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The "S.A.S. ELEANOR PAGE", or Biography of a Crash Project
Created by John Campbell on 10/2/2013 4:45:20 AM

The "S.A.S. ELEANOR PAGE", or Biography of a Crash Project. Airship build and leassons learned


It all started with a clown fish....   

For the first Steampunk Empire Symposium Airship Race, I obtained a pair of Air Swimmers Clown Fish (I thought the orange of the plastic parts would go better with copper and brass paints) and proceeded to paint the gasbag; unfortunately, I underestimated the weight added by the paint and the fish couldn’t swim anymore, so we took the other stock one and entered it.  My nephew Naaman Taylor piloted it, while I walked before it, feeling out the winds for him so he could compensate, and we finished our heat before anyone else.  But, we didn’t win; strictly speaking, we weren’t flying an airship.     

After the first Symposium, I was determined to make a purpose-built dirigible.  I worked for several weeks on it. (I plan to finish it for the Third Symposium, though it may violate part of the rules. We'll see.) When I realized about a week before the Second Symposium that I wouldn't be able to finish in time, and, of course, I panicked. I looked over what I had access to, and what I could get locally (no time for Amazon), and what I could do with it.     

I had already obtained a supply of balloon foil from BalloonKits [1] for making a gasbag; I calculated out the largest prolate spheroid (think lemon instead of pumpkin), the best compromise between a sphere and a teardrop I could think of, that I could make that would fit within the 72 inch maximum dimension limit and the 38 inch width of the foil [2].  This calculated out as giving about 7 ounces of net lift (11 ounces of total lift, minus 4 ounces for the envelope).  I thought brute force would be a better way to go than finesse, given the time constraint, and a lot of lift would allow me to use standard hobby-grade R/C components, without having to spend more for the really lightweight ones.  Besides, the only scale I had access to could only measure 0.1 ounce/5 gram increments, and the bigger the dirigible was, the less fine accuracy mattered.  I made the template and ironed and cut the gasbag.     

It leaked like a sieve.  So I made another, increasing the heat setting and using waxed paper as a lubricant, as recommended in the BalloonKits instructions.  It leaked a little, but I sealed the gaps in the seam and went on.     

Once I had the gasbag, I decided to make a rudder for steering, as I had a lightweight servo and foam sheet.  That was straightforward, so I won’t go further into it, except to say I left protruding tabs to allow it to be taped to the gasbag.

 

This picture is of the rudder being repaired in dry dock; when
she was being transported from DragonCon, the crew did not
secure the helium tank properly, and it rolled over the fin and
broke it.  Nothing that couldn’t be fixed, and in fact it already
has been.


Click image above for closer view.

To change altitude, I took the rack and pinion
gondola and track fromthe previous year's
Air Swimmer clown fish, nipped off the extraneous
plastic, and soldered the electronics package
from a servo to the gearbox motor so it could
be controlled by a standard R/C receiver to move
the C/G fore and aft to raise and lower the nose
(which is how the clown fish had changed altitude)
[3] [4].  Because the plastic partswere orange,
and I couldn’t paint them without possibly gumming
up the rack and pinion, I painted the fins orange to match.

Click image above for closer view.

 

 

 

 

I went to HobbyTown USA to get a driver. I had decided to use a ducted fan, because I planned to mount the driver on the gondola, and there would be a dangly control cable to the rudder servo, and propellers might get tangled in it. I bought the smallest ducted fan unit they had and an ESC (Electronic Speed Controller) suitable for the fan motor, and a pair of batteries that had the capacity to run the fan at full output for at least 5 minutes (ALWAYS have a spare battery).  I took them home, epoxied the fan to the gondola gearbox, and soldered the wiring as necessary.  I then velcroed the ESC, R/C receiver and battery to the outside of the fan duct, along with a lightweight wheel.

 

    

I made a pair of fixed horizontal fins for stability, taped the track, rudder “canoe” (well, that’s what it looked like) and fins to the gasbag with packing tape, and was done. At about 8 PM of the Thursday evening before we left at 4 Friday morning for the Symposium.... But she worked. Ballasted for low negative buoyancy, she won her first heat handily.  This is how she looked, sitting on Bosun Taylor’s head (the Bosun is in charge of the small craft…):

We came in second overall.  Unlike the previous Symposium, there had been limited time to practice, and I did not find out (nor did Naaman) that she didn’t turn to starboard as quickly as she turned to port until well into the final race, and he got stuck on the walls and corners.      The  version that we entered at DragonCon had only minor changes, the most important being an ESC with a reverse, and fixing the problem with the uneven rudder tab movement.  With the larger rudder tab, she can turn 180 degrees in twice her length now at low speed, in either direction.

LESSONS LEARNED (Mostly from the Symposium Races):

Brute force remains a valid way to solve engineering problems.

Finish in time to let the pilot get in some practice.  This seems obvious, but is harder than it looks.  This will also allow you to find and squish any bugs.  One hopes. Always carry more repair/replacement parts and supplies than you expect to need, especially batteries.  Besides, being sporting people, someone else may benefit, and if they can’t run, you can’t race.

Try to have a reverse capability; backing the dirigible away from a corner you’ve gotten yourself into is much faster than running to the corner and pulling her out by hand.

Your engineering solutions may override your artistic ones; due to the use of a ducted fan on a moveable gondola with the electronics velcroed to it (the simplest way to arrange things), there was little I could do to SteamPunk the dirigible, especially as I was coming perilously close to HTA flight as it was.  Of course, the converse may also apply.

NOTES:

  1. http://www.balloonkits.com/ sells the balloon foil and tools for working it, and has excellent instructions.
  2. I used the Web site http://www.cleavebooks.co.uk/scol/callipse.htm for calculating the parameters for the ellipse template, and of the ellipsoidal gasbag skin at http://planetcalc.com/149/
  3. http://todbot.com/blog/2009/04/11/tiny-servos-as-continuous-rotation-gearmotors/ is a good description of how to modify a servo for continuous movement; you can also use servo control electronics as a reversible ESC for brushed motors that are the same capacity as the one in the servo.  The article at the link discusses using soldered-in resistors to replace the potentiometer; I left it in the circuit so I could adjust the motor output without having to adjust the transmitter.  If someone wants to use the same device for C/G changing, Amazon sells the electronic parts of Air Swimmers for less than the whole fish.
  4. If you look closely at http://www.youtube.com/watch?feature=relmfu&v=V8l27w3iBHo&app=desktop, you can see the “Eleanor Page” make a dip at the beginning; this was because the Bosun had the gondola all the way forward, and she was nose-heavy.  You can see her nose come up as she starts to move again, as he moves the gondola aft.  The wheel mounted on the underside of the fan duct helped keep her from snagging on the carpet.

Final Note:  The “Eleanor Page”, both airship and group, were named for a young woman of whom I was more than fond, dead these 27 years.  LTJG Eleanor Page Hull, USN (deceased).  Sailor, rest your oar.

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