ANOTHER LESSON IN "BUMP TOLERANCE"

[pudestcon]

Bump Tolerance? You should have been out flying in Sydney tonight!

Bump tolerance? Get onto the board of RAAus and see if you can ride the bumps!!! Turbulent times eh?

Pud

 

 

[facthunter]

Aircraft don't stall by themselves . Pilots make them do it.. It's not snake oil. If you just sit here and leave everything alone it won't stall . Nev

 

 

[Sapphire]

Aircraft don't stall by themselves . Pilots make them do it.. It's not snake oil. If you just sit here and leave everything alone it won't stall . Nev

 

I guess you mean that if you trim the a/c for straight an level flight and take your hands off the controls it wont stall. Tried it a few times on a boring nav and the plane always wants to drop a wing and go spiral, which is natural.

 

 

[motzartmerv]

No, that's not what he means..;)

 

What was goin on Howard??

 

 

[XP503]

Drop a wing and spiral? Doesn't sound natural. Rigging might be out....

 

 

[Sapphire]

Drop a wing and spiral? Doesn't sound natural. Rigging might be out....

Trim your a/c for straight and level flight next time-see how long it stays straight and level hands off.[and feet]

 

 

[Guest Howard Hughes]

What was goin on Howard??

"Thuderbolts and lightning, very very frightening"...With apologies to Freddie.

 

 

[facthunter]

The point I am making is that the pilot stalls the plane by increasing the angle of attack by holding/pulling the stick back. IF you don't do that it doesn't stall. Nev

 

 

[motzartmerv]

"Thuderbolts and lightning, very very frightening"...With apologies to Freddie.

Galileo!!!!

 

 

[ayavner]

mamma mia! mamma mia!

 

 

[motzartmerv]

Trim your a/c for straight and level flight next time-see how long it stays straight and level hands off.[and feet]

Most aircraft in our catagory should have a lot of 'natural stability" by design. The more manourvarable the less stability, but most RAA acft should be reasonably stable.

Stability is something that is generally brushed over in training and its a shame as it has some far reaching implications, and an understanding of it helps other 'pennies' drop.

 

Nevs comments re stalling deserve a closer look aswel sapphire. An aircraft stalls for one reason and one reason only. Angle of attack being increased beyond the critical angle.

 

Turbulence, wind gusts etc can cause a momentary increase in very localized areas of the wing which could stall a small section of it for a moment, but the entire wing generally remains un effected. SUre, some chronic turbulence may actually stall an entire wing, but it would have to be some bloody severe bumps and we wouldnt be there anyway.

 

The pilot holds the stalling stick in his hand. As a rule, the wing can not stall unless the pilot puts the stick in the stalling position. While getting bounced about in turblence may feel horrible, the chances of a stall developing from it are 2 parts of bugger all, unless the pilot in his attempts to control it, pulls the stick into the stall position.

 

What is far more dangerous and much more likely to be encountered is wind shear.( Defined as sudden changes in wind speed and or direction) In our low inertia aircraft this can cause real problems that relate to the above statements re the stick position.

 

The problem is that windshear can degrade the airspeed quite rapidly. The pilot only needs to maintain the same picture in the windscreen, ie, the nose in the same place, but now with airspeed reduced, the nose staying where it is requires back pressure on the controls, which is increasing the angle of attack. So the poor pilot on approach, doing what hes been taught, holding attitude, the speed bleeds off, all he has to do to get close to a stall is maintain his attitude. This issue is far more insidious and problematic than getting tossed about in rough air.

 

 

[Sapphire]

The only issue I had with Nev's statement is if the a/c is trimmed way back and c of g is way back. No control movements by the pilot can put a/c in a stall. However, most of the time pilots put a/c in stalls. Solution-tell them not to.

 

 

[motzartmerv]

The only issue I had with Nev's statement is if the a/c is trimmed way back and c of g is way back. No control movements by the pilot can put a/c in a stall. However, most of the time pilots put a/c in stalls. Solution-tell them not to.

HHmmmm...If a wing fell off it would roll too..Not really relevant though..;)

Tell them not to.. if only it were that simple saph...

 

 

[Sapphire]

HHmmmm...If a wing fell off it would roll too..Not really relevant though..;)Tell them not to.. if only it were that simple saph...

 

motzart, thats a novel new way to roll an a/c-you are good at other things than writing classical music:keen:

 

 

[winsor68]

Galileo Figaro...

 

 

[Sapphire]

I googled that winsor. Arn't we all musical. I'll have to change my stage name.

 

 

[facthunter]

Sapphire , we could make it "for any GIVEN aircraft configuration, there is a stick position where the plane will be stalled". If the plane is too tail heavy you can stall the tailplane before the mainplane subsequently stalls. I was presenting a situation describing a principle that most stalls are caused by the pilot by the way the elevator control is used.

