Neil’s Blog

Ok, so no real progress from March thru July of 2008.  However this month we’ve resumed progress and managed to get the wing pieces cut, drilled, and attached to the fuselage.  Also for the first time we get to see what it looks like with the dacron sails installed.  If you ask me, they’re pretty ugly :)  For $300 who can complain though.  We’ve been tossing around the idea of painting the center section black which may improve the aesthetics and also hide any dirt, oil, or carbon buildup from the engine.

Click on the thumbnails below for some nice hi-res shots:

The next step is to install the engine mount, and then bolt on the Kawasaki 440.  Stay tuned.

Here are the new elevators and horizontal stabilizer:

I decided pretty early on to try something new instead of using the stock Weedhopper tail section. My design has a few interesting features that should prove useful. More on those later.

Hal did all the sewing by hand on a 25-year old Kenmore sewing machine… The 3.9 ounce Dacron fabric and UV thread were bought from Hang ‘Em High Fabrics (part #’s 3.9 and T46-1-W) — we ended up spending $157 on these. There were no premade patterns to use so the dimensions were transferred directly to the fabric. Trying to get both surfaces drum-tight wasn’t easy — which is one of the reasons the tail section has taken so long. There were many other problems along the way, but the pieces turned out great in the end.

We will be using Drifter hinges on the elevator. Placing them at 45° lowers the gap from 1″ down to 0.4″, plus it allows us to ‘fold’ the elevators up for storage or transport.

The rudder is done but the fabric hasn’t been permanently installed yet. I’ll be making another small update Sunday or so to show the complete tail section installed on the airframe.

This weekend we installed the wheels and brakes. I didn’t like the stock Weedhopper setup, so I came up with the following:

Main wheels/brakes - 8″ Azusa aluminum spinner wheel & brake kit - Includes wheels, brakes, drums, tires, tubes, and hardware (Aircraft Spruce P/N 06-03410, $218.20)

The original Weedhoppers used a piece of rubber that contacts the nose wheel when you press your foot on it. I dunno, I like these brakes better :)

1″ 4130 chromoly main axle - ends step down to 5/8″ to fit wheel bearing ID. The original Weedhopper used a solid 1″ rod of aluminum. This one should be much stronger and only a pound or so heavier.

Custom nose fork - I designed it in CAD and then machined it from aluminum. It’s roughly the same shape and size as the original Weedhopper fork.

Machining the nose fork on my new G0463:

Nose wheel - 4″ Azusalite nylon wheel and 4.10 x 3.50 x 4 tire/tube (Aircraft spruce P/N 06-02600 and 06-02800, $34.00)

(the blue stuff is dykem. I need to clean this stuff off when I get a chance)

Up next is the seat, control stick, foot pedals, and teleflex control cabling. We’re hoping to have a somewhat complete cabin by March 10 or so.

Since my last post almost a month ago, we’ve had a few setbacks — mostly in the tail section. Here is an uncomplete list of the problems we’ve had:

• Design changes - The design was changed from a foldable Kolb-style to a fixed type about halfway through construction. We had to re-order several pieces, wait for them to arrive, and re-cut/drill/bend them all.
• Elevator hinge selection - There were a few heated arguments as to how we should hinge the elevators to the horizontal stabilizer. Our horiz. stabilizer and elevators are fully enclosed, and the stainless hinge brackets I picked out left a 1″ gap between them. Having no gap would obviously be better for aerodynamics but in my eyes it’s only a marginal improvement since the Weedhopper has so much drag to begin with. We eventually found a compromise that can both agree on. We’ll be using the same brackets, but hinging them at 45°, which will not only have 1/3 of the gap, it will also allow us to fold the elevators 180° to rest on top of the horizontal stabilizer when in storage. We had to make some minor modifications to the placement of the stabilizer in relation to the boom but it shouldn’t hurt anything.
• Fabric covering problems - We decided to cover the tail section ourselves (well Hal is, I wouldn’t trust myself to sewing fabric) rather than buy a professionally-made set. We saved a few hundred dollars doing it this way, but I’m still wondering if it was worth it. Trying to get the fabric drum-tight is a tedious process. In the end we found a clever way to do it… I should have the pictures of the completed surfaces in a few days.
• Time - I don’t have enough of it.
• Money - It’s not exactly pouring in :)
• I’m sure there were a few other things I’m forgetting…

Progress has finally picked up though, and I should have a lot of stuff to post in the next few weeks.

We decided a while ago to make our own fabric sails for the tail section instead of waiting for someone to make them (The main-wing sails however are pretty complicated to sew, so we’re using a used one for now). Hal (pictured below) spent a few days making patterns for the vertical stabilizer, and today sewed it up out of 3.9 oz Dacron fabric and UV-resistant thread.

Hal test-fitting the sail:

A picture of an old B-model for comparison:

I picked up a Grizzly X3 milling machine a few weeks ago, mainly to make parts for the Ultralight project.

