Brakes ....any way to improve them?

Love this web site. Just started flying off my 40 hours. Up to 11 hours!!!! My question is the breaks on my RV7a.... I know I have a few air bubbles in the line. Have had trouble bleeding them, but they work. Just not too impressed with the stopping performance. Is it me, or a few bubbles in the line that just doesn't seam to want to stop as well as my old Piper cherokee. Is there a modification that would improve the performance. My breaks hold on run up, but that's not where I miss good breaks. Have not had any situation that needed a quick breaking, but I don't think I could do it in an emergency! I would appreciate any experiance or Ideas. I'm not against replacing them if there could be significant improvement. I'm sorry, but it's a safety issue to me and I don't put a price on that! Thanks in advance for any replys.
Bill

Spelling

Last time I checked the binders on my plane were called brakes. Bubbles will affect brake performance so you need to loose them. Get someone to help who has experience in brake bleeding. Energy management is also key in braking. Learn to land slower and rely less on the brakes. For emergencies, get the air out.

Loose?

zilik said:

Last time I checked the binders on my plane were called brakes. Bubbles will affect brake performance so you need to loose them. .....

Click to expand...

I think you mean "lose". [What goes around, ................]
Sorry, couldn't resist!

Did you condition the brakes before you started to use them. Get the air out of them. Any RV that I have built you could nose the plane over if you stood on them.

If you really want to nose the plane over, I've heard Grove brakes bring the heavy glasair III's to a grinding halt very quickly...

If you are still concerned about the stopping performance after bleeding properly, from the bottom to the top, then you can fit thicker discs and different calipers - its not cheap. I know its a mod available from Cleavland for the Extra 300 that use 5" wheels, can't see why you couldn't fit the same parts to your RV. But, I would suggest you bleed the lines and make sure you properly bedded in the pads (requires a couple of hard stops from taxi speed, but check the instructions) before doing anything more drastic.

Pete

Yep

zilik said:

Learn to land slower and rely less on the brakes. For emergencies, get the air out.

Click to expand...

.....you really can land and stop in under 1000'. I show students that all the time in my -6A with Van's wheels and brakes.

Regards,

My 160 HP RV-6 has has been flying over 2,100 hour over the past 10-years. IF I stop, go to full power, the brakes / tires are locked up and the plane is moving forward. Yes there is enough power to pull the airplane forward with locked brakes skidding the tires. More powerful brakes are not going to hold the airplane in place. The airplane can land in the distance that Van's advertises IF you slow the airplane down before you touch down.

Try pressure bleeding them from the calipers up, not gravity bleeding. Works every time for me, bubble free, I can stop on a dime. (a very large dime)

Thanks

Ok, I get the message. I'm working on the short field landing, but usually let it roll out, saving the brakes. Just tried to do some hard braking and it didn't seam right. I will do the bottom up bleeding and get the air out and compare. If it doesn't do the trick, I'll check out the other brakes.
Thanks again guys! Sure wish I found this board earlier while I was building it!
Bill

You may need to refine procedure

I had a Piper Archer II for 22 years and flew it twice a day every work day for 15 of those years. I have about 450 hours on my RV-6A and feel very comfortable with it but there are some sensitivities I have had to develop in the transition between the planes. The bubbles can be overcome in operation but there has to be compression of the air when you apply the brakes with the system in that condition. If you don't want the spongy feeling you neet to bleed them from the bottom back up through the reservoir. A probblem exists when the Cleveland master cylinder springs do not return the piston all the way to the full off position and return to the reservoir port is not open - I had to stretch my springs. Manufacturing defects can occur and I had one in a new Cleveland master cylinder when first used in my RV-6A. In my case the o-ring on the piston was scalloped (cut) during manufacturing assembly of the piston into the cylinder. This provided a leak path past the piston into the upper part of the cilinder for fluid and air. An overhaul kit for the master cylinder (new o-ring) fixed that problem. The RV is short winged and fast and it is very important to land on the mains as always but trim for slower flight (nose up) and hold the nose off forever when landing. With the Archer I developed a very bad habit of relaxing the back pressure and letting the nose settle on as soon as the mains were running smooth and I would get on the brakes bring it to a fast stop for quick turn-off occassionally at taxiway K off of 19R at the John Wayne Airport in Santa Ana, CA. With the big hydraulic strut this was no problem but it is a very bad idea on an "A" model RV with the springy tapered rod strut. No doubt you have read of the failures in the field and it is my personal opinion that these are caused by imperfect or careless operating procedures. You are in for a shock when your nose gear pivot breakout force gets below the required value and the nose wheel goes into the death rattle shimmy the first time. This is another thing you have to stay on top of and continue chacking and tightening as required until it gets well settled in an no longer deminishes. As you takeoff and apply right rudder you will have a tendency to apply the right brake and it will wear out fairly quickly. When I do my annual I replace the pads whether they need it or not. When you are stopped on the ramp and one brake is gone in and "A" model you cannot assume that with your superior aviator skills you can taxi and fly the plane with one brake and finesse your way through it. When nose wheel pivots to one side in response to the good brake you are powerless to bring it back with rudder only at slow speeds (a taxi out of a parking spot can easily result in a collision with the adjacent airplane).
Summary:

