Cubman
Member
Hi,
My design is to be a small single seat biplane of 510lbs gross weight and 108 sq feet wing area, with +4g and -2g as the Limit load factors, with speeds
Vs 38mph,
Va 76mph.
Vc 85mph,
Vd 120mph I realise these speeds are quite high for this gross weight, but I am just following Mr Stout's dictum, and I might get a bigger engine....
So is my understanding correct that loads used for the design of the structure would be my calculated limit loads based on the speeds and wing loading simply multiplied by 1.5, i.e whichever are the highest pull,push,bend,twist, or slice loads at points A,C,D,E,F and G on the Vn diagram?
Now for the silly questions:
So even though at Va/Vg and +4/-2g, where by design it won't be possible to exceed 4/-2g, I still use 1.5 times the Va/Vg loads for the structural design as normal? ditto for all the others; which brings up my next point.
I have a Vc gust load factor at gross weight of +4.4g and at an admittedly conservative minimum weight of 410lbs the situation worsens to +4.8g, and for negative gusts -3.45g. I knew that lighter airframes would be more sensitive to gusts:shock:
So, and here I think I know the answer, Do I still have to multiply the VF loads at 4.8g by 1.5 ( and have a nominally +7.2 ultimate bipe!)? 120 mph loads pale in comparison...
Thanks
Cub
My design is to be a small single seat biplane of 510lbs gross weight and 108 sq feet wing area, with +4g and -2g as the Limit load factors, with speeds
Vs 38mph,
Va 76mph.
Vc 85mph,
Vd 120mph I realise these speeds are quite high for this gross weight, but I am just following Mr Stout's dictum, and I might get a bigger engine....
So is my understanding correct that loads used for the design of the structure would be my calculated limit loads based on the speeds and wing loading simply multiplied by 1.5, i.e whichever are the highest pull,push,bend,twist, or slice loads at points A,C,D,E,F and G on the Vn diagram?
Now for the silly questions:
So even though at Va/Vg and +4/-2g, where by design it won't be possible to exceed 4/-2g, I still use 1.5 times the Va/Vg loads for the structural design as normal? ditto for all the others; which brings up my next point.
I have a Vc gust load factor at gross weight of +4.4g and at an admittedly conservative minimum weight of 410lbs the situation worsens to +4.8g, and for negative gusts -3.45g. I knew that lighter airframes would be more sensitive to gusts:shock:
So, and here I think I know the answer, Do I still have to multiply the VF loads at 4.8g by 1.5 ( and have a nominally +7.2 ultimate bipe!)? 120 mph loads pale in comparison...
Thanks
Cub
