***@earthlink.net (Richard Casady) wrote:
:On Sat, 21 Jun 2008 14:24:27 -0700, Fred J. McCall
:>***@earthlink.net (Richard Casady) wrote:
:>:On Sat, 21 Jun 2008 08:13:21 -0700, Fred J. McCall
:>:>It also had a real problem with the CG moving aft as fuel was burned.
:>:>This meant that if you got too low on fuel the aircraft might be
:>:>virtually unlandable because you had to come in so fast with such a
:>:The landing speed and angle of attack are determained by the weight,
:>:not the CG location. With an aft CG it takes more control deflection
:>:to keep the nose down, as the weight will push the tail down. You will
:>:run out of control authority, the reason you have to fly with the CG
:>:within certain limits.
:>And to get more control authority and more lift you fly faster and
:>with a higher AOA.
:>I didn't intend to give an aerodynamics lesson, Mr Casady. Just a
:>simple statement of fact.
:Unfortunately, your statement was not factual.
Unfortunately, your reading appears deficient.
:More lift is not whalt you want. You have to get rid of the lift, or
:you can't land the plane. With too much lift it won't come down.
:You increase the AOL during the landing to get the same ammount of
:lift at ever decreasing speeds.
In other words, more lift at a given speed.
:On the other hand, with too far
:forward a CG , you would be unable to raise the nose as you approached
:the ground. You would crash, nose gear first, in other words.
Let's try it one more time and see if you get it.
CG moves aft. You need to do a number of things to get down at that
point, foremost being you need to get the nose down far enough for the
gear to actually hit the runway before the big hot fragile thing at
the back does.
How do you do that? You need more control authority to force the tail
up and the nose down.
How do you get it? You stick a bunch of control surfaces out to apply
aerodynamic forces. This creates a shitload more drag.
To counter the drag you need to get more lift. You get that by
keeping your speed up, but there is a limit to how much of that you
can do and still actually land. So what do you do when you want to
land in that configuration, since you HAVE to drop the speed to
something that won't rip the gear off and shoot you off the end of the
You increase AOA (which leaves you with the same problem of the nose
Is it starting to sink in yet, Mr Casady?
"Some people get lost in thought because it's such unfamiliar