I started flying in (relatively) recent times with (relatively) recent airplanes. These recent airplanes had comfy seats, lots of buttons to push on the panel, and of course, toe brakes.

Toe brakes, like steering chains on your tailwheel, are one of those things you just don't question. Everyone including the most knowledgeable internet experts agree heel brakes on an airplane was just a terrible idea. 

Sure, once in a while some very high-time Cub driver speaks up and says they actually prefer heel brakes. Thankfully those same internet experts agree once again that the lonely Cub driver really doesn't know what he/she is talking about. Just like free castering tailwheels, hand propping your engine, and steam gauges, heel brakes are the work of the devil and should be avoided at all costs.

(If you don't know this reference, please go watch the cinema masterpiece called The Waterboy)

 

A ferry pilot dropped off my EAB WagAero J3/PA-11-like Cub to me thirteen years ago. Like most new Cub owners with low tailwheel time, I was initially pleased the builder decided to fabricate toe brakes as it would be one less thing I would have to adjust to. 

Unfortunately, those toe brakes in my little CUBy were the catalyst that led me to down the deep rabbit hole of EAB design and build. I now have thousands of hours 3D modeling new airplane parts, CNC'ing said parts, and eating PB&J sandwiches with a TIG torch in my hand.

I can see your head tilt from here; let me explain.

Those little toe brakes did not work for sh*t.

• The foot pressure point was wrong and it was darn near impossible to stay off the brakes while providing rudder input.
• The linkage did not provide enough leverage to the master cylinder (located on the rear rudder pedals). The masters were bled properly and worked well from the rear seat. The lack of linkage leverage actually reduced braking power rather than amplifying it.
• The rotating foot pad was fabricated in such a way that all of the braking force traveled through questionable tabs (which eventually broke off).
• Best yet, when the rudder pedal was at full deflection the toe-brake-toes would hit the firewall. (Look at the firewall on toe-brake converted Cubs; I bet you $2 you will find toe-brake indentations in the firewall)

 

Bad initial implementation:

...leading to some (now obvious) failure points:

 

First Fabrication

To be fair, I had been drawing, machining, welding, and fabricating parts for roadracing motorcycles for over 15 years before taking my first Cub flight. That said, I had never tried my hand at anything EAB. Using a very old version of AutoCad and a local water jet service, the beginning of my demise was cut in fresh 4130:

My trusty TIG welder was dusted off and was put into service:

What started out as a vague idea became real in 4130 tube, plate, and grip tape:

These new & improved toe brakes served me well enough for the next few hundred hours. Truth be told, they worked only marginally better than the as-delivered design and suffered from similar issues, but they did indeed work better. These new parts allowed me to learn my Cub both inside and out and spend invaluable time aloft in the thin Colorado air.

These toe brakes were my first Cub part designed, built, and tested marking the start of my EAB design build addiction.

Design Flaws

Over the subsequent years I was able to study the original J3, PA-11, PA-18 and experimental brake designs. All were better than what my airplane provided but most still utilized various linkages and other oddball design elements. (Side note: I really like how the SQ-2 toe brake system works, but that is a different discussion...)

The toe-brake conversions for the Cubs were all interesting, however they all suffer from a simple inherent design flaw: the length and mount placement of the Cub rudder pedals all but guaranteed the toe-brake would hit the firewall at full rudder deflection. The rudder pedals do not hit the firewall on a stock Cub. But, graft on an extension that is required to rotate independently of the pedal and whammy, you are banging up against the firewall at the exact moment you need brake pressure.

Eventually I ran out of immediately pressing issues with my Cub and my attention once again returned to my inadequate braking which only worsened with the installation of 26" ABW Bushwheels. 

My brake requirements narrowed in on the following:

• I wanted the brakes to actually work
• I wanted to stop hitting the firewall with my pedals
• I wanted to be able to apply brake pressure independent of rudder input
• I wanted to remove the requirement to lock rudder input while braking (more on this below)

By now, you might have guessed all signs are pointing to heel brakes, but it took me a while to come to this realization.

