There is a Coast Guard helicopter station fairly near my home and they seem to be quite busy with SAR and/or training. Why is it that the retractable landing gear usually isn’t retracted? I normally see the choppers at a relatively low altitude, I’m guessing 1500’ or less. Is there an SOP that says “Below X feet the gear will be down” ? On airplanes the gear is retracted right after take off to reduce drag so why not the same for helicopters?
Other questions I have relate to training. It seems that they always night practice in the same spot, a couple of miles off shore near a particular buoy. They fly out to a vessel with a blinking light and then hover low for an extended period of time. The last time I saw one it looked like the helicopter was motionless for half an hour, maybe more. I’m guessing that they are doing basket work. What are the limits of the auto-hover (horizontal/vertical gusts)? Does it compensate for the swell? How much fuel would they burn in 30 minutes of hovering?
I got to ride in one the Dolphins years ago as part of my work and was amazed how quiet it was compared to some of the other helicopters I’ve flown in. Is that due mainly to the number of rotor blades (4 vs 2 for the Hueys and Jet Rangers) and/or the ducted fan tail rotor?
I have no knowledge of the capabilities of auto hover. 30 minutes would be a good work test for pilots and they would improve quickly I would think.
Jumping in swimmers & hoisting out practice seems a likely answer.
I have no idea on the cycle rate of the landing gear. Short slow flights, they will not make enough difference in fuel burn to worry about. Makes landing without forgetting them much easier. Really not to good to forget them.
Also low altitude over land, an emergency autorotation = not nuff time to get them down and during said autorotation, the pilot need both hands to deal worth it. If high enough, there is time. Fixed wing aircraft usually have more time. But. You don’t see many retractable gear pipeline patrol aircraft either. All day on ‘short final’ altitudes means you might need them quickly. That’s why retractable aircraft are supposed to put them down when close to landing, not at the last second.
Need big chopper info and USCC info on the other stuff which will be here soon I bet.
The HH-65/MH-65 Dolphin (most are upgrades to MH-65D) uses a fenestron (ducted fantail) which in addition on minimizing drag losses on the tail rotor also limits flow in the vertical direction, which minimizes the acoustic interference pattern that produces the classical “whomp-whomp” sound of many helicopters. The relatively short main rotor blades and rate at which they spin also does much to push the developed acoustics to higher frequencies. The MH variants have an autohover mode that can hold a specified altitude for rescue operations (probably 50 ft to 60 ft) without direct pilot control, and has some limited anti-gust capability, but as with all rotorcraft there are significant restricitons on safe operation in gusty conditions even at relatively low windspeed, especially in microburst conditions. The Dolphin is a pretty small helicopter, and at least early in production was the lightest helicopter in its payload/range class. If I recall correctly, the mission range for USCG operations is 120 nmi with very limited loiter time.
On why the landing gear remains down at low altitude, this is strictly a guess but I suspect the vehicle has limited auto-rotation and glide capability and the undercarriage is minimally reinforced to keep weight to a minimum, so the gear is probably down to provide some protection against a hard landing due to engine failure or sudden loss od lift.
Slight tangent: in reading Sebastian Junger’s excellent The Perfect Storm, the thing I remember most about the Coast Guard rescue divers was their jaded, macho approach to their very dangerous work. Their adjective of choice in describing a particularly terrifying mission, diving into mountainous seas with no assurance of returning safely, was “sporty.”