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Old 09-30-2006, 06:46 PM
  #1
sharpshooter223
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Default zep

recently i have been longing for an rc zeppelin after watching a movie and several games. anyway, has anybody ever attempted this or know somebody who has.
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Old 09-30-2006, 09:42 PM
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Default RE: zep

I have seen helium dirigibles flown indoors. I don't feel this would be a good aircraft for outdoors though.
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Old 10-01-2006, 06:59 AM
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Default RE: zep

Do a google search for rc blimp or advertising blimp. There was a company making 30' rc blimps awhile back. Used Zenoah engines and had an autopilot with GPS. Flight time was up to 4 hours as I remember. They were using them for Advertising, program in a course and altitude, take off, it would fly the course and then return later. Pretty cool stuff, but expensive.........
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Old 10-01-2006, 07:36 PM
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Default RE: zep

yea, im not talking about a blimp, blimps suck, im talking about a zeppelin, there is quite a bit of difference there.
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Old 10-01-2006, 10:35 PM
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Default RE: zep

People,

This Sharpshooter is just trolling. Look for him and all his posts. The guy will waste your time.
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Old 10-01-2006, 10:45 PM
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Default RE: zep

Sharpshooter. Once again I call for you to use the Search tool we have here. There's past threads about this topic and a few projects if I recall. Years ago there was one written up in a magazine but I don't recall of one recently.

It's a LOT of very intense work to make all the frames and make them light enough and yet decently strong. The one that was in the magazine was 25 to 35 feet long with electric motors for the drive motors. It was also extremly fragile and could only be flown either indoors in a blimp hangar or outdoors on the calmest of days.
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Old 10-02-2006, 07:05 PM
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hmm, then my idea of a microflyer might be out of the picture, my main problem is getting a good source of hydrogen
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Old 10-02-2006, 11:17 PM
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Default RE: zep

A good source for H? Know anything about electrolysis? Do you know why you want H instead of He or is this another lame attempt to troll?
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Old 10-02-2006, 11:48 PM
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Default RE: zep

I did some research many years ago about making an R/C Hindenburg. I found that using helium the model would have had to be huge to even float at 1" of altitude. Hydrogen provided marginally more lift, but not enough to make a difference. Either way the model wouldn't fit in the house or go through any doors. It would be cool but we need something a lot lighter than helium if we're going to build small scale dirigibles.

And yeah, blimps suck.
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Old 10-03-2006, 12:57 AM
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Default RE: zep

Quote:
we need something a lot lighter than helium if we're going to build small scale dirigibles
Hot Helium?
Why not, it works for Balloons.
Electric coil warmer or exhaust gas plumbing/heatsinking... yes, a small one.... yes I know it wont work for Hydrogen.
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Old 10-03-2006, 09:21 PM
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Quote:
ORIGINAL: KidEpoxy

Quote:
we need something a lot lighter than helium if we're going to build small scale dirigibles
Hot Helium?
Why not, it works for Balloons.
Electric coil warmer or exhaust gas plumbing/heatsinking... yes, a small one.... yes I know it wont work for Hydrogen.
they dont use hot helium in balloons, if you are talking hot air balloons they dont even use helium they just stick some fire to any air that happens to be present. but hydrogen is the lightest you will be able to get. and for framework and stuff i was planning on making a carbon fibre frame covered with some sort of plastic film (i would be using the plastic from polybag for newspapers. and as for the air sac i was thinking of using some sort of thin latex or something of the sort. however, if it is built light enough, and has enough power behind it, it could probably fly without any floating gases. and by the way, if i ever build a good one, im not planning on makin it small. if i make a small one i will find some tiny rc parts from a nano flyer source. by the way dolanosa, i know about hydrolisis, however, with hydrolisis you cant easily get the hydrogen to compress, and then i would have to transfer the hydrogen to the air sacs, which is kinda hard without it being previously compressed. now, i got a fun idea from a few games, dont use any gas at all, build your airframe and everythign really really lightwieght, and then use 3 engines on each side with a front and pusher prop on every engine, and basically overpower the thing. or, if you are going for scale, biuld a very very lightweight zeppelin normally, and stick the engines in some fokker dr-1's built to the same scale as the zep, and stick those fokkers respectively off the side of the zep and use those for the power, and have the servos inside the zep for control.
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Old 10-03-2006, 10:29 PM
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Default RE: zep


I guess I missed a "...yes, I know hot air ballons dont use helium" in my post.

I was just refering to using something with no lift, air, and heating it to get positive boyancy, Hot Air. If Helium didnt have enough float, maybe Hot Helium would..... whatever you got, heat it for more "lightness".

I looked at making one once, and decided I would take the easy route and not make it a Lighter Than Air ship, but a Almost Light As Air ship- like a 5 or 6' derrigible at sub pound weight with servo tilt nacelles for VTOL/Stol & transition. Wind made me think twice about it.
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Old 10-04-2006, 01:17 AM
  #13
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Default RE: zep

Yeah, I'm afraid that a micro flyer Zepplin is sort of out of the question...

Hydrogen and helium have known lift values per cu foot. So you need to figure out how much equipment you need to lift and from that figure out how many cubic feet of gas you need. From there you get a first guess of the size of the craft and then you calculate roughly oversize how much structure you need and how heavy it will be and add the extra lifting gas volume to the picture. At that point the gas should all fit in the structure and you're good to start cutting out lots of skinny sticks of balsa to build the Zep from.

