Carlos T. Miralles is a senior program manager at AeroVironment, Inc. where he is responsible for new business and concept development.

In 1981, he completed his BS in Aeronautical Engineering at California Polytechnic University at San Luis Obispo. With his twenty years of experience in aerospace, Miralles is currently working on the aerodynamic and conceptual development of unmanned air vehicles (UAV) and related technologies for terrestrial and planetary applications. He also developed and managed the "Vector" vertical take-off and landing UAV design and flight demonstration, which included the first known successful transition from hover to forward flight and back to hover for a vehicle of its class. Miralles was also involved in several other innovative ground and air vehicle concepts and technologies, including a Mars Airplane design, and was a major contributor to several NASA mission proposals.

Miralles also teaches a summer-term course in Automotive Aerodynamics for the school of Industrial Design at the Art Center College of Design, Pasadena, CA. A licensed private pilot, Miralles took First Place in the 2000 Region 12 Sports Class glider competition.

4.27.01 Luis Esparza asked:
Why is it that insects seem to fly much more efficiently than the machines scientists have been able to build? Insects can fly really fast (too fast to run away from when they chase you), really far like bees looking for honey, and can hover and stop almost at will. Is it possible for us duplicate this level of performance now or in the near future?

Mirales' response:
Luis,
Good observations. It will be quite some time before we can emulate the flight of insects, but I think we will eventually get there. Insects first started flying about 300 million years ago. Man has only been flying on the wing for the last 100 years. With larger flying machines, man has been able to fly to far greater heights, carry more weight and fly faster than nature has ever been capable of -- but that was the easy part. We're still learning.

On small scales, the size of small birds and insects, man made flying machines have not even come close to achieving the performance and agility of nature's flying creatures. Serious research into the kinematics of flapping flight has only been accomplished in the last six years or so. We are currently limited by our technology.

One important limitation is the power and energy density of batteries, which fall far short of what's required to mimic insect flight. For instance, a dragonfly requires about 0.02 Watts for level flight. To fly for just 10 minutes the battery alone would weight about 1 gram. A complete dragonfly typically weighs only 1 gram, and that includes a flight control system, collision avoidance system, an energy replenishment system, a reproduction system, and more!

Another problem facing scientists and engineers is the complexity of flapping flight. Although we now have a good understanding of the kinematics involved, the materials, sensors, mechanisms and actuators required to replicate flapping flight on a small scale do not yet exist.

For more technical information on flapping flight:
The Biokinetics of Flying and Swimming, A. Azuma, 1992

4.27.01 Frank Yeske asked:
Carlos, do you think that these "eyes in the sky" model planes will be available to the public in the future? I have always been interested in combining photography and flying. I'll be looking for your BLACK WIDOW in the stores. I'm a 48-year-old steel worker with the heart of a 10-year-old. Thanks for listening.

4.27.01 Perry Thornton asked:
My two girls were watching Scientific American Frontiers last night and they got very excited about the Black Widow and the other plane with a video camera. If we wanted to build a plane like this, how would we get started?

4.27.01 Igor Pimenov asked:
Hi my name is Igor Pimenov and I'm 14-years-old. I have been in the R/C Planes hobby for over 3 years. I have a huge interest in small aircraft that have a wingspan of 20 inches or less. I'm very interested in your Black Widow. Could you tell me more about the type of servos and batteries you used? Could you tell about the type of camera you used and where you got it?

Mirales' response:
Frank, Perry and Igor,

It is very unlikely that an airplane like the Black Widow will be in stores any time soon. The six-inch span constraint forced us to develop highly specialized electronics and sensors to achieve the desired performance. The commercially available parts were just too heavy and inefficient. Even the servos are highly specialized and cost $2000 each.

The good news is that there is a growing movement in the model aircraft community that is developing very low cost, easy to fly, light weight and small electric airplanes -- and you can buy them today. You can even buy a camera and downlink transmitter for the video. These models are typically much larger and don't perform as well as the Black Widow, but they are much more practical for recreation and great for both kids and adults captivated by the idea of flight.

