We visited the project of a local ultralight pilot the other day. He is building a set of Wittman wingtips for an RV-3 that belongs to a friend of his. The new wingtips are composite construction, and will add maybe 1.5 to 2 feet span on each wing. His intent is to make the RV-3 LSA compliant. I don't intend to discuss the LSA rules in this thread, though I think he will have problems there too. My concern is in the aerodynamics and structural issues.
I expressed my concerns to him that there has been no analysis of either aerodynamics or structure for this mod. He has not considered matters such as changes in airflow, wingtip stall, stability/controllability issues that might arise due to a larger wing with the original tail size, or structural issues due to increased bending moments caused by a longer span.
In his opinion, Steve Wittman was a genius, and if Wittman said his tip was good for Wittman's planes, then it is good for all planes. He fully expects to gain the same performance advantages without any negative effects, and is not willing to hear otherwise.
Now, I don't want to take away from Steve Wittman, because he was a truly talented designer and builder, but this form of blind hero worship is setting him up for possible failure and potentially life threatening risks.
has anyone else here dealt with this type of issue? If so, how did you convince them that they were travelling down an unmapped road? At this point, I think my best option might be to find the RV-3 owner and share this concern with him. It won't make me any friends with the wingtip builder and his circle of friends, but...
Bruce
I expressed my concerns to him that there has been no analysis of either aerodynamics or structure for this mod. He has not considered matters such as changes in airflow, wingtip stall, stability/controllability issues that might arise due to a larger wing with the original tail size, or structural issues due to increased bending moments caused by a longer span.
In his opinion, Steve Wittman was a genius, and if Wittman said his tip was good for Wittman's planes, then it is good for all planes. He fully expects to gain the same performance advantages without any negative effects, and is not willing to hear otherwise.
Now, I don't want to take away from Steve Wittman, because he was a truly talented designer and builder, but this form of blind hero worship is setting him up for possible failure and potentially life threatening risks.
has anyone else here dealt with this type of issue? If so, how did you convince them that they were travelling down an unmapped road? At this point, I think my best option might be to find the RV-3 owner and share this concern with him. It won't make me any friends with the wingtip builder and his circle of friends, but...
Bruce
