Hurricane Opener

Text and photos by Budd Davisson, Air Progress, April, 1975

Little Big Wind from Puyallup

It's a cliché, a terribly overworked way to begin a pilot report. It usually runs something like, “…as I rolled back to level, my finger inched up to the trigger on the stick. My eyes narrowed to hawk-like slits and my body ached from the excitement of the hunt. Then, there it was, the hapless enemy centered in my gunsight. I . . . " ad historium, ad heroium, ad nauseam. This fighter pilot scenario has been played out in the opening paragraphs of pilot reports more times than it was in the whole of World War II by both sides combined. But damn the clichés! As I rolled over on my back and came screaming down in an overhead gunnery pass on the unsuspecting Pitts, I did feel like a fighter pilot. And when I looked out at my wings, I wasn't seeing a neat new piece of Wichita sheet iron pretending to the throne of fighterdom. I was seeing green and brown wing panels with cannon stubs protruding from the leading edges and British roundels on the upper surfaces. Who cares if the panels were only five-eighths the size they should have been and the cannons were aluminum tubing and wood? It looks like a fighter. It flies like a fighter. So, as far as I'm concerned, it is a fighter ... in the small, easy-to-manage size.

Fred Sindlinger of Puyallup, Wash., probably wasn't ready for the stir his Hurricane has caused. In his debut at Oshkosh, he taxied around with a fuzzy little herd of Hurricane groupies trailing after him. In the air, you could almost see airplanes around him stop and scratch their heads as he went blasting past. At least once every ten minutes one of the conversations on the fringes of your attention would begin with "Hey, did you see that little Hurricane? Far out!"

Far out is hardly strong enough The first time I caught sight of Sindlinger's little plywood Hurribird I almost swallowed my gum. I was at Oshkosh, peering out of the cockpit, trying to avoid performing an unnatural act on any of the 21 other airplanes in the pattern. I suddenly caught sight of this familiar looking hump-backed silhouette far out on the edges of the bumblebee swarm. Holy whatever! It's a Hurricane! I'd never actually seen one, but no model-building warbird buff could mistake those lines.

I only got a glimpse of the camouflaged form before I had to return to the task of threading my way through the maze to the ground. Then, for several hours, I saw nothing land that even remotely resembled a Hurricane, so I decided the pressure of the flyby pattern was getting to me. Not only was I beginning to see spots, but now the spots had wings and were camouflaged.

Hurricane side
From the side Fred pretty well nailed the profile

The next day it happened: Fred Sindlinger taxied off the runway and rolled past me. I'll have to admit that watching that little taildown hustler taxi past pretty well crumbled my carefully contrived image as the blasé writer type. That thing was so incredibly cute that I dog-trotted after it right along with the tourists. The airplane had its effect on everybody at the fly-in, and was voted the best replica. Its innovative retractable gear also won a prize for engineering.

In the strictest sense of the word, Sindlinger's Hurricane isn't really a replica, nor is it a scale model. In the world of modeling it would be known as a "stand-off" scale airplane because if you stand off from it a bit, it looks dead accurate. But if you were to lay a tape measure on it you'd find certain dimensions have been altered and details omitted. Big deal! The purists may rant and scream about the flat engine or canopy modifications; they can go stick it in their hats. Certain things just don't scale down—pilots and Merlin V-12s, for instance. Working with the goal of an airplane that is both easy and fun to fly, Sindlinger has done an absolutely incredible job of duplicating a Hurricane in five-eighths scale.

Why a Hurricane? To some it would seem to be an unusual choice, if only because it's the ugly duckling of its peer group. Parked next to a Spitfire or a Messerschmitt, a Hurricane looks huge and misshapen, a hump of steel and fabric next to finely shaped projectiles of aluminum. Its borderline homeliness is one of the reasons Sindlinger chose it; it would be unique. But more important, the Hurricane offers the best combination of lines and areas that can be scaled down to carry a pilot and a Lycoming engine.

The original Hurricane, filled the gap between the last biplane fighters and the first highly-loaded superships. It had the design features of the later airplanes (retractable gear and basically clean lines) combined with the docility and handling characteristics of the older biplanes. Its areas were big, its lines long; that's a combination that can't be overlooked.
When you start scaling an airplane down, you're really stepping into a bag of gopher guano. The big problem is areas. When you are working with wing area, for instance, you can't just chop the span and chord to make a scale-shaped wing. If, for instance, you want a half-scale model and you cut the linear dimensions in half, the area turns out to be only a quarter of the original. It's a squared function; an eight-tenths model has 64 percent of the area. This applies to taiIs and everything else.