Here are a few web links for more information:

• RC Microflight Newsletter
• Homefly.com
• Todd's Models
• Sky Hooks & Rigging
• Grand Wing Servo
• Marshall Electronics
• Supercircuits
  
  Have Fun

4.27.01 Hector Sburlati asked:
Mr. Miralles,
I have designed and built a small scale of an airplane. The model is a delta design with 2 turbo-props pushers mounted on top at the rear of the plane. I would like to make a flying model but I need to know the c.g. before I can start building. Is there a formula that I can use to figure it out? I'll appreciate it.

Thanks.

Mirales' response:
Hector,
There are some general rules-of-thumb which can help approximate the center-of-gravity (c.g.) location for a flying wing. But you have to be careful, especially with airfoil selection, twist distribution and thrust line placement. These factors can greatly effect the c.g. location and flying qualities of a flying wing. Without more knowledge of your design, I can only recommend some reading that should be helpful to you. Tailles Aircraft in Theory and Practice, by Karl Nickel and Michael Wohlfarht, AIAA Educational Series, is a great place to start. Also, look for reference material on the Northrop and Horten flying wings at your local library.

You can also take a "cut-and-try" approach to estimating c.g. position by building very simple and low cost glider models to experiment with c.g. position and trim. Start with a simple thin-sheet balsa wood or egg-crate-foam sheet model with a 12 to 16 inch span, and don't worry about the airfoil shape for now, just make it a flat plate. Using clay or pennies taped to the nose, balance it at a point just forward of the mid-point between the nose and trailing edge. This works as a good starting point for a simple low aspect ratio delta wing planform but not a higher aspect ratio wing. Then trim the glider by bending the trailing edge up small amounts until it flies properly. And don't forget to put a vertical tail on the rear. You will have to make adjustments to the c.g. and trim depending on the specifics of your design.

This should get you close enough to work on your larger flying model and give you some practical understanding of the longitudinal stability of your design. But be prepared for big changes depending on your choice of airfoil, body shaping, thrust lines and other details of your design.

Good Luck!

4.27.01 Wayne asked:
It was very interesting watching the Pointer launched by one man, and then, kind of float/glide down to earth, after you had cut the engine, for a (usually), soft landing. But, even though you have cleverly designed easily damaged parts as replaceable, why risk a hard landing at all? It seemed that once you cut the engine, it was pretty easy to determine where the plane would come down. Why not get two people to stretch out a net, and catch it in between them? No hard crashes; no replaced parts. The plane can't be that heavy if an ordinary joe can throw it into the air. Maybe a soft net, held horizontal, 20' wide, or a circular net on a soft flexible tubing, something like camping tent flexible, joined poles, maybe 15'-20' in diameter.

Mirales' response:

Wayne,
Clearly you have made some good observations and pondered the problem we have wrestled with for some time. As it turns out, we've explored the possibility of landing our unmanned aircraft a number of ways, including the use of nets.

The Pointer weighs about 9 pounds and has a 9-foot wing span. Using the deep stall auto-land, an expert pilot can usually land it within 20 feet of a pre-selected point in daylight. A foot soldier with minimal training (about one day) is usually lucky to get it within 100 feet, and with some practice can usually land within 50 feet. Moreover, it is usually flown at night making it hard to do precision landings. It would have to be a very large net. The Pointer is actually designed so that some of the parts come off in a landing and can be snapped back together in a few seconds. Usually, none of the parts actually break.

Also, because Pointer is designed to be quickly and covertly launched and retrieved by troops, we had to keep the number of parts and steps in the process to a minimum. Having to carry the parts for a net means leaving something else behind or having to carry more weight. Having to set-up and take-down a large net means being exposed longer and limits the users' mobility.

4.27.01 Robyn Allen asked:
I am a high school student in central California who is very interested in going to Mars someday. I watched the Scientific American Frontiers show in which you spoke about your invention (the folding plane) and I am wondering if you can give us information about how you got involved with the space program. I am really interested in what types of classes you took at school and essentially what your stepping stones were to get to where you are now. Also, I would love any information about exactly what your title is and what kind of people work in your department. Thank you very much. P.S. I fly gliders too!

Mirales' response:

Robyn,
It's good to hear from young people that wish to someday realize the dream of traveling to another planet. I truly hope you succeed and that I will see you walking on Mars via my television (or whatever it is we're watching then).

