Wednesday, June 21 2006 @ 09:12 PM EDT Contributed by: Kevin Horton Views: 1505
I saw a thread on the VAF WWW forums awhile ago about a clearance problem between wheel pants and brake calipers. I put an item on my To Do list to check this. I've been working on the final wheel pant tweaking lately, so yesterday I finally screwed up the courage to take a look at this on the left wheel pant. Sure enough, the back bottom corner of the brake caliper was hitting the wheel pant. This would push the floating caliper towards the brake disk, causing a dragging brake. At best, this would only lead to excessive brake wear. At worst it could lead to overheating brakes and a brake fire, or a control problem on the ground.
Some guys said they fixed the problem by putting a bulge in the wheel pant in this area. That would certainly work, but the thought of even more fibreglas work turned my stomach. Some other people reported that they fixed the problem by bending the wheel pant attachment bracket to push the bottom part of the wheel pant inboard, away from the brake caliper. I decided to try this.
I spent two hours tonight bending the bracket a bit, then putting the wheel pants on (one hard to get at bolt on the axle, plus a whole bunch of screws), using a flashlight and mirror to check the clearance, only to see that the wheel pant still hit the caliper, taking the wheel pant off, and then repeating the process. I finally got just the right bend on the bracket so I have about 0.050 inch clearance (as judged by a finally calibrated eyeball).
My back is very tired after two hours on my knees, bent over that wheel pant, so I am having a very tasty beer.
Update - 22 Jun 06 - I checked the right wheel pant this evening, and it too was hitting the brake caliper. I tweaked the attachment bracket to solve the problem. It went a lot quicker than last night, as I had learned a few things.
The big lesson is to be careful to keep the same angle on the flat part of the bracket that the wheel pant mates up to. Last night, I started off only bending the bracket right where it comes off the landing gear leg. This moved the end of the bracket inboard, which is what I wanted, but it also changed the angle on the end of the bracket. Then, everything would look OK until I tightened the screws that held the wheel pant to the bracket. As soon as I tightened the screws, the wheel pant would deform and hit the brake caliper. I finally figured out that I needed to bend the bracket in two places - at the landing gear leg, and at the flat part where the wheel pant attaches. The bracket needs to be parallel to the wheel pant surface, so that the wheel pant doesn't deform when you tighten the screws.
Tuesday, May 23 2006 @ 06:14 AM EDT Contributed by: Kevin Horton Views: 2201
I got back on Friday from two weeks in Brazil. Great trip, but it looks like this is the last one, as we closed off all the outstanding items on the Embraer ERJ 170/175/190 projects.
While we were in Brazil, I visited Gilberto Cardoso's RV-7 project. Gilberto previously built a One Design (wooden single seat aerobatic monoplane), but decided that the RV-7 is a better match to his needs.
Gilberto showed us Joseph Kovacs K-55 project. Mr. Kovacs was the chief designer for Embraer for many, many years. He was responsible for many aircraft, including the Brasilia, Tucano, AMX and ERJ-145. After retirement, he designed the two seat K-51, which looked like a small taildragger Tucano.
We met Joseph Kovacs, and saw the K-51 on my very first trip to Brazil, in 1999.
Now he is working on the K-55, which will be a single seat unlimited aerobatic monoplane, with an unusual flight control system. The inboard and outboard ailerons also move when the stick is move fore and aft. If you pull the stick aft, the ailerons deflect down, to increase the wing's lift.
This weekend I did a couple of rounds of fill, sand and prime on the wheel pants, upper landing gear leg intersection fairings and the spinner.
I'm heading back on the road today, getting back Thursday night. Oh well.
Tuesday, April 18 2006 @ 09:10 PM EDT Contributed by: Kevin Horton Views: 1051
I've been slowly grinding away at the snag list, and doing a bit of fibreglas work. The snag list is down to 50 or so, plus bunch of To Do items.
Some days go well, but other days are a struggle to make any real progress. The flexible hoses are a good example. I got them pressure tested a few weeks ago, and then ordered the band clamps and clamp tightening tool I needed to put the firesleeve on. That stuff arrived on Thursday. Saturday I put the firesleeve on several hoses, and finished the ends of the sleeve with some red high temperature RTV silicone. Sunday I grabbed the first hose, to put it back on the aircraft. The hose I grabbed was part of the inverted oil system, and went from the front left corner of the oil sump, around the front of the engine, to the inverted oil system tank behind the engine on the right side. The additional diameter from the firesleeve meant that the hose didn't fit around some of the corners the same way, and I had a very tough time getting it hooked up - it wasn't quite long enough. I eventually had to rework the position of the inverted oil tank a bit to move it closer to the engine. It took about an hour.
