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# Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 8:40 AM

Dear users,
I have a problem with a calculation. I have got an assignment. For this assignment I have to redesign the brake actuators for the brake discs of the main landing gear of th fokker 100. I have forgotten how to calculate a force that goes sideways. The sideway forces are created when the lineair actuator pushes the brake disc on the wheels. For the calculation I have a few values.

- Total brake disc mass: 237,84 kg (90% worn brake, CS25.109i)
- CS-25 braking speed is= -3,0 m/s^2
- Assumed distance from neutral position actuator to the wheel= 5 cm
- Maximum take-off weight Fokker 100: 44.450 kg
- Kinetic energy brake discs: 162 MJ
- Maximum actuator force for each actuator: 40.000N
- Specific Heat of he brake disk material: 800 J/kg/K
- RTO test speed: 85m/s, 166 knots
- Effect of air resistance will be ignored, trust reverser and speedbrake on the wing will not be applied.
I have a few questions:
1 - Which formula do I need to determine the force that the actuators need to push the brake discs?
2 - How much actuators do I need in total on each wheel?
3 - What is the Work of each actuator?
4 - What is the Power of each actuator?
To be clear, I DON'T need to know the maximum kinetic energy capability of the brake disc, these questions are aimed only for the actuators. I need to know how much power the actuator need to produce and how much of them I need them on 1 wheel.

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#1

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 8:56 AM

This is not a homework cheat site.

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#2

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 9:14 AM

Thanks for kindness

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#3

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 9:33 AM
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#6

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 10:35 AM

wow, that looks too easy.

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#14

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 2:59 PM

Something is missing here; namely, coefficient of friction between the mating brake surfaces.

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#15

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 4:24 PM

Not only, what is not present is the Torque/Force characteristics of the brake as I already mentioned above.

With the friction coefficient only you cannot start anything if you do not have dimensions and number of disks since those brakes are multi-disk.

For me it is CLEAR as spring water that the participant got a homework and did not make any effort neither to understand it nor to search sources to do it.

I am willing to help ONLY those who make an effort and do not do it the right way by lack of knowledge, they deserve to be helped.

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#16

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 4:24 PM

That is only the tip of the iceberg showing....

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#18

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 5:42 PM

Indeed; there is other stuff missing, too, such as dimensions.

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#17

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 4:47 PM

Thought that looked too easy.

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#4

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 9:58 AM

Your text is not allover understandable I shall make my remarks imbeded:

Dear users,

I have a problem with a calculation. I have got an assignment. For this assignment I have to redesign the brake actuators for the brake discs of the main landing gear of th fokker 100. I have forgotten how to calculate a force that goes sideways (?). The sideway forces are created when the lineair actuator pushes the brake disc on the wheels. For the calculation I have a few values.

- Total brake disc mass: 237,84 kg (90% worn brake, CS25.109i)

Which are te disk dimensions ?
- CS-25 braking speed is= -3,0 m/s^2

In those units you have an acceleration or a deceleration but not speed this value is related to the braking torque and it cannot be related to forces if the torquing capability of the brake is unknown (Nm/N).
- Assumed distance from neutral position actuator to the wheel= 5 cm
- Maximum take-off weight Fokker 100: 44.450 kg
- Kinetic energy brake discs: 162 MJ

In which direction axial or tangential what do you understand by it?
- Maximum actuator force for each actuator: 40.000N
- Specific Heat of he brake disk material: 800 J/kg/K
- RTO test speed: 85m/s, 166 knots
- Effect of air resistance will be ignored, trust reverser and speedbrake on the wing will not be applied.
I have a few questions:
1 - Which formula do I need to determine the force that the actuators need to push the brake discs?
2 - How much actuators do I need in total on each wheel?
3 - What is the Work of each actuator?
4 - What is the Power of each actuator?
To be clear, I DON'T need to know the maximum kinetic energy capability of the brake disc, these questions are aimed only for the actuators. I need to know how much power the actuator need to produce and how much of them I need them on 1 wheel.

I have a doubt about the brake mass and with respect to your notes on the sketch the brake is NOT the rotor but the stator the rotor is the wheel.

What you present is a homework and basically CR4 does not make home- works since their goal is to make the student think and solve problems by himself. However I give you an indication: data you listed are not enough to solve your problem. Think it over again and come with an attempt to solve and you will get support to make it better but you MUST first show OWN effort.

In all machine design books you have ALL what you need from the equations point of view.

We had a couple of weeks ago a student who has as well a brake problem he tried by his own presented his work and I gave him the necessary support to correct it.

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#5

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 10:15 AM

I have nothing to add about brake design relative to what clearly is homework, as any real redesign would have qualified engineers along with DER and their equivalents, in the EU equivalent of the FAA.

I do have Folker 100 interest, as I worked for the company that manufactured parts of the avionics for that airframe.

There was an "incident" where the spoilers were deployed on approach (memory was 3 miles from final landing). The spoilers were armed to deploy when the wheels touched down. The signal came from a tachometer signal based on magnetic inductance sensor, and would trigger the lift killing spoilers on touch down. The auto pilot used a power supply based on the Cuk converter. It happened that the electrolytic capacitors dried out which cause an EMI emission in the audio frequency range below 100KHz. The power cable acted as a transmit antenna of this, which was detected by the spinning wheel system (someone missed the boat on EMI compliance), which deployed the spoilers during flight. LUCKY the pilots recovered from this event, and prevented the crash. My memory was the solution was to not arm the spoilers until the weight on wheel sensor was logically ANDED with the wheel tack system. But my memory is rusty on this, as the story was told as a learning lesson, of "single point faults" resulting in catastrophic events.

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#7

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 10:39 AM

In a real-world situation, the control of "second person check" and "approved for construction" during the design of anything provide a measure of safeguard to prevent duff designs becoming reality. These things are covered by the procedures embraced by the organisation responsible for the design.

So talk to colleagues in a senior position, listen to what these people say, and incorporate these things into the design.

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#8

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 10:44 AM

This should be a relatively simple problem to solve, since the Maximum take-off weight Fokker 100: 44.45 kg or 98 pounds.

<Moving on>

Mathway | Math Problem Solver

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#9

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 10:59 AM

Clue: the original poster has swapped the comma for the decimal point and vice-versa that, supported by incorrect use of commas in the penultimate sentence and various spelling mistakes, suggest a non-English-speaking origin for this post.

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#11

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 12:06 PM

Here you think american punctuation and it is european punctuation the "." is equivalent to the american ","

The value is only 1000x bigger

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#10

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 11:06 AM

<...brake actuators...> It would be interesting to know why the Fokkers need redesigning.

[Takes cover]

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#12

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 1:28 PM

Visibility?! We don't need no stinking visibility! This Fokker can fly in anything!

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#19

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/18/2016 6:48 PM

So it can. ;-)

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#13

### Re: Fokker 100 Brake Disc Actuator Main Landing Gear

01/15/2016 2:57 PM

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