Approach Techniques

[r22butters]

I saw the Sporty's video "So you want to fly Helicopters" recently. It says is there, that some pilots like to fly their approaches holding 60kts until 60', then they bleed off airspeed correspondingly to altitude, i.e. 50kts and 50', 40kts and 40', and so on.

 

Do any of you do this?

 

I tried it once, and it didn't work out so well. Holding 60kts down to 60' feels uncomfortably fast, with too high a rate of descent, especially on a 'steep approach'. "Settling with Power" just seems way too easy to get into.

[SkidKid]

I tried it once, and it didn't work out so well. Holding 60kts down to 60' feels uncomfortably fast, with too high a rate of descent, especially on a 'steep approach'. "Settling with Power" just seems way too easy to get into.

 

 

Please explain how you can get into settling with power by holding airspeed up? I think you are confusing two basic approaches. A steep approach cannot be, by its nature, a fast approach. If you have descent rate problems, bring the nose back a bit more and adjust the collective accordingly.

 

The goal is to end up in the same position relative to the intended point of landing every time, no matter how you get there. The approach mentioned in the video is one that will keep you out of Settling with Power, reduces LTE possibilities and, as long as you make all approached INTO the wind, you will never have to worry about SWP.

[RockyMountainPilot]

Please explain how you can get into settling with power by holding airspeed up? I think you are confusing two basic approaches. A steep approach cannot be, by its nature, a fast approach. If you have descent rate problems, bring the nose back a bit more and adjust the collective accordingly.

 

The goal is to end up in the same position relative to the intended point of landing every time, no matter how you get there. The approach mentioned in the video is one that will keep you out of Settling with Power, reduces LTE possibilities and, as long as you make all approached INTO the wind, you will never have to worry about SWP.

 

Skidkid,

 

To put the ball back in your court, please explain how a steep approach cannot be a fast approach? What is it that allows someone coming in faster at say 5 degrees, but slower at say 50 degrees? Most steep approaches are done too fast IMHO.

 

Speed doesn't make an approach shallow or steep. It is a ratio of forward speed and vertical speed. Both can be too fast or too slow.

 

Butters,

 

My rule of thumb is never come in more than 30 degrees. It is impossible to enter VRS at 30 degrees or less. To answer your question, I begin slowing down when it feels comfortable. I don't use any numbers and I don't even look at airspeed or ROD. Rotor RPM and available power is the only thing that I really keep a close eye on. For a normal approach, I start slowing down at a point that allows for a smooth coordinated transition to a hover. For a confined area, I approach a point above the LZ at an angle of no more than 30 degrees. I terminate at an altitude above all the obstacles. 50 feet or 100 feet. Whatever it takes. I then perform a near vertical descent of about 85 degrees at a very slow rate of about 100 FPM. I like to move forward a bit so I can still see where I will set down. If you go straight down, you might end up on a small tree, or steel fence post.

 

The key is to fly at a level that makes you feel comfortable. If it isn't comfortable to you, then you are doing something wrong. Take your time and make everything deliberate.

[apiaguy]

I wonder if what the video was describing was a shallow approach where you basically enter under the height velocity curve and perform what ammounts to a quick stop but not quick... if that makes sense. I fly this approach often when I'm landing over a runway or other large open area. Decent to about 60-100 feet then slowly letting the aircraft bleed off speed as it slowly settles until termination. I like this approach... it makes me feel like I'm ready to put it on the ground at any point if I have a problem since I am already set up in an air-taxi.

[CharyouTree]

Skidkid,

 

To put the ball back in your court, please explain how a steep approach cannot be a fast approach? What is it that allows someone coming in faster at say 5 degrees, but slower at say 50 degrees? Most steep approaches are done too fast IMHO.

 

Speed doesn't make an approach shallow or steep. It is a ratio of forward speed and vertical speed. Both can be too fast or too slow.

 

A fast steep approach has another name: autorotation.

[Pohi]

Once the final approach has begun, there is rarely a need to look inside the helicopter imo. If a pilot is basing the approach off a altitude and an airspeed, there might be problems.

 

If there is a 30 knot wind, then this pilot will never be able to land unless they start going backwards do decrease airspeed

 

I base the approach off of relative ground speed. Once final approach has begun, a relative walking pace of the terrain moving below the helicopter (assuming there is no pinnacle) will be enough to ensure that the approach will decrease speed all the way to the landing point.

