May 24, 2008 at 10:28 am #513
I see military pilots landing in some pretty darn small LZs, some no wider than a two-lane street where large trucks have to slow to pass in opposite directions.
- What is the minimum recommended size for an emergency helipad?
- when approaching large structures, is it better to be sheltered from wind by the structure (landing in the lee) or upwind? Meaning, which side has the most turbulence?
I’m assuming the problem is two-fold. Landing upwind has the possibility of gusts pushing you into the structure, while downwind sacrifices the more predictale smooth flow of air currents, and causes unpredictable pockets of turbulent air.
May 24, 2008 at 10:09 pm #2363
- But which is worse?
Off shore oil platforms use helipads all the time. This is one of those questions were we just need to ask a helicopter pilot who ferries people around for the off shore industry, what the issues are. I suspect that there have been a few articles written up and posted to the internet even.May 25, 2008 at 4:09 am #2377
As a helicopter pilot, the farther away from large structures the better the airflow and less turbulence. But of the two options, I would far rather land upwind than leewind. It would enable me to maintain ETL and be able to use the available power to overcome and turbulence.May 25, 2008 at 4:23 pm #2378
This document outlines what precautions to take when putting an Helideck on some sea structure. And this UK air regulation body’s document explains how to design an helideck. Basically, you want the helideck to be as far as possible from anything else in order to minimize the interaction from the helideck’s environment. So that would be “away in the wind”.May 25, 2008 at 8:45 pm #2387
May 25, 2008 at 9:07 pm #2390
- I think the big issue is not the size of the actual pad, but how far on every side the helicopter will have to objects that the rotors can strike.
- I´m not a helicopter pilot, but I imagine that they always try to land into the wind. This would mean that there optimally should be no structures higher than the pad – as demonstrated by most actual helipads on top of buildings.
- WIth large structures on either side even if you could land the wind could potentially become more unpredictable, which can´t be good.
- An emergency helipad can be very small. This depends on the skill and/or bravery/insanity of the pilot.
- Book tip: “Chickenhawk” by Robert Mason. Mason was a Huey pilot in Vietnam, in the book he relates his experience. At one point he describes “enlarging ” a clearing in the jungle by cutting off branches with the rotor. At another point they practice formation flying with overlapping rotors…
Yes, they always try and land into the wind, and have little leeway for landing in other directions. The size of the pad depends on the size of the helicopter, from about 35 feet square for a small one to a hundred or so feet square for a large one.
The approach and departure paths need to be clear as well – while a helicopter can (under some circumstances) stop and land vertically it’s dangerous to do so: If the engine quits you have no options but falling. With forward airspeed you can ‘auto-rotate’ and at least crash softer. The approach should be about 3 degrees or less, in and out.
Trimming trees with rotor blades is not only risky (what if you break a blade? Goodbye!) but expensive. Mason wasn’t paying for the replacement blades, and they aren’t cheap.May 25, 2008 at 9:31 pm #2393
May 28, 2008 at 5:17 pm #2592
- True, but the question was (or, that was what I replied to at least ) regarding what could work as an emergency helipad.
- I would never suggest anyone try stunts like that if lives did not depend on it.
- Anyway, it gives some perspective on what level of control is physically possible, although not recommended.
May 28, 2008 at 9:27 pm #2620
- Why would it only be for emergency? I would think there would be regular flights.
- I’m not a pilot. I worked in the offshore oil industry for a number of years and have landed on platforms, barges, and ships a few dozen times. I’ve worked 3 recoveries as a diver. Jesrad’s linked document seems to be a pretty definitive answer.
- One of the things that will be valued offshore will be a sundeck. The helipad is the natural choice. People will go there to sun so just planning for it is the easy solution.
Indeed the flight deck on an aircraft carrier, when not engaged in flight operations is used for recreation all the time.November 24, 2009 at 5:24 am #8737
I’m a little surprised no one has suggested reviving flying boats for servicing seasteads. While they died out mostly because they became unnecessary with increasing range of land based planes and their greater operating expense; they would be much less expensive to operate between seasteads and shore than helicopters, especially between more distant seasteads.November 24, 2009 at 2:29 pm #8739
They died out because the economics weren’t there, partially driven by other options such as you mentioned.
