Last Night in the TA, Deadra posed the question “Why does my plane roll when I pull up?” As it turned out he was in an FW190-D9, after asking and finding out that he was using a XBOX 360 game controller (Game Pad Controller) I ruled out Control Coupling (inadvertent Rudder input due to dead bands being set too low). So I asked him if he would like to join my plane for a demonstration. He joined and I spent some time showing and explaining to him the flight characteristics of a High Wing Loading Aircraft.
Better roll rate, higher speed attained due to less drag, increased effect of engine torque at stall speeds due to higher wing loading to name a few.
This got me thinking that it would make for good discussion in the BBS Help and Training section.
So I will kick it off and hope for some input from others on the subject. The question was posed. “Why does my plane roll when I pull up?”
The short answer is simple.
He was stalling the wings and therefore the engine torque took over inducing a counter clockwise rotation.(roll)
Why do some aircraft seem to be more susceptible to this occurrence than others? There are two main reasons that contribute to this.
Wing Loading and Engine Torque
Wing Loading: What is it?
Wing Loading is the total weight of the aircraft divided by the area of the wing.
Example:1. An FW 190 D-9 has a wing area of 197 sq. ft. and an average takeoff weight of 8.600 lbs. So…8.600 Divided by 197 = A Wing Loading (WL) of 43.65 pounds per sq.ft.
Example:2. A Supermarine Spitfire/ Seafire has a wing area of 240 sq. ft. and an average takeoff weight of around 7.000 lbs. This gives the Seafire a WL of around 29.1 pounds per sq. ft.
FW 190 D9 WL = 43.65 lbs. (High Wing Loading)
Seafire WL = 29.1 lbs. (Low Wing Loading)
(all deminsions and weights are aproximate but pretty close)
I suppose the simplest explaination would go something like this.
Wing Loading is the total amount of weight supported by each sq. ft. of wing area on the airplane. Therefore the smaller the Wing, the less lifting support for two aircraft of the same weight.
How does WL affect the Aircraft handling?
Wings generate lift basically by the motion of air over the wing surface. Larger wings move more air, so an aircraft with a lot of wing area relative to its weight (low wing loading) will have more lift at any given speed. Therefore, an aircraft with lower wing loading will be able to take off and land at a lower speed’s and require less power to keep it aloft.
It’s also important to remember that a larger wing is more resistant to wind.
When you try to roll the aircraft it has to push the wings against the air in order to roll.
Suppose you were to remove your wings while in level flight at full throttle. Or maybe someone kindly removes them for you
What happens? Right, the plane rolls extremely fast like a spiraling football thrown by a southpaw quarterback.
Engine torque is the reason for this.
This is why a Low wing loading aircraft, like a spitfire is less susceptible to the effects of engine torque than a High wing loading aircraft (like the FW 190 D9). As the engine tries spin the Aircraft the large wings counter act it.
So why build an aircraft with higher wing loading? In a word…well ok two words. Speed and Agility. Requiring less speed to keep an airplane aloft comes at a cost. i.e., increased drag. The larger wing usually dictates increased drag because of it’s mass resulting in lower maximum attainable speeds and less agility. Important note here: The wing size or mass alone isn’t the only factor that affects drag. The design of the Airfoil (shape of the wing) also has something to do with it as well. But that is another topic for another discussion.
Hmmmm wait a minute. If the higher wingloading Aircraft doesn’t have as much lift how ever will we keep it aloft? Well, Speed and thrust of course. Or in the words of Tim Allen, Power Baby!
The high WL mono planes of WWII actually provided a clue as to the design requirements of todays modern jet fighters. In short…With out the massive horse power and thrust, todays Jet Fighters would sink like a ROCK! In other words they fly on the thrust generated by the egine and not so much on the lift generated by the Airfoil / Wing design. Therefore most…not all High WL airplanes have more horse power and more engine torque.
So, “Why does my plane roll when I pull up?”
Because you stalled the wing or wings and the engine torque rolled the plane for you.
I hope yall will add your input.