In the next few weeks, I will be adding servomotors and ballscrews to each axis, and a computer-controlled interface powered by Mach3. Eventually it will have an automatic tool changer, high-speed spindle, rotary 4th axis, and some other stuff. Stay tuned :)

I’ve wanted to build an Ultralight aircraft for years… This January, I got my chance to start construction on one. During an evening of drinking beers and bullshitting with my neighber Hal, we decided to go in 50% each and build one. Cost would be the #1 issue on this project (besides safety of course ;). Ultralights can get VERY expensive if you’re not careful. An average kit can cost $15,000 for just the metal and fabric covering.. The engine can run another $5,000+.

The requirements for the project would be as follows:

1. Safety - Any sort of recreational aviation can be dangerous. From an engineering standpoint, material selection, load/balance calculations, and other factors must be made in the design phase. More importantly, these factors must be adhered to in the construction phase.
2. Cost - Build it as cheap as possible, while still meeting requirement #1. This rules out 99% of all “kit” planes, since these packages average $5,000 - $15,000. The only thing we had a chance of affording was a scratch-built design, based off a set of plans purchased on the internet. Luckily, there are tons of designs to choose from.
3. Portability - Most ultralights are stored in aircraft hangars, at a local airport. At my local airport, these run ~$300 per month, or $3600 per year. Fortunately a few Ultralights have been designed to be trailered, with folding wings and removable/foldable horizontal stabilizer. The Kolb Firefly has foldable wings, but the basic kit starts at $8,500 (and therefore doesn’t meet requirement #2). Another design, the Weedhopper, has foldable wings, and also met requirements #1 and #2… hmmm……
4. Ease of construction - “Simplicity” would also make a good bullet point. The easiest design I was able to find was the Weedhopper.
5. FAR-103 legal - For non-aircraft types out there, there is this requirement set by the FAA, that requires Ultralight aircraft to meet the following:
   • Weigh less than 254 pounds
   • Have only 1 seat
   • Have less than 5-gallon capacity fuel tank
   • Not capable of more than 55 knots
   • Stall speed less than 24 knots
   • Used for recreational purposes only

   There are several designs out there which meet the cost, safety, portability, and ease of construction requirements, but unfortunately do not meet FAR-103. The Affordaplane was designed to meet all of these, but they’re really hard to get under 254 pounds. Back to the Weedhopper, they almost always fall under 254 pounds, so no problem there.

So after months of research, it was decided that the Weedhopper best fit our needs. The only downpoint was the quality of the plans. The set I picked up on Ebay were originally drawn in 1970, and full of errors. I decided early on to redo the drawings myself, in CAD. Every piece would become a 3-dimensional model on my computer, added to the main assembly, and any errors in the plans would show up immediately. In a few months when the drawings are complete, I’ll post them on this site for free.

A few pictures of completed Weedhoppers:

Blade Doyle’s Weedhopper:

Dean Scott’s Weedhopper:

Keith Murchison’s Weedhopper:

Below is the progress we’ve made on the plane up until today. The entries are listed in reverse-chronological order, since Wordpress lists the rest of my posts that way. So start at the bottom and work your way up.

2/03/2008: Fuselage mock-up

Today we did a mock-up of the fuselage. Surprisingly, everything just bolted together without any real problems… I was almost certain we would have to re-bend or re-drill something.

Unhappy mom:

She doesn’t like the idea of her son flying a deathtrap :)

1/30/2008: Fuselage construction

Fuselage construction begins!

My custom CAD plans:

Fullsize template:

bending jig:

Vee-block jig:

Me, making some measurements:

Whoops - misaligned boom holes. Don’t expect the drill bit to exit the bottom where it needs to be. Learn from our mistakes, and drill the top/bottom separately. Wrap a piece of paper around the tube, then fold it in half to get the opposite hole. Drill the top, flip it, then drill the bottom.

1/21/2008: metal arrives

The metal showed up today after being back-ordered for almost 2 months… This is probably the last time we buy metal from Aircraft Spruce :(

1/12/2008: Picked up a used set of sails

We picked up a used main-wing sail from Rick on the Weedhopper group. The final cost with shipping was $323. To contrast, a new main-wing sail costs around $1200. We will have to make a few patches here and there, but overall it seems to be in great shape.

Not my first choice of colors :) We’ll probably use these for a year or so, and eventually sew one from scratch or order a new one at full-price. We’re still not sure on the color scheme, but I would like to the Red Baron scheme, like in this picture.

12/18/2007: Plastic pieces arrive

Since the Weedhopper factory has been out of business for quite some time, getting replacement parts wasn’t easy until Scott McClure started making them. We pretty much bought a few of every piece he offered:

• Saddle Washer kit - $17.95
• Contoured rib tip - $2.00/ea
• Raised rib clip - $3.00/ea
• Wing tip block - $7.00/ea
• 2-1/2″ tube end - $5.00/ea