Wed Aug 8, 2001

1 hour

Pictured top right - This is the craft with the thrust duct former illustrating where the duct will be.  This is the inside diameter of the duct.  The actual duct will be 4" larger.

Pictured 2nd right - This is another view of the craft showing how big the duct will be.

Pictured 3rd right - I fiberglassed the inside of the engine mounts all the way along the deck with 6oz glass.

Pictured 4th right - I finished filleting the lift duct fan mounts.

Thu Aug 9, 2001

1 hour

WE HAVE IGNITION!

Today I picked up the rest of the engine gas line fittings and a new fuel filter.  Lucky thing I did. The existing fuel filter had a crack on the back and would have leaked all over if I tried to use it.  I also bought some wire and throttle cable.  I hooked everything up and fired it up.  All I can say is awesome.  Started easily and ran great!  Doesn't quite sound like I expected... I was thinking more lawn mower but it has a deeper sound.  Better.  Vibration wasn't too bad either.  I feel better knowing when I go to fire this bird up for the first time that I won't have engine troubles.  Very happy...  If you have a new engine make sure you check if it comes with oil in it.  Mine didn't.  It took about 1 litre of oil.  Because my engine is on an angle I filled the oil when it was on the ground level.  I lifted the engine onto the craft again myself.  I think I am going to get a hernia (SP?).  The engine is about 110lb's and is awkward.

Pictured top right - I left the 6 gallon fuel tank on a table beside the Hovercraft... wanted to minimize possibility of leaking gas on the hovercraft.

Pictured 2nd right - I bought a fitting for the tank and a boat engine style quick connect for it.  I did it this way so I could remove the tank for refueling.  Also I did it so I can have more than one tank.

Pictured 3rd right - I found the throttle and choke controls.  They were located on top of the engine under the air cleaner cover.  The one with the cable on it is the throttle.  I did not hook a control to the choke yet so I adjusted it manually.  The choke is the one right beside the throttle on the other side of the engine. Didn't seem to be to fussy when I started it.  I don't know which way is open and close yet.  I think this engine is different than the Kohler Command version.  This engine is a pro version.  Dave or Greg is this where your throttle and choke are located?

Pictured 4th right - This is the Kohler wiring harness and the throttle control.  I bought the throttle control at Canadian Tire for under $5.

Pictured 5th right - I used jumper cables and connected the negative to the engine hoist mount and the positive to the solenoid.  It is the one with the purple and red wire on it.  I have wiring diagrams if anyone needs them.  The other end of the jumpers goes to the battery on my motorcycle.  If you look closely you can see it run there.

Sat Aug 11, 2001

Yesterday and again today I tried running the engine with the lift belt on.  Wow does the belt ever flap all over the place like crazy when the engine is running slower.  I checked my belt tension and it is 8lbs.  In the book it says it should be around 9lbs.  It feels pretty tight to me.  I couldn't believe the belt didn't jump off the engine sheave.  This was yesterday.

Today I decided to fit the belt guides/guards to the craft.  I went out and bought 1 1/4" PVC tubing and cut it to two lengths of 54".  I then cut the lengths in half as per plans.  I built the guard mounts and a temporay jig to hold them in place.  I ran started the engine.  It seemed better.  I ran the engine for maybe 2 minutes.  I took the guards off and looked inside to see if the belts were rubbing - yes they defiantely were.  On the inside of each tube there were black marks where it rubbed.  I expected this because of the way the belts flapped at lower engine speeds.  I am not sure how this is going to affect belt where.  I am guessing this is normal but I am still not very happy about it.  I decided to try removing the guards and putting another set of idler pulleys in the center of the long span.  This didn't work the belt jumped out of the pulley right after I started the engine.  If I try and raise the height of the pulleys they will put the belt out of alignment with the engine sheave.  I am not sure what to do now. I have little experience with this type of setup and am not sure if this is normal.  I am starting to wonder if I should have put an engine in the front instead of running the belt...

Pictured top right -  The belt guards in place.

Pictured 2nd right - Another view of the belt guards.  Hose clamps are used to hold the cut pvc pipe together. Also note the jig holding it is temporary.

Pictured 3rd right - Shows how the belts are centered.  Note the slot in the pipe mount to put the belts into position.

Pictured 4th right - I took the mounts off after running the engine for a couple of minutes to inspect the insides of the tubes.  The tubes on both sides were making contact with the belt.  I may coat the insides of these tubes with epoxy mixed with graphite to reduce abrasion.  The epoxy probably won't adhere to the pvc though...

Pictured 5th right - a closer look at the rubbed area.

Pictured 6th right - The mid span idlers that did not work.  The belt jumped out soon after starting.

Sun Aug 12, 2001

6 hours

Today I had a fellow hovercraft builder over too look at the craft.  I ran the engine for him so he could see the belt flap.  He didn't think it was that bad... good I feel better now... On to the thrust duct!

Pictured top right - a view of the lift belt going to the engine without the guards on.

Pictured 2nd right - I drilled a 1" hole through the thrust duct former center.  I drilled half way on both sides.  The holes met perfectly in the center - lucky.  I used a Black and Decker workmate vice to hold one end of the steel shaft I pounded through the 1" hole.

