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The wind knocked out of my sails today..

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The wind knocked out of my sails today..

Old 12th Mar 2016, 14:28
  #21 (permalink)  
 
Join Date: May 1999
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This nonsense of adding gust factor increments for light aircraft needs to be stamped out. It is totally unnecessary for low inertia, low wing-loading aircraft and the last thing you want to be doing in gusty conditions is fannying about in the flare because your approach speed was too high and the aeroplane is still flying whilst you move further from the trimmed approach speed and lose finesse as a result.

Unless the POH advocates a gust factor increment, just use the normal approach speed and ignore the BS spouted by pilots of larger aircraft trying to influence light aircraft flying with large aeroplane techniques.

There is ample fat built in to the POH speed for landing at the planned mass - no need for '5 knots for the wife and kids' or other garbage.

When I was HoT at an RF, I inherited a load of nonsense which included:
  1. Flying the approach at POH +10
  2. Adding 5 KIAS if 3 or more PoB (PA28)
  3. Adding 1/3 gust factor above 15 kts

We reviewed the speeds and changed the checklists. As a result we had no more damaged nosewheels, no more drifts off the RW and students learned how to land more easily.

As for 'wing down', that's something weird and American - I never found it very pleasant to fly in such an unbalanced manner. So in everything I ever flew, I used the 'crab' technique - everything from the Chipmunk to the Vulcan to the Phantom to the VC10 to the PA28.

Use the 'point and power' technique, fly at the correct approach speed and 'de-crab' at the same rate as you flare - it's very simple.

And anyone advocating 'kicking the aircraft straight with rudder' deserves a good kicking themselves!

Last edited by BEagle; 12th Mar 2016 at 20:50.
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Old 12th Mar 2016, 14:35
  #22 (permalink)  
 
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Use the 'point and power' technique, fly at the correct approach speed and 'de-crab' at the same rate as you flare - it's very simple.
Wouldn't de-crab during the flare make the aircraft drift? In a tail dragger that could be a problem.
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Old 12th Mar 2016, 14:43
  #23 (permalink)  
 
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I've found some types prefer crab, some wing-down, both techniques are fine.

The end of crab is effectively into wing down to land aligned with the runway anyhow, surely.

I do find it interesting that we've got a lot of quite experienced people, with some very different views on something that should ideally be pretty fundamental and universally agreed.

G
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Old 12th Mar 2016, 15:08
  #24 (permalink)  
 
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Wouldn't de-crab during the flare make the aircraft drift? In a tail dragger that could be a problem.
Not if you time it correctly.
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Old 12th Mar 2016, 15:32
  #25 (permalink)  
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I didn't expect to start a debate about techniques.. but always good to hear from more experience.

I was trying to come down at 70 kts as taught and crab into wind.. and then should have straightened out at the last minute before touch down (had I have made it down).

Flying with an instructor here during the checkout - they teach - wing into wind, and keep the nose aligned with the rudder - which is side slip - but that clearly didn't work for me.

At a maximum back home in the UK in a strong wind - the instructor during my PPL said you should not be faster than 75 knots as the piper in a cross wind will land at 70kts if you keep the power on.

Reviewing my notes from yesterday the wind was 140/16 G **something** couldn't quite work out what the AWOS recorded message said..maybe my hearing or the thicker accent.

Anyway I'm glad I canned it and made it back in one piece to my base.
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Old 12th Mar 2016, 15:48
  #26 (permalink)  
 
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That is one of the joys of PPRuNe when it's working well.

What type were you flying? 70 seems high for most singles, particularly solo.

I'd suggest that numbers aside, you may not have had the aeroplane as well trimmed on approach as you needed it to be - if the speed was creeping up, assuming a serviceable aeroplane (I've known the occasional pitch trimmer that crept, but it's unusual, and not usually that fast) then the increase in speed can only be because either the aeroplane's not properly trimmed, or you're inadvertently pushing forwards on the yoke.

G
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Old 12th Mar 2016, 15:56
  #27 (permalink)  
 
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doing in gusty conditions is fannying about in the flare because your approach speed was too high and the aeroplane is still flying whilst you move further from the trimmed approach speed and lose finesse as a result.
But Beagle thats landing technique which is wrong I would suggest that in strong crosswind and gusting conditions the last thing you want to be doing is hanging around in the flare full stop.

Anyone with excess speed above the stall on landing who floats is indicative of landing technique being wrong.

In some conditions its better to fly it on

Pace
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Old 12th Mar 2016, 15:58
  #28 (permalink)  
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G - it was a PA 28 161 Warrior II.

Yes, I think a number of things were out of aligned hence the judgement call.

They did say to me the real learning comes after the PPL has been issued!

Thanks for all the replies!
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Old 12th Mar 2016, 16:18
  #29 (permalink)  
 
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Your go-around and divert was clearly spot-on.

Speedwise: Warrior II POH approach speed is 63 at MTOW. Solo at half tanks, probably about 59. Even with another 5kts "for the wife and kids" (which I'd not advocate) that's 64kts.

I'd suggest practicing working out, and trimming for, the book approach speeds. You should find it makes a big difference to both your stress levels and landings.

G
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Old 12th Mar 2016, 16:22
  #30 (permalink)  
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I had full tanks and I weigh about 121 lbs.

All a learning experience.

It scared the c**p outta me been shook like a rag doll but I learned from it to tell the tale.

Ta!

Scoobster
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Old 12th Mar 2016, 18:43
  #31 (permalink)  
 
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(Just in case you don't know - multiply the MTOW approach speed by the square root of [actual weight / MTOW] ).

I wish I weighed 121lb !

