I'm not a pilot, but was wondering if someone may help.
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I'm not a pilot, but was wondering if someone may help.
I was trying to determine the approximate height that a helicopter can hover at for a prolonged period without being buffeted by the wind, and at such height what would be the approximate visible distance if you were to look out to sea. Many thanks in advance.
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The distance depends on quite a few variables but this will give you the maximum possible distance for any given height
Distance to the Horizon Calculator
For example:
1000' = 33Nm
5000' = 75Nm
10,000' = 106Nm
Distance to the Horizon Calculator
For example:
1000' = 33Nm
5000' = 75Nm
10,000' = 106Nm
I could see miles out to sea though, as it was a nice, clear day :-)
It differs from helicopter to helicopter. For a very still day where wind isn't pushing you around (that's hypothetical - above 2000ft AGL you'll always find some wind) you'd be limited by the helicopter's power and Hover Out of Ground Effect ceiling for your particular mass. For the distance part, you're welcome to crack on with the Tangent-Secant theorem in your own time but the answers will be theoretical maximums because real-world visibility will often be less than the earth's horizon. Especially above the sea, high humidity will give you either haze on a warm day or clouds and showers on less warm days, and you can't see through much of either.
Dan, if you can put why you want to know this into some sort of context it might help you get more specific answers.
Data point: a few months back I did a project where we sat at 5500' MSL (5000' AGL) with a 500lb camera system on the aircraft, for two hours, in one position. Well, "in one position" is relative as the aircraft wasn't autopilot-equipped so positional accuracy was limited to the pilot's ability, given limited reference points from that altitude. That was in an AS350B3e.
Given, there was some breeze up at that altitude, and it's unlikely you'd find no wind that high up. Like was mentioned earlier in the threads, all depends on the weather (and the machine).
Given, there was some breeze up at that altitude, and it's unlikely you'd find no wind that high up. Like was mentioned earlier in the threads, all depends on the weather (and the machine).
Data point: a few months back I did a project where we sat at 5500' MSL (5000' AGL) with a 500lb camera system on the aircraft, for two hours, in one position. Well, "in one position" is relative as the aircraft wasn't autopilot-equipped so positional accuracy was limited to the pilot's ability, given limited reference points from that altitude. That was in an AS350B3e.
Given, there was some breeze up at that altitude, and it's unlikely you'd find no wind that high up. Like was mentioned earlier in the threads, all depends on the weather (and the machine).
Given, there was some breeze up at that altitude, and it's unlikely you'd find no wind that high up. Like was mentioned earlier in the threads, all depends on the weather (and the machine).
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I was taught a big handfuls method whereby you take your ht in feet and the sq root of that gives the horizon in miles. I.e. 900ft high visible horizon is approx 30 miles away; 5000ft and horizon is about 70 miles.
Back in the late 60’s/early 70’s ( I think ) there was a test program called Project High Drink, wherein a USN SH-3 was to hover for extended periods at 10,000 ft, refueled by a flexible metal fuel line. Kurt Cannon was the project test pilot and Larry Russel a senior test engineer. They did the flying at the Augusta Ga. airport as I recall, but I do not recall what the purpose was. I do recall seeing pictures of the ground support equipment, fuel line on a huge reel etc. They did a bunch of flights, but that’s all I can recall.
John,
It is a little foggy, but I think it was Jim Sherry who was there for a while who told me that eventually the tube failed into many pieces and rained down without hurting anyone. I don't know if it was filled with fuel. If it was it must have been a scary situation. I think the idea was to use the helicopter as a sensor platform.
It is a little foggy, but I think it was Jim Sherry who was there for a while who told me that eventually the tube failed into many pieces and rained down without hurting anyone. I don't know if it was filled with fuel. If it was it must have been a scary situation. I think the idea was to use the helicopter as a sensor platform.
Thanks for the history Al M. You have better memory on this one than I. There were two Sherry brothers as I recall, Jim and I think Maurice, both very good folks. I recall that there wasn’t a long list of guys wanting to get into that test program, to put one aspect of the discussion in perspective, delicately. You know, one of those situations where one didn’t want to show real interest.......
Last edited by JohnDixson; 28th Jun 2019 at 12:17. Reason: wording
Well if it takes 1 atmosphere to push water up 34 feet .. about 4.6 psi / 100 ft; it isn't a hard calculation. about 460 psi. 2 miles of pipe must have been a bit heavy though.
14.7psi / 32.2 feet = ~4600psi at 10,000'. A bit less for fuel with a relative density of less than 1.
(I feel vaguely dirty doing that in imperial units)
