Bob - S50 Posted August 24, 2016 Report Posted August 24, 2016 Just a technicality, but at altitudes near sea level or in the landing pattern, I don't think we ever get 'behind the power curve' in our Mooneys. We get on the left side of the drag curve, but not behind the power curve. That is, we do frequently get to a point where a reduction in speed requires an increase in power to maintain speed and altitude, but we never get to a point (in level flight) where we do not have enough power to maintain altitude and airspeed. I haven't tried it, but I suspect that even at stall speed, we have enough excess power remaining to accelerate while maintaining altitude. However, climb to a high enough altitude where the engine cannot make much power and it might be possible to get behind the power curve. To me, being behind the power curve results in the famous 'Saber dance' of the F100 that tried to go around too late. Quote
Shadrach Posted August 24, 2016 Report Posted August 24, 2016 23 hours ago, gsengle said: But it *is* amazing how steeply you can approach with power on, on the back side of the power curve, if you need to. But in that regime any power loss requires lowering the nose immediately. Sent from my iPhone using Tapatalk IMHO, far steeper approaches can be achieved power off. However, one must be willing to really slow (1.2*Vso or less) the aircraft down in near level flight before descending. In a light plane like my F model, letting the speed come back power off to say 75MIAS (maybe even 70MIAS) and then maintaining that speed with pitch will yield a very steep descent with great visibility over the nose. A blast of power will immediately arrest the descent. I am not a fan of "dragging" in laminar flow wings behind the power curve. Quote
gsengle Posted August 24, 2016 Report Posted August 24, 2016 Back side of the power curve = left side.... Sent from my iPhone using Tapatalk Quote
donkaye Posted August 24, 2016 Author Report Posted August 24, 2016 33 minutes ago, Bob - S50 said: Or, add power to accelerate and simultaneously lower the nose to keep from climbing. Potato, Pattaato. Not really. Add power and the nose will rise, slowing the plane further. IMHO the thought process for safety should be to lower the nose while adding power. Look, Bob, no problem with what you are saying. Because of the simultaneity, it will work. But I want my students to recognize the forces at work here. So I want them unconsciously to think nose down first as they add power simultaneously. Look, the discussion is good. It is good to have your experience on board. 1 Quote
gsengle Posted August 24, 2016 Report Posted August 24, 2016 23 hours ago, gsengle said: But it *is* amazing how steeply you can approach with power on, on the back side of the power curve, if you need to. But in that regime any power loss requires lowering the nose immediately. Sent from my iPhone using Tapatalk IMHO, far steeper approaches can be achieved power off. However, one must be willing to really slow (1.2*Vso or less) the aircraft down in near level flight before descending. In a light plane like my F model, letting the speed come back power off to say 75MIAS (maybe even 70MIAS) and then maintaining that speed with pitch will yield a very steep descent with great visibility over the nose. A blast of power will immediately arrest the descent. I am not a fan of "dragging" in laminar flow wings behind the power curve. Yes of course, steepest is slow with no power sinking back side of the power curve. At those same speeds any shallower approach requires power, for that short field landing. And that super steep one requires power or a last minute nose over with good timing to be able to flare and not slam into runway... Sent from my iPhone using Tapatalk 1 Quote
Shadrach Posted August 24, 2016 Report Posted August 24, 2016 17 minutes ago, gsengle said: Back side of the power curve = left side.... Sent from my iPhone using Tapatalk Exactly, left of minimum power required for level flight is the area of reverse command, Steep power on approaches occur in this area. It's not a place where I like to spend time. Quote
markejackson02 Posted August 24, 2016 Report Posted August 24, 2016 At the risk of starting the flames all over, why is it that we aren't taught about energy? If a CFI asks me to hold 110 kts at 5000', he is asking me to maintain a certain energy state. Altitude is just a form of potential energy, etc. Would seem to be a lot more straight-forward. Isn't that what they teach fighter pilots? 2 Quote
Shadrach Posted August 24, 2016 Report Posted August 24, 2016 2 hours ago, gsengle said: Yes of course, steepest is slow with no power sinking back side of the power curve. At those same speeds any shallower approach requires power, for that short field landing. And that super steep one requires power or a last minute nose over with good timing to be able to flare and not slam into runway... Sent from my iPhone using Tapatalk 1) If an airframe is producing no thrust (or negative with the prop windmilling) how can it be on the back side of the power curve? Certainly it's left of L/Dmax, but that is not the same thing. 2) Compared to steep power off descents, steep power on descents produce slightly less parasitic drag at the expense of significantly more induced drag and thereby more total drag. 3) Back of the power curve flying in a laminar flow wing aircraft is the regime that presents the greatest risk of stall spin. 4) I've done a lot of short field work in a mid body into paved and turf strips. It does not "slam" into the runway. There is no need for a last minute nose over or blast of power (long body may be different) in a mid body. It may "feel" like it's needed, but it's not. In ground effect Vso is reduce effectively (pun intended) giving adequate margin for a deep, high AOA flare and soft touchdown. The key is fighting the urge to round out too soon and too high. One needs to maintain a stable power off speed all the way to the TDZ, followed by a swift flare, culminating with a smooth. full stall, full aft elevator touch down...and a very short roll out. Quote
gsengle Posted August 24, 2016 Report Posted August 24, 2016 The back side of the power curve is the same thing as left of L/D max. Just like a stall has nothing to do with an engine... Sent from my iPhone using Tapatalk Quote
Shadrach Posted August 24, 2016 Report Posted August 24, 2016 Just now, gsengle said: The back side of the power curve is the same thing as left of L/D max. Just like a stall has nothing to do with an engine... Sent from my iPhone using Tapatalk Negative... Quote
gsengle Posted August 24, 2016 Report Posted August 24, 2016 Yes and no. Power *or* descent required. That's level flight. Power curve is the simple name for that chart... Works for gliding too. https://en.m.wikipedia.org/wiki/Gliding_flight Sent from my iPhone using Tapatalk Quote
Shadrach Posted August 24, 2016 Report Posted August 24, 2016 It could be level flight, but it's not necessarily depicting level flight. This graph is a hypothetical the minimum power point could just as easily be depicting a descent as level flight. After all "some" power does not equal enough power to maintain level flight The difference between a steep power off descent and and a steep power on descent is the effect additional power will have on the aircraft. In a steep power on descent (behind the power curve) adding power and raising the nose will result in a decrease in airspeed and an increase in descent rate. In a steep power off descent adding power and raising the nose will result in an increase in airspeed and a decrease in descent rate. Quote
gsengle Posted August 24, 2016 Report Posted August 24, 2016 Ok call it the L/D curve if it makes you happier, still all applies... Sent from my iPhone using Tapatalk Quote
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