Interesting experience

[GraemeClarke]

Gidday, I had an interesting experience a couple of days ago. I was flying up a valley into wind to go over a small pass into the next valley. With the down flowing wind, and my lack of power I was unable to get enough hight to get over the pass. I turned away about 200 ft and level with the pass to get more hight. I was faceing away from the pass when the airspeed went to zero, the nose went down at a steep angle, and I headed downwards. I dived for maybe 4 seconds. The airspeed suddenly went up to 80mph, and I leveled out. It was a bit like I would image a stall would be like in a FW. The wind was about 10 k, with very little turbulence. My machine is CLT with a HS.
It gave me a bit of a fright. I'd be interested in comments.
Graeme

[PW_Plack]

Sounds like a wind current that was rolling, tucking under, coming over the pass. Glad you're here to tell us about it!

[Heather Poe]

"Mountain Flying Bible Revised" by Sparky Imeson is a great source of information on this topic.

[brett s]

http://www.atsb.gov.au/publications/2005/images/mw_turb_001.jpg

[scottessex]

Sounds like wind rotors similar to currents rolling around boulders in a river.

[Roundwing]

Whoop Whoop
Windshear!
Pull Up!
Whoop Whoop
Windshear!
Pull Up!

[birdy]

I just got back from checkn how many fences this rain has knocked out, and my wild ride started before i even got airborne.
With a stiff breez [ bout 60kmh] wipn across the strip at 50 degrees from the right, the rotors were at 290rpm before i even started the roll, then i opened the 914 and with a bit of a tail wag down the strip i reached lift off speed within 10'. Broke ground and just started to let it yaw into the xwind wen i hit a dead hole and fell back to the ground. After sum more tail wagn i tryed agin with abit more AS and at bout 20' AGL, same thing, but i only kissed the deck this time and then went streight up. As i climbed above the tree line i hit the stronger wind, and was climbing like a rocket with negative ground track.
Started think bout then that this was go'n to be abit ruff today, if the f^%$# TO has any bearing on wots ahead. ;)

Ya gota remember Graeme, you gota keep an eye out for anythn that'll cause virtical rolls, specialy in a margonal machine.

[GraemeClarke]

Thanks Birdy, Been meaning to ask you did you name the feral after the movey, or the other way round. Whats the history of the machine in mad max.
I'm sure your right about the rotor thing, what interest me is the way my machine reacted to it.
Graeme

[Douglas Riley]

We all know that flying in a steady wind (a big block of moving air) is aerodynamically no different than flying in no wind. Rapid transits from one moving block to another that's going in a different direction are a different story. The aircraft must "catch up" with the speed and direction of the new block of air before the steady-wind rule again applies. If you're continually, and quickly, moving from one block to another, you're always playing catch-up.

A stable aircraft will try to get into sync with whatever air mass it's in at the moment. Your gyro tried, by dropping its nose when your transit into the new block of air resulted in 0 airspeed. That was a stable response. No doubt you fell out of that particular block and into one moving in a different speed and direction, hence the sudden 80 mph.

Downwind of an obstacle like a hill, the turbulence likely was a rotor -- a horizontal whirlwind. Trying to fly a straight-line path through one of these is bound to cause a series of wind shears that the aircraft can't keep pace with. In strong mountain winds, they are very dangerous and can bring down big aircraft. The top of the rotor moves in the wind's direction, and the bottom moves opposite -- same as an eddy and backwater in a river. The bottom might have been the source of the 80 mph, since you were flying away from the hill and the wind.

If you get on the windward side of the obstacle, you can often find smooth lift that can make you think aliens are drawing you into the sky with a magnet. The leeward side really stinks (or sinks), however, unless you fly way above the maximum height of the obstacle.

[Aussie_Paul]

The best idea is to make a decision early to circle to gain altitude if you don't think you can make it.

Hi Graeme.:wave:

Aussie Paul. :)

[Steve McGowan]

While in AZ, workin with GBA I'd get to fly anywhere from 20-40 hrs a week between instructing and test flying the Sparrow Hawks..
One morning I left out after a few hours of instructing,so about 9:45 I headed to Wickenburg, flying time off 4132Y, I was going some 38 miles north.

Beautiful flying in Az.. Nothing in your way except cactus and rock outcrops. That is if your 50'agl and below..