- Get the air out of the lines
- Be aware that your new hardware may not be perfect and fix problems
- Consider the nose gear something to keep the prop from hitting the ground during slow taxi operations and never let it touch the ground when you can help it. PANIC STOPS SHOULD BE RESERVED FOR REAL EMERGENCIES
- Check the breakout force and keep it right
- Do not try to operate with a failed brake

Bob Axsom

RV6_flyer said:

My 160 HP RV-6 has has been flying over 2,100 hour over the past 10-years. IF I stop, go to full power, the brakes / tires are locked up and the plane is moving forward. Yes there is enough power to pull the airplane forward with locked brakes skidding the tires. More powerful brakes are not going to hold the airplane in place. The airplane can land in the distance that Van's advertises IF you slow the airplane down before you touch down.

Click to expand...

I agree with Gary
An RV with properly operating brakes should be able to skid the tires. With a constant speed prop you can slide the tires on pavement during a full power runup (even an RV-10)
Besides getting the system bled properly, another cause of poor braking performance can be improperly conditioned brake pads.

As already mentioned, short landings start with a touchdown where the stick is full back in your lap. The ultimate short landing (takes LOTS of practice) is with an approach at minimal airspeed so that the roundout, flair, and touchdown all occure with one continous smooth movement of the stick taking probably five seconds or so with a touch down occuring at the moment you hit the full up elevator stop. This takes lots of practice and should be approached progressively . You must get very familiar with the airplane and the field of view in the landing flair to where it is second nature. It takes a lot of practice to learn to nail the required approach speed factored against the current airplane weight at the time of the landing.

Good pilot procedure aside......

The standard Clevelands supplied by Vans have more than enough power to hold a run-up. However, static use is not the issue. The concern is kinetic energy rating.

We're supplied with 40-78B/30-9 sets yes? Kinetic energy rating is only 117,500 ft-lbs. Installing a 199-93 upgrade kit pushes the kinetic energy rating up to 155,000 ft-lbs. The kit is a thicker brake disk (and the necessary hardware). The thicker disk stores more energy for later dissipation. The inability to store enough energy results in overheated components, brake fade and failed caliper seals.

The Brake Kinetic Energy equation (from Part 23.735) is:

KE = (.0443*W*V^2)/2,

where:

KE is Kinetic Energy in foot pounds (ft. lbs.)

W is aircraft Weight in pounds (lbs.)

V is the aircraft's speed in knots (KIAS) squared

2 = number of brakes

Assume an RV7A/8A at a gross weight of 1800 lbs aborting a takeoff from 50 knots (rated stall at gross):

KE = (.0443 x 1800 x 50^2)/2 = 99,675 ft-lbs

The above equation assumes you started with cold disks. Any A-model probably arrived at the runup pad with warm-to-hot disks, depending on pilot technique, distance, taxi path, and wind. With hot disks, braking will be marginal; your whole available rating was 117,500.

Re-run the equation and you'll find an abort from 55 knots exceeds available brake capacity (120,606) even starting with cold disks.

Now assume a landing weight of 1550 lbs and commence braking at 50 knots:

KE = (.0443 x 1550 x 50^2)/2 = 85,831 ft-lbs

The above might be typical for arrival at a busy fly-in, and can be followed by 15 minutes of stop-go-steer in the taxi conga line. There is very little capacity remaining and the brakes don't dissipate heat well inside tight wheelpants. It is not unusual for an RV-A to arrive at a parking spot with hot, mushy brakes.

The tailwheel models have a big brake advantage; they don't heat the brakes to steer. In my opinion, A-models should get the upgrade. Your opinion may vary, and yes, obviously pilot technique is a factor.

All the ratings and part numbers are found on Cleveland Drawing 50-76

DanH said:

Good pilot procedure aside......

