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Bow Thruster Question

R/C Submarine modelers

Bow Thruster Question

Postby Ramius-II » Sun Dec 09, 2012 2:25 pm

Hi All! :D
Some time ago I asked about using a bow thruster in a 1:100 scale Typhoon. The answers I got were that the bow thruster would be best in the stern and not the bow. So I just visited the Engler site and they now sell a bow thruster except it is designed to be in the bow and not the stern! Now I am totally confused and since I put my bow thruster in the stern I am wondering if I made a mistake? :?

Thanks, Ed
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Re: Bow Thruster Question

Postby Art Broder » Sun Dec 09, 2012 2:52 pm

My limited experience with a bow thruster was that it only was effective to change the heading when the sub was not moving forward. When the sub was underway, I saw little if any effect.
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Re: Bow Thruster Question

Postby Ramius-II » Sun Dec 09, 2012 2:59 pm

Thanks Art!
Was your bow thruster in the bow or the stern?

Best, Ed
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Re: Bow Thruster Question

Postby Art Broder » Mon Dec 10, 2012 12:19 am

Bow.
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Re: Bow Thruster Question

Postby Sub culture » Mon Dec 10, 2012 12:54 am

Bow thruster fitted to a 1/100th Engel boat.

'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Re: Bow Thruster Question

Postby Carcharadon » Mon Dec 10, 2012 7:44 am

If you just want to maneuver at low speed or stationary it doesn't matter if the bow thruster is in the front or back. A thruster in the front (bow) has less effect at turning the boat then a thruster in the rear (stern) as speed increases.

http://www.youtube.com/watch?v=IgeMuhRN ... hA&index=8

http://groups.yahoo.com/group/Jetnautilus/
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Re: Bow Thruster Question

Postby Sub culture » Mon Dec 10, 2012 12:07 pm

My thoughts are that a thruster, or a control surface are applying a force.

The difference is, that a control surface's force will increase with the boats speed, whereas a thruster will remain the same.

In a nutshell, to effect good control over a boat which moves much beyond a snails pace, you will need powerful thrusters, whether they're mounted forward or aft.
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Re: Bow Thruster Question

Postby Carcharadon » Mon Dec 10, 2012 12:28 pm

With all things being equal, thrusters in the rear provide a better turning radius at speed then thrusters in the bow. You may not believe me but that's okay. However I've put a lot of time and effort in developing the Jet Nautilus. And can speak from lots of experience. Versions one and two of the Jet Nautilus had turning thrusters in the front and after lots of experimentation version 3 was developed with thrusters placed in the rear to improve turning radius at full speed.

The latest video shows examples of turning radius.

http://home.comcast.net/~ryourk/2.wmv
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Re: Bow Thruster Question

Postby Sub culture » Mon Dec 10, 2012 3:44 pm

I think you're reading more into my post than I wrote. I didn't actually say anything about one location being preferential over the other, I said you will need powerful thrusters if you hope to turn a boat well when on the move at speed.

If a thruster is placed at the stern of a sub, it's likely to be much further away from the C.G than a forward based thruster, so it will exert a greater moment of force- leverage.
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Re: Bow Thruster Question

Postby Bob the Builder » Mon Dec 10, 2012 4:03 pm

All things being equal, I'd say it will depend on your use. I put thrusters in both my 1:100 Engel Typhoon and also in one of my big 66" Nautilus builds. There is some pretty good video of the Nautilus running here:

http://www.youtube.com/watch?v=i_vGTUlCQq0

Skip to 1:25 to bypass the OTW Dive Module overview.

No one is going to use a Graupner style thruster to steer at speed, let's be realistic. They're for maneuvering at low speeds or while docking. Both of my thrusters were bow-mounted, but that was more for practicality than anything else. There was simply more room up front that in the rear with all the linkages and drive shaft. I think that a rear thruster would make more sense, personally. That way if you're docking you can just point your boat at the dock (or pond side or what have you), ease in to a stop, and then thrust the stern in for a perfect docking. With the thruster in front, you'd have to reverse in for the same effect.

Solve the dilemma and just put two in! That would make for some pretty cool pirouettes underwater!

I think I remember that the real Typhoons actually had a drop down thruster pod. That would be a great thing to engineer for a scale boat. Just have it permanently dropped for simplicity if you wanted, tied to your rudder linkage for left/right steering. Have it power on when your rudder is hard over to either side.
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Re: Bow Thruster Question

Postby Scott T » Tue Dec 11, 2012 9:24 pm

Question to Carcharadon about his stern mounted thrusters. Where the thust discharge
mounted angled or perpendicular to the centerline of the boat?

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Re: Bow Thruster Question

Postby Carcharadon » Tue Dec 11, 2012 11:57 pm

Scott T wrote:Question to Carcharadon about his stern mounted thrusters. Where the thust discharge
mounted angled or perpendicular to the centerline of the boat?

Scott T



The nozzles for the turning thrusters are mounted perpendicular to the centerline and also aft of the main forward thrusters. In fact a turning thruster will interact (or divert) the stream from the forward thruster so that on one side of the boat two streams are affecting turning and this seems to enhance turning.
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Re: Bow Thruster Question

Postby Scott T » Wed Dec 12, 2012 2:38 pm

Thanks for the description and picture Carcharadon.
:wink:
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Re: Bow Thruster Question

Postby Timothy Guest » Wed Dec 12, 2012 8:25 pm

For the best results, put your bow thrusters as far aft as possible. As Sub Culture mentioned above, the greater the distance from the CG, the greater the moment arm, and the greater the effect. The same goes for rudders, ailerons, and elevators too.
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