Military Air Transport Aircraft - Maximum Rudder Pedal Force

[InDarknessConcealed]

Afternoon All, I'm trying to find the maximum rudder pedal force required for aircraft such as the C17, C130, Airbus A330, BAe146 and A400M together with the source references. Would these be the aircraft publications or is there legislation that stipulated maximum limits? Can these limits be different if the aircraft is operated in both the civil and military domains e.g.:A330. Any help appreciated.

[John Farley]

The maximum force allowable is of course set by the certificating organisation - see the FAA and EASA airworthiness regs for example.

As to the actual needed to be applied for a given type you will have to decide what speed you are interested in.

[InDarknessConcealed]

Thanks JF. I'm interested in the worst case, whichever part of the envelope that it. I presume it will be slow speed with the critical engine failed.

[BEagle]

Rudder pedal loads in the VC10 were opposed by artificial feel - as were control column loads.

Because the rudder was so powerful, rudder feel was proportional to IAS (up to a limit, whereafter it remained constant), whereas for pitch and roll, it was TAS. Which meant that max rudder feel pressure was generated at much lower speed, as compared to elevator / aileron feel as the feel gradient was steeper.

Even in the event of a go around at VCH, with 2 engines failed on the same side control was easily maintained with rudder pedal deflexion and rudder trim.

[smujsmith]

That's interesting Beags, and would explain a few things about Albert to me. As my only piloting qualifications come from gliding, where rudder usually leads aileron into turns etc, on the few occasions I was treated to a "clutch" of Albert I found the rudder forces were fierce. In fact, I often wondered if after take off the rudder system just locked off, but the force required to visibly notice any motion around the normal axis was huge. Albert like the VC10 had a large rudder so maybe it makes sense it was "limited" at higher velocities. But thanks for making it more understandable.

Smudge :ok:

[sycamore]

IDC, it`s between 150-180 lbs,or was in old money,but dependent whether it was manual/boosted or full hyd. under given conditions.
Don`t think the conditions covered(on a 4 multi) both on critical side pitch-locking at low pitch/power...exciting on a C130(in sim).Select 20 flap( and I think the FE could pop a couple of CBs to prevent flap movement ,but still allow full rudder boost)...Smuj should know..anyway,always got the co to help out on the pedals,as he`d usually had all the pies/curries..

[SwitchMonkey]

For EASA check this link

http://www.easa.europa.eu/agency-measures/docs/agency-decisions/2013/2013-010-R/Annex%20to%20ED%20Decision%202013-010-R.pdf

Search for rudder force and you will find mention of both 150 and 180 lbf and the respective circumstances.

Hope that helps.

[Arm out the window]

The maximum force allowable is of course set by the certificating organisation

Almost completely irrelevant query here, but why do they always say 'certificating' and 'certificated' in reference to aircraft design rather than 'certifying' and 'certified'? Is this a Yankeeism, or do I just not know my words proper like?

[Tester07]

I think there may be different answers to this question depending on precisely what you mean.

What most people think of is the maximum allowed for certain handling requirements, i.e. the minimum control speeds when the maximum for civil and military requirements is 150lbf.

The C 130 was originally tested to mil specs which specified 180lbf, which gave Lockheed some concern when testing the C 130J to civil limits which specified 150lbf. I think that civil and military specs have been aligned at 150lbf for some time now.

The Herc in particular is rudder force limiting at minimum control speeds, which means that at this speed you will in fact experience 150 lb rudder force, in the case of the 130 J for some time (about 80 to 130 KIAS) as the aircraft accelerates and the ATCS system automatically feeds back in the power of the opposite outboard engine.

Most aircraft will have considerably less force than this at minimum control speeds, which will be determined by full rudder pedal application.

If you look at the loads section of Part 25 you will see that flight control systems must be stressed for a maximum force of 300lbf.

There are also maximum short term and long term forces which a pilot can be expected to withstand in any possible failure case. I cant remember what these are off the top of my head but Im sure someone on here will be able to find them.

Cheers,