Maneuver Speed

[djpacro]

The definition of Maneuver Speed is:

 

The design maneuvering speed (VA) is the speed below which you can move a single flight control, one time, to its full deflection, for one axis of airplane rotation only (pitch, roll or yaw), in smooth air, without risk of damage to the airplane.

..... more.

 

 

[David Isaac]

Must be the topic of the day girls and boys.

 

 

[djpacro]

Another excellent set of notes at http://www.flightlab.net/Flightlab.net/Download_Course_Notes_files/8_Maneuvering.pdf - rolling G too.

 

 

[djpacro]

... djpacro must have missed this discussion and has kindly also started a thread on the Va subject with some very good input, his post is also embedded here -

Actually, just for info, I started this thread a couple of days before yours but carry on over there, I don't miss that discussion.

[Head in the clouds]

Actually, just for info, I started this thread a couple of days before yours but carry on over there, I don't miss that discussion.

I now see that you did, my apologies, I don't know why I didn't notice this thread earlier, I check all new threads and posts ...

 

Maybe a moderator could combine them?

 

 

[SDQDI]

Lol HITC it sounds like DJ is happy for the other thread to stay separate

 

 

[djpacro]

It seems that the word is spreading ...... http://www.avweb.com/news/features/The-Risks-of-Maneuvering-Speed-Myths222680-1.html

 

 

[poteroo]

The definition of Maneuver Speed is:..... more.

Thanks for posting these references. Puts a new light on the subject.

 

 

 

When I learned in the 60's, there wasn't much understanding of Va, Vb - other than that they were numbers you should keep in mind when navigating around big Cb, or in a developed standing wave over mountains. Certainly didn't appreciate the very wide window of Va that exists in good load carrying aircraft. Even the old C172 has a Va 'range' of approx. 89 to 103 kts. Because RAAus types don't have quite the same load carrying ability - their Va range is closer.

 

 

 

I have been amazed that there is such a poor understanding of Va. Many BFR candidates state that they can fly with impunity at normal cruise ' as long as they are not in the yellow arc'. Now that's waaaay above Va in most aircraft - often by 20-30 kts.

 

 

 

These new presentations pose questions for recovery techniques from a developing spiral. Reducing power will be the 1st step - as currently taught. Once up near Va - it's definitely unsafe to try to roll out of the turn plus ease out of the dive - using both aileron and elevator together. And, it would require that only sufficient rudder is used to balance the aileron input. So - for me, more emphasis now on sequential control input when speed is increasing near or over Va.

 

 

 

Over the years, the emphasis has been on not exceeding Va when in moderate turbulence. Most pilots will reduce to at or just under Va if things get bouncy - but even this now appears to have been too high. The advice given to use 1.6 - 1.7 x Vs seems prudent. In really rough air, I've used an IAS half-way between the calculated Va, (for the aircraft current weight), and Vs. If your hypothetical aircraft has a Va of 100 and Vs of 50, then 75 is a safe number to hold because you are splitting the difference between stalling and airframe damage. If the aircraft was near empty, Va might be 90, but the Vs might be 45 - so the mid point is 67.5

 

 

 

It's probably time for instructors to carefully check through their aircrafts' POH and do some calculations to determine Va at different gross weights - maybe even placard them near the ASI?

 

happy days,

 

 

[facthunter]

Some people are not comfortable near Vs, but you are easier on the airframe loads. I have experienced over 50 k variation in airspeed with out power or attitude change. That puts you right outside the range(s) in most aircraft. I feel better with a bit of power on once the speed is reduced. You will need power if you lose airspeed quickly.

 

Be gentle on the controls especially in pulling the stick back. You may need to push it forward more forcefully. Maintain attitude rather than chase airspeed. A lot of aileron can twist the wing . Nev

 

 

[ben87r]

Be gentle on the controls especially in pulling the stick back. You may need to push it forward more forcefully. Maintain attitude rather than chase airspeed. A lot of aileron can twist the wing . Nev

I've always been tought to maintain IAS in TB nev and not to chase ALT, that IAS may be >VNO or VA/VB if required, can you eloborate? I may have misunderstood the statement. Cheers

 

 

[eightyknots]

...

 

 

 

Over the years, the emphasis has been on not exceeding Va when in moderate turbulence. Most pilots will reduce to at or just under Va if things get bouncy - but even this now appears to have been too high. The advice given to use 1.6 - 1.7 x Vs seems prudent. In really rough air, I've used an IAS half-way between the calculated Va, (for the aircraft current weight), and Vs. If your hypothetical aircraft has a Va of 100 and Vs of 50, then 75 is a safe number to hold because you are splitting the difference between stalling and airframe damage. If the aircraft was near empty, Va might be 90, but the Vs might be 45 - so the mid point is 67.5

 

 

 

It's probably time for instructors to carefully check through their aircrafts' POH and do some calculations to determine Va at different gross weights - maybe even placard them near the ASI?

 

...

Very informative, poteroo. Thanks!

