How does stall speed vary with cg

Your email address will not be published. Notify me of follow-up comments by email. Notify me of new posts by email. Keep those questions coming! Share this: Facebook. Leave a Reply Cancel reply Your email address will not be published.

Aircraft with propellers will have an additional effect caused by the propeller slipstream. The most important factors affecting this relationship are engine type propeller or jet , thrust to weight ratio and inclination of the thrust vector at C LMAX. Figure 7. The slipstream velocity behind the propeller is greater than the free stream flow, depending on the thrust developed. Thus, when the propeller aeroplane is at low airspeeds and high power, the dynamic pressure within the propeller slipstream is much greater than that outside and this generates much more lift than at zero thrust.

The lift of the aeroplane at a given angle of attack and airspeed will be greatly affected. If the aircraft is in the landing flare, reducing power suddenly will cause a significant reduction in lift and a heavy landing could result.

The typical jet aircraft does not experience the induced flow velocities encountered in propeller driven aeroplanes, thus the only significant factor is the vertical component of thrust, Figure 7.

Since this vertical component contributes to supporting the weight of the aircraft, less aerodynamic lift is required to hold the aeroplane in flight. If the thrust is large and is given a large inclination at maximum lift angle, the effect on stall speed can be very large. Since there is very little induced flow from the jet, the angle of attack at stall is essentially the same poweron as power-off.

When you look at the diagram below, what you really see is that weight and tail down force both need to be balanced out by lift. Essentially, lift needs to equal weight and tail down force. When you create more lift, you create more induced drag as well. So as you can see, when your CG is forward, you need more tail down force, and more lift. You generate that extra lift by increasing your angle of attack, which in turn increases induced drag.

Before you go throwing everything possible into the baggage compartment, consider this: while having an aft CG definitely improves performance, in most light aircraft, the difference will only be a few extra knots of airspeed, and a few extra feet-per-minute of climb rate. While it doesn't make a huge difference, an aft CG might help you get to your destination a few minutes early on your next long cross country.

Become a better pilot. Subscribe to get the latest videos, articles, and quizzes that make you a smarter, safer pilot. Colin is a Boldmethod co-founder, pilot and graphic artist. He's been a flight instructor at the University of North Dakota, an airline pilot on the CRJ, and has directed development of numerous commercial and military training systems. You should have forces just like in the picture above.

Slowly move your two pointer fingers together with the pencil in the middle. At some point, the thumb will no longer be required to maintain stability.

Without using your thumb now, move your pointer fingers away from each other. The pencil should rotate very easily out of your hand. There are some airplane where the CL is forward of CG but to solve the stability issue, there is a canard which provide a nose-up force to keep the nose from rotating. I have read, that airplanes with canards are difficult to stall due to the fact the canard will stall before the main wings. First of all, as answered in this question , centre of pressure of the whole aircraft and centre of gravity must coincide for quasi-steady flight.

Since the 1G stall speed, by definition of Part 23 and 25 regulations, is essentially quasi-steady, this holds true. While the maximum wing lift is a fixed number for a given Mach and Reynolds number, the total aircraft CLmax can vary due to tail lift contribution. As the CG moves forward, CLmax decreases due to increased tail down force for trim. The following relationship, found in Advisory Circular C , roughly captures the influence of CG on maximum lift coefficient, which you can use to compute the stall speed:.

Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more.