Designing and building an actual flying airplane specifically for a motion picture is not something Hollywood does very often. Owing primarily to its long lead time and, of course, expense, today’s digital-rich movie making world makes even large-scale flying models very unlikely. Still, flyable airplanes have been created with success. Hindenburg was flying when this futuristic – looking monoplane (right) was built and flown for “Things To Come.”
At least since the death of famous movie stunt pilot Paul Mantz in the cobbled-together “Phoenix,” our litigious society would rate any modern scratch-built venture a high risk. Indeed, some of the airplanes invented for movies might well have taken out a pilot or two had a flying prototype been built from the art director’s plans. Where would an engineer have put the structure to support the rotor in this interesting fantasy by Brooke “planned obsolesce” Stevens?
“ZRS” the movie faces the further problem (some say opportunity) that the “airship’s fighter” had only been drawn up, but never built.
Author Rowan Partridge had envisioned the Army’s experimental Bell XP-77 has having its problems ironed out to become the airship’s defensive fighter (Rowan’s work, right). Largely of wooden construction and shaped a bit like the Hughes racer, an evolved version might well have been fast and highly maneuverable. This is based on sound history, since the first monocoupe construction airplane, the “Cigare,” was largely wooden construction. (Footage of a similar airplane was seen in the 12th chapter of the “Captain Midnight” serial, below). The mostly wooden de Havilland “Mosquito” was a WWII legend, and still appears at airshows today, 75+ years later. The Army-Navy procurement system could sometimes agree on a basic airplane so as manufacturers could build the two versions on similar assembly lines. (The SBD is a good example; its Army version was the A-24.) While the literature shows no Naval interest in the Army prototype XP-77, it is certainly not impossible. The Army-Vought V-143 was seen as carried in the Goodyear ZRCV design. An existing Army design was a more realistic idea than expecting both airship and purpose-built airplane to be scratch-built for each other at the height of the Great Depression.
Nonetheless we elected to finish out BuAer Design #124 that was on the drawing board when Macon went down. The elliptical wing was #124’s signature, and we investigated the possibility of investing in and modifying a mini-Spitfire kit. One of the mini-Spit kit planes has been criticized for not having the right overall appearance, the scale of the wing seeming to not match that of the fuselage. For a time we drew “razorback” versions of the mini-Spit’s kit fuselage where the mismatched scales would be disguised. NAA volunteer artist Bo Watwood drew up a three-view.
Trouble was, in model form, it winds up looking like a Spitfire, and not like #124 at all.
Since #124’s profile is clearly P-40 Warhawk-like, we welcomed the news that a kit plane builder was going to make both a mini-Spitfire and a mini-P-40 kit plane.
Once we jammed the Spit’s elliptical wing on the Warhawk fuselage, we had BuAer #124 in the flesh – or, at least, plastic. But, would it fly?
Since the producer, his family and many friends are EAA members and aviation enthusiasts, we are determined that an actual airplanes will play the roles of the novel’s hook-on defensive fighter and bomber planes. SBDs are still flying, so can be rented. Since no fighter exists, there is only one way to be sure a pilot-sized mock-up and CGI stand-in is not quickly substituted for this long-lead-time essential. And that is to have a real airplane available when the cameras start rolling. Quite a bit of time was spent mulling over how not to kill ourselves (literally) cobbling together a composite machine that could fly – and not wind up like Paul Mantz. So first off, we had to know the idea was airworthy.
Luckily we have former Shuttle technician, r/c modeler and kitplane builder Mark Shimei on our team. Mark (left) re-engineered a P-40 and a Spitfire foam-electric kit to work together and ta-da! BuAer #124 flew for the first time. As you see in the video, Marc’s creation flies very well, actually. Too bad all the hook-on pilots were long gone and never got to see it.
So now all we had to do was raise funds to be ready to negotiate with the kitplane manufacturer for a fuselage from one… and wings from another. As fate would have it, neither kitplane ever made it into production.
