American Airlines 737 Cockpit Experience...

[sagrada737]

Hi Guys,

I shared this with Sam and Steve, but thought it might be of interest posting here on the forum.

I had a great time at CBWF in Sarasota, FL.  It was nice to meet and talk with everyone and participate in flying the various routes for WF.  Thanks again Sam for being such a gracious host.  Your Sim is truly awesome!  Also, thanks again to Bob and Trevor for all their hard work keeping things rolling at CBWF.  I'm looking forward to CBWF 2014.

When I left Sam's for my flight out of Tampa, I was hoping to get a peak at a real 737 cockpit.  It turned out that my flight from Tampa was on an American Airlines 737.  As I was boarding the aircraft from the jetway, I asked the flight attendant if I could ask the Captain a question.  She said with a smile, "Of course." and moved aside to let me pass through to the cockpit.

When I entered the cockpit area, the Captain and First Officer were in their seats.  They looked up with a bit of a surprise.  I told them I was building a full-scale 737-800 simulator.  Immediately their eyes lit up and a big smile came over their faces as they said, "That's really cool." 

I indicated that I wanted to get a feel for the "stick forces" of the Yoke and Column.  To my surprise, the First Officer immediately jumped out of his seat and said, "Have a seat."  I wasted no time putting my bags on the jump seat and I moved into the FO seat and rolled the seat into position.  I think they were a bit surprised that I knew how to adjust the seat - same seats as Sam's sim.

I took hold of the Yoke and moved it through its limits, feeling the Cold & Dark stick forces - hydraulics OFF.  I told the Captain that this was a lot more stiff than I expected.  He immediately said, "Here... Let's turn ON the hydraulics."  Immediately the Yoke and Column came "alive" and as I moved the controls back and forth, I could get a fairly good idea of the forces and dampening of the controls.  The ground crew probably thought the flight crew had gone nuts with all the control surface movements 

My only benchmark was Sam's simulator.  But what I found was that both the Yoke and Column stick forces were about twice that of Sam's setup.  Also, there was considerable dampening in both of these systems.  When the Yoke and Column were moved to their extents and released, they moved slowly back to center, without oscillation.  It required "intentional" force to move either the Yoke or Column, yielding a very solid feeling to the Yoke and Column movements.

Having had this neat experience was one of the highlights of my trip to CBWF.  I certainly have a better idea of the control forces for the Yoke and Column.  Who says you can't get into the cockpit of a 737 these days 

Thanks again all for the CBWF event, and thanks to the CA and FO at AA for sharing their world in the 737 cockpit.

Mike

[MLeavy737]

Just remember those are the control forces at the gate once in air those forces are very different during the phases of flight! However at least you got a nice idea how the damping is.

Mike L

[sagrada737]

That's a good point Mike.   I suspected that they might be much more sensitive (less heavy) in flight.  Could you comment on the difference with hydraulics ON between operation on the ground vs. in-flight?  Thanks.

Mike

[ETomlin]

Mike S- Thanks for sharing this with us. I too am eagerly waiting for Mike Levy's answer because I was truly impressed with how heavy the controls were on Sam's sim and figured they were really close to reality.

[tennyson]

I, too, was interested in this question a while back.
I asked my friend, who is a head engineer for a major airline and he shared some data with me.

I don't quite know where I've put it, but to my recollection, the stick forces were 32 pounds of force fore and aft to bring the 737-800 stick to the full forward and rear position. I assume that would be with hydraulics on.

I used a small gas strut to my linked control columns to give the hydraulic feel and a spring tension to imitate the 32 pounds of force required.
It feels good to me, but then again, I've never been lucky enough to feel the real stick forces like you, Mike, you lucky man.


Frank Cooper 

[sagrada737]

Interesting comments Frank...   I found an comprehensive description of 737 Flight Controls that sheds some light on so-called "stick forces" of the 737 Control Wheel (Yoke) and Column.

For our Sims, it seems logical that our world is one of compromise in obtaining the "feel" of the real 737-800 aircraft.  This usually means some kind of spring and/or dampening centering mechanism that meets most of the requirements and provides "reasonable feel" when operating the flight controls - this of course is all over the map and quite subjective from one Sim Project to another.