The tailwheel models have a big brake advantage; they don't heat the brakes to steer. In my opinion, A-models should get the upgrade. Your opinion may vary, and yes, obviously pilot technique is a factor.

Click to expand...

Pilot tech. is a big factor. I can taxi all over an airport with an "A" model and hardly use the brakes (unless there is a strong cross wind). Many "A" model pilots seem to have to use the brakes constantly.

Scott is right...

You'll be surprised at how effective the rudder is. Try it, you'll like it.

Those little brakes are up to the task of what you need to assist with directional control and slowing the aircraft from a taxi to stop. I do not use them for aggressive deceleration. If you do a surprise failure of one side can cause a big problem; Overheating can lead to brake fire; Tire wear goes up; Pad/disc wear goes up. I don't want bigger, read heavier, more expensive brakes. Operate the aircraft to the maximum extent possible in a way such that an unexpected brake failure would be a non event.

Get the bubbles out.

Other than that,

Land slow,

Let it roll man,

Let it roll.

As mentioned by several others;
1. Get the air bubbles out
2. Go thru the brake conditioning routine.
You should have great brakes after that.
Danny

DIY brake upgrade

DanH said:

Good pilot procedure aside......

The standard Clevelands supplied by Vans have more than enough power to hold a run-up. However, static use is not the issue. The concern is kinetic energy rating.

We're supplied with 40-78B/30-9 sets yes? Kinetic energy rating is only 117,500 ft-lbs. Installing a 199-93 upgrade kit pushes the kinetic energy rating up to 155,000 ft-lbs. The kit is a thicker brake disk (and the necessary hardware). The thicker disk stores more energy for later dissipation. The inability to store enough energy results in overheated components, brake fade and failed caliper seals.
snipped

Click to expand...

The 199-093 upgrade kits are available from both ACS and Wicks for about $600. However, I can suggest a way to make your own for less. The Cleaveland kit contains thicker rotors (approx 0.300" vs .188"), 2 spacers to be placed between the halves of your brake calipers, longer bolts for the calipers, thin flat washers for the bolts and new brake linings.
Long Eze's come with a heavier duty set of Cleaveland brakes. They use 5:00 X 5 wheels (same as ours), thicker rotors (.375" thick) and larger calipers (2" pistons vs our 1.5")
Lots of the Long Eze builders had trouble with these brakes (owing more to very close shrouding of the wheels by the wheel pants). Many builders purchased Matco or Grove wheel/brake set ups. See if you can purchase a used set of these .375" thick rotors. I found a new pair which had gotten rusty laying in the box on EBay cheap. Try posting a WTB ad on

http://groups.yahoo.com/group/canard-aviators/

I'll bet you find more than one seller. Resurface the rotors to a thickness of
.312". Break your calipers apart. Fabricate two shims out of 1/8" thick 6061-T6 aluminum to allow the thicker rotors to fit your calipers. Purchase 4 bolts 1/8" longer than stock and fit it together. I did this and it cost me about $60 (I was able to do the rotor machining myself)
Charlie Kuss

DanH said:

Good pilot procedure aside......

The standard Clevelands supplied by Vans have more than enough power to hold a run-up. However, static use is not the issue. The concern is kinetic energy rating.
snipped
The above equation assumes you started with cold disks. Any A-model probably arrived at the runup pad with warm-to-hot disks, depending on pilot technique, distance, taxi path, and wind. With hot disks, braking will be marginal; your whole available rating was 117,500.

Re-run the equation and you'll find an abort from 55 knots exceeds available brake capacity (120,606) even starting with cold disks.

Now assume a landing weight of 1550 lbs and commence braking at 50 knots:

KE = (.0443 x 1550 x 50^2)/2 = 85,831 ft-lbs

The above might be typical for arrival at a busy fly-in, and can be followed by 15 minutes of stop-go-steer in the taxi conga line. There is very little capacity remaining and the brakes don't dissipate heat well inside tight wheelpants. It is not unusual for an RV-A to arrive at a parking spot with hot, mushy brakes.

The tailwheel models have a big brake advantage; they don't heat the brakes to steer. In my opinion, A-models should get the upgrade. Your opinion may vary, and yes, obviously pilot technique is a factor.

All the ratings and part numbers are found on Cleveland Drawing 50-76

Click to expand...