Then I realized that I should inspect the inside of the hoses to be sure they were clean. They were clean before they were pressure tested, but I hadn't looked inside since. I grabbed a hose, held it up to the light and looked inside - it wasn't clean - it looked like there was some very fine grit. I looked at some more hoses - same thing. So, I removed the hose I had installed, and spent quite a while pulling some clean rags through the hoses with a piece of nylon cord to clean them. Monday I finally got that first hose back on, but I still have some work to do to properly secure the inverted oil system tank in its new position.
Sunday, April 09 2006 @ 08:26 PM EDT Contributed by: Kevin Horton Views: 921
We spent the last several days of this week in Toronto, as Terry had a convention to attend. It made a nice break from Ottawa. The hard drive in my laptop died the night before we left, so there was a big panic the next morning to purchase a replacement hard drive, and perform the surgery to replace it. The old hard drive had been making strange noises for awhile, so I was expecting it to fail at some point, and had been making daily backups. So I didn't lose anything of importance, just a few hours time.
I've been slowly working down the list of snags. But I'm adding new ones to the list about as fast as I cross old ones off. It has finally warmed up a bit, so I've also done a few rounds of fill and sand on the various fibreglas parts.
The last really big job I need to do before taking the aircraft to the paint shop (other than finishing the fibreglas) is making the top for the engine cooling air plenum chamber. I've been putting off starting on this, as I hadn't figured out how I was going to seal the front of the plenum chamber to the cowling. You need a good seal there, or a bunch of the high pressure air that comes in the inlets won't actually be used to cool the engine. You incur a drag penalty for each bit of air that comes in the inlets, so if you want the maximum performance, you need to ensure that all that air is actually used to cool the engine. I think I've finally come up with a concept to seal the front of the plenum, and I've started doing a bit of work to confirm the concept will work. I'll start work on the plenum once I have confirmed the sealing concept will work.
Sunday, April 02 2006 @ 07:33 PM EDT Contributed by: Kevin Horton Views: 860
I've had a moderately productive week. I didn't get as much done as I had hoped, but you never do. I spent quite a bit of time working on items on my snag list, and even though I found a bunch of new items to add to that list, it is 20 items shorter than it was a week ago. I also got in two rounds of sand the fill on the upper and lower gear leg intersection fairings.
Thursday, March 30 2006 @ 11:31 AM EST Contributed by: Kevin Horton Views: 1130
I've been beavering away a few hours each day on the project. Monday I collated all the snag lists I've created since the start of the project. Any time I found a problem that I couldn't fix right away, or if I stopped a job part way through, I would record it on a snag list, so I would be sure to fix it later. This list covered many pages, with most of the items marked off as already completed. I decided to go through all the pages of the list, and transcribe them into an Excel spreadsheet that I could load onto my Palm PDA. It turned out that there were 75 open items on the list. I started attacking them, and got a bunch done, plus found a few new items to add to the list. I've made net progress of 10 items on the list.
Tuesday morning I removed all the flexible hoses that I had made up, so I could get them pressure tested. It took quite a while to get them all off, as some of them are difficult to get to. One of the inverted fuel system hoses had filled up with oil that had come back through the oil pump. That made quite a mess when I took it off. I made sure to label each hose as I took it off - otherwise it would have been a real jigsaw puzzle figuring out which one went where.
I dropped the hoses off at Kirouac Fluid Industries Tuesday afternoon, and picked them up yesterday. They all passed the pressure test. It cost me $60 to have all 14 hoses tested, but I figure it was worth the expense to be sure to find any problems now, rather than during the engine runs, or in flight. A leaking fuel hose could cause a fire.
Now I need to put the firesleeve on the hoses, and then reinstall them. The firesleeve needs to be clamped in place on each end. Type-certificated aircraft use nice stainless steel band clamps to do hold the firesleeve in place. Many homebuilt aircraft builders just use a few turns of safety wire, which probably works well enough, but really looks amateur. Someone on one of the e-mail lists was complaining about the cost of the stainless steel band clamps, and the tool needed to install them. Someone else suggested that automotive CV boot clamps were a suitable replacement. I spent several hours on Tuesday driving to various automotive parts places, looking at CV band clamp tools, and pricing out the clamps. I only found one place that had a tool, and it was $35. The clamps were going for $3 each, and I need 28 of them. I went on to Wick's web site, to see how much the expensive aviation ones cost - the clamps are $1.33 each, and the tool you need to install them is $7.20 for the cheap one, and $15.28 for the nice one. Time to put an order in to Wicks.
Sunday, March 26 2006 @ 08:24 PM EST Contributed by: Kevin Horton Views: 901
I'm beavering away, slowly getting little things done on the airplane. It seems that for every thing I get done, I see another one or two more that need doing. So, while I am making progress, my list of things that need doing is getting longer rather than shorter. But, if I keep plugging away, someday I will be done.
