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Have you measured your airboat thrust?

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Does anyone have a conversion chart for converting pucker factor to thrust values? :dontknow:
 
What numbers do you want it in?

I know of a Robicheaux boat that dragged about 320 pounds of weight hanging on the gunnel.

I know of an Alumitech that someone tied a tarp to the top sides of the cage, stood behind the boat and tried to hold the bottom corners with their hands as the driver hit the throttle. And there was money bet on it. The holder went airborne before he lost hold and his money.

I know of a Kline that dragged me at about 190 for about 20 yards. Nope, not mine, and how is another story.

I know of another Kline that flattened a 130 pound gal on the ground with its thrust. She dodged behind me to grab a hat as I hit the gas. oops

But have not been able to find a talbe to convert drag thrust pounds to push down thrust pounds or filling up the tarp pounds of thrust. Can anybody help.

:roll:
 
 
What gave you the slightest idea that he did not measure it to create the data. Read my first post. I asked for numbers.

Jim
 
At one point I believe powershift had some information on there site about obtaining a thrust goal. You could probably find out the information from them. I believe they did it with the boat on the trailer and a load cell in line. However, I would think you would have to be very careful to get a true reading due to fricitional loss.
 
jim":vrk6iyng said:
What gave you the slightest idea that he did not measure it to create the data. Read my first post.
Click to expand...

I'm not sure what you are talking about Jim. I thought you were asking for numbers - OUR numbers.

How do you measure thrust anyway?
 
Jim,

Got a friend that swears his boat will produce more thrust than anyone elses. A few years ago at a friends camp we were partaking of some liquid relaxation when he started again about his has more thrust than any other rig, while his boat was in yard behind his truck. We joked about it was to bad we couldn't tie bumper to bumper like we did with trucks as teenager and give it a test. While he went inside for more relaxation, we grabbed a drill, some scrap metal and a extension cord, ran up behind his boat and were drilling on the scrap metal when he came out. We answered his shocked cry, "What are you doing" with the answer, "Drilling holes in your boat to rig up eye bolts to do a transom to transom pull test." :shock: Even after he realized we were joking, he still was mad. Never figured that one out.

Don't know why he will not stop by with the boat behind his truck anymore. :roll:

Now that is the test we need to figure out how to do. :wink:
 
Good one Marshmaster.
Jim, My Dad told me that he went to an airboat show once, and Terminator Props was putting on a thrust test for free.
I believe the guy's name was Wagaman, Tim or Tom. He was in the engineering section of Terminator.

He had a thrust indication device that he had built, that he would insert between the airboat trailers tounge, and the tow vehicles hitch.

He would then have the boat under test wind it up, while he obtained the direct thrust measurement for the as found prop / engine combinations.

Then he would mount one of his composite props, and measure the max thrust again. He also had a conversion formula to derive a hosepower reading from the measured thrust.

Then the dude would print you out his measurement data for both the baseline prop, and his Terminator and give it to each participant.

My Dad said seeing the dfference in those props performance, demonstrated in hard numbers like that was a mind blower. He had a hard time letting that guy pull that shiny thrust generator back off of his crank flange!

Soon as he could, he went out and got a composite two blade.

Oh-yeah, It was a Terminator.

Sorry for taking so long.

Long story short, thats the only time I've heard of some one developing a meathod to measure the thrust from a variety if different boats safely, and accurately.

Perhaps he could come to one of our runs, and demo his props to interested parties. We could get Basket to measure the sound level while the boats are under test.

Quietest boat / Highest Thrust contest?
 
Jim,

Would be cool to see many more different combos and respective numbers!

Cowboy,

You know that I still think Cntry has some really quiet squirrels on steroids hidden in his boat!

"Cadillac" sound meter on ready to go status!

Basketcase
 
bps that would be neat to have that device at one of our runs so we could all see what we got and have a contest Whose Got The Most Thrust I will buy a S.A. tshirt for a prize if you get a chance ask him if we could do this one day. I just need to make another run (priorities)
 
I'm sure the twin turbo 572 that Felber built with the 8 blade counter rotating Power Shift prop will rule in the max thrust arena. I CAN ASSURE YOU ONE THING YOU WILL NEVER SEE ME STANDING NEXT TO A BOAT THAT THE MAX THRUST IS BEING TESTED. Most airboat engine stands are borderline when the boat can move but when you pin it down and prevent the boat from moving you have quadrupled the stresses and forces exerted on the engine stand. Besides that I’m more worried about how the entire boat performs. Max thrust numbers are like dyno numbers or flow bench numbers they mean very little compared to the rest of the picture. I could care less about max thrust numbers. I’m more concerned about snap and broadness, (after all, how long or often does somebody run their boat wide open) Even when running dry most people don’t run more than 50% or 60% of max throttle.
 
Hey Mood Guess one of the things my wife got me for Christmas. A hint you have one on your boat. I hate weighing down my boat with accessories but in this case it's a must. HE-HE-HE. I have one important use planed for it.
 
My comments (so far)

It seemed like a simple question.

It is done all the time to airplanes, some with thousands of pounds of thrust.

Airplanes are designed to withstand the loads of static full power runs and it is done all the time. (every carrier launch for example)

This one was designed in the 40's and will take it.
AmphibianD_WEB.jpg


An engine stand that cannot withstand a full power static run is unsafe in my opinion. That should be a design criteria considering the ramifications of a failure.

I have seen threads get off track before, but this one got off track with the first post and stayed there. That has to be a record.

jim
 
Jim I think most people just don't have the resources to adequately answer your thrust question. I for one haven't a clue on how to measure thrust on my boat.
 
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