Best Rate of Climb | Vx vs Vy | Region of Reverse Command | Power Curve
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- Опубликовано: 18 июн 2024
- On a normal takeoff, we typically pitch for the speed that gives us our best rate of climb, known as Vy. What causes our best rate to be found at this speed, and what is the difference between Vx vs Vy? Something called the region of reverse command plays a big role in these differences.
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Great Explaination. Thanks
I’m considering recommending these videos to students when I get my CFI cert. Thanks for the great explanations and graphics!
Thanks! Hope it can be helpful to your students
I just bought the G1000 course and I think it's great for get overall view of GA…However some terminology seems need to be understood beforehand which bring difficulties,hence I even need other aircrafts' manuals (honeywell's and so on ) to get familiar with it.
So if a book can be written, or to recommend other books to assist the course will be helpful.
PS:The GA in China is still in infancy but developing, for now I only can get what available around me,even maintance manual for avionic Epic Primus …sounds strange but still trying to find way though,hnm
I had floats added to my plane . How how do I find Vx and Vy with weight and drag?
Hi dan, I was wondering if this material is already available on the site since it's a complex one for me. thanks
It’s not part of any course we currently offer, but will be soon!
I dont know the difference between power and thrust though. Or is it like that; they are the same for jet engines and somehow different for piston engines? If so why? Also, why were the power available and thrust available curves were drawn like that? Not implying they are wrong just wanna know why. Would their shapes change if it was a constant speed propelled aircraft? What are the factors for decreasing amount of available power and thrust other than altitude temperature and air pressure? Thanks...
Power is required to turn a propeller. Thrust is the result of turning a propeller, but as it is variable with speed, less so with a constant speed propeller, the curves are not the same. Piston engines are rated for the power they can produce to move the propeller.
Jet engines are a different thing altogether, power is not used at all with them, just thrust as that is what they produce. In effect they produce zero power when having full take off thrust while still standing on the brakes. Jet engines are rated for the thrust they produce, which is then used to directly move the aircraft.
Turbo-Prop engines are, again, rated in power, not in thrust.
Thrust is force and power is rate of doing work. Thrust is the force you apply to overcome drag and/or accelerate whilst power is the rate you burn energy whilst doing so. Both these things apply equally to props and turbines.
Keep in mind that both props and turbines work by accelerating the incoming air flow. Each system is limited in its own way. To oversimplify somewhat, a turbine is limited by Mach 1 in the jet nozzle (which is greater than Mach 1 flight speed due to the extreme heat) and a prop is limited by a tip speed of Mach 1 (that is not to say that prop wash is near Mach 1, just that the tip speed limits the thrust). In both cases, as incoming airspeed increases it can be accelerated less before reaching the upper limit, hence, thrust inevitably reduces with airspeed.
A distinction arises in the characteristic curves of the two propulsion systems because the airflow through the turbine benefits from increasing ram effect with speed. The ram effect offsets the underlying loss of thrust at high speed. Thrust becomes nearly constant wrt TAS. But piston engine airflow (and here I am referring to through the engine not prop) is mainly dependant on RPM and virtually independent of airspeed so loss of propeller efficiency is not offset.
This characteristic difference gives rise to the concept that turbines are ‘thrust producers’ whilst pistons are ‘power producers’. That should not be taken literally, but the differences impact on performance so they are worth understanding.
hey, did you ever get your head around why Vx relates to excess thrust and Vy relates to excess power? All the explanations I've read (such as the replies here) only explain that thrust and power are different, and that the curves are different - they don't explain WHY you use thrust in one scenario and power in the other, rather they merely assert that this is what you have to do. I get stuck in this loop with ChatGPT too :)
This fried my brain I’m lost
Was that MSFS 2020?
I am curious also. Looks good
Yep
So, the airspeed is the most important factor?
Best angle of climb speed, VX 59 kt for a cessna 172, right?
You wrote "pitch for the speed" in the description.
Does that mean, full throttle, but literally pulling the yoke back (which reduces speed) until the plane is flying 59kt at whichever climb rate might be indicated?
Or is the throttle set to the value that gives that speed and one then uses like, a 'best feet per minute' figure on the indicator?
Know what I'm getting at?
Again, like, is it full throttle? And you pull back the yoke until 59 knots, even if that means going upwards like a rocket on the VSI?
Or, is it a rate of climb like "750 f/m" on the VSI? and you use the throttle to set the speed to 59 knots to achieve that climb rate on the VSI with that speed?
Okay, I actually grabbed a cessna POH and the conditions described for takeoffs and best climb are "throttle fully open".
Which I will take as , well, just that. Throttle fully open, plane pitched upwards until speeds match.
Explanation looks not obvious at charts' point of view. Seems like it was taken from nowhere.
He explained it more in his Vx video.