Seaview Powerplant

[junglelord]

Hi gang.
I wanted to know Mr Merriman if you could tell me what the top speed of the Seaview conversion kit with 2 280 speed motors is approximately.

I saw a converted kit that was not a Merriman build that used a 550 motor and a pumpjet system. It seemed to have significant power.

I wondered how the two different applications of power were adapted to a model of that weight and size.

Since no one is making any other conversions, I was looking at a modified attempt on one of my order models. The idea of a 550 pumpjet was pretty cool.

[He Who Shall Not Be Named]

Hi gang.
I wanted to know Mr Merriman if you could tell me what the top speed of the Seaview conversion kit with 2 280 speed motors is approximately.

I saw a converted kit that was not a Merriman build that used a 550 motor and a pumpjet system. It seemed to have significant power.

I wondered how the two different applications of power were adapted to a model of that weight and size.

Since no one is making any other conversions, I was looking at a modified attempt on one of my order models. The idea of a 550 pumpjet was pretty cool.

Maximum speed observed on the SEAVIEW (the stock Moebius kit with stock SD) is in submerged trim, three hull diameters deep. I would guesstimate it at around 3-5 MPH.

David,

[junglelord]

WAY TO GO MR MERRIMAN.
I'll drink to THAT!
That is more then enough.....
I am not going for a 550 then.
Thanks, your the man.

Now can I only make cuts in the lower section of the nicelles to advoid lack of scale apperance...will this be enough flow for the pumpjets? Naturally I would increase the square area of the lower openings to makeup for not making one on the top....any ideas?

[toppack]

I remember an air flow dynamics test we did that showed that the Intake should be about twice the area of the Exhaust. I realize that's not always possible but for maximum efficency, that's best. That's a ducted-fan air duct and I suppose water would be similar.

[He Who Shall Not Be Named]

WAY TO GO MR MERRIMAN.
I'll drink to THAT!
That is more then enough.....
I am not going for a 550 then.
Thanks, your the man.

Now can I only make cuts in the lower section of the nicelles to advoid lack of scale apperance...will this be enough flow for the pumpjets? Naturally I would increase the square area of the lower openings to makeup for not making one on the top....any ideas?

You could do that, but how about opening up the lower portions to the size I recommend and also open up the mini-sub hatch? You'll get about the same intake area, but your backing performance will suffer (and the boat will pitch down when you back down).

David,

[He Who Shall Not Be Named]

I remember an air flow dynamics test we did that showed that the Intake should be about twice the area of the Exhaust. I realize that's not always possible but for maximum efficency, that's best. That's a ducted-fan air duct and I suppose water would be similar.

That's the rule-of-thumb I subscribe too.

David,

[junglelord]

You could do that, but how about opening up the lower portions to the size I recommend and also open up the mini-sub hatch? You'll get about the same intake area, but your backing performance will suffer (and the boat will pitch down when you back down).

David,

I would not want to run with the subbay hatch open.
I would rather add some additional keel openings about here



Do you know how well this would work with your system Mr Merriman?
Trying to keep it scale to visual apperance to the observer, I would rather stay with keel vents in the hull and the nicelles. I wonder how well the nicelles would do with just this keel hull vent. I could make this vent first then open the nicelles in the lower portion if this is not sufficent. What do you think Mr. Merriman? This hull keel vent would be insufficent for the powerplant you have for us, correct Mr. Merriman? I think so just as a guess, what is your best educated guess kind sir? I could try it this way first then cut the lower nicelle later if its ineffective, correct?

[He Who Shall Not Be Named]

I would not want to run with the subbay hatch open.
I would rather add some additional keel openings about here

Will you please think things through! ...

... If you examine the carefully edited video of the SEAVIEW using that scheme, you'll note that the boat will run fine underwater at a given speed and plane set-up. However, when there's a need to back down to avoid a depth excursion (the boat, so configured, is on the razor's edge of pitching down when running submerged), the boat violently increases the pitch-down maneuver as a sizable quantity of the backing water is vectored vertically DOWN. This pump-jet scheme turns the intake into a 'thruster' that does just one thing: pitch the nose down.

You People!