After getting to Wickenburg and talking to a few mediflite pilots about the SH, I deceided it was time to head back to Buckeye..
It was close to noon, thats BAD due to thermals and down drafts.. And wouldn't you know it. I hit a down draft about 10 mins outta Wickenburg..

Now mind you, Wickenburg is a quiet lil town at about 2400msl atop a long ridge line. That is some 1500' higher than the surrounding desert floor to the south....The airport itself runs UP-Hill/or down, and as you climb out on the uphill side there is still a few hundred feet to clear the ridges around the west side.

I had cleared the ridges and started south when the downdraft caught me. Suddenly the VSi went to 1500fpm drop and I'm close to the rocks as I clear the peak.. Now I'm dodging cactus and rocks with 50 mph Airspeed and a lotta dropp in my face.. Time for the Sub to go to work..

About three miles later, down the ridge I ran into the bottom at 30'. then the airspeed topped well over 100..
It was a real quick way down to say the least.. The last 30 or so miles was really slow compared to the down hill run..

When I got back to Buckeye Jim Mayfield and Terry Brandt ask why I was in so early..I told them about my ride,, they just laughed and said
"we'll see Ya in the morning.."

Now flight suits are hot and pourous in 100 plus temps,, needless to say,

I had a very distinstive odor about me that I hadn't noticed,, You figure it out....:noidea:

Az is the best flying times of my life, if Ya ever get the chance to visit there,, DO IT.. You'll never be sorry....

But stay the Hell away from Wickenburg, at Mid-day..

Oh Yea, thanks Jim and Terry..... I Love Ya guy's..:usa2:

Steve

[WHY]

Hey Steve

What would happen to a high thrust line machine (even with a high time pilot) if it had encountered this same situation ?

Tony

[birdy]

That would depend on wot the pilot did Tony. I'v hit hundreds of um, but i dont fly around half asleep either. ;)

[Steve McGowan]

The gyro was a Sparrow Hawk,, HTL with a 2.5 suburu 160hp engine.. 30' Vanic blades/Sport Copter.. And I was flying it, as best I could at the time.
I should say HOLDIN ON.:hail: and Yes BIRDY,, I got caught sleepin......

What would have happened if I hada been a few seconds later on the throttle,, I woulda slammed into rocks, boulders and cactus going down the ridge.

Air acts much like water, if you've ever water skied or watched a surfer.. If and when the water gets on the front/top of the board , or the air gets on the top of the Blades/ GYRO.. U CANNOTT Back a BOAT Up-Stream
Ya lose lift or you just get into a negative/downward force of air. It can also Happen in REVERSE..

It's what FixWingers call WINDSHEAR sometimes... and low flying aircraft are very prone to it..Especially around ridges/tree lines or when the thermals rise/desend.

Even a 777 can get in one... Hope I answered your question,,, and I'm very sure someone can and will correct me.. Happy if they do...;)

[birdy]

The gyro was a Sparrow Hawk,, HTL with ..........
I thought the SH was CLT, or at least close to it?

[Douglas Riley]

There IS a difference between "catching" the bow of a boat or surfboard and going to zero G in a gyro. The difference is that you have the same medium (air) above and below you in the gyro, while the boat/board rides the boundary between one medium -- air -- and another, thicker medium -- water. It makes a big difference. A rotor won't "catch."

In fact, instead of "catching," a rotor will try to fight back to pos G. As you lose rotor thrust, the trim spring has nothing to oppose it and it tries to haul the torque tube back. If you get to negative thrust, the bar will be pushed down even harder. As long as the rotor thrustline is aft of the CG, any negative thrust from the rotor will also push the tail down.

If a gyro DOES tumble forward in zero G, it's not because of any inherent tendency of autogyro rotors to do that. Rotors don't (on their own) "catch," "pitchpole" "bunt" or whatever you want to call it. The tumble isn't caused by the rotor at all, but by some other force on the frame. It can be HTL, a pod the drags the nose down, floats, etc. It MAY even be possible for a machine with extreme LOW thrustline, no HS and very light blades to get a forward flip going and just keep going from inertia alone. But all these things are mistakes in airframe layout.

A lot of people (especially non-gyro people) think there's some secret evil tendency in a gyro rotor that makes it want to flip upside down. 'Tain't so. We just have some bad airframe designs out there.