 

 

[facthunter]

Ben, Chasing airspeed means just that. Maintain an attitude and power setting that has the fluctuating airspeed in the RANGE you want it to be. If you try to pin it too precisely you may overcontrol which is the point I wish to emphasise. Same as control inputs with attitude, You don't try to control it too precisely or you may overload the plane or have one control overriding another (rudder aileron relationship). Nothing I say should preclude you nosing forward positively or backwards more cautiously. or changing power significantly in an up or downdraft that persists. Aiming for an APPROPRIATE attitude is your prime method of maintaining control in turbulence. You still scan all the other instruments to ensue the attitude you have selected is the correct one for the speed (range) you choose to avoid stall at one end and overstressing the aircraft at the other.. If this confuses you talk to your instructor . It MAY conflict with what you have been taught, but I hope not too much (if it does). Nev

 

 

[dutchroll]

I've met a couple of aerobatic pilots (not here - in the USA) who reckon that you can still apply max control deflection above Va. However I must qualify that by stating that those particular individuals are, shall we say, "rather impressed with themselves".

 

I personally plan on not testing the ultimate structural load capability of my aircraft, so I'm pretty careful about piling on the G above Va.

 

 

[facthunter]

They used to say "there are OLD pilots and BOLD pilots but no OLD BOLD pilots".. Nev

 

 

[djpacro]

I've met a couple of aerobatic pilots (not here - in the USA) who reckon that you can still apply max control deflection above Va.

They exist here too. The misinformation is actually quite widespread, not helped by CASA per their CAAP 155 on aerobatics: it states that Va is the maximum speed for full elevator deflection but provides nil information on the other controls.Related question - straight and level upright at Va can we apply sudden full forward stick (elevator)?

(CAAP 155 states that we can.)

 

However I must qualify that by stating that those particular individuals are, shall we say, "rather impressed with themselves".

And they seem very surprised when they fail the knowledge test.

[eightyknots]

I've met a couple of aerobatic pilots (not here - in the USA) who reckon that you can still apply max control deflection above Va. However I must qualify that by stating that those particular individuals are, shall we say, "rather impressed with themselves".

 

And they seem very surprised when they fail the knowledge test.

And they will be even more surprised when they tumble earthwards after their "airplane" (remember they are US pilots) suffers a structural failure due to their irresponsible actions.

 

 

[djpacro]

... after their "airplane" (remember they are US pilots) suffers a structural failure due to their irresponsible actions.

Mine was built in the USA and the manuals states that it is an airplane so that is what it is (CASA regs require me to do what the Flight Manual states). And, just to clarify, I was only referring to Australian pilots. There are plenty of examples of failures of secondary structure.Date, place and names in this story de-identified: over dinner with a bottle of red (not essential to discussion of aerobatics but it helps) talking about certain aggressive manoeuvres in a particular airplane. The limits that I applied were very much less than my colleague was using. The very next morning observed a buckle in the wing and an apparent broken rib.

 

 

[facthunter]

You "observed" that but what can't you see?. These D heads overstress a plane that others subsequently fly. Utterly irresponsible.... Even flying below the "G" limits can result in excess load if you hit a gust at an inconvenient time Nev

 

 

[jakej]

Dave

 

It may be a good time for you to enlighten us about rolling G - would you ?

 

Jake J

 

 

[dutchroll]

Related question - straight and level upright at Va can we apply sudden full forward stick (elevator)?

Lol, that depends on who you talk to!

But no, Va is the design manoeuvre speed for a positive load factor, not a negative one. You throw in full down elevator at Va and you're guaranteed (well in most aircraft I think, and certainly in mine!) to overstress in negative G.

 

 

[djpacro]

I agree, dutchroll, but that would mean that CASA is incorrect with that text in the CAAP per my post #15. Fortunately, we don't have negative snap rolls from upright flight in contests these days (they were not pleasant in my opinion) but we still need to consider full forward stick from zero G (on a vertical line) or at -1 G.

 

DaveIt may be a good time for you to enlighten us about rolling G - would you ?

Jake J

My notes will appear in the aerobatic club's e-magazine starting in January - register at their website or FB page to get it free. As it is only quarterly it will probably be late next year before I get on to rolling G.In the meantime, CAAP 155 has a bit of info on this subject and there is some good info here: http://www.flightlab.net/Flightlab.net/Download_Course_Notes_files/8_Maneuvering.pdf

 

 

[pmccarthy]

I haven't heard of a rolling g but I have heard of a flying f.

 

 

[jakej]

I haven't heard of a rolling g but I have heard of a flying f.

you must have 'sticky' keyboard flying f = old fart

Jake J

 

 

[poteroo]

Lol, that depends on who you talk to!But no, Va is the design manoeuvre speed for a positive load factor, not a negative one. You throw in full down elevator at Va and you're guaranteed (well in most aircraft I think, and certainly in mine!) to overstress in negative G.

Agree. The Va for negative is actually your Vs x sq rt of -ve LF. The positive Va is, by example, ( if Vs = 50, so Va = 50 x 1.95 = 98). So in most +3.8 x -1.9 LF aircraft the Va would be considerably lower for negative LF, eg 50 x 1.40 = 70. How does this translate to an aerobatic aircraft - probably is understandable because of their higher LF's? Then add in the rolling forces..... doesn't bear thinking about! happy days,

 

 

[dutchroll]

The bottom line for an aerobatic aircraft is........watch your G meter. If you are applying symmetrical, non-rolling G loading and you stay within your G limits, you're good to go at whatever speed.