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Brake upgrade for a Turbulent?

10 Posts

I’ve bought a Turbulent project and the biggest job – I hope – will be to fix the landing gear.

I don’t like to think too much about how the axles became so warped. Two thoughts are that they may have been ‘rescue’ undercarriage from another plane that was written off. Another is that they have had the screw at the end brazed into position, possibly destroying the temper of the axle. Either way, the relatively spindly mounts on the spar seem in good condition and my inspector is happy with the condition of the spar.

So, clearly the axles need fixing and one of the brake backing plates needs replacement too – which is within my ability but I suspect it would be easier simply to replace them. They’re operated by bicycle cables and I’d prefer not to change that aspect of the system.

The wheels are 5"; the axle is 1" and the brake hole spacing is 3.75" diameter. The current brake drum is 4" internal diameter.

Does anybody have any suggestions as to what they would replace the brakes with? Cost is a consideration. It’s been put to me that I should opt for disc brakes.




I can imagine weight and complexity are big issues for a Turbulent and brake performance may not be paramount, but for what its worth I might take a look here – because its really good quality stuff.

Applications

5 inch Wheels

Axles

I note that the axle diameter spec’d for a lightweight 5 inch wheel is 1.25 inches – which would be less likely to bend.

Last Edited by Silvaire at 09 Nov 16:58

I would have a look here:

Link

Forever learning
EGTB

Make sure to compare prices

PS Have you considered the effort of integrating new brakes compared to fixing what you have? It might be less effort to work with what you have. A very light tailwheel aircraft doesn’t actually need or want much braking power and I’ve found that people tend to throw away adequate lightweight brakes that could be overhauled and saved. Sometimes the reason is a shortage of parts or outrageous parts prices, but used parts can be found. I took this approach with a similar set of Cleveland (Van Sickle) cable operated mechanical brakes using some new parts and a few parts discarded by others who had changed to disks. I ended up with a very simple, lightweight set of original brakes that are fully capable of doing the job… and this was a certified plane.

Last Edited by Silvaire at 09 Nov 19:07

I’m afraid the brakes you mention there are all a bit expensive for me…

It’ll be a fair amount of work to fix what I have, the problem (and perhaps saving grace) being that they’re from an era when at least some parts can be handmade. I agree they’re probably powerful enough already. I guess there may still be advantages to be gained in how controllable they are, resistant to wet, overheating etc… I’ve never used drum brakes so I’m not in a position to know whether they’re good, bad or indifferent.

Have you figured out what make the existing brakes are? They’re built like stuff made for a lightweight aircraft, not adapted from something else. I think if you carefully overhaul what you have, they’ll work well enough. I found out that using modern linings can really make a big difference, versus glazed originals. The quality (smoothness) of the drum surface actually seems to make little difference as long as there’s not much runout. Up-sizing the axles to 1-1/4 inches might be a good idea.

I hope you can figure it out at reasonable cost. The Turbulent is such an wonderfully appealing design, with a great track record too. It does not need airliner brakes, all that will do is put you on your nose. Just enough to hold it for run-up and for differential steering.

No joy so far with the brakes.

The backing plates look handmade, and the drums are unmarked. I’ve split the wheels and they say ‘Made in England’ but nothing else. They’re 6" diameter, 4" wide.

Part of the problem is the mounting holes – as close as I can make out they’re 8mm diameter, 74mm between centers which I make as fitting on an 85mm diameter circle.

I’m still finding myself wondering whether it would be easier to simply put a disc brake on the wheel rather than refurbishing the drums I have. Not so much because I feel like spending money or need better brakes, but because I worry that if I ever find myself needing to replace a drum I’ll be back to square 1 and needing to rebuild the whole undercarriage again.

The frustration is that none of the standard scooter, mini-kart disc brakes or carriers seem to made to a 74mm bolt hold spacing. And though it’s possible to buy any number of different repco aircraft disc brakes none of them seem to give details of their dimensions… I suppose if you’re buying a brake for a C152 then all you need to know is that it will fit a 152. Fair enough.

Unless the drums are unserviceable now, I wouldn’t worry too much about replacing them in the future. I’ve seen more original drums on 60 year old aircraft than replacements, I think because their use in stopping a very light tailwheel plane is so minimal. Holding the plane for run up and turning the plane doesn’t wear the drums much and in practice that’s the major purpose of the brakes…

You could also machine drums out of solid if necessary.

if I ever find myself needing to replace a drum I’ll be back to square 1

Do not worry there. If you do the job more or less properly – in whatever way – the wheels will outlast many other components, and perhaps even yourself, or at least your flying career.

I can’t helping thinking that, if you can’t find parts that mate to what you have, then you replace more. Of course it is a shame to replace working parts, especially if you’re on a tight budget; but somewhere you’ll have to compromise between cost and speed and own effort. As a last resort, a complete mini-kart shouldn’t be too expensive and you could resell most of it, to begin with the engine. Couldn’t you hang around some mini-kart circuit, make some temporary friends and get pointed to a good source?

EBZH Kiewit, Belgium

There are low cost standard serviceable parts available at ACS. They are used on countless homebuilts. Hydraulic brakes from Sonex is an easy upgrade.

ENVA ENOP ENMO, Norway
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