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Killer new prop

Waterthunder

Waterthunder

Well-known member
For a while now we have been bitching that none of the prop manufactures are trying new technologies and designs to make props quieter. Well Sensenich has, I tested their new Q ultra wide series this prop is incredible. It did everything better than any prop I have ran accept one thing. Here are some performance specs one reason my boat gets incredible fuel economy is it planes at 2,300RPM and cruises fast at 2,800RPM well with then Sensenich it planes at 1,500RPM and cruses at an incredible 1,900RPM my fuel economy is going to go thru the roof! Also I never heard this prop over my exhaust this prop is quieter than any prop I have ever ran. Something else that is cool it has a sweet spot that is like pulling second gear or hitting N2O this prop also has more top end than any prop I have ever ran. The only down fall is I lost two boat lengths in a 400ft race against my best combination it's good for racing but it isn't the best. It grabs so much air and the size of the blades I believe inertia is causing the boat to torque roll severely no other prop I have ran has done this on my boat it takes 60 feet or so for the boat to quit ridding on it's side. However I will give up two boat lengths in a drag race for everything else. This prop is a winner and a blast to drive top end. So it has more push, better fuel economy, lower cruising RPM's, lower planning RPM's and is very Quite along with an insane top end. I know you guy's have heard me preach the 2.68 ratio gearbox for years well with this prop I don't think nothing else has a chance at this point in time. I know what is next how about a higher gear box well I have tested 3.23 boxes with these wide props and they just don't work as well I don't know why I think it's like everything else there becomes a point where you go to far. Kind of like a sprint runner running down hill. Anyway I will be running this Sensenich prop at the quite airboat expedition.
 
Yeh man, now were getting somewhere ! Im really glad they deveoped that one. I knew something like that Q series would be a BIG advancement.

What RPM is your engine turning when the Prop is at plane and cruise speed? I'm really curious about your RPM statements, do you have a prop tach or are you calculating solely from an engine tach and the ratios?

Sounds like you might be a real competator. You go man !

Scotty
 
Sweet ...... sounds like Sensenich has found the combination :D .
Lookin forward to seein it run. Did you get the three blade?

BF
 
My plane RPM and cruise RPM are based on engine RPM's so I plane at 1,500RPM that's 559 prop RPM that is why it is so quiet when I take off you don't even hear the prop over my exhaust, my cruise is insane at 1,900 engine RPM or 708 prop RPM. I passed my buddy and would leave most people behind at their cruise RPM. This thing is cool I can't wait to bring the Hill to it's knees it's getting very dry and in the summer only a hand full of boats will make it to the tree line this prop will flat out push.
 
It's a three blade ultra wide the tips are far superior to brand X instead of epoxy being shoved in the ends the whole end is laid fiber the prop looks really robust and safe. I will be playing with it all this week trying to bring the 400ft around and will be racing some super charged race boats Sunday along with some N2O boats. I will keep you all posted guy's I really think if they force the noise issue or make us adhere to the same standards as everything else we can meet it and still have our performance this is what we need.
 
OK so what RPM does the engine idle at, and at idle will come anywhere near sitting still in the water. I know most boats really dont sit still idling but is that thing still trying to make headway at an idle say in deep water?

This all fascinates me cause your back down in the engine RPMs we used to see on the DD Buicks and in fact your operating below that. This gets more fascinating by the minute.

Is it tractable enough to make a decent frogging combination?

Scotty
 
Don't be selling your prop quite yet rick ,thunders right the new sensinch prop is real quiet , at a low rpm and has a lot of thrust down low around 1600 prop rpm ,at higher rpms around 2000 thay aren't any quieter than brand x and produce no more thrust at higher rpms than brand x. The trick is to put some reduction behind your engine and turn the prop real slow example an engine turning a 5000 rpm maximum would want a 3.12:1 gear box , 4800 rpm 2.88:1 , 4500 rpm 2.68:1 , 4000 2.38:1 this prop needs to turn slow to be effectively quiet, other wise it is just as load as the rest. Also with the proper reduction it idles no faster than the average airboat.Engine cruise rpm wood be abought the same also.
 
basically with any prop... you need to run them how they are DESIGNED to run. The ONLY way to make a prop quite is to slow it down. You can make any prop quieter by slowing it down. But most don't perform well when you slow them down. Now Thunder needs to lower his exhaust signiture and he'll have the first stealth airboat.
 
I'm sure a dd car motor can't swing this prop I doubt even a two blade. And if it did it would be going 20MPH at idle. I know my boat yesterday no matter what RPM I turned it was quieter then any other prop I have ever ran. I had several people comment how quite it was. As for the gearbox if you got to run a 3.23 to run a prop it ain't worth it. I tested 3.23 gear boxes they have two inherent problems the main one is to achieve that ratio with the present box's dimensions the gear get's to small and narrow I have broke them in one day's time. A 3.23 is good for a V6 but anything over 500HP you will break a gear I ran into this problem four years ago. Also the boat ran slower sucked out of the whole and had little response due to the slow velocity of the prop. After I broke another 3.23 in 20 minutes I gave up. I have never hurt any other box even with a 1,500HP two stage N2O big Block or a 600HP small block with a clutch being dumped at 6,000RPM. I just wanted to share this info about this prop I'm very happy with it. I do know on my boat with the set up I have this prop performs the best and most efficiently and is the quietest.
 
