Gallery/Lance Campbell’s Amazing Lockheed SR-71 Blackbird
The story behind this RC project that took nine years to complete
The story behind this RC project that took nine years to complete
At the 2017 Top Gun Scale Invitational, there were many amazing aircraft flown by some of the best pilots in the world. One of the standouts on this year’s flightline was an unusual aircraft in the form of a Lockheed SR-71 “Blackbird” that was totally scratch-built by first-time Top Gun competitor Lance Campbell of Columbia, Missouri. Lance did an amazing job and earned second place in the Expert class. The Blackbird scored an impressive 99.167 static points, and at the Top Gun awards banquet, Lance also received the Engineering Excellence award, sponsored by Robart Mfg., as well as the Critic’s Choice award, sponsored by Zap Glue and Model Airplane News. Using Futaba radio gear, Lance flew the SR-71 to a total flight score of 195.709 points. The 85-pound SR-71 is 13 feet long and is powered by a pair of JetCat 140-RXi turbines.
After the competition, we had a chance to catch up with Lance to get the inside story on his amazing award-winning and super-smooth-flying Blackbird.
Model Airplane News: Why did you choose the SR-71 for a project?
Lance Campbell: To be honest, the moment I decided to do it, I wasn’t expecting it. Quite a while ago, I was really interested in doing a Ziroli B-25. I planned a trip to the Wright-Patterson Air Force Museum [National Museum of the United States Air Force] in Dayton, Ohio, to gather documentation photos to start the project. When I toured the museum, I first saw the SR-71 in person. As I looked at the SR-71, I was just struck with the notion that this was too cool of an aircraft not to do—and to try to do it justice as accurately as possible. There was also an appeal to try to do something unique. Even today, you can count on one hand the people that have done a scratch-built SR-71 and made it to the flying field with it.
How did you develop your plans?
I started with a rough set of plans but soon realized that much of it was incorrect. I retained around 10 percent of them. As I dug deeper for reference materials, I made a few initial contacts with people involved with the real program. I developed a positive cycle in that, as the project progressed, some in the full-size community saw my sincere effort and started to provide materials to help the project along. Then I’d publish further progress on my build blog, and follow-on materials would show up. By this time, I had visited about six of the planes in various museums and taken several thousand photos as well.
This might be hard to believe, but the plane was built with no plans. I had a rough outline and core dimensions, but ultimately I needed to carve nearly the entire thing to shape. Using composite plugs and molds meant that the first shape being made was a fully solid object that needed to perfectly match the shape. Internal formers and equipment placement would come later and was not relevant at this stage. That’s not to say that I didn’t scrutinize every dimension and angle dozens of times to cross-reference them against Lockheed schematics and all the photos. When the shape was as correct as I could possibly make it, I used lasers to assist in laying out the hundreds of panel lines and corrugations. This way, I could properly place panel lines across compound curves.
With the plugs done, I cast fiberglass molds over every part. This was my first time trying any of this. Prior to this project, I had never done any significant fiberglass work and never made a mold at all, but I was always curious to learn. When the prototype was laid up in the molds, I could then start making the traditional model formers to carry the model’s components and provide the needed structure. I couldn’t do this until this late state because I had to take into account the thickness of the skin of the airplane. So, in some ways, it was like making the plane from the outside and progressing inward.
How long did it take to produce your prototype?
Initially, I thought this was [going to be] a fouryear project. Boy was that wrong! It took three years to make the plugs (doing the panel lines and corrugations was a year of that time). Then I spent two more years to make the molds. Then another two years to make the first prototype, including all the internal former design work and development. So it was seven years before the prototype flew.
Speaking of the prototype, I designed it from
“I THOUGHT THIS WAS [GOING TO BE] A FOUR-YEAR PROJECT. BOY WAS THAT WRONG! IT WAS SEVEN YEARS BEFORE THE PROTOTYPE FLEW.”
“IT REALLY TRACKS AND FLIES LIKE IT’S ON RAILS. LIKE THE FULL SIZE, IT’S BUILT FOR ONE THING: TO GO FAST IN A STRAIGHT LINE. THE MODEL DOES THAT BEAUTIFULLY.”
the beginning to be flown in private and to be a test mule. I spent an entire summer flying it (using model-airplane engines and propellers) and slowly adding one system at a time, getting the bugs worked out. It was never going to be painted, and I could hack holes in it where I needed to try different things as part of the test-flight program. Armed with those results, I spent the next two and a half years to use the existing tooling to finish the show plane and start flying it in public.
