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khorton01(at)rogers.com
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 Posted: Thu Apr 29, 2010 3:14 pm Post subject: Third Taxi Test Video (Brakes Over Heat!)... |
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Also, the RV-8(A) rudder pedals are quite different design that those
on other RVs. The pad where the foot presses on the rudder pedal is
well above the pivot point for the braking action, so if you press on
the rudder pedal you will apply some brake pressure - the geometry
guarantees this. I suspect that this design "feature" could
contribute to excess brake heating if you do a lot of taxiing, even if
you are careful to minimize the use of brakes.
Some folks have modified their RV-8 brake pedals to address this
concern. I am aware of two approaches:
1. Fabricate an extension to the foot pad, to extend it lower, such
that the bottom edge of the foot pad is below the pivot point for the
braking action. This allows you to push on the pad without applying
brake. If you want brake you tilt the foot forward to push on the
upper portion of the pad.
<http://www.romeolima.com/RV8/IdeasProducts.htm#IDEA:%20Rudder%20Pedal%20Extensions
>
2. Use one long bolt on each side for the brake pedal pivot, rather
than two short bolts. Push on the bolt shank to actuate the rudder
without getting brake. The bolt shank is a fair bit aft of the pad on
the top of the brake pedal, so you need a pretty good forward lean of
the foot to get max braking. The amount of lean forward of the foot
you need can be reduced by fastening something with some thickness to
the aft side of the foot pad.
Option 2 is the simplest, and is what I did to my aircraft. I found
that I did not need to build up the thickness of the foot pad, as my
feet were happy with the angle needed for max braking.
Kevin Horton
On 29 Apr 2010, at 06:58, Stucklen, Frederic W wrote:
| Quote: | Matt,
One other comment. Be sure that your brake pedals are not the
cause of the problem.
If the brake pedal hinge points have been over tightened, the result
will be that the
brakes will always drag. I've seen this on several RV's. The
solution is to pull all
the cotter keys on the brake pedals, loosen the castle nuts until
the joints rattle,
and re-install new cotter keys.
The internal spring on the master cylinders aren't very strong,
and any
binding of the peddle joints will result in the master cylinder
plunger not fully
returning to the relaxed position. This results in brake drag that
can turn your
disks cherry red... Your plane should taxi on tarmac with as little
as 900 RPM's. If
it doesn't, then your brakes are dragging�..
Fred Stucklen
RV-7A N924RV 365 Hrs Flying to Alaska in June
RV-6A N926RV 875 Hrs (Sold)
RV-6A N925RV 2008 Hrs (Sold)
--- On Wed, 4/28/10, Matt Dralle <dralle(at)matronics.com> wrote:
> From: Matt Dralle <dralle(at)matronics.com>
> Subject: Third Taxi Test Video (Brakes Over Heat!)...
> To: rv-list(at)matronics.com, rv8-list(at)matronics.com, rv7-list(at)matronics.com
> Date: Wednesday, April 28, 2010, 12:29 AM
>
> On the third taxi test, I headed out to the main runway at
> Livermore, 25R and ask the tower for a high-speed taxi test
> with no take off. It was approved as requested and
> went great. There was about a 15-20 knot head wind at
> about 270 which made it even more fun. The RV-8
> handled great and it was definitely ready to take off.
> I only got to about 1/3 power and it would have taken off
> with about 1/2 throttle probably. Oh my... What
> will FULL throttle be like!? Now that's exciting! Be
> sure to watch the Part 2 of this video because as the music
> gets more intense, so does the testing!
>
> Third Taxi Test - Part 1
>
> http://www.youtube.com/MattsRV8?v=pnz31m6aVEQ
>
>
> After the taxi back on the regular taxi way, the tower
> offered to let me run back the other direction on the
> runway! I wasn't sure that's really what he was
> suggesting and I had to verify that's what he really meant.
> It was pretty cool and saved a lot of time. With the 15-20
> knot tailwind, though, I probably would have been better off
> just using the taxi way. Now you'll notice the music is
> getting a bit more intense. Be sure to watch Part 3
> because that's where this taxi test REALLY get's
> interesting...
