Turbulence speed
 

Just curious as to what other pilots out there use as a base to start reducing speed back to the A/C's turbulence penetration speed?

For me if on A/P I reduce pwr hence speed if the A/P struggles to maintain certain parameters. Patient requirements also apply at times.

Someone out there will know the C210 turb speed? 119 kts? Damn I used to hate that, very little holds those wings on...yeeeek:}



Wmk2

normally when things start to creak and groan, then i'll bring it back from Vne :}

For me. the older the airframe, the lower the turbulence speed. Not based on any science, just a healthy fear of the unknown. I would rather it stalled than broke.

I don't have a gucci autopilot, however I wait for telltale signs for what I know is coming. Eg. fly from Essendon to Latrobe Valley in a strong northerly. You are at 7,500ft no dramas, then descend through 4,000ft over Yallourn. At this point I would be easing back on the go-juice and reducing speed. The slightest sign of turbulence and I reduce further.

How do you prepare for the unexpected though?

Balls to the wall. You get through it quicker that way. :eek::}

And the quicker you get there, the less chance there is for something to break. :ok:

Barbers pole :ok:

Turbulence Penetration Speed, isn't it that speed that the check and training department ask you during your checks, but you never remember nor use later on? :}

Practically it have to be half way between Vne and Stall , greatest buffer. Dont quote this on a line check:ok:

When your eyeballs bounce that much you can not read the instruments!

Or your other balls hurt too much!:} Sorry girls.....keep watchin the dials!:E

Wally,
depends on your weight.
Manual figures for a 210M (1978) are 3800lbs 119KIAS, 3150lbs 108KIAS, 2500lbs 96KIAS.
210N (1984) are 125, 113, and 101 KIAS respecively.:ok:

Do you reckon the chance of the wings clapping over the fuselage are any worse than pipers or beechs? All use cantilever wings. Serious question here folks, any LAMEs know?

Probably no more risk than any other breed.
I do quiet clearly remember looking at the attach points on the C210 when one of the survey company's was forced to change a heap of them out due to working rivets at the attach point to spar joins. I have been scared of those eight little bolts ever since. They are surprisingly small for the job they do. :eek:

hey 'Wiz' that's exactly what I thought when first I saw a few piddly little bolts holding that C210 wing!!!

Seems the funny side of everyone has been tickled with my thread:ok:

'MIHC' I guess that's why they (C210) have a fairly low turb speed because of the somewhat weak attachment design. What puzzles me though about this speed on any A/C is the fact that & this is why I ask the original Q we are all different as in there wouldn't be too many out there that have an exact set of rules as to when to reduce speed due bumps etc. One pilots might always pull the pwr back when it gets bumpy & to another pilot perhaps the very next driver might be happy with bouncing around the sky like a fart in a bottle & not slow up at all, there in lies the quandary. Turbulence penetration speed to me is more an advisory speed because it can't be defined as the same for every pilot when to adopt it.


Wmk2

Not really the way to look at it Wally. Depending on the category the aircraft is designed to take a certain "g" (aerobatic 6 g, normal 3.8 g, or utility 4.4 g). The Va speed is a function of the applicable "g" limit and the stall speed (which naturally changes with weight - fuel burn, payload).

Va = stall speed X square root of "g" limit

So,

Aerobatic category Va = 2.45 X stall speed
Utility category Va = 2.1 X stall speed
Normal category Va = 1.95 X stall speed

What one training organisation had to say referring to a C 172 (3.8 g limit)

In Light Turbulence:

* Use Va

In Moderate Turbulence:

* Cruising speeds should be reduced to 1.6 – 1.7 x Vs (1.65 is ideal) A speed greater than 1.7 x Vs may result in a speed exceeding Va in gusts.
* No flaps when flying a Cessna—remember our load factor limit drops to +3.0g’s.

In Severe Turbulence:

* Slow the aircraft down to 1.5 x Vs. (We need to balance the need to slow down and remain below Va even in gusts while not slowing the aircraft down so much that it may become too difficult to retain control or to where the aircraft stalls with each new gust.)
* Once again, no flaps when flying a Cessna

'BA' all good & well but there is no defined 'trigger' for what constitutes the requirement for reduced speed due turbulence. You mention via a training organisation light, medium & heavy. That's fine I guess you could break it down to 3 cats but what are they to you, to me or others, they might be nothing like what you have added here. Pilots vary & so does a turb speeds application. Unlike a Vlg speed a "no 2 ways about it" speed I find Turb speed "hairy fairy":).

