An RC model of the Confederate Sub-marine Boat H.L. Hunley: Scratchbuilt H.L. Hunley from plans I made from National Park Service in-situ (on site) sketches of the actual hulk of the sub. See those sketches and photos of the actual boat and download a PDF of their findings and measurements at http://www.cr.nps.gov/history/hisnps/submerged.htm
Note - now that the real sub's hull has been excavated, there are several inaccuracies revealed in the drawing below - including the fact that the real sub has a violin shape to her bow! (See drawing at bottom of this page).
See NEW drawing at bottom of page at 9/1/2000
February 18, 2000: I have the foam hull halves completed and covered it with five coats of latex house paint, a method pioneered by Jeff Jones. The paint should protect the foam from deforming from the "exothermic" heat created when the epoxy and fiberglass cloth is applied to create the shell of the hull. (I have since found out that this was an unnecessary step, since catalyzed epoxy resin doesn't generate as much heat as the polyester fiberglass resin that Jeff used.) After the shell is done, it will be cut in two and the foam will be removed from each half by mostly mechanical means (the claw end of a hammer) and the last little bit melted out with acetone.
Foam blocks of left and right hull halves are glued together.
2/23/00 I have now "laid up" three layers of 6 oz fiberglass cloth with West System epoxy on the two foam hull "plugs" and am now in the week-long curing stage. After putting on the three layers of I hung two heat lamps over the hull halves to make sure they stayed at about 95 degrees F for 24 hours to hasten the curing process. The rest of the week-long cure process, the hull halves are housed in a box with a 100 watt light bulb to provide the necessary heat. (According to epoxy expert Matt Thor I should wait at least one week before putting on the final layers of glass cloth.)
After foam hull halves are painted, the first "lay-up" of glass/resin is done on a tee-shaped board that allows the cloth to hang straight down as it hardens. This makes trimming much easier after all the layers have cured.
3/9/00 I am in the "cure" stage of the final lay-up of fiberglass. The second lay-up, done ten days after the first, was two layers of 4 oz. and one of two oz. fiberglass cloth. I have also finished the ring that represents the one the Confederate ship builders put around the propeller to prevent tangling by harbor flotsam or fouling ropes tossed by Union sailors. To make the ring, I wrapped a 2.5" cardboard mailing tube with wax paper and then wrapped layers of fiberglass cloth with epoxy resin between layers. I had to do this a second time because I felt the first ring I made was too thick to be scale.
3/26/00 I cut the hull into top and bottom halves with my Dremel tool and a reinforced cutoff wheel and then removed the foam hull form. It took a bit of digging with a screwdriver and clawing with the claw end of a hammer, but I got most of it out. I dissolved the last few bits by pouring in about two ounces of acetone solvent. I was still left with some pretty stubborn paint stuck to the inside of the hull so it took a sanding drum in my electric drill to remove most of it, then a smaller sanding drum in the Dremel tool. Then finally, a Brillo pad and lots of elbow grease to get the last few spots.
I reattached the bow and stern top sections and reinforced the area where I joined the left and right sides with a fiberglass tape Band-Aid. I then placed another layer of epoxy saturated six ounce cloth inside the hull to strengthen everything.
4/14: I sanded off the outside fiberglass strips off that I used to temporarily attach the left and right sides together and added an "indexing lip" all around inside the hull for the top cover to rest on.
4/28: Since this method of fiberglassing doesn't lend itself well to sharp angles, I am now working the bow and stern with automotive filler putty to try to achieve the "sharpened chisel" look of the real boat's bow and stern.
NOTE: Since I am trying to simulate rough iron boiler plate using polyester auto filler putty (Bondo) troweled onto the hull, a smooth surface would be a detriment so I will have to rough it up with 80 grit sandpaper before applying the the Bondo. A nice "tooth" or bumpy surface is necessary on epoxy to get Bondo to adhere properly. After the Bondo is applied and shaped using dams of layered masking tape to create the edges of the "plates", then the "rivets" will be simulated by attaching lead bird shot from shotgun shells sunk half way into holes drilled into the hull.
After the rivets are placed in small holes drilled into the hull and CA cemented in place, I'll then wrap the whole hull in 3/4 ounce fiberglass to keep everything from falling off if the model gets bumped.
May 8 - I'm building the water tight cylinder! I am making a combination of the WTC made by Jim Butt shown on this website and the one done by Matt Spade that is in the June, 2000 SubCommittee Report (issues #40-41) with several of my own variations including a very low RPM gearmotor I found at www.jameco.com. Since the prop is so large, I wanted to keep the maximum RPMs down to 200 or so.
