One Rivet At A Time

Welcome to Kevin Horton's RV-8 Project
Saturday, December 20 2014 @ 03:28 AM PST

Big Picture

This blog covers the construction and flying of a Van’s Aircraft RV–8, built and flown by Kevin Horton.

I had thoughts of someday building my own aircraft from the time I was a teenager, but never took it beyond the fantasy stage until after arriving at Cold Lake, Alberta as a freshly minted test pilot. One of the other test pilots there was building an RV–4, and he told me fantastical tales of the performance and flying qualities. I did some research, and learned that Richard Van Grunsven (Van), had designed a very well loved all-metal single seater, the RV–3, followed by the two-place tandem RV–4, and the two-place side-by-side RV–6, all with tail-wheel landing gear. And then the RV–6A, with tricycle landing gear. All models had a good all-round performance and were reputed to have excellent handling. I was tempted, but the time wasn’t right. As always, there were one or two things to get done in life first, and then the time would be perfect.

A few years passed, and I eventually realized that as soon as you got one of those roadblocks out of the way another one appeared, and the “perfect time” never arrived. If you wanted to get something done in life, you just needed to get started.

One day I learned that Van had come out with the RV–8, which was two-seat tandem like the RV–4, but with much more baggage space, 10 gallons more fuel and a wider cockpit and instrument panel. I had visions of quite a bit of cross country flying, possibly in Instrument Flight Rules (IFR), so baggage space, fuel capacity and a large instrument panel were all attractive. This was the trigger I needed to get off my butt and start this grand project. I did a demo ride at Oshkosh in 1997, and was very happy with the aircraft, so I ordered the tail kit.

I looked at the tail kit as the litmus test - I would use it to see if I enjoyed the building process. If I did, I would continue. If not, I would sell the tail kit and drop the idea of building an aircraft. I found that the building process was very enjoyable, and was good way to relieve stress after a busy day at work. I carried on, doing a bit at a time, like the proverbial mouse eating the elephant. And one day, many years later, I had an aircraft. And it flew.

Construction started in the fall of 1997, and first flight was almost 11 years later in August 2008. The beautiful Golden Hawks paint scheme was finally done in the spring of 2010.

The aircraft has about 230 hours on it now (May 2013), and Terry and I have finally started to do some regular traveling with it. We took it to the huge EAA Fly-In at Oshkosh, WI in 2010 and 2011. I got to Sun n Fun in 2012, and we have flow it to Nova Scotia and Wisconsin several times. I try to fly the aircraft every week that I am home, if the weather cooperates.

Scroll down for the latest detailed news.

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Winter Has Arrived

General News

Winter definitely arrived last week, with several days of snow, with roughly 20 cm of total snow fall. I headed out to the hangar Saturday AM to get the snow blower going and clear the snow. I had started it about three weeks ago, to make sure that it had survived its summer of hibernation - that first start was a definite struggle, so I wasn’t sure what to expect this time. I got lucky - it started right up. It took about an hour to blow the snow off the entry to the hangar, chip a few big ice ridges from where the airport snow plow had turned around, and clean up with a shovel.

The ceiling was low when I arrived at the airport, but it had cleared out nicely by the time I was done clearing snow, so I rewarded myself by going flying.

Many of the lakes have frozen over, but the ice is still way too thin for any intrepid ice fishermen to set up camp.

Some other lakes have quite a bit of water flowing through them, as they are part of the Rideau River system, so they haven’t frozen over yet.

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More Stall Speed Testing

Flight Test

We had a nice sunny day today, so I went flying. Last time I flew, I did some stall speed testing, using an experimental four leg GPS method, and I was puzzled that the results were about 3.5 kt different from the earlier testing I had done using the same method. After thinking about it a bit, I realized that I had possibly done the stalls with the mixture set differently than from the earlier flight, and that this might possibly have resulted in a different idle speed, and a different effect from prop discing drag. I wanted to investigate this today.

We were under the influence of a strong high pressure area, with the Ottawa altimeter setting at 30.81, and fairly cool temperatures (Ė10įC or 14įF), so the density altitude at Smiths Falls was very low (3200 ft below sea level, or about 10% higher density than sea level with standard temperature). The plane was a veritable rocket ship under these conditions, reaching over 140 kt before the end of the 4000 ft runway.

The air was smooth, so I did my testing at 4500 ft barometric altitude (about 3700 ft pressure altitude). First, I did numerous stalls with mixture at full rich, and then repeated with the mixture set to roughly where I remembered it from the previous flight. I noted that the stall IAS was about 3 kt lower with the mixture rich than it was with the mixture leaned. The engine rpm at the stall was about 80 rpm lower with the mixture rich than with it leaned, which supports my theory that variations in prop discing drag signficantly affect the airflow over the inboard wing, leading to variations in stall speed.

Then I did four four-sided box pattern stalls (i.e. 16 more stalls) with the mixture rich - the results, when corrected to 1800 lb weight, are in between the results from the previous two flights. I suspect the engine idle rpm at the stall may vary with altitude, which may affect the stall speed on my aircraft. Iíll continue the science project on future flights, doing testing at a range of altitudes.

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General News

I got the Geeklog downloads plugin installed and working, and have begun to add the downloads from the other host. I’ll add the remaining files over the next few days. You’ll find them in the Downloads section. New files added will be visible in the What’s New block over on the right.

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Stall Speed Testing

Flight Test

I had day off on Friday, and took advantage by doing a firewall forward inspection and then a short flight. I finally had weather that allowed me to climb high enough to gather some more stall speed data using a four leg GPS method. The results from this flight is a real puzzle when compared to the previous test a few flights ago.

