Conventional gear question - 3 point vs. wheel landings

[Rally]

Thats a straight Cessna 170 then. Rag wings? The A has metal wings no diahidral (sp) and small plan flaps. The B is pretty much like a Cessna 172 wing (actually it is one for the earlier c172).

 

[avbug]

I just found it interesting that the DC-3 manual seemed to state otherwise.

Don't forget that the DC-3 is a different airplane than an Aeronca Scout or J-3 Cub. Each airplane operates and must be operated a little difrerently. The principles largely are the same, but each airplane (indeed each serial number) will fly and act uniquely.

Consider the mode of braking...a simple cable and spring arrangement on some small conventional gear airplanes, vs. large hydraulic expander tube brakes on bigger equipment, Or disc systems. Each one has a different ratio of stopping power to the size of the aircraft, and each one has a different ability to either stop the airplane or stop wheel rotation...and some aircraft will solider forward with the wheel stopped while others will simply rotate around the axle. Then consider the proportion of the aircraft that's behind that axle, and what's pulling down, and where the aircraft balances (to include it's CG on any given day). Add to that the trim and tendency of the particular aircraft in it's loaded condition...will a sudden stop with the wheels cause it to go forward (ie, nose over)? Does the tailwheel down configuration lend to not only downward component to weight, but also an aft one? This means braking capability, as wel as an increased angle of attack and drag...tail down the airplane slows better than tail up.

A few years ago Charie Hilliard, a very respcted name in the aishow, aerobatic, and warbird arena was killed when his aircraft flipped during a brake application. Nobody is immune to the laws of physics, or their effects.

Think of a wheel landing as a balancing act. When you touch down on a wheel landing, you're balancing the airplane on the main gear; you can tip the airplane back, or you can tip it forward. If you touch down with excess speed, the rate at which you move the stick aft will determine if you stay on the ground; lowering the tail quickly (pulling back, quickly) can very easily bring you off the ground again. Pushing forward can pin the gear, tip you nose own, put the propeller closer to the runway, decreas your angle of attack even more, and spread the gear.

Adding brakes when pushing forward, or when balaning, can place you in a point of jeopardy, especially as when landing and the aircraft still being potentially light on the wheel, you're at a higher probabily of locking a tire. Now imagine a slight crosswind in which one wheel is lighter on the ground tha the other due to aileron input, and you have a potential for one wheel to lock and othe other to spin. If you apply pressure and find confidence as the airplane respond, you the apply more pressure, but with one wheel on the edge of locking up...you're setting yourself up for scrubbing a tire, a ground loop, or the start of a loss of control...including flipping the aircraf. Add runway contamination or other factors, and you could have a problem.

Braking may be necessary for some aircraft. It may be the only means of steering. I fly such an aircraft; no control over the tailwheel other than locking it, to steer...it's brakes, only. Last year I had a brake get very hot in 114 degree weather, while taxiing in a strong wind As I reached the end of the runway, I foud I could turn right but not left. I knew the brake would cool in the air, but the size of the airplane and the torque it produced meant that full rudder and some brake would have been required for the takeoff. With rough terrain surrounding the runway, wildly varying winds would have meant a high probability of loss of control; the brake was necessary both to steer initially (even with the tailwheel locked), and to counteract the torque (because full rudder won't handle it in that airplane, especially with a crosswind). In such cases where braking is required, know thy aircraft and take great care.

The DC-3 has several differences over a light conventional gear airplane, not the least of which is a big, thick wing section with it's own self-induced local airflow...power on each engine produces substantial lift, as well as affecting airflow over the vertical and horizontal stabs. You can lift the tail and turn the airplane in place if you really want to...though you probably shouldn't. You can also taxi clear with the tail in the air in calmer conditions, with judicious use of brakes...though again, there's no need.

Remember that the time from landing to tail down is your most vulnerable time. If you're wheel landing and keep that tail in the air, your rudder authority is decreasing, as is your elevator authority. If you have a crosswind and hold that tail up long enough, you may reach a point where you run out of rudder authority but the tail is still in the air being acted upon by the crosswind. If that happens and the tail starts to swing, if you can't get it down fast enough, you're already into a groundloop. If you touch it down while it's swinging, you may contribute to the groundloop.

During a wheel landing, once the mains are on the ground, I generally pin them there with some forward (but not excessive) stick, while I ensure I'm established and tracking straight, and then I retract the flaps while adding forward presure. As the aircraft settles and no amount of forward pressure will prevent the tail from coming down, I milk it down while taking care to ensure I'm tracking straight, transition my line of sight to the side of the runway, and start feeling very gently for the brakes. I have the benefit of reverse, so once the tail is down, I pin it there with aft stick (again, ensuring that I'm not going to go flying by adding aft stick...this is a very bad place to be; tail down, high angle of attack, and the mains come off again...possible in gusting conditions, and another reason I dump the flaps) and come into reverse. Reverse will kill additional lift and keep the airplane on the ground. It also blanks out the tail and eliminates any rudder control, or severely hampers it, so the airplane needs to be very much where you want it when you start), and then I'm steering with brakes.

