Finally got time to work on my airboat. Here some pics of the new redrive I'm just finishing up. Powdercoated flat black. Due to the cam this will be a 2 to 1.
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Finally got time to work on my airboat. Here some pics of the new redrive I'm just finishing up. Powdercoated flat black. Due to the cam this will be a 2 to 1.
rbengines,
It's looking very nice. Time and money. Hmm... we never seem to have enough of either.
Why is that?
About the 2:1 drive. :eek:
From everyone that I've talked to, you DO NOT want a reduction drive that is "exactly" a whole number reduction. This is because of resonance problems. Make it a 2.1:1, or a 1.9:1 reduction. Or some other close variation.
But an exact whole number reduction drive has caused a LOT of people a LOT of grief. I know that it makes the math simple, but still...
With a whole number reduction, things "hit" the same point, at the same time, over, and over, and over. :eek:
Looks like you are well past that decision point.
I sure hope that it works out for you.
Now, in a well balanced situation, it has also worked out nicely.
I'll keep my fingers crossed for 'Ya.
Please keep us posted.
Thanks,
Duane
Edit: One way to help REDUCE the "resonance" problem is to use an odd numbered prop. For example, a 3 blade or 5 blade prop, instead of a 2 blade or 4 blade prop. Just something for you to think about.
Where could I find a drive like this one, I would assume that there`d be no slippage on this reduction, I interested in putting one on a 084.
rcm243,
Contact Arrow Prop at http://www.arrowprop.com/ or call (405)279-3833 and ask to speak to Don Miller.
They are the only ones that I know of that build a ready to bolt on reduction drive for the 4A084. It doesn't use a true timing belt/cogged belt, but instead uses a banded cogged wedge V-belt.
It can be argued which is better. A true timing belt/cogged belt can NOT slip without either jumping or breaking teeth on the belt. On the other hand, a banded cogged wedge V-belt CAN slip a little when it needs to. (Like during sudden acceleration.)
Good luck, and let us know what you decide. ;thumb;
Thanks,
Duane
Duane, I talked to Don at Arrow and it looks like I`ll be buying one from him, do you think some sort of spring loaded idler on this set up would be a good way to keep tension on the belt? It wouldn`t be hard to do. I`m not sure as to what prop I`m going to use on this boat,its a 13ft. by 78in. glass hull and its a little heavy at 250 pounds,I may buy one of Arrow`s 3 blade composites, any suggestions? Bob
Bob,Quote:
Originally Posted by rcm243
Hmmm... I hadn't even thought about using a spring loaded idler. No, it would NOT be hard to do. They're used a lot of times in industrial applications. I really don't see nothing wrong with that idea, but I've also never seen it done in our application.
It's really not a bad idea...
The good news is that it'd be one of those things that you could add, try it, and easily remove it if it didn't work.
Just make sure that if you DO try it, you put it on the slack side of the belt. It does not work at all if its done on the tight side. (Don't ask how I know this.) :&&:
I don't know about the prop. Arrow Prop has an excellent reputation in the ultralight / experimental aircraft field. They are not as well known in the Mini Airboat field. I've not heard anything GOOD or BAD about them in our application.
I looked at Arrow Props composite props, and considered buying one. My decision to go with a Whirl Wind Mini Prop was almost decided by a toss of a coin. I really don't remember what pushed me to the Whirl Wind side. (I was looking at a LOT of options then).
I really don't think you'd be WRONG in going with an Arrow Prop composite. I think that Don would do whatever it takes to make it work for you if you had a problem.
Good luck with your decision,
Duane
Just how does the Arrow reduction belt stay tight? Is it so close to a tight fit that it doesn`t have much slippage? I looks to me that there has to be some way to keep it tight I guess when I lay my hands on one I`ll find out, but the idler would be a good way to do it, could probably take a serpentine idler off an old chevy 4 cyl and make it work. Bob
Bob,Quote:
Originally Posted by rcm243
I guess that the correct answer is that it doesn't stay tight. The banded cogged wedge V-belt helps, of course. But even it does require periodic adjustment to limit the slippage.
That's why a spring loaded idler may be a good idea.
Keep in mind that an airboat is not like what we've come to expect from our daily driver automobiles. They just go on and on like an EverReady Bunny. (Well, hopefully so.)
But, every time that we put an airboat in the water, we should do an inspection to make sure that it's ready to go. One of those inspection items should be the condition and tension of the reduction drive belts.
In that respect, an airboat is similar to an aircraft. Example: If your car runs out of gas, then you're stuck on the side of the road. But if your airplane runs out of gas, then you may have a serious problem.
Same thing with airboats. We need to inspect it before we go for a ride. One of those inspection items is the drive belt, it's condition, and it's tension.
That's where your spring loaded tensioner idea has merit. It doesn't mean that it should be overlooked, but it does mean that many times it should be OK.
Duane