Hangar Flying => Hangar Flying => Topic started by: Lowlevldevl on July 04, 2006, 04:46:36 PM
Title: Brakes and Rudders Question
Post by: Lowlevldevl on July 04, 2006, 04:46:36 PM
Hi All, I am a new Long-EZ owner (non-builder) and feel that my brakes (Cleveland) don't have the stopping power my aircraft needs. I'm very close to ordering a set of either Matco or Groves with around the 300,000 KE rating. An aborted take-off and a scary ride to the end of the runway prompted this decision. My aircraft also has the old stlye small rudders. Doing some crosswind take-offs the other day I noticed that I was using a fair amount of brake to hold the thing straight. My questions then are: (1) Will I be constantly locking brakes and scrubbing/smoking tyres during crosswind take-offs with the new brakes? (2) Is it possible, if so how big a job is it, to modify the vertical stabilizers to the newer, larger rudders? And will that make a noticeable difference to crosswind ground handling control? I look forward to your wise counsel. Cheers, Don
Title: Brakes and Rudders Question
Post by: Drew on July 04, 2006, 06:11:25 PM
You can change to the Matco---but my guess is that is not your problem. You have something else wrong with your brakes. You most likely have one of these problems: -No brake fluid/leaky brake fluid -Worn pads (lots of brake travel with little stopping action) -Air in the lines---need to bleed them (spongy feeling brakes) -brake lines with too small of an inner diameter (needs lots of brake pressure to activate brakes---feels like you really have to stomp on them)
For the rudders. check the manual to see what the max deflection of the rudder is with max brakes (you measure it with a ruler instead of some sort of angle gauge---so an easy task with very common tools. If you are not getting max deflection prior to max brakes, you won't have enough rudder (which sounds like it is your case).
For take off runs, don't ride the brake. You should be "tapping" the brake---but you need to let the plane accelerate----read the crosswind techniques in the owners manual.
As I said---from your description---something is wrong with your brakes----and I don't think you are getting full swing on the rudders.
Title: Brakes and Rudders Question
Post by: Waiter on July 05, 2006, 08:36:36 AM
Out of my 3,000 hours of canard time, maybe 5 of it was with the older short rudders. I'll be honest with you, I really didn't notice any difference, I wasn't specifically evaluating the short vs long rudders, these were first flights.
I think if the rudders/brakes are adjusted properly, you won't notice any differences at the slower speeds. I found the "feel" transition from rudder to brake and vice versa seemed identical to the long rudders. (Again, I wasn't specifically looking at this, but I didn't notice anything unusual)
Brakes seem to be the number one maintenance issue on my LongEZ, I have the original light duty Clevelands. I go through a set of pads every 150 - 250 hours. I also found that I need to replace the "o" ring in the caliper every 2nd or third set of pads. I think caliper heat and high braking pressure prematurly flattens out the O-ring.
I also find that about every 1200 - 1500 hours, I need to replace the disk, It starts to develope a slight curvature (like concave) and doesn't allow the pads to wear evenly.
As for the "soft brakes"
If the brakes are not properly heat treated, they will fade out very quickly. You'll be lucky if they can disipate enough energy to stop you even at a moderate taki speed.
Make sure the brake pads have been properly broken in i.e. heat treated. I usually start at slow speed taxi and drag the brakes until I can start to feel them fading, I continue taxi with no application of the brakes to allow then to cool.
I then move to the runway and increase the speed to about 30 - 40 kts, From the start to the end, I can get two or three very aggressive full stops on the entire length of the runway. I taxi back to allow the brakes to cool.
One more high speed taxi down the runway at about 60 kts and two or three full aggressive stops usually finishes the job.
The brakes should now be fully heat treated and you'll find they are very firm, and you should be able to lock up the tires.
Waiter
Title: Brakes and Rudders Question
Post by: Lowlevldevl on July 05, 2006, 04:17:01 PM
Thanks for the advice fellas. Sounds like it might be an idea to simply replace the discs and pads and try again. However, I've read a few articles on-line which suggest that a 0-320 Long typically loaded with full fuel and the landing speeds of the Roncz canard needs a lot more than the 117,000 KE rating of the standard Cleveland brakes. I guess I'd like to know has anybody here had the experience that you can have too much brake. Some of the fields I'd like to fly into are a little on the short side and I don't really feel that I want the experience of re-building a melted gear leg.