 

Or, ever since I got my airplane license I just keep 60 knots until the skids hit the ground. I go through the pads on the skids every few months, but no issues with settling with power yet.

[Pohi]

A fast steep approach has another name: autorotation.

 

Autorotation is the state of flight where the main rotor system is being turned by the action of relative wind rather than engine power.

 

That would have to be one heck of a fast steep approach, like getting down to a clearing after a bad Mexican lunch.

[SkidKid]

Skidkid,

 

To put the ball back in your court, please explain how a steep approach cannot be a fast approach? What is it that allows someone coming in faster at say 5 degrees, but slower at say 50 degrees? Most steep approaches are done too fast IMHO. Correct! Most are done too quickly, but mostly in the vertical descent speed, thus placing one in the VRS environment. If one is doing a steep approach at a high AIRSPEED, one tends to overshoot the LZ, thus my statement that it is inherantly a slower approach. Also, if one is descending too quickly in a steep approach, there is the strong possibility of an overtorqe at the bottom, unless in the autorotative state.

 

Speed doesn't make an approach shallow or steep. It is a ratio of forward speed and vertical speed. Both can be too fast or too slow.

 

Butters,

 

My rule of thumb is. . . . . never come in more than 30 degrees. It is impossible to enter VRS at 30 degrees or less. . . . . Interesting observation.

The key is to fly at a level that makes you feel comfortable. If it isn't comfortable to you, then you are doing something wrong. Take your time and make everything deliberate.

[Wally]

I saw the Sporty's video "So you want to fly Helicopters" recently. It says is there, that some pilots like to fly their approaches holding 60kts until 60', then they bleed off airspeed correspondingly to altitude, i.e. 50kts and 50', 40kts and 40', and so on.

 

Do any of you do this?

 

I tried it once, and it didn't work out so well. Holding 60kts down to 60' feels uncomfortably fast, with too high a rate of descent, especially on a 'steep approach'. "Settling with Power" just seems way too easy to get into.

 

Get out the calculater- 60' agl at 10 deg approach angle = 345.53' from impact. I say impact because you're about 3.5 seconds from your point of intending landing at the initiating speed. The only way you're going to hit that point is to to crash into it, probably with a honking rotor overspeed.

 

Initiate your approach at a comfortable, safe height, and do a gradual decel all the way down. You should 'settle' onto the terminating hover without any apparent flare at any point of the approach.

[RockyMountainPilot]

Get out the calculater- 60' agl at 10 deg approach angle = 345.53' from impact. I say impact because you're about 3.5 seconds from your point of intending landing at the initiating speed. The only way you're going to hit that point is to to crash into it, probably with a honking rotor overspeed.

 

Initiate your approach at a comfortable, safe height, and do a gradual decel all the way down. You should 'settle' onto the terminating hover without any apparent flare at any point of the approach.

 

 

Good point Wally. My motorcycle does 0-60 in a little under 3.5 seconds, so that is some very hard deceleration to save that approach. I think the video is trying to say make a smooth gradual deceleration, but they never did the math to see that 60 knots at 60 feet isn't practical.

[r22butters]

SkidKid Posted Yesterday, 17:14

Please explain how you can get into settling with power by holding airspeed up?

 

If you hold your airspeed up, you will have a greater rate of descent in order to stay on your intended glide path, especially on a 'steep approach'. If you are not careful, you could easily bleed off too much airspeed before your rate of descent slows to less than 300fpm, thus "settling with power".

 

I don't actually fly this way, I was just wondering what you all thought about what I had heard in the video.

Edited December 22, 2009 by r22butters

[RockyMountainPilot]

Butters,

 

If you keep the approach angle 30 degrees or less, you won't have to worry about VRS. 30 degrees is a lot. So, a standard steep approach of 15 degrees will keep you well clear.

 

Oh, and don't use the 300 fpm and 30 knots thingy. You should know at what airspeed and ROD your helicopter will encounter VRS for both max and minimum weights.

Edited December 22, 2009 by RockyMountainPilot

[IFLY]

50kts 500fpm

40kts 400fpm

30kts 300fpm

20kts 200fpm

10kts 100fpm

 

I use this as a general guidline modifying it for wind.

Jerry

[r22butters]

RockyMountainPilot Posted 58 minutes ago

If you keep the approach angle 30 degrees or less, you won't have to worry about VRS.

 

I have never flown with an instructor who wouldn't instantly jump to push the cyclic forward if I let my airspeed get below 30 while my rate of descent is greater than 300fpm, so I am very interested in knowing where you got your info.

