Physical strength of legs for rudder.
 

On the medical forum, I was talking about strength of knees needed in modern transport aircraft, I guessed at 100-150lbs. Is there a stated figure for the physical power needed in failure configurations?


http://www.pprune.org/forums/showthr...=1#post2755671

Current design standard (FAR 25.149(d)) is 150lb. The value has varied over the years according to the particular certification but, as best as I can recall, the only other figure of note was 180lb.

Gets interesting on some of the older birds after a while when the leg starts shaking uncontrollably ...

Absolutely - can't vouch for the Meteor, but certainly the dear old Canberra (other than the PR9 with its powered rudder) was a right old "knee trembler" on one donk and you had to lock your leg straight on full rudder during an assy overshoot. If you didn't, it provided much amusement to the QFI next to you in the T4 as your leg gave a good imitation of someone with the DTs.

Thanks for that. Not a bad guesstimate after all.

My retirement job was on ATRs...okay in flight, but after loooong taxies rather wearing.

Light Twins.
 

Is that the same for light twins??

The early long body 707's (with JT-4A engines) took a hell of a push on the rudder with an outboard failure at rotation, so much so that many guys had to raise their backside right off the cushion and prop themselves against the seat back, to keep the aeroplane straight.
Interesting times indeed.:ok:

The old DC3 (don't laugh) could be a bugger on one engine at heavy weights. I recall using 2 feet on one pedal (trim was wound over to the stop) while single-engine on a hot day somewhere in 'high' Africa! Betty Swollocks!

long time since I've had a fly in the Dak but, if I recall, it was 180lb ?

For lighties, the current rule is here and is 150lb.

The British ARB (CAA now) insisted on a fully boosted rudder and an increase in tab authority before BOAC could put them on the British register, for that very reason.
In fact I cant remember now but I think there was a difference in the -300 and -400 as well:confused:

180 lbs? John, I've no idea! I just remember it got horrible as the speed slipped back towards Vmca.

John,

Do you happen to know how many lbs for a Canberra T4 at Crit Speed? It felt like about 300.

Regards,

Rod

From an antropometric Handbook :

Pressing Pedal .... age 31 - 50; A pedal 400mm length and 30mm wide, placed inside a 55mm wide space to restrict the amount of the foot that can be placed onto the pedal.
Sex Mean (Nm) S.D (Nm) Range (Nm)
Male 329,183 129,99 173,00 - 579.70
Female 237,99 106,80 121,50 - 435,60

So Rambo can push about 1450 N or about 300 lb
I have no idea, for how long this force can be maintained.

.. fond memories of watching Canberras do their thing but no idea what the leg load would be ...

Ha you're all pansies! Bloody Martinet required two of us on the pedals. Specially with P/o Prune popping away at the drogue.

The rudder force required for the DC3 was/is indeed 180 Lb, which, at the time that I flew it, exceeded my body weight.:eek:

Maybe I should go back and do it again, now that my body weight is somewhat in excess of 180 Lb.:E

As John_T indicates, the requirement now is for a much more "sissy" 150 Lb.......

Regards,

Old Smokey

.. I incline to a view that, at our mature stage of life, the body is in harmony with architectural splendour rather than the whippet gristle and muscle of our misspent youth ...

>>The British ARB (CAA now) insisted on a fully boosted rudder and an increase in tab authority before BOAC could put them on the British register, for that very reason.
In fact I cant remember now but I think there was a difference in the -300 and -400 as well<<

Yes, and as I recall, this was at the insistance of DP Davies.
Operated the -300 (JT4A) extensively and the -400 less so, and I expect they were about the same....but you could be right, gas path.

From the AA 587 crash various rudder forces were published. I believe the highest rudder force was about 80 lbs(?). I think all the newer Boeing products use that.

Typically the first 22-25 lbs of rudder push does absolutely nothing. It's designed that way to avoid having accidental inputs when a lesser force is applied.

(A300)Below 165 kts(?) full rudder travel force was 66 lbs. At the accident speed (250 kts and still accelerating) full rudder force was 33 lbs, or 11 lbs above 'breakout' force.

Rudder travel below 165 kts was 3.8 inches. At accident speed was 1.3(?) inches.

Older jets (737/DC-9s/S-80's/727/707, etc) had this type of rudder design.

Newer Boeing products (747/757/767/777) keep a constant force and rudder travel requirement. IE 4 inches and 80 (?) lbs, at any speed gives you 100% of available rudder travel. But at higher speeds the rudder travel is restricted to avoid over controlling, and/or damaging the a/c.

I'm not aware of the medical standards but a friend returning from SEVERE pelvis/leg injuries (shattered from waist down...) had to fly a complete single engine pattern without using any rudder trim. First attempt wasn't successful. A month later he was strong enough to pass.

He he.....


Well, I never expected a response like this...though come to think of it, one of the few times that I have considered shouting MAYDAY, was on the ground in a DC3. I've posted on this before, but it was very serious. AMS and fast vehicular traffic on the right...down an embankment.

It was more to do with fading brakes, but my legs were giving out. The more stb engin, the faster I went. ANY reduction in power swung me towards the motorway. Taking off on the taxiway seemed the only option for a few horrible moments. But then the winds changed.

There was a captain at SEN in the early 60s. He would growl, smoke and drink...and occasionally speak. ASSISTANCE ON THE RUDDERS was one of the things he said to me. Young folk have no idea....CRM? God, that was ducking the captain's fist!

No Mate!!!

... CRM? God, that was ducking the captain's fist!

I learnt to fly with a small group of chaps some years ago ... the instructor (ex Airline and now long dead) had a view that a fundamental instructional technique involved a rolled up newspaper .. the student was permitted one mistake in any given area of training, a further briefing, and then a clout around the ears with the said rolled up newspaper if the mistake were to be repeated.

Perhaps not PC in these modern days but definitely focussed the student's attention on the task at hand .... with the exception of one student (who took around 10 hours - obviously a tender headed youngster) we all went solo in 4-6 hours so perhaps there may have been some instructional validity in the technique ?