G
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Old 12th Mar 2016, 20:26
  #32 (permalink)  
 
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I'm told "They" don't like you to 'wing down' an airliner
risk of dragging a wing mounted engine pod on the floor you see.
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Old 12th Mar 2016, 20:51
  #33 (permalink)  
 
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I prefer crab in a Pa28, but always sideslip in a DR1050. With the latter, I get over the runway, stir the controls as required to keep in middle of runway, aligned along it, until into-wind wheel touches. Then keep as straight as possible until speed is lost.
Not possible with a bumpy grass runway, where I would have to go elsewhere if I was losing control effectiveness as speed dropped.
I've tried holding off in a gusty crosswind, but as speed dropped, I was unable to maintain position and alignment, and went around.
If speed over ground seems low on approach, expect windsheer. Higher airspeed won't lead to landing far down the runway in that situation.
Just some controversial views of a basic PPL mainly flying a light taildragger.
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Old 13th Mar 2016, 11:17
  #34 (permalink)  
 
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G

Having thought about your post I have to say I am not clear on the science of what you are saying
I presume you are arguing that no extra speed should be added for gusts and windshear and Infact increasing speed is negative above 1.3 Xs the stall in a given configuration.

Turbulence windshear is not a condition confined to landing but obviously something which can be encountered at altitude and at cruise speed in the form of severe turbulence or inadvertent CB intrusion
Normally experiencing such turbulence means an instant reduction in speed to VA
We have to dissect two aspects here loss of control authority and danger of stall at two slow a speed and over stressing the airframe
It's a bit like a high powered speed boat crashing into waves or riding waves but aeroplanes don't float )

As stated I experienced airspeed leaps of plus and minus 25 KTS and it doesn't take much maths to work out the danger at being at a normal VREF

Turning to light GA Pistons I don't think the FAA or EASA would stipulate 50% of the gust factor added to VREF if they didn't have good reason to do so
Are you suggesting and I am not clear on this that at higher speed windshear has pronounced effect at higher speeds or that at higher speed there is risk of structural damage by holding a slightly higher speed than VREF

And in simple cause and effect terms as I am pretty thick )) I would be too scared to test that theory with a normal VREF and 25 KT plus and minus for real )

Pace

Last edited by Pace; 13th Mar 2016 at 12:26.
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Old 13th Mar 2016, 19:49
  #35 (permalink)  
 
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Turning to light GA Pistons I don't think the FAA or EASA would stipulate 50% of the gust factor added to VREF if they didn't have good reason to do so
Do they?

Can you give authoritative references?

G
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Old 13th Mar 2016, 21:26
  #36 (permalink)  
 
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Don't EASA stipulate that balloons should be landed into wind?
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Old 13th Mar 2016, 21:53
  #37 (permalink)  
 
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Originally Posted by abgd View Post
Don't EASA stipulate that balloons should be landed into wind?
Ah, but where on a balloon is the "front"?
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Old 13th Mar 2016, 21:54
  #38 (permalink)  
 
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It's the bit that's into wind, obviously.

G
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Old 14th Mar 2016, 04:02
  #39 (permalink)  
 
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I do find it interesting that we've got a lot of quite experienced people, with some very different views on something that should ideally be pretty fundamental and universally agreed.
I often find that pilots who consistently handle crosswinds without difficulty are using the same technique, but describe it differently.

Successful pilots who say that they 'kick off the drift' or 'decrab', are almost invariably using these terms to describe the process of converting, in the flare, from a crabbed approach, (flying in balance with the aircraft heading somewhat into the wind to maintain the centreline) to a side slipping touchdown, where angle of bank (aileron) maintains the aircraft on the centreline, and yaw (rudder) maintains the runway heading.

I find that if you teach this technique for all landings, then dealing with crosswinds ceases to be a problem.

... is that there's enough margin in everything to mean that it doesn't matter as much as we think - another is that gust response and control authority scale about the same (which probably is true) that they pretty much cancel each other out.
I think you're right on both these points, Genghis. If people would just stick to the speeds in the POH, they would be generally better off than making up their own.


I think he 'speed' thing is a misunderstanding in two parts. There is the gust response/control response factor on the approach, but the more important for crosswind landings, is the touchdown speed.

The faster your touchdown speed, the less the drift for a given wind.

For instance, with a crosswind of 20kt an aircraft touching down at 20kt will have a very scary drift angle of 45 degrees, whereas, another aircraft touching down at 200kt would hardly notice a 20kt crosswind at all.

It follows, therefore, that the faster you touch down in any aircraft, the less effect any crosswind will have.

The problem with landing at higher speeds, is that it requires a lower nose attitude on landing. In the old days, this wasn't a huge problem, as the tailwheel aircraft of the time simply raised their tails, and did a 'wheeler landing'.

For modern tricycle types, this isn't an option, as 'flat' landings damage nose-wheels, and cause 'wheelbarrowing'. We have all seen the results of that.

There is, however, a way of landing such aircraft at higher speeds, whilst still maintaining the same landing attitude, and that is to reduce the flap setting.

A Warrior landing without flap, but in the same lading attitude as one landing with 3 notches, will touch down around 10-15kt faster. (Remember those flapless landings you last did during your PPL?) This will reduce the drift at touchdown considerably.

Note: You don't need to increase the approach speed beyond the normal flapless speed for this, so the landing distance should be no more than for a flapless landing.


MJ

Last edited by Mach Jump; 14th Mar 2016 at 04:30.
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Old 14th Mar 2016, 11:11
  #40 (permalink)  
 
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G

Here you go as requested a link to an FAA article
You will also find a specific link within the article for using higher speeds with gusting winds

http://www.faa.gov/news/safety_brief...TheNumbers.pdf

Pace
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