The airplane is either an automotive machine, or an aeromotive machine. The transition between the two is what will get you into trouble. Make it as short, and as smooth as possible.

 

[Fearless Tower]

Thanks for the explanation, Avbug....makes much more sense now.

For Rally, the 170 I got my endorsement must be an A model since it has a metal wing and very small flaps.

 

[Rally]

And to contribute to Avbug at least the B model is one of those aircraft that you MAY need the brakes to contribute to the poor steering. Its routine to go from rudder stop to rudder stop on landing (at least in the B model). I was getting a check out in a Stinson one time from a non-instructor for insurance reasons (wierd situation) and I just about **** when he kept the tail in the air with a gusty winds and almost took the aircraft from him. Having the tail in the air (the elevator will keep the tail in the air on most aircraft way after you run out of rudder) is like being married and getting caught with the 16 year old next door when your wife comes home with your pants down. This is one of those times when you pay attention to Avbug! I agree completely, there can be a certain time with the tail in the air to the ground that you are a rider. You should never be a passenger in a a aircraft, EVER. Don't slam that tail down either, those springs on the tailwheel should be changed ever 500 hours lest it will break and take out a good portion of the tail.

 

[FL420]

Like others have said; it depends on the aircraft.

I usually 3 point both the Swift and the Stinson. I will wheel-land the Stinson in high winds then pin the tail by retracting the flaps. They are mechanical and I have fine control over the amount and rate of retraction. It has a large vertical fin and rudder so in very high winds I will land no-flaps and fly it all the way to the chocks. In CYS once I had to get a couple of linemen to chain it down while I kept it flying in the tiedown spot with the tail up. The winds were a fairly steady 50 knots.

The flaps on the Swift are electrically-driven and hydraulically-actuated. It was designed before the days of Human Factors engineering so the Landing Gear control is a lever that looks like a flap and the Flap control is a round knob that looks like a wheel. For that reason, plus the low wing and relatively high wing-loading with the shortened wingtips, I almost always 3 point it and don't retract the flaps on the runway.

 

[Launchpad]

Just to clarify, a DHC 3 is an otter and a DHC 2 is a Beav.....

<<I also flew the DHC-3 Beaver and I usually made wheel landings in that airplane.>>

I tried to make wheel landings with a low tail when I had a C-180. 3 points and wheel landing both have there place. Dumping the flaps on rollout is very common and a good way to get the weight off the wings and onto the tires. Tell the FAA to suck it.

Tail wheels are the weak point (of the 3), and shimmys are common and very hard on the whole tail assembly-

Good luck!

 

[nosehair]

The logic was that during a wheel landing, as long as the tail was still 'flying', you could apply significant braking without fear of nosing over. However, once the tail stopped flying and came down, you were at risk of nosing over if you applied too much brake.

Oh, now you're talking some serious tailwheel technique. Yeah, once you can wheel land with power and keep it powering down the runway, a long runway for this practice, and ease in light shades of brake while adding light shades of back pressure to keep it balanced on the wheels, and begin to ease off throttle and just the right amount of back pressure as you throttle back to firmly land the tailwheel as you brake to a stop. Takes lots of practice, and is best done in strong steady headwinds. Strong steady headwinds are good times to practice getting the tail up immediately on take off. Matter of fact, see if you can get the tail up with partial to full power and hold the brakes into a strong headwind. This is a good place to practice and find the balance between power and elevator and brake.

Don't be afraid to push the elevator forward. It takes quite a bit of nosedown to contact the surface.

I'm talking light singles, now; but while the airplane is parked, lift the tail up high enough to see how far down the nose needs to be for a prop strike.

 

[svcta]

Yeah, you can "walk" a cub around nicely with no real danger of a prop strike. No that one should, though. When I was doing tailwheel training in I would have the student run the length of the runway with the tail up to develop the technique of actually controlling the plane with the rudder. During normal t/o and landings they never really have to keep the thing going in a straight line while on the mains for more than a few seconds at a time. I notice that a lot of newbies tend to take advantage of the fact that most conventional gear a/c will fly with little ground roll and sort of bail themselves out by getting it in to the air as soon as they can. And that only makes for weakness in a critical area of the transition in my opinion. The high-speed taxi also helped people get the feel for the heel brakes in the cubs and you could also sort of introduce the concept of what the brakes will do to you(good and bad).

 

[con-pilot]

<<I also flew the DHC-3 Beaver and I usually made wheel landings in that airplane.>>

Oops, :0 , yes you are correct of course. The Beaver is a DHC-2.

(That will teach me to proofread prior to posting.)

 

[MauleSkinner]

Dumping the flaps on rollout is very common and a good way to get the weight off the wings and onto the tires. Tell the FAA to suck it.

You have to remember that the pilot population within the FAA that really knows much about tailwheel flying is probably lower than the non-FAA pilot population that does.

Which is why our local FSDO is allowing a DE to do a checkride to remove a conventional-gear limitation from a pilot's certificate, instead of doing an actual 709 ride

Fly safe!

David