When you start trying to do a weight and balance on the scaled down version, you find that the man is suddenly a much greater percentage of the gross weight. A pilot can represent well over half the moment of a flat engine, so you wind up having to slide him forward, which ruins the looks of the airplane.

Also, a man is not an area, he's a volume, a cubic function. If you cut the cockpit dimensions by half, you only have one-eighth of the volume to put him in! So, unless you're willing to go on a crash weight-loss program that would begin by amputating your arms and legs, you're stuck with certain minimum dimensions for the pilot.

The Hurricane represented the best solution to these scale problems. It was big of area and cavernous of volume, so when it was scaled down, things didn't have to be juggled much at all to make everything work.

The original Hurricane used steel tubing and fabric for the fuselage and fabric for the wings. The wings were eventually modified to aluminum, but the fuselage remained fabric covered from the cockpit back.

Sindlinger has retained the construction appearance of the later Hurricane, but his airplane is wood throughout. The fuselage is a wooden truss, fleshed-out with stringers and frames. The frames are unusual. Instead of the usual plywood, they are laminated of four and five layers of spruce strips, curved to the exact shape of the fuselage cross section. From the cockpit forward these frames are skinned with plywood, forming a stressed-skin box. From the seat back the truss/frame combination is fabric-covered.

The wings too are all-wood and stressed ski n. The ribs are standard built-up truss types and the spars are beefy-looking box affairs. The landing gear mounts in the wide center section and retracts through a really clever system of screw jacks and fulcrums driven by a hand crank in the cockpit. The landing gear js so efficient and simple that Sindlinger offers plans for the. gear separately to any who want to adapt it to their own designs.

Sindlinger engineered, tested and built the original structure himself, digging as much engineering data as possible out of every known source of info on wooden aircraft structures. Then, when the near-riot he caused at Oshkosh convinced him to go into the plans business, he turned the entire airframe over to two professional engineers who went through the structure and gave their blessing to Sindlinger's prototype. These same two prepared the drawings for the plans, which rate high in quality and professional appearance.

At present, Sindlinger himself will supply only the retracting screwjack and block for the landing gear, plus the plexi windshield and canopy. Sparcraft Mfg. of Tacoma, Washi ngton, is setting up jigs for various wood components and Stolp Starduster Corp. of Riverside, California, is geared for supplying all the 4130 steel fittings and AN parts. By the time you read this, Sindlinger will have a plans modification that eliminates the 4130 fittings and replaces them with aluminum so the home whacker can whittle them out himself.

Hurricane Break
You have to look hard to realize it's not the real thing

How does it fly? How else could it fly? But the first time I approached Fred about doing the pilot report number on his airplane, he was reluctant, and understandably so. He had just flown off the restrictions and wasn't about to get it bent up by some type-hungry guy he didn't know from a kumquat. That was a couple of years ago. Now that he's gotten to know the airplane a little better and had plans and plenty of jigging to build another, he was a bit more receptive to playing Hurricane roulette with the formidable Air Progress evaluation team (me).

The workmanship on Sindlinger's own airplane is something right out of an 18th-century French provincial cabinet shop. Even on the inside, where all the wood is'finished in its natural color, it flows together so well that it's hard to believe it's made from many different pieces of wood. The canopy and its painted stripes at first distract your eyes as you try to peek around them when taxiing, but in a few minutes you don't even know they're there. And if they bug you, you can always slide the canopy back.

My checkout was simple enough. I sat in the cockpit while Fred told me how many cranks it takes to get the gear up (19) and how many notches of flaps I need to land (two or three). He then said goodbye, pulled a rosary out of his pocket, and did his best to appear calm as he stepped back to watch.

Taxi and. runup were no different from any other airplane except you don't often find a 150 Lycoming with a constant-speed propeller to check. Because the flaps are of the split trailing-edge variety (the bottom of the wing hinges down and the top doesn't move) I only hung out one notch of flaps before swinging out onto the runway.

My initial impression of the airplane had been that it was a fairly heavy bird, but the acceleration and quick liftoff told me that appearances are deceiving. With a gross weight of only 1375 lbs and a wing area of 102 square feet, it· gets off in only about 500 feet. Except for the initial distractions of the windshield framing, the takeoff was about as straightforward and uneventful as a takeoff could be. The rudder/tailwheel linkage has a nice quick feel without that twitchy oh-my-God sensitivity of so many homebuilts. This kind of feel is important on an airplane this size, because too much control is just as bad, or worse, than not enough. An overanxious pilot can aggravate a little airplane's natural tendency to do things fast.

