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my new prop...

everybody kind of testy here huh. LOL kinda like the movie grumpy old men, I don't know about leo but olfart is old and grumpy LOL but we still put up with you ken... now if you were as handsome as I am then life would be easier LOL

everybody take a deep breath I used to get censored for less than what ya'll are doin on here, my how times change ... just kiddin rick

Ya'll have a good weekend I am off to crystal river and maybe swimmin in the springs or divin up a scallop or two or maybe even a brew or two LOL well a diet soda anyways or a coffee. be good and don't kill each other .. Ken if you would get that boat running it will help with the anxiety issues.
 
This may go down as the most read thread in the history of the Forum.

Leo I have some questions relative to the chord of the prop blades but no time to ask right now, off to work. Likely Monday before I have much time.

Yall have fun

Scotty
 
We have a LOT more choices now than we did back in the earlier days. Initially I remember constant chord props then as wood props evolved they got a bit of shape to them and narrowed a little at the tip. Now that we got plastic involved we see huge whide chord in board and narrowing to thin at the tips.

Is this for noise abatement or for preventing the tips from stalling in a turn or what? Aestheticlly I think the look terrible but is it functional or marketing?

I guess it has something to do with equalizing stresses over the length of the prop maybe? Generate more thrust where the blade is thicker and less where its thinner?

Props are mysterious to me. I do understand how a wing works and in a plane I really like the performance of the constant chord Hersey type wing. Especially in stalls, its a clean crisp break compared to tapered wings that prolong the shakes and buffets til they finally stall.

But that is all low speed and Im guessing props are shaped for higher speed?

Just out of my realm of knowledge. Any comments will be muchly appreciated.

Is the spelling is cord or chord?

Scotty
 
Whitebear I beleive the shape of the new sensenitch props are designed to dissapate the tip vortexes somewhat. I know I can't spell leo LOL. The same things were done on wood props by hand many times. there is one story of a prop maker in central florida who worked on a contract for the governemnt to quiten down a prop for surveilance aircraft. he made the prop then put it on the plane and it took off then landed and he whittled it with a pocket knife, honest thats the story, until he got it quiet. They then duplicated it. It could be done to any of the props but it costs money an dno one wants to spend it to buy one ... yet but times are a changin.

oh yeah it is chord
 
WOW!!! wasn't trying to start a brawl...lol. anyways, i've been struggling with a cylinder problem for a few months now, so, my boat is running like crapp. dang thing is fouling and popping all the time......very irritating. but, i've got a new cylinder in and will be putting it on next weekend. thinking of upgrading to the LS1 after i get my 0540 running like a top again......anybody interested in an 0540???
 
Great response, now were getting somewhere.

"And did you know that the props in our airboats are the least efficient props in application??? Ask your prop manufacturer about this..."


Is this because of our length limitations due to the safety cages? I have never liked a long prop on my boat, even knowing I am losing some push. I am not alone here.

When I was making DD carboats we sold them with a 70' prop and even at that time I liked a 68' on my boat. I have however run the big seismic redrive carboats with 78" wood props and didn't have any problems, it was always in the back of my mind.

Scotty
 
Now were gtting somewhere. I had long ago looked at ducted fans as being more efficient than our props but what came to me is the close tip clearances needed and the beating we give our boats. It isn't likely we could marry the two. So I guess were stuck with the inefficiency levels.

Scotty
 
I've seen them on hovercraft but there again hovercraft dont take the beating we give our airboats. I "think" I remember seeing some ducts moulded into the body of some smaller airboats with way low HP. Not sure they were true ducted fans or just shrouded props.

I think the redrives are about all the added weight we can stand now with the state of the art as it is. I just don't know of any practical way or material to use to make it for a full scale day to day knockabout airboat. Llikely neither does anyone else, thats why we don't see them out on the market for us.

For the noise concious though, ducted fans would definately reduce prop noise considerably. I have seen them on a BN2 Britton Norman Islander airplane that has 2 300 HP Continentals on it and the noise reduction was NORE then just noticeable. It bordered on incredible.

Sure is something to think about though.

Scotty
 
I'm trying to remember where I said this "IF THEY DON'T COPE UP WITH THE REQUIREMENTS, THEY WOULD JUST GO ON MANUFACTURING DIFFERENT PRODUCTS".
but I can say with 100% confidence that every person who I have ever helped or has purchased a motor from me will say I treat every engine and combination as an individual if I was a smart marketer I would convince everyone their is one product for all your needs that's how you make money. However to me each application is different so each power plant is different. I will not do mass production thus I will never be a successful business in an entrepreneur eye's, however at the end of each project I know I tried to make it better then the last one. In the business world the engineers love crazy things that haven't been done yet that cost a ton of money to develop and they really love showing off their superior intellect buy coming up with ideas that are not economically viable or the technology for manufacturing is not yet available, marketing only cares about something that can be mass produced and marketable and manufacturing is only concerned about building it right and keeping things less labor intensive, we will not get into management. The smart person is one who comes up with a product that is possible, affordable and there is a market for it. From a technical point of view we all know an airboat needs a shroud and the right prop dia. We all know there are a 1,000 thing that we can improve on these boats but remember air boaters do not tend to throw down thousands of dollars for something new. The airboat manufactures and prop manufactures know this. The ones who tried new expensive ideas that there was no market for are no longer in business. In the last ten years I have heard OVER 20 PEOPLE RANT AND RAVE ABOUT SHROUDS, how come nobody has one. I mean common why don't somebody just shell out the half a million dollars and thousands of hours to do it. You know why, the weight, the cost and there is no market for it come on 90% off air boaters are still complaining about having to spend $250 for mufflers. The prop problem is being solved by a business that must make money so they are manufacturing things that have a market and will be bought.
 
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