A challenge to all: lighter than air airfiles; please comment

[Guest CX001]

Hey everyoneAlong with the 307, i've been flipping back and forth between modeling ZRS-5, the USS Macon, the US Navy's last rigid Airship. I've been mentally trying to work out a way in which one could somehow come close to a LTA aircraft using airfiles desinged for fixed winged aircraft. I've thought of thrust vectoring, but i'd like to leave that option in reserve. This sounds like some gauges to control lift plus a highly tweaked airfile. I'd love to hear any ideas you guys can come up with to get close to a powered blimp/airships's flying qualitites. I am aware of Bill Lyon's Hot Air ballon airfile, which would make a great place to start, probably. I haven't taken a look at it, but i'd guess the wing area is very large. Hot air balloning doesn't require gas vents nor does it require ballast for the most part, however, and an airship is powered, which adds another whole dimension. The USS Akron and Macon could rotate the propellers to direct thrust in about a 220* arc, if i'm not mistaken. I'd love to be able to somehow be able to direct thrust so that I could simualte vertical takeoffs they would do with the Akron and Macon. For those who aren't familair with rigid airship flying, here's how it worked on advanced airships of the 1930s. For those who are, ship to the bottom unless you feel like checking this. ;-)1. The Airship is filled with enough lifting gas to carry the empty weight and a good payload(I have all the specs for the Akron and Macon lying around). Cold weather causes the lifting gas to become more dense, therefore either more gas is needed or payloads need to be reduced. An option if it's sunny is to let the airship "bake" in the sun to warm the gas. I don't know about Hydrogen filled airships, but this method was used often enough on the US Navy's blimps and airships. 2.To keep the airship on the ground yet have enough lift to lift off on it own, the airship is ballasted with water. Usually, the water is in tanks fore and aft of the center of gravity, so it can be used for trimming where you need to move fast. 3. To keep the gas cells from bursting, and for descent if neccessary, the gas cells are fitted with release valves at the top. Most were manual and automatic, meaning that overpressure would open them, and they could be opened manually if the situation required. 4. In all rigid airships, and almost all blimps from about WWI, the elevators are controlled with a wheel whose axis is parallel to the elevator's axis. A trim gauge (similar to a rudder gauge on ships) is used to indicate the angle of the ship. More later on this for flying. The rudders are controlled by another wheel, but this one faces forward, like on a ship. A compass is very close by usually, as are gas and water ballast controls and a telemotor(like on a ship) to signal to the engines what power is required. 5. Most rigids had fixed engines and prop shafts, and all except the USS Akron and Macon had the engines mounted in external pods. 6. Flying gets complex. You must remember that while the gas is meant to lift the ship, the hull also generates lift. In heavy flying, the airship can be trimmed to produce dynamic lift, to augment the static lift, produced by the gas. For takeoff, airships are walked out of the hagner, or undoked from a mast, and then pushed up, or let go, at which time the commander would order engines to propel the ship forward, or in the Akron/Macon's case, the props could be vectored to produce upward lift, or ever reversed to popel it backwards or down. Differential thrust was also possible. Once away from the ground, the elevator man would hold a climb rate given to him by the commanding officer, and the rudder man would hold a heading. Of course, winds like to blow such a large machine around, so dealing with drift and head/cross/tailwinds can be difficult at times. Heating of the lifting gas and burning of fuel, oil, and coolant influence the ship's lift to weight ratio. The Akron and Macon had water reconvery devices which recovered most of the water from the engine exhaust. When it came for descent, most of the time, it could be made by just pointing down at the ground. If the airship has been heated, this can be difficult unless you release gas, which can get back at you when you are on finals if you release too much. Helium was so precious in the '30s that often if this sitatuion arose, the ship would wait until nightfall for the gas to cool and then they would land. Enough babling, but to the unitiated, there's a crash course in rigid airships. Sorry for the very long post. :-( Thanks guys, and be creative!P.S. Here's the state of the USS Macon curently. The main hull was diffcult at times since the girders merge near the aft fuelage(changing the number of sides from 36 to 24, to 8) and I had to get creative to keep a smooth outline yet a sharp edged cross section on the envelope. I think it turned out great. Tons more to go, though. When I get tired of this I go back to work on the B-307, andback again when I get tired of the 307. :-lolhttp://forums.avsim.com/user_files/25094.jpg

[Guest CX001]

Come on, guys, there have to be a few of you out there with some ideas. :-)

[Guest Fabio Miguez]

Hey Chris,Amazing looking ship, bro! I love the modeling.Regarding the AIR file, I think you may have better luck if you go here http://www.avhistory.org/scripts/MegaBBS/f...w.asp?forumid=5 This is the forum where all the major league AIR file gurus hang out at. They might be able to help you.

[Guest CX001]

Many tahnks, Fabio. I'll try that place. This place is more sided to gauges and some modeling. :D