If you have a desire to learn more about the space programs and particularly what is going on for Mars Exploration, see the web sites:

• Jet Propulsion Laboratory
• The Planetary Society
• NASA Headquarters

Most of my involvement in the space program is through the Mars Airplane activity. How I became involved is far too long a story to tell in full here. But I'll try to answer some of your questions.

I am an aeronautical engineer by training, with a degree from California Polytechnic University in San Luis Obispo, 1981 (before you were born!). My course work included studies in aerodynamics, propulsion, structures, physics, calculus and many other subjects. Most of the classes were required, and I took some post graduate technical classes for electives.

Just as important as the academic studies was my passion for anything that flies, beginning when I was very young making model airplanes and continuing through hang gliders and sailplanes during high school, university and beyond. I still fly as often as I can. Often, I would look for any opportunity to help on projects like a human powered aircraft, or take a summer job at an airport, even offer to wash an airplane in hopes of getting a ride. The value of learning through practical experience motivated by passion for a subject cannot be underestimated.

My career started while in school designing, testing and marketing hang gliders for two manufacturers in California. After graduation, I worked for several years at Northrop on the B-2 and a number of other exciting projects. Then, after a couple of years at North American Aircraft, I was offered a job at AeroVironment (AV) where I am now a Senior Program Manager and do a lot of new business development. I've been at AV for over 11 years. I still get to do a lot of fun technical work.

AV first became involved in space technology through a relationship with the Jet Propulsion Lab (JPL) and involvement in the early Mars Airplane concept studies of the late 1970's. Later on, AV consulted for the energy storage and propulsion systems on the Pathfinder Sojourner rover. In the last few years, I had been working on projects involving small, unmanned aircraft that folded into containers and could be deployed from other aircraft or launched out of tubes. I was also working on the problem of flight at 100,000 feet here on earth (an environment similar to the Mars atmosphere). When JPL needed a consultant to develop a small airplane that could be folded into an entry probe for Mars, we seemed to be a logical choice.

I am very fortunate to be working with a lot of talented and dedicated individuals. Most (about 80%) of our division is comprised of degreed engineers. We also have several extremely talented craftsmen that turn concept designs into reality. What AV has been able to accomplish would not have been possible without the contributions of everyone working on each of those projects. Although education is important when we look to hire someone, great value is placed on personal experience, demonstrated accomplishments, desire to learn and ability to be a contributing team member. Most schools unfortunately do not offer many opportunities, either in class or in extracurricular activities, to gain experience working with other individuals as a team toward a common goal. It is a valuable experience. Seize it when the opportunity presents itself.

4.27.01 William Hughes asked:
I saw the Sky powered glider with Alan Alda on PBS. Is it possible to get one of these to do research on population counts of Sea lions and birds here on the Oregon Coast? Thank you, Bill Hughes

4.27.01 Bill Chambers asked:
Carlos,
I am a vegetable farmer interested in sustainable agriculture and I think that a possible application for your "spy plane" would be for crop scouting fields for pests, especially if the camera can be equipped for recording in the near infrared. Can you tell me how to get more information on purchasing or renting of one of these planes?
Thanks for your help.

Mirales' response:

Bill and Bill,
Your suggested applications are very insightful. A number of government projects have or are investigating similar things using unmanned air vehicles (UAV). This includes surveying crops to see what portions of coffee orchards are ready for harvest, detailed mineralogical surveys, and other applications. Although I have not personally heard of anyone wanting to use UAVs to conduct aerial surveys of wildlife, it would not surprise me if someone has -- it sounds like a good idea. Practical UAVs for these kinds of applications are on the horizon, but not yet available to the field researcher, farmer or entrepreneur wanting to make a business of this. The problem is primarily the high cost of these systems, not so much the technology.

The individual markets for non-military applications are very small and do not, in and of themselves, justify the kind of investment required to develop the products and services needed. Most likely, the military will have to make a large procurement in order for the economies of scale to reduce the cost of UAV systems to a level that is acceptable. Then, it will be up to small, specialized companies to take the production UAV and adapt it for a specific commercial or science application.

Small and inexpensive video cameras are already available, however the near infrared cameras and other specialized payloads needed for many applications are still much too large and costly. Then we need to develop the computer codes and displays that make it possible for a farmer or field researcher to interpret the data and use the information to take action. These too do not yet exist. More government investment is still needed.