Gallery/Lance Camp­bell’s Amaz­ing Lock­heed SR-71 Black­bird

The story be­hind this RC project that took nine years to com­plete

Model Airplane News - - CONTENTS - By the Model Air­plane News crew

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.

Pos­ing on the Top Gun run­way, Lance Camp­bell, with his Lock­heed SR-71, shows off his im­pres­sive awards.

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.

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.

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.

Lance also scratchde­signed and built his own scale land­ing gear. All six main wheels have their own in­de­pen­dent disc brakes.

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