Just a couple of additional thoughts.
As Rich suggested, we do have pretty good success with high wind landings out here on the left coast. Some of the reasons for that success have been touched on above, the cutoff loop and proper landing gear location. There are, in addition, some other important things to know. Here's a pretty complete primer on how we approach the problem.
IMPORTANT: NOTE THE FOLLOWING DISCUSSION IS PRETTY MUCH PERFECT FOR HARD SURFACES BUT USING IT ON A BUMPY GRASS FIELD COULD RESULT IN DAMAGE BECAUSE YOUR TOUCH DOWN SPEED WILL BE MUCH HIGHER THAN "NORMAL".
The cutoff loop works with a "hard tube" tank; i.e. a non clunk. The "secret" is that when the tank gets close to empty any sustained positive or negative "G" load will draw the fuel to the (in the case of an inside cutoff loop) bottom back corner of the tank and uncover the fuel pick up tube centered in tank. The secret is generally to merely sustain the positive g for a long enough period of time that the fuel line is pretty much full of air and the engine flames out just as if the tank was totally out of fuel. Bill suggested one normal loop followed by a tight one. I personally think one large loop started at about 30 degrees elevation works best because when you get to the top of the loop not only the g loads but gravity are working to get the fuel away from the pick up tube. Listen intently to your engine and learn what it sound like when it is getting to that point. Usually it will be a subtle but noticable increase in revs that tells you the tank is about dry. I hear the first hint of that and go two additional full laps and then do the loops coming into the wind on the third lap. This is reliable about 90% of the time. If the needle setting is leaner than normal due to the high winds and a need for a little more "zip", I'll go an additional couple laps.
The cutoff loop should be started to the flyer's left of downwind (for the vast majority who fly CCW; the opposite for you sinister, backward types). When doing a loop into the wind this way the high winds will actually accelerate the ship around the loop. This does two good things. First it increases the g loads and helps pull the fuel away from the p.u. tube; second it gets the airplane really moving (much more than you will ever be able to accomplish be whipping in a high wind). This "afterburner" effect is what makes the classic west coast high speed landing possible in well under a lap, by providing the energy to penetrate back into the wind and give the flyer very positive pitch control while doing so.
This energy and positive control should be used by the pilot to touch the airplane down with precision somewhere on the part of the circle between where the wind is directly on the airplanes tail and prior to dead "downwind" with respect to the pilot. That's a quarter lap or so that will be ideal. It is valuable but not essential that the touchdown occur prior to coming back into the wind. If the speed is still up it is possible but harder to make a clean touch down. There should be no attempt to make a full stall landing, trust me, at the speed you're going it ain't going to stall but will, instead climb back up, ruinning your landing points. Instead, think of flying the airplane onto the ground (a very common practice in full size aircraft up to and including B747s in high winds). You will find you can make surprisingly good, smooth touchdowns.
IMPORTANT: Continue "flying the airplane" after touchdown until it comes to a stop. Don't simply jam down control because at these speeds you might well pitch the ship up on it's nose. Instead, as the speed decreases apply increasing down control until it stops rolling. Just prior to coming to a stop return the controls to neutral because you will no be at the mercy of whatever wind gradient and direction exist at the point it stops. Large control surface deflections expose the ship to potential flip overs just sitting still in high winds. With the controls at neutral there is much less risk of doing so.
Landing gear: Two really important things here. First, the point at which the wheels touch the ground with the airplane level needs to be within a fraction of 15 degrees forward of the Center of Gravity. Don't ask me why, ask Wild Bill who told us this "essential" piece of information 40 or so years ago. Trust me, it is "magic". When the wheels meet the tarmac at this point you can essentially "fly" the airplane while it is on the ground ... or, when it is taking off or landing. Much forward of that point and the tail will generally fall when the gear touches down (and you "will" go airborne again at the speeds we're talking about.
Second important thing about landing gears. You need brakes. Don't laugh, I'm serious. I always install an "O" ring between the wheels and the wheel retainer and cinch the wheel pretty snuggly against the "O" ring. The wheel shouldn't "spin" at all when you try to spin it. Exactly how snug will depend on the weight of your ship. The proper "snugness" will result in little or no observable change in the take off roll but will have a significant effect on the length of the landing roll. That's what you want to avoid the extended roll out back into the wind which exposes the lazy pilot (the guy who thinks he's got the landing wired ... don't ask me how I know this) to the dreaded "omigod it's back in the air again" experience.
By the way, that little bit of drag on the wheels helps in making a smooth wheel landing because it tends to pitch the model just a touch forward which helps keep the angle of attack from increasing and exposing you to a bounce if you touch down a bit hard. ANother benefit, if you make a really good touchdown you can't even hear the wheels spin up. No clanking or whirring of plastic on steel. If the judges have to guess where the airplane touched down, they've got to be impressed and will score accordingly.(CAVEAT: DON'T OVER DO THIS BRAKE BUSINESS. YOU SHOULD BE ABLE TO PRETTY FIRMLY PUSH THE AIRPLANE FORWARD ON THE GROUND AND HAVE IT ROLL TWO OR THREE FEET BEFORE STOPPING AND IT CERTAINLY SHOULDN'T NOSE OVER WHEN DOING SO. ALSO, BE SURE IT TRACKS STRAIGHT AHEAD WHILE DOING SO. OBVIOUSLY, THE FRICTION ON THE LEFT AND RIGHT WHEELS SHOULD BE AS CLOSE TO SYMMETRICAL AS POSSIBLE. BE MODERATE!
One last thing that is very important.
AIRPLANE TRIM HAS A GREAT DEAL TO WITH HANDLING HIGH WINDS ON LANDING. FIRST AND MOST OBVIOUS, THE WINGS NEED TO BE LEVEL OR, IF NOT, THE OUTBOARD WING MUST BE DOWN WHILE UPRIGHT. IF YOUR SHIP FLIES WITH THE OUBOARD WING HIGH IN UPRIGHT IN LEVEL FLIGHT, YOU'RE GOING TO HAVE TROUBLES IN THE GLIDE ON THE UPWIND SIDE OF THE CIRCLE.
ALMOST AS IMPORTANT IS CG LOCATION AND TRIM IN THE "PITCH AXIS", NOSE UP AND DOWN. YOUR AIRPLANE CAN NOT BE TAIL HEAVY! THE ABILITY TO WHIP REQUIRES A LITTLE PILOT SKILL, YES, BUT NO MATTER HOW SKILLED THE PILOT IS THE AIRPLANE MUST BE UNDER CONTROL TO DO SO. IF YOUR AIRPLANE IS TAIL HEAVY IT WILL "FLOAT" AND LOSE TENSION COMING INTO THE WIND AND IT DOESN'T MATTER IF YOU'RE PAUL WALKER OR PAUL MCGILLICUDY. IF YOU CAN'T WHIP YOUR SHIP FOR LANDING IN GOOD AIR, YOU WILL BE IN TROUBLE WHEN THE WIND BLOWS. IF THAT DESCRIBES YOUR AIRPLANE, ADD A LITTLE WEIGHT TO THE NOSE (OR, BETTER, REMOVE IT FROM THE TAIL) AND INCREASE LINE SPACING AT THE HANDLE TO REGAIN ANY LOST MANEUVERABILITY
Ted Fancher
Topic: high wind landing (Read 2601 times)
