Tailwheel Steering Pontifications
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- Written by Kevin Horton
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One of the maintenance items I checked out on Saturday was the tailwheel steering. There was a very illuminating thread on the Vans Air Force forums recently. The original poster had ground looped his RV–8 while landing in a moderate right crosswind. Luckily, nothing was damaged except his ego. He wasn’t 100% sure what had triggered the ground loop, but he suspected that the tailwheel may have unlocked from the tailwheel steering during rollout.
The ensuing discussion was quite interesting, as it highlighted a potential issue with single-are tailwheel steering linkages, as is fitted to our RV–8. It seems that the typical geometry of these linkages puts the bellcrank at the tailwheel pivot at a different angle than the rudder horn where the front end of the linkage attaches. This results in more tailwheel travel to one side than to the other, and this may cause the linkage to unlock at full rudder travel.
I check our tailwheel on Saturday, and sure enough, full left rudder turns the tailwheel far enough that the unlocking cam disengages it from the bellcrank at the pivot. In principle, the tailwheel should remain locked to the linkage at full rudder, unless you tap the brake to tighten up the turn, in which case the spring in the linkage allows the wheel to turn further, causing it to unlock.
I played around with the available adjustment in the linkage, but it was not possible to set it up so that it would remain locked at both full right and full left travel. I studied the geometry and concluded that there are two possible fixes.
- Purchase or fabricate a tailwheel pivot bellcrank that has the end of the arm swept back further, so the line between the pivot and the end of the arm is parallel to a line between the rudder hinge and the forward end of the steering linkage.
- Purchase a longer rod end for the steering linkage and drill a new hole for the front end of the arm. The new hole would be further ahead on the rudder horn, which would make the angle between the rudder hinge and the linkage arm attachment close to parallel to the angle between the tailwheel pivot and the aft end of the linkage arm.
Note: This issue is not present if the builder uses the two chains and springs that Van supplies with the kit. I had tried those, but found that the chains hit the bottom of the rudder fairing, which prompted me to switch to the single-arm steering linkage.
Busy Late Summer
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It’s been a busy time since my last update.
Shortly after getting back from Oshkosh, I flew the RV–8 to Yarmouth, NS to visit my parents and sister for a week. It was a great trip in all respects.
While in Yarmouth, I took my niece and nephews up for flights.
The hills in western Maine were as attractive as ever.
I headed back to Vancouver Island on Labour Day, for two weeks of Twin Otter flight testing with Viking Aircraft. We got everything done on schedule, so I flew back home on Friday.
Flying over Vancouver Island was particularly scenic on this trip, as one of the flights took as across the middle of the island, as we needed the very smooth air over the Pacific Ocean, west of the island, for our testing.
Saturday I spent a few hours at the hangar taking care of a few maintenance items.
EAA Airventure Fly-In
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During my first few Oshkosh fly-ins, I would always try to see everything, which resulted in walking untold numbers of miles every day due to the huge site, with aching feet and legs by the end of Day Three. Now I try to prioritize things a bit, and only focus on the highlights. I also attempt to make better use of the tram service, and to plan the week so I only have visit the most distant areas once.
Sunrise in Homebuilt Camping
I have also made quite few friends there, so I take the time to stop and talk to folks that I only see once a year. Oshkosh is more about the people than the planes for me now.
I see Mark Richardson more often than once a year, as he lives in the Ottawa area. But, we did enjoy the output of his propane fuelled espresso maker.
On Monday, Terry and I went though the “sea of RVs” (i.e. the huge parking area filled with various models of the Vans Aircraft designs). We also went through one large section of the outside aircraft exhibitors. It was very hot and muggy, so we rewarded ourselves with a much enjoyed ice cream mid afternoon.
Tuesday AM, we went through the Vintage Aircraft Parking area and had our annual RV–8 builders/flyers/wannabees meeting. We’ve been doing these for over 15 years now, and it is always good to talk to the other builders.
