Brakes

P

paul day

Charter Member
I have just purhased the Razbam A4 Skyhawk (at half price) and i have a problem. With it throttled down it races away and even with the parking brake applied it still creeps forward. Is there any alteration i can make in the aircraft CFG to tesolve this problem?

Regards Paul Day.
 
I know that if the CFG power/static thrust is over the top the brakes won't hold. You know this is the case when you can set just above idle and still take off and hit 400mph. Also sometimes the contact points will prohibit the brakes or steering to work well as they won't tell the game the thing is fully on the ground. More simply go to the Toe Brake line on the CFG and see if the scalar is at 1.00 or close to it.
 
Paul, I also own the Razbam Skyhawks, and have removed them from my computer due to flyability issues; I may re-install and take a look at the configs now that I am learning how they work. I will let you know what I come up with.
 
These are the entries i have for the brakes in the aircraft CFG.

[brakes]
toe_brakes_scale=2
parking_brake=1

Regards Paul Day.
 
Try putting the scale to 1.00. I'm not sure FS recognizes any number higher than that. If it works and is too harsh you can reduce it. I find 0.8 works well most of the time.
 
One thing to check is to make sure the brake scalar does not have a - sign in front of it. In such cases (an Ito plane had this problem) application of the brakes will cause the plane to accelerate and applying them will cause it to decellerate....

Cheers: Tom
 
I have the Razbam Skyhawks (package 4 if I recall correctly) and have had no problems out of it. The plane is a bit squirrely on take off, but that is realistic to the plane...those tall landing gear struts made the A-4 a real fun ride during take off runs.

OBIO
 
FS recognizes numbers higher than 1.0 on the toe_brakes_scale. We use 2.23 on the Viggen to get it to stay still even with full after burner.

Cheers :wavey:
 
I've had this problem with a number of aircraft, ie: too much power/thrust at idle.

While I can see how increasing brake power would help, it seems a better solution would be to fix the idle somehow.

Why do some aircraft sit still with the engine idling and brakes off while others creep with full brakes on and taxi at 100kts with brakes off?
 
Depends on the aircraft, engine type, and flight model, but generally it is because you have too much thrust for the ground condition and maybe because you need to adjust power settings.

By default, jets and turboprops are not set to ground idle when on the ground. You must do this by pulling the (prop condition) lever back, or using cntrl+shft, and tapping F2 to get to ground Idle. Good example here is the default KA350. Pull up the throttle quadrant and watch the prop condition lever as you make adjustments.

AVGAS engines with variable pitch blades are typically set to minimum (fine) pitch on the ground but you still control it. Push the prop condition lever all the way forward, or use the keyboard to set props to fine. (cntrl+F4) If you still experience forward motion with props set to ground fine, then it may be the pitch is not fine enough to reduce thrust. This may be by design for this aircraft, but maybe the aircraft.cfg can be changed to reduce this.

Take the KA350 for example ... the aircraft.cfg Propeller section I have shows minimum_on_ground_beta = 1.0 degree. This virtually eliminates forward thrust at ground idle. Check your problematic aircraft cfgs to see what they have. But do ensure that you are reducing your engines of whatever type to a ground idle.

Most FM's have the corresponding air file table 511 beginning at 15 degrees so anything less will allow you to sit still.
 
Thanks for all the input to this problem. Looking on the Razbam site i am not the only person experiencing this problem with the A4 Skyhawk. It does not happen with any other models in their range. I have not got this issue with any other aircraft, jet or prop but taxing at 30 knots and accelerating tend's to bend a lot of metal and on an aircraft carrier usually ends up ditched over the side.I think the answer still lies in the aircraft CFG but where, i am at a loss.

Regards Paul Day.
 
Well, I thought the answer was in my response but maybe not.

I do not have this aircraft so I am speculating. If you could post the GeneralEngineData and TurbineEngineData sections, maybe I can see a clue.

You can try decreasing "static_thrust =" a bit (3500 or less), and try reducing "min_throttle_limit =" if not already negative.
 
heres the TED and GED for the TA-4 (tends to sit on 0.1 knot with parking brake on, and once off slowly accelerates with zero throttle input)

[GeneralEngineData]
engine_type=1
Engine.0=-3.000000,0,4
fuel_flow_scalar=.30
min_throttle_limit=0.000000

[TurbineEngineData]
fuel_flow_gain=0.002500
inlet_area=10
rated_N2_rpm=29920.000000
static_thrust=11200.000000
afterburner_available=0
reverser_available=0.000000

This is it for the A-4K

[GeneralEngineData]
engine_type= 1
Engine.0= -3.000, 0.000, 3.000
fuel_flow_scalar= .15
min_throttle_limit=0.000000

[TurbineEngineData]
fuel_flow_gain= 0.0025
inlet_area= 10.000
rated_N2_rpm= 29920.000
static_thrust= 7700.000
afterburner_available= 0
reverser_available= 0.000

st seems high as the J52 P8A (A-4E and up)was rated at 9300, A-4m skyhawk II was uprated 11,200 lb
 
This is what i have for the A4 Skyhawk pack 4

[GeneralEngineData]
engine_type= 1
Engine.0= -3.000, 0.000, 3.000
fuel_flow_scalar= .15
min_throttle_limit=0.000000

[TurbineEngineData]
fuel_flow_gain= 0.0025
inlet_area= 10.000
rated_N2_rpm= 29920.000
static_thrust= 8400
afterburner_available= 0
reverser_available= 0.000

This is from the Douglas A-4L model which is one model i know has this issue, i hav,nt even checked the other models as yet.

Regards Paul Day.
 
This is somewhat related. For the Air Brakes, what is it that controls the pitching effect when deployed? Some cause up or down pitch, just slower speed, or sometimes a severe down-draft effect.
 
Jets can have a lot of residual thrust at idle, though the high bypass turbofans are the biggest offenders here. Given unlimted runway I have sometimes mused that the 747-400 might be able to become airborne at idle thrust at very light weights.... I think the issue here may also be related to the way runway and wheel friction is modeled in FSX. Simply put FSX will cause the wheels to lock and slide much too easily. Note in external view whether or not this is occuring.

I agree with Milton that some of the cure may lie in the idle thrust numbers.

Pitch with air brakes is in the air file section 1101 (primary aerodynamics) Cm-ds, pitch moment spoilers.

Cheers: Tom
 
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