Racing with Voodoo

Posted on May 31, 2019 by admin

This season, I’m racing with Voodoo. What? Oh. No. Sorry. Not the famous Reno Racing plane by the same name. I’m talking about a speed modification that uses some aerodynamic Voodoo to improve Tess’s performance in our never-ending quest to crack the mac barrier in an Ercoupe. Or at least just go fast enough to securely maintain our title of the World’s Fastest Ercoupe, and to keep those pesky Cesena 150s and 152s behind our twin tails in the SARL races.

So this might be our sketchiest speed mod yet, but here’s the tale: One of the bad things about having your plane in the shop is that you spend too much time sitting at home thinking about airplanes, instead of being out at the airport having fun with them. And thinking about airplanes at home often entails surfing through various online catalogs of airplane stuff, and discovering things that you were perfectly happy not owning when you didn’t know they existed, but now can’t live without.

This is why I now have Wig-Wag lights on Tess. But they’re not the only thing we added while waiting for our nose strut to be rebuilt, and then waiting for UPS to locate said strut after they lost it.

I also added Voodoo Propeller Tape to Tessie’s prop. Well, that’s what I call it, anyway. It’s officially called a Propeller Vortelator. It’s a distant cousin of the aerodynamically unlikely vortex generator, which is a small plastic or metal fin which, when glued to your wing along with a bunch of other little fins, does amazing things. Things like lower your stall speed, improve controllability, reduce your takeoff run, and more. How on earth do they do that?

Well, that’s what I was told, anyway. Apparently, the little fins create mini vortexes of air that delay flow separation in the boundary layer, and…

Yeah, like I said, magic.

So when I read about something similar for propellers, it didn’t strike me as impossible. Hey, if a bunch of fins on a wing can work magic on the airflow and improve performance, why wouldn’t something similar work on the prop? A prop is just a perpendicular spinning wing, after all. The advertising copy for the Vortelator—which is made by Aircraft Development, the same folks that make the Slick Air coating that we use to reduce airframe drag—say that, “Vortelators will cause the boundary layer to stay attached to the propeller surface for a greater distance, and to keep the boundary layer thinner. The net result of these two actions is that it reduces both the profile drag and skin friction drag components of the parasite drag.” Going on, they said that the Vortelators are placed on the most inefficient high drag areas of the prop, making it more efficient across its span. As I didn’t understand what they were saying, that didn’t impress me much.

But they also said it would improve my speed by 2 to 4 mph. ThatI understood.

I placed an order.

Now, I knew the Vortelator was some sort of tape, but I couldn’t tell much about its form factor from the pictures at Aircraft Spruce’s website. I think I pictured a row of mini vortex generators, or a quasi-washboard ribbon. I’m sure you can picture my disappointment when my box of Voodoo Propeller Tape arrived, and I discovered that it was nothing more than a piece of flat, thin, clear self-sticky plastic tape—cut in a zig-zag pattern.

Seriously? I was about to send it back in disgust, but decided to do some more research first. The first thing I found was that I couldn’t find anyone who had actually used it. Rather, all I could find were people who hadn’t used it, but nevertheless felt justified in trashing the mere idea. They’re probably the same people who poo-pooed vortex generators when they were first introduced, then later quietly installed them on their planes.

Next, I discovered something called turbulator tape, which is a big deal with the sailplane crowd. Apparently, most current production sailplanes use it to improve aerodynamics, and many older ones are retrofitted. Guess what? Yeah. It’s nothing more than a piece of flat, thin, clear self-sticky plastic tape—cut in a zig-zag pattern.

Hmmm… Those sailplane folks sure know their aerodynamics, even if they don’t have propellers.

But there’s more: The RC model crowd rave about zig-zag tape. Granted, their planes don’t have pilots in them, but they are honestly and truly miniature aircraft. And zig-zag tape is even used in archery to improve airflow of the tail “feathers” of modern carbon fiber arrows for increased accuracy. Who knew?

And although Voodoo Propeller Tape sure looks disappointing to the naked eye, in all things aerodynamic, small changes can net big results. So maybe some thin zig-zag sailplane/model plane/archery tape near the hub of Tess’s prop might make that ol’ piece of aluminum work better.

