Landing Helos

[SemperApollo]

Since I got carried away in a different thread but still was confused, I'll ask it here:

Do all helos land on the backside of the power curve?

If anyone has some good stories or just general knowledge, feel free to add it to this thread.

 

[gregsivers]

I fly helos and I don't even know. Just shows how much of that generic aero stuff I remember.

 

[BigIron]

Are you talking on the front side of the power curve? As a helo gets slower, or hovers, it takes a lot of power to do that (front side). On the opposite side, as the helo maxes out in speed, it also takes a lot of power (back side of curve). So, if you are talking about a hover type landing, then yes a lot of power. There is a no-hover landing (less power required), and finally a running landing (the least power required) as the helo stays in transational lift.

 

[MasterBates]

Yes, A helo's power required vs airspeed plot looks like a "U"

Example for the 60B...

Tourqe Required at flat pitch on ground ~20%. This is the power needed to just turn the rotor system and accessories.

Torque required to hover (in ground effect) 70-85% depending on GW, DA, etc

Hover out of ground effect can be 85+ %. Sometimes, especially when hot & heavy, you just don't have the power to do this.

"Bucket" Airspeed is ~65 KIAS. About 45% torque.

Vh. Max Airspeed. About 130-160 KIAS depending on GW & DA. 106% Torque.

 

[Gatordev]

Master's break down does a good job of showing the real-world data points and where they fall out on the curve.

Hover out of ground effect can be 85+ %. Sometimes, especially when hot & heavy, you just don't have the power to do this.

However, there are those crazy times. I've been in a climbing, out-of-ground effect hover at 25% Tq.

 

[MasterBates]

How?

 

[Gatordev]

40-50 knot wind + Rock/cliff face + hoisting some coasties. Lots of collective movement w/ the gusts, but you could steady up most of the time. Challenging but in a good way.

 

[MasterBates]

Ahh, we had similar stuff during JTF rita. Indicating 50-60 Kt in a coupled hover, but at about 45% torque.

 

[SemperApollo]

When the wind is gusting like what you were talking about, do you use the automatic hover or do you have to do it by hand?

 

[gregsivers]

When the wind is gusting like what you were talking about, do you use the automatic hover or do you have to do it by hand?

Depends on how much its gusting. We can dial in velocity vectors for each of the 4 axes to compensate for wind, but if its out of the limits I figure you'd do it manually. Again, I'm still in the RAG so take this for what its worth. (maybe nothing)

 

[Gatordev]

When the wind is gusting like what you were talking about, do you use the automatic hover or do you have to do it by hand?

I did it by hand. You can react faster than Otto can, even w/ its Gust Alleviation. When I would do SAR jumps (which is a pretty benign environment in a bay), I'd fly the approach to hover manually and then once stabilized, switch over to the computer sometimes. Sometimes I'd just hover manually because I was bored.

Now night time is a whole different ball game. Computer all the time, everytime for doppler approaches. The only time I wouldn't use it was doing night tactical take downs. Things are just moving too fast (120-150 knots, 2500 FPM descent rate). Then once in a hover, click on the hover mode. Of course, this is w/ goggles and a platform to hover off of (the boat you're next to), so that helps.

 

[hscs]

2500 fpm descent in a takedown???????

 

[SemperApollo]

Just to clarify: a takedown is when the helo comes in really fast and flares at the last second and (at least in the MH/SH/UH-60 series) touches down on the tailwheel?

 

[Pags]

Just to clarify: a takedown is when the helo comes in really fast and flares at the last second and (at least in the MH/SH/UH-60 series) touches down on the tailwheel?

not too sure about the takedown, but the maneuver you're describing sounds like a tactical approach.

 

[Gatordev]

Just to clarify: a takedown is when the helo comes in really fast and flares at the last second and (at least in the MH/SH/UH-60 series) touches down on the tailwheel?

No, this is when dealing w/ non-compliant boardings. You start w/ a high descent rate and obviously slow it down at the bottom. Works very nicely and they never see you coming.

Exhibit A: http://www.news.navy.mil/search/display.asp?story_id=15308