steingar Posted September 13, 2018 Report Posted September 13, 2018 3 minutes ago, jaylw314 said: 90 KIAS is a little on the slow side for the approach phase, too close to best glide sped (where the backside of the power curve starts). I'd suggest 95-100 KIAS, that works all the way down to 250 feet--if you cut power and slow down on final from that height, you'll cross the threshold around 80-85 KIAS. Not good for short runways, but you're not going to be coming down to 250 feet without an ILS or LPV We'll see, I haven't started the IR yet and won't for awhile. By the time I get done paying for all the avionics I'm going to be tapped and will have to save upper a bit. At that point we'll see what works. Can't say I'm thrilled at the thought of being on short final at 100mph. Book says my Mooney stalls dirty at 57mph, 100 is way more than 1.3Vso. Coming in at that speed I'll float halfway to Cleveland. 2 Quote
RobertGary1 Posted September 13, 2018 Report Posted September 13, 2018 18 minutes ago, jaylw314 said: 90 KIAS is a little on the slow side for the approach phase, too close to best glide sped (where the backside of the power curve starts). I'd suggest 95-100 KIAS, that works all the way down to 250 feet--if you cut power and slow down on final from that height, you'll cross the threshold around 80-85 KIAS. Not good for short runways, but you're not going to be coming down to 250 feet without an ILS or LPV FAA plates only show timing for 60,90,120+ knots so you should pick one of those or your timer won't be useful. Chopping throttle at 200 feet and dumping flaps will slow you done well. Shooting an approach to 200 feet and then landing on a short field will always be interesting; fortunately its rare, most airports with those types of mins have long runways. -Robert, CFII 2 Quote
rahill Posted September 13, 2018 Report Posted September 13, 2018 40 minutes ago, jaylw314 said: 90 KIAS is a little on the slow side for the approach phase, too close to best glide sped (where the backside of the power curve starts). I'd suggest 95-100 KIAS, that works all the way down to 250 feet--if you cut power and slow down on final from that height, you'll cross the threshold around 80-85 KIAS. Not good for short runways, but you're not going to be coming down to 250 feet without an ILS or LPV Can you double check this, or provide a reference? Best glide in an M20J is about 90 kts (load dependent). The low point in power curve (left of which is "backside") is the point of minimum drag, not the point of best glide. Best glide (L/Dmax) is to the right of that. I know we're mixing up topics now, but if you cross the threshold of Palo Alto at 80-85 KIAS, you're probably not going to land on that attempt. Rich 2 Quote
ArtVandelay Posted September 13, 2018 Report Posted September 13, 2018 FAA plates only show timing for 60,90,120+ knots so you should pick one of those or your timer won't be useful. Chopping throttle at 200 feet and dumping flaps will slow you done well. Shooting an approach to 200 feet and then landing on a short field will always be interesting; fortunately its rare, most airports with those types of mins have long runways. -Robert, CFII Timed approach? Anybody still do those for real anymore? I’d recommend practicing the chop & dump a few times...be sure you are on the glide path and do it in low wind conditions to give you an idea of your expected landing distance...remember you have to trim the plane as you dump the flaps. I extend speed brakes and cowl flaps as well. 1 Quote
ArtVandelay Posted September 13, 2018 Report Posted September 13, 2018 Can you double check this, or provide a reference? Best glide in an M20J is about 90 kts (load dependent). The low point in power curve (left of which is "backside") is the point of minimum drag, not the point of best glide. Best glide (L/Dmax) is to the right of that. I know we're mixing up topics now, but if you cross the threshold of Palo Alto at 80-85 KIAS, you're probably not going to land on that attempt. Rich Also, there is approach speed versus threshold speeds....sometimes the discussion gets muddled. Probably would be good to know how much speed you can lose from 200’, that way you can make the go around decision early. Quote
jaylw314 Posted September 13, 2018 Report Posted September 13, 2018 20 minutes ago, rahill said: Can you double check this, or provide a reference? Best glide in an M20J is about 90 kts (load dependent). The low point in power curve (left of which is "backside") is the point of minimum drag, not the point of best glide. Best glide (L/Dmax) is to the right of that. I know we're mixing up topics now, but if you cross the threshold of Palo Alto at 80-85 KIAS, you're probably not going to land on that attempt. Rich Hmm, I was inaccurate--"backside of the power curve" is below best climb speed (85 KIAS or so). The point is, above that, pitching down increases speed and increases descent (and vice versa for pitch up) like you want on an approach. However, below that, pitching up reduces speed and increases descent, which is a little funky for instrument flying (as well as unstable). PAO does not have an LPV, you'd be coming out of the clouds at least 450 AGL, so much more time to slow done to 70 KIAS. Any place with an ILS or LPV down to 250 feet or lower is going to be a bigger runway. When I do a timed approach, I do the approach at 105 KIAS. Halfway between 90 and 120, so halfway between the times. Not that I've done one since training, though... Here's an approach I made to KSMO right down to minimums (270' AGL). The approach was at 105 KIAS. Unfortunately, I don't have the airspeed over the numbers (that camera fell off the window early in the flight). You can see and hear the power cutting right when coming out. The runway had already been shortened to 3500' by this time. If I counted the stripes correctly, I made the 3200' turn off with basically no braking: Quote
RobertGary1 Posted September 13, 2018 Report Posted September 13, 2018 I'm surprised you used any power. I'm usually power off, full flaps and in a full rudder slip in the clouds to get down. You have lot 2 miles to lose 1500 feet after WURUD on the VOR approach. -Robert Quote
Piloto Posted September 13, 2018 Report Posted September 13, 2018 (edited) Most important when approaching a short runway is that you have a headwind and not a tail wind, specially when landing at isolated fields. On final I always verify that my ground speed is less than 65 kts or less than the airspeed. A sudden wind direction can happens anytime there is weather above. José Edited September 13, 2018 by Piloto 2 Quote
jaylw314 Posted September 13, 2018 Report Posted September 13, 2018 1 hour ago, RobertGary1 said: I'm surprised you used any power. I'm usually power off, full flaps and in a full rudder slip in the clouds to get down. You have lot 2 miles to lose 1500 feet after WURUD on the VOR approach. -Robert Ooops, I should have clarified that was the LPV minimum on the RNAV 21 approach. I imagine the VOR-A approach you need to drop like a rock! Come to think of it, on the RNAV 21, I was annoyed thinking ATC slam-dunked me by giving me 6000' and vectoring me to two miles outside the nominal FAF, which means 2 nm to lose 3000'. THAT pretty much takes an emergency descent! When I looked it up though, it seems that coming from the north, the MIA is, in fact, 6000', so it wasn't just a case of getting hosed by ATC... Quote
Herlihy Brother Posted September 16, 2018 Report Posted September 16, 2018 On 9/13/2018 at 5:52 AM, MyNameIsNobody said: You left out flaps. You have full flaps too, right? Well yes, I left out flaps and gear, but included "Dirty" by which I meant "dirty configuration" or the "landing configuration" which I thought was an aviation term. I never know because all the wwII pilots that taught me are long gone and maybe they made that term up. Their "dangerous" techniques like whip stalls and slips with full flaps and short approaches dragging in under full power are not taught anymore either it seems. Those old timers launched me into 200 overcast saying it clears up a few miles inland. At PAO where I tested, the rule for students was 3000' minimum ceiling. Quote
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