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Dec 21, 2006, 05:22 AM
Registered User
A few details on my R-100, since I was asked. I built this model 13 years ago (with some upgrading 5 years ago) so it uses components now long since superseded. One could do much better now.

Size is 1/120 scale, which means it is 1.77 metres long and 90 litres volume. Total weight is 90 g, about 50 g airframe and 40 g systems (propulsion, control).

Propulsion is by one 3.7 gram very expensive Swiss DC motor in the rear gondola (a pager motor would now be as good, and much cheaper). Radio is a home-built 3.5 g Rx, with 3 channels (rudder, elevator, motor). Speed controller home-built based on ZN409 chip. Servos were stripped down Union 14 g servos (long since obsolete), using only the motor, amplifier and feedback pot; the gear train was replaced with a pulley and cable system; final servo weight about 5 g each (still heavier than current Falcon servos). Power for all from 5 cells 120 mAh NiMH.

Hull was built from balsa strip longitudinals and rings, 4 of the rings having a truss structure (like the actual R-101 rings). Covering was 6 micron polyester film (mylar). It has one internal gas bag, also of 6 micron mylar (and thus no internal transverse bracing of the rings). I made the hull in 2 halves (top and bottom), mounted on a building board (standard model plane fuselage procedure), covering each before removing from the board, then put the gas bag in and joined the 2 halves.

The gondolas were fibreglas mouldings (single ply 17 gsm glass). Control car balsa and paper. Scale details account for about 10 g of weight. The hull is very accurate to scale, based on a drawing I got from Shuttleworth in UK. Details include handrails, exhaust manifolds, nose mooring, external bracing wires. Only the one functioning propeller deviates, being considerably larger than scale (but you don't see it when its spinning!).

Of course its for indoor flying only. Top speed is about 4 knots (2 m/s). It responds well to elevator, but turning radius is rather large (it can't quite do a figure 8 in a basketball court). Battery gives about 10 minutes running.

I hope that satisfies curiosity.
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Jan 02, 2007, 02:21 PM
Registered User
That's cool Alan, a video of the airship motoring about a local indoor gym would be great to augment your reply, ^^ I'd never thought to make the airship in halves then put them together to create the hull.

Great work, and hope to see more lta from you if you continue to build them.
Jan 02, 2007, 04:42 PM
Mostly harmless
My friend, knowing my skills with wooden/composite aeroplane structures, made an unofficial offer for me: He wants me to build him a
6-meter rigid RC airship for outdoor use. Now I'm asking is he totally out of his mind or what? A blimp would be better if you ask me, but he insists on it being a rigid... I quess he wants it to have some historical look, but he haven't yet disclosed what historical rigid he wan'ts me to build. I quess he doesn't know that either.

I have my suspicions towards the project. One could get around 7 cubic meters gas volume with 6 meters, but if it has to be very slim, I quess only 4 cubic meter volume would be achievable if it still has to look like a zeppelin... I quess it would have hard time lifting itself. and if there are issues with the lift, so will there be with power.

So what do you think? Should this project be buried before it even starts or should I give it a try? I quess I would make the hull in three pieces to make the transportation easier. (helium is very expensive here, thus it makes sense to transport the pieces with inflated gasbags)
Last edited by Kernwrech; Jan 03, 2007 at 05:07 PM.
Jan 06, 2007, 04:55 PM
Mostly harmless
hmm... If one builds rigid airship, one could make the gasbags out of very thin metallised mylar, instead of heavy PU or vinyl. And even more importantly, the bags doesn't have to be pressurised to maintain shape, thus better gas retention would be achieved...

any ideas?
Apr 17, 2007, 05:46 AM
Dark Lord of the Sith

Rigid LTA


I am looking at doing something similar...in the form of Rigid LTA RC.

Not Zep though, rigid shell, maybe 2m long, .75 m high, .8m wide , lifting body, twin vertical tails (all moving rudder), horizontal stabilizor (fixed), canards (all moving as elevators ..or is that elenards?)

brushless motors pylon mounted mid section, possibly vectoring up and down....

mmmm...what else, helium bags made from airship ballonet material (since I work for a company that makes 'em, I hope i can get some) , thinking of 3 bags above midsection, then 4 below, maybe 5 to surround the electronics...

so far calculations indicate I would have about 4 kg (8.8lbs lift off airship grade helium)

could just work.....maybe

www.aeroscraft.com
Apr 18, 2007, 12:15 AM
Mostly harmless
Perhaps not so many bags of different size. That'll make inflating a mess and even more importantly, the weight will probably turn out to be too much.
I would suggest building only two or three bags that will be filling the entire hull (minus RC gear).

