Testing new stingernental boat

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flying fish
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Re: Testing new stingernental boat

Postby flying fish » Sat Jan 02, 2010 8:51 pm

24d wrote:So now we have a car motor turning 6,000 RPM making 350 HP going thu a gear box turning a prop 2,000 RPM then when you back the prop down to 1,000 RPM your motor is turning 3,000, you just lost at least twice but more than likely three times the HP the aircraft engine did doing the thing.

I'm not putting down a car motor but thats the basic math of it.


24d

A given--- Descent prop on both engines.

carmotor probably makes 350 horse @5252 and makes 350 torque @5252 and each # at the flywheel. Using a 3 to 1 redrive, we then have 1050 # torque at the output shaft on auto engine's redrive @5252 rpm.

In your basic math of it scenario's, how much thrust is lost in each scenario using torque to spin each propellor, and then decreasing each prop's rpm by say 1/2 ??
Torque spins each prop. Right?
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Re: Testing new stingernental boat

Postby dantheairboatman » Sat Jan 02, 2010 9:14 pm

Hmgm123. Depending on the engine the adapter kit with stinger will run you 4000 to 4300$ our box is set up differant for the ac so you will have to have it changed if you own one already. After running my boat it well worth it. Now if you want more power or want to go to a bigger boat you don't have to raise compresion or go car motor and you can do it all with half the sound. It was odd with the reduction the engine did't sound like it was straining at all. Even at 3000rpm it was purring. But if I know me I will have 10:1 pistons and nos on it before to long :D
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Re: Testing new stingernental boat

Postby goldhunter_2 » Sat Jan 02, 2010 9:21 pm

well dan if your going to start planing upgrading already just plan on some 520 stuff :lol:
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Re: Testing new stingernental boat

Postby hmgm123 » Sat Jan 02, 2010 9:31 pm

dantheairboatman wrote:Hmgm123. Depending on the engine the adapter kit with stinger will run you 4000 to 4300$ our box is set up differant for the ac so you will have to have it changed if you own one already. After running my boat it well worth it. Now if you want more power or want to go to a bigger boat you don't have to raise compresion or go car motor and you can do it all with half the sound. It was odd with the reduction the engine did't sound like it was straining at all. Even at 3000rpm it was purring. But if I know me I will have 10:1 pistons and nos on it before to long :D

OK, ya you are right that thing purrs like a kitten!!!

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Re: Testing new stingernental boat

Postby dantheairboatman » Sat Jan 02, 2010 9:34 pm

Yeah but the 470 520 550 all have the same head valve and intake. I'm thinking a nasty cam little valve job with some liter after maket pistons and ristpins. Maybe some nice rockers if they make them. Let the gear do the work and let the liter moter stretch it's legs? Maybe hard to argue with ci though. Just my speculation. My engine gearbox all eceseries with oil is 526pd on garretts postall certafies load cell
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Re: Testing new stingernental boat

Postby goldhunter_2 » Sat Jan 02, 2010 9:39 pm

526 ain't bad if you compare to one of your old car motors with the gearbox and accessories
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Re: Testing new stingernental boat

Postby hmgm123 » Sat Jan 02, 2010 10:34 pm

That just a little lighter than a SC0540

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Re: Testing new stingernental boat

Postby 24d » Sat Jan 02, 2010 10:36 pm

flying fish wrote:
24d wrote:So now we have a car motor turning 6,000 RPM making 350 HP going thu a gear box turning a prop 2,000 RPM then when you back the prop down to 1,000 RPM your motor is turning 3,000, you just lost at least twice but more than likely three times the HP the aircraft engine did doing the thing.

I'm not putting down a car motor but thats the basic math of it.


24d

A given--- Descent prop on both engines.

carmotor probably makes 350 horse @5252 and makes 350 torque @5252 and each # at the flywheel. Using a 3 to 1 redrive, we then have 1050 # torque at the output shaft on auto engine's redrive @5252 rpm.

In your basic math of it scenario's, how much thrust is lost in each scenario using torque to spin each propellor, and then decreasing each prop's rpm by say 1/2 ??
Torque spins each prop. Right?
You would need to know the torque the c/m had @ 2626 and the torque of the a/m @ 1500 + take into account the c/m is 1126 rpm farther away from ve than the a/m, but the comment was 300 hp at the prop hub not the fly wheel.

airduds wrote:Sorry but that's bs. 300 hp at the prop hub is 300 hp - regardless of what's in front of the prop hub.
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Re: Testing new stingernental boat

Postby 24d » Sat Jan 02, 2010 11:18 pm

dantheairboatman wrote:Hmgm123. Depending on the engine the adapter kit with stinger will run you 4000 to 4300$ our box is set up differant for the ac so you will have to have it changed if you own one already. After running my boat it well worth it. Now if you want more power or want to go to a bigger boat you don't have to raise compresion or go car motor and you can do it all with half the sound. It was odd with the reduction the engine did't sound like it was straining at all. Even at 3000rpm it was purring. But if I know me I will have 10:1 pistons and nos on it before to long :D

Can you put a % of increase of thrust @ 2,000 engine RPM and then another @ WOT someone could get by just adding the multiplier?