Also, seaplanes are incredibly (more) expensive to build and maintain than land based aircraft. And, if the sea state is too high, landing is chancy and takeoffs near impossible. Finally, what do you do with a seaplane when it’s on the water? They’re big, ungainly and fragile. The civilian operators (good old Pan-Am, etc) landed them almost exclusively in sheltered bays or rivers and had a great deal of infrastructure to support them. The military operators had the same, and while they would occasionally land them on open ocean (especially smaller ones) they also would be willing to write off the airplane when the mission required it.
I won’t be wronged. I won’t be insulted. I won’t be laid a-hand on. I don’t do these things to other people, and I require the same from them.November 24, 2009 at 4:17 pm #8740
There are actually quite a few companies that are making small 2-4 person seaplanes that are very low cost and easy to fly. The Icon A5 is a nice one, as is the SeaMax. These are both small, sport planes so they are incredibly easy to fly and maintain. They can be had for under $200k USD.
As for mid-sized planes I like the Beriev BE-103, and another larger one is the Lake LA-270 Seafury.
A large example is the Beriev BE-200 (specifically the BE-210) which can transport up to 72 passengers. But now you are talking in the tens of millions of dollars so this is definately long-term.
Yes, these planes need plenty of space to take-off and land…around 200-300m for the smaller sport planes and over 2000m for the larger boys. And they need calm waters…although the bigger BE-200 can handle wave heights over a meter anything over 1m is rough landing for the smaller planes.
Having a large breakwater landing/take-off area would be required.November 24, 2009 at 8:17 pm #8742
Flying boats are expensive and expensive to operate – but less so than helicopters, especially over any significant range. I think they are also safer than helicopters, though substantially more dangerous than conventional commercial aviation.
On the open sea you would not want them to linger; land, deliver and pickup, and go. Quick turnaround would be essential.
I wasn’t thinking immediately, but long term, especially if seasteads were to catch on, they would make more sense than helipads.
Another possibility for reducing waves is have something like a biodegradable oil slick to temporarily calm the waters.November 24, 2009 at 8:57 pm #8743
I disagree. The numbers just don’t add up, even for a modern design like the BE-210. Max sea state for operations is 3? Thats considered a slight swell, .5 to 1.25 meter wave height. I’ve done a bit of open water sailing and conditions like that, even in the Caribbean, are rare. Also, the distance for water T/O of 2400 meters (call it 8K feet) under ideal conditions is pretty substantial. Range with a full load is 620 nm.
Note, this aircraft is very close to the ultimate design in seaplanes. I doubt that anyone is going to substantially improve them. The big Bombardiers don’t have the range, the cargo capacity, speed, etc.
Compare that to something like the existing V-22 Osprey stats, which will do nothing BUT improve (it’s new technology). Sea state? Call it 8. Range with full load? 890nm. It may be smaller, but other designs will get bigger.
I won’t be wronged. I won’t be insulted. I won’t be laid a-hand on. I don’t do these things to other people, and I require the same from them.November 24, 2009 at 10:54 pm #8744
It’s all about costs. I think each Osprey costs something like $100M USD and I don’t even want to imagine what the maintenance costs are on such a complex vehicle. In addition, you can’t even purchase Ospreys so if you want VTOL or STOL we will have to use helicopters.
I don’t think large amphibious craft will be viable for a long time…3000m is waaaay too much calm water and I doubt we will be needing to transport 70 passengers at a time.
I would suggest a handful of small amphibious craft like the SeaMax and one medium sized craft like the BE-103. A small breakwater landing/take-off area 600m is all you would need. Each SeaMax costs you, at most, $150k and the BE-103 will run you around $500-$700k and I’ve seen listings for $350k online. You are probably looking at $1.5M for your fleet of aircraft. Even if you factor in several millions of dollars for the breakwater you are coming in well under what something like the Osprey would cost.
The SeaMax fleet, each with a range of about 400nm, would be for rapid single-passenger transit or small critical cargo transit. You would use the larger BE-103 for larger groups or heavier cargo. A vast majority of passengers and cargo will move by ship…these would just handle the small percent of critical movement.
These aircraft don’t need any more maintenance than a normal land-based aircraft because they are made for marine environments. They are all watertight and made using composites or other corrosion-proof materials.
I also believe that helicopters are just far too complex, expensive, and require far too much maintenance to be cost effective. If you have more than one you are talking about multiple helipads that are wasted space…I don’t know what you are thinking but I’m not going to be sunbathing on a helipad if every few hours I’m gonna have to move as a helicopter comes in.
Of course, this all only works if you have a moored seastead since a breakwater is required. If your seastead is mobile then a chopper is the only way to go.
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