[Hognose]

Sounds like you got caught in a rotor or a lee-side downdraft, as in Brett's illustration, Graeme.

I concur in Heather's recommendation of Sparky Imeson's books (I have two of them, Mountain Flying and Mountain Flying Bible. Yes, they are useful here in the Northeast US). I'll check and see which one I liked better (I confuse the two). I bought them from Amazon.com in 2001 or so.

Imeson also has a video which is very good, although the first 20 minutes are just pictures of planes flying, landing, and taking off in beautiful mountain settings, set to music! I was getting grumpy by the time the instruction finally started. Mind you, I only watched this on a friend's TV and I don't have a TV, and don't know if it is available on DVD (I have a VHS copy).

Lee-side downdrafts will eat your lunch. One of the biggest scares I got was flying with a flatland Black Hawk crew who did not respect mountains and repeatedly flew into lee-side downdrafts (yes, they can overpower even that machine). I hated being medevaced because I had to go through those same rocks at night in the chopper, but that crew was mountain-savvy and it was a joy to watch them at work (hey, if you gotta ride the chopper, enjoy the ride, right?). It turns out they were a California National Guard crew who have day gigs on life flight helos and fly in the Sierra all the time.

New Zealand strikes me as a place where one would need to learn all he could about what happens when air masses cross mountains. I don't know how many times I've heard someone say, "It's windy down here, but look at that cloud standing still, there's no wind on the mountain," and point at a lenticular cloud. That cloud is actually being created and destroyed on the fly, by wind pressure passing the mountain at 60 kts or more, and flying anywhere near it ... well, it's not recommended.

cheers

-=K=-

[automan1223]

There are days it is blowing and days it is not but that never allows one to go to sleep. Flying around eastern NC there are jets of air that can be at 500' on a relatively calm day and those jets of air flow in and out of the creeks that lead to the river. They will surprise you when you least expect it.... It is as flat as can be around here I can only guess what mountains can do to you...

Among the more experienced pilots here (it has been discussed from time to time) I think they will all agree that some of the high time pilots that are no longer with us may have gotten caught in the rotor trap. Most dangerous around the edge of tree lines, open fields and water.....

Power can save you if you have the juice and the altitude.

2cents....

Jonathan

[StanFoster]

Jon athon: good points about the rotor traps. My pictures show nothing but flat terrain under me where I fly....but those ditches I run get a lot of respect. On windy days...you can feel the turbulence a couple of hundred feet up and down wind.

I stay on the upwind side on windy days....I have an ultralight buddy that just about got flipped over near the ground by one of those tree induced rotors. Of course an ultralight is more sensitive to such...but even my heavy gyro can get a surprise if I am asleep.


Stan

[GraemeClarke]

Gidday All,
thanks for the replys. I have spoken to a friend who watched me go down. He said that I went down sideways at first while still parallel to the ridge. So it would seem I got into a rotor. The area I was flying in is near where Paul B got hammered going from the north Island to the south. Its definitly mountain flying. I look out of my window acros a bay to a 4,000 ft hill. I will try and get one of the books hognose mentioned. It really is fun flying around here though.
Graeme

[Chopper Reid]

Hey Steve

What would happen to a high thrust line machine (even with a high time pilot) if it had encountered this same situation ?

Tony

Answer, you get a rough ride but it isn't a big deal, however, I had good training and worked my way into the rougher stuff. I would recommend low hour pilots to get up high and keep out of the messy stuff.

[Ga6riel]

indeed it can happen in reverse
its a phenomena known as ridge lift to glider pilots
north of here in the flinders ranges, that are perpendicular to the dominant westerly inland flow, and one of the longest global features that is so positioned. Flying on the weather side of the range allows a glider to point nose down for speed, and yet experience lift via ridgelift, therefore travelling at Vmax velocity while not losing altitude, this balanced by the AoA.

A local pilot made the world record for distance using the power of ridgelift for some 800+ km. The ride is quite bumpy due to many slight variations untill you get up around Vmax where the speed evens out the differences. Big gliders ca turn a lot of speed in these circumstances, as they are comparitively heavy to enable them to punch through the air; a quality known as penetration.

