737NG control forces

[kikigey89]

Hi all,

I am participating in a 737NG cockpit project. Currently we are working on a better yoke and rudder system. For best feeling we would like to set almost the same control forces like in a real 737NG.

Does anybody know where we can find some information about the control forces which act on the yokes and the rudders? How do these forces change while trimming the aircraft?

Hope you have some ideas :)

Chris

[fordgt40]

Chris

Try these links - there is a lot of info and a downloadable programme for control loading on the first link

http://buggies.builtforfun.co.uk/Sim/force-feedback-yoke-1.php
http://www.simprojects.nl/diy_force_feedback_interfacing.htm

David

[kikigey89]

Hi,

sorry for my late response, I was busy with the flightsim conference in Paderborn, Germany.

I already know these links but what is missing is a measurement on a real 737NG. I need some diagrams with yoke deflection and force.
Any idea in which documents of Boeing this can be found?

[fordgt40]

Chris

Sorry, but I am not aware of any site which can provide actual force figures for various aerodynamic configurations. Presumably it would be infinitely variable being dependent on speed, trim, weight, CofG AoA, flaps and gear etc. Do you have a friendly 737 pilot who can help :)

David

[kikigey89]

I am not sure if the control forces change with another configuration. Also in a 737 the control column is not directly connected to the flight control surfaces. In between are hydraulic actuators and as far as I am informed, there is no feedback from these actuators.
I got some raw data from an airline technician but I want to doublecheck this information.

Unfortunately pilots have a more suggestive view of the aircraft and if I ask some pilots (I know some) everyone tells another story. So it makes no sense for me to work with them. I need objective values from manuals or something like that.

[fordgt40]

Chris

There is indeed force feedback on early 737`s, dependent on airspeed and trim. Link attached, relevant section is towards the bottom of the first page.

http://www.737flightsim.com/737center.html

Also, I have heard from a 737 pilot that at take-off you should be able to pull back the yoke with just 2 fingers

David

[DarrenBe]

Information on actual control forces is next to impossible to obtain, unless you have access to an aircraft and it is instrumented accordingly to record the data you seek.

Your best option is to review the certification specifications for the B737NG and look at what the maximum allowable control forces are for pitch, roll and yaw. EASA Part CS25 would be a place to start. http://easa.europa.eu/agency-measures/docs/certification-specifications/CS-25%20Amendment%209.pdf

It might not be perfect but should be accurate enough for simulation purposes. This was the same tip given to me by someone who designs control loading systems for a living.

[kikigey89]

Many thanks for your answers! The http://www.737flightsim.com link helped me a lot!
I already took a look in the CS25 but could not find any clue for the control forces.

Chris

[DarrenBe]

CS 25.143 (page 1-B-13 & 1-B-14) contains the information on acceptable control forces. This includes a table for pitch, roll and yaw. You should also review the AMC (Acceptable Means of Compliance) section AMC 25.143 (from pages 2-B-47 through to 2-B-50), which contains additional information on acceptable control forces.

There is plenty more information within CS25. Do a search for the term 'control force' within the document.

[will1911]

I don't think you'll be able to find the actual 737 control forces anywhere. Boeing sells the data to CAE/Thales/etc. for a lot of money. It probably won't show up on the internet.

I also think the 737 control forces are quite hard to simulate without the data. The position of the engines create huge pitch up/pitch down movents when increasing/decreasing thrust. For example, if you increase thrust for a G/A, you hardly have to pitch up. If you don't have the data, you'll never be able to simulate it realistically, especially if you've never flown the actual plane.