Wednesday morning was warbirds, followed by a couple of interesting forum presentations. The highlight was an interview with Col. Richard Cole, the last surviving member of the Doolittle Raid. The flight of the 16 B–25 bombers off the Hornet aircraft carrier to attack Tokyo in April 1942 was a great boost to the American moral, in the early days of the US part of WWII. Col. Cole is 100 years old, and while he appears quite frail, is obviously still very sharp, with excellent memory of his role as Jimmy Doolittle’s copilot for the raid.
Terry bailed out on a bus Thursday AM, to get off site to be picked up by two of her sisters. She spent the rest of the week in Manitowoc with them. My brother and his son arrived Thursday morning, and we spent the afternoon walking over much of the site. My legs had enough by 17:00, so I left them and rested for the evening.
Friday AM, my brother, his son and I took a bus to the Airventure Seaplane Base. This is a very peaceful place, hidden in the trees around a lagoon on Lake Winnebago, SW of the airport. Friday afternoon, we parked ourselves on the flight line to watch the airshow. The highlight was the Snowbirds, but most of the other acts were excellent as well.
Saturday AM, I packed up and joined the long congo line of aircraft taxing for departure. I did the short flight to Manitowoc to meet up with Terry again. We spent Sunday there, and flew home on Monday.
On the way home, we deviated from our usual stop of Sault Ste. Marie, MI. This time, I did some research on fuel prices, and was surprised to learn that the fuel in Gore Bay was cheaper than the fuel in Sault Ste. Marie, MI. And, the route through Gore Bay was 18 nm shorter than the route through Sault Ste. Marie. So, we cleared Customs in Gore Bay. The Customs lady was extremely friendly, as was the FBO gal. CYZE will likely be our usual stop on the way back from WI.
EAA Airventure Fly-In - Arrival
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I’ve been rather delinquent in updating this site lately - sorry about that.
Terry and I had a great trip to EAA Airventure (a.k.a “Oshkosh”). We were airborne at 08:00 on Saturday, 23 July and made it to Manitowoc, WI by noon, via a fuel, lunch and Customs stop in at Sanderson Field in Sault Ste. Marie, MI. We spent the night in Manitowoc, staying with one of Terry’s sisters.
We had planned to fly into Oshkosh early Sunday morning, to beat the usual Sunday afternoon rush. But, the weather had other plans, with a bunch of thunderstorm cells moving through Oshkosh first thing in the morning, with the leading edge of the ceilings arriving at Manitowoc before the trailing edge was finished pounding Oshkosh. We waited anxiously for the weather to improve in Manitowoc, and rushed to the airport around 10:00 when the weather report suddenly showed an 8000 ft ceiling. But, as we arrived at the airport, I could see a lot of very low cloud around, and it was clearly not suitable for VFR flying, despite the nice report. Sure enough, a few minutes later the reported weather was revised to 600 ft ceiling. We waited. And waited. And went for lunch, and waited some more. We finally gave up and went back to the sister’s place, as Manitowoc was still bouncing between 400 and 600 ft ceilings, while the rest of Wisconsin enjoyed sunny skies. The problem was that Manitowoc is on a bit of a bump protruding into Lake Michigan, and the wind was blowing moisture in off the lake.
Finally around 14:00 the skies opened up, so we rushed to the airport and headed for Ripon, to start the special arrival procedure. I switched to the Fisk Approach frequency, and was dismayed to learn that one of the arrival runways was closed and that they were putting all arrivals into holding patterns around Green Lake and Rush Lake. We joined several dozen other aircraft in the Green Lake holding pattern.
