Jump to content

Electric Fan Drive?


Recommended Posts

Pretty content-free. It's not clear that it's got any efficiency or power advantages. I also predict sealing issues. That's a big circumference and high linear speed for a rotary seal. A possibly worse mousetrap until proven otherwise. 

On the other hand, CARBON! Doesn't it look cool??? Take my money!!!

  • Like 2
Link to post
Share on other sites

The big advantage of rim drive is supposed to be that it is largely foul proof. I've seen videos of them sucking in and spitting out a tarp, fishing nets, etc. I could see designs that do not use a seal (perm magnets in the rotor, flooded bearings). This company is fairly cagey on the price. They are one of the very few electric companies honest about the horsepower: 6KW input, 8hp claimed, which is about right. Most electric companies claim about 3 times the hp that is physically possible. 

Link to post
Share on other sites

6kw is a big motor for a dinghy and is going to need a huge and heavy battery.  Doesn’t look practical as the auxiliary on a small sailboat where that motor power makes a lot of sense. 

Link to post
Share on other sites

Possibly, but their video and their website are both very thin on technical details. Promoting your technology as a breakthrough without saying why or how is always a red flag to me. 

  • Like 1
Link to post
Share on other sites
7 minutes ago, DDW said:

The big advantage of rim drive is supposed to be that it is largely foul proof. I've seen videos of them sucking in and spitting out a tarp, fishing nets, etc. I could see designs that do not use a seal (perm magnets in the rotor, flooded bearings). This company is fairly cagey on the price. They are one of the very few electric companies honest about the horsepower: 6KW input, 8hp claimed, which is about right. Most electric companies claim about 3 times the hp that is physically possible. 

Possibly, but their video and their website are both very thin on technical details. Promoting your technology as a breakthrough without saying why or how is always a red flag to me. 

Link to post
Share on other sites

I saw this at first and thought someone took a Dyson fan, turned it upside down and stuck it in the water. This is very similar to a ducted fan design which inherently is inefficient by about 50% compared to a prop designed system I suppose that if it's double the RPM's then it' levels out however the current will also be double. Compared to the bulb of Torqueedo motor house to that of the "duct" housing I wonder which has more drag.  

Link to post
Share on other sites

I want to see what it does at two in the morning going over a reef....

Kort nozzles have been around awhile not sure if there is any big efficiency gain in this. If it is a big sealed rotor running with permanent mag the concept is interesting. Doesn't look like it will take any abuse, pretty sure a bull kelp could kill it.

Link to post
Share on other sites

That is a hideous shape for a Kort Nozzle. In cross section they should be an airfoil. That is not. It is fat and chunky at the trailing edge.

Proper nozzle shape:

figure3.jpg

 

Rim drive bow thrusters have been around for a while too. The self adjusting blade part is new however.

Link to post
Share on other sites
2 hours ago, SASSAFRASS said:

Wonder how they are setting the pitch, if it's a rpm or friction torque set or mechanical. A mini bollard pull with a Dyno in the video would be nice.

The adjustable ones in the vid look to me like they work similarly to autoprops.

Link to post
Share on other sites
On 10/7/2020 at 5:10 PM, IStream said:

It's not clear that it's got any efficiency or power advantages. I also predict sealing issues.

Recently been looking, trying, into a company that builds similar rim electric drives in Germany.
Their english website is even worse though. http://www.fmt-kempen.de/en/products.htm

To adress your keypoints, they state 80+ efficiency, about same as the torqeedo and spirit, and the whole unit is maintenance free with the electrics fully potted and bearings water lubed ceramic rollers.

Personally I like that they sell it as a retractable system. Where the whole unit just gets pulled up into a sealed shaft, some 300mm diameter or so and not much higher(at most, some units are significantly smaller), and leaves the bottom clean like with some thrusters. That is such a nice feature to have and seems fuss free due to the simplicity of the system. Compact too so you can fit it into smaller boats more easily.

And they offer regeneration. Which I am sure is draggy, but if you're in need I bet this is quite nice to have.

An installation example Click on the pictures to scroll through. The website is kind of bad but some very good pictures of the shaft and how it retracts.: http://www.fmt-kempen.de/l30.html
 

Hefty pricetag though at 3000-6000Euro for 2-11kW (see flyer below, bottom row)

http://www.fmt-kempen.de/media/files/Flyer_Datenblatt_MOMENTUM_M90_DINA4_r0_deutsch.pdf

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...