Assuming a simple aircraft with no flaps, if you want to fly your approach at a given speed and a given rate of descent then the pitch angle only has one possible value, yes?
(Disregarding going onto the back of the drag curve and hanging it on the prop at high pitch & high power.)
The question has come about due to a discussion about how one positions a taildragger for a wheeler landing vs a three-pointer.
What about the power setting though? Attitude plus power equals performance
Not sure if the type of “approach technique” (pitch for speed vs point and gun with power) is relevant to “flare technique” (wheeler vs tri-point)
Definitely flaring and doing wheeler without power is tough while 3 points without power is damn easy…
Graham wrote:
if you want to fly your approach at a given speed and a given rate of descent then the pitch angle only has one possible value, yes?
For a given approach, yes. For different flights, no – you have to factor in the weight.
For a given approach, in equilibrium, AoA and speed are in a fixed relationship.
With a tail wheel plane, it is also possible to pitch to a lower AoA at a given airspeed just above the ground, and hit the ground with the main wheels first before falling very far, and therefore before reestablishing equilibrium at a higher airspeed. Then once the main wheels are on the ground and supporting weight, you are in a different situation. It takes skill to do this without pitching up to higher AoA at ‘impact’ and creating a mess.
A highly skilled friend habitually likes to fly it on (in equilibrium) to a transport landing (meaning a tail low wheel landing), then once rolling on the mains use down elevator to lower AoA, unloading the wing and putting weight on the main wheels. This gives you almost the same low touchdown speed as you get with a three point attitude landing, combined with the potential to brake associated with a wheel landing at low AoA. He then lowers the tail fairly rapidly to the ground as speed and rudder authority drops, shortening the period in which neither rudder nor tail wheel is in full authority and directional control is weak.
MattL wrote:
What about the power setting though?
There is only one power setting at which the given pair of airspeed/rate of descent is achievable.
I thought this was the case.
The context was me suggesting that to arrive in the hold-off in a level attitude for a wheel landing, one would necessarily have to be going a little faster than when holding off in the three-point attitude, otherwise the rate of descent would be greater. @Silvaire has explained how this is achieved in practice – only going to the level attitude at the last moment and even then not all the way until after the wheels are down.
The person I was discussing it with said that the greater rate of descent was countered by adding power. I responded that this would increase the speed, and he said no because power controls rate of descent and pitch controls speed. Of course I said that power also controls speed unless you change the pitch to maintain the speed. I wonder if he has not fully appreciated what the trimmer does?
the greater rate of descent was countered by adding power. I responded that this would increase the speed
If the right about of power is add to break RoD then speed will not increase…
For wheeler without power, you have to start flaring on speeds higher than best glide or min drag, pitching up tend to reduce your overall drag & gradient, if you flare on slower speeds, it increase your RoD on touchdown unless you 3 point it…
Ibra wrote:
If the right about of power is add to break RoD then speed will not increase…
I know we often add a little burst of power to arrest the rate of descent, but in doing so the speed must necessarily increase (or just not decrease as quickly – the speed is often decaying at this stage) unless we pitch up (it may be so slight and subtle that we hardly notice) to maintain the speed. The point I was making to the chap I was discussing it with was that this pitch up, in setting oneself up for a wheel landing, was not desirable.
The simplest proof of this surely is to fly along hands-off, trimmed at a given speed, and adjust the throttle. With every movement of the throttle, the pitch changes to maintain the speed. Conversely if you play with the throttle whilst using the AI to resolutely maintain a level attitude, the ASI is what will respond to every movement of the throttle.
I used to read a lot of articles by John Farley who AIUI was a test pilot on aircraft such as the Harrier and many more.
He advised controlling speed using the throttle in descent.
Standard teaching is to control speed with pitch and descent rate with attitude.
I have tried both methods and they both seem to work so IMO you.do what you feel works best for you.
However the flare is another matter. Arrive to fast and you will balloon. Flare too much and the tail wheel touches first with often catastrophic results.
A 3 pointer needs you to balance touch down and forward momentum with low speed.
A main wheel first landing means having enough speed to fly straight and level yet gradually sink before being slow enough to pull the stick right back.
Too fast and you will either bounce or find it very difficult to stop without going tail over head.
Each aircraft is different. In a Stampe for instance for a 3 pointer you usually end up adding an quick burst of throttle just after the flare and pulling the stick back at the same time.
To land on main wheels you tend to add a little throttle in the flare, keep it, then slowly reduce.
On the other hand you might be doing a power off landing which means holding the speed and flying totally by attitude.
