When you and your father have built multiple airplanes, deciding on the next project is always a challenge. More so if you have a pickled Lycoming O-235 with a fresh overhaul sitting in the corner of your hangar.
Father and son Ron and Paul Lutz from Wadsworth, Ohio, had just that problem. They started by building a Van’s RV-9A to fly behind the mighty Lycoming. They had the airframe on its gear when they decided that wasn’t really the plane for them. Paul built an RV-6 when he was in college, which he still owns, so they were well versed in the RV cult. Ron, Paul’s father, had scratchbuilt a Christavia—since sold and missed by both. The Christavia was followed by a Thatcher CX-4, which Ron still flies. After owning a fleet of both high- and low-wing aircraft, the duo decided another high wing was their next plane of choice.
About the time they were in negotiations to sell the RV-9A project, RANS came out with the S-21 Outbound. This got the Lutzes thinking the S-21 might be a good project. However, like the RV-9A, they didn’t want to build a plane with a “small” engine. As they looked around the RANS website, they discovered the S-20 Raven could be powered by the O-235, and the S-20 shares the S-21 aluminum wing. As an option, they could select a rounded vertical stabilizer and rudder, giving the S-20 an “old school” look. The S-20 fuselage is made of steel tube covered in fabric, a medium both were familiar with. In addition, the empty weight of the S-20 should be less than an S-21—88 pounds less, according to the RANS website.
The little Lycoming, a light fuselage, and an efficient wing made the S-20 sound like the perfect project for the Lutzes. One of their airport neighbors had started on, and has since completed, a RANS S-21, so they would have someone nearby to assist if they needed help or had questions.
The check was written, the kit arrived, and building commenced.
Paul commented on how quick and easy the wings were to assemble and wished every plane went together as easily. The use of pull rivets and very clear, accurate building instructions combined to make completing the wings a simple and pleasurable task.
After finishing the wings, they moved on to the fuselage, which went together quickly. So it was time to mount the engine.
RANS sells a mount for the IO-340 “Lyclone” engine, which was just a few pounds heavier than the O-235 sitting in the corner of the Lutz hangar. Paul and Ron had two issues with the engine mount RANS offers: It was a dynafocal mount, and the O-235 in the corner has a conical mount. The second issue was the limited space between the back of the engine and the firewall. This space restricted builders to using electronic ignitions. While they both like the benefits provided by electronic ignitions, neither felt comfortable flying behind an electrically dependent aircraft. They would much prefer to fly behind standard magnetos—or better yet, P-Mag ignitions. P-Mags are electronic ignitions that have internal generators and can self-power should the aircraft have an electrical issue. With P-mags, no backup electrical system, battery, etc., is required.
During a conversation with a friend—aka the author of this article—it was suggested they build a “swing-away” engine mount similar to what is found on a Cessna 195 or Piper Super Cub.
Being able to swing the engine aside would give them access to the accessory case for all maintenance issues. The next problem was designing and welding the appropriate engine mount.
Again, that friend came to the rescue and introduced them to VR3 Engineering. The staff at VR3 understood the problem, rendered the engine mount in CAD, and emailed the drawings to Paul for review. After a couple of suggestions, VR3 cut the tubes to the correct length—complete with fishmouth ends that allowed the tubes to “snap” together for welding. VR3 also offers welding services, but Paul and Ron had the mount welded locally.
Once welded, the mount was bolted to the airframe and the engine was hoisted in place. It looked almost perfect except for one problem: The engine thrust line was lower than desired. Getting back on the phone with VR3 resulted in a new rendering—completed, approved, tubes cut, and shipped to Ohio. Mount number two was welded and fit perfectly, with the engine lining up exactly where it was supposed to.
As I write this, the father-and-son team are putting the finishing touches on their S-20 and should complete the first flight prior to the end of the year.
Photos and video by Paul Lutz.
On my Grumman AA-1B the factory engine mount will swing out the same way. I need to do that if I have to pull a mag as the clearance to the firewall is tight. I always support the engine with a hoist when doing this.
AA-1B owned since 1981. Replaced the 0-235 with a 0320-A2B in 1983.
Also own an American AA-1 Yankee with a 0320-E2G.
This is what is needed on the RV-12!!!
Great story, Bill. I’ve always envied the C-195s their swing-away mounts and often wished I had one on my elderly C172A.
But am I just being anal, or is it acceptable (assuming no access issues) to insert the bolt from below? I always thought that (absent manufacturer’s stipulation) a bolt should be inserted with the head up (and/or forward).
Nevermind. Atrocious Internet speeds today due to the BP/ICE invasion this morning. That photo caption didn’t load until after I asked the question.
In the immortal words of the late and long lamented Emily Litella, “Nevermind.”
At least you recognized it as an issue and spoke up. Yes, as the caption noted, the upper corner bolts could not be installed from above.
Let’s hope before they start flying that new engine they remove the “lifetime” filter and replace it with a conventional paper one. The lifetime filters have been shown to be horrible at removing particulates from oil, you don’t want to risk a new engine to one.
The “lifetime” filters work fine, if you you change your oil at the same interval (25 hours) that are used for the stock oil screen that came on this engine.
Beautiful, the entire plane. They sure do good work!
So I am looking at this and my first thought is “cool”. Then I start to wonder what the overhung weight of engine and prop will do to those welds on the hinger side when the mount is open?
Not a concern. Paul supports the engine with his engine hoist when swinging the engine, and he only opens it 10 to 12 inches. He does not swing it all the way over. Also this mimics what Piper did on the Super Cub and Cessna did on the 195, both with no history of problems.