Howdy Marc-
In your Hangar Talk note you said “I’m looking for ways to reduce approach speed and runway requirements. Has anybody had success with lowering the stall speed of a longez?”
A Long EZ in our hangar has Jim Price’s vortex generators on the canard and wings. The owner agrees with the advertised ten knots lower landing speed and a two knot loss at top end, with cruise basically unaffected. Sounds like the Price/NASA-developed VGs would do what you are looking for.
I do have another suggestion, at the end. Don’t cheat, work your way down : )
The Trailing Edge Fences on my VariEze do provide slower lift off speed and shorter takeoff distance, and more comfortable approaches at about ten mph slower. However, their benefit is rarely experienced since I am more interested in takeoff energy, letting the plane lift off when it is ready, and usually adding a little speed on sporty landings. Both, out of the benefit arena.
I agree on getting up to speed, or more accurately ‘down’ to speed on landing discipline. Cheap thrills, and cheaper and probably more prudent than the kind of structural mods I think you might have in mind, which I would never be foolish enough to consider… more than every year or so : )
I’m up to about a thousand landings on the VariEze. Your topic reminds me of two learning experiences. Lesson One, in a power out approach, an EZ requires about 22 mph as a buffer to trade off in the flare. Two, to your topic of shorter landings, with appropriate application of that pilot stuff, a guy can make a slower approach and use power to subdue the rate of descent.
There is that very fascinating concept about pitch and power – that I will skip and just postulate that on this subject – a very slow landing approach, adding power will not necessarily make the landing rollout distance longer. The purpose of this note should be obvious, to stir the short landing juices from those in the know.
The 22 MPH Buffer
The first concept – In a power off approach, an EZ requires about 22 mph as a buffer to trade off in the flare. This report came from an F-16/EZ driver and could probably be found in the canard archives if someone wanted to bad enough. If I remember right, his conclusion was based on looking at the aftermath of an over gross EZ on takeoff attempting to make it back to the runway without power, with probably full left and full aft stick. The F-16 driver was generous enough to share what he learned after approximating the situation in his EZ.
We know the EZ is stall resistant. However, in the power off, fully deflected turn he reported a very high (unsurvivable) rate of descent. Assuming again that I am remembering correctly, he worked through a number of wings-level power off approaches in his plane. The take-away was the golden 22 mph tradeoff buffer. Over the years I have observed this to hold water.
Arresting Descent Rate With Power
I don’t approach this type of landing lightly. I work into the 22 mph buffer gradually, and mostly complete these approaches by leveling off while still several feet in the air. In the past I occasionally made a few gratifying landings all the way to terra firma, but now feel no further need to take them all the way to touchdown. I can see making daring steep approaches into some exotic, out of the way strip, or maybe a no-nonsense precautionary landing, but these short srtip imaginings always conclude with the potential of an empty throttle and firmly thudded landing.
I do practice the short approaches. Getting ready for Rwy 02 at RR puts me on my best behavior. Back home when the wheelpants are off, I try to make the 1500 foot turn off. The point is minimal ground roll. But even more important than that is arriving back at the hangar with the gear attach hardware still in place.
Since this includes getting slower than the 22 mph buffer, the first step is at altitude to reconfirm the plane’s minimum speed, *per the operating manual and CPs*, looking for the ability to make gentle turns using combinations of aileron and rudder at full aft stick. Per design and with proper CG, with the canard at max pitch, the wings are still several degrees within their comfort zone.
For me, this min speed is approached very gradually with great care. In my plane, at full aft stick and low power the plane holds altitude, with the nose either nodding up and down a little or holding steady at a high nose attitude. Gentle turns can be made but my interest is that the wings can be returned to level, kinda like a guy would be doing during a landing.
You used to hear of folks doing abnormal things at this slow speed to see if the plane would depart, like making large, multiple control inputs with a purposefully out of limit CG and such, and then be surprised when abnormal things did happen. Not part of this discussion.
Knowing the plane’s minimum speed, plus 22 mph, gives the target power off approach speed where you still have the ability to flare and arrest the rate of descent. Since getting slower than this ‘min+22’ number is actually likely a little dicey, a guy can start out his practice at maybe 25 plus and work down. He may never choose to work very far down into the ‘min+ 22’ number. But this provides a target flare speed for an emergency landing. And an appreciation of need for the 22 mph buffer.
What this has meant to me over the years, especially on takeoff, is that upon a power loss I want to get the nose over. In any airplane on climbout, most folks are surprised how quickly speed drops and how much the nose must be pushed over to even hold speed, much less get up to a 22 mph buffer. Regaining speed at low altitude is tough.
The practice short field approaches start out aimed about a third of the way down the runway. At the slower speed, in the “power-flare”, throttle is used to slow and stop the descent rate several feet high. Once leveled off, sometimes a normal touchdown is made.
If taking it all the way down, timing and experience and luck during the throttle application will hopefully make it look like we did all that pilot stuff right.
The fun part to see here, contrary to common sense, is whether adding power in the flare can reduce the ground roll, or if the airplane is propelled further down the runway.
If you do this Marc, check out your starting “ability” to see how much time and money you saved : )
A potentially expensive element in play here is prop clearance. I have encouraged folks on their first front seat flight to put the extended nose wheel on a paint can sit in the plane and imprint that attitude for first-flight rotation attitude and approach attitude sight picture. But for more aggressive landings, a guy needs determine his max desirable attitude with acceptable prop clearance.
All this is said in agreement with Drew and Waiter and others about there being little margin for error at the slow end. And to step back another ten paces- other than practicing the slow landings, I seldom take advantage of the benefits of the TE Fences because more often than not I add ten mph to my approach and touchdown speed. On takeoff I normally let the bird lift off when it is ready and accelerate to 150 mph to climb. Bottom line, energy is our friend.
But Marc your interest is to land slower. Or maybe to install high lift devices. I probably won’t be able to stay away from that thought either…
Hope you get more good info and that your short landing pursuit here gets you what you want.
You mentioned Micro vortex generator’s claim of 9 knots reduction, and if it was real, lots more folks would have them installed. I am wondering how often when someone gets the vgs on their EZ, they have some fun and success, and good capability if and when they need it. And thus satisfied, thereafter are somewhat leery of the very bottom left corner of the flight envelope. As on most airplanes.
If and when you are fortunate enough to get a chance, like i did, let someone who knows how to fly the airplane show you short field landings in a stock 0-235 LongEZ. Maybe you are that guy, to show someone else.
Oh yes… on lowering stall speed? For real?
Some might say the following solution is free, or even saves cost…
Others might say it “costs too much”…
An airplane always stalls at the same angle, with higher weight causing higher stall speed, lower weight allowing a lower stall speed. A sure-fire stall speed improvement… reduce weight : )
Good flying- and landings,
Bill James, Fort Worth VariEze
