Brakes...Are 2 calipers per wheel better than one

[turboplanner]

Hard to control side by side Tomo - you're talking about individual brake modulation - we're more used to feel through the toes, and the linkage can be adjusted to make the travel longer, and so less sensitive.

 

Master cylinder area, VS Wheel cylinder area

 

The issue is leverage - if you double the wheel cylinder area, but leave the master cylinder the same, you double the leverage. This would explain why Jabs with dual calipers (wheel cylinders) can be made to lock up more readily than with single calipers. With more money to spend a designer might fit a new master cylinder of a slightly larger size to bring the forces back into balance.Since so much theory has been bandied around, much of it relating to either higher performance braking, or systems with mis-matched components, the answer to the original question is probably to have a brake designer design a matched system based on the operating weights, surface coefficients, and speeds of the particular aircraft.

 

 

[Jabby]

Jabiru Brakes

 

Hi Guys Sorry for not replying sooner. I am at present travelling round Australia and sometimes do not have service. However you want to know more about these fab brakes. Basically you buy the whole kit which includes tyres tubes wheels calipers discs fittings and pipes They cost us about $1300 Aus delivered to your door.If you have any questions email George @ Matco mfg and mention my name (Mike Roche) He will be more than helpful.I d'nt have any part Nos with me unfortunately You w'nt regret.Cheers Mike (Jabby) PS You can try calling me on 0408203362 for more info.

 

 

[jetjr]

Tomo, I think Boyd May used to offer a dual master cylinder - fairly expensive and you also had to get extra lever etc from Jabiru.

 

With the steering nosewheel you could easily apply a fair bit of sideways force to it.

 

Not a great thing to do in a Jab.

 

 

[bushpilot]

Just looking at some formulas I have and some other literature about break forces and caliper setup, has anyone noticed their jabiru pulling to the right after hard braking, especially larger pilots one up?

Generally only happens with mis-adjustment; i.e. one side's adjustment bolts pulled up more than the other side.

 

 

[Relfy]

The reason i ask is if the pilot is sitting over the left wheel in heavy braking, that brake caliper/disc combo will have to overcome a greater frictional force to brake as per the right side wheel.

 

I've tested semi trailers locking up from 70-90kph (i've got some interesting vids to post when i learn how!) and we measured the slack adjusters and other braking components and could work out the brake force each wheel could apply to the drum. We weighed all wheels and worked out that on some wheels, the overall available braing force was not able to overcome the weight applied to that axle side and hence, when looking at the video, the reason why that wheel did not lock up like the others.

 

I was curious because I am going to work out the braking force and coefficient of friction for a jab when locked up and see what distance it will pull up in when you brake at 100% brake force application. Now where's the nerd symbol...aha, there it are. It would be interesting to work out what distance you could pull up on bitumen, grass and gravel given different touch down speeds just for reference.

 

 

[bushpilot]

We got tired of taking the wheel spats/fairings off every time we wanted to do a brake adjustment. So did a simple mod with holes drilled on the inside surfaces to allow access to the caliper adjustment bolts with a socket. Works a treat: Just pull each bolt up the same amount - and if you go too far and pads drag a bit, just back them all off a little... 2 minutes a side. Photos here show the result.