rogerh12
08-02-2011, 07:29 AM
Howdy all;
While at Oshkosh (which was great), I did some talking to other Kitfox guys and had a realization. A while back, I proposed building a Kitfox Model 4-1200 with a gross weight of 1250 lbs. I justified this because the current load specification of an ultimate wing loading of 7200 LbS (1200 lbs x 6 G’s) would become an ultimate wing loading of 5.76 G’s at a gross weight of 1250 Lbs, which still placed the kitfox within the “NORMAL “ category for wing loading as outlined in FAR Part 23. For example, if this was a certified plane and the Kitfox was designed to comply with the FAA specification for NORMAL category, it would need to operate at 3.8g’s, and be built with a safety factor of 1.5 (as outlined in FAR 23.303), which corresponds to a ultimate positive G load of 5.7. As mentioned above, at a gross of 1250 Lbs, the model 4 would have an ultimate wing loading of 5.76 G’s. However, having said all that, a 1250 Lbs gross kitfox was kind of boarder line. But now I have a better idea:
I noticed that the model 4 speedster has a shorter wing, and that it is rated with an ultimate load limit of 9 G’s at an operating gross weight of 950 Lbs (for aerobatics). This corresponds to an ultimate wing loading of 8550 lbs. If I figure on using the shortened speed wing, the kitfox 4 at a 1250 lbs gross would now have a ultimate positive wing loading of 6.84 G’s, which places it well with within the NORMAL category with a safety factor of 1.8. In fact, with this level of safety factory, the kitfox 4 COULD be operated in the UTILITY category of 4.4 G’s, and still have a 150% safety factor.
Of course other changes to the airframe would be needed, most notably the landing gear.
What do you think, does this case hold water?
Roger
While at Oshkosh (which was great), I did some talking to other Kitfox guys and had a realization. A while back, I proposed building a Kitfox Model 4-1200 with a gross weight of 1250 lbs. I justified this because the current load specification of an ultimate wing loading of 7200 LbS (1200 lbs x 6 G’s) would become an ultimate wing loading of 5.76 G’s at a gross weight of 1250 Lbs, which still placed the kitfox within the “NORMAL “ category for wing loading as outlined in FAR Part 23. For example, if this was a certified plane and the Kitfox was designed to comply with the FAA specification for NORMAL category, it would need to operate at 3.8g’s, and be built with a safety factor of 1.5 (as outlined in FAR 23.303), which corresponds to a ultimate positive G load of 5.7. As mentioned above, at a gross of 1250 Lbs, the model 4 would have an ultimate wing loading of 5.76 G’s. However, having said all that, a 1250 Lbs gross kitfox was kind of boarder line. But now I have a better idea:
I noticed that the model 4 speedster has a shorter wing, and that it is rated with an ultimate load limit of 9 G’s at an operating gross weight of 950 Lbs (for aerobatics). This corresponds to an ultimate wing loading of 8550 lbs. If I figure on using the shortened speed wing, the kitfox 4 at a 1250 lbs gross would now have a ultimate positive wing loading of 6.84 G’s, which places it well with within the NORMAL category with a safety factor of 1.8. In fact, with this level of safety factory, the kitfox 4 COULD be operated in the UTILITY category of 4.4 G’s, and still have a 150% safety factor.
Of course other changes to the airframe would be needed, most notably the landing gear.
What do you think, does this case hold water?
Roger