>
> Third Taxi Test - Part 2
>
> http://www.youtube.com/MattsRV8?v=5zheOkSHfX4
>
>
> As you'll see in that part of the third taxi test, I lost
> the brakes. As I'm taxing off the runway I noticed
> that there was smoke coming out of both the left and right
> sides. At the time, I really wasn't sure what caused
> the brakes to get so hot. But, after watching the
> video a couple of time and recalling back to what I was
> doing, I'm positive that I was dragging the brakes on those
> down-wind trips. I even remember thinking at one
> point, "oh, I'm riding the brakes". Doesn't seem like they
> should get so hot as to start smoking, but perhaps it was a
> combination of being new, over worked, and a bit of brake
> fluid leaking out and hitting the discs. Anyway, my comment
> at the end of the video is kind of funny. It wasn't at the
> time, mind you... 
>
> Third Taxi Test - Part 3
>
> http://www.youtube.com/MattsRV8?v=57W-O8905cg
>
>
> After I hosed the wheel pants and brakes down and got
> things cooled off and no longer smoking, I had to push the
> plane back to the hangar from the wash rack, which isn't too
> far, but still kind of a long ways at the end of a
> day. As I was pushing it back I noticed that there was
> brake fluid leaking out of the right brake. I pushed
> the plane about 1/2 the way into the hangar and took the
> wheel pants off. Once I got the leaks stopped, I
> pushed the plane the rest of the way in. It was kind
> of a demoralizing sight to see the brake calipers smoked
> like that, but it could have been a lot worse.
>
> A word to the wise - STAY OFF THE BRAKES!!! Its
> really easy to drag them and this video is a document to
> what can happen.
>
> Third Taxi Test - Epilogue
>
> http://www.youtube.com/MattsRV8?v=JlQjRWnbO2c
>
>
> The brakes were pretty toasted as were the sidewalls of the
> tires. There were little bits of rubber coming off the
> sidewall around the wheel. The brake pads definitely
> looked worn down some compared to the set I have on the
> partially completed RV-4. So in the interest of not
> holding up the test flight progress, I opted to use the
> wheels, brakes, and tires from the RV-4 project to replace
> the smoked components on the RV-8. I'll order a new
> set for the RV-4 later.
>
> I spent the day jacking up the plane and swapping
> pieces. I also took the opportunity to remove the
> right master cylinder and fix the pesky high-pressure side
> leak. Here's a video of the wheels, brakes, and tires
> all replaced and ready for testing.
>
> Third Taxi Test - Post Epilogue
>
> http://www.youtube.com/MattsRV8?v=dL92Hwi0xnE
>
>
>
> Matt Dralle
> RV-8 #82880 N998RV
> http://www.mattsrv8.com - Matt's RV-8 Construction Log
> http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV
> YouTube Channel
> Status: Test Flying
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Mark Phillips in TN
Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN
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pitts_pilot(at)bellsouth.
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| Posted: Sun May 02, 2010 3:32 pm Post subject: Third Taxi Test Video (Brakes Over Heat!)... |
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Bobby, thanks for that. MY phase 1 for my Pitts didn't have that
wording. I looked. Passengers during phase 1 (or the first flight
either) just weren't covered. But that was in a land long ago ......
Linn
Bobby Hester wrote:
| Quote: | The wordage is in your Operating Limitations for Phase I, this is for
the whole Phase I period.
I sure you could find it somewhere on the FAA site also. See attach jpg
----
Surfing the web from Hopkinsville, KY
Check out the latest on my website at:
http://home.newwavecomm.net/bobbyhester/RVSite.htm
Linn Walters wrote:
>
>
> I was under the impression that the single person requirement was only
> for the first flight. I hope someone will set me straight.
> Linn
>
> Greg wrote:
>>
>>
>> The dual is in a different RV-8 I hope. The feds have made it crystal
>> clear
>> that there are no circumstances where more than one person can be in
>> an RV
>> during Phase 1.
>>> looking forward to that. But I'll have a lot of dual before I'm off
>>> on my own.
>>>
>>
>>
>>
>>
>>
>>
>
------------------------------------------------------------------------
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