Twin Jet testing?

[GunninGopher]

I remember reading a few months back in Hot Boat about someone developing/testing a twin jet setup, that ran off of one motor. I haven't seen any updates on that yet, and can't find a post here about it. Does anyone know what I am referring to and have some info?

[corky]

Harold Bruce of R/D marine in Anahiem is developing this jet.

[flat broke]

corky:
Harold Bruce of R/D marine in Anahiem is developing this jet.I guess that really depends on who you ask and possibly what the courts decide.
Either way, an update would be cool. We haven't heard much excep the little bit of info Dave gave us in one of the other threads.
Chris

[HM]

My guess is you won't hear about R&D's final in Hot Boat regardless of what the court says.
Aggressor is the other company doing work on this twin jet application(s) and on the other side of the court battle.
I saw Bruce's (R&D) prototype at the OC Boat Show - it looked cool. Rumor has it that the motor was not set up well (low HP, poor tuning) but still gave some promising results - meaning it actually worked.
I would like to see the jets counter rotating, but the prototype (Bruce's) had both jets turning the same way - but what do I know - I am just a prop guy!
[ August 19, 2002, 10:15 AM: Message edited by: HolyMoly ]

[flat broke]

HolyMoly:
I would like to see the jets counter rotating, but the prototype (Bruce's) had both jets turning the same way - but what do I know - I am just a prop guy!Frank,
If the manufacturer does a good job of axial flow control in the bowl and getting the thrust out straight, the like/counter rotating issue should be close to moot. You have to look at it from an equipment manufacturer's perspective. They would have to re-tool new molds for the bowls, and impellers if they had counter rotating setups. It's waaaaay cheaper/faster to bolt two like pumps onto that intake. Either way, it will be interesting to see if there is every a noticible gain out of the whole deal. Idealy they need two identical hulls with identical dyno proven motors. One setup gets a single pump, the other gets the twin. So far we have heard of test beds, but they weren't comparable to other test beds, so the results really have nothing to correlate to. If EITHER of these companies wants a professionaly written test plan and concise test methodology statement, I'd be more than happy to take on some contract work. Unfortunately, I don't think the $$ is there to do the type of testing that a product like this would require.
Chris

[GunninGopher]

What are the goals with this. Isn't it just more top end efficiency?
Interesting to hear about the lawsuits, I hope that doesn't put a damper on any possible development.
Is there any information elsewhere on this, or are people pretty tight lipped?

[Kwicherbichen]

GunninGopher:
What are the goals with this. Isn't it just more top end efficiency?
Interesting to hear about the lawsuits, I hope that doesn't put a damper on any possible development.
Is there any information elsewhere on this, or are people pretty tight lipped?The goals, as I understand them after talking to both developers, are for use on large boats. There will be specialty applications. I heard there may be a drag boat project in the midwest or back east that may feature an 21' Edge Phantom with Aggressor Dual Drives.
I wouldn't expect great top end leaps right away. I took a ride in the 21' Ultra that Harold Bruce has set up with dual drives. It definately gets out of the hole and planes fast but I don't think it really does much over 55 mph. I could be wrong about the top end though? It's also pretty cool to look back and see two roosters!
I'm not sure there will be any lawsuits? It seemed kinda heated at first when the developers were divided on issues but now things seemed to have calmed down. So now you have two companies producing similar units. Aggressor Jet Drives makes a unit and R&D Marine produces the other unit. Basically they are the same. They use the same intake but the gear boxes are made by different companies. R&D uses one made by a partner and Aggressor uses one made by Casale of V-drive gear box fame. Both are 1 to 1 ratio. R&D says their unit is a stand alone piece and you choose your bowls and associated pieces. Aggressor will be able to do the same thing but I would just buy the whole set up from them (bowls, impellers, divertors, etc...) to keep things simple.
I would think we'll see more by next season. After all, these duals basically came together at the begining of the summer.

[HM]

Chris,
you guys are always teaching and old prop a new trick. I still like the counter rotating idea - it is the engineer in me that won't let that go. I know it is much cheaper to only have to produce one set of jet and hardware - but you saw my boat - cheap is something I have yet to learn!
As far as a written test plan, a great scientific and statistical approach to R&D is Six Sigma - are you familiar with this? Six Sigma was championed by Xerox and Motorola and has found its way into Lockhead, Boeing, and other aerospace companies along with a ton of other companies.