What was involved to design and build the landing gear, and how long did it take?
Along with mold making, I was also interested in machine work. I used the excuse of needing landing gear to purchase a milling machine and a lathe and teach myself about metal working. It is great fun and not too bad to learn. During the last two and a half years of building the show plane, I spent about a year making the landing gear. The wheels and brakes were developed by Glennis Aircraft, and the retract mechanisms are Tom Cook’s Mk 30 units, which work great.
The biggest development part was starting with the correct spring that would give me the proper travel and compression strength and then designing the strut and gear around it. That way, it would sit properly on the ground, rotate correctly, and touch down properly on landing.
What materials did you use in the layup of your parts?
Since this whole process was new to me, I made the prototype stronger than it really needed to be. I laid it up with two layers of 6-ounce S fiberglass cloth, with 6-ounce carbon cloth in areas of high stress. For the show plane, I lightened that to two layers of 4-ounce S fiberglass cloth and 6-ounce carbon cloth in areas of high stress. That change alone lightened the show plane by 12 pounds from the prototype’s weight. I also made plugs and
“I USED THE EXCUSE OF NEEDING LANDING GEAR TO PURCHASE A MILLING MACHINE AND A LATHE AND TEACH MYSELF ABOUT METAL WORKING. I SPENT ABOUT A YEAR MAKING THE LANDING GEAR.”
molds for the four integrated fuel tanks and laid those up with Kevlar cloth.
For the show plane, knowing the black plane would get quite hot in the summer sun, I did the layup with a high-temp resin from Resin Services, which also supplies some of the resins used by some NASCAR racing teams. The resin I used is solid to 325°F and does not require a post cure. It just cures at room temperature, but it does take a couple of days to get to its full hardness.
What are the SR-71’s flight characteristics like?
It flies great. After so many years on a project, you set a pretty high bar on how well you hope it flies. Even with those high expectations, it flies even better than I could have imagined. It really tracks and flies like it’s on rails. Like the full size, it’s not an aerobatic plane, and it’s built for one thing: to go fast in a straight line. The model does that beautifully. Like the full size, it does not turn in a short corner, either. It takes about a thousand feet to do a 180-degree turn with the model when at flight speed, but then again, the full-size bird would take two states to turn around in, so it’s all relative.
For slower flight and in the landing circuit, it’s really predictable and well behaved. The real bird has some very complex things going on in the outer wing panels, which have a very unique droop in them. This helps with an equivalent of washout that we are familiar with in our models. I was so worried about getting these outer wings correct in this droop, so I made them as separate plugs/molds. If the plane did not behave correctly in flight, I could redo these outer wings to address it. Turns out, I got the droop spot-on, and the plane has all the good characteristics you want: predictable low speed and high speed that tracks dead-on straight, without a click of trim’s difference between them.
Do you have any comments on being successful with a project that takes years to complete?
Something like this really just takes as long as it takes. It is a hobby after all, and the build process should be fun in its own right, without pressure to get it done and to be at the field with it before it’s finished. To stay motivated, I really focused on just the next stage of the build and did not dwell too much on being done with it, as that part sorts itself out eventually. I hope that others see a project like this and are encouraged to tackle their own planes that they would like to do, even if they are a bit off the beaten path.
For more photos and information go to ModelAirplaneNews.com/SR71.
On takeoff, the ring of LEDs shows up well, simulating an afterburner departure. And just like the full-size Blackbird, Lance’s SR-71 uses a 42-line ribbon drag chute to shorten the landing rollout.
This photo, taken during the static judging, shows just how big Lance’s aircraft really is.
From this angle, it is impossible to tell the model from the real thing.
Talk about scale! The pilot and RSO (Range Safety Officer) are wearing the proper David Clark space suits. The front instrument panel is detailed with every knob, switch, and gauge.
With the hatch removed, you see just some of the equipment onboard the twin-turbine-powered Blackbird.
This photo shows the hot end of the Blackbird, with its double-wall thrust tube and the LED ring that simulates afterburner function.
Here’s one of the distinctive inlet spikes. It’s angled slightly down and inward, just like the full-size Blackbird.
Posing on the Top Gun runway, Lance Campbell, with his Lockheed SR-71, shows off his impressive awards.
Lance also scratchdesigned and built his own scale landing gear. All six main wheels have their own independent disc brakes.