MAY 12 - Work begins on raising the REAL Hunley, sunk some 4 miles off Charleston, SC. Go to the Charleston Post and Courier's webpage devoted to updates on the project - http://www.charleston.net/pub/index/hunley_index.shtml
Photo by Andy Hunt May 13, 2000 - Here I am at the SubRon6 May Fun Run in Champaign, IL with the H.L Hunley as she stands right now. The red glop on the bow and stern is "Red Cap" auto body filler. I am holding the bow "manhole" or conning tower in my right hand.
MAY 30, 2000 - Hot News! New information has been coming from the Hunley recovery project site off Charleston. It includes the revelation that the torpedo spar was not a 22 foot wooden one mounted on the top of the bow as was commonly thought, but instead, a 17 foot iron rod that protrudes from the center of the bow, much like a swordfish beak. Also revealed in a press conference last week was that the bow has a rake on the bottom so it juts forward farther than the top edge of the bow. Wow! For more information, check the Charleston Post and Courier's coverage on the Hunley recovery at http://www.charleston.net/pub/index/hunley_index.shtml
June 2 -Soldering prop blades to hub. The "T"-shaped upholstery pins are used to hold the blades into the slots cut in the hub. I "interpolated" the prop blade conformation by looking at and tracing photos of the props of several Confederate gun boats that have been salvaged and are now on display at a museum in the South. Since the real sub's recovery, the photos of the H.L. Hunley's prop seem to indicate I am pretty close to the way it really looks.
The "twist" was calculated by using the "charting" method explained by David Merriman in issue #43 of the SubCommittee Report. Also go to Kurt Greiner's website that does a super job of explaining how to make your own prop including some neat tricks to keeping the blades all the same size. I don't own a lathe so I had to ask Paul Hruby who has a more understanding "chief purchasing officer" to spin one for me. I was able to cut the slots by using my Micro-Mart cuttoff machine.
New 6/7/00 Trying the prop on for size. Also shown are the prop shroud ring and shroud mounting brackets. The brackets are probably a little too coarse to be perfectly scale but when the real boat is recovered, I will be able to see how the ring was really hung on the hull and maybe get a little closer. The graph is the chart I did to determine the "twist" of the propeller blades.
6/11/00 MORE HUNLEY SURPRISES - As divers dig deeper they discover that the torpedo spar is not mounted in the center of the bow, but more towards the bottom similar to the model built for the 1999 TNT Network "The Hunley".
6/21/00 - SHIFT IN STRATEGY - Several modelers - Steve Reichmuth included - have recommended that rather than trying to build up the hull plating using Bondo exclusively - I should use lightweight styrene plastic wrapped around the fiberglass hull and just fill in gaps with the Bondo. Makes sense - so that is my next step on the hull as soon as I get definitive hull conformation info from the Hunley recovery project. Right now, I am still working on the WTC.
9/1/00 New sketch of H.L. Hunley showing curved bow, spar torpedo mounting yoke, wrap-around dive planes and dive plane guard fin. (1/23/01) I think my dive planes aren't quite right. From more closely inspecting the precious few photos that are available, I believe that the inside edge of the planes wrap around the hull, but the outside edges are pretty much flat and parallel to the main body of the hull. Copyright 2000 Tim Smalley
1/16" brass plate was cut to shape of the Hunley's "true" bow curve and inset into a slot cut in bow. Holes were drilled in the brass to allow "Fixit" material to bond to the metal.
Building up my bow with "Fixit" to achieve the curved shape evidenced by the real sub. I didn't want to hacksaw off the bow and try to make a new one. Paul Hruby suggested that I cut a piece of brass to match the tracing I made of the photo of the sub in the Charleston paper and set it into the bow of my model with epoxy. I then built up Apoxy "Fixit" (www.aves-studio.com) to the shape of the hull. It smoothes easily using your finger and a little water. When it dries, I'll sand it smooth. The mooring / tow line hole was just drilled through and the appropriate diameter aluminum tubing was cemented into the hole and sanded flush. Photo is cover picture from the Charleston, SC Post & Courier the day after the Hunley was brought to the surface.
