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Aviation Concepts

rc Kits and Accessories

Hydraulic Disc Brakes
Finally, a practical way to keep your model from rolling away! I came up with this powerful hydraulic disc brake system to solve an ongoing problem at RC aero towing soaring events. Large scale tow planes “tugs” are used to pull up gliders / sailplanes up to altitude with a 100 foot line tailing behind the ‘Tug’. Once the tug & sailplane gets up to release altitude, the sailplane pilot releases from the tug’s line and sets off in search of lift. Meanwhile, the tow plane heads back to the field to bring up the next glider or sailplane. This cycle happens about every 3 minutes, often with more than one tug operating on the field. The airfield is VERY active with tugs and sailplanes constantly taking off and landing all day long.

    So, where’s the problem? The problem lies in staging the tug quickly for the next tow. These big Tugs (30-40% scale or larger) are powered with very large displacement engines swinging very large diameter props designed to produce an awesome amount of thrust. While these big engine and prop combo’s are ideal for towing giant scale sailplanes to altitude, they have a tendency to continue to roll even at idle particularly on close cut grass fields or on pavement. Once the tug lands and taxies back into position for the next tow hookup it needs to reliably and positively STOP when the end of the tow line is at the front of the next glider that is staged. At this point the line can be safely and smoothly connected to the next glider to be towed and thus start the tow cycle all over again. If the tow plane can’t stop or the line isn’t grabbed and held back, then the tug usually has to “go around” or taxi back down the field again to drag the end of the 100‘ tow line into the correct position to complete the hookup on the waiting sailplane. The turning radius of these large scale Tugs doesn’t help either. Needless to say this fumbling about on the field can be dangerous and causes unwanted interruptions and delays on an otherwise smooth running flight line.

     The hydraulic brakes are very similar to what’s in your car and they operate in much the same manner. There is a small master cylinder in which a servo pushes on a lever and forces brake fluid down to the calipers and squeezes the brake pads together around a disc. Unlike pneumatic “air” brakes, they don’t need to be replenished between flights and hydraulic systems require far less maintenance than pneumatics. Air is thinner and more likely to leak out past the o rings. Air is compressible, oil is not and thus oil “hydraulic” brakes are more powerful than even mechanical or electro mechanical brakes. “I’ve experimented and tried them all.”

     These brakes are intended to be used on (1/3 scale or larger aircraft) as a parking brake at idle to prevent the model from rolling away while the engine is idling. They are proportional and can be used to slow down a large scale model weighing 30 to 50 pounds after landing or taxiing. Independent wheel braking such as used on full scale tail draggers / tow planes can likely be achieved by purchasing an additional master cylinder and servo… Note; this unit is  very poweful and slamming on the brakes (on a taildragger) while moving at consideable speed can tip the model onto its nose and cause a prop strike.

     At this time, these brakes are designed to be mounted on fixed landing gears (trikes and tail draggers) that uses aluminum bent plate or flat composite landing gear with a 1/4” to 5/16” (6mm to 8mm) diameter axles. Note: air filled wheels may not be useable due to the drilling required on the wheel hub. Drilling the wheel hub may violate the air tight integrity of the tire or rim. Also note that these brakes cannot be used with wheel pants (fitment issues), wire landing gears, struts or retracts.   

Specs:
Disc diameter -------------- 2 3/4" to 3" (depending on model gear dimensions)
Weight----------------------12 oz. (without servo, linkage or fluid)
Servo------------------------170 in/oz torque (minimum)
Brake fluid------------------DOT 3 or DOT 4

Master cylinder

Caliper mounted to gear

Disc and caliper

A custom made spindle bolts onto the wheel and has a hex shape end that slips through the hex of the disc. This allows the disc to run straight and true if the wheel wobbles on the axle.  This design also simplifies the ease of installing or removing the wheel from the landing gear. 
Whats in the Kit
The kit includes the following components: One master cylinder, brake calipers and mounting brackets, discs, spindles, new longer axles with wheel collars, Five feet of hydraulic brake line with festo fittings and bleeder valves, filling syringe with hoses, hardware package and manual. What's not included is the wheels and landing gear, pushrod, servo and brake fluid.

Product

These are cusom made to order to fit your models landing gear and wheel combinations. Not all wheel / gear combinations may work. Scroll down to see current kit offerings to purchase.  To order a custom wheel / gear combo, please contact us for more info.  (Custom orders not listed below will require you to send us the landing gear and wheels. 


Hydraulic Disc Brake Kit for

Hanger 9 Decathelon with                           $469.95

Du-Bro 7" T.L. wheels


 

Hydraulic Disc Brake Kit for

Top Model Bidule 170 with                         $495.95

Du-Bro 8" T.L. wheels

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Hydraulic Disc Brake Kit for

Top Model Bidule 170 with                         $529.95

Aeroworks 8.2" x 3.2" wheels