The two test points (four legs each) looked to be excellent quality, with extremely low standard deviation of the four calculations from each test point (0.2 kt and 0.0 kt for the two test points). The two test points gave similar speeds, with only 0.1 kt difference between the two points.

The two test points on the earlier flight also appeared to be reasonably high quality, with low standard deviation (0.8 kt and 0.2 kt). The two test points on that flight giving results within 0.3 kt of each other. But, if I correct the stall speeds from the two flights to the same weight, the stall speeds from Fridayís flight are about 3.5 kt faster than the stall speeds from the earlier flight.

My aircraft has a three blade MT aerobatic prop, and it has a huge amount of prop discing drag with the throttle is at idle, with the prop control fully forward. I suspect that the airflow over the inboard wing is disturbed in this condition, and that results in the stall speed being several kt faster than other RVs with more typical props. I donít recall where the mixture control was during the stalls on the earlier flight, where the stalls were about 2000 ft higher (7000 ft vs 5000 ft). I wonder if the rpm at idle, and thus the discing drag, might vary depending on where the mixture control was. Iíll experiment with this on the next opportunity to try to get to the bottom of this puzzle.

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New User Registration Working

General NewsI found and fixed the problem with new user registration. †It should be working now.
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New User Registration Broken

General NewsNew user registration seems to be broken at the moment. †I'm looking into it.
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New Site Host

General News

If you are reading this, the move to the new web host worked. I made the move a couple of days ago, but had a few hiccups to sort out. †It seemed to work OK during my testing before switching the domain from the old host to the new one, but changing the site from an IP address to a domain two days ago somehow fouled up the fragile balance in the forces of the web, and the site stopped working correctly. †I finally found the Rescue function in Geeklog, and it immediately pointed out the problem - it was an easy fix once I knew what was screwed up.

There is a risk of issues with user log in, especially with the Safari browser. It was screwed up earlier, but it looks to be working now. †However, I'm far from certain that I've seen the last of this problem. I did a clean up of the user list, as the old site had collected many tens of thousands of users who had registered in the hope of creating comment spam. †There is a chance that I may have deleted a few valid accounts in that clean up. †If anyone finds that they cannot log in, please inform me - I have a backup copy of the old user info, and I should be able to manually copy it back.

The file downloads that were on the old site aren't up and runnign on the new one yet. †That will be be coming soon. †Same thing with the image galleries.

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Van's Visit

General News

I had a quick business trip to the Portland, OR area this week. Flew down on Wednesday, one day of meetings, and flew back home on Friday. After the trip came to light, I took a look at the map, and saw that the meeting site was only about 15 minutes drive from Van’s Aircraft.

I grabbed a 6 AM flight out of Ottawa on Wednesday, so I would arrive in Portland by mid-day. I drove down to Van’s after lunch, and did a factory tour.

The operation is smaller than you would expect, given how many kits are sold each year. Van does an excellent job of using components on multiple aircraft models, which helps reduce the number of different parts that must be kept in inventory. The efficient use of space helps them keep down the cost of the kits.

The manufacturing area is busy, as they make the vast majority of the aluminum parts that go in kits, or to the QuickBuild factory in the Philippines. Here we see RV–7, –8 and –10 QuickBuild fuselages waiting for an order.

RV–10 cabin tops and RV–8 QuickBuild wings.

This WW-II vintage electric rivet squeezer is used to assemble RV–12 wing spars.

Two Trumatic computer controlled punches quickly trim sheet metal parts to shape and punch rivet holes. The repeatable accuracy from these punches is what has allowed Van’s to move to matched hole construction on newer models. My early series RV–8 was the previous generation, with prepunched holes only in the skins - the builder had to carefully align the holes in the skins on the centre of the flanges on the bulkheads and ribs, then drill holes through the skin into the structure. With matched hole construction, the bulkheads and ribs arrive with holes in them. This saves a huge amount of time, and obviates the requirement for jigs.

The prototype RV–14A, RV–6A and RV–10 aircraft, parked outside the Van’s Aircraft hangar. I’m pondering building an RV–10, as we’d like the option of carrying friends and family with us, so I did an RV–10 demo flight with Ken Scott. The RV–10 has a wide, tall and long cabin, with much room than most four seat aircraft. The visibility from the cockpit is expansive, the stick forces are relatively light, and the performance is excellent. I’d like to find a partner for the RV–10 though, as I don’t want to sell the RV–8, and it makes no sense to own two aircraft.

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Web Site Move Coming

General News

The website was down for a few days this week, and I have no idea why. I hadnít changed anything since the last time I know it was working, and tech support wouldnít admit to making any changes on their end. After two days of complaints from me, it suddenly started working again.

By the time they got it working again, Iíd already signed up for hosting services at SiteGround. SiteGround gets much better reviews than my current site host, and itíll be a bit cheaper. Iíve got the site mostly working on the new host, but I plan to update to the latest Geeklog software before I switch the site over. If I started over today, Iíd probably choose a different solution than Geeklog, but it is easier to stick with it than move all the content to a new platform.

There may be some turbulence during this changeover, so keep your seat belt fastened.

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Another Short Flight

General NewsSaturday I did some maintenance on the aircraft, then got a short flight off in the afternoon. I had hoped to do some more testing of an experimental technique to determine stall speed using GPS data, but I didn't get airborne early enough in the day. We had an overcast ceiling by the time I finished the maintenance, and it was bumpy below the cloud, so there was no point wasting time doing the tests, as I knew that the data quality would be poor. Maybe next weekend.
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