If you ask devoted Boeing (BA -0.37%) shareholders why they own it, they'll tell you there are about 787 good reasons to buy Boeing stock today -- and maybe more. Yesterday, Boeing announced that it's landed 102 orders for its most advanced Dreamliner airplane yet, the 787-10, with United Airlines (UAL -2.83%) signing up to buy 20 of the new birds, and Air Lease (AL 0.31%) and Singapore Airlines tying in the race to buy the most -- 30 Dreamliner-10s apiece.

And yes, the plane is incredibly popular. Boeing has already booked in excess of 840 orders for Dreamliners of various shapes and sizes. At the company's planned year-end, 10-planes-per-month production rate, that works out to a backlog of orders stretching seven years long. But did you know that the 787 Dreamliner isn't the only Boeing product that's doing well?

The best offense is a great defense business
Over on the other end of its business model, Boeing stock has a secret weapon that's getting far less attention than the vaunted Dreamliner -- and far less attention that it deserves.

Source: Wikimedia Commons.

That business is the business of building helicopters -- the CH-47F Chinook heavy-lift helicopter in particular. Over the past week, Boeing has received two blockbuster orders for its big bird. First the U.S. Army granted Boeing a contract to buy 177 Chinooks over the next several years, at a total cost of $4 billion. The Army says it may up that buy by a further 38 helos, potentially pushing the contract value past $4.8 billion.

But that's not all. Within days of receiving the Army contract, Boeing landed a second multibillion-dollar contract -- this time to build an unspecified number of Chinooks for the militaries of Turkey and the United Arab Emirates. Boeing's base contract here is quoted at $3.4 billion in value. If "optioned" helos are ordered on top of the base number, however, the value could rise to just under $5 billion.

Result: close to $10 billion in new revenues for Boeing.

To put that number in context, that's about 60% of the revenues coming into Boeing's Military Aircraft division annually. But as important as these revenues are to Boeing stock, the quality of these revenues may be more so. Boeing's Military Aircraft division may not be as profitable as United Technologies' (RTX -1.07%) Sikorsky unit (at 10.5% operating profit margins), or Textron's (TXT -1.04%) Bell Helicopter (15%), but with a 9.6% operating margin, it's still the second most profitable manufacturing unit Boeing has.

Long story short, these are big revenues, and high-margin revenues, that Boeing has coming down the runway. The more Chinooks Boeing can sell, the better it will be for Boeing stock.