As you can see, my airship design has reached a much more advanced stage. I will be constructing a balsa/lightweight plastic 20' flight test test model in my 2 car garage over the winter. Once the airframe passes some tests not conducted in a computer generated wind tunnel then hopefully it will be on to building an even bigger one. This finished Colossus will measure 160' in overall length and 72' wide for the airframe and she'll stand 118' from the strut to the main rudder.
Powered by 12 electric 6 blade vectored thrust props which will be able to steer the craft in something like the airship version of three rectangular arducopters bolted to each other. Not only will the housings pivot to allow more stable ascent/descent, the props also pivot out within the housing to allow lateral thrust capibilities.She'll be very maneuverable, and computer testing indicates the airframe will capable of some new maneuvers previously unknown to rigid and semi-rigid airframes such as lateral crabbing, and pivoting in a full 360 ciricle on her center-point within her own shiplength while making a vertical ascent or descent. This is a design change which can enable much safer landings and take-offs in windy conditions and perhaps prevent the pilot error which led to the hindenburg diaster from ever happening again.
The connection pylons between the main hull and the flight nacelles are airfoils which have air current forced over them by the forward engines. This adds to the lift and stability of the craft allowing it to reach higher speeds than have previously been attained by similar craft, and is one of the design features which should enable it to perform some fairly impressive maneuvers once in the air.
The main hull is semi-rigid with a pressurized envelope, similar to the Zeppelin-NT, however with a different internal framing configuration (obviously such would be necessary) and the flight nacelles have a lightweight rigid configuration with semi-pressurized helium cells.
She will be able to be operated fully autonomously, remotely operated by a single pilot wile the drones operate autonomously, or the gondola can easily be reconfigured to allow a single pilot to physically control the vessel if desired. The gondola also houses the auxilliary electric generator to allow for operation in a cloudy environment or if the solar electric system fails for whatever reason.
The battery banks providing power to each of the engine-pairs are located amidships and each nacelle is independently powered and recharged. The odd pattern of the solar cells are based on the weight of the lightweight flexible amorphous panels I could find information on. That pattern represents the best weight distribution to be able to achieve independent powering.
The drone launch and recovery system, mechanically, will be very similar to the original system designed for the USS Macon, Akron, and Los Angeles. However the drones will have cradle supports which lower fore and aft (not detailed in these photos, nor is the drone fuselage configuration to enable launch/recovery)
She's carrying 8 scaled down lightweight electric versions of the MQ-1 which are recharged by the on-board solar system. The drone wingspan is 18 feet. It is capable of carry drones with up to a 24' wingspan and gross weight of 350 lbs per plane. and obviously the system could be reconfigured to accomodate smaller craft. The way it works is really cool. The craft are stored so close together that instead of having a lowering design for launch, I worked it in to the craft are stored at different distances from the hull. The fore and aft drones are stowed 7" lower than the amidships drones.
The drone launch process will have to occur in a paired sequence for balance purposes, and the thrust configuration greatly stabilizes the craft and makes her a lot easier to balance, so the stowage level only makes it easier to conduct the launch sequence and it keeps the drones closest to the most balanced point. Once all the drones are away, the launch/recovery hooks raise up into the rigid hull of the flight nacelle and are kept close to the hull to increase aerodynamics. When it is time to recover the craft, the L/R trapeze descends to its full length to allow recovery of in-flight craft after others have already bee recovered.
The on-board sensor package is pretty modular actually. You can do a lot with this airship configuration. I have hard mounted fore and aft gimbals on the main hull and amdships gimbals on each flight nacelle. The bay in the main hull is also a sensor bay and acess panel. Fuel stowage for the auxilliary generator is in wing tankage in the two airfoils and the ship will carry approximately 4-8 hours worth of fuel currently, but more fuel storage can be added.