What the heck, it didn’t cost that much, it’s already paid for, it’s STC’d for my prop (which only means the government thinks that the product is safe, not that it actually works), and my wrench turners don’t want much to install it. And who knows? Maybe it will make Tess shoot through the air like an arrow. Rather than sending it back, I had my team put it on the prop.

So this season, we’re racing with Voodoo.

Flasher… but not like you’re thinking

Posted on May 3, 2019 by admin

“Traffic, your two o’clock, three miles, seven thousand five hundred, inbound,” said the tower.

“Looking for traffic,” I replied, squinting my eyes, leaning forward in the cockpit, and scanning the sky above me at my two o’clock. Actually, I’m not supposed to say “looking for traffic.” The proper response is, “negative contact.” But looking is commonly used by pilots, and that was what I was doing.

Looking. Desperately looking.

Then the other plane was two miles from me. Then one. Then, according to the tower, it was, “no factor.” I never did see it. In fact, having done a number of test flights in the busy Santa Fe airspace, and flying out of Santa Fe with Lisa in Warbler during her training, I’ve become aware of just how damn hard it can be to spot other airplanes. Even when they’re very close. And even when someone is telling you where to look.

And that began to worry me.

True, mid-air collisions between two airplanes are exceedingly rare, but they do happen. And we’re at much greater risk than the average airplane, because we’re a slow racer. Yes, it’s true. While Tess is literally the fastest Ercoupe in the world, we’re still among the slowest planes in the Sport Air Racing League. As such, we’re often relegated to the “short course” in races so that we can be back before the beer gets warm and the girls get cold.

Oh dear. I’m told I can’t say such sexist things anymore.

Let me try again… so that we can be back before the rest of the racers fly back to their home bases, re-fuel and clean their planes, have dinner, kiss their kids goodnight, and watch the late show.

The short course is usually just the main race with a few turns lopped off to make it shorter. The goal is to have most of the planes back about the same time for the awards. The problem is that, realistically, this means that I enter the pack somewhere in the middle of the returning racers, and I’m coming in from a different direction. Naturally we have radio procedures and safety protocols, but anything I can do to make Race 53 more visible increases everyone’s safety.

My first thought for increasing my visibility was to get a smoke system like air show planes have. I could let out a long stream of smoke as I approached the pack. Plus, it would make for a crowd-pleasing checkered-flag finish line drama. I had that thought about three years ago, but it’s no simple thing for a certified airplane to get a smoke system. There’s a lot of paperwork with the FAA. I hounded my mechanic about it for about a year and a half before he caved and agreed to take it on. But then, when we got into the nitty-gritty of it, the smoke oil tank couldn’t be installed under the baggage compartment floor like I had envisioned. It would have to be above the floor, where it would take up nearly half my storage. As much as I wanted to be able to say, “Smoke on!” it was too much of a sacrifice of Tess’s utility. And then, of course, we had our long-running series of serious maintenance headaches, breakdowns, and groundings, and I haven’t been racing much, so I hadn’t been thinking about it.

Until the other plane passed by me as unseen as a ghost plane.

Of course, we fly with flashing strobes on our wingtips and our landing lights turned on. Modern landing lights are super-bright LEDs that use precious little power and, unlike traditional light bulbs, last pretty much forever. That makes us more visible. But there’s a way to take it up a notch, and that’s the charmingly-named Wig-Wag.

A Wig-Wag controller turns your landing light system into an aerial discotheque. Only, you know, without the music from the Bee Gees. So with the plane down once again, and with plenty of time on my hands, I started researching Wig-Wags and was pleasantly surprised to quickly locate one that was actually pre-approved for our airplane. It’s called the MaxPulse, and it’s a simple solid-state control switch that gets spliced into the wiring between the lights and the master switch. It’s surprisingly affordable, as airplane stuff goes, and my mechanic thought the installation would be a breeze, as airplane stuff goes.

All things being equal, it seemed like cheap insurance, so I said, “Let’s do it.”

The MaxPulse, once installed, will let our landing lights still work as landing lights at night, but during the day there are four different options:

Both the landing lights, which are mounted in the leading edges of Tessie’s wings just inside her racing stripes, can flash at the same time like giant strobe lights. Poof. Poof. Poof. Poof. Forty-four pulses per minute.

