Mike Taglieri wrote: >>All this talk about landing speeds makes me wonder whether everyone is using >>true airspeeds. At landing, IAS can be off by quite a bit because the pitot >>isn't parallel to the airstream. If you don't have a GPS, it would be >>worthwhile to try some landings (on a windless day) with a car GPS in the >>plane to see if the speed check out.<<
And "Tony" wrote: >> How would that help? When landing an aircraft, surely the appropriate >> reference for airspeed (apart from the feel of the aircraft in flight) is >> the instruments fitted in the aircraft? IAS is what you'll have in front of >> you when landing. << I'm pretty sure the "real" pilots on the list use GPS speed when reporting something like landing speed. I certainly do, and am pretty sure others do as well. IAS is quite valid when you or someone else is flying your plane, but any time you are trying to convey an ACTUAL touchdown speed, GPS speed is way more helpful than the speed somebody else gets on their airspeed indicator on who knows what kind of day. When I talk about landing speeds, it's something that's universal across the planet...GPS speed. Granted there are small variations on what your landing speed will be depending on altitude of the runway, temperatures, wind (although it should be calm) and air density (probably phase of the moon...to some extent), at least GPS speed is a whole lot closer to consistent (given than the vagaries of the poorly calibrated Indicated Air Speed. I think most of us know that, so GPS or True Air Speed (which should be pretty dang close to each other) would normally be associated with a speed used for landing when talking between pilots of different airplanes. Having said that, I'll repeat again that my GPS speeds when landing N56ML were right at 60 mph at touchdown. This is "definitely done flying" in landing configuration, full flaps. About half the time the tailwheel hits first, the other half the mains hit first. Either way, it's not going to bounce back off the ground and start flying again...it'd done. N891JF is pretty much the same way, which is not surprising. It doesn't have the extra lift from the flaps, but has a little lower wing loading. Speaking of N891JF, Jim has mentioned "seeing speeds as low as 40 mph" while landing (in his "The Perfect Landing" piece at http://jfaughn.com/other/kr/uniquepartsofmykr/kr_landing.html ), so he's definitely talking about IAS, rather than GPS. I can assure you that plane will not be flying at 40 mph airspeed! He's excused, because they didn't even have GPS back when he wrote that, and doing any kind of stopwatch trial over a known distance is iffy, and downright dangerous as absolute minimum speed. For this reason, be careful when reading old newsletters touting speeds, and certainly view promotional KR stuff written in the 70's with that in mind. While I'm on my high horse, it's worth mentioning that True Airspeed (TAS ) is the universal language for comparing performance in general. In N56ML I used to spend a lot of time (and mental gymnastics) doing that in my head while flying, but the iEFIS in N891JF has a continuous display of TAS (as well as ground speed and indicated airspeed), so two guys flying in formation (or trying to rendezvous) should be reading exactly the same TAS while side by side, assuming they're TAS has been correctly calibrated through flight testing. I've spent a lot of time calibrating mine, and I make a point of doing that kind of thing on 29.92" / 59 degree days to ensure accuracy, so I have a lot of faith in my numbers. Beginning pilots may wonder why they appear to by flying slower as they gain altitude. Your plane is probably no slower, maybe even faster. It's all about true airspeed vs indicated airspeed. There's a huge difference at higher altitudes.... Mark Langford, Harvest, AL ML at N56ML.com www.N56ML.com
