chopper question

[IMJ345]

I couldn't find this info anywhere else. So I thought I'd come here. (USMC, OCS, PLC Jr Grad).

How do high winds affect the flight of a helicopter (specifically, a civilian MEDEVAC type helicopter)?

And does anyone know how far out a typical MEDEVAC chopper will fly? What's it's AOR?

Thanks.

 

[BigIron]

It depends on what you mean by high winds. High winds are good in a sense if they are behind the helicopter; which calls for a nice tail wind, or ground speed.
Bad for the opposite, which is a headwind.

Obviously the higher the wind gusts, the rougher it makes the helicopter fly through the air. It also depends on what the helo mission is. If extended hovering is required, then higher winds make this extremely difficult to hold a steady position over a spot. It also depends on where the wind is coming from on a helicopter whether in forward flight, or in hovering flight. If there is too much wind coming up the aft or side of the helicopter, then the aerodynamic forces on the tail rotor might cause excessive blade pitch and the helo could possibly lose tail rotor authority at some point.

As far as rescue helos, I really don't know, but based on their average size, I wouldn't say they could go for more than a few hours without refueling. I am sure there are some civilian/commercial helo guys on here that could further elaborate.
Hope this helps.

 

[Gatordev]

Big Iron sums up most of it. One thing to keep in mind about "high winds" while in a hover is that they can actually help you if you can keep them on the nose. More wind makes the helo think it's flying faster, so the blades become more efficient. This, in turn, requires less power needed to hold the hover. I was dropping some CG guys on a rock off the coast of Kuaui, and had a good 30-40 knot headwind/updraft hitting the helo. At one point, I was showing 30% Tq (which is almost what you have at idle), lowering the collective, and still climbing.

I'll leave the civilian numbers to guys like Chuck, but on the military side, the range can vary depending on model. The Blackhawk doesn't have as much gas as a Seahawk/Jayhawk, which can go 3-5 hours depending on the model and config. Figure 120 knots for airspeed (max cruise). I'm sure the -53 dudes will laugh at that, plus they, along w/ the Pavehawks, have those pointy things on their noses.

 

[JIMC5499]

And does anyone know how far out a typical MEDEVAC chopper will fly? What's it's AOR?
Thanks.

My information might be a little dated but I know that Lifeflight in Western Pennsylvania wouldn't ordinarily go farther than a 90 minute round trip from where it was based. They have several helos based throughout the area and unless one of them had mechanical problems 90 minutes rount trip was the rule. If there was some kind of emergency then it was different. I pumped 1200 gallons of Jet A into Lifeflight's BK117s one night. Figure 100 gal. per bird per fueling. Some tornados had hit and they were transferring patients between hospitals. Of course they have Dolphins now.

 

[ChuckMK23]

I couldn't find this info anywhere else. So I thought I'd come here. (USMC, OCS, PLC Jr Grad).

How do high winds affect the flight of a helicopter (specifically, a civilian MEDEVAC type helicopter)?

And does anyone know how far out a typical MEDEVAC chopper will fly? What's it's AOR?

Thanks.

Winds affect a rotorcraft much the same way that they affect an airplane - groundspeeds tends to be the biggest issue though. Stormy fall and spring weather in the Ohio Valley we would see 40-50 knots of wind at times. Gusty conditions can be a pain for the med crew in the cabin.

In the trusty BK-117 ( the most common EMS helo in th eindustry), a full bag of fuel was 184 US Gallons - which was roughly equal to 2+45. 20 min reserve leaves 2+25, cut in half is 1+12. 130 KTAS cruise, and 15 minutes of ground idle time gives you a mission radius of about 115 NM for a scene flight. The more typical inter-hospital transfer mission profile (go pick up patient at small rural appalachian hospital and bring back to trauma center) can be much longer. You drop off your crew at the destination hospital, then fly solo to a local airport and gas up, then return to hospital helipad in time to load patient and crew and blast off back for home.

Oh and figure 3 starts and shutdowns in between. Lots of starts and shutdowns in EMS. We teach "cockpit flow" and not physical checklist. Checklist for single pilot ops is for checkrides and maintenance flights.

 

[Cyclic]

How do high winds affect the flight of a helicopter (specifically, a civilian MEDEVAC type helicopter)?.

On a C/MH-53E...
Headwind=fast as hell....Tailwind=Fvk'n fast....Wind Gust=Bah!! :icon_smil

And does anyone know how far out a typical MEDEVAC chopper will fly?

As far as you like...until something breaks or there are no more tankers.

By the way...the Army has Choppers,

WE have Helos.