Thanks,
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Re: Testing new stingernental boat

Postby flying fish » Sat Jan 02, 2010 11:34 pm

24d wrote:
flying fish wrote:
24d wrote:So now we have a car motor turning 6,000 RPM making 350 HP going thu a gear box turning a prop 2,000 RPM then when you back the prop down to 1,000 RPM your motor is turning 3,000, you just lost at least twice but more than likely three times the HP the aircraft engine did doing the thing.

I'm not putting down a car motor but thats the basic math of it.


24d

A given--- Descent prop on both engines.

carmotor probably makes 350 horse @5252 and makes 350 torque @5252 and each # at the flywheel. Using a 3 to 1 redrive, we then have 1050 # torque at the output shaft on auto engine's redrive @5252 rpm.

In your basic math of it scenario's, how much thrust is lost in each scenario using torque to spin each propellor, and then decreasing each prop's rpm by say 1/2 ??
Torque spins each prop. Right?
You would need to know the torque the c/m had @ 2626 and the torque of the a/m @ 1500 + take into account the c/m is 1126 rpm farther away from ve than the a/m, but the comment was 300 hp at the prop hub not the fly wheel.

airduds wrote:Sorry but that's bs. 300 hp at the prop hub is 300 hp - regardless of what's in front of the prop hub.


24d
adding the torque multiplier to the automobile engine, one has to consider torque at he prop hub also. could it be possible that both engines loose the same % of torque at the prop hub by decreasing prop rpm by 1/2?
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Re: Testing new stingernental boat

Postby cntry141iq » Sat Jan 02, 2010 11:42 pm

Man this ought to get good before it is over LOL

you don't increase HP with a gear box .. you increase TQ. Hp is only a calculation as was stated. The old saying used to be that TQ gets you going HP keeps you going. A prop needs TQ not hp. You have to have to think different to benefit from turning a prop slower ... The thrust is still there but the sound usually drops way down due to tip speed. Of course more pitch or more blades are required to harness the TQ effectively.
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Re: Testing new stingernental boat

Postby dantheairboatman » Sat Jan 02, 2010 11:50 pm

Still gathering data at this point. The gearbox is a torque multiplyer. It also alows a engine to get into it wndow of power and aply that eficiatly to the prop. Bigger prop grabs more air or generates more lift. At a lower prop speed. A 72in prop is not eficiantly producing thrust beyond 2950 so you are leaving a little on the table and loud . Don't think I answered your question just a couple of thoughts.
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Re: Testing new stingernental boat

Postby 24d » Sat Jan 02, 2010 11:52 pm

flying fish wrote:l24d
adding the torque multiplier to the automobile engine, one has to consider torque at he prop hub also. could it be possible that both engines loose the same % of torque at the prop hub by decreasing prop rpm by 1/2?


Yes it is possible but I would doubt it because the c/m would be so much father away from ve than the a/m. I'm sure someone has a chart that would answer that question. I looked around a little but lost interest. I don't like the fact that I'v had a hand in derailing this thread into another c/m vs a/m thread, it's frustrating when you use the search feature to get information and every tread turns into this. :oops:
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Re: Testing new stingernental boat

Postby flying fish » Sat Jan 02, 2010 11:58 pm

Sorry Dan for getting off track on you guys work of art.

No disrespect meant towards you 24d.- Just a torque thing got me to thinking a bit outside the box i Guess.
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Re: Testing new stingernental boat

Postby swampdragster » Sun Jan 03, 2010 9:15 pm

I SAW DAN'S BOAT RUN AT LOCH LOOSA THIS WEEKEND,VERY NICE....IT WAS THE QUITEST BOAT OUT THERE AND RAN THE HILL WITH EASE...
KEEP UP THE GOOD WORK DAN.....
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Re: Testing new stingernental boat

Postby hogdoggin » Sun Jan 03, 2010 9:45 pm

Dan any luck with the gear box for a 0360 yet?

