I have been building the carbon fiber and Aluminum versions. They are a bit heavier than we expected, but that is due to real materials. We certainly will take out some of the fat in future revisions, but I think that the issue here is approach speed. You bunch of sissy girls. These planes are UAS, unmanned means the computer should be doing the work to bring the plane in on glide path. I hope our spars are strong enough for the cut the power approach.
What the heck am I talking about? Nope, never been asked that in polite company either. Wing loading is a relative measure that comes out of the basic low-speed aerodynamics of any fixed-aircraft. In some ways, it is a measure of the relative performance of a device with respect to constant thrust. It is most easily expressed as the mass of the aircraft divided by the wing area.
This essentially describes how strong the pressure difference must be between the surfaces to keep the plane in the air. Considering that the higher the wing loading, the larger the drag due to lift turn will be. This will change the trim characteristics of the plane in cruise and require more thrust to keep the plane above stall. Any F-4 or F-15 driver will tell you that more thrust is the answer to everything.
"The critical limit for bird flight is about 5 lb/ft² (25 kg/m²)[3]. An analysis of bird flight which looked at 138 species ranging in mass from 1x10-2 to 10 kg, from small passerines to swans and cranes found wing loadings from about 1 to 20 kg/m2[4]. The wing loadings of some of the lightest aircraft fall comfortably within this range. One typical hang-glider (see table) has a maximum wing loading of 6.3 kg/m2, and an ultralight rigid glider[5] 8.3 kg/m2." - wikipedia
The wing loading also changes the stall speed. If you have to use forward speed to generate enough lift for a given flight regime, you have to go faster to balance the weight of the aircraft with the lift generated. In a flying wing, you cannot just pick the nose up, roll control has to be gentle. The old adage "Little planes add flap, big planes add power" is our friend. If you were interested the effect of wing loading on stall speed is expressed as the following.
v^2 is the stall speed
g is the acceleration due to gravity
Ws is the wing loading, mass/wing area
rho is the density of air
CL is the coefficient of lift of the net wing
Another interesting equation, is the rate of climb. This is just a force balance between the net acceleration, lift generated and the weight of the device.
ac is the climbing acceleration
Ws is still the mass wing loading
vc is the new airspeed
rho is the density of the free stream air
CL is the coefficient of lift of the net wing
g is the acceleration due to gravity
The wing loading term is in the denominator, so if you want to climb faster you need to lower the wing loading, or increase speed. Increasing the speed is way more fun than having gossamer wings. More Power!
We are not so bad, we are in the 23-35 kg/m^2 range for our wing loading depending on the equipment load out. Less than a some gliders. We however, cannot skimp on pimping the power plant. As if we would do that.
Aircraft Wing Loading (kg/sq m)
swan 10
Buzz Labs Schoolgirl UAV 23
Nieuport 17 38
Cessna 152 51
B-17 190
F-104 514
A380 who cares, it is an airbus
B747 740
We already know you can do your approach at a reasonable speed, but why? Sensible approaches are for people who do not think that 10 ft/s sink rates are for roller coasters. Land It Like a Man, Full Throttle and Both Hands on the Stick. Or, just let the autopilot do it, it can tell how far it is from the ground and cut the power at stall two inches off the ground.
If the women don't find you handsome, they ought to find you handy!
