine and how many reverse running engines are there. John Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 30, 2020 Share Posted July 30, 2020 Took me ages John T, to suss out CCW and CW props for models I went through a 10 year cannard phase before reliable lightweight electric set ups became available And most lads in most shops did not fully understand what they were selling at the time as it was niche Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted August 1, 2020 Share Posted August 1, 2020 Posted by John Tee on 30/07/2020 20:53:38: .... Can't see why anyone would want a reverse pitch on a normal engine and how many reverse running engines are there. John John, Back in the days when engines had bolt-on front crankcase bearings it was possible to reverse the rotation of an engine by rotating the front housing by 90°. This made it possible for a normal prop to be used in pusher configuration. A. Quote Link to comment Share on other sites More sharing options...
John Tee Posted August 1, 2020 Author Share Posted August 1, 2020 Andy that does ring a vague bell from long ago john Quote Link to comment Share on other sites More sharing options...
wingcoax Posted August 2, 2020 Share Posted August 2, 2020 John, I have recently received 2 3-blade "pusher" props from a major UK model shop as spares. Looking at them after unpacking they are the same as yours. In the picture on the shops website it is clear they are Proper pushers, yet i received RP as you did. I am contacting the shop to let them know. Steve. Quote Link to comment Share on other sites More sharing options...
John Tee Posted August 2, 2020 Author Share Posted August 2, 2020 Steve, That's interesting maybe a more common problem than me misreading the script. John Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted August 2, 2020 Share Posted August 2, 2020 Pusher prop? Beware of any (even the slightest) contact when adjusting the needle. Due to the angle of the blade being reversed, the normal warning tap on the knuckle or hand if you get to close is transformed into something akin to a swipe from a butcher's cleaver. I can still clearly see the scars from two encounters with a pusher prop on a little Veco 20 from over 40 years ago. It was only after applying a bandage to my left hand to match the one on the right one that I realised what was happening... Quote Link to comment Share on other sites More sharing options...
John Tee Posted August 2, 2020 Author Share Posted August 2, 2020 Steve. Just checked my order reciept and the web site, Numbers for the prop recieved and ordered match but the picture on the web page shows the hub as normal not reversed as mine is. May have to get back to them although I have damaged one as below. Martin. I have found that out the hard way. In a way I was lucky in that my finger went in to the prop arc from the tip not the side. I have now got a badly chewed up finger tip and no nail with a slit from tip almost to the palm - not too deep but deepest by the nail. Also lucky in that in the two weeks since I did it, it has healed well despite being diabetic which slows the healing process. If I had gone into the prop disc I would have lost a couple of fingers I'm sure. Another thing about a 3 blader is that you get an extra whack per rev. John Quote Link to comment Share on other sites More sharing options...
wingcoax Posted August 16, 2020 Share Posted August 16, 2020 John, I have spoken to someone in the trade and he says that they are the same thing. I cannot see that, in that the airfoil on the blade would be wrong as well. Still not heard back from the shop i bought them from. Steve. Quote Link to comment Share on other sites More sharing options...
John Tee Posted August 16, 2020 Author Share Posted August 16, 2020 Steve. I reordered my props and made sure the picrure tallied with what I expected and they have turned out be the same. I'm sure they will work ok it is just the hub is the reverse of the norm, The leading edge and aerofoil will be correct. It will still tighten up to the prop driver.I will try and see what happens when I can get the model noise tested. We only have 3 days/ week when we can run I/c motors. They came in a different packaging with the same logo as my picture above with the words R/P Pusher. John Quote Link to comment Share on other sites More sharing options...
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