If they get into trouble, ie losing altitude fast, and where circumstances of a successful landing at speed are slight to say the least. They can ditch the water ballast that is kept for the purpose of maintaining penetration as a function, but being a disposable load in an emergency.

On the other side of the ranges, the lee side, the opposite condition exists, that of constant downdraft

[Chuck_Ellsworth]

At the risk of being put down by a few here who believe me to be evil may I make a suggestion?

Air is a fluid with the capacity for mobility and expansion and contraction through temperature and pressure changes.

Air is quite similar to water in its behaviour when moving over an uneven surface.

One interesting way to better understand the mobility of air is to watch it move and change direction and speed.

This is easily done by studying clouds and watching them change shape and direction of movement as they build or decrease in intensity.

Of course the most impressive visual of air movement is watching a thunderstorm cloud shape change and move, or the ultimate visual for air movement is the tornado.

C.E.

[dragonflyerthom]

Air is a liquid with the capacity for mobility and expansion and contraction through temperature and pressure changes.

Air is quite similar to water in its behaviour when moving over an uneven surface.

Your statement is correct there Chuck but Air is fluid not liquid. Water is liquid and Air can become liquid if it is cold enough. Your a good man Chuck and I would love to hear some of your stories. I know you have several you can relate.

Thanks Chuck in advance. About the only story that I can relate is getting too close to a thunder storm in Florida. Put me on my side in my 172. I won't go close to one of those ever again.

[Chuck_Ellsworth]

" Your statement is correct there Chuck but Air is fluid not liquid. "

Ooohhh, fu.k I was in a hurry and did not check what I wrote close enough.....

...sorry, and thanks I went back and edited it......

I'm sure you realize I know the difference and made a dumb mistake in wording.

I shall check my posts a lot closer from now on. :Cry:

[Aussie_Paul]

At the risk of being put down by a few here who believe me to be evil may I make a suggestion?

Air is a fluid with the capacity for mobility and expansion and contraction through temperature and pressure changes.

Air is quite similar to water in its behaviour when moving over an uneven surface.

One interesting way to better understand the mobility of air is to watch it move and change direction and speed.

This is easily done by studying clouds and watching them change shape and direction of movement as they build or decrease in intensity.

Of course the most impressive visual of air movement is watching a thunderstorm cloud shape change and move, or the ultimate visual for air movement is the tornado.

C.E.

Chuck, :suspicious: have you ever flown one of these clouds subject to air currents :rolleyes:to prove that you have the required number of hours and experience to make such rash statments re air currents and clouds.:whoo: :whoo:

:sorry: :):)

Aussie Paul. :)

[Chuck_Ellsworth]

Paul, I can't answer that question because I did not take special training so I could regain control if I lost it in one of those clouds.

Does the AFS offer special training for thunderstorm penetration?

Now on a serious note.....

...the most impressive line of thunderstorms I ever flew through ( or rather found my way around ) was about 250 NM S.W. of Panama on the way to Ecudador in December of 1974, the American Airforce Radar operator in Panama told us he was painting the tops at 76,000 feet. We have probably flown through some that were as high or higher during flight throught the ITCZ in other parts of the world, but those TS tops were official on radar.

The most difficult flight I ever had was one night we flew into an active cold front without weather radar and our altitude was varying between 12,000 feet and 7,000 feet the lightening flashes were so brilliant inside the thunder storms we had to get the cabin attendant to bring us blankets to try and block out the flashes in the windshield and side windows.

That was such a difficult flight we never had a sexual thought for the whole time we were trying to keep the airplane right side up, or close to right side up.

[LARRYEBOYER]

Chuck. You are right . you are evel. But your post was right on. A rotor can be an interesting event. I got caught in mountain rotor on a windy day flying a Pterdactal ultralight. If I had had a chute, I would have thrown it, I had to ride it out. No aerorons to help. The aircraft just wanted to roll on its back. The dyhedrial in the wings prevented it from a roll on its back. finally flew out of it, but a new respect for the lee side of the mountain on a windy day. Oh did I mention I survived?And Chuck. I am evel too!!!

[Chuck_Ellsworth]

Larry, I don't mind being thought of as evil because I must have been born that way.

