On Tuesday this week I had the opportunity to attend my fifth NASA Social. This time I was back at the NASA Armstrong Flight Research Center at Edwards Air Force Base, about ninety minutes north of Los Angeles in the Antelope Valley.
The main focus of this NASA Social was the LEAPTech project. LEAPTech stands for “Leading Edge Asynchronous Propeller Technology.” We’ll get to what that means.
When we were out here for the “FlyNASA” event in November, there were some delays in getting us all on base in our individual cars. This time we met off base and were brought in on an Air Force bus, which made it a piece of cake.
These events start early. We were at the sign to be picked up at 0700, which for me meant being out of bed at 0345 and picking up other Social attendees at 0600 (many folks coming in from out of town didn’t have cars). There aren’t many things I’ll happily get up that early for – a NASA Social is one of them.
This is where they store the nation’s strategic reserve of flat, hard, and empty.
Edwards Air Force Base is centered around the Rogers Dry Lake, an ancient lake that long ago dried up and left a really big, really hard, and really flat surface. That’s perfect if you want to test aircraft that might be having any sort of emergency and need to land whenever and wherever they can. No need for any conventional paved runways, although they do have four of them. All of the other runways (over a dozen) are simply lines laid out on the lake bad.
That’s perfect if you have an experimental aircraft (or spacecraft) that might need more room to land than a conventional paved runway has, or might not be able to hit the runway exactly on the mark. You’re a little bit sideways? No worries. You need to land long and then roll for a few miles? No worries. This is why the first Space Shuttle “drop tests” or “free flight tests” were done here, the first two Shuttle flights landed here, with a total of 54 Shuttle landings at Edwards.
Once at the Armstrong Flight Research Center, we got checked in and made official. (Yeah, there’s a typo in my name, but they’re not the first and won’t be the last.)
The public information office at Armstrong is lead by Kevin Rohrer (at left), and this NASA Social was the first one run by Anna Kelley (at right). We got introduced to each other, got settled in, and got started.
Dennis Hines, Director of Programs at NASA Armstrong, welcomed us and started to introduce us to LEAPTech.
NASA Armstrong has six primary research goals. All of them are important for our air traffic control system and next generation aircraft designs, but some are more “flashy” than others. For example, item #2 there, “Innovation in Commercial Supersonic Aircraft,” is finding ways to reduce sonic booms to the point where commercial aircraft can fly over land without bothering people at the surface. This will allow future aircraft to fly supersonic anywhere, not just over the oceans like the British/French Concorde did.
The LEAPTech program falls under both the “Ultra-Efficient Commercial Vehicles” and “Transition to Low-Carbon Propulsion” areas. Put as simply as possible, LEAPTech is trying to replace today’s two or four huge jet engines slung under the aircraft wing with an array of much smaller engines placed along the leading edge of the wing.
This has a lot of potential benefits. It will let the wing be smaller but with better handling and maneuverability, particularly at low speeds. It will be more efficient, by a factor of five or more. It will use electricity from batteries (much like today’s electric cars) instead of fossil fuels. Best of all, it will be much, much more quiet than today’s jet engines.
The efficiency gains come from the more efficient nature of electric power versus jet engines. Today’s best jet engines are only about 23% efficient in turning energy (fuel) into thrust, where electrical motors are more than 97% efficient. When you add in the gains from having a smaller and more efficient wing, you can get up to a factor of five improvement.
Testing the LEAPTech concept is the first hurdle to clear. This is a small program, working fast and cheap. A more conventional program might test its designs in a wind tunnel. But wind tunnel facilities are expensive and access is limited. It could take two years just to get on the schedule, and the testing there would be bigger than the entire budget for the program.
Instead they’re taking an idea used by Scaled Composites in Mojave when they were designing some of the Virgin Galactic vehicles. Instead of going to a very controlled, rigid, and expensive test environment in a wind tunnel, they simply built their hardware, put it onto the top of a truck, and ran it along the runway. By taking data in the real world, being quick and flexible in making changes and repeating the tests, they were able to move ahead much more quickly on their project.
LEAPTech took the Scaled Composites idea and upgraded it to benefit from some of the lessons that Scaled learned. Out of that came HEIST, the “Hybrid-Electric Integrated Systems Testbed.” It puts the LEAPTech wing and engines higher off the ground and out of ground effect (a phenomenon that affects an aircraft’s lift when very near the ground). They also found ways to stabilize the test rig, isolating it from the truck body so that vibrations and bumps from the running vehicle won’t affect the data being collected.
Starr Ginn and Mark Moore (the project’s Principal Investigator) gave us the big picture of how LEAPTech will work and why it’s such a big deal. For example, you know those winglets on the tips of almost every commercial jet these days? Those were developed by NASA Armstrong and save about 3% in fuel for the airlines. That might not seem like much, but for someone like United or American Airlines, 3% savings on fuel can be billions of dollars over a couple of years. So what if some of this technology can save 10% in the 2020’s?
The other big deal is the noise reduction. A typical propeller has 300 or so horsepower going into three or four blades. That’s about 100 horsepower per blade, a lot of which is turned into noise, and the blades are all putting out noise at the same frequency, multiplying the effect. That’s why propeller planes can be so loud. (As someone who loves the sound of our P-51, Bearcat, or Spitfire roaring to life at the CAF, I don’t see what the problem is, but maybe it’s not about me.)
Now replace that one or two props with eighteen much smaller ones, each with five blades. Each engine has only forty or fifty horsepower, spread out over five blades, so each blade makes much less noise to begin with. Instead of a roar, the sound is more like a loud cloud of buzzing bees. That’s when the “Asynchronous” part of LEAPTech comes in. With the electric motors, you can have each propeller spinning at a slightly different frequency without losing thrust. By doing that, you spread the noise out even more. The final sound ends up sounding a lot like the old Jetsons’ car.
Having met a whole slew of project engineers and scientists and seen dozens of slides and charts, it was time to see the real deal. We got back on the bus and headed out toward the lake bed. While we were stopped to wait for clearance and to check the bus tires for FOD (Foreign Object Debris), Mark Moore answered questions. He’s a really passionate guy about this project!
Finally, just before we got out on the lake, we got our first view of HEIST and the LEAPTech rig on top of it. It was time to follow them out and see some actual engineering and science being done.
Tomorrow, the lake bed and the test run.