 

I generally use "slower than ETL, and ROD of 300fpm", when explaining VRS during BFRs and recurrent checkouts, however as I stated above, when flying with instructors, they always use 30kts. I know the R22 will be ok at slower speeds.

 

I just can't see holding 60kts, while keeping a 10/15 degree angle, all the way down to 60', it just doesn't "feel" safe, but then again, I only have about 1,300 landings

[RockyMountainPilot]

Butters,

 

You are probably flying with inexperienced instructors. Ask them if a helicopter at a light weight or heavy weight will enter VRS at a lower ROD. Most will say a heavier weight.

 

I have a formula and graph that I will post when I get a chance.

[RockyMountainPilot]

50kts 500fpm

40kts 400fpm

30kts 300fpm

20kts 200fpm

10kts 100fpm

 

I use this as a general guidline modifying it for wind.

Jerry

 

 

Wouldn't it be easier to just say you use a 6 degree approach angle?

[apiaguy]

I think of it as the exact opposite of a "normal" take off for you flying a R22...

How high are you when you are taking off and are near 60kts? It's the classic R22 take off to zoom down the runway at low altitude to stay under the height/velocity curve.

Now imagine doing that in reverse... what do you have? A quazi quick stop.. as explained before.

If you look at the VSI you'll have issues with your approaches unless it is an IVSI. The lag is sufficient to make you believe you're in danger of settling w/power on all kinds of approaches... just takes experience to visualize ground speed... and know your wind.

[JETTSET99]

I think butters watched this clip of the guy coming in hot downwind one time to many!!!

 

[RockyMountainPilot]

I think of it as the exact opposite of a "normal" take off for you flying a R22...

How high are you when you are taking off and are near 60kts? It's the classic R22 take off to zoom down the runway at low altitude to stay under the height/velocity curve.

Now imagine doing that in reverse... what do you have? A quazi quick stop.. as explained before.

If you look at the VSI you'll have issues with your approaches unless it is an IVSI. The lag is sufficient to make you believe you're in danger of settling w/power on all kinds of approaches... just takes experience to visualize ground speed... and know your wind.

 

The HV curve only applies for takeoff or cruise flight. It doesn't apply for descent.

[apiaguy]

DUH.

point is trying to explain the OP's idea of an approach technique

[r22butters]

JETTSET99 Posted 27 minutes ago

I think butters watched this clip of the guy coming in hot downwind one time to many!!!

 

Ya, that would make me want to "walk it in", damn! They show a similar video at Robinson, with an R44, and a rooftop.

[JETTSET99]

I think if you read the Rotorcraft Flying handbook you get the best technique and explanation for normal and steep approaches, Sporty flying video is not what I would look for flying advice or to find better teqnique,but I think you figured that out when you tried their jesus juice

[IFLY]

Wouldn't it be easier to just say you use a 6 degree approach angle?

 

Yes but you can't see that on an instrument installed in a R-22. Until the student can get their approach under control (to a spot out in the desert they have never been to before) it keeps them out of trouble and helps them make a go around decision earlier if needed. Steep approaches come later and use a normal approach until you get to the obstruction that requires it to be steep.

 

Jerry

[Goldy]

I wonder if what the video was describing was a shallow approach where you basically enter under the height velocity curve and perform what ammounts to a quick stop but not quick... if that makes sense. I fly this approach often when I'm landing over a runway or other large open area. Decent to about 60-100 feet then slowly letting the aircraft bleed off speed as it slowly settles until termination. I like this approach... it makes me feel like I'm ready to put it on the ground at any point if I have a problem since I am already set up in an air-taxi.

 

 

I use this often when coming into a runway (not a helipad). I like it as well, you use about 12 inches of MP, bit of flaring at the end to slow down, and you can set it right down without pulling any power if you time it right.

 

Goldy

[kodoz]

I have never flown with an instructor who wouldn't instantly jump to push the cyclic forward if I let my airspeed get below 30 while my rate of descent is greater than 300fpm, so I am very interested in knowing where you got your info.

 

Robinson also recommends the 3-2-1 rule (maybe it's even in one of the Safety Notices...?), but p160 of Principles of Helicopter Flight shows a graph of ROD vs KIAS, with Angle of Descent overlaid. According to that diagram, steep approaches at Angles of Descent >50 degrees, a rate of descent >500 fpm, and airspeed

 

Smooth deceleration and a low rate of descent has it's merits, namely less power to hover required at termination.