Title: Brakes and Rudders Question
Post by: Drew on July 05, 2006, 04:48:08 PM
The real high stress for the brakes is the aborted takeoff---very high speed, not much runway left, and max brakes. During "normal" landings, you usually don't need to apply brakes right away (even on short runways). For the KE equation, pay attention to the speed you are giving it---the speed is a square term where the mass is not.
A brake disk that absorbs more KE puts out more heat----so the better brakes have a better chance of melting your gear. If you have heat shields on the gear along with fiber frax, you should not have any problems regardless. I have only heard about people melting gear legs when they had no shields.
Title: Gear heat shields
Post by: Gilbert DRIEUX on July 06, 2006, 12:30:11 AM
VariEze with LE gear.
Where to find description and/or material for gear heat shields ? Until now, I don't have problem, but I'm interested to plan this mod.
Regards to you all.
Title: Brakes and Rudders Question
Post by: Drew on July 06, 2006, 03:37:46 PM
heat shields are described in the canard pusher. The CPs contain all the mandatory changes to the Rutan plans.
You can go to just about any builder site and look up the chapter that talks about brakes. Generally, you are bolting a piece of aluminum between the axel and the strut. The 4 axel bolts go thru the axel, the shield and the strut. The shield physically blocks the radiant heat from the brake disk to the strut. You can't let the disk "see" the strut----or you will melt it----eventually.
Title: Brakes and Rudders Question
Post by: Gilbert DRIEUX on July 06, 2006, 04:45:46 PM
Ok Drew. Thank you for this clear explaination. I'll read the CP and builders site. Simple <<don't to let the disque "see" the strut....>>
Regards,
Title: Brakes and Rudders Question
Post by: Drew on July 07, 2006, 07:18:49 AM
It helps if you have the CPs with pictures---a picture is much clearer than an explanation.
This site: http://www.cozybuilders.org/ref_info/
has the CPs---but text only.
Searching this document shows that the heat shield info is in CP 57 and 70.
Title: Brakes and Rudders Question
Post by: Waiter on July 07, 2006, 07:53:48 AM
I wrote a description somewhere! (here or on one of the other forums), I think it was related on how I installed my wheel pants. Part of the wheel pant installation was a heat shield. The heat shield was made out of .125 aluminum and was installed between the axel and the bow. The shield was round about 1/2 inch larger in diameter than the brake disk. It had a cutout for about 1/4 inch clearence of the brake caliper and brake line.
The shield also acted as the mount for the wheel pant.
I'll see if I can find any photos.
Waiter
Title: Brakes
Post by: easyrider on July 07, 2006, 01:41:06 PM
I changed to Grove brakes after I had a Cleveland caliper crack and leak. A new Cleveland Cylinder complete was $302. A Grove 500x5 wheel and brake set was $494 for a pair. You do the math, I bought the next set up the high performance with dual piston calipers, best mod. I have ever done to the LongEZ. There is still the problem of Nyla-Flow/Nyla- seal brake lines. Nylon eventually age/heat hardens and the lines to the calipers will fail. I have made up a Srataflex mod. kit to replace the nylon lines to the brakes cylinders without having to modify the gear legs. Send me an E-Mail and I will send pictures and details of kit Easyrider LongEZ93EZ
Title: brakes
Post by: eric r on July 07, 2006, 07:02:51 PM
I'll be adding gear leg fairings soon. Should I just add Big-A stainless steel brake lines while I add the fairings? Seems logical. What size lines are best? can they be too big?
Title: Brakes and Rudders Question
Post by: Drew on July 07, 2006, 08:14:23 PM
Go with the inner diameter as called out in the plans. If you use less diameter, you will have to stomp way too hard on the brakes to get them to work---unfortunately, I have experience here.
If you use a stratoflex braided type brake line and go one inner diameter size larger, the brake caliper won't float properly and the brakeline will drag---unfortunately, I have experience here too. The stratoflex type of line of the proper inner diameter works just fine.
I would not do the hard-line.
If you keep the brake lines protected behind the shield, they should be fine.
You can make things fairly easy by putting a fitting near (or in) the hell hole for the brake lines to make them easy for change out. I currently run slightly larger stratoflex from the cylinders to the hell hole, then run nyloflow down the gear legs. If you are wondering why this strange combination, go re-read the first couple of paragraphs.