Unfortunately the laws of physics concerning rigid and semi-rigid airships dictate that the 20' model will be able to lift it's own airframe and that's about it. I should be able to include a single mini-cam on a gimbal but that's really it. She won't be able to carry a functional payload until she's at least 80' in overall length and even then we're talking some pretty small (under 100 lb each) planes.
I'll post more photos and stuff as they are generated and more news on this project and how it's going. Till then. Happy Flying!
Comments
The rigid frame of the flight nacelle is a faraday cage in and of itself. That's always been one of the upshots of rigid airship design. The recovery equipment is coated with nonconductive materials. It could be struck by lightning several times without affecting flight handling characteristics or damaging on-board equipment. This is one of the primary reasons I went with a hybrid rigid design.
Don't forget, the US Navy actually did this with real pilots flying Curtiss FC-9 Biplanes on 4 different airships from 1924 to 1936. The airships, and airship carrier program as a system wasn't a failure, it was airframe design flaws for the airship itself coupled with bad piloting that brought down the American airship carrier program launching and recovering the planes ended up being the easiest part to carry off.
There is almost no force being applied to the recovery trapeze while the aircraft is hooking on. The difference between speeds is negligible. Remember, the airship and the drone both will be travelling at speed of approximately 30-40mph as the drone is hooking on. Not the same type of landing environment as a naval aircraft carrier so it doesn't need the braking equipment needed to land a jet on the Nimitz.
I would imagine a more slack tethering system would hold more promise.
If those drone-holds are rigid, then the structure must absorbs in an instant, the full force of the delta-v * m.
Perhaps a slack-line tether, similar to an inflight fuel line...
But again, the rigid frame would need to be checked and tightened at least once every 7 days to ensure frame strength. But coming down to the ground for about 6 hours every 7 days doesn't really make much of a difference considering the area that can be covered the rest of the time it's up there...
I would actually recommend lowering the craft down to either a ship at sea for an unrep (underway replenishment). It could also be accomplished at any airport with helium blimp facilities. So, the airship itself would not actually have to be married to a single geographic location for it's operability. It would be easier for an automated system to drop a hose that a person plugs into a replenishment tank than it would to make a fully automated airtight replenishment connection while in-flight. However, I think in-flight helium replenishment would be able to be accomplished if the airship had a pilot aboard as they could plug a hose dropped from a replenishment plane into the necessary intake nozzles mounted in the control gondola. Sort of a helium probe and drogue as it were.
I suppose for extended flights there could be mid-air refill of helium?
The helium is retained in the exact same it always has been with semi-rigid and rigid designs. The semi-rigid main hull is itself "the gas bag" and is presurrized to an enormous level (think of a balloon as hard as a 2 by 4 plank of wood) with a much smaller, ligher weight rigid frame on the interior (rather than the series of rings in a classic rigid Zeppelin-type design) which adds stability to the overall airframe and allows for things to be hard-point mounted to the sides of the envelope (the gas bag).
The rigid flight nacelles have a series of cells inside them which are inflated to a lower level than the semi-rigid. Basically a bunch of REALLY big helium balloons They are hung from the top of the frame when deflated.
They will leech gas over time, everything does. Also helium is sometimes vented during flight, but my design doesn't require as much helium venting to maintain balance as a single hull design does. There will be enough helium tankage aboard to compensate for what venting and other loss may occur, and the ship will retain enough helium to maintain useful positive buouyancy for about a week until it will have to come back down for a refill. Operationally it will probably be on the ground more often than that as rigid airframes also need to be tightened from time to time as well as there is quite a bit of rigging on the interior which helps ensure the stability of the airframe.
It can probably safely stay in the sky for 3 days at a time, unmanned, with a big enough window of resources left over so that you're not stretching it but could remain aloft for an entire week if need be. This could come in useful when sending the airship overseas from a central operational location. If the airship is manned, the flight duration will be much shorter simply because of the pilot themself.
Need to up the weight allowance for the pilot. 190lbs for the human, sure, but 30lbs each for coffee and another 10lbs each for snacks ;)
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