THE DESIGNEE CORNER By Antoni (Tony) Bingelis

EAA Designee Co-Chairman 8509 Greenflint Lane Austin, Texas 78759

A BIT ABOUT BRAKES...

There are always some exceptions, naturally.

Mechanical and Hydraulic

One of the simplest installations is the type employed on some gyrocopters and on some of the early Jeanie's

.CJVERY AIRPLANE SHOULD be equipped with brakes. There never seems to be any doubt about this in the builder's mind when he is building a fast or a sophisticated aircraft. But, just let him start on an antique, a minimum type of bird, or an ultra light, and he begins questioning the worth of a brake installation. Why? There should be no doubt at all! All aircraft should have operating brakes. The days of yesteryear with their unimproved sod field, and sparsity of people and planes, provided a different environment and operating situation. Those were

times when airplanes landed in a 3 point attitude at 30 or 40 miles per hour under calm conditions with the tail skid

acting like a dragging brake. It even took plenty of rpm's to taxi under such conditions with the skid digging into the turf. Nowadays, with tail wheels, or any other arrangement of ball bearing equipped wheels, the airplanes roll nice and easy. They are much harder to slow down and stop on pavement. Not only that but with many

other expensive airplanes parked all about the area, you have a liability problem to think about, too. It could ruin

your whole day to roll helplessly into a parked 310 with your brakeless Splinter Sport Special (even leaning back hard won't get you stopped). THE BRAKING PRINCIPLE

The essential ingredient in any brake system is controlled friction, that is, if you could cause some object (brakeshoe) to rub against some part of the rotating wheel assembly with some degree of control, you would have the makings of a brake system. The principle of operation of all brakes is essentially the same. The only real difference is in how the force is applied to the brakeshoe or puck.

Teenies. A single pivoted shoe was installed over the nosewheel tire. By means of a lever and a control cable to the cockpit this pivoted shoe could be forced against the rotating tire causing considerable friction and a braking action. The amount of braking action naturally is limited as only one wheel is usually involved in such a rig. It is reasonably effective for the gyrocopters but its worth on an aircraft is debatable. Still, even such an installation is better than nothing. Aircraft equipped with single ignition engines (VW's and other automotive types) do not require run-ups at higher rpm's for the purpose of checking the mags! Why not? If the engine is running you are already "checking" the one and only magneto ... so who needs heavy braking action?

A better system of mechanical brakes is the individually operated brakes with units attached to each main wheel. Go-Cart wheels and brakes are being used in increasing numbers on low powered single seaters now being built, and they are quite effective for such light airplanes. These brakes are of the expanding shoe type, with a simple brake drum bolted directly to the wheel. The brake actuating lever on mechanical brakes usually operates equally well when moved in either direction, therefore, you do have some choice as to how it is positioned in the wheel. After the brake cable is attached to the lever, you will notice that no matter how it is positioned, an immediate and major change in direction for the cable must be made to route it up the gear leg. This means that the builder must install a pulley at this point. It also means that a bracket to mount the pulley must be welded or .bplted to the lower landing gear leg at just the right angle

to route the cable from the control lever around the pulley and up the landing gear leg. If the change in direction

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TYPES OF BRAKE SYSTEMS

For our purpose, we can divide all brake systems into two groups, mechanically operated systems and hydraulically operated systems. Either type could do a commendable job for you if properly installed and adjusted.

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Although some people think the mechanical brakes are cheaper, there is usually no denial that they can be more complex to install and to adjust.

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MECHANICAL BRAKES

Sometimes I wonder if installing mechanical brakes is less expensive when you add to the initial cost of the brake unit, the linkage and the welded brackets, cables, levers, and all the pulleys required to complete the installation.

FIGURE 1 SPORT AVIATION 25

for the cable at the lower gear leg is not severe it may be possible to use a copper tube brazed to the gear leg to

accomplish the minor deflection. Motorcycle shops have plenty of brake cables and throttle cables enclosed in a good housing that can be adapted. 1/16" or 3/32" air-

craft extra-flexible control cable may also be used. At the point where the brake cable enters the fuselage another pulley will be required. It too, should be aligned and installed to take a considerable amount of the load due to another major change in direction. If you plan beforehand, you might be able to install the brake cable with as few as 3 pulleys per each brake unit. The pulleys should be the ball bearing heavy duty kind with a diameter of about one inch, certainly less than 1 1/2". Mechanical brakes can be operated individually by pedals or collectively by means of a single brake handle. For my part the individually activated installation is more effective and desirable. Even though not as important with tricycle gear installations as with tail draggers, individually operated brakes always provide better control. The cockpit end of the mechanical brake system usually terminates at individually heel operated pedals. I don't believe I have ever seen an installation of mechanical brakes hooked up for toe pedal operation. The complication is that the movement of the rudder pedal makes it difficult to avoid exerting an unwanted pulling force on the actuating cable. This could be minimized if the brake cables were routed around a pulley mounted close to the brake pivot point and then to a lever attached to the hinged toe pedal. I don't know how effective it

To show you that there is practically nothing new under the sun, take a look at the highly improved version of the

Stagecoach or Conestoga wagon brake installation on my Scooter. See Figure 3 and 4. The system is absolutely foolproof and reduced to one of stark simplicity. It has to be the simplest aircraft brake systems ever devised . . .

would be but it should work. See Figure 2.

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FIGURE 4

with an integral parking brake installation yet! Just reach

out and grab hold of the brake handle you want to use and

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