Flying the Thunder Mustang
Sit behind the huge Falconer V-12 for the ride of a lifetime in Dan Denney's modern, composite version of aviation's greatest classic, in one of Dave's most memorable test rides... full article
Experimentals have come a long wayIn 1984, I started a company to test prototype aircraft and do first flights on kit built aircraft. Over the last six years there has been a real change in the methods and technology in the experimental movement. In years past, it was not unusual to argue with a KR2 builder to replace the wing bolts with AN hardware and have him complain about the extra cost involved with AN versus hardware bolts. Nowadays, it’s more common to ask the builder to add an old style tach or oil pressure gauge to his glass cockpit digital display. Even though you can download data after every flight, it’s not as easy to spot trends and problems at a glance during initial test flights. Another trend is to put everything but the kitchen sink into the cockpit. On most first flights I’ll have several circuit breakers pulled to make sure I don’t get all kinds of bells and whistles that distract me from just flying the plane. Needless to say, its been an interesting and ever changing business. One project that really stands out from all the rest, is the Star Kraft. Not so much for the finished aircraft, as all flying aircraft are cool, but in their approach and execution of building this very large and complex aircraft. The Star Kraft is a carbon fiber/all composite, eight passenger twin engine aircraft with an extremely large cabin and the added safety of center line thrust.
I became involved in the project in 1994 when the structural analysis was done by Martin Hollman of Aircraft Design Inc. Martin recommended me as a test pilot and human factors designer to help with the placement of controls and systems during the assembly of the aircraft. This plane was not your typical prototype. The founders and primary investors of Star Kraft are both pilots and successful businessmen who have flown both certified and experimental aircraft for the past twenty years. They firmly believed there was a need for a new generation of corporate aircraft, one that would outperform turbo props and some jets. Roger and his dad Harold had their first introduction to homebuilts when they built a Lancair 360 to use for company travel. This worked out so well that they decided to build a larger airplane using the best technology had to offer. The design work was done with state-of-the-art CAD equipment. The stability and control profiles were calculated by renowned aeronautical engineer, Jim Phillips. With solid research data, they felt comfortable building the plug and making the first plane from production molds. Their plan was to sell kits to help subsidize the expense of developing the Star Kraft. As with most projects of this magnitude, it took on a life of its own. Roger researched the issues of building an aircraft this size as a kit. The FAA was threatening to crack down on professionally built airplanes. Eventually plans for kit production were abandoned but work on a production version moved forward.
Whenever possible, Star Kraft used the latest technologies such as the TKS leading edge anti-ice system. This is the system where the leading edge of the wing has thousands of microscopic holes and alcohol is weeped through to prevent icing. They incorporated lightning protection mesh into the molded composite parts to ensure IFR certification. M y personal favorite is the drive shaft. The Star Kraft uses a six foot drive shaft to power the rear engine. Just before the first flights, we did a vibration survey and had a real problem with the frequency matching of the metal prop, engine and drive shaft. Alignment was also critical and we needed to find a good solution. We tried an MT composite prop and had great results with the natural damping of the light weight composite prop. We still had a few frequencys that coupled between the drive shaft and the engine. After much research, we located a drive shaft from a calif. manufacture of carbon drive shafts for NASCAR race cars. It’s made of carbon fiber and weighs only 8 lbs versus 40 or so for the steel shaft. We had no more vibration problems and one big safety benefit. If the steel shaft ever broke or the coupling at one end failed, I felt that the tail of the aircraft could be knocked off from the slinging 40 lb shaft. If the carbon shaft fails it shatters and turns to dust leaving the structure intact.
Star Kraft's commitment to this project was really tested when I recommended that they move the project 100 miles to a bigger airport for test flights. This meant all the final assembly would be in a rented hangar 100 miles from home. At this point there were four people helping on the assembly and they all moved from beautiful Fort Scott, Kansas to the Motel Six in Topeka for a month.
My experience with pushers is they overheat and on the first flight that was true. With some tuft testing and help from Dan Bond, one of the key players in the Nemesis Formula One team, we got it all sorted out. We did have some trouble with oil temps on the TSIOL550 ‘s but I think that was due to the small oil coolers that RAM uses on the 414 conversions that they do and that we copied.
So how does it fly. Actually much like a 414. Because there aren’t any engines on the wings, the roll inertia is less and the pitch and yaw inertia is greater. This is a very big airplane and it takes awhile to get it going but it’s also a very clean airplane. When you fail an engine not only is there no yaw but it takes awhile before the airspeed even starts to decay. I found that the rear engine single engine performance was just slightly better than the front and that with the front engine you had to hold right rudder during climb versus no rudder change for climb on just the rear engine. Definitely user friendly with the exception that you really had to think to figure out which engine quit and be careful to shut down the correct one.
Up to this point, Roger had kept a rather low profile and concentrated on building and running his other business. To continue with the certification process required more investment. To attract investors, we decided to start showing the aircraft’s potential and flew the plane to the NBAA show in Las Vegas in September, 1995. After the reception we got there, we decided to move ahead and set some point to point speed records .
I brought the plane to my home base in San Carlos to prepare for the record flights. As the weather window we were looking for approached, we moved the plane to Hayward for the full gross weight take off. The 2600’ runway at San Carlos was just a little short at max. weight. On the way to Hayward we had one of those beautiful days in California with unlimited visibility and smooth air. We took advantage of those conditions to capture several beautiful pictures of the Star Kraft .
Being economically challenged, we wanted to get the most for our money and decided to set two records on one flight. The hardest thing about setting records is notifying all the parties involved and coordinating with all the ATC centers that you fly through. This needs to be done just before you launch because if you arrange for LAX center to record your time over a fix on Monday and then cancel and try again on Tuesday, the new controller will just say he’s never heard of you squawk whatever and go away. If that happens at the start of a record it’s no big deal but at the end of a really good flight, it could really bum you out. Anyway ATC was very helpful and all went smoothly. The center in ABQ even went so far as to fax me the schedule of the military operations for that week in their airspace so I could pick the best times to transit and get the best direct routing. The only trouble I had on the whole record flight was each new controller said “Starship 700SK” then I’d correct them to Star Kraft which always followed with “what's a Star Kraft” then I’d give them a little soliloquy on the Star Kraft. This was fun the first twenty or so times but did get a little old after awhile.
My route was depart Hayward and climb VFR to 17,500’. At Bakersfield, I’d pick up an IFR clearance and climb to FL250. The first record would be from Palm Springs to Phoenix, then on to El Paso, TX for a second record. The first leg we had a little cross wind and were still pretty heavy but 312.87 mph on 36 gph is not bad. The second leg was more aligned with the wind and we really got on the step for a speed of 346.47 mph After several more months of flight testing, Star Kraft will install Orenda “600” engines which should increase speeds by 100 mph.
And this is what the experimental movement is all about. To push new technologies into the real flight world and learn by doing. Then do what no certified plane can; 8-place pressurized comfort Phoenix to El Paso, at 346.47 mph in just 59 min. 30 sec, on 36 gallons of av gas. FMI Starkraft 316 223 1900 po box 190 Fort Scott Kansas
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