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Re: Testing new stingernental boat

Postby dantheairboatman » Sun Jan 03, 2010 10:14 pm

I hope we can get it worked out . That would be a great combo!
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Re: Testing new stingernental boat

Postby C1gator » Sun Jan 03, 2010 10:26 pm

Dan, very nice and innovative.....Keep up the good work man.....You might have posted this already, but what is the tip speed on the blades at WOT? Thanks....

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Re: Testing new stingernental boat

Postby dantheairboatman » Sun Jan 03, 2010 10:52 pm

1847 right now. After the injection goes on I will bring it up some. That is a 3bl 82 r
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Re: Testing new stingernental boat

Postby 24d » Mon Jan 04, 2010 1:48 am

Question on gear drive. If you take into consideration the prop is a gear, the gear box down shifts the prop then by increasing pitch, you are in effect, gearing back up. In the end, have you geared up or down? It's been stated over and over you are in effect "geared higher" at idle as well as other RPMs (the boat moves faster @ the same RPM). Are we gearing up or gearing down? It's just hard to wrap my brain around it. If we are gearing up then just turning the prop faster was taking alot of energy that we would now be using to move air, it does take alot of energy to spin a XXXlb object 1.5 to 3 times faster.
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Re: Testing new stingernental boat

Postby Blowhard » Mon Jan 04, 2010 8:19 am

(Cliff Clavin mode on)

Here's a simple way to visualize torque: Imagine holding a 1-pound weight straight out, with your arm parallel to the ground. My arm measures about two feet from shoulder to wrist. If I hold a 1-pound weight straight out, the torque my shoulder experiences is roughly 2 foot-pounds (2 feet times 1 pound). If I were to hold a 10 pound weight in my hand, then the torque on my shoulder would be roughly 20 foot-pounds (2 feet times 10 pounds).

Now think of this turning force applied to a wheel, such as if a lever was attached to the center of an automobile wheel. The more force you apply on that lever, the more torque you apply to the wheel, the more readily the wheel turns, and the faster the car starts moving. See where I’m going with this? Torque is a measure of the ability of an engine to do work. It's a component of, but not the same as, the (horse) power of the engine, which is the rate at which work can be done. In an automotive engine, power and torque are related by a simple equation that considers torque, engine speed (in revolutions per minute), and a conversion factor.

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Re: Testing new stingernental boat

Postby JOLLY ROGER » Mon Jan 04, 2010 8:34 am

24d wrote:Question on gear drive. If you take into consideration the prop is a gear, the gear box down shifts the prop then by increasing pitch, you are in effect, gearing back up. In the end, have you geared up or down? It's been stated over and over you are in effect "geared higher" at idle as well as other RPMs (the boat moves faster @ the same RPM). Are we gearing up or gearing down? It's just hard to wrap my brain around it. If we are gearing up then just turning the prop faster was taking alot of energy that we would now be using to move air, it does take alot of energy to spin a XXXlb object 1.5 to 3 times faster.


An easy way to visualize this Larry is to think of the prop as a screw or bolt. More pitch is a course thread and less pitch is a fine thread.
The course thread will move farther per revolution , but requires more torque to move it.
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Re: Testing new stingernental boat

Postby BigJakesrq » Mon Jan 04, 2010 8:53 am

24d wrote:Question on gear drive. If you take into consideration the prop is a gear, the gear box down shifts the prop then by increasing pitch, you are in effect, gearing back up. In the end, have you geared up or down? It's been stated over and over you are in effect "geared higher" at idle as well as other RPMs (the boat moves faster @ the same RPM). Are we gearing up or gearing down? It's just hard to wrap my brain around it. If we are gearing up then just turning the prop faster was taking alot of energy that we would now be using to move air, it does take alot of energy to spin a XXXlb object 1.5 to 3 times faster.



With a gear reduction you're spinning the prop SLOWER and the engine Faster. ie 1 to 1.xx+(common1.73) or 1 to 2.xx+(common2.68) That is the simplest way I can think of to describe it.

In super simple terms. The engine is making more power at higher RPM's and with the gear reduction you can spin a prop that was designed to make more power down lower in the rpm range. Those props are so big, you have to have the gear reduction to be able to spin them, in most cases though.

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Re: Testing new stingernental boat

Postby dantheairboatman » Mon Jan 04, 2010 11:25 am

c1gator you have to allow about 18 to 20in from the deck . it will stop about 6in from it but does not need to comprese near that much when it's operating. i will not go back after having this unless it was a race boat!
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Re: Testing new stingernental boat

Postby goldhunter_2 » Mon Jan 04, 2010 11:41 am

see I know we could convert you to a aircraft guy :lol:
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