Jump to content

Eric Hunt

VR Member
  • Content Count

  • Joined

  • Last visited

  • Days Won


Eric Hunt last won the day on August 25

Eric Hunt had the most liked content!

Community Reputation

413 Excellent

About Eric Hunt

  • Rank
    VR Veteran Poster

Profile Information

  • Gender
  • Location
    Near the beach

Recent Profile Visitors

885 profile views
  1. Remember that the "speed" can be the physical speed of the aircraft through the air (parasite and profile drag increasing) or it can be the Relative Air Flow (RAF) to the blades in the hover or in forward flight. (Induced Flow). In the hover, the downward induced flow is highest, and the Total Reaction is tilted further back from the RAF. It is producing plenty of lift, but a larger component of it is pointed backwards (drag) and the drag component points downwards (weight), so the poor old rotor is producing Lift+Thrust to overcome it. The speed squared is the RAF, in this case, and is certainly not zero when in the hover. In forward flight, there is less IF, so the TR moves forward, more is available for Lift and less is used up in Drag, so the curve moves downward while the others move upward. The work being done is pushing the airflow downwards. No work, no fly. The engine is the ONLY thing producing power, the rest of them are chewing it up. The power can be converted to Kinetic Energy (speed) or Potential Energy (altitude) and these are the things that you can use up to produce the autorotative forces that allow you to control descent when the engine goes on holidays. But you only get one bite at KE+PE, once you use it, it's gone.
  2. The power curve is made up of 3 components, one of which is the power to overcome induced drag, which is greatest at zero airspeed. It then works its way down. Of the other 2 components, one starts at either zero and the other is at a mid-level, and work their way up. The induced flow is moving, it still takes power to suck the air from the top and push it out the bottom. And power to overcome transmission drag, hydraulic pumps, generators and such. But I know you were just having a poke for fun. Too easy.
  3. V-any, are you looking for the definition of Power? Or are you asking why there are 2 charts, one showing drag and the next showing power? The power chart is a slightly different shape from the drag chart, because speed has to be factored in. You won't overcome any drag without using power. Work = Force x distance, the force in this case is Drag, proportional to Speed squared (CL x 1/2 rho x speed squared) Power = work / time So, Power = drag(speed squared) x distance / time, and distance / time = speed, which makes the equation: Power = speed cubed times the Bernouilli bits. Simples.
  4. This chart is from your FAA -H-8083-21B handbook. Note that it talks about Power, not Drag. Yes I can see why you are hung up on drag, but it is the Power Required to Overcome Drag that is why you stay in the air - or not. Multiply drag times speed to get the basis of power. And as usual, this book is full of errors. It labels the right side of the rising curve as "power required to hover OGE", but the corresponding speeds range from 65kt to 100kt. That caption should be at the far left, at 0 kt.
  5. Because in its simplest form, Drag x Speed = Power. And drag is proportional to Speed squared, so power is proportional to Speed cubed. That's why the apex moves up the curve. Similar shapes, but the apex is not in the same place.
  6. I don't know why your books have separated the drag and the power. Normally, those curves would be called "Power required to overcome..profile drag / induced drag / parasite drag", and when combined, the axes of the chart would stay the same - but your book has twisted the next chart, the "total drag curve", around to put speed on the y axis, and left off the data between 0 and 60 kt. It is far easier to understand if it is on the x axis, like on the first "drag" chart. The Total Drag curve should be the same orientation as the curve "D-E Total drag" on the first chart. It won't be the same curve, because the drag is factored by the speed to get power, but the shape will be similar - see that they show that max endurance isn't at the apex on the drag chart, but it is on the power chart. Then it will be easier to see that the bottom of the power curve is where power required is least, (near point E on the drag curve), so it is the best endurance speed. It is also going to be very close to the best climb speed, if the "Power available" curve is also laid over the chart. When the gap between power available and power required is at its maximum, you have the most excess power to use for climbing. For range, it is a line drawn from the origin to be the tangent to the curve. The line is close to the curve over a spread of speeds, so it might be more convenient, for some other reason, for the manufacturer to nominate a speed that isn't at the exact tangent point. Rotating those second and third curves doesn't appear to make any sense. (Waiting now for Helonorth to make his usual attack on me. Come on, you know you want to...)
