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V-any

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V-any last won the day on August 4 2018

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About V-any

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  1. Lol, was just an easy example. I'm always interesting in learning, so I'm going to explain this the way I understand it in hopes that you either concur, or can explain why I'm wrong. However, I can say without hesitation that if this was as simple as the power required chart being the total drag chart multiplied by speed, then the power required would trend towards zero at zero airspeed, which it obviously doesn't. In the case of helicopters, we're turning a shaft, not thrusting the aircraft (within linear thrust like a jet engine). In a helicopter, the engine power isn't thrust multiplied by speed, it's torque multiplied by RPM. We can assume that RPM (N2) is constant, so that makes torque linearly proportional to horsepower. This means that regardless of flight condition, at any given torque, the engine is producing the same amount of horsepower (work) and burning the same amount of gas. The engine is producing the same amount of power hovering at 80%Tq as it is flying 100kts and pulling 80%Tq. So, power available is torque available (multiplied by some constant). Thus, the point at which you require the least amount of power should be the point at which you have the lowest amount of total drag. As long as fuel burn is linear with torque, maximum endurance speed will be the lowest torque setting, which should be the lowest point on the total drag chart. --- As an aside, there are a few things that I think often obfuscate this topic: One is that you could be talking about the power produced by the engine specifically (which is more natural from a pilot perspective, because we have engine gauges) OR you could be talking about the power produced by the entire power train and aerodynamic surfaces. The second factor is that the engine is a turboshaft. This is different than a turbojet or rocket engine, where thrust available is linear and relatively constant and power increases as speed increases (due to multiplying by speed). The third is that the rotor system directly produces both lift and thrust, not primarily thrust like in an airplane. So, at a hover, the system in it's entirety isn't producing any work (because the helicopter isn't moving). However, it is producing an upward force equivalent to its weight, and the engine is producing power in the form of turning the drive shaft.
  2. So how much power is required when you're in a hover (speed is zero)?
  3. I look forward to being told that I'm wrong, and how, but to me that chart doesn't make sense. An aircraft in a steady state is in balance. It's losing energy continuously due to drag. The aircraft has to make power to replace that energy to keep it in a steady state. Therefore, minimum total drag should be the point where the least power is required. So, by my understanding, max endurance should be somewhere near minimum total drag, aka least power required. The only caveat I can think of is that power produced at the rotor blades might not necessary scale linearly with fuel flow, and ultimately, it's fuel flow that we're concerned with; it's a factor in both performance measures. Max range is knots/fuel-flow. Max endurance is simply the speed where fuel-flow is the least. If you want to find max endurance, go to to your cruise charts and find the cruise configuration where your fuel flow is the least.
  4. Updated top post, available again.
  5. You're right about the R44. If you own it for a full 12 year cycle, you need to fly it a couple hundred hours per year to keep the hourly cost from skyrocketing. However, you may be able to find one that has a lot of calendar time left but not a lot of hours. A ship with five years left on it and only 500 hundred hours left might be had a nice discount. And, don't forget, if get a good deal on the overhaul, there's money to be made by overhauling it and selling it with fresh components.
  6. There's absolutely nothing wrong with pay to ferry. They have an empty seat. That seat has value. The business dealings outside of that transaction are entirely irrelevant. Anyone who thinks otherwise either (1) doesn't understand economics, or (2) believes that for-profit helicopter operators should give away services of value for free. However, that isn't a competitive price. For $5/hr more, $380/hr, you can go get dual instruction in an R44 and work on whatever you need to work on instead of fly in a straight-line. Nothing wrong with the concept, but the price isn't particularly good.
  7. Trim and balance (ball in the center) are two different things.
  8. Neither the inclinometer nor the Aspen will tell you if the helicopter is in trim. Only the string will. The string points straight back when it's in trim. This was answered in the first reply. Everyone pay attention: ... It's just a string. Not a magical string that knows where the pilot sits and points to him when it's in trim, it's just a damn string. When air hits it from the front, it points aft. When air hits it from the side, it points to the opposite side. ... sometimes helicopter pilots amaze me.
  9. It's just a piece of yarn. When when the wind is directly from the front, it pushes the yarn directly aft, and it's in trim.
  10. Or they can afford to self-insure up to $80k. Many robust companies self-insure.
  11. That's a little lower than I would expect it to be. Keep in mind that training beats up aircraft. Even if they fix the big stuff that htey break, there's a lot of wear in tear in the training environment.
  12. JohnnyB's post is spot on. A small school, or even a freelance instructor, can be great, or terrible. The lack of a formal organizational structure isn't necessarily a bad thing. However, there's probably greater variance in the quality of instruction you find at schools that meet that description. (Worse bad experiences, better good experiences.) The bigger, more formal schools are more consistently mediocre, in my opinion. That's not necessarily a bad thing. There's certainly advantages to a known quantity. So, it's really situation dependent. A great instructor can thrive in the environment you describe. A poor instructor in the same environment can cost you a lot of money, time, and get away with being less safe. On a separate note, are you training in/near North Carolina?
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