[simpits-tech] RE: [simpits-tech]F-16 Side-Stick-Base

[Craig Rochester]

Marv,

Look here on page 5 for non-linear roll description.
http://www.dfrc.nasa.gov/DTRS/1996/PDF/H-2031.pdf  I Can't remember seeing anything about the pitch
curve.

I've done a lot of web searching and not found too much.

Thanks,

Craig R.

-----Original Message-----
From: simpits-tech-admin@simpits.org
[mailto:simpits-tech-admin@simpits.org]On Behalf Of Marv De Beque
Sent: Thursday, August 07, 2003 5:14 PM
To: simpits-tech@simpits.org
Subject: Re: [simpits-tech] RE: [simpits-tech]F-16 Side-Stick-Base


My friend who flew them said something like 3 G's for ever 5 lbs of force,
but I think that seems wrong since you can max out at +9 G's (+9 G is the
limit that the Falcon's FCS will let you have, it's electronically governed)
with 25 lbs. of force on the grip..

If the curve is really linear, then that is 9/5 or 1.8 G's per 5 lbs. of
force.

If it is the same for pitch, then 19 lbs. would yield -6.84 G's in pith
down.

I'll bet the the force curve versus G's pulled is not linear.

Another thing, the fly-by-wire system has been around for some time and I
would think that the USAF has dinked around with the maximum forces required
for full G, force curves, as well as grip deflection.  I would think you
could look back historically and see that they have been fine tuning those
numbers as the aircraft design matures.

Marv


On 8/7/03 3:35 PM, "Craig Rochester" <johncraigroch@msn.com> wrote:

> Marv,
>
> Thank you very much.  That helps a lot.  Three real sticks say it all for me;
> 19 lbs. it is. :)  I
> didn't know the flight control system's control variable was G's... that's
> cool.  Makes sense when
> the pilot's G-tolerance is the limiting factor in hard maneuvers.
>
> Thanks again for your help,
>
> Craig R.
>
> -----Original Message-----
> From: simpits-tech-admin@simpits.org
> [mailto:simpits-tech-admin@simpits.org]On Behalf Of Marv De Beque
> Sent: Thursday, August 07, 2003 12:31 PM
> To: simpits-tech@simpits.org
> Subject: Re: [simpits-tech] RE: [simpits-tech]F-16 Side-Stick-Base
>
>
> I find the reverse is true when actually seated in a cockpit with everything
> set in the correct orientation (seat, stick position and grip orientation,
> rudders, etc.).
>
> A friend of mine is/was an F-16 driver and he stated that the position that
> most pilots adopt when flying the Falcon is with their head and upper torso
> slightly erect as opposed to laying back fully in the seat.
>
> The correct force for pitch down is 19 lbs. for full deflection.
>
> I think one of the documents you gave me, Craig, also backs this up with an
> explanation.
>
> I have three real side sticks that also seem to back up that number, but
> since these are removed from service, I can't be certain that their
> calibration is still good.
>
> Additionally, the electronic flight control system of the Falcon is set so
> as to produce a set amount of G force that is proportional to the amount of
> force applied to the grip unlike conventional aircraft that yield a set
> amount of elevator deflection for a set amount of stick movement.  If that
> force is the same for both directions in pitch, then it makes sense that the
> forward force required would achieve maximum G's in the negative direction
> is less than pulling back would.
>
> Marv
>
>
> On 8/7/03 9:30 AM, "Rochester, Craig" <CRochester@biopure.com> wrote:
>
>>
>> Thanks ben,
>>
>> I agree with you for 2 reasons:
>>
>> 1.    After "flying" my test rig, I find that I have a better mechanical
>> advantage for pushing the stick forward.  Because shoulder is supported by
>> seat back.  I didn't expect this.
>> 2.    The pitch-down axis was purposely limited in travel to reduce over
>> controlling.  Why would you make it stiffer but lower the max force?
>>
>> Anyone see it differently?
>>
>> Thanks,
>>
>> Craig R.
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