Rudder Pedal Influence on Braking

In most cases for most pilots there is little need to break the connection between the rudder pedal and the brake application. However, fly long enough and gain a soft enough touch in your aircraft, you begin to realize something odd:

Braking force can only be applied to a toe brake if equal force is applied on the opposite rudder.

This sounds odd at first and I am guessing you are already shaking your head in disbelief, however stay with me. The next time you are in your trusty Cub-like toe brake equipped airplane with stock-ish rudder pedals, try the following experiment:

• Attempt to apply full right brake pressure with your left foot firmly planted on the floorboard and NOT on the left rudder pedal.

Another thing to try:

• Attempt to apply full right brake pressure without actuating the rudder while your left foot planted on the floor and NOT on the left rudder pedal.

Spoiler alert: That can not be done; you will simply push your rudder pedal to full deflection until you hit the rudder stops. Only then might you actuate your brake, slightly.

The only way to get the master cylinder to compress around the pivot point at the rudder pedal is to hold opposite pressure on the <other> rudder pedal. In essence, all of the force required to compress the brake master cylinder is being transmitted down the rudder cable, through the rudder horn, back down the opposite rudder cable and to your opposite foot.

Pilots everyday everywhere do this unconsciously when they pick their heels up off the floor and use both legs to actuate the rudder pedals and toe brake pivots at the same time. It is not difficult and this is normal operation for most.

I wanted the impossible.

I wanted to have a feather light rudder feel while mashing the brakes to the max. I wanted to be able to stomp on the rudder while applying only slight brake input. In short, I wanted to break the rudder-brake connection entirely. I did not know it initially, but what I ideally wanted was an updated version of the 1930s Piper heel brake design.

Maybe that crusty old Cub driver who was ridiculed ruthlessly by the internet experts was actually right!? Perhaps, just perhaps those that came before us really did know what they were doing?

 

Old Idea, New Tool

Armed with a design direction, it took mere minutes (ok, hours) to 3D model my first prototype:

The design uses a standard Matco master cylinder and is entirely self contained so it can be mounted anywhere on the floorboards. This design also has a provision for a parking brake by pushing a pin through the pedal into the base.  The pedal and base were envisioned to be CNC'd 6061 T6 anodized aluminum.

After a few 3D prints to test fitment then a bunch of green-backed aviation units to buy some CNC time, I had aluminum parts in my hands:

Obvious in the last photo, all linkages were removed thus removing the rear controls. However something more important was gained: a simple brake system that that actually works.

How well does it work?

• I now have far more braking power than I need for 29" bushwheels
• I can brake independent of rudder, and my rudder feel remains absolutely uninfluenced by brake application
• I found a location on my floorboards that allows good brake feel independent of whether I am wearing lightweight sneakers or heavy boots
• I have yet to touch my toes to the firewall even when at full rudder deflection

In short, this design is exactly what I prefer.

Perhaps an airplane with no starter, no toe brakes, and no tailwheel steering chains is not nearly the devil as I was led to believe?

(wait, did he just say "no starter"?) 

 

 

New Pilots Please Read:

The above are my unique preferences for my unique environment on an experimental aircraft. It is illegal to make any unapproved modifications to a certified aircraft.

Please do not remove anything from your aircraft, and never fly an a configuration you have not been trained on. It may sound like I make light of advice provided on internet forums, but until you really know your aircraft and your mission, airplanes such as mine can be dangerous to your health. The airplane itself is not dangerous; it is a pilot who has not yet been trained on its natural behavior. The natural behavior of this airplane is to land you in the ditch then the hospital if you do not spend quality time with a quality tailwheel instructor. Even then, small steps will save you big repair bills.

Now, go forth young grasshopper and tame the beast that is a highly modified tailwheel aircraft!