David,

[toppack]

Hey, you could always let it Roll inverted when underwater, then it would Shoot up out of the water like a Dolphin. :D LOL :D
Great Fun, don't ya think! :D

[junglelord]

I am not going with anything but your conversion.
I had considered and asked the other guy about his and decided that I will just make two of yours. However I am considering some slight variables as you well know. I have asked about bow planes vs just fixed vanes. I am also wondering about just keel vents vs vents that are visable to the observer. If the subbay doors open is an option (one I do not want to do) then hopefully with this rule applied

I remember an air flow dynamics test we did that showed that the Intake should be about twice the area of the Exhaust. I realize that's not always possible but for maximum efficency, that's best. That's a ducted-fan air duct and I suppose water would be similar.

I can obtain equal results with just lower nicelle vents
I'll drink to THAT!

[junglelord]

Will you please think things through! ...

... If you examine the carefully edited video of the SEAVIEW using that scheme, you'll note that the boat will run fine underwater at a given speed and plane set-up. However, when there's a need to back down to avoid a depth excursion (the boat, so configured, is on the razor's edge of pitching down when running submerged), the boat violently increases the pitch-down maneuver as a sizable quantity of the backing water is vectored vertically DOWN. This pump-jet scheme turns the intake into a 'thruster' that does just one thing: pitch the nose down.

You People!

David,

I appreciate I am asking all these from the master and you did EVERYTHING you did for a REASON from being the Master.

I know I am grasshopper...I am not trying to snatch the pebble, and maybe I should just realized that my above sentence is the thing I need to consider instead of my wondering options.

Thanks for being so kind.
I should have the first model here this week and I will have the other one by next weekend. I can make my first D&E Sub-driver LPB system this March or April at the latest...but I will be good to go.

Again thanks a lot for answering all my questions.
Cheers
Dean

[He Who Shall Not Be Named]

I appreciate I am asking all these from the master and you did EVERYTHING you did for a REASON from being the Master.

I know I am grasshopper...I am not trying to snatch the pebble, and maybe I should just realized that my above sentence is the thing I need to consider instead of my wondering options.

Thanks for being so kind.
I should have the first model here this week and I will have the other one by next weekend. I can make my first D&E Sub-driver LPB system this March or April at the latest...but I will be good to go.

Again thanks a lot for answering all my questions.
Cheers
Dean

Hey, you don't keep questioning (within reason) you won't understand. Keep snatching at that pebble. And I'll keep smacking your knuckles when you miss.

David,

[junglelord]

I tell you Mr Merriman, between the voodo doll and the rapped knuckles, I think I will just do what you tell me too.
Crack That WHip

My favorite video on Youtube.
Almost at 2000 hits.
I must have watched it and shown it 20 times myself.
I'll drink to THAT!

When you mention blood pressure blower not working, you mean the LPB?
May I ask why it was not working?

If I got it right, the Snort system was not in operation that day.
If that is correct, then it would be even more responsive to dive and surface then what occurs on video?
Ie it was more dynamic dive in that mode? Or it was just not possible to sift back and forth between ballast and snort?

[He Who Shall Not Be Named]

I tell you Mr Merriman, between the voodo doll and the rapped knuckles, I think I will just do what you tell me too.
Crack That WHip

My favorite video on Youtube.
Almost at 2000 hits.
I must have watched it and shown it 20 times myself.
I'll drink to THAT!

When you mention blood pressure blower not working, you mean the LPB?
May I ask why it was not working?

If I got it right, the Snort system was not in operation that day.
If that is correct, then it would be even more responsive to dive and surface then what occurs on video?
Ie it was more dynamic dive in that mode? Or it was just not possible to sift back and forth between ballast and snort?

It was an intermittent problem -- actually, once in the water the low pressure blower (LPB) switch started working again (a programming problem with a Chinese supplied switch initially installed). Operation of the ballast sub-system -- either the gas or LPB -- has no effect on the dynamics of the boat in motion. That ballast tank is either used fully flooded or completely empty. If and when the LPB was not working I simply used the gas side of the sub-system to empty the tank when I wanted to get back to surfaced trim.

David,

[junglelord]

If I get it right, the snort is only a surface, periscope trim, device.

In the video you have a still slightly positive trim with ballast and have a very slight need for forward momentum to dive. Hence the slight dynamic dive. The ballast system plus the way the model is set for boyance, is the key to static dive, with a slightly negitive trim, pre ballast, correct?

I love your system and now I am more then hungry to make it EXACTLY like you have it...sorry for being so inquisitve with needless lack of confidence. If you can do it, I can do it....

The upper nicelle openings would limit bow pitch with reverse thurst, correct?