Shortly after we arrived in the Green Lake hold, they started accepting arrivals again, which meant that they first started emptying the Rush Lake holding pattern, followed by emptying the Green Lake pattern. When they empty the Green Lake hold, you are supposed to continue single file around the lake until you are heading NE, then proceed to Ripon. But, it seems that there were quite a few folks who decided that they were special, and the procedure didn’t apply to them. These special idiots all turned directly towards Ripon, so the sky was full of aircraft proceeding from various parts of Green Lake, all converging on the same point. Grr. We managed to avoid everybody, thanks in no small part to Terry’s great work at pointing out other aircraft that I hadn’t seen yet.
After we passed Ripon, and were following the railroad tracks towards Fisk, a Piper Cherokee came up from the south and parked himself 300 ft off our right wing tip. He should have gone to Ripon first, rather than trying to break into line, and I don’t think he even saw us. I didn’t want to break out of line due to his incompetence, so I proceed on, while watching him like a hawk. Fortunately the Fisk controller was on the ball, and instructed him to turn right for the runway 36 arrival, and we were told to continue straight ahead for runway 27, which provided separation between us.
Things got crazy again as we approached the airport, with one guy wandering all over the sky looking for the downwind leg, and a Gulfstream business jet on an IFR arrival which forced several VFR arrivals to go around. We landed around 16:15, did a long taxi to HomeBuilt Camping, and set up camp in extremely hot and muggy conditions. You can see our landing on YouTube - we were instructed to landing on the green dot - it looks like I missed by about 50 ft.
Sunset in Homebuilt Camping.
More to follow soon.
Second Post-Engine-Install Flight
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I took yesterday off from anything related to RVs, as I had spent the previous eight days at the airport. Today was another sunny day, so I went flying again - another 2.5 hours in the vicinity of the airfield.
Before the second flight, I pulled the cowlings to inspect for leaks or anything else amiss. I found one small oil leak in the vicinity of the prop governor, but it isn’t clear where it is coming from. This looks exactly like the mysterious leak I chased for the last several years. Oh well. I also found a loose connection at the fuel pump vent line. I pulled the oil filter, cut it open and inspected it. It looked completely normal, with the expected very small number of tiny metal pieces, typical after an overhaul.
The flight itself went well, but it was pretty boring staying within gliding range of the airport. I’ll go a bit further afield now, but won’t stop at another airport until I get at least 10 hours on the engine.
Flying again!
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I finally got the RV–8 flying again today - the first flight since late January. The engine had been at Aerosport Power since late March. They were ready to ship it back in mid May, but I needed to pay the bill first, and we were on the road on vacation in Alberta and BC. I paid the bill after we got back home at the end of May, and the engine arrived on June 8th, shortly before I left on a two week trip to Viking in BC. I went to the hangar every day after I got back, but it was steaming hot in the afternoons, so I would eventually melt down and stop for the day.
I had it ready yesterday afternoon for a ground run to check for leaks, but the starter barely cranked it over, so it never started. Slow cranking has been a recurring problem, and in the past it has always been caused by a bad connection in the power or ground paths somewhere between the battery (in the rear fuselage) and the engine.
This morning I cleaned and tightened every connection in the power and ground circuits, and now it cranks like crazy. I did a ground run just before lunch to check for leaks, check ignition systems, prop governing, engine instruments, etc. Everything check out, so after lunch I did the first break-in flight. I used the profile recommended in Lycoming Service Instruction 1427B - 60 minutes at 75% power, then 60 minutes alternating between 65% and 75% power, then 30 minutes at max power. Of course, now that I look for a link to SI1427B, to put in this post, I find that it was superseded by SI1427C, which no longer has the final 30 minutes at max power.
The aircraft and engine were working well. I need to adjust the oil pressure slightly. It was in the normal range, varying between 66 and 71 psi, but I’d prefer to see it closer to 80 psi. I’ll tweak the pressure relief valve before the next flight. I’ll also pull the cowlings to check for leaks or anything else amiss, and cut open the filter to check for metal.
It was great to get the RV–8 flying again! Now I need to reteach it how to land. The landing was OK, but not as tidy as I would like. Something to work on before Oshkosh at the end of the month.
