FlyingMonkey Posted October 18, 2021 Report Share Posted October 18, 2021 Hello... I have to recalculate my W&B for my new E-Props propeller. My factory W&B sheet does not include the prop as a separate item, I guess it was included in the basic airframe calculation. Does anybody know the CG position/Arm of the prop in relation to the datum (wing leading edge) so I can change the prop weight and recalc the new CG? The Battery is at -22.83", so I'm guessing the prop is somewhere like -40" to -44". Thanks! Quote Link to comment Share on other sites More sharing options...
Madhatter Posted October 18, 2021 Report Share Posted October 18, 2021 With the aircraft reasonably level attach a weighted string to the leading edge, mark the floor. Then do the same at the middle of the prop assembly. Then measure the distance with it parallel to the fuselage . Quote Link to comment Share on other sites More sharing options...
Anticept Posted October 18, 2021 Report Share Posted October 18, 2021 The propeller is in your equipment list. It will have the weight and the location. Mine for example (do not use!) shows -49.6 inches and 13.6 lbs. After you install the new prop, don't forget to update it for your ease in the future. I don't think equipment lists are required on E-LSA. Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted October 18, 2021 Author Report Share Posted October 18, 2021 18 minutes ago, Anticept said: The propeller is in your equipment list. It will have the weight and the location. Mine for example (do not use!) shows -49.6 inches and 13.6 lbs. After you install the new prop, don't forget to update it for your ease in the future. I don't think equipment lists are required on E-LSA. If by "equipment list" you mean the factory CG sheet with the equipment list down the right side...then no, my prop is not on it. Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted October 18, 2021 Report Share Posted October 18, 2021 I would do as Madhatter said. I would probably drop one from the leading edge on both sides and snap a chalk line between. The one for the tail and the center of the firewall, but extended beyond the prop. Then finally one from the fore and aft center of the prop. Measure from where the centerline crosses the leading edge line to the propeller line and you have your number. The other option is to defuel, level, and weigh the airplane, and get a new actual empty weight and CG. Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted October 18, 2021 Author Report Share Posted October 18, 2021 19 minutes ago, Tom Baker said: I would do as Madhatter said. I would probably drop one from the leading edge on both sides and snap a chalk line between. The one for the tail and the center of the firewall, but extended beyond the prop. Then finally one from the fore and aft center of the prop. Measure from where the centerline crosses the leading edge line to the propeller line and you have your number. The other option is to defuel, level, and weigh the airplane, and get a new actual empty weight and CG. That sounds like the best way to get an accurate number. I'm not doing an actual weighing unless it becomes legally required for some reason. That seems to always cost people useful load. Thanks guys. Quote Link to comment Share on other sites More sharing options...
Anticept Posted October 19, 2021 Report Share Posted October 19, 2021 It also costs a good chunk of change... those scales aren't cheap! Quote Link to comment Share on other sites More sharing options...
GlennM Posted October 20, 2021 Report Share Posted October 20, 2021 Roger has changed lots of props. He should know the value. Quote Link to comment Share on other sites More sharing options...
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