Building things that fly is hard. The constraints on small, battery powered, radio-operated gear already presents a challenge, but adding weight, balance, and aerodynamic constraints takes it to a whole new level. Sophi Kravitz rises to the occasion and discusses each challenge of building a blimp from start to finish in her presentation at the 2018 Hackaday Belgrade conference.
One of the pleasures of writing for Hackaday comes through the incredible array of talent and experience to be found among our colleagues. We all do our own work, but one is humbled by that which flows from the benches of those one works alongside. Just such a project is the Remote Control Mini Blimp from our colleague Sophi Kravitz. It’s a game involving an obstacle course and a set of remote-controlled blimps. The challenges in such an endeavour have been pushing the limits of what is possible with off-the-shelf components. Continue reading “Hackaday Belgrade: Sophi Kravitz’s Blimp Army”→
At my university, we were all forced to take a class called Engineering 101. Weirdly, we could take it at any point in our careers at the school. So I put it off for more interesting classes until I was forced to take it in one of my final years. It was a mess of a class and never quite seemed to build up to a theme or a message. However, every third class or so they’d dredge up a veritable fossil from their ranks of graduates. These greybeards would sit at the front of the class and tell us about incredible things. It was worth the other two days of nondescript rambling by whichever engineering professor drew the short straw for one of their TAs.
One greybeard in particular had a long career in America’s unending string of, “Build cool stuff to help us make bad guys more deader,” projects. He worked on stealth boats, airplanes with wings that flex, and all sorts of incredibly cool stuff. I forgot about the details of those, but the one that stuck with me was the Cyclocrane. It had a ton of issues, and as the final verdict from a DARPA higher-up with a military rank was that it, “looked dumb as shit” (or so the greybeard informed us).
The Cyclocrane was a hybrid airship. Part aerodynamic and part aerostatic, or more simply put, a big balloon with an airplane glued on. Airships are great because they have a constant static lift, in nearly all cases this is buoyancy from a gas that is lighter than air. The ship doesn’t “weigh” anything, so the only energy that needs to be expended is the energy needed to move it through the air to wherever it needs to go. Airplanes are also great, but need to spend fuel to lift themselves off the ground as well as point in the right direction. Helicopters are cool because they make so much noise that the earth can’t stand to be near them, providing lift. Now, there’s a huge list of pros and cons for each and there’s certainly a reason we use airplanes and not dirigibles for most tasks. The Cyclocrane was designed to fit an interesting use case somewhere in the middle.
In the logging industry they often use helicopters to lift machinery in and out of remote areas. However, lifting two tons with a helicopter is not the most efficient way to go about it. Airplanes are way more efficient but there’s an obvious problem with that. They only reach their peak efficiency at the speed and direction for which their various aerodynamic surfaces have been tuned. Also worth noting that they’re fairly bad at hovering. It’s really hard to lift a basket of chainsaws out of the woods safely when the vehicle doing it is moving at 120mph.
The cyclocrane wanted all the efficiency of a dirigible with the maneuverability of a helicopter. It wanted to be able to use the effective lifting design of an airplane wing too. It wanted to have and eat three cakes. It nearly did.
A Spinning Balloon with Wings
Four wings stick out of a rotating balloon. The balloon provides half of the aerostatic lift needed to hold the plane and the cargo up in the air. The weight is tied to the static ends of the balloon and hang via cables below the construction. The clever part is the four equidistant wings sticking out at right angles from the center of the ship. At the tip of each wing is a construction made up of a propellor and a second wing. Using this array of aerofoils and engines it was possible for the cyclocrane to spin its core at 13 revolutions per minute. This produced an airspeed of 60 mph for the wings. Which resulted in a ton of lift when the wings were angled back and forth in a cyclical pattern. All the while, the ship remaining perfectly stationary.
Now the ship had lots of problems. It was too heavy. It needed bigger engines. It was slow. It looked goofy. It didn’t like strong winds. The biggest problem was a lack of funding. It’s possible that the cyclocrane could have changed a few industries if its designers had been able to keep testing it. In the end it had a mere seven hours of flying time logged with its only commercial contract before the money was gone.
However! There may be some opportunity for hackers here. If you want to make the quadcopter nerds feel a slight sting of jealousy, a cyclocrane is the project for you. A heavy lift robot that’s potentially more efficient than a balloon with fans on it is pretty neat. T2here’s a bit of reverse engineering to be done before a true performance statement can be made. If nothing else. It’s just a cool piece of aerospace history that reminds us of the comforting fact that we haven’t even come close to inventing it all yet.
If you’d like to learn more there’s a ton of information and pictures on one of the engineer’s website. Naturally wikipedia has a bit to say. There’s also decent documentary on youtube, viewable below.
We wonder if a floating wind turbine generator (translated) like this one would alleviate some of the complaints we hear about ground-based turbines. This huge helium-filled structure is designed to generate electricity at high altitude, where winds are stronger and blow much more consistently than near ground level. We’ve read complaints at the unsightliness of wind farms, and the noise that they make as the turbines spin. A test run took place at only 350 feet, but this generator is meant to fly at an altitude of 2000 feet. We’d bet it’s much less obtrusive and much quieter at that distance.
There isn’t a whole lot to the lighter-than-air assembly. It’s got an aerodynamic balloon with stabilizing fins, and a propeller attached to a generator at the center. The tether that holds it in place also carries the conductors which translate the power down to the ground. There is mention of a fail-safe system that allows for a slow descent if it get gets away from its tether, so you shouldn’t have to worry about the sky falling on you.
It’s certainly an interesting idea. For some reason this makes us think of the space-based solar generator panels found on Larry Niven’s Ringworld.