Dan, there will be ways to quiet a prop without slowing it down too. We just haven't found 'em yet.

You're right, under most existing conditions slowing a prop makes it quieter and you DO lose efficiency because it was designed to turn faster in order to make max. push. That's old aircraft thinking. The new technology, like the prop Thunder is running, is designed to work harder at less RPM.

Nobody ever complains about the amount of sound a light airplane makes because time has taught people to expect that from an airplane. That's one reason why attacks on airboats are so blatantly unfair.
But we still have to try because we, not the aircraft industry, are the people under attack.

BF
 
I believe in the Q blade props. We run one on our dd olds boat and it is incredibly quieter at cruise than the old wood prop we used. I was just meaning that the prop manufacturers are seeing the need for slow turning hard pushing props and now Sensenich has put out a prop that does exactly what we need. If I had the funds I'd order one for my other boat and put a 2.68 gear box on it. I'm just glad someone is testing them and telling us how they work. Keep up the good work. Isn't basketcase using them on his counter-rotator as well? They only way we can learn how to quiet them down is for people to try the new products out to their limit and post the results. In my first post about turning them slow is that the prop is probably designed to turn 2000 rpm or under and if you turn it faster you are out of the desing of the prop. It like turning a wood prop to 3300 rpm. Loud as can be.

Keep up the good work guys. I learn something new every day.

Dan
 
I have no interest in high speed or racing, however, running dry and slow frogging is what I like. If I can't idle and sneak around the shore or marsh it isn't for me.

I think this Q series, though, may have something for me. If not the wide blade the regular one. I'm still looking at light weight and aircraft but that SL1 is fascinating me more and more as I learn about the RPM range and fuel consumption.

For me this is a learning process, I won't learn it all in one single step. Takes a lot of time for me to digest idas and numbers then do the math then sit back and see how I FEEL about it. Maybe even do it over and over multiple times and sit back and FEEL some more on it. Sleepin on problems and issues takes time but does produce results for me.

So as I said, I am fascinated by this.

Scotty
 
I found an ad on airboat trader for a boat with a 5-blade sensenich narrow blade carbon prop. Has anyone thought of trying the origional q blade in a five blade configuration for belt drive low hp engines? I wonder if they would be quiet and still push? We love our q blade it is a 74" on a dd 455 olds that is stock except aluminum intake and edelbrock 600 carb. It pushes a bunch more than the wood prop and is quieter. It does have a whistle to it when idleing. It's kid of cool. I ran it on my stock 500 caddy for a while to and it worked just as good on my light boat as it did on the heavy antique that our other boat is.

They are on to something in the tip design. I have a whirl wind sp prop now for my caddy boat to see if I can make it quiet with exhaust and slow the prop down.
 
One major thing that came out of the fwc airboat sound report was that propeller tip speed needed to be below mach .5 to be able to make noise less than 90 db .This propeller attempts to meet that criteria by being able to produce acceptable thrust at a low RPM with a low noise signature.And does pretty good I might add however it still loader than 90db at 50 ft wao.
 
Well, the other thing to consider is that the FWC's findings are based on the propellers that they had to test at the time ....... I'm still not convinced that a prop can't be designed or inexpensively modified that will have a lower sound signature at higher rpm's. Slowing one down isn't, in itself, a solution if it kills it's push.

That would save a lot of folks a lot of money if they did't have to go to a belt or gearbox (and sometimes a new cage) just to get quieter.

BF
 
At cruise speed and getting on a plane I'm below 90DB. My prop tips turn 137 MPH or a rotational velocity of 20.9 per sec to plane out. To cruise I run a 183MPH tip speed. The average speed of sound at sea level (changes due to altitude and humidity) is 708MPH so I'm far below mach .5. I think the main objective is to quite the boats while cruising and planning out. Not make them below 90DB at wide open throttle. Any way getting on a plane and cruising I'm below the 90DB.
 
Great thread guys I've been enjoying following it and I'm excited about the quiet competition or expedition. I know Cowboy met some guys at the Palm Beach show that are doing some pretty cool stuff with GPU's and gear boxes. I sure hope those guys make the trip to the expedition.

I wondered while I was reading this if anyone has contacted any main stream press that might be interested in covering the expedition and shining some light on just how much time airboaters like you guys spend trying to keep them quiet? Most do it to preserve the very right to airboat, but people opposed to airbaots solely due to noise pollution should be aware that no one works harder to minimize the impact of airboats than Airboaters themselves.
 
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