_________________ “If things go wrong, don't go with them.” ..... ― Roger Babson “People say there are thousands of options we have in life. I say we have only two: we can either be happy or be unhappy.” ..... ― Pawan Mishra
Tue Nov 05, 2013 9:40 pm
Kolibri
Joined: Fri Oct 13, 2023 11:39 pm Posts: 139
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This was a very instructive video, thanks. I wish more kit companies did this and supplied the data to customers,
While I am not a CTL psycho, I do recognize the issue while understanding how difficult CTL is to achieve especially with people on board. Unless the thrustline is transecting their belly button, occupants will lower overall CG.
High thrustline gyros such as the RAF and Magni M24 Orion are typically slower due to additional rotor AoA (and thus drag) needed to counter the thrust's pitch down moment at higher speeds.
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Thu Apr 11, 2024 12:16 pm
Kolibri
Joined: Fri Oct 13, 2023 11:39 pm Posts: 139
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After flying my RAF before and after the addition of a Boyer H-stab (with 2° of negative incidence) the thrustline issue became more poignant to me. The RAF has a thrustline offset of 10-12" empty, and higher once fuel and occupants are added. Even with the Boyer H-stab, there was a momentary power-pitch coupling: increasing throttle pitched the nose down briefly before the H-stab force corrected it. While tolerable, I never liked the sensation.
The highest thrustline I know of is the Magni M-24 at 13.7".
The lowest thrustline of any 2-seat gyro that I know of is the Silverlight AR-1, about 4" above empty vertical CG, which was a deliberate improvement over its Apollo origins. https://www.rotaryforum.com/threads/wei ... st-1223238
Are there any center thrustline 2-seat pusher gyros in existence, even as empty? To get the prop so low would require either a very bent keel, or a very wide twin-boom. So far, no mfg. seems to believe the safety and performance benefits large enough to account for in design. Perhaps they're right....
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