Through another Shuttle alum we became aware of the story of two talented designers, the Strieker brothers of Germany, whose world-class model airplane creation had won many competitions. Their friends had told Thomas and Matthias that their model airplane seemed the perfect candidate to be scaled up to carry a pilot. So they did! Partnering with Silence Aircraft, a German sailplane maker/carbon-fiber experts, the team created the “Twister,” the hottest little airplane to come into the kit world in many years.
When we read about it, the solution seemed obvious. With a wingspan identical to the Sparrowhawk, a Twister could play the role of the novel’s P-77 airship’s defensive fighter airplane. We were already mentally redesigning the modern bubble canopy and fancy tailwheel pant as we set about trying to obtain a kit. One kit had been sold in the Pacific Northwest though a US dealer. It was said to have been built in in a seemingly reasonable amount of time. That Twister made an appearance at Oshkosh AirVenture one year.
The kit’s U.K. importer, Zuluglasstec, became an early and enthusiastic customer. Peter Wells started flying all over Europe (seen here at where else, Friedrichshafen). Peter soon constructed a second Twister, and won a contract to fly them for SWIP on the European airshow circuit. Very exciting downloads of Peter and partner pilots stunt flying are seen on the Zuluglasstec site, the Silence website, and other web locations.
After years of indecision, we finally bit the bullet and purchased a Twister kit. Serial number 006 arrived at our home in October, 2011, as complete as could be ordered – with the Jabaru engine prep included. Since BuAer Design #124 was to have pit-pin landing gear, similar to the beaching gear of a seaplane, we elected to have the retractable gear option. As advertised, we found complete structural assemblies molded from a carbon – nomex sandwich, while the pilot is protected in a Kevlar tub. It took us a while to do the parts inventory and study the construction manual.
The wings section is first in the Twister manual, and we opened our assembly log on October 19, 2011. That step glued in the first of two pin support ribs inside the flap assemblies. We quickly became aware of how much we had to learn, since this kit was not for beginners… or those faint of heart. We found it helpful to make all sorts of GSE (ground support equipment, or in some circles, Get Somebody Else) to hold the assemblies as required, most important an adjustable fuselage stand.
One poly gasoline tank is glued in each wing after applying copper tape to envelope it a Faraday cage. Navigation lights (sort of LED strobes) are cast into tip shapes and are glassed into each wing tip. There were some opportunities to improve the wording, illustrations and step order in the wings section of the manual, and we were delighted our suggestions were incorporated in a new 1.6 version of the wings manual.
Peter Wells has been instrumental in adapting details of the Twister to comply with UK aviation regulations, and has created several innovations to improve the Twister, some of which had been added to the manual. We incorporated these except the gear/flap/throttle position warning, as we foresaw installing one of the new “glass cockpit” combination flight instruments, eventually deciding on a Dynon Skyview.
Designing a fuel system that would draw gas from and put it back into the same tank centered around a duplex selector valve. Other homebuilders had suggested an electric selector valve, which we adapted to the Twister’s sloping underside. Pre-filters protecting the valve obviously had to be accessible, so are mounted above the access panel recommended by the factory. The interface mates the formed fuel tubing to the flex lines running to the detachable wings.
Sun N Fun visitors helped us to early test-fit the wings so the prospective pilot could sit in the cockpit and make airplane noises. Year and a half later all major assemblies, plumbing and underside wiring had to be complete because Access would be very restricted after the one-piece fuselage base was glued into place. We enlisted six helpers to simultaneously mix and apply flox to the large assembly and ratchet-band it in place. The base was molded with carbon reinforcement to spread the landing gear loads to the wing spar box.
The factory introduced a major modification by integrating the tail wheel mount on the rudder post plumb line. We purchased the new rudder and other parts to incorporate this improvement, since it is supposed to help the ground handling – and it fits in with the overall appearance we seek to play the role of BuAer #124. A European team has completed the first kit with the new tail wheel; ours may be the first to fly with the new tail and retractable gear.
