Heel Brakes

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Terry Hand
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Joined: Thu May 18, 2017 2:37 pm

Heel Brakes

Post by Terry Hand »

And Now For Something Completely Different -

After a too long hiatus on my Pietenpol project, I am back at it. I need some constructive ideas.

I have made the decision to go with manual drum brakes. I did not want super strong hydraulic brakes that would either flip me over if I stomped too hard or leave me stranded if I had a leak. Simplicity was my goal. In addition, I am installing rudder pedals in the rear seat of my steel tube project. I have steel tube tail feathers (a la Scott Liefeld, so it is a long-flown, proven design). I am comfortable with rudder pedals over the rudder bar.

I have seen the Bill Rewey style brake pedals, and as nice as they are, they will not likely work with my setup. So I have elected to go with heel brakes. I have a set of Champ pedals that I am thinking about using, but the rest of it I am still mulling over. Does anyone have any thoughts or ideas on the best way to fabricate this set up? Or better for a non-engineer, non-gearhead pilot such as myself, got any pictures?
3CD53954-64AD-4ECB-87BC-6A3B826E5E6D.jpeg
Thanks in advance for any help that you may provide.

P.S. Come on, Oscar, I know that challenges like this get your engineer juices flowing. ;0)
Semper Fi,

Terry Hand
Athens GA
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taildrags
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Re: Heel Brakes

Post by taildrags »

Terry; I have seen pix of some very elegantly executed heel brakes and if I were building a new Piet I would consider that setup. That may be partly due to the fact that my first training, and my first supervised solo, were done in a J-3 with expander-tube brakes with heel actuation. The expander tube brakes are just about the right 'strength' to do what's needed without feeling like you could go over on the airplane's nose if you stomped them. That said, I've never gotten the feeling that the Clevelands on 41CC were going to nose me over even though they likely have the power to do that since they are from a C172, an airplane twice the gross weight of the Piet. I have grown to like the rudder bar setup but have never flown a rudder bar with heel brakes so have no personal experience with that combo.

I'm currently down in Texas for this week, visiting with family, and it's not convenient for me to dig through my reference material for pix of the heel brake setups that I think are nicely executed, but can do so when I'm back home. I have thought up some Rube Goldberg-ish setups to translate mechanical fore-and-aft motion into brake cable motion for mechanical drum brakes, but none as nice as the setups that others have actually built and flown. In particular, there was an award-winning scale Jenny with a Geo engine on it that had a very nice heel brake setup for the drums on the spoked wheels and those pix are the ones I'll try to locate first.

Oscar Zuniga
Laredo, TX (for the week ;o)
Medford, OR (regular home)
Air Camper NX41CC, A75 power
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Terry Hand
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Re: Heel Brakes

Post by Terry Hand »

Oscar,

At your leisure. Have fun with family.

(I figured you would have a picture or two.) ;)
Semper Fi,

Terry Hand
Athens GA
danoliver
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Location: Cincinnati

Re: Heel Brakes

Post by danoliver »

I’m still in the building stage so who knows how well my setup will actually work but for what it’s worth here’s a couple shots of how I did mine. The design is inspired from pictures on West Coast Piet of Charlie Miller’s design.
1919F80B-4137-4798-BB89-715391BCE475.jpeg
It’s really hard to get a good picture under there.
38863688-CD5F-4D22-AF0F-B916D789BF43.jpeg
A48A9EF5-43F3-4CF3-81C4-9C62BC15EC81.jpeg
And here’s the mess makes underneath.
37C3CB9C-CF34-4FC5-90C2-0A5E15659D5E.jpeg
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taildrags
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Re: Heel Brakes

Post by taildrags »

Dan; does the brake cable go around a pulley to change direction before entering the outer sheath? Looks that way but I can't be sure.

-Oscar Z.
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Richard Roller
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Re: Heel Brakes

Post by Richard Roller »

Dan. Are the red straps control stops?
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Richard Roller
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Re: Heel Brakes

Post by Richard Roller »

By the way Terry, good to see you back on the site.
danoliver
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Re: Heel Brakes

Post by danoliver »

Oscar, the cable does not currently go around a pulley. It just bends 90 degrees around a wood curve. I figured that would be a simpler installation (always on the quest to reduce parts count). However, I made the dimensions match that of a pulley so that if it proves to be a problem then it would be relatively easy to add them.

Richard, yes the red straps are my rudder control stops. I was going to add the wood blocks in front of the rudder bar as stops but they would of been like an inch and a half deep. looked like a lot of block! So I decided to try straps instead. The only thing I could think of that might be an issue is if the strap slid in or out on the bar then your travel would lessen. That's why you see the safety wire clamping them in place.

None of this stuff has been tested in the field mind you.
I posted mostly just to point out that heel brakes can also be installed sideways.
Another cool sideways set up is pictured on West Coast Piet under Alan James.
Erik (Woody) Woodson
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Location: New Orleans La

Re: Heel Brakes

Post by Erik (Woody) Woodson »

How timely Terry, I was trying to remember which project these went to. :lol: I'm listening, great ideas, I think Gary Boothe's plane on westcoast piets has some good brake ideas as well but I am looking at the sideways install.
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IMG_0009.jpg
bob turner
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Re: Heel Brakes

Post by bob turner »

Bump. After trying several geometries I have decided that something like this (only hydraulic) would be optimum. Semi-easy for Cub drivers to get used to.
Hopefully someone can steer me to the “West Coast” photos/info?

