Sunday, January 29th, 2012 10:41 am GMT -6 Sunday, January 29th, 2012 10:41 am GMT -6Sunday, January 29th, 2012 10:41 am GMT -6

I’m consulting for a company that is building an UAV (unmanned aerial vehicle) designed to fly in the stratosphere.




Less Expensive Satellites

Satellite Costs

The average cost of a Space Shuttle flight, including all indirect expenses, was about $1.5 billion dollars. The cost of sending one pound (0.5 kg) into low earth orbit varies depending on which launch vehicle is used, but typically runs about $10,000 dollars. It can cost $100,000 per pound just to design, build and test a satellite that can survive for years without maintenance in the vacuum of space.

Needless to say, sending a satellite into orbit is extremely expensive. But does it really need to be that way? Most satellites are used for communications. What if we just flew an airplane really high and put all the communications gear on it? To be useful it would need to fly for a long time, so we are probably talking about a robotic pilot.

Say hello to Mr. HALE.


High-altitude long-endurance (HALE) is the moniker given to UAVs designed to fly this mission. Let’s look into more detail at the two requirements: high altitude and long endurance.

High Altitude

For safety’s sake, it would need to fly above commercial airliners. These don’t fly above 40,000 feet (12,000 meters). The very top of the worst thunderstorms can reach really high, up to 65,000 feet (20,000 meters), but these are relatively rare. They normally don’t go any higher than the airliners.

Long Endurance

Ideally a HALE UAV should stay up as long as the satellites they are designed to replace. In other words, years. Nobody has come even close to achieving that. Despite several attempts over the years, the current world record for an unmanned HALE flight is two weeks. It goes without saying that the company I’m consulting for is determined to shatter that record.

Finding Professional Help

Model Airplane Design in Practice

Most model airplane designers use the TLAR (that looks about right) approach. They study successful model airplane designs and closely follow proven formulas about what works and what doesn’t. Overall, this is not a bad approach. It saves lots of time and works really well as long as the new design is similar aerodynamically to what came before it. If you want to design and build a scale model of a unique subject, following this formula is strongly recommended.

This strategy falls apart when nothing that has flown before is similar to what you need to build or when the goal is to design something that flies better than what came before it.

For example, in my ModiFly design, I forced myself to work from a clean sheet of paper. I wanted to create an innovative design, which meant I had to ignore the proven design recipes and forge ahead down the road less traveled. I wanted ModiFly to be a breakthrough design, which meant lots of hard work. In the model airplane design world, what I did is relatively rare.

UAV Challenges

UAVs are being flown in all sorts of missions that were previously impossible. Their design requirements are different from those of model airplanes and different from those of full-size airplanes. Because most UAVs are small, similar in size to model airplanes, full-size professional airplane designers are ill-equipped to tackle the challenges. As I explained above, most model airplane designers are also ill-equipped to handle the challenges.

Why They Call Me

There’s not too many folks around that have written books about model airplane design that cover the more technical topics in a way that is easy to understand and apply. If you want to build an UAV and don’t know where to start, you are likely to do an Internet search. It’s not uncommon for them to find my website and then contact me.

Future Articles

In future parts of this series, I plan to write about the technical challenges of a HALE project and what airplanes that meet those challenges look like. I will also talk about the different ways that the risks in such a project can be minimized and kept under control. This is a fascinating project, and I’m really looking forward to writing about it. Stay tuned!

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