From what I gather at this point, dampening is needed to meet this requirement.  Further, it seems that the real 737 definitely does not move so freely so as to "oscillate" when the controls are released from their full extent of movement.

From what I understand thus far, it seems more appropriate that the flight controls have "progressive dampening" that is based on aircraft speed, without compromising responsive control input movements.  Obtaining this kind of dampening may be beyond the simplicity desired by most Simmers for their home cockpit.  In this regard, some kind of linear dampening may be the closest thing we can incorporate without excessive mechanical complexity or cost.

In the real 737, it appears that a computer controls the hydraulics/cam system to "modify" the control forces depending on flight mode, including handling problems like jammed controls - something beyond most hobby sim requirements.

For our Sim control systems, it is clear that we need both the CA and FO controls to be mechanically sync'd - usually with tie-rods or similar mechanical approach.  Further, we need the controls, when relaxed/released to move to their physical "centered position" that reflects the calibrated neutral position as set within FSUIPC - a primary requirement.  How to achieve this while incorporate the best "feel" when moving the flight controls seems to be the major challenge in designing and building sim flight controls.

All this is of interest to me, because I am new to building a 737 sim, and the fact that I'm just beginning to start work on integrating my real 737 Yoke/Columns into my flight deck.  After having the chance to get my hands on real 737 flight control forces (albeit on the ground), I realize that this is more complicated than I originally thought. 

But since I am starting from scratch, I have the opportunity at this point to take a shot at coming up with a design that better emulates the 737 flight control forces for my Sim Project.  I could take the easy route and incorporate the typical spring loaded system, but I think I would be missing the opportunity to put more thought into this important part of the Sim system environment.

Anyway, none of this is new or unique to our Sim requirements, so if others have constructive suggestions, they would be most appreciated.  Here is the link mentioned above:

http://www.737ng.co.uk/B_NG-Flight_Controls.pdf

Mike

[Jetcos]

I think we are approaching "Control Loading" if you want all the feel from all aspects of the forces used on the yokes. I know somebody headed in that direction and would love to try his yokes when he is done. If we are lucky he will chime in with his set up ideas.

http://bffsimulation.com/force-feedback-column-1.php  is one source.

[MLeavy737]

Mike S- Thanks for sharing this with us. I too am eagerly waiting for Mike Levy's answer because I was truly impressed with how heavy the controls were on Sam's sim and figured they were really close to reality.

Sorry for the delay..  Its obviously somewhat tough to explain how the forces really feel however what you felt Mike is the damping forces and thats a good start cause that remains in all phases.  I guess i would say takeoff phase is pretty close to the gate feel except you don't really feel the center detent once your flying as you do sitting at the gate. In cruise the feel is the heaviest which when you think about it you don't want light feel up there at high speed. Approach phase is like the takeoff phase and flaps 30 gets pretty light and flaps 40 is very light and responsive! 

Not sure if any of that helps lol. The way i had my sim controls was pretty neutral i guess. In between i would say. Too light and then you also have centering problems, especially with damping involved. Too heavy is obviously just too much work!

O yeah did i mention i sold my sim?? lol

Mike L

[jackpilot]

Mike (Sagrada)
If you really want to go at it, here is a wealth of info.
Check Pages 1 and 2
http://www.737flightsim.com/737center.html
BTW David's site is a tech bible, check other topics.
Cheers
Jack

[sagrada737]

Interestng info guys...   The linkage incorporating the linear actuator/cam system seems to have merit, in order  to emulate the "feel computer" for variation in control forces as a function of speed - seems like a viable approach.  Lots to consider before I settle on a final design for my control setup.

Thanks for the feedback.

Mike

[jackpilot]

If I remember well, Axel posted on the real 73 system.
Jack

[Ridgenj]

Many thanks for sharing! My wheel controls are being manufactured in Europe and depending on the final product, I might take the representation for the US.
These discussions here are very educative.
BTW, we will produce first 20 units and once gone, voila!
No orders without an available product.

Cheers
Luis

[Sean]

Thanks for the [force] feedback.

Sorry, couldn't resist!