I am just curious as to what others use as a guide for the application of Turb, not a specific formula which can't be applied here due individual perceptions/decisions.
The ref to the C210 having a weak wing att is just my opinion, I used to work on planes & found them to be under-engineered, obviously not so but again just my opinion.
Yr right tho no flaps when flying a Cessna, that much can be done from the 1 hr pilot to the 10000 hr pilot, the rest is guess work believe.



Wmk2

Interesting discussion.
I mean, dang, I don't know, and I've always been curious. There are, of course, descriptions of the symptoms each category of turbulence produces, but still the interpretations are subjective. What rocks some passengers to sleep might cause serious nervousness in others. (Ditto pilots.)

I've always slowed down to around Va any time I thought the ride was getting rough, and always slowed to below the yellow line in any turbulence at all. The possible consequences of not doing so seemed to me a bit serious.

That said, although you say you think light a/c are under-engineered, it would appear they are generally over engineered, which is nice. A lot of quite old lighties are still thumping around, being flown by all from the balls-to-the-wall types, to the overcautious, hardly ever do they fall apart, and some of them must have really been through the mill.
Doesn't matter to me. The sticky-out bits are whats stopping me from heading down at pucker/splat speed, I don't mind easing their load if it gets at all choppy, even if that's conservative. Reasoning: I don't have a gauge of what is/isn't conservative, unless a g meter is fitted, with tables for its use. (Eg: if +3/-1 G's are regularly observed, fly at <xxxkt.etc.) So I would err on the cautious side.

I believe the 210 may have got its reputation because of a few inflight break-ups following spatial disorientation in IMC, because they're so quick to wind up to above Vne, rather than any inherent weakness in the structure. (Not unlike another type that has a nickname used by a poster here.)

Turbulance Penetration Speed is when pax go deadly quiet +10 kts
When feel fingernails slowly penetrate back of neck, reduce speed by 20 kts to restore confidence.
It is amazing how it works opposite ways most of times. When encounter roudy pax, induce turbulance to restore calm.

:ok:

Obviously Va or Vb if specified for your aircraft is the speed you should come back to in moderate to severe turbulence. For me if in light turb I would have no problem sitting 5 or so knots below the yellow arc to allow for gust-induced IAS increases.

I read a very informative article on this subject, relating specifically to the C210. I can't remember the exact figures, but it went something like this:

Va is the speed at which the aircraft will be capable of surviving a 50 fps (3000fpm) vertical gust, theoretically. In actual fact during wind tunnel testing, the C210 was found to be capable of absorbing a vertical gust of (I think it was) 86 fps (5160 fpm).

The article went on to say, and an experienced LAME comfirmed this for me, that aircraft in general, and the C210 in particular, are capable of exceeding Vne by quite a few knots (think like 30+kts). I don't know about you, but for a long time I was under the silly impression that as soon as you got to Vne + 0.0000001kts the wings would suddenly snap off and everything would go to hell REAL quick. The C210 was tested to destruction and it was found that even at Vne, the airframe can absorb a vertical gust of something like 43 fps (2580 fpm) before any structural limits were exceeded.

Further to this of course, structural limits can be survivably exceeded. A normal category aircraft, for example, must be able to maintain +3.8 and -1.52G survivably. In reality of course, you can comfortably exceed these margins in most aircraft...but you are in no-man's land. What I mean to say is that if you were operating in normal category and you inadvertantly stressed the aircraft to +3.9G you probably wouldn't suddenly and spontaneously be a wingless lawn dart.

I am not advocating EVER exceeding the limits specified by the manufacturer in the POH or the Flight Manual, but be aware that these limits are conservative and do not always represent the absolute physical limits of the aircraft or the materials used in its construction.

Finally, I agree with the many people saying that it depends on such variables as the age of the aircraft and its service history. Very important to consider.

interesting post Aerohooligan.

Keep in mind though what you just quoted was for a brand new aircraft, 0 hrs on the clock, 0 damage, nil corrosion.

Most of the aircraft banging around up here are 30 odd yrs old and with more than 10000hrs on them. The machines I am driving at the moment have 14 and 15000 hrs on them.

If it gets to the point where you are starting to go FARK then it's probably time to do something about it and reduce the speed, stop the descent fly level whatever.

I had 1 chief pilot tell me once not to descend above 140kias in this particular 210 because it was full of corrosion and he was concerned the wings were going to come off!:ugh:

At least in the 206 you have the struts for a psychological reassurance!:ok:

Hey Wally if you flew your nemesis you wouldn't have to worry! There is no Va for a PC12!