RADIO CONTROL PYLON RACING
Duane Gall, 1267 S. Beeler Court, Denver CO 80231
GREAT WALLS O' FIRE
It's building season. By now you should have three or four Quickies salted away and ready to test-fly as soon as the sun comes out, and you're thinking about trying that Quarter 40 stuff. Maybe with an APRA (Arizona Pylon Racing Association). Typical APRA engines are the Thunder Tiger and ASP .40s, priced around a $100 sport engine to start with, just for grins; they fly great that way.
But wait, those airplanes use fiberglass fuselages! You'd have to put in a firewall! What to do?
Because of variations in engine dimensions, firewall installation is not a typical "prefab" feature; you have to do it yourself. If you've never done it before, the thought of attacking your shiny new fish with a Moto-Tool® is admittedly rather scary.
Start with your engine, engine mount, and spinner, all bolted together into a neat little unit. Leave off the propeller. Take a long moment to decide which side of the fuselage the engine will stick out of, then draw in the approximate size and shape of the necessary hole with a felt-tip pen.
Set the engine assembly next to the fuselage and determine how far back the engine mount extends. This will be the approximate location of the front of the firewall. Put some pen marks here, too.
Take the spinner off the engine and the engine off the mount. With goggles on and the Moto-Tool fired up, cut a hole in the side of the fuselage that's just big enough to allow the engine to go in. Put the engine through the hole, with the crankshaft sticking out the front, and mount the spinner to the crankshaft once again. The worst part is now over.
If the front of the nose ring has any flashing or other irregularities on it, sand those off so the spinner backplate will fit against it nice and flat. This interface will determine your thrustline, so take care not to sand it crooked.
Get your engine mount in hand and slide it into position from behind the engine, accessing through the wing saddle area. (The edges of the wing saddle may be rough. Sand them smooth or wear gloves during this step.) Bolt the engine to the mount.
Now it's time for the firewall. On some kits the firewall will be nicely precut; on others, you'll have to do some cutting and trial-fitting yourself. Your goal is to have the firewall slide in from behind and come gently to a stop, touching uniformly around the inside of the fuselage, just as it contacts the back of the engine mount. It doesn't have to be perfect, but it does have to sit flat against the back of the engine mount.
Get some masking tape and firmly tape the spinner in place against the nose ring to maintain proper alignment. The engine and mount should now be suspended inside the fuselage, with the engine cylinder free to swing a few degrees (when viewed from the front) as it rides on the crankshaft bearings. If it doesn't, look for a bind or obstruction somewhere and get rid of it. Anything that gets in the way of proper thrust alignment now will just cause you headaches later.
While holding the engine cylinder just the way you want it, press the firewall against the back of the engine mount and sneak a couple of drops of CYA (cyanoacrylate) glue in there to hold it temporarily.
Unbolt the engine from the mount and pull the mount/firewall assembly out the way it came in. Without removing the mount from the firewall, drill all of your mounting holes (plus the holes for the throttle pushrod or shutoff, fuel lines, etc.) and install the blind nuts for the mount. Pop the mount loose, sand away any excess CYA, apply a small amount of Vaseline™ (my favorite fuel-proofing goo) to the back of the mount, and bolt the mount to the firewall. If the firewall will be permanent, and you haven't already done so, clean the inside of the fuselage with alcohol or acetone and sand it lightly so epoxy will stick to it. Slide the mount/firewall assembly into place and bolt the engine.
Remove the tape holding the spinner against the nose ring and persuade the whole assembly forward another 1/2 inch or so to allow the spinner to turn freely. (This will increase your available horsepower.) Keeping the spinner aligned with the nose ring, drop CYA around the outside edge of the firewall to tack it in place. At this point I like to pin the firewall in place with toothpicks for extra security—allowing me to take the engine out for the next step without fear of accidentally knocking everything out of alignment.
To pin the firewall in, drill 1/64" holes through the fuselage skin and into the edge of the firewall at various points (five or six will do) around its perimeter. Then cut the ends off toothpicks and jam them into the holes, securing each one with a drop of CYA.
The last step is to seal the firewall-to-fuselage joint with your favorite bulletproof permanent installation material. I like to use slow-cure epoxy and small pieces of 4-oz fiberglass cloth applied front and rear of the seam with a disposable brush. Firewalls require rigidity and permanence; glass cloth and epoxy give it.
Other parts of a fiberglass airplane should be assembled with different adhesives; for example, you don't want to use an ultra-rigid bond when installing the servo tray because you don't want to transmit engine vibration to the servos. Instead, use clear RTV (Room Temperature Vulcanizing) silicone adhesive for this purpose.
Make the servo tray from 1/8" plywood, of a size and shape that will nestle nicely into the fuselage, and run a bead of RTV along the seam both above and below the tray. This will "trap" the tray so it won't fall out even if the primary bond at the edge of the plywood should fail.