Pictured 3rd right - I made a brace using 2x4's to hold the other end.

Pictured 4th right - I drilled a 1" hole through each 2x4 and used a rubber mallot to armstrong it on to the shaft.

Sun Aug 12, 2001

Cont...

Pictured top right - My duct former was 1/8" too short in diameter.  I used 1/16" formica cut 5" wide and brad nailed to the formers to make up the difference.

Pictured 2nd right - I cut 4 sheets of 1/8ply to 4' x 13".  I brad nailed the ends of each sheet onto the former and left one sheet overlapping the other

Pictured 3rd right - A lot of glare here... I am trying to show how I used duct tape to form the outer edges round.

Pictured 4th right - The 1/8" ply duct wall is wrapped and held by the brad nails so I can apply fiberglass to the joints.  I put plastic under all 3 of the joints to be fiberglassed so I can easily remove the ply without it sticking to the formica.  Notice how I didn't run the fiberglass completely across the seams.  I did this because I am hoping the foam that makes up the outside of the duct will naturally round these joins.  I am going to remove the ply after the fiberglass and epoxy cures.  I wanted to wrap it around the disc former because I noticed with the thrust duct when I pre joined the sheets on a flat table the joint wanted to stay flat when I bent it around the lift duct former discs.  After I remove the ply from the disc I will pull the brad nails out.  I will then wrap it around the disc again and mark the 4th joint so I can cut it.  Once it is cut I will use ratcheting tie down straps to hold the thrust duct while I epoxy the final joint.  I can't sacrifice the tie down straps this time so I will wrap them in plastic and fiberglass around them. 

Mon Aug 13, 2001

2 hours

Today I cut the plywood thrust duct sheets, and epoxied the final seam together.

Pictured top right - I used two ratcheting tie down straps to hold  the ply tight to the former discs.  I put plastic underneath the straps where the last seam is. 

Pictured 2nd right -I put two layers of 6oz cloth on the inside of the straps on the seam.  I put one layer of 6 oz cloth on the large outside part and 2 layers on the small part near the front. 

Pictured 3rd right - You can't really see this but I brad nailed a piece of scrap wood to the inside of the 4 seams on the edges fartherst away from the formers.  This helped keep the plywood round near the edges.  I then fiberglassed the outside of all the remaining 3 seams on the large end on the straps. 

I can't think straight... I think I inhaled too much OFF!  The mosquito's here are really bad now... Man I hate those little buggers.

Wed Aug 15, 2001

2 hours

I cut out the two pieces of foam today for the thrust duct.  I used 2 2'x8' sheets.

Pictured top right - shows the pivot point for the 1/16" wire I used to mark the two arcs. One with radius 245.25" inch and the other 263.25"

Pictured 2nd right - This is the distance to the foam.

Pictured 3rd right - Here is the first one cut.

Pictured 4th right - After I sanded it I used it as a template for cutting the next one out.  I clamped the two together and sanded them to the same size using the one I marked as a guide.

Thu Aug 16, 2001

Today I sanded flat and filled some dents on the outer surface of the foam which will become the duct outside. 

Pictured top right - I marked the lines from 1.5" from the edge.  Fiberglass will be applied to the remaining 16.5" of the foam.  I will be using 4oz cloth as recommended by UH in the Construction Book.

I am interested to see how many people are following my progress.  If you regularly check here to follow my progress please send me an email and let me know by clicking on my email address on the bottom of the page.

Fri Aug 17, 2001

1 hour

I built a hot wire bow system today.  I used 1" dowel and a 2x2 with some hardware to construct the bow.

Pictured top right - the completed bow.  Made from 2x2 and 1" dowel.  It is spring loaded.  I used a spring from an old swing lamp.  It isn't strong enough to put enough pressure on the wire.  I will have to replace it.

Pictured 2nd right - 120VAC to 24VAC transformer.  I need to add a dimmer to this so I am not running it as a short circuit.

Pictured 3rd right - I used the following hardware for the tensioning mechanism.

Pictured 4th right - Here is the other end where the cutting wire goes.  I used some 36" fishing leader line.  It cuts foam but I don't know if it gets hot enough.

Pictured 5th right - Here is how I attached the power wires to either side of the hot wire.  This is just temporary I will solder some aligator clips onto them

Sat Aug 18, 2001

3 hours

Another blisteringly hot, mosquito infested day.  I fiberglassed the two foam arcs that will make up the thrust duct.  I removed the engine and lift belt from the craft and had my wife help me turn it upside down.  I need to do a few more things to finish the bottom.  I need to fillet the inside of the landing skids (done today), add the airsplitters and fiberglass in place, fiberglass the outer skirt attach strip to the foam, reinforce the bow with fiberglass, seal the rear inner attach strip with epoxy, seal a seam inside the inner chamber, and attach the 1" x 1/8" aluminum strips to the landing skids for protection.  I am pretty sure I will use the aluminum as I want to ensure I protect the wood well.

Pictured top right - I am preparing the foam arcs for fiberglassing.  The last 1.5" closest to the duct leading edge is supposed to be left foam at this point.  I applied duct tape to this area after marking the 1.5" strip using the same jig I used earlier on in construction to mark the foam riser base ply plate.

