SurClaro Flight Simulator Resources

Posted: Thu Jan 19, 2006 12:08 pm Post subject: Trimming problem

I do not know if it is OK to ad to a thread last added to in 2004 so since I have been facing the same problem I have started this new thread. If any of the moderators find it improper please move it elsewhere.

The problem is trimming my a/c. I am always almost there but never quite. You see I get to a point where my a/c is just climbin very very slowly. I hit the trim down button just a teeny little once, and I correct too much. The a/c is now descending, again very very slowly. OK if I trim up with just one short jab at the button the a/c is now back to climbing slowly. I tried using the joystick buttons for short single strokes, tried with the mouse on the panel trim wheel, and always I correct too much. I have FS9.1 installed on an XP Home system.

I searched for this topic in these forums and saw a post by rhythmosaur in

http://forums.surclaro.com/sutra14550.html&highlight=trim#14550

where it was mentioned that as a last resort you can edit the aircraft.cfg file. Any ideas how? And is there no other solution?

Posted: Thu Jan 19, 2006 1:55 pm Post subject:

I don't know if it is the correct way... but i'll usually fine tune the trim with power settings... increase/decrease the throttle just a tad

Posted: Thu Jan 19, 2006 4:08 pm Post subject:

Trim is a problem... Some planes trim easy and many trim too fast...

I don't tinker with the aircraft config files... Way too much trouble... If a plane flies poorly. I dump it and find one that does....

The way I solved the trim problem was to purchase the Abacus panel designer and add digital trim meters to the panels of my favorite planes.... Once you use a trim meter you can understand why trimming without a meter is so hard.... I found a new digital trim meter that reads in decimal increments, this way you can really fine tune the trim.....

It is very interesting to watch the trim meter during an ILS landing.... Plus you can check the trim meter before take off. After an ILs landing the trims can be extreme and cause a nasty take off...

Most aircraft have old outdated gauges plus many are pre FS9 and don't work properly that cause weird problems with the aircraft... This happens quite often... I replace the buggy gauges with new modern ones, or hunt around and find gauges that will work properly...

It is a good idea to avoid FS2000 planes that have been refrubished for FS9. They usually have bad gauges or switches... I had a refurb turbo prop where the generator switches would turn themselves off randomly. I solved the problem by ripping them out and replacing them with switches from another plane that worked ok....

I fly Alaska mostly. I add my "bush" panel to each plane... This includes a digital trim, digital radar altimeter, a digital/analog altimeter, the King Beech Bendix HSI and ASI gauges, King Beech Bendix radio set, digital OAT(air temp), and a digital clock ( for the long haul planes I add the time shift clock)
The Bendix Beech HSI and ASI gauges are the best for ILS and GPS/DME landings, which is important in Alaskan real time weather. Lots of foggy/snowy landings...
You should see my Super Tundra Cub panel.. It looks like a 727 panel, but very handy for flying between mountan peaks in a white out...

Tj

Posted: Thu Jan 19, 2006 5:29 pm Post subject: Trim problems in a/c

Try going into the FUEL / PAYLOAD edit on the main screen in sim or at beginning of setup. Look at the DEFAULT fuel load the creator of a/c has balanced out for the Center OF Gravity. CG IS A MOST CRITICAL PART OF FLIGHT PLANNING. Without configuring your planes M.A.C.: Mean Aerodynamic Chord %, please do research as this is aerodynamics II, the plane will NOT be in BALANCE. It will fall out of the sky if tail heavy, or will nose in, if front heavy. PLUS any direction the CG is out, the plane will tilt towards that direction if the CG is out of whack.

In the Air Force, on KC-135A's & B-52H models, BOEING has a spot to check the % of MAC, as it is formally called in aerodynamics. It is in the LEFT WHEEL WELL on the center body rib running the length of the keel of the plane. Just a spot to hang a plumb bob over a chart 8 feet below the plumb. It will float towards the TRUE CG. The tablet is mounted stationary on that rib on a small VERY STRONG (to prevent distortion) platform of metal: AL-7075-T651 aircraft/aerospace grade AL, near the inside of the wheel well bay. This tablet has the % of MAC numbers on it for any given plumb position that occurs when measured.

It is good to know because you can shift the CG position by transferring fuel from one tank to another. Also, maintenance will provide a few ways to shift this percentile. 37% is what the MAC is for a Tanker and lower for a BUFF as they fly taking off with tail up first, naturally nose heavy due to potential bomb loads. Simply try to move the load of fuel around to the position that will counteract the force of the A/C pulling up or down, left or right.

It will only work if the fuel and trim problem are proportional. If the trim goes out again after an hour of flight.: the bird is in need of a good trim gauge as stated, or dump the thing and get another bird. CG's are NOT always computed in a fs a/c air file. CG's have to be computed correctly for safe flight. Cargo has to be configured by the Cargomaster of the ship in the same way.

It is physics, aerodynamics & good piloting that can help you keep it in the air. Hope this helped. Try the fuel move first, it is the easiest. IF it's STILL A PROBLEM after 25% of fuel used after the initial rebalancing of the CG, then the AIR file is not good enough, I would think. imho.
Good Day !
Steve Hinson

Posted: Fri Jan 20, 2006 6:20 pm Post subject:

I am afraid some of your post, particularly about how you check the % of MAC beats me. I would have thought that the only way was to balance the a/c up on a knife edge on its geometric centre or metacenter or whatever and see which way it falls! Smile

That is assuming I understood the concept of MAC.

However my problem is different. I have a problem with the minimum trim input I can make. This single minimum elevator trim input I can apply is too high. It is like trying to weigh 125 gms with a set of weights in which the smallest weight is 50 gms, if you understand what I mean! So you have either 100, or 150, but no 125 gms!

Posted: Fri Jan 20, 2006 10:34 pm Post subject:

Can we safely assume that you already went into your ASSIGNMENTS and moved the slider to the far left for Trim Up and Trim Down? Cool

Posted: Sat Jan 21, 2006 9:12 am Post subject:

No you cant! Very Happy

Thanks skip, I did have the slider to full. What is it, this slider? It says "repeat". Is it something like the keyboard echo? Or repeat rate? In which case would it work for the joystick buttons also? Because I always use the joystick buttons to trim. Occassionally the mouse also. And I have had this problem in both cases.

I went through the help files associated with this menu and couldnt locate anything on the funciton "repeat" slider. And there is no keyword search in MSFS right?

Anyway I will fly a few trials and get back with the results. In the meantime ThanX once again Skipperdan.

Posted: Sat Jan 21, 2006 12:07 pm Post subject:

It is the same as the 'repeat' function on the keyboard. Hold it down and it just keeps going...and going...and going...

Exx

Posted: Sat Jan 21, 2006 12:56 pm Post subject:

Experiment with the slider. If the far left is not sensitive enough, just move it a notch to the right until you find a good setting. Cool