I drove out to Carp today, to meet up with RV-8 builder John Perrin. He had a Strong 304 parachute that he had used during his flight testing. He doesn't wear it any more, so he decided to sell it. I put it on and climbed in his aircraft to see how comfortable it was. It isn't as comfortable as a seat cushion, but it isn't bad. It should be more comfortable than the cushion on an ejection seat, and I've got lots of hour strapped into those. So I bought it.
I took the snow tires off both cars this weekend, and put the summer tires back on. I traditionally do this immediately before the last snow storm of the season, so I wouldn't be surprised to wake up to snow tomorrow :)
I'm starting two weeks of vacation tomorrow. I'm hoping to make quite a bit of progress on the aircraft.
Sunday, March 19 2006 @ 07:56 PM EST Contributed by: Kevin Horton Views: 1008
Early this week I spent some time securing some of the wiring ahead of the firewall. Then I noted that the starter cable was rubbing on the mixture cable bracket. In the past, I would have simply added this item to my snag list, and worry about it at some unspecified time in the distant future. But now that I am getting closer to the end of the project, I am trying to tie off those loose ends as I find them.
Securing the starter cable ate up a lot more time than I expected. I tried two different ways to attach it to an oil pan bolt with Adel clamps, but it was still rubbing on the mixture cable bracket. I eventually found a way to tie it down, but it ate up two evenings.
Then I noted that the mixture cable bracket had not been torqued. It took a bit of head scratching, but I managed a Rube Goldberg arrangement with a combination wrench, a bolt, two nuts and a torque wrench. I still have to figure out a way to torque the fastener that holds the Adel clamp that holds the starter cable to the oil pan. This one will take a bit of Red Green, I think.
I box of hardware arrived this week, so I have the stuff I need to finish off a bunch of other loose ends. Today I put in some bolts with holes in the heads to hold the flap torque tube, and safety wired them. The basic design relies on the friction from the nutplates that the bolts go into, but I wanted a more positive safety, as this is a critical part.
Sunday, March 12 2006 @ 09:45 PM EST Contributed by: Kevin Horton Views: 1053
I got a bunch of small items done this week, as it seems that every place on the aircraft I look I see some small loose end to tie off. I installed the angles that made the battery tray compatible with my smaller battery. The tray that comes with the kit is designed to accept a fairly large battery. I should be able to use a smaller, lighter one, as I have a standby alternator, and thus don't need a long endurance on battery only. I bolted two pieces of angle to the bottom of the battery tray to narrow it.
I started securing the wiring bundles ahead of the firewall yesterday. Last night we had a dinner party, and didn't get to bed until after midnight, after having consumed way too much alcohol. Today was a very slow day, as I had no energy at all. This evening I fitted several grommet shields on the firewall.
Sunday, March 05 2006 @ 07:22 PM EST Contributed by: Kevin Horton Views: 1131
After sorting out the wiring bundle/aileron push rod interference, I decided it was time to find the correct position for the rudder pedals. Van offers two different rudder pedal options - adjustable rudder pedals, and fixed rudder pedals. The adjustable rudder pedals mount on a framework that slides fore and aft, and can be locked in any position to fit different length legs. The fixed rudder pedals can be mounted in any one of four different fore and aft positions. They can be moved between positions, but it would take a half-hour or more to reposition them, and you would need to have a supply of different length links that connect them to the rudder cables.
To fit the rudder pedals, I needed to put the front seat back in, and install the rudder. I decided to try the fit of the lower rudder tip fairing, and discovered that it hits the fuselage when the rudder is moved past two-thirds travel to the right. I don't know how I missed that before, but I'll need to do yet some more fibreglas work on it to sort it out. I'm very, very glad I discovered this before I had it painted.
I had to put the floors back in so I could install the front seat. While doing that I discovered that one of the wiring bundles on the left interfered with the passenger foot wells, which are recesses in the floor where the passengers heels go. Out came the floors again so I could move the errant wiring bundle. It was still very close to the foot well, so I encased that part of the bundle in a piece of very tough piece of reinforced plastic hose. That will ensure that the bundle doesn't get chafed.
I got very little done this weekend, due to two household plumbing tasks. Yesterday I installed a new set of faucets in the kitchen. It went very well, all in all, but it still ate up 3.5 hours, once you include the head-scratching time, and the trip to Home Depot. I was feeling pretty chuffed about doing the job with only one trip to Home Depot.
But this morning Terry noted a leak from the trap in the drain under the sink. I found the leak, and carefully made a list of the parts I would need to fix it. off to Home Depot. But when I disassembled the stuff under the sink, the flange on the drain pipe from the sink broke due to corrosion. Back to Home Depot for a new drain pipe. When I went to put things back together, I discovered that the new trap I bought had a very slightly different thread than the old elbow - I thought those things would be some sort of standard. Back to Home Depot again, for the third time. Grr. Most of the day was gone.
1 comments Most Recent Post: 03/09 04:02PM by Anonymous