Pictured 2nd right - Here is one arc completly fiberglassed.  I used on continuous piece of 4oz cloth and removed the tape just after I applied the glass.

Pictured 3rd right - Both arcs completely glassed on one side as per plans.

Pictured 4th right - I flipped the craft upside down and filleted the inside of the landing skids with epoxy mixed with microfibers to peanut butter consistency.

Pictured 5th right - This is what the lift duct looks like upside down.  Note the lack of air splitters on either side.  I will add these shortly.

Pictured 6th right - This is what the craft looks like upside down for hopefully the last time.  Once I get the 54" thrust duct mounted I will no longer be able to turn it upside down.

Next steps.... I will complete the work to the bottom of the craft and then construct the skirt.  This way I will be able to hover the craft in and out of the garage.  It will also be easier to construct the skirt with it upside down.

Sun Aug 19, 2001

10 Hours

Today started our crappy.... the arcs didn't seem to be the right size for the duct when I first test wrapped.  It turns out they were close but not quite right.  I was able to use them anyway.  The duct is longer at the seams.  Not a big deal I can fix it easily enough. I will probably leave it with one seam at the top and one at the bottom.  It isn't really noticeable.   It is an interesting task building a thrust duct.  Make sure your measurements are dead on.  That cable I used to mark the radii didn't work very well.  When I build another one I will use a solid wood jig to mark the arcs.

Pictured top right - Yikes over 100 cuts per arc!  I used a dremel with a small drill bit and router attachment.  I set the depth of the bit at 1.5" as per plans.  The plans call for cuts every 0.5" for the first six inches of each arc and every 1" for the rest.  The dremel worked well but made a terrible sound.  My wife came out and told me it sounded like I was strangling a cat.

Pictured 2nd right - I used a hot wire to cut the wedge in the arc.

Pictured 3rd right - Test fitting the foam

Pictured 4th right - Here is the foam arcs ratcheted to the duct.  I decided not to join the two pieces.  I am going to put them on the duct one at a time then ratchet into place.  I sanded the basic inlet shape into the foam.  I will finish sanding it once it is mounted to the duct.  I am not sure how hard this will be... not sure what kind of sander to use either.

Pictured 5th right - This is the view from the back.  The trailing edge is only 1/8 of an inch thick. 

Pictured 6th right -  I marked each half of the plywood duct where a foam arc went.  I mixed epoxy and microballoons to a paint consistency and applied to one half of the plywood.  I then wetted the foam arc with the epoxy and microballoons.  I positioned the arc onto the plywood and used a quick clamp to hold it in place at each trailing edge.  I repeated the steps for the second foam arc.  After both arcs were in place I used the ratcheting tie down straps to hold the foam in place.  If you look closely you can see a black tool box holding the foam arcs down at the top join.  I will fiberglass the join later. I didn't fiberglass it before because it would have been to hard for me to put it on by myself.

Mon Aug 20, 2001

10 hours

Well today I accomplished a few things... not as much as I hoped.  This was due to driving all over the place picking up things I needed.  I attached the aluminum strap on the landing skids and sanded the thrust duct.

Pictured top right -I I used 3 8' lengths of 1/8" x 1" aluminum strap to cover the landing skid bottom.  Here I am trial fitting the curve.  The process was to clamp the strap on and mark where the skid starts to bend.  I would then take it off and cut a slit 3/4" where I made the mark.  The cuts start on the part of the strap closest to the interior of the craft.  I repeated this fitting and cutting procedure till I had the strap laid out for the entire craft.

Pictured 2nd right - Shows the second strap fitted.

Pictured 3rd right -  A close up showing the slits used to bend the strap.

Pictured 4th right -fitting the straps for the other side.

Pictured 5th right - After all the strap was cut and bent to shape I counter sunk holes in the skid for a #10 x 1 screw(one on either side of a slit and join and one on each end plus some additional at the rear).  A note about drilling and aluminum.  I used a countersinking drill bit (actually 3 different kinds).  The drill bit kept getting stuck and it wasn't cutting the aluminum.  It was starting to drive me nuts then I remembered being at the metal shop and watching them cut metal... it was all oily when I got my pieces.  Ahhh... lubrication.... I then found a can of silicone spray and sprayed it on the bit and the strap.  The strap was much easier to drill with the countersink bit. There is probably a better oil to use as a lubricant but silicone worked ok.

Pictured 6th right -  A close up showing the counter sunk #10x1 stainless steel screw.  A word about hardware stores and their buld screws.  They suck!  I bought 80 Stainless Steel screws at $0.23 each = ~$20.  When I got home I found 1/4 of them were not stainless and some of them weren't even the right screw size or head.  Arghh....

Pictured 7th right - Here is a picture of the thrust duct taken just after the sun went down.  I need to sand it to shape and fill some dents.  I bought some lightweight filler and some safety gogles today.  I didn't have any glasses when I was sanding today and styrofoam kept getting in my eyes.... really annoying.  Wear a mask to as inhaling the styrofoam is not fun either.

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