Project From EmptyNester - Belt "guide" for hovercraft

(This doesn't count for the contest since I already have a project in this category, but here it is anyway.)

I haven't gotten the hovercraft's drive fan belt working totally yet. With a design speed of 50 - 55 mph, I've only been up to 17 mph. Which is in fact scarier than you'd think when you're trying to learn to fly the thing and be a test pilot at the same time:O

I've had lots of issues with the belt coming off. To try to address this, I added a piece of HDPE to hold the belt in and act as guide.

Attachment 8145

On the last test I had a lot of problems. One was that the belt actually turned inside out on the drive pulley. I was surprised it even stayed on. The HDPE didn't help, it just burnt through. That piece of HDPE doesn't have more than 30 minutes of run time with the wear shown in the picture.

Turns out that I had an issue with the idler pulleys. They were binding in the track. When they tightened up, I got the impression the belt was tight, but it was actually just the pulley binding. I've fixed that, but I'm still concerned about the belt twisting due to flapping. I thought using something to dampen the flapping might help.

I finally came up with a simple solution that I hope will work.

I used a piece of 2" x 1/8" bar and a 2" long piece of conduit. (I am careful about ventilation when welding conduit.) I MIG welded the conduit to the bar and plan on mounting that on the inside wall to reduce the belt flapping as it approaches the drive pulley.

Attachment 8147Attachment 8148Attachment 8149

I haven't mounted it to try it yet, but picture below shows how it would mount.

Any thoughts on how this will work? It seems like it shouldn't be dangerous, but I'm not sure how effective it will be.

Attachment 8150

Given the quick cold snap, I may not be able to test it again until spring.

Hi EmptyNester,

Looking at your first picture, I was wondering if you could use a mechanical gearbox, the kind found on an appropriately sized snowblower auger, for the 90 degree power rotation from the vertical shaft engine.

Then a length of shafting to line up the driver and driven pulleys, a belt tensioner (as on a car) and voila, shorter belt, no twist no flap.

Just my 2 cents.

rivets

The belt path reminds me of a Corvair engine, which also would like to throw belts, especially when modified. Your anti-flap parts might cause a little bit of belt wear, but I'm sure that won't be an issue for a while. If it works you can always add some smooth idler pulleys for belt control. Getting proper belt tension will be important, and you may have to re-tension once things warm up.

Hi Nester
Have a Talk with a Gates Rep.
and maybe use a double "V" Belt = Single Belt "V" on Both Sides

Rivets - I've seen some posts on the hovercraft web sites about people going to drive shafts. It appears to be difficult to get working. I'd like to get it working to the plans before I starting "tinkering".

Rambozo - I had thought about an additional idler pulley but was't sure how to do it because I figured it should be spring loaded. I hope that fixing the existing idlers will take care of it the problem, but putting something in for antiflap and new HDPE seems like it would increase the chances of success.

Scotty - I hadn't heard of double V belts before but they look pretty cool. That seems like it would make belt twisting a non-issue.

Well, first thing I'd try would be idlers at 45* to help maintain the transitions, you could even oppose them with a flat idler to 'capture' the belt. This brought upon another thought, what about a flat 'idler' in place of the HDPE, a heavy duty bearing even, at the entry points where the belt first meets pulley.