My old Cub Scott masters will not fit anywhere down there, even if I pulled the (inaccessible) front seat.
bob turner
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Re: Heel Brakes

Post by bob turner »

There just isn't any room anywhere for a hydraulc master cylinder with heel brake. Today I decided they would have to be in the slipstream. Guess percentage-wise, it will be a blip on the profile drag. Mocking it up this week.
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KenBickers
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Re: Heel Brakes

Post by KenBickers »

Bob,

"Outside box, think we must," Yoda might say. Or put differently, there's more than one way to skin a cat.

I have heel brakes and master cylinders under the front seat on my Piet. I used AirHeart Small Master Cylinders. They are attached to flagpole heel brakes, rather than lever arms.

Here are a couple pics, from the top and the side.

Cheers, Ken
Attachments
heel brakes (top view).JPG
heel brakes (side view).JPG
bob turner
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Re: Heel Brakes

Post by bob turner »

Ours has that bar, going completely across the aircraft. I can see right now that I need higher, more Cub-like pedals. The ones in front would be perfect, but are too wide.

Will I run into trouble raising the pedals and cables a couple Inches?

Tough to see exactly what you did there, but it is clear you have individual pedals. The bar seems like a not-so-good idea.
Vagabondpilot
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Re: Heel Brakes

Post by Vagabondpilot »

Looks like a nice installation, but I don’t see how it works. It appears the heal pedal is under the front seat. What am I missing ?
bob turner
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Re: Heel Brakes

Post by bob turner »

Well, I opted for an "under the floor" installation. I mocked it up today, and two of us tried it out. Seems very "Cub-like" to us.

The actual installation will be very "dirty" for the test flight period - then maybe we will make some little streamlined blisters. Maybe.

I get the feeling that most Pietenpol mishaps are brake related?

Also, I now know why the bar, instead of individual pedals. Thanks for that - search works ok except for this "Matronics" thing.
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KenBickers
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Re: Heel Brakes

Post by KenBickers »

Vagabondpilot,

Yes, the "flags" of the flagpole setup are under the front seat, but only barely. As with all heel brakes, when you want to apply brakes, you shift your heals just inboard of their regular, natural position. After a couple minutes of practice, it is as natural as the motion to slide your feet up when using toe brakes.

Cheers, Ken
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taildrags
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Re: Heel Brakes

Post by taildrags »

Ken; I'm with you. My first supervised solo was in a Cub with heel brakes operating the old expander tube actuators, which provided sufficient braking power on the grass strip that I was operating off of in the low-powered Cub. I didn't even have to think when it came time to apply braking... just did it. It's quite the same thing today in my Piet with toe brakes. I don't even think about it. Both arrangements work just fine.

Oscar Zuniga
Medford, OR
Air Camper NX41CC, A75 power
bob turner
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Joined: Thu Dec 07, 2023 2:03 pm

Re: Heel Brakes

Post by bob turner »

I got all the mechanical stuff done - all that remains is to add hydraulic fluid and test. As I mentioned above, I could not picture a clean installation inside the cockpit, so chose to mount the Scott masters under the belly. Grove 95-1/2 would work the same, with the same mounting.

I also straightened out a tailwheel kingpin problem, and will, within about the next two weeks, begin taxi tests. I have to figure out the com radio, which shouldn't be a big deal even if I have to re-wire it, and the final step will be yellow and orange, so folks can see us as we commit aviation with this thing. Photo of the installation below - not nearly as ugly as I first thought it would be. And I can put them in little fibreglas bomblets if I really want to go to the trouble . . .
DSC03408.JPG
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KenBickers
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Re: Heel Brakes

Post by KenBickers »

Clever! You may find the O-rings will stay healthier if you periodically wipe off the plungers after landing/taking off on turf runways and during heavy pollen seasons.

Cheers, Ken
bob turner
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Re: Heel Brakes

Post by bob turner »

Thanks. Where are these O -rings? Under the bungees?
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KenBickers
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Re: Heel Brakes

Post by KenBickers »

Master cylinder plungers.
bob turner
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Re: Heel Brakes

Post by bob turner »

These are Cub type (Scott) master cylinders. No O rings, no reservoir. The proper replacement would be the Grove 95-1 & 2. Those indeed do have O rings. I have not yet studied the Grove units (which are on my Cub via field approval) to see if the outlet and reservoir is compatible with my mounting scheme. The Scott end bells are rotated by about 80 degrees.
bob turner
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Re: Heel Brakes

Post by bob turner »

Got the engine running yesterday - taxi tests with the Scott masters were successful. Test pilot says they feel just like the J-3 brakes that we are all used to.

Now working on the radio, and then a little paint, assembly, and test flight. We have an application for an amendment to the operating limitations so we can do the first few flights close to the shop - we'll see how that goes.
bob turner
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Re: Heel Brakes

Post by bob turner »

We have been taxi-testing the heel brakes for a few weeks now. I finally stretched my 83 year old legs in there, and found that we still have a few problems - the brakes are in the right spot, and are just like J3 Cub brakes even though the wheels themselves are ancient and obsolete Cleveland discs.

But the rudder bar is too low to enable Cub-like control using both rudder and brake. I have temporarily put pedals in, which produces a torsion load on the bar and a shear load on the pivot bolt. I haven't done any computations yet, but so far that seems to be the solution to Cub-like directional control.

I have extremely limited experience with experimental airplanes in general, and Pietenpols in particular - never flown one. I think my 6,000 Cub hours will help a lot when test flight time comes, but I am about to decide that most Pietenpol problems are related to inadequate braking. I would be happy to entertain some other major source of grief that eclipses any perception that directional control is the major problem.

I was just visiting Grove yesterday - they now have a good supply of the Scott-style master cylinder, part numbers 95-1 and 95-2, which is a better replacement for the Cubs. I run them in my Cub, and consider them far superior. We put the old masters on the Pietenpol because we had them, but if we decide to keep the Piet (unlikely) we will put the Grove parts in.
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