05-05-2012, 12:41 AM
I have a Gyrobee w/503/bbox, and ivoprop. i read somewhere that there is a procedure to adjust the prop at a certain rpm to get thrust set properly (measured with a scale). any input?
Altitude measured by attitude
05-05-2012, 03:48 AM
Here are a few things that might help you.
There are a couple tricks that will help with the Ivo from an IVO salesperson, none of this from Ivo... strictly his own advice.
Mark front and rear plates and number the blades. Always install it with the relationship between the plates and the blades the same way as the first time you assembled it. The reasoning behind this is that this way the knurl will fall into the same marks it left in the blades originally. The reason for re-torquing is not to crush the end of the blades, but to seat the knurl into the surface of the composite surface. The blades will "work" a little and the knurl will make it's mark on the surface of the blade.
Once there is a "female" imprint of the knurl in the blade, it shouldn't change anymore. As for re-torquing being a pain in the ass, all props that don't have a solid metal hub need to be re-torqued periodically, until they don't re-torque anymore. Wood props take a while to settle too. Same for composite over wood.
As for the tape, it does do a pretty good job of indicating movement. Had a couple customers that broke their tape until they went to the knurled plates. After that, no more broken tape.
Lastly, as with any assembled prop, or any prop for that matter, it's best to do a dynamic balance job of the whole assembly as installed in the aircraft, with the spinner and all if you can. This can quell vibrations and loads that might excite a problem over time. This is also another reason to mark and number the assembly.
Check the 503 with tail tied to a tree or something very solid, run the engine up to 6300 rpm in static on the tac. If it won't reach the 6300 rpm mark, then you have too much bite on the prop, (provided all else is right).
Adjust the prop to get 6300 rpm in static. It should then reach max hp in the air between 6500 to 6800 rpm. Never run engine over 6800, this is not good at all for the 503's. Ideal is around 6500 rpm in the air. If you were struggling with weight and trying to squeeze every last ounce of power you can get towards 6500 in static rpm but be advised with full throttle in the air you will be towards the redline.
With a Rotax 503 here are some pitch figures for various props and approximate thrust figures.
52" Ivo pitch 17* rpm 6500 Thrust 270lb
55" Warp pitch 11* rpm 6500 Thrust 291lb
60" Warp pitch 9* rpm 6800 Thrust 322lb
60" Ivo pitch 9* rpm 6800 Thrust 330lb
70" PwrFin Pitch 3* rpm 6500 thrust 350lb
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