Landing question

[FlyinHeel]

I have wondered for a while why doesn't the tail of a plane ever hit the ground right before touchdown when you are pulling back hard on the yoke? The tail of the PA28 I fly is normally 2 feet off the ground. It must come within inches of scraping. And if the tail did hit, wouldn't it cause a prop strike?

[1739T]

I am going to take a guess on this one having wondered the same thing myself.

First, I also fly a pa28 and mine, like yours has a device called a tail skid. Most pilots might think this is only used to tie the tail down but it does serve another function.

I would think to have "tail strike" during a normal landing you would probably exceed the angle of attack to keep you flying and you would stall forcing the nose over. The key word here is normal.

I often read NTSB reports and don't ever recall reading anything about a tail strike. There was however a NTSB report a few years ago concerning a modified twin commanche that was being used as an air ambulance. When loading the airplane the pilot loaded the patient and nurse in rear moving the CG so far aft that the plane came to rest on the tail skid. Unfortunately the force drove the tail skid through the airframe and caused damage to the horizontal stabilator control cables. Even more unfotunately the pilot did not find this out until after rotation. I don't remember the exact outcome but I believe it resulted in a multiple fatality accident.

[FlyinHeel]

Yes there is definite wear on the tail skid. I rent planes, so I'm not in them enough to say I scraped the tail, but the C-152s I trained in only had a metal loop for tie-down, no skid. I remember wear on that loop as well.

I would think it should be pretty evident if your tail hit the ground, especially if you were airborne, but not so much if you had the main gear on the ground.

[SeaAir]

The tail of an airplane can and does sometimes hit the ground - usually on landings or simulated soft field takeoffs. Most of the time it is not hard enough to cause any real damage, but just in case one step in my pre-flight check is to look under the tail and sight down the bottom of the fuselage looking for wrinkles in the skin or rivits that aren't lined up. If you see that kind of damage, don't go flying.

[canasdad]

FlyinHeel
You do manage to start a few interesting discussions.
Dragging your tail in trike aircraft is not uncommon. It occurs more often on landing in small aircraft, as the aformentioned soft field variety. You probably won't even notice due to the other noise in the aircraft. The skid/ tiedown point is there to prevent structural damage due to minor scrapes, and the ring on the Cessnas does that as well as the Piper skid. But even the heavy metal guys have a built in skid. With wear marks. Check it out the next time you taxi near one of the big boys. They tend to get nailed on takeoff, since they rotate suddenly at a high angle.

[FlyinHeel]

I remember now I have seen scrapes around the tip of the fuselage on the tails of the commercial jets. My question: why does this not cause prop strikes? If you were 6 feet about the ground on flare and wind shear hit your tail, would you not start flipping end over end?

[canasdad]

Naa- you won't flip. The drag (usually not very severe) acts as if you were pulling back on the tail skid. You'ld have to work hard to hit down with force enough to bounce due to the gradual change of force and the vector of the resulting drag. Actually bouncing the tail could cause the airplane to bend seriously unless this is a tail dragger. Think of the drag like a lead weight attached to your tail by a short rope to visualize it. When the skid loses contact with the ground, it quits dragging.
What will drop your nose (and your prop) is sudden deceleration that doesn't quit, such as standing on the binders hard enough to lock your wheels (mostly in tail draggers) or hitting an obstacle such as a snow berm.

[WESLEY]

I don't understand your question about prop strike. If you allow the tail skid to drag the ground, unless the strike to the tail was severe and caused the plane to loose control and pitch violently forward on the nose wheel(and nose gear was to callapse) I don't beleive you could have a prop strike.
My PA28 Turbo Arrow has the prop on the opposite end from the tail skid.
If you are in the habit of allowing your tail skid to drag, a little training and landing practice might help.
My next flight may have the same results; however, I don't expect to use the tail skid as a tail wheel.

[FlyinHeel]

My thinking was:
Hypothetically, if you are correctly balanced and coming in to flare, if your tail touches down and does not drag, it WILL (I think) send your nose forward. I guess it depends on whether the force on the tail is net up or down. My initial thinking was a tail strike would result in an upward force from the ground, resulting in a downward force at the front. Hence, the possibility of a prop strike.

[skid]

I think for visual purposes, the vertical component on the nose continues down when the tail cannot go down any further to increase angle of attack on wing. The kerplunk is just the result of the same momentum not being arrested by flaring. If it followed a full stall landing performed ten feet in the air, the nosewheel and firwall are often bent. On a taildragger, the cg is behind the gear so if the gear doesn't break or spread out enough to let the prop hit the ground, the prop can't hit the ground. Plus ground effect can soften the arrival of a wing on the verge of a stall to slightly above stalled. Dragging the tail doesn't really put a lot of stress on things unless the airplane is really dropped in.

[skid]

If you really want a discussion, is lift the result of low pressure on top of wing holding it up or higher pressure on bottom of wing holding it up? Symetrical wing airplanes fly, paper airplanes fly, the airfoil just makes for more efficient lift. Here's the question; airplane at an airshow doing aerobatics made hard pull, tail fluttered and horizontal stab and elevator departed airplane. Tail continued down causing extreme acceleration(g). Wing folded up like a butterfly. Were the wings forced back by the sudden blast of relative wind, or sucked back by the low pressure on top of wing?

[FlyinHeel]

Skid-
We had the lift discussion in my IFR ground school this week. My instructor, who's been flying since the '50s, is convinced the FAA teaches the lift principle wrong.

Like you, he used aerobatic flying as an example.

[skid]

I guess the real answer is that the pressure differential between top and bottom is the bottom line on creating "lift", but after flying aerobatics in a small biplane that was really nothing more than a seatbelt with a big motor, conventional thinking leaves a lot unanswered. I guess the best part of that little airplane was the sensation that throttle had more to do with airspeed than pitch attitude. It would go from 60 to 160 faster in level flight opening the throttle than it would closing the throttle and pointing it straight down. From 180 it would knife edge all the way down a 4000 ft runway without losing a foot of altitude. Once you slowed to about 120 you ran out of enough rudder to maintain altitude. The only thing making that fly was prop and momentum. I had some people tell me that it would snap like crazy from knife edge. But one wing has to be flying to snap or spin. It takes a LOT to make an airplane snap from knife edge. I don't know if much of this translates to safer point a to b, but all knowledge is good for something. I think the reason for alot of mishaps is the fact that most factory airplanes are so docile that it is hard to not get complacent or even to learn some very basic aerodynamics that aren't real obvious in something you can fly with your feet flat on the floor. Like the 60 degree, 2 g turn raising stall speed. Yes, if you're maintaining altitude, but the 1 g stall speed doesn't change with bank angle if you're not loading up the wing more than 1 G(descending turn). But you can't teach that in a syllabis because some might load the wing on a late turn to final by pulling the plane around. So for common (and prudent) teaching an airplane pulls 2 Gs and stalls faster if it is banked 60 dgrees. I'm not advocating changing flight training to include spins or the like as I think a little information is usually only dangerous. But discusions like this do add little pieces to a big abstract puzzle. Beside that, with all the time pilots spend hanging around an airport, what else are you going to talk about? Beats watching Operah.

[FlyinHeel]

From the NTSB reports, a tail-strike case:
http://www.ntsb.gov/NTSB/brief.asp?e...19X00608&key=1