Or they can wag back and forth. Left one on, right one off. Right one on, left one off. This is officially called alternating, but in the common tongue, this is our Wig-Wag. It really catches the eye in the air. Poof. Piff. Poof. Piff. Also at forty-four pulses per minute. Or….

It can wig-wag at eight-eight pulses per minute. Poof-Piff-Poof-Piff. Or…

It can wig-wag at one hundred frickin’ twenty pulses per minute. PoofPiffPoofPiff.

We’ll have to experiment to figure out which option makes our speedy slow racer the most visible, but there’s no doubt that we’ll be able to light up the day.

It’s not smoke, but it’ll do.

Weighty options

Posted on March 29, 2019 by admin

I let go of the yoke. One heart beat… Two heart beats…

The horizon rises in the windshield. Slowly at first, then faster. Up. Up. Up. Faster and faster still. The whisper of the wind turns into a roar. Then a howl. Twin tails rising high into the air, Tess nose-dives toward the earth like a Stuka dive bomber.

The wind resistance tugs at the prop, red-lining the tachometer. The vertical speed indictor shows 800 feet per minute down… 900 feet per minute… 1,000 feet… 1,200… The airspeed indictor snaps to the yellow line. I lose my nerve. My hand back on the yoke, I pull back. Gently. Firmly. The horizon, now above my head, slowly slides across the roof of the canopy, down the windshield, below the nose. We are straight and level again.

I turn to Lisa, who’s sitting calmly in the right seat, pencil poised over her knee board. “Well,” I say, “that wasn’t encouraging.” Clearly the new trim is not working right.

So much for a trouble-free return to service.

We return to the field, land, and my mechanics make an adjustment. Back to the designated practice area. Back up to 8,500 feet. Again, the Stuka dive.

We return to the field a second time, land, and my mechanics make another adjustment. Back to the designated practice area. Back up to 8,500 feet. Again, the Stuka dive.

On the third try, we’ve run out of trim. It’s deployed 45 degrees into the slipstream, and still the elevator can’t hold the plane in level hands-off flight. Something is seriously amiss. Tessie has become mysteriously nose-heavy. Like our engine mystery of two summers ago, there’s no satisfactory and satisfying answer as to why this is so. But cause aside, we need a solution. And one solution to a nose-heavy airplane is to simply add some weight to the other end. And as the tail is much farther behind the center of gravity—that magic balancing point an aircraft in flight rests on and rotates around—than the nose is forward of the center of gravity, a little weight should go a long way.

Or so we thought.

Funny how many of the things we think should work simply don’t with this stubborn little airplane.

I won’t bore you with all the details of the testing plan. Or with the details of the flights, one after another, after another, after another, after another. For most of a day. But we started by securing one-pound bags of “Sea Pearls” in Tessie’s tail. The bags are designed for scuba diver belts. They are small, flat, full of tiny lead shot, and surprisingly heavy for their size.

Based on the weight and balance sheets, it shouldn’t have taken too many bags to get Tessie to fly right. The weights were placed 180 inches behind Tess’s center of gravity. One hundred and eighty inches is a loooooong lever with which to raise the nose. Or so we all thought.

But it was not the case. Seventy-five dollars’ worth of Sea Pearls later, I still had a plane the Luftwaffe would have been proud to deploy. With the maximum amount of added weight that my maintenance team felt was safe, we still couldn’t fly level. Oh, sure. It was better. The dives were slower. Less aggressive with each bag of Sea Pearls. But anything like level flight with neutral trim eluded us.

It was time for Plan B. Which was four washers installed along the bolts that secure Tess’s tail to her fuselage. Yep. We shimmed her tail. Then I went up to test fly.

No more Stuka.

But were the weights still needed? There was only one way to find out. Take some out, test fly, and see how many, if any, were needed with the shimming of the tail feathers. Again, I won’t bore you with the details of the flights. One after another, after another, after…

But in end, there were no Sea Pearls in Tessie’s tail and she flew true.

In fact, she’s never flown better.

Now, if we can just figure out why her brand-new attitude indictor is spinning like a top, and why her compass points the wrong way…