Grant
Member Since : 2007
Posts(688)
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Power Checks

10-16-2009 07:07:09

Guys

I am putting together some safety material and I am interested, in what techniques pilots use to decide if they have sufficent power to get into and out of a confined area in an R22 or R44.

Detailed or not all descriptions welcome, particularly but not limited to those from instructors.

Gary

Replies

flybyranch
Member Since : 2015
Posts(19)
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10-15-2009 10:25:55
Gary, from personal experience teaching in the R44 II in Ocala FL, I can take the Raven II at 95 degrees, 70 percent humidity, 2000 DA (ish) and full fuel, Pilot = 175 Lbs, PAX = 180 Lbs and have 2 inches left. This will get me over a 50ft obstacle in a vertical climb. Put an extra person in the back at 170 Lbs and I'm at 26 inches and still able to climb vertical and clear the 50 ft obstacle no problem.

Haven't got stuck in a hole yet and don't want to try....

Hope this helps your report.
Rick
Gary Spender
Member Since : 2015
Posts(15)
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10-16-2009 06:04:24
Jeff

Thank you, a very logical approach if you ask me.

What I am hinting at is a a procedure we use in the UK, to assess the power margin available for take off or landing.

We teach something like , fly at min power required speed (53kts in an R22) note the MAP, calculate the 5 minute limit and then pull it to make sure then engine is working as advertised.

Dependant on the difference between these two figures gives you an indication of the performance you can expect in that location.

I have noticed we sometimes have wildly differing terms for stuff on each side of the Atlantic so I may have asked the wrong question !

There are some fairly obvious flaws in the procedure but most instructors I have spoken to cannot see them until pointed out, so the reason I am asking for info is too see what if anything you might do in addition to a simple MAP check.

My problem with the procedure (assuming the gauges are working properly) is that whilst a check like this in a turbine with a Torque gauge does indicate a power margin (because of the relationship of Power, RPM and Tq) whether the engine is on spec or not, with a piston it doesn't because MAP isn't Power.

Your thoughts ?
flybyranch
Member Since : 2015
Posts(19)
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10-16-2009 06:10:42
Gary, I know if I am hovering IGE at 24" that the other two inches will get me over a 50' obstacle in FL summer with 2 x PAX at 170 lbs and full fuel.

So the checks I use are hover power and making sure I have the two inches for vertical climb. Obviously temp, humidity, DA, weight and wind are all factors.

I hope this helps.....

Rick
jabr800
Member Since : 2008
Posts(134)
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10-16-2009 08:32:12
Gary,

I like Rick's answer.
He's basically saying he won't try it, unless he knows he has more than hover power available!
Of course he's IGE when he checks hover power, and goes outside that window (OGE) when lifting vertically, but that's where he feels at least 2 inches of extra available manifold pressure, takes care of everything.
That's about as good as anyone can put it I think?
Take Care.

Jeff Abrams
N222JA, R22 Beta II
Ocala, FL
Gary Spender
Member Since : 2015
Posts(15)
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10-16-2009 10:14:17
Thanks guys.

Anyone else want to say what they do ?

Gary Spender
Member Since : 2015
Posts(15)
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10-17-2009 02:26:12
Rick

Thats the kind of thing I am after, but with a bit of additional information, how do you know if you have sufficient power to get into a confined or high altitude area, what do you check ?

GS
jabr800
Member Since : 2008
Posts(134)
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10-17-2009 02:57:32
Gary,

I'm an Ocala, FL guy like Rick also, however I spent almost 4 years at KAPA, Centennial Airport, South side of Denver, CO, with my at the time Brand new Beta II. Elevation was 5,866msl. On summer days of 95 degrees plus, the machine would be working real hard with Density Altitudes of 10,000 or so.
As an old guy of over 20,000 hours in the air (about 1,100 in copters), I played it real cool.
I generally would go out a day or two early via car, and scope out the area for all the safety aspects.
I expect this isn't quite what you want to hear, but it did work well for me.
If I thought it was doable, I would then fly an approach into the place solo, early in the day for best temperatures, and usually minimum wind. If things were comfortable, I would then consider a very lightweight passenger and minimum fuel on the next attempt.
It worked well and no bad things ever happened. I always had an escape route out of the place on landing, and takeoffs, I would always keep in the back of my mind, the other guy can always get out if necessary and I would pick him up a short distance down the road as he would start walking.
I'm sure this is stuff you already know, but it kept me safe.
By the way, as to the power check issue, at these elevations, you simply used everything you had, which on a real good day, you might get near the max. manifold pressure, but because of the altitude, you often didn't.
The most important thing was being smooth with the machine, and smart with the brain (don't try something that obviously is beyond your capabilities or the machine's)! I guess that falls under the preflight planning part of the FAR's, obtaining all available information before flight?