This is why those RC mylar blimps are the size they are. They need to be that large just to hold up the RC gear, motors and batteries plus the mylar itself.

Oddly enough air and hydrogen are still heavy compared to a true vacuum. If there was just some way to make a rigid shape that is as light, or close to as light, as the mylar bag you'd have a lot more lift if you take out all the air from the vessel. Air weighs about 1.25 kg/cubic meter at sea level pressure. Moist air weighs more at about 1.29 kg/cu meter. So if you could make a container of roughly one cubic yard and take ALL the air out of it you could use it to lift about 2 lbs. But making such a container that would withstand the pressure trying to implode and make it light enough to float it is well beyond our present material and structural abilities.
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Old 10-04-2006, 11:28 AM
  #14
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Default RE: zep

Quote:
ORIGINAL: BMatthews
But making such a container that would withstand the pressure trying to implode and make it light enough to float it is well beyond our present material and structural abilities.
Yes, you need to build it out of unobtanium.

Seriously, though, you could make a very light Zeppelin that's all space frame and very light covering, and then "cheat" by using clear Lexan for wings. Not quite the same, but workable. Kind of like the vertical fins on birdlike models. Can't see them from a distance. With a light-enough model, those wings wouldn't actually have to be particularly large, either.

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Old 10-04-2006, 12:16 PM
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Default RE: zep

Bruce-
Thanx for the numbers

So for a envelope of 2 cube meter, we can get somewhere between 0lb to 4lb boyancy (lift, "lightness") max. This is of course skewed to the 0-2lb range for stp gasses, or a wee bit more for low pressure envelope.

I'm looking at it as a matter of compromise: give a little on everything.

A vacuum would implode the craft, but what about just 1 or 2 psi of LowPressure to drop the ammount of mass in the gas. Or as I said, heat it some to drop the gasmass without Implosion. Play PVNrT to strike a ballance of Presure & Temp to get a lower Number of molecules

Hydrogen would work better than air (stupid 60%N), but while helium is not as good as hydrogen, its far better than air.

Lighter than air is really hard, but Almost as Light As Air is easier. Using Vectored thrust you can cheat the weight of the ship to get "Float" & "Rise" with less than a pound of thrust if a 3lb craft has 2lb of gas Positive Boyancy (lift,Lightness), thrust vectoring will eliminate the need for excessive winglets

I hope you can get the particulars worked out, would love to see a build thread on it
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Old 10-04-2006, 01:23 PM
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Default RE: zep

OK, let's assume a pure shere for the container as this is by far the strongest shape. A 1 cubic meter sphere will provide 1.2 kg of lift if it's a pure vacuum inside. 1/2 an atmosphere would give .6 kg of lift. 3/4 an atmosphere would provide 0.3 kg of lift and so on.

But even if you can draw out a measely 3 oz of vacuum that means you have to deal with 3 oz of pressure per sq inch on the sphere. That doesn't seem like much until you realize that this is 27 lbs of pressure on each sq foot of area. Even with only this measely 3 oz of pressure differential there's going to be literally hundred, if not thousands, of pounds of pressure trying to crush that sphere into a flake.

I used to see this pressure and weight deal in scuba diving. The aluminium tanks were actually slightly boyant when empty but about 3 to 4 lbs negative when full. That's 80 cu feet of air causing this change.
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Old 10-04-2006, 01:48 PM
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Default RE: zep

True, with PSI its not the P's that get you, it is the SI's

Sure just an ounce or two could get crazy amounts of "crush" going on on a big ship. It would have to be spherical, or at least mostly cylindrical to use circles to stand upto the compressive forces, and even then it wont take much to implode it.

But imagine as you get a few milibars of vacuum, and see the sides start to suck in, you hit the Heater Element to bump up the temp, thereby bumping up the pressure to "ease the squeeze". Over a period, and in balance, you suck 1/4 atm vaccum, and heat the gas to a 33% expansion... you have 75% the weight without the crush. Of course, I'm just throwing out a swag as to the temps involved to get a 33% expansion from 80degree nice day air- could be it would melt the envelope.

anybody have the interest to crunch the PVNrT numbers for temp change to get from N to 3/4N? or from 1atm to 1.33atm if that floats you boat.

oh, You dont happen to have the weight/density of Helium at 1atm?
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Old 10-04-2006, 05:42 PM
  #18
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Default RE: zep

i have already drawn my plans for a zep on the computer so i think i will make a small model and see if i can make motors that will lift it by themselves
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Old 10-05-2006, 12:25 AM
  #19
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Default RE: zep

Sharpshooter-
the good news is:
We all know motors and engines these days do have enough thrust to hover a craft with no boyancy, so in that perspective, you can be guaranteed to get a hoverable Zep no matter how much effect you get from the gas.

Nowhere to go but up
post lots of pics of the construction
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Old 10-05-2006, 03:05 AM
  #20
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Default RE: zep

But KidE' If you balance the pressure by heating the air to keep the sphere from becoming overloaded then you may as well just use a slack bag envelope and put preheated air into it right off the bat. A classic hot air balloon.....
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Old 10-05-2006, 05:50 PM
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Default RE: zep

my first model will be a flying model but it wont acctually be rc, it will only be about 15 inches, i think i will try to make it out of carbon fibre if i dont have to spend too much, otherwise it will be balsa/music wire. if you would like to see pictures of the progress, then i will create another post sometime, so keep watching for that.
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