BTW, what's the point with rigid if you don't build it as a scale model?
4 kg of lift? Now how did you calculate that? I quess your airship would be more like a sphere than a blimp with 2 meters lenght.

I considered some kind of hybrid (a semirigid) in my project, but I quess that project is frozen until I can build more gastight envelope (the present one is good, but not good enough). I have a rigid keel made of balsa, mainly to distribute the loads better, but also provide some rigidness if the envelope pressure is lost (due to a pinhole or something)
Apr 18, 2007, 01:17 AM
Dark Lord of the Sith
It will be scale model, of a hybrid aircraft my company is developing. Check the website.

Thought about the bags too. Wanted more for redundancy if get damaged, but you are right, one bag for top, one bag for below. Still thinking how to do the connection for inflation.

Tray in between with electronic gear will house the servos, 4, rx , esc, batt etc.

Canards (or canavators in front), horizontal stabs and fins in back , maybe foam, maybe balsa and cover with mono or ultracote or somthin'

Dimensions are preliminary, might be bigger. Dont have the drawings and calculations of how I got to that figure with me, there in USA, I am in China right now. But basic volume calculations and medical grade helium lifting/bouyancy calculations.

Also restricted by size of SUV !
Apr 20, 2007, 12:14 PM
Dark Lord of the Sith
does anybody have info on working with carbon fibre specifically on an LTA project like this ?

Or could you please just point me in the right direction ?

thanks a lot !
Apr 21, 2007, 10:13 AM
Mostly harmless
Actually... this link was posted here some years ago:
Behind this link you'll find amazing piece of carbon fibre workmantship. It turned out to be heavy however...
Apr 21, 2007, 10:24 AM
Dark Lord of the Sith
Thanks, I'll check it out.

Actually just sitting and working on my design now, up to 9 pages of ideas and options on installing servos, clambshell design, electronics, etc.

I have been worrying about the weight...but then I remember its not an LTA model ! Ha, its a Hybrid ! So the Helium will help a little, as it should and the rest of the lift will be from the aeroshell....anyway, put a big enough motor on a brick and it'll fly too.

The mold was stumping me, but I think I have it 90 % figured out.....will try to make one aeroshell out of carbon fibre and then use that same shell to measure for balsa ribs and spacers. Then will construct the sister ship. One will be vectoring thrust props and I'm thinking about putting EDF's (x3) on the second one.

Maybe the EDF's on the carbon ship, they will be mounted in the tail, so now have a problem in getting enough airflow to them, as I do not want to duct intakes through the model. Maybe a louvre system above and below the EDF intakes.

I have no clue about the total weight yet, so will start looking in more detail at motors etc at a later date, but I guess they will be pretty powerfull, so the vectoring can pull the model up. I'm thinking to ballast it slightly tail heavy, so the nose will rise first if the props are vectored 45 or 90 degrees up.
Last edited by Skaz; Apr 21, 2007 at 10:38 AM. Reason: I cnat spelle!
Apr 21, 2007, 10:28 AM
Dark Lord of the Sith
Wow, that is some fine workmanship....
Apr 21, 2007, 07:07 PM
dusty bible = dirty life
Majortomski's Avatar
Skaz, my dad was a Sr design engineer for Goodyear on the blimps. When I built the 13 footer in my avatar I had hoped that it had enough surface area to develop dynamic lift just like the 1:1 ships do. Even at 13 feet and 130 cuft it is still too small to even see any dynamic lift. I think if you fly your aeroshell with and without helium, at the scale you're proposing, you're going to see very little mesurable difference in performance.

Ever read a book by the name of "The Deltoid Pumpkinseed"?

Folks were attempting to do what you are trying way back in the 70's

t
Apr 21, 2007, 09:03 PM
Dark Lord of the Sith
Majortomski, yeah, I know about the Pumpkinseed. I also know they failed. Im my opinion, hybrid aircraft, with todays technology (I'm talking full scale aircraft not models) are completely feasable.

I am under no misconception with this model; I dont expect it to fly like an F16 ! Chances are one of the two (the EDF model) wont even get off the ground, the one with vectoring might...maybe.

It is an intellectual and practical undertaking for me. If it works, great, if it doesnt, well, I would have had fun building the blasted thing anyway!
Apr 30, 2007, 07:17 PM
Registered User
Another rigid model I recently found out about:
http://www.starksravings.com/shenandoah/shen_model.htm
Oct 20, 2017, 12:34 PM
Registered User

Wow


I can't tell ya how much it warms my heart to see this page. I have been working on this project for going on 15 years now. This will be my 3rd attempt at making a working model. The final will be 55 feet long when completed. My largest problem is where to store it. The largest ring is (You see here) is 72 inches in diameter.


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