FAQs

We've Got Answers....

In general each of the flights or adventures will be self-describing. There are times, however, when certain characteristics of aviation science is beyond the scope of the flight briefings. In some of those cases there is a short answer given here, and usually links to more complete information will be given.

What does the term "density altitude" mean?

By "density altitude" we mean the altitude that is seen by the aircraft based upon the density of the atmosphere where you are. One indication of "density altitude" is seen when you change the barometric pressure setting on the altimeter. The altitude changes when this changes. Density altitude is significant when flying at higher actual altitudes. It is most noticeable in longer take-off runs. This may mean that an airport where you could land with a particular weight might be one you cannot takeoff from at the same weight! Density altitude effects are reduced by cold, and thus early morning or late afternoon takeoffs will sometimes compensate.

The density of the air is affected by altitude, temperature and, to a lesser extent, humidity. As the air warms up it becomes less dense, and thus it acts as if you were at a higher altitude than you would normally think you are. As air cools it becomes denser, and the aircraft acts as if it were at a lower altitude.

From a pilot's standpoint, the effects of density altitude are seen in:

	Increased takeoff distance
	Reduced rate of climb
	Increased true airspeed on approach and landing (with the same IAS)
	Increased landing roll distance

Why does the engine quit running when I'm at higher altitude airports (such as Avion or Flagstaff)?

Usually this is caused by having too rich a mixture for the altitude. This can result in the engine not getting enough oxygen to continue burning fuel, or it can result in wet-fouled plugs which will also cause ignition to terminate.

Do I have to fly the IFR flights as IFR or can I fly them VFR?

While it is certainly possible to fly all the flights VFR that would defeat the purpose of the adventures. Many of them are flown in clouds and require knowledge of how to shoot an ILS approach. Your ticket will not be pulled for flying VFR in IMC conditions, but it would be better to develop the skills and knowledge necessary to get the most from these adventures.

What are the "four forces"?

This term generally refers to the four "forces" that act on an aircraft. They are not forces in the generally accepted meaning, but rather are characteristics of numerous forces. The four are generally stated as lift, drag, gravity, and thrust. Lift and gravity affect the altitude of the aircraft while thrust and drag affect the speed of the aircraft. Of course, these forces all interact dynamically during flight so that you can climb, descend, fly straight-and-level or turn.

Lift: Most people have learned (incorrectly) that lift is a function of the curvature of the wing such that the Bernoulli principle dealing with pressure gradients causes lift. While this is certainly a factor, it is not the sole factor in lift. Newtonian mechanics also applies here, and is what accounts for things like downdraft. for more on this, see Flight Testing Newton's Laws. Another interesting site is: How Airplanes Fly: A Physical Description of Lift

Gravity: Gravity is a property of matter. The more matter one has, and the denser it is, the more gravity there is. Gravity is what "pulls" is toward the (gravitational) center of the earth. This is the force that will ensure our return to the ground should our aircraft lose power.

Drag: Incorporating several aspects of mechanics into a single term can lead to oversimplification. In general, however, "drag" refers to the aircraft's "resistance to movement in the air." There are additional factors on the ground (resistance to rolling in the tires, inertia, etc.) that are generally not considered part of the equation in the air.

Thrust: This is the force generated (usually internally) by the aircraft to overcome drag and allow the plane to move. For gliders this is initially applied by the two plane, and then is supplied by gravity and inertia (that is, the sailplane trades altitude for distance). For more on this see: How Things Fly

For more on this topic see What Makes an Airplane Fly.

I've heard the term "tail stall" -- what does that mean?

Good question! An airplane has two centers of gravity, one horizontal and one longitudinal. That is, there is a point down the length of the fuselage where the airplane could rotate about its center, and another that runs though the plan along the same direction as the wings. This CG, in fact, is one that we concern ourselves with when loading the airplane, the other when burning fuel from one wing tank or the other.

In this case, we're concerned about "loading." As you may know, the main wings lift the aircraft. The tail actually provides "negative lift" -- this is, it pushes the back of the plane down. In fact, if you watch the elevators when you pull back on the yoke or stick, you'll find that they deflect up pushing the tail further down so that the thrust factor can pull the aircraft higher. Without the tail to push down, the aircraft would rotate around this load CG and point the nose toward the ground.

Tail stall refers to the failure of the tail to provide this downward lift just as wing stall (or, normally, just stall) is a failure of the wing to provide lift. Tail stall normally occurs as a result of ice buildup.

Recovery from a tail stall is exactly the opposite of recovery from a wing stall. To recover from a tail stall reduce power and gently pull back on the yoke or stick. The object here is to get the air flowing normally over the tail to re-establish the necessary lift.

Do you have other adventures planned?

Yes! As we develop ideas for adventures we will develop them and put them on the web site. Ideas for new adventures are always welcome.

If you have other questions, please contact us.