Re: [Jsbsim-devel] Ch, HM and the P-51D

[Gregory P. <gpi...@so...>]

Agostino

That report was a big help.

Is the result HM in newtons? Using 19deg required deflection at corner to 
pull max AoA, if I convert (newtons to pounds ), it I get 73 pounds of 
required stick force (assuming a 1:1 gear ratio).

With a quick check, the max speed the pilot could pull max AoA is around 
230mph.

Which corresponds to pilots needing two hands on the stick at times.

In use. Flying the P-51 in air combat if you dive on a bandit, exceed 230 
and over shoot, pull into a high yoyo, the high stick force will prevent you 
from pulling the needed tight radius and the bandit will end up on your six.

With our current system, and what all the retail sims use, you can pull max 
AoA at corner. In the scenario above currently the P-51 may have been able 
to pull a tight enough yoyo to stay behind the bandit which it looks to be 
something it should not be able to do.

Does that sound reasonable? Am I heading in the right direction?

gregoryp
AvHistory.org





----- Original Message ----- 
From: "Agostino De Marco" <ago...@un...>
To: "JSBSim development issues" <jsb...@li...>; "Tony 
Peden" <ap...@co...>
Cc: "'JSBSim development issues'" <jsb...@li...>
Sent: Monday, October 02, 2006 1:54 AM
Subject: Re: [Jsbsim-devel] Ch, HM and the P-51D


> Some time ago I wrote the following document:
>
> http://www.dpa.unina.it/demarco/work/UoN_guidelines_force_feedback_1.5.pdf
>
> with some theory about hinge moments.
> Hope it could help.
>
> Agostino
>
>
> Quoting Tony Peden <ap...@co...>:
>
>> Two issues.
>> You should check, but I think you'll find that you are calculating a
>> derivative, call it dCha, so that Cha = dCha * delta_aileron
>>
>> Also, I imagine the Mustang did not have any power assist for the flight
>> controls but you do need to factor in whatever mechanical advantage the
>> system provides.
>>
>>
>>
>>
>> -----Original Message-----
>> From: jsb...@li...
>> [mailto:jsb...@li...] On Behalf Of Gregory
>> Pierson
>> Sent: Sunday, October 01, 2006 1:10 PM
>> To: jsb...@li...
>> Subject: [Jsbsim-devel] Ch, HM and the P-51D
>>
>>
>> Hi Guys!!
>>
>> I'm working on a CFS3 project. I'm trying to determine stick forces for 
>> the
>> P-51D at corner speed (278mph). I have
>>
>> C_h_a = -0.209
>> C_h_d = -0.565
>>
>> I found the HM equation
>>
>> HM = G ( Ch * q * (Sc)
>>
>> G = Gearing
>> Ch = C_h_a + C_h_d
>> q = dynamic pressure
>> S = Total Stab Area
>> c = cord of control
>>
>> So for the Mustang
>>
>> HM = 1 * ( .775 * 198.5 * (13.97sqft * 1.16ft))
>>
>> HM = -2490
>>
>> What I don't see is where the control deflection angle is factored in 
>> (it's
>> only used for efficiency in the C_h_x calc's).
>>
>> I'm at a loss of what to do now. If the pilot can input only 50lbs of 
>> back
>> pressure, is that enough to pull max AoA at Corner Speed? None of my 
>> books
>> go the next step  :-) So I don't know what to do with the -2490.
>> Simplistically, I'm just trying to see how far the pilot can deflect the
>> control vs speed with 50lbs of stick force available.
>>
>> Thanks!!
>>
>> gregoryp
>> AvHistory.org
>>
>>
>> -------------------------------------------------------------------------
>> Take Surveys. Earn Cash. Influence the Future of IT
>> Join SourceForge.net's Techsay panel and you'll get the chance to share 
>> your
>> opinions on IT & business topics through brief surveys -- and earn cash
>> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
>> _______________________________________________
>> Jsbsim-devel mailing list
>> Jsb...@li...
>> https://lists.sourceforge.net/lists/listinfo/jsbsim-devel
>> _______________________________________________
>> The JSBSim Flight Dynamics Model project
>> http://www.JSBSim.org _______________________________________________
>>
>>
>> -------------------------------------------------------------------------
>> Take Surveys. Earn Cash. Influence the Future of IT
>> Join SourceForge.net's Techsay panel and you'll get the chance to share 
>> your
>> opinions on IT & business topics through brief surveys -- and earn cash
>> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
>> _______________________________________________
>> Jsbsim-devel mailing list
>> Jsb...@li...
>> https://lists.sourceforge.net/lists/listinfo/jsbsim-devel
>> _______________________________________________
>> The JSBSim Flight Dynamics Model project
>> http://www.JSBSim.org
>> _______________________________________________
>>
>>
>
>
> ----------------------------------------------------------------
> This message was sent using IMP, the Internet Messaging Program.
>
> -------------------------------------------------------------------------
> Take Surveys. Earn Cash. Influence the Future of IT
> Join SourceForge.net's Techsay panel and you'll get the chance to share 
> your
> opinions on IT & business topics through brief surveys -- and earn cash
> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
> _______________________________________________
> Jsbsim-devel mailing list
> Jsb...@li...
> https://lists.sourceforge.net/lists/listinfo/jsbsim-devel
> _______________________________________________
> The JSBSim Flight Dynamics Model project
> http://www.JSBSim.org
> _______________________________________________