I'm with you Dan. You forgot to tell them that our brakes were intended for 1500 pound max gross weight vehicles. They were first used on RV-3s and RV-4s, which are within the designed weight. The newer 7As and 8As have 1800 pound gross weight limits. Don't believe me. Look it all up on Cleaveland's web site. I did!
Charlie Kuss

DIY caliper shims

Listers,
I just thought I would add a photo of how my caliper looks with the shim I installed to allow the use of thicker brake rotors.
Charlie

I land my 7 in about 500 feet without standing on brakes. Three point full stall, I do have a constant speed prop, but slow it down. As others have said, get the bubbles out, push fluid up from bottom.

I'm with Dan on this issue regarding brake sizing. Proper technique will prevent you from abusing your brakes unnecessarily. For normal use, the brakes are fine. No point to adding two pounds [added weight of the thicker rotors] if you don't need them.
However, for folks who have to deal with short landing strips and other less than ideal situations, upgrading to thicker rotors may make sense. I was PMed by another lister regarding where to find info on Cleveland's various wheel and brake products. I found the link below. You can download the Owner's maintenance manual, the Technician's [mechanic] maintenance manual and the product catalog from the links below. See

https://www.parker.com/literature/Aircraft%20Wheel%20&%20Brake%20Division/AWB%20Static%20Files%20for%20Literature/AWBTSG0001.pdf

The Technicians Service Guide linked above was updated last year [2021]

and

https://www.parker.com/literature/Aircraft%20Wheel%20&%20Brake%20Division/AWB%20Static%20Files%20for%20Literature/AWB%20Product%20Catalog%20Static%20Files/AWBCMM0001-12.pdf

The Component Maintenance Manual linked above has also been updated

https://www.parker.com/portal/site/PARKER/menuitem.223a4a3cce02eb6315731910237ad1ca/?vgnextoid=0ed66d8a0465e210VgnVCM10000048021dacRCRD&vgnextfmt=EN

Cleveland Wheel & Brake Home Page



Charlie

For maximum braking, raise the flaps as soon as you land. So long as the plane is generating any lift, maximum braking is reduced due to limited pressure on the mains.

Of course, it really doesn't make as much difference with the slow landing speed of the RVs - but on those glass planes it can be quite noticeable.

If you REALLY need to stop quickly, a drag chute like the F-4s carried would help...

chaskuss said:

http://groups.yahoo.com/group/canard-aviators/

I'll bet you find more than one seller. Resurface the rotors to a thickness of
.312". Break your calipers apart. Fabricate two shims out of 1/8" thick 6061-T6 aluminum to allow the thicker rotors to fit your calipers. Purchase 4 bolts 1/8" longer than stock and fit it together. I did this and it cost me about $60 (I was able to do the rotor machining myself)
Charlie Kuss

Click to expand...

Maybe I missed something, but will the 2in. piston calipers fit the backing plate that's already on a Van's aircraft????

More than you ever wanted to know about Cleveland brakes

mannanj said:

Maybe I missed something, but will the 2in. piston calipers fit the backing plate that's already on a Van's aircraft????

Click to expand...

Mannan,
I'm sorry if I've caused any confusion. The brake upgrade I was referring to is only an increase in brake rotor thickness. The thicker rotor can absorb more heat before the brakes will fade. Stock rotors are .187" thick. The Cleveland part number for the stock RV wheel/brake combo [RV3 thru RV9] is 199-102 See

http://www.aircraftspruce.com/catalog/lgpages/cleve_homebuiltwb.php

Cleveland offers an "upgrade" kit, which raises the kinetic energy rating of the stock 199-102 brakes. Both ACS and Wicks carry this kit in their catalogs. The upgrade kit is 199-093. See

http://www.aircraftspruce.com/catalog/lgpages/cleve_heavydutywb.php

It consists of thicker [.300"] rotors, new pad linings and rivet kit, 2 spacers for the stock [1.5" diameter piston] calipers [30-09] and new hardware to allow the use of the spacers. The spacers are needed so that you can fit the thicker rotors inside of your calipers.
IF you are interested in this upgrade kit, you can save some money [quite a bit] by simply buying the thicker rotors [part number 164-09900], making your own spacers and buying four 1/8" longer bolts [to hold the caliper halves together]. Cleveland prices the caliper shims at about $85 each! That's fairly steep for something you can make yourself in about 15 minutes.
The 2" calipers [30-133]are gross overkill for any RV, except for an RV10. They are used on the Cleveland wheel/brake kit model 199-152. See

https://www.aircraftspruce.com/catalog/pnpages/199-152.php

This wheel/brake kit is used on Harmon Rocket, Long Eze and Cozy aircraft. The wheels are the same, but the rotors are even thicker [.370"] and feature the larger calipers.
Someone is currently selling one of these 199-152 kits in the classified section. I purchased a 199-152 kit years ago. The seller misrepresented what he had. I was looking for a 199-156 kit at the time. Adding the 199-093 upgrade kit to the stock 199-102 parts that Vans supplies essentially converts them to the model 199-156 specification. The 199-156 kits were used on the VariEze. See

https://www.aircraftspruce.com/catalog/pnpages/199-156.php

I "think" that the 2" calipers [30-133] use the same mount as the 1.5" [30-09] calipers use. I may be wrong about that, as it's been a number of years.
Consider just using the stock brakes. You can always upgrade them later, if needed.
Charlie

mannanj said:

Maybe I missed something, but will the 2in. piston calipers fit the backing plate that's already on a Van's aircraft????

Click to expand...

Mannan,
After reviewing the thread, it was Pete [Penguin] who mentioned the 2" calipers. He didn't mention a part number for the upgrade kit he was referring to. That kit was for the Extra 300. I suspect the kit he refers to comes with the .370" thick rotors and larger 2" piston calipers. Installing those parts would bring the brakes up to the 199-152 kit's specifications. I can tell you that it would add a LOT of weight and would be going overboard.
To determine if the caliper mounts are the same, check the mount's part number for both the 199-102 kit [stock] and the 199-152 kit.
Charlie

Sorry if this offends anyone but, I've noticed that MOST people recommending upgrades over stock kit components don't have a finished airplane in their signature. Stock brakes WILL LOCK THE WHEEELS, both on landing and for takeoff. What more do people want?, and yes I understand all about "brake energy" charts from my airline flying and rejected takeoff and subsequent takeoff time limits.
The only thing I can see improving stopping performance on an RV is an anti-skid system, and I can't believe nobody has asked why Van's doesn't offer one of those.
Improperly conditioned pads are probably the culprit of poor brake effectiveness.
Regards,

I agree with Jon. The stock brakes on my -4 scare me sometimes they work so well. I have shaky gear legs as I slow through certain speeds so 9 times out of 10 I'm on the brakes hard just before the top end of shaky-gear-leg-speed. I can lock the tires very easily. What more do you need?

breister said:

For maximum braking, raise the flaps as soon as you land. So long as the plane is generating any lift, maximum braking is reduced due to limited pressure on the mains.

Click to expand...

I would think keeping the flaps extended would be more drag helping the plane to stop. JMHO.

Yes, they do.

mannanj said:

Maybe I missed something, but will the 2in. piston calipers fit the backing plate that's already on a Van's aircraft????

Click to expand...

Mannan,
I just checked the Cleveland Product Catalog. Both the 30-09 [stock] and 30-133 [2" piston] calipers are mounted with the same 075-00800 torque plate assembly [aka mounting bracket].
Charlie

I switched to Grove...

I most often fly 2 up with lots of gas (we do a lot of xc) and I wanted better brakes just in case an aborted TO was ever required. This is where maximum braking power will be required, not landing like most folks are mentioning. Although a side benefit can be shorter landings the real benefit will be if you ever need to stop quick on an aborted TO at gross weight

Just as a side note, before I became aware the "fragility" of the nose gear I abused the heck out of it, maximum braking stops on both paved and rough sod strips without a problem.. I treat it a little more gingerly these days thanks to this forum but I also know it can take more abuse than most folks give it credit for, either that or I was just lucky

It really takes practice to get the landing speed down where it belongs, very easy to keep the speed to high as you get acustomed to flying fast, that makes the slow landing speed seems unnatural without slow speed practice (which I do when the wife is not with me)

Geico266 said:

I would think keeping the flaps extended would be more drag helping the plane to stop. JMHO.

Click to expand...

As speed diminishes, rolling drag becomes more effective than wind drag. By retracting flaps, more weight is placed on the tires making rolling drag and braking more efficient.

Brakes

chaskuss said:

Mannan,
I just checked the Cleveland Product Catalog. Both the 30-09 [stock] and 30-133 [2" piston] calipers are mounted with the same 075-00800 torque plate assembly [aka mounting bracket].
Charlie

Click to expand...

Thanks! You guys are awsome!

I was just going through "what if's" in my mind when I posted. I use the brakes very little on my -8. Mostly for runups and to make the turn off if I'm a little fast at touch down.

Taking out the flap also unloads the nosewheel.

nucleus said:

Taking out the flap also unloads the nosewheel.

Click to expand...

And, once below flying airspeed, the stick all the way back will help transfer more weight to the mains as well, making the brakes more effective.