But what really hurts is not being skilled enough as a pilot to fly an RAF and make an educated analysis of how it handles stability wise without having Harry demand to know how much time I have on an RAF......you see in the world that I fly in non of us are trained to a high enough standard to understand something a complex and difficult to learn to fly as an RAF....according to Harry....

Maybe someday I will take some training from one of RAF's expert instructors and show all my colleauges in aviation that I have finally reached the zenith of being a real pilot.

Now there is an example of how evil I really am!! :lol: :first: :rant:

P.S.

Yes Larry, rotor like mixing on the downwind side of hills or mountains can produce turbulence beyond the ability of the aircraft and pilot to maintain control. One of the most interesting visual manifstations of mountain wave air behaviour is standing lenticular clouds, flying into that area of mountain wave turbulence can tear any aircraft apart.

[birdy]

Thanks Birdy, Been meaning to ask you did you name the feral after the movey, or the other way round
????????
Wot feral, wot movey?

[GraemeClarke]

Gidday Birdy
Your Machine which you call feral. The Gyro pilot character in Mad Max 2, (Mel Gibson) was called Feral. The machine looks like a Bensen with a "V" tail. There is a very interesting shoot of the gyro landing vertically into the fortifid compound.
Graeme

[Steve McGowan]

The gyro was a Sparrow Hawk,, HTL with ..........
I thought the SH was CLT, or at least close to it?

Ya Knows What I mean,, nOW Don't Ya.. CLT ULT HTL TLT whatever the heck

I didn't bust nuthin...:sorry:

I REALLY feel there is too much BULL KaKa...... be TRAINED CORRECTLY or

stay yo Ass on the ground.... Ya THANK....

Kinda like bein Swallered by A Great White.......:puke:

[birdy]

Dont know the machine your refern to Graeme, so i gess that means they aint related. :)
I call mine ferel, coz it is. ;)

I REALLY feel there is too much BULL KaKa...... be TRAINED CORRECTLY or

stay yo Ass on the ground.... Ya THANK....
Sorry i asked.................................idiot.

[C. Beaty]

Not the definition of feral Mr. Bird had in mind but perhaps the intended definition in the Mad Max movie:

fe·ral2 (frÆÃl, ferÆ-), adj.
1. causing death; fatal.
2. funereal; gloomy.
[1615–25; < L frlis of the dead, funerary, fatal]

[Ga6riel]

feral are sort of high end mongrel
the mongrel both lives longer and is more intelligent, or so the story goes
the feral is smart enough to think he can make it alone and usually succeeds
over generations they develop into a sort of super-race
and live out of reach of normal existence

[Doug Riley]

In the legal biz, there's an ancient term, "animalia ferae naturae." It means wild animals, but specifically those that haven't yet been corralled or shot. The inference is that they don't belong to anybody as long as they're still "ferae naturae." They own themselves.

Once they're brought under a person's control, they become his or her property. Birdy and his bird will never be tamed, so I guess they're both feral.

(It was -12 F. this morning outside my window. This leads the mind to wandering. Bensen Days better come soon...).

[C. Beaty]

The common meaning of feral, Doug, and the one Birdy most likely meant is: livestock, formerly domesticated that have escaped captivity and reverted to the wild state.

Thus in Florida we have feral cattle and hogs that escaped captivity and didn’t make to the dinning tables of their Spanish owners.

The longhorn Spanish cattle, over the years, have crossbred with scrub cattle and have developed their own distinctive appearance.

[ckurz7000]

Ahh, rotors, lenticulars and wave lift! These words are what makes a glider pilots's mouth water.

It's a great experience to go up in a glider during mountain wave conditions, keep your eyes outside watching the clouds and terrain and trying to form a mental image of what the air mass is doing and where.

Once you get cought in a bit of rotor and get through to the smooth wave you can't believe your senses!!! It's totally smooth and your VSI is pegged at 2000 fpm up. You point the nose into the wave, slow the plane down so that you are stationary in the wave and ride it like an elevator. In anticipation of this, you usually bring supplemental oxygen and warm socks because you can get up to 18000 feet real fast!

A great way to fly!

-- Chris.

[Harry_S.]

Ahh, rotors, lenticulars and wave lift! These words are what makes a glider pilots's mouth water.

It's a great experience to go up in a glider during mountain wave conditions, keep your eyes outside watching the clouds and terrain and trying to form a mental image of what the air mass is doing and where.