 

The conventional approach to stalls of maintaining height after power is reduced, is pretty benign. It is NOT enough to just go this far , because nobody really stalls a plane accidently doing what you do for training, with the exception of a three point landing in a tailwheel aircraft, where you do exactly that but from a height of about one inch, (or less) ha ha.

 

Another situation where the plane won't stall at all is if it is too nose heavy or there is not enough elevator effectiveness to get the angle of attack to be reached. A lot of pilots are really frightened about flying slow. It needs a healthy respect but not fear and the technique needs to be taught properly. nev

 

 

[ayavner]

After this weekend, i clearly need to work on my bump tolerance...

 

 

[flyerme]

After this weekend, i clearly need to work on my bump tolerance...

 

 

[greybeard]

I managed to barf my way through most of my dual navs over summer in Perth a few years ago ( well, nearly 20 years ago ). I didn't seem to have the issue solo or during my PPL test.

 

I'm in the process of getting back into it and I'll be interested in how I cope after 10 years off.

 

 

[Guest nunans]

On the topic of bumps. When i fly around my area i find the bumps extend up to the cloud base and above that the air is smooth. Often the base is between 4 and 8 thousand in an inversion on an otherwise fair weather day. Is this typical of conditions in south and western australia also? before anyone jumps on me i'm not talking about flying above more than four octas. Rather scattered cumulas for example. i'm contemplating flying an aircraft from west to east coast and i'm trying to find out the most comfortabe time of year etc to do it.

 

 

[greybeard]

I've also flown above the inversion layer for a smoother ride. It's just those days when you can't find the layer before reaching 10k feet

 

It's not all bad, you just need to plan your flight times a bit better over summer. It's when you get those magic days of calm air and can get the trim perfect and then fly around by moving your body where you want to go to. I call it airborne motor bike riding

 

 

[Guest nunans]

Yep, that is fun. I don't think it works as well in the heavier 4 & 6 seat ga aircraft but it's easy in an ultralight.

 

Planning the flight times is probably the go but if I'm trying to fly from the west to east coast and i only fly an hour in the morning and an hour in the afternoon it might take me a while, maybe i'd be better off to wait 'till cooler weather.

 

 

[greybeard]

I did the airborne bike riding in a GA registered Skyfox I suspect that i'd need to go on a bit of a fatten up diet to ensure I had enough ballast to navigate a conventional GA aircraft in the same way. Mind you the larger GA plane I flew were a bit more tolerant of the bouncing around.

 

 

[Head in the clouds]

Planning the flight times is probably the go but if I'm trying to fly from the west to east coast and i only fly an hour in the morning and an hour in the afternoon it might take me a while, maybe i'd be better off to wait 'till cooler weather.

As part of my work I used to ferry a fleet back and forth seasonally between North of WA and North Qld. West to East in November and East to West in February so it was always very hot and there wasn't the luxury of just flying a couple of hours a day. When the weather was very unstable the inversion layer would ascend rapidly and be into the Flight Levels by about 10-11am so the best thing was to be airborne at first light which meant having all the fuelling and loading done the night before. We always aimed to be at the overnighter by early to mid afternoon because if CuNim was going to develop into lines of storms and become a barrier, at least you had time to divert without having to worry about end of daylight as well. Or if you had any mechanical trouble, there was time to be located before dark. In either circumstance it could make a difference to survival so getting the day's flying over as early as possible was the go. Leaving very early and being willing to go up to, these days in an ultralight or sport aircraft, A085, should mean you could get 6 or 7 hours of smooth air flying except during the descent and even with a long range tank that might be the best part of your endurance. Or your bladder's.

 

Also, it's much easier to get to altitude by climbing in the cool of the early morning.

 

We also used to carry full sandbags to bring the weight up to the MTOW because a heavy aircraft makes for a very much smoother ride in turbulence and the difference in fuel burn was negligible.

 

There was an earlier comment about stability of planes and that they would return to level flight if trimmed and left to themselves. I've flown many types, from ultralights to GA and they should/would all level the nose due to their pitch stability and as FH said, provided their loading is correct. But I have only ever found two which would keep their wings level (without an auto wing-leveller) and they were both ultralights with huge amounts of dihedral because they were derived from 2 axis machines and of course they had terrible dutch-roll tendency because of the excessive dihedral.

 

As I understand it wing-levellers (single axis autopilots) were developed simply because planes didn't return to laterally level flight after being disturbed by turbulence. Try it - if the controls are left completely alone in my experience the plane will invariably end up in a spiral dive.