Similarly, when adding the tail feathers, you don't want a bulletproof joint. If (unlike me) you occasionally overshoot a landing and tumble the airplane, the balsa will snap somewhere outboard of the fuselage. This leaves you with a nasty greenstick fracture that's hard to repair.
Better to use a mixture of five-minute epoxy and microballoons, so that one of these unscheduled airtravails will result in a clean break or stress crack that you can easily fix with CYA. Remember to have someone else safety-check the model before you go up again.
The 1998 Silver Cup
In my old stomping ground of Michigan and Ohio, the last weekend in August has always been reserved for one of the best, if not the best, contests in Quarter Midget (now Quarter 40)—the Silver Cup, jointly hosted by the Toledo Weak Signals and Toledo Flying Tigers clubs and sponsored by Les Haddad's hobby shop, The Hobby Stop.
Les has been a stalwart in supporting racing in the Midwest since before I started—which, without getting into any embarrassing details, is a long time.
I was unable to attend this year, but Wayne Yeager was gracious enough to supply this play-by-play:
"The 27th annual Hobby Stop Silver Cup race went off again this year, with 29 entries and great weather. There were a few guys entered who traveled from down South, so we appreciate them making the effort.
"Racing was the usual, tight and fast for the most part. Six rounds were completed on the first day after a very shaky start because the speeds and the light were not conducive to seeing colors very well; as a result, three reflys were required in the first round alone. (These pilots might have benefited from last month's column on color schemes! —DG)
"However, we struggled through the second round with only one refly, and after a lunch break, the sun was now higher and the models were easier to see; and as a result, we breezed through Rounds 3, 4, 5 and 6 without a problem.
"At the end of Day One, Tim Lince and Joe Dodd were tied for the lead, two points away from a perfect score, which is an indication of the competition level. Over the two days of racing, no one was exempt and there were many zeros recorded from some of the top guns, as they were mucking it up in such close quarters that cuts were everywhere.
"The traditional Saturday night steak-and-corn cookout was once again a great success, as most of the fliers stuck around and everyone had their fill of beef, corn, tomatoes, and the most scrumptious lemon cake you ever sank your little dentures into.
"Sunday's racing was scheduled for only three additional rounds so we could host the annual Ron Haddad Memorial Trophy Dash, held every year in memory of the late Ron Haddad, Les Haddad's brother.
"We completed the three rounds in the morning, and while lunch was being consumed, we married the dash and started it right after a flyoff for third through fifth places among Marcus Blanchard, Craig Grunkemeyer, and Bill Johanson. Blanchard won this one by staying clean as both of the other guys cut.
"Joe won straight out with no ties, and as a result, no flyoffs. Joe deserves a big 'pat on the back' because the limelight is usually on his flying partner Grunk, and it was good to see Joe on top for a change (not to take anything away from Grunk).
"We ran four heats of three fliers in the dash, with the plan being that the winner of each heat would move on to a four-airplane final heat. However, something weird happened in the first heat, as three of the four airplanes cut out, and the last guy, Dean Stone, had it made—but his caller yelled out, 'You've won. You've won!' and at this point the aforementioned Mr. Stone immediately pulled up and shut off his engine, two laps short of 10. Oooops.
"So the final was a three-airplane heat won by Craig Grunkemeyer, who also had Fast Time for the weekend at 1:06.13.
"Now it was time to pass out the silver (literally, in this case) and hit the highway.
"The workers were thanked, Les Haddad was thanked for hosting this race, promises of 'we'll be back' were stated and everyone went home happy, I hope."
1998 Toledo Weak Signals/Flying Tigers/Hobby Stop Q40 Silver Cup—Final Standings
- Joe Dodd — 34 pts., 1:10.32
- Dean Stone — 33 pts., 1:06.76
- Marcus Blanchard — 31 pts., 1:07.78
- Craig Grunkemeyer — 31 pts., 1:06.13
- Bill Johanson — 31 pts., 1:09.25
The Vision Thing
Other than decent eye/hand coordination, probably nothing is as essential to success in racing as good eyesight. If you're lucky enough to have been born 20/20, you probably don't realize the hassle the rest of us go through trying to attain and maintain the ability to steer our models around the course.
That thin film of exhaust oil and wind-blown dust that you may notice furiously attempting to wipe off our glasses between heats is only the proverbial tip of the iceberg.
Now there's an alternative. It isn't cheap, and it isn't risk-free, but I am happy to report from personal experience that the new LASIK (Laser-Assisted In-Situ Keratomileusis) eye surgery can take you from the white-cane category to the Right Stuff category in about 10 minutes.
At this writing, I am four weeks post-op in one eye and five days post-op in the other. The first eye has already stabilized at 20/15; the second appears to be following suit. I was able to fly a fast sport model comfortably last weekend.
Since I took the plunge, I'm told that a number of top-name model pilots have had this procedure. It's no substitute for practice, of course. But if you're seriously questioning whether to keep fighting with glasses and contact lenses, or just bag the whole RC thing and build ships in bottles, ask your doctor.
Transcribed from original scans by AI. Minor OCR errors may remain.