Jeff Abrams
N222JA  R22 Beta II
Ocala, FL
choppedair
Member Since : 2015
Posts(45)
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10-17-2009 06:19:17
First off, know the hover charts, check them before you fly and know what you are working with before you try anything stupid. I use to ask my students what our OGE and IGE hover ceiling was for our flight based on temp/weight. If they had no idea, we didn't start until they looked it up. The charts are not accurate and performance varies a lot by aircraft, but they are a good place to start.
Here is what I always did in the R22. Fly over the spot at 53 kias (least amount of power required), 500 agl with carb heat down, note the manifold pressure used. Calculate the pressure altitude at the spot, estimate temp on the ground and calculate the manifold pressure available. Use that difference to calculate your reserve power. 1-3" MP is a low IGE hover, 3-5" was OGE, 5"+ was a vertical climb. Something along those lines.
Obviously the less power available, the more shallow the approach should be, and the larger the landing/takeoff area should be. Never approach/takeoff steeper than needed. Clear the skids by 10-20ft in a confined area, the extra 10 knots of speed is more important than another 20-50 feet.

The real simple (and most effective) way to figure things out, and what I do now in the R44, is to simply check power available, and pull an out of ground effect hover over the spot. If you can't hold a hover out of ground effect, better have a lot of room and a smooth surface. If you can barely hold a hover OGE, give yourself some room to be sure you can approach and takeoff with ETL, keeping in mind the wind (if any) will be at a lower velocity below a tree line. If you have a couple extra inches, you can make a vertical climb. If I know I have to make a vertical climb, I will even try it briefly from my OGE hover to see what kind of climb rate I will get.

I hope that makes sense and helps you out a little.
Gary Spender
Member Since : 2015
Posts(15)
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10-17-2009 11:42:13
It does and it does.
MLH
Member Since : 2007
Posts(99)
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10-18-2009 09:00:20
The HOGE method is my choice as it factors in all variables as they exist at the location. If it won't hover OGE at 500 AGl with some left over as a safety factor, it's a no go. Since a large percentage of where I fly is heavily forested, I try to do the check above a non confined area where I can safely auto to a landing if need be.
choppedair
Member Since : 2015
Posts(45)
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10-20-2009 02:30:09
The HOGE method is my choice as it factors in all variables as they exist at the location. If it won't hover OGE at 500 AGl with some left over as a safety factor, it's a no go. Since a large percentage of where I fly is heavily forested, I try to do the check above a non confined area where I can safely auto to a landing if need be.

Exactly, no questionable math involved. It either works or it does not. Although just because I can't hover OGE does not absolutely mean I can't get into a spot either. Some of the R22s I use to fly could not hover OGE near sea level with student/cfi and fuel, yet we used them all day long for off airports.


There is something I like to practice with students when we have excess power. I will find a good confined area where we won't bother anyone, that we can use over and over. I will ask them to land there and take off again, noting how much power they use and what kind of take-off/approach profile they use. I will also ask them to hover in ground effect and notice how much power is required. Then I will ask them to approach/depart again, but giving them a de-rated MP number to work with (usually in between the power they used on their last take-off and the power required to hover in ground effect). We will talk about their options for departing/approaching and how to get every bit of room and lift available for a given power setting. Once they have done their second approach/take-off with limited MP, I will have them try to get into and out of the spot with 1" more than it took to hover in ground effect. If the wind is right and the student is really smooth on the controls, you can often get out of a confined area only using the power it took to hover in ground effect.

This not only teaches them how to get in/out of difficult areas, but shows that you do not need to pull the collective into your armpit and climb like crazy to get out of most areas. It teaches them a safer approach/departure while putting less stress on the machine and leaving more buffer for unexpected conditions.
John S
Member Since : 2012
Posts(11)
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09-02-2012 08:31:30
The HOGE technique used high above your confined area will tell you a lot.  If you can't HOGE and your confined area is a tight place that requires a HOGE type approach or takeoff then it is not for you.

Takeoffs can be a challenge too.  Just because you safely got into a confined area ok doesn't mean you won't have problems getting out of there.

Best technique in a hover hole is to go straight up slowly and surely.  You will run out of ground effect at about 10 to 15 ft.  So really watch your MAP and performance at this point.  If you have a good margin (2 inches or more) and are climbing just fine thru 15 ft and above than you are good to go.  If not enough power, you will probably just stop in a hover at about 12 ft even at your max available MAP.  Pulling any more power at this point will just result in a loss of rpm.  So if you stop dead at 12 ft at max available chart MAP for your conditions,  you will need to land back carefully and download somebody or some things. 

The maneuver taught in flight schools, max power to clear a 50 ft obstacle, is a good coordination drill for students, but not to be used in the real world to get out of tight spots.  In fact it is a set up for an accident.
No One
Member Since : 2018
Posts(232)
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11-08-2012 08:36:56
My first post here, so please be gentle :)

Personally, I don't like the HOGE technique to be taught to student pilots. I really wouldn`t feel to comfortable knowing that a low time pilot is taking his friends for a ride in his brandnew R44 (probably full of fuel as he is afraid of being short on fuel) and starts hovering out of ground effect in lets say 500ft AGL. It's an accident to happen.

I teach my students (in a Hughes 300 that is) to approach the confined area as steep as necessary but as shallow as possible. I have them reduce their speed to slightly above ETL with no climb nor descent. Check your required manifold pressure and add another 3 ". If you are below your max t/o power you are good to land and, what is even more important, you are good to get out there again.

I don`t have too much experience instructing in a R44 (none in a R22) so I haven't had a chance to check my procedure on that type but it should work as well.

Frank