"Ten, eleven, twelve." I heard myself saying during initial climb out. I wanted to make certain I knew how many turns it took to bring the gear up so I'd know definitely how many to get it down (there/s no indicator in the cockpit to help you). As it turns out, you just crank until it won't move anymore, and that's it.

The initial rate of climb is fantastic. I timed it at around 1750 fpm, which puts it up with a two-hole Pitts and far ahead of any production airplane I can think of with 150 hp.

The second the wheels left the ground, I knew I'd like the control feel. It's quick enough to make the average pilot feel like he's flying a fighter, yet not so quick and sensitive that each heartbeat sends the airplane into convulsions. The roll rate is good but not lightning-fast, and it responds immediately to aileron deflection of any kind. In short, there's no doubt that you've got complete control over the airplane.

Hurricane up
Is that cute or what?
Up in Wisconsin the landscape looks like a patchwork quilt belonging to an engineer's wife; every bit of land is perfectly square and a mile on a side—perfect for finding out exactly how fast this pint-sized fighter really flies. I cranked over into a 60-degree bank, ripped down to 1000 feet AGL, and set up 75 percent power. lining up with a road. I checked my watch and zipped over three sections of land in a minute, so I kept on going and timed the next three exactly. I repeated the process in the opposite direction and began fiddling with the computer I'd brought along. At that power setting we were tooling along at a solid 183 mph. Later checks at other settings showed 170-175 at 65 percent, which Sindlinger says is good for over 26 miles per gallon at 6.5 gallons per hour. The five-eighths Hurriplane showed its stuff in the Paz many efficiency contest by hitting a maximum of 197 mph and a low of 55.

Pulling up hard, I watched the landscape below fall quickly behind, tilting on its side as I chandelled up for altitude before I let the natural urges of a pilot in such an airplane run wild. Craning around, I peeked behind me as I turned and climbed through a 360-degree arc. When I had 3,000 feet I steepened the bank past 90 degrees, brought the power back and dived down for speed. Loop! Big and easy with just a touch of torque on the top and bit too much on the bottom. In my peripheral vision the green and brown below played games with the similarly-colored wings. I added to the confusion with a roll, followed by a four-point, then an eight. Then, as the speed began to bleed off, I pulled up into a hammerhead to try it all again. Sometimes I don't know how I can stand to do this sort of thing for a living. (Ed note: I was a smart little sh*t at that age, wasn’t I?)

The stalls were no surprise; sharpish with a bit of wing drop and immediate recovery. The spins were equally predictable What was surprising was the landing. I had dirtied up for the stall series, so rather than crank it all back in again, I came into the pattern with the gear out. On downwind I ran a crank check by hooking a couple fingers over the gear handle and tugging to satisfy myself that it was really down (a red mark lines up on the sprocket and chain as a double check). Gear down, it sinks like a Cherokee, so I flew a tight pattern, dropping a notch of flaps on each leg, giving me 30 degrees by the time I got onto final.

Visibility over the nose is as good as a tri-gear all the way down to the flare and, since I had decided to wheel it on, none of the runway ever did disappear. Things were going perfectly. Then I felt that feeling that said "Uh-oh. I'm a foot high with nothing to fly on." Gaboing! I got a neat little bounce for my inattentiveness. It's getting embarrassing to write about these airplanes and always ending by saying that I blew the landing. But let's face it: I blew the landing.

A touch of power kept the after-the-bounce jitterbug to a minimum and I taxied over to give the airplane back to a very relieved Fred Sindlinger.

Something has to be said about Sindlinger. He's a pro. A quietly professional homebuilder who's not going to hype you with a sales pitch or stretched numbers. I found everything he says in his brochures to be conservative. He has tested everything he does and has it all engineered. Don't let his quiet exterior fool you.

The original Hurricane was Britain's backbone during the smoke-filled days and fire-filled nights of 1941. And, although she wasn't as pretty nor as famous as her comrade-in-arms the Spitfire, the Hurricane did a job that had to be done. Fewer than a half a dozen still exist, but Fred Sindlinger has given us a chance to remember, a way to build a little bit of nostalgia all our own. As soon as this whole replica warbird thing really gets going we're going to re-enact World War II—in five-eighths scale, of course.

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