Once you get cought in a bit of rotor and get through to the smooth wave you can't believe your senses!!! It's totally smooth and your VSI is pegged at 2000 fpm up. You point the nose into the wave, slow the plane down so that you are stationary in the wave and ride it like an elevator. In anticipation of this, you usually bring supplemental oxygen and warm socks because you can get up to 18000 feet real fast!

A great way to fly!

-- Chris.



Thanks Chris.

That reminded me of when I took a few flights in a 2 place trainer, thinking I wanted to get into glider/sailplane flying.

One or two of the more experienced pilots would come to the strip with a lunch and some sort of fluid, get a lift up and be airborne all day, sometimes for 6-8 hrs. and return, to do it again the next day. They loved it.

Dearly Beloved would say, their wives probably were glad to have 'em gone for the day. :D


Cheers :)

[Steve McGowan]

Dont know the machine your refern to Graeme, so i gess that means they aint related. :)
I call mine ferel, coz it is. ;)

I REALLY feel there is too much BULL KaKa...... be TRAINED CORRECTLY or

stay yo Ass on the ground.... Ya THANK....
Sorry i asked.................................idiot.

Guess now I'm an Idiout.....

Thankyou...........:lol:

[GraemeClarke]

Maybe Aussi Paul will know the history of the gyro in Mad Max 2.
We have a wave here in NZ that glider pilots love. I wonder if you could fly it in a gyro? Go for a record maybe.

[ferranrosello]

Lots of wise and interesting things about mountain flight and turbulence have been said in this thread.

In my opinion the most important thing is that mountain flight in windy days is dangerous, especially if it is done without the proper knowledge. And I want add a new thing that has not been mentioned by now.

It is important to avoid flying in a valley centerline. It is much better to choose one of the sides. In the middle of the valley the wind speed is higher, turbulence bigger and... air density lower.

This reduces dramatically the aircraft performances...

Another important question when flying into valleys uphill, is that is needed a great concentration keeping our airspeed fast enough. If not, the reduced airspeed is a new problem which will reduce more the aircraft capability.

Ferran.

[birdy]

It is important to avoid flying in a valley centerline.

Wouldnt it be good if the world was perfect[ and friendly]. ;)
Unfortunately for me, cows usualy live in the middle of vallys, either coz thats where the sweetest feed is, or the sides are too steep or the vallys too narrow to be anywhere but in the middle. :)

But your right Ferran, the sides are always smoother, and if you pick the right side, you'll have good lift from thermals and you can coast along at idle.

[GraemeClarke]

The flying I have done around here is mainly in valleys with steep hills on eachside. I find I get less of a hamering if I stick to the middle. The wind tends to run up or down the valleys. There seems to be a lot more turbulence by the sides from the ridges and valleys. I also find that whole areas of the valley can be in lift, or sink. Its a bugger when you are flying up a valley and the cars are all passing you. Theres a thing around here that the helocopter guys are suposed to do called ridge flying. I talked to one guy and he said that what they do is fly along the windward side of the hill along the ridges. Ive watched them at my place, and they don;t seem to do that.

[greeny]

There are quite a few hills in my place (Switzerland), and since a fair amount of GA accidents are by foreigners who underestimate the dangers of flying in the mountains, flying in and across the alps in different conditions are compulsory lessons in our PPL syllabus.
During PPL training, you have to cross the alps at least twice at different days and land at different mountain airfields.
And you learn:
-> You NEVER fly in the middle of the valley.
If you fly on the sunny side, thermals may increase the usually poor performance of the engine at these altitudes. Yet the main reason is the extra space you gain that way if you have to turn around. And these valley can become VERY narrow.
-> You NEVER fly towards the end of a valley while climbing. The ground of a mountain valley may climb far faster then your plane will ..
-> You NEVER try to cross a pass with less than 1000 ft. of air below you. There is usually a hell of a lot of turbulence there and you want to be sure to have some reserve height.
-> You NEVER cross a pass streight ahead. You approach it from one side and cross it diagonally. That way you can always turn around and sneak away if things get too lively.
Can't be all wrong to take that into consideration if flying in such places.

[ferranrosello]

A wise lesson, greeny.
Thank you.
Ferran.

[GraemeClarke]

Thanks Greeny, all very logical.