Meet Harry Combs, at 51,000 feet. "So we're cruising along," says the 66-year-old president of Gates Learjet, "right over Albuquerque, directly above the LA.-N.Y.-D.C. routes, and all these airline jockeys are asking the Center to assign them different altitudes. They're in clouds at 35,000 feet, and everybody's squawking, 'We're spilling martinis in the cabin.'

"We just sit back and smile. But finally I can't resist, and I key the mike:

"'Center, 263 Gulf Lima at Flight Level Five One Zero. For your information, sir, it's real smooth up here.'

Harry Combs does have something to brag about. He's not only spent the last five years developing the Lear 55, a $3.5 million corporate jet that flies higher than anything except Concorde and military planes, but he's also managed to write "Kill Devel Hill," a beautifully crafted biography of the Wright brothers that places their true genius in the perspective of aviation history.

"Most people," says Combs, "think the Wrights were" a couple of homosexuals. "Now I tell you something. When I was a young man, I was plenty interested in gals. But when I was 17, building a Vamp Bat in a garage at 3511 Cook St. in Denver, I didn't have time for a date. I just wanted to get that plane up in the air."

You'd hardly suspect from his seat-of-the-pants verbiage that this is a guy who went to prep school and graduated from Yale, who took over the late Bill Lear's failing business and made the word Learjet colloquial enough to wind up in a Carly Simon hit tune. He comes on with the cocksure bravado of a test pilot: easier to imagine as a 4-year-old kid watching his father training in planes for World War I than sitting behind a corporate desk in home town Denver.

You can believe that Harry Combs holds the 11,678th airman's certificate ever issued in the good old U.S. of A., that he quit Pan Am back in the '30s because all they'd let him do was sell tickets, that he started a flying school and designed aircraft and still flied 30 hours a month. It's harder to picture him becoming -- 15 years ago -- the biggest Beechcraft distributor in the world. Too much forthright opinion to be a good salesman, you'd suspect. The kind of boneheaded conviction that made him take on the federal government.

"It all started," he says, "when Grumman wanted to apply for 47,000-foot certification for the Gulfstream Ii, and the goddamned Faa said it was unsafe for an airplane to go above 41,000 because of decompression problems. These guys weren't telling us anything we didn't already know. Jesus Christ, you can stick a guy's head in a pail of water and get the same results, I mean, if you're dead you're dead.

"So I said to the FAA: 'Look, I fly a Piper Cub at 500 feet and the wing comes off and I'm dead. How do you deal with that? You fix the wing so it doesn't come off. If you guys had anything to say about it, we never would have gone to the moon.'

"Jezuz. The feds. I've stayed away from selling to them. I don't want to be a government whore. We bent over backwards to prove to them that we could make a safe plane to fly at 51,000. We've got thest things built like battleships. You get them up to pressure, and fire .45s into the cockpit and saw away at it with band saws, and the pressure doesn't drop that much."

That's the way Harry Combs does things. Below the banter, he looks like a genteel businessman in a canary button-down oxford, a rep tie and herringbone jacket, with balding gray hair that's perfectly trimmed. He's got a ruddy, outdoorsy complexion, and he'll lapse into poetry he wrote in his youth. If you listened to the prairie wind It could tell you something . . .

He'll talk gently about elk roaming through the Rockies and sit in captivated silence as he removes his wrist-watch and notes the passage of the 59 seconds that the Wright's first flight lasted. And he'll say, with all the wonder of a kid sailing his first glider: "That's a long time when nobody in the history of the world has ever done it before."

And then the afterburners kick in, and here is Harry Combs the Honcho.

"The governor of Colorado is out at the ranch. The ranch? Oh, it's just a little one, 6,000 acres. Anyway, the phone rings and it's the FBI. And they're asking the government to find a good dude ranch where Neil Armstrong can hibernate after he comes out of quarantine from being on the moon.

'You put the first man on the moon on a dude ranch and there's gonna be thousands of people coming to look at him and not the horses. So I tell the governor that we'll just put him up at my place.

"Well, Armstrong calls me up and says: 'Harry Combs. I've heard of you -- the president of Gates Learjet.'

"And I say: 'Yeah. Well I've head of you, too.'"

About five years later, Armstrong gave Combs a small gift: a copy of the Wright brothers notebooks. And Armstrong told him that nobody had ever told the public how astounding their research really was.

"I look at this stuff," says Harry Combs, "and I'm amazed. I've been flying and selling planes for 50 years, and like most people I thought the Wrights were two weirdo bicycle mechanics who got lucky. I mean, this is a real eye-opener. This is a real piece of our national heritage. So I go out to Hollywood, looking into the possiblilty of putting a TV show together that'll get the story out. And this Hollywood producer says to me: "There's gotta be some sex.'

"Jezuz! So I decide I have to write, this book. I didn't get any advance, or any deal that it would be published. But I had to write it. I traveled all over the country. I'd dictate into a machine whenever I had time. Then I sent part of it to Marty Caidin, who really knows how to write about flying. I needed a structure for this damn thing, not to mention that when it was going out to publishers, they were gonna say: 'Who the hell is this Combs guy, some crazy plow jockey from the Southwest.'"

Houghton Mifflin published Harry Combs' "Kill Devil Hill" last week, with a shopping list of endorsements that includes test pilots, senators, novelists and astronauts.

"I wrote to everybody that I vaguely knew," says Combs. "I used to shoot rifles with Curtis LeMay. Jezuz he was good. So I wrote and said, 'LeMay, god damn you, you beat me so many times that you owe me one. Give me a blurb for my book.'"

Harry Combs got it: "a must for all Americans," Curt LeMay wrote.

"If I had known what a pain in the a-- it is to write a book, I never would have started," says Combs.

And then this, from the man who's sold a thousand Learjets:

"At least the planes sell themselves. You've really got to work to sell books."