| Author | Message | ||
     Phil & Margie Hodge (N410mp) |
I'm starting to define a research project, to see what I can learn about occasional slow speed problems of both cruciform and conventional tailed Expresses. Independent of pending insurance problems, we have to do something about the number of Expresses that are landing too hard. Based on conversations with some of you that have done that, I think something may be happening beyond bad pilotting that we just don't understand. If they stall at 55, why do they develop a sudden sink/stall at 60 or 70, sometimes? So I plan to install a couple of cameras, a skein or two of yarn, and maybe a few other goodies and see what I can learn. All results will, of course, be shared here. A request, to as many of you as this applies to. Several of you have pulled a similar stunt to mine. Some have fessed up, some haven't, each for our own reasons. I have no interest in who, but I have a very real interest in some data. PLEASE email me with as close to actual weight and cg at the time of your incident. Do it anonymously if you want, that's OK. Signup for a free email address at Hotmail.com, email me your numbers, and then cancel the account, so there will be no way for anyone to trace you if you want. But PLEASE, for all of us, send me your best data. Thanks, Phil phil@joistdesign.com | ||
| jharlow |
I have not experienced the hard landing issue but I can say that the sink rate below 70 kts starts to get much steeper. My normal approach is at 70kts and slow to 65-60 over the threshold and set her down. I have a AOA Sport installed and it has never given a PUSH signal or yellow light on landing at these nembers. I have the convential tail Express and would be happy to fly some tests for your research. Set up a standard program and I bet lots of us will be happy to supply data. John | ||
| Anonymous |
Phil, I have talked with other pilots of high performance/high wing loading airplanes and they all say the vertical sink rate can be quite high when you slow them down, especially without power. Cessna 210's, 310's, F-15's, F-16's etc. A Cessna 172 will float, but not so in a high wing loaded airplane. Jim Butler | ||
| Bill Copeland |
Jim: The discussion in our group out here seems to come to the conclusion that the EXPRESS should be landed carrying some power to touchdown. We think there is ample evidence to support the theory that the power off sink rate is the culprit. The theory is further supported by the experiences of the pilots of our EXPRESS. The difference in touchdown speed is small, but checking the sink rate using some power makes for controlled, comfortable landings. Perhaps the analogy of "stall" landing a 747 will provide an extreme expample of the principle. | ||
| Anonymous |
Bill, I have experienced some "firm" landings when allowing the airplane to get slow, with low power settings as well. I then raised my approach speed to compensate. Then, on a hot, humid, high density altitude day, while loaded pretty heavy, I again taught myself the same lesson. So, I again raised my approach speed to account for density altitude and heavy gross weights. Now, on a hot day, when loaded heavy, I trim the airplane for 100 knots on final, and set the power to maintain the VASI or glideslope. I leave that power setting all the way to the runway. Instead of actually flaring, I just fly parallel to the runway and let the speed bleed off. As soon as the mains touch, I cut the power and hold the nosewheel off as long as I can. This makes for some very nice landings. In some cases I have found myself high on short final, and needing a steeper descent. I then reduce power to achieve the descent, but when I level off prior to touchdown, I bring a little power back in to cushion the touch down. It seems to work out quite well. I hope these aren't "famous last words" and I haven't just jinxed myself to the point I'll break off my landing gear on the next flight. By the way, great to hear from you. How's that airplane flying? Jim | ||
| Chris M |
Hi all, One of the things you might want to try is not deploying the flaps past the 30 degree point. I've noticed that the sink rate goes up considerably when using more flap on a normal approach, probably resulting from airflow separation over the wing/flap (I've heard it's common with a short-chord plain flap arrangement like the Express has). FWIW... I used to fly approaches at 80-85 kts with a bit of power, 30 degrees of flap, 75 kts over the fence, cut the power over the threshold and transition into the flare slowly (letting the airspeed bleed off and gently touch down). With real high loading or density altitudes I may keep a bit more speed and some power through the process. In either case, using full 40 degrees of flaps really livened things up during the approach & flare... 30 degrees seemed to work great (at least for me). Hope this helps in some way... - Chris Michalak | ||
| CHARLEY SCOTT (Hogfan) |
I would offer two thoughts on landing a high performance / high wing loading aircraft. My basic instructor who had just recently been instructing in P-51 fighters allways told me to control air speed with AOA and control sink rate with power. I have used this on many high performance airplanes, ie Bonanza, C-210 and my Glasair. I also agree that it is possible to get into trouble using too much flaps on a short cord wing such as found on most high performance airplanes. | ||
| Wayne Norris |
I can't wait to start flying my plane. There seems to be a disparity between the crusiform tail and the conventional one. Not enough tail volume on the old style. I would recommend that you go up and do some full flap stalls to get an accurate Vs. Does the plane stall before you reach full aft stick? If not then there is not enough tail or to nose heavy. Then multi ply that by 1.3 to use as Vref. Pitch for ref and power to hold VS at 1/2 your Grd spd x 10. ie 120grd spd= -600 on the VSI, standard for an ILS. Pull the power back over the #, pitch up 2-3 degrees and it should slide on, if not than this plane is messed up. Also cross check your ASI on final with GPS, you maybe slower than you think. |