Dec 18 -I am now applying styrene plastic to my scratch-built GRP hull to simulate the Hunley's hull plating. I use Weldwood Non-flammable Contact Cement to bond the styrene plating to the fiberglass. This stuff has the advantage of non-toxic vapors, it doesn't melt styrene, and cleans up pretty well with H2O until it has set. It is then impervious to water. Cyanoacrylate (CA) glues are not recommended for use for long exposure to water (Mike Dory disagrees) and epoxy doesn't seem to bond with the styrene very well.
I am using measurements I took from Chapman's 1864 painting to estimate the plating size, since the concretion coating on the prototype Hunley has so far confounded researchers' efforts to determine the plate size. They have found that the plates are half plates rather than quarter plates as originally thought and there about 50 rivets per half circle.
Home-brew ballast tank built according to Matt Spade's instructions published in the SubCommittee Report (March 2000). I have since switched over to the Dr. Art Broder RCABS ballast system. See
Amidships view showing the styrene plating.
Sorry about the poor quality image. It looks like the hull is bowed in the middle but it's not. I used my camcorder to take these views so the resolution isn't as high as I would have liked. Burglars have since helped themselves to my old camcorder, so I hope the new one I get will take shaper "still" photos. I am now in the process of building up the plating using "Easy Sand" auto body filler from Evercoat. Sub-Committee webmaster Andy Hunt gave me this stuff and it is far easier to work with than Bondo, or Evercoat's other body filler products. I'll post some more views as soon as my new camera arrives!
March 6, 2001 - With the almost daily revelations about the Hunley as she is being excavated, I am pretty exasperated at this point with the whole damn project. Since they have discovered that the plates are butted together rather than overlapped, I have had to add a ton of "Evercoat Easy Sand" auto body filler to create that effect on my model. To create the gap between the plates, I have been burying a piece of fishing line under the filler and then pulling it out after it has set for a couple of minutes. It cuts a nice sharp line (as long as the filler hasn't set up too much - it needs to be about the consistency of cake frosting.) If the fishing line isn't in the correct position, the line is VERY crooked! I will post a couple of photos soon.
March 26, 2001 I finally got the expansion strakes glued on (.033 styrene sheet glued on with 3M two-part adhesive) and a coat of primer applied. The snorkel box is not seated yet - I have to cut a slot for the actuator to stick down through the top of the hull to attach to the pushrod from the servo.
December 15, 2001. I have been messing around with the single rod rudder control as employed by the Hunley. The above sketch done by Chapman in early December 1883 hints at a swinging control and a rudder slider bar. Several members on the Yahoo Hunley chat board (http://clubs.yahoo.com/clubs/csshlhunley) have discussed this thoroughly and I think this is correct. I have made a brass model on a board just to test the theory in metal.
Although there is a lot of torque necessary to turn the rudder hard over, I think that this is the mechanism (below) I will go with. I hope a standard servo will have the muscle I need! (01/14 - after lubing up the linkage and working it a few dozen times it has loosened up quite a bit. The servo cranks the rudder over about 30 degrees.)
Greg Sharpe - of Deep Sea Design and Development suggested the above arrangement (circled) for the servo rod through-hull. While more delicate than I'd like, it seems to work fine.
Testbed trial from the side.
From the back.
CU of slider bar and ball joint.
Installed on model
Showing linkage to WTC rudder output
Close up of linkage
My HL Hunley with her top off ~ The open space between the dive planes is where the ballast tank will be installed. I have since built Lexan tank saddles and brass straps to hold the tank in place in the sub.
Trimming in the tub. I placed a piece of lead on the top to see where it needs to be along the centerline of the inside keel.
May 2002 Her first run. Almost as successful as the prototype's trial runs (in other words - not very!)
Back to the drawing board to reconfigure the motor/ESC/prop to give better run time. Even with 4:1 gearing, the heavy pitch on the prop only allowed for a few minutes run time. David Merriman III had a similar problem when he scratch built his Hunley several years ago and had to go to a 9:1 gear ratio. I still need to apply rivets along the hull expansion strakes, paint and weather the hull and build the torpedo spar to be mounted low on the bow. The wooden dowel represents a support boom to which the hinged torpedo spar was chained, thus allowing it to be raised and lowered permitting mounting and dismounting the 90 lb brass keg of powder.
7/27/02 Working better but not perfectly. Still having trim problems when submerged. Porpoises wildly when tank is full. Going to try letting the dive planes have more travel to control hard dive problem. Since the deadlight holes along the top of the hull serve as vents, air may be trapped in the slight rise between them. I am going to run a bead of silicone between them to force any trapped air out the holes. I am also going to try to force as much air as possible out the stern manhole.