The smooth appearance of the tail group decries the tight interior component design that makes it work. It is a clever juxtaposition of carbon-reinforced push-pull rods, movable control hardware and locking features that insure all the removable pieces stay there during flight. We were a bit nervous about crimping the rudder cables because there is no provision for adjustment, but we got ’em okay.
The manual suggests where to cut access in the fuselage, but doesn’t detail how to re-attach what is removed. We have been building up new structure edges, drilling, tapping and installing inserts that should last the life of the aircraft. We found ourselves adding two hatches aft of the firewall by installing machine screws and inserts. We also used this technique to replace the few wood screws provided. Somewhere in that second year, the US dealer quit business and removed anything to do with Twister from his website.
After months of sanding, filling and priming, painting day finally came. Our friend and neighbor Kirby, who restores Corvettes for a hobby, took on the two-part task with the rather tricky three-part paint that was recommended. We’re going for the sea-gray bottom and sky blue top used in some squadrons in WWII. For an appearance easier to be touched up on the big screen, we skipped the factory plan for wire antenna and strobe, incorporating an internal antenna and LED lights in nose and tail.
For us, Peter Wells manufactured and supplied his design for a greatly improved hatch hinge and latch design, which allows the canopy to be jettisoned, in flight if necessary. Meanwhile, we became aware that one of his customers, a U.K. homebuilder, had started a Twister kit about the same time we did. Andy is blogging about it at: silencetwisterbuild.blogspot.com in great detail. Andy has not only been a huge inspiration for us, but has helped us over some serious challenges during our build. We hoped to not be more than a few months behind his build, and he’s certainly going to be flying months before we are.
As supplied with the kit, the electrical wiring harness was about 40 percent complete. The factory sold us their upgraded landing gear and flap motor drive switches, harness and connectors. We assigned the original smaller-gauge harness portions new jobs, using the “Aero-Electric Companion” as our guide. The instrument panel was to be made from an included fine plywood sheet. We elected to made a carbon two-part panel, allowing the power portion to be firmly mounted and the upper portion to be shock mounted. We used CAD extensively – that’s Cardboard Aided Design (photo).
The kit allowed freedom to create our own transponder, transceiver and engine interface shelf in the ample space forward of the instrument panel. All electrical work was scrutinized by our eagle-eyed Australian inspector, Chipper MacLeod (photo). We chose a rather unconventional piece to create the ground forest, so it could double as the firewall seal for the large hole necessary to pass the UL engine’s ECU connector. Also free to decide what battery to use and how to mount and wire it, we hopefully do not have too much weight forward with our carbon battery box right behind the firewall.
Prior to engine mounting we assembled the airplane for a full electrical and control test, pumping gasoline through the plumbing while optioning tanks and running the gear and flaps. (The flap drive had to be removed and factory reworked.) Right in the middle of our testing, the US Navy blimp flew directly overhead on its way south to test some sort of huge antenna mounted on its topside. A good omen! At his point the Twister factory manual’s steps were all but completely worked.
After a wonderful visit to their Belgian engine factory, we had elected to install a UL 260 engine. Not much of the kit airplane’s prep could be used, but we found a shop that could make the needed mods to the mount. Another few months integrating the engine and we popped over to the Sensenich factory to watch propellers being made, and to order ours. They delivered our beautiful coated wood prop.
More than four years after beginning, the big day arrived… we strapped Twister to a sturdy tree and fired her up. It was still a few more months before the FAA ruled our paperwork was in order, and our test pilot took her aloft on 7-7-17. Hit the “play” icon with the sound up for a replay of that happy moment.
Further updates will be in the form of posts to this site.
Read on to ZRCV: The Giant That Almost Was
Consider the DVD The Flying Carriers
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