  7. Good for you Nate, having a wife who actually displays some interest is a bonus. I was teaching a student in his own B206, and when it came to the navigation phase, he put his wife and 2 kids in the back seat. We flew into gorgeous scenic areas, stayed at a unique underground hotel, flew more the next day, and back to his home city. When we were running the engine down, I asked him "What was the most important thing you learned on these flights?" His wife jumped in and said "READ THE F***ING MAP!!" Perhaps I may have said that a couple of times...
  8. Have a couple of trial flights, and visit more than one school for these flights. Simply having degrees and being able to read a manual won't be what gets you through. I have had doctors, lawyers, money market specialists, and plumbers, all of whom thought it would be a good move, but who all realised after 20 or 50 or 70 hours that they just didn't have what was needed to be a chopper pilot. Smart as heck, but some were unco-ordinated, or lacking physical dexterity, or just were too busy in their chosen fields to devote the time needed to know the stuff. There even was one retired B747 captain, who owned his H500 and flew it on a private licence with 700 hrs already, who wanted to progress to commercial levels. But this man, used to giving orders to his crew, found that he just couldn't fly the aircraft, hold a map to navigate, and make radio calls all by himself. He went back to flying 747, and managed to plonk one down without having the nosewheel extended - incomplete checklist actions after an inflight engine shutdown.
  9. Go back a few years here and read the stories of r22Butters. He was a wannabe like you, paid all the money to get the ticket, though he didn't go to instructing. He tried REALLY hard to get work, picked up a few offers but realised he was just being used and spat out. He kept sort-of current by renting privately, but after many years of head-butting, gave it away, doesn't even post here any more. This is a serious leap of faith you are contemplating. Great if you reckon you have plenty to live off, the young kids must be in day-care if your wife is working (hope you factored that in too) and you will sure need to be dedicated to follow this long, twisting, pot-holed and often grass-covered path to a proper job. I was from the military path, and still caught the AIDS bug from all the time spent on the job instead of on the family. On the civil side, you work your guts for the boss, and he still treats you like something he stepped in. There was a post on another forum about a NZ R22 which crashed. It was time-expired, the engine was due an overhaul, the blades were timex, and no wonder it went down. The only good bit was that the owner was flying it at the time, but 5 minutes later he was to have a passenger on board. The margins are so thin in this industry that owners will look to cut costs anywhere. Anywhere.
  10. Works fine for me too, the red highlight to differentiate between editorial and adverts is good.
  11. Not many R22s can make it across the Atlantic. If he wants to visit Snotgobbler, Noo Joisey, then don't rain on his parade.
  12. Most aircraft will have a limit on winds for startup. It is generally best to start with the wind fairly close to the nose - and turbines don't like it up the backside either. In the rotor head are devices to protect the mast from inadvertent strikes from the bottom part of the hub. On the B206 you have the spring-loaded flap restraints, but once the blades are turning, the weights pull the stops out of play. If a sudden gust comes along, the blade will respond by flapping up as it comes into the wind, and the out-of-wind blade will flap down. Without the stops in place, the whole hub can bump the mast on the downside, causing damage. Hueys, on start-up, would usually have the crewman holding the blade as the engine winds up, then letting the engine pull it out of his hand to accelerate faster than if it was loose. Doesn't actually stop the problem, but reduces it. When shut down, the teetering blades are tied down at the back with the droop stops, underneath the hub, in contact with the mast, and secured. Stops the wind bouncing it around and causing damage. static stop.tiff flap restraint.tiff
  13. Shack is probably an unemployed 747 pilot now!
  14. A time-x aircraft, particularly an R22, is not in a safe condition.
  • Create New...