On December 13th, 1994, Tom Hamilton (idea man extraordinaire, designer, and head of the design team for the GlaStar) handed me the keys to the (then two week old) prototype GlaStar and asked me if I’d like to fly it. I beat him out the door and the early video, which many of you have seen, shows me getting into the airplane to go flying.
It was a blast to fly but needed a lot of work to turn into the spectacular GlaStar of today. The flaps were not working yet, and so I was told to “keep the speed up, don’t stall it and DON’T CRASH IT.” I quickly found out what a great glider the GlaStar is because I couldn’t make it come down when I pulled power to idle, opposite the numbers. At 90 knots in this light GlaStar, I only lost 300’ or so and couldn’t make the 5,000’ runway.
Granted, by the second go-around, I was laughing at myself and realized I would have to slow this airplane down somehow or start landing from a lower pattern altitude. I relearned two important lessons that day. One, adapt to the airplane you are flying, i.e., don’t assume it will be like another plane you’re more familiar with (I had just been flying a Glasair III which uses 120 knots in the pattern and 100 knots for final approach speed) and second, good approaches really do set you up for good landings.
Today, the technique we use on landings in demo flights is to apply flaps, fly airspeed at 65 to 70 knots at idle power and always add or remove power for descent control if below 65 knots (76 mph). Sure, I know 65 knots is a little on the fast side but hundreds of demo flights later, many of you have marveled at the gentle landings you made in the GlaStar without power, even on your first demo flight. So how come the GlaStar has bent a few egos on hard landings and even bent a few landing gear legs (and more) on harder landings?
First, some background: The GlaStar airfoil was chosen, among other things, for its combination of high cruise speed and gentle stall characteristics.
With the addition of slotted, rearward moving flaps the stall speed lowers and both lift and drag increase for better slow flight control. (Remember my trouble descending in that first flight, no-flap landing?) All aircraft have a critical airspeed, which you don’t want to go below without the addition of power to control the coming sink. With the GlaStar it is a sink you can learn to feel and control with power.
Second, the good news is the landing gear legs were designed to bend (and be repairable) not break, without hurting the cage. To check a leg, place a straight edge along side an unloaded gear leg. It should reveal a perfectly straight, tapered, torsion bar on any side.
I observed a real rough landing where the G meter read + 4.2 Gs and the left gear leg (which hit first) bent in a gentle bow (about 1”) throughout the length of the leg. If you wonder whether your gear is straight, inflate tires equally and measure the height of the wingtips on a flat floor when your GlaStar is new or before any hard landings. Built correctly, with equal tire wear and pressure, both wing tips should measure the same
height. Log any difference for future comparison. Although this is rather imprecise, a quick measure of any height difference later on (with equal tires, etc.) will reveal a change in the straightness of the gear leg. A more complete check is to remove the gear leg pant, lift the airplane by its lifting eyes until the tire has almost no weight on it and use the straight edge method along side the leg to check for any permanent bend that should not be present.
If the leg were bent then I’d check the cage socket area for signs of cracking, distortion or movement. It is possible (but may not be prudent) to fly the GlaStar with a slightly bent leg as long as the cage is OK and the wheel tracks straight enough for a safe takeoff and landing. The good news is the leg can be removed from the cage, brake assembly removed and sent to a qualified steel heat-treater or Langair Machining, maker of the gear leg, for straitening. The material of the legs is 6150 steel, and they are heat-treated to a 42-44 on the Rockwell Hardness Scale. If only bent a degree or two then a “warm up” to 800 degrees and straightening can proceed. (Warming up higher than 850 degrees affects the steel hardness.) Repaint and reinstall. If bent more, then it must be annealed (to make it soft), straightened in a press (like car springs are re-arced) and then heat-treated (in the vertical position) back to the design specs. Painted and reinstalled it will work like new. In fact the prototype flew its last 700 hours or so (with lots of demo landings) on a left main gear leg repaired in the above manner. It still sits on that straightened gear leg in the museum at Oshkosh.
So, after observing lots of landings in various configurations we choose 65 knots (76 mph) as a simple, safe speed for short final. If you stay at or slightly above that speed until 2 or 3 feet off the runway and then let the speed slow a bit as you flare to a smooth landing on the main gear, (or continue the flare to a three point stall in the tail-dragger), the sink (with flaps applied but without power) should not be an issue. Add a few knots if the winds get squirrelly and by all means go-around if in a microburst area. If you get below 65 knots (76 mph) indicated, then start adding power (and be ready to quickly add lots of power) because that infamous sink will want to start occurring the slower you go. Would you let me know if you’ve hit the ground too hard when following the above technique in a GlaStar?