john stones 1 - Moderator Posted February 21, 2022 Share Posted February 21, 2022 More tilt needed ? Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted February 21, 2022 Share Posted February 21, 2022 Shame. Those blades don't look to be spinning very fast.... a change of pitch needed ? Hopefully someone with more knowledge than me will be along to help out! Good luck. Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted February 21, 2022 Author Share Posted February 21, 2022 Tried more pitch no Autorotation. I think the bear foam blades are too draggy so I will make a selection of blades to see which will work beast, Balsa wood, foam covered with tape to give a smooth surface and a built up blade a bit like a long thin wing. cheers for the comments guys. Steve. 2 Quote Link to comment Share on other sites More sharing options...
Richard Harris Posted February 21, 2022 Share Posted February 21, 2022 Steve, I was just jumping off my seat trying to get it to lift off! I'm with John, more rearward tilt possibly needed. 2 blades will need at least 3 degrees more rearward tilt than 3 blades and tio weights. Also, theory says 20 degrees is the minimum rearward tilt to start autorotation so you will need this when the airframe is sat on its feet. Before making new blades it may be worth testing to see if they will spin up in a light breeze held in your hand? At least that will confirm whether the blades are worth perusing as they are. Have you got a close up photo of hub and blade mounts you used? Rich 1 Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted February 21, 2022 Author Share Posted February 21, 2022 Hi Richard, I thought about trying a little more rearward tilt on the head unfortunately some smashed into it before I could make those adjustments. Luckily only one blade was damaged a split across the foam blade halfway so decided to call it a day. Cheers for the advice ?? Steve. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted February 22, 2022 Share Posted February 22, 2022 From what I remember about my Atoms the LE needs to be very sharp at the lower edge, no rounding off, which you are unlikely to get with foam by itself but easier if it is balsa which will also add some of the required weight. You can sometimes compensate for rounding by packing the blades up at the rear to reduce the angle of attack which allows them to spin up much more quickly. There should be much more information on the Atom build blog. Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted February 22, 2022 Author Share Posted February 22, 2022 3 hours ago, Martin McIntosh said: From what I remember about my Atoms the LE needs to be very sharp at the lower edge, no rounding off, which you are unlikely to get with foam by itself but easier if it is balsa which will also add some of the required weight. You can sometimes compensate for rounding by packing the blades up at the rear to reduce the angle of attack which allows them to spin up much more quickly. There should be much more information on the Atom build blog. Hi Martin. A good atom special type aerofoil has been achieved by adding a balsa leading edge which may not be visible by these pictures alone. Steve 1 Quote Link to comment Share on other sites More sharing options...
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