Hello future Dirigible races and design competition contestants! I recently received a question from one of the groups who will making an entry into the RC Dirigible Races portion of the Symposium Games this year, and I thought I would give an answer publicly to benefit other groups who may be considering making an RC Dirigible themselves.
The Question was in regard to the concept of negative buoyancy in a dirigible, and the effect of a heavy powerplant on the rule that says:
“2. Type: All Dirigibles should be of helium filled/lighter than air type. No hot air dirigibles,
flammable gas dirigibles (no Hydrogen) or heavier than air vehicles (helicopters or airplanes)
allowed. This is to keep the field competitive speed and maneuverability wise, but also for
spectator and facility safety.”
The group in question is worried that their gondola and powerplant is too heavy to qualify for the specification “lighter than air” because it doesn’t float unassisted in mid air (the powerplant is powerful enough to lift the vessel even though the balloon can’t hold it up on it’s own). So in the interest of fostering some creative hobby engineering, I will make a clarification for rule 2 as quoted above.
All RC Dirigible entered in the races and design competition must have a helium filled envelope/balloon, that is at least capable of slowing it’s decent in the case of a power loss, or a cut throttle. Basically, if you have it flying near the ceiling, and your battery dies or your motors stop working, it shouldn’t fall straight to the floor. I would like to be able to give a specification on “fall time”. But at this point I will have to wait until my OWN Dirigible get’s closer to finished before I can make a spec for that. (Something along the lines of “fall time from 5 foot must be X seconds or more”)
So to sum up, don’t worry if your Dirigible design doesn’t allow for a free floating blimp, just so long as it doesn’t drop like a rock with a loss of power.
Also, I need to clarify that the use of toy grade RC airplanes, helicopters and quad copters as “powerplants’ in your dirigible is perfectly acceptable, as long as you didn’t just attach a balloon to one and call it done. If you are going to use an RC plane, helicopter or quadcopter as your powerplant, it must be integrated with a gondola of some kind.
Anyway, I hope to see plenty of RC Dirigibles this year, and remember to contact me as soon as you know what kind of remote control you’ll have and the frequency (if applicable). (See the RULES for more info)