Ok, thank you! I like the idea, it will provide perfect cooling for the motor and gearbox.
Did you change the grease in the gearbox with high speed lubricant? Does it come with any grease at all?
Yes, cooling is good this way!
Reisenauer strongly advised to use their grease instead of e.g. Makita grease. Just bought 5ml for 5eur from them, didn’t want to take the risk and there’s a lot of technology in greases.
The grease around my shaft and seals is just for keeping the water out, therefore I use cheap marine grease.
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@Thijs I have another question 
You posted pictures of your ESC settings above, did you stay with the extra hard braking? It may be best for the gearbox to turn braking off or to extra soft, so that the gears can keep flowing on the grease and don’t forcefully hit metal. It should also draw less power.
Hi Benjo, I wanted to enable hard braking because of safety. But it turned out that I cannot enable this option on my ESC.
I sticked to the other options, except that I reduced the motor timing to 3°
I wanted the put the seal around the gearbox shaft , not around the propeller shaft , to make it shorter
Yesterdaymorning I was able to make my first flight; it was amazing and not so difficult! @pacificmeister , do you also have the impression that the wing angle could be slightly better? I’m curious about your opinion
Unfortunately my motor broke down in the afternoon already. Honestly I saw it was drawing already 5000+w with not even full throttle, but I was to tempted to go for it anyway.
Afterwards I realised I have programmed my ESC motor timing to 3° which was more of a wild guess. and this is probably wrong?
As my old AquaStar 4084 620KV was originally designed for 10s, so I want to switch to the following setup:
Typhoon HET 700-98-670 brushless, @jakebarnhill1 and @Mat , I saw you were talking about motor timing degrees. Do you have any idea what would be the safest timing for such a motor? I can also select PWM, any idea what this means and how many kHz?
Custom 7 7/8 x 7.5 honda 5hp prop
https://www.aliexpress.com/snapshot/0.html?spm=a2g0s.9042647.0.0.53374c4dMoI980&orderId=94220174299377&productId=32691369808
But then lathed down to 136mm, the same as @PowerGlider in this topic:
Based on the calculation below(rough estimation), 1.1hp(800w) would give me a speed of around 14kn (25kmh). Probably the real figure is worse, I dont see a value for slip etc.
Hope you have some thoughts on this approach 
btw, I will switch back to a configuration where my motor is inside the tube. The motor was not strong build(thin aluminium and tiny screws), the body was not really able to transfer the power.
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I haven’t had experience with in runners yet, but you need lower timing for in runners from what I’ve read. I think your guess of 3 degrees wasn’t a bad guess. put it in water and give it lots of throttle, if it loses sync i.e. the motor stops or squeals to a halt, increase the timing until it doesn’t lose sync.
awesome work on the build!
The PWM rate is the rate at which the Fet switching is done I think an ESC guru could chime in here I don’t fully understand it.
from what I understand however a higher PWM rate is good for low inductance motors (usually smaller motors) so they run smoothly, with a high PWM rate the esc will run a little warmer due to more switching losses. With my outrunners 8KHZ works fine, at the current moment I’m running 10KHZ I couldn’t notice a difference.
maybe @PowerGlider @nickw1881 @Flo could chime in here and explain how it works more!
Hi fellow builders,
Hereby a little update:
I bought 2 other props; 7 7/8 x 7.5 honda 5hp prop
One lathed down to ±140mm
I still have the 7.25x5, I just lathed the hole to 12mm to fit on my new shaft.
I will still use my reisenauer 6:1
I will use my new Typhoon HET 700-98-670
Saturday I will test the 3 different props with different motortiming and measure the thrust and amperage. Hopefully make another run when everything looks safe
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btw, the motors could be bought rediculour cheap at http://www.rc-warbirds.com/product_info.php/products_id/1131
only 80dollar
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Hi Thijs 
When reading about your motor specs, the shaft seems to be 8mm
But then you have a 6:1 Reisenauer…
So I guess you lathed down the motor shaft to 5 mm ?
Thank you
HI Phil, yes, Please see my reaction in this topic, how I lathed it down. Just took me 20 mins 
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OK. Well that obviously worked !
Quick one : why not taping around the motor + reisenauer with metal tape ? That would make it somehow waterproof, while still cooling down ?
Well I tried that in my first design(with the blue motor), however there are some concerns:
- How do you waterproof the front end of the motor (near the mast)?
o Perhaps you could glue the front part in a mast clamp - The motor is not designed to distribute the forces trough the motor housing, my blue motor was made of very thin aluminium.
o Perhaps other motors are constructed more beefy and have a stronger body - The Reisenauer only has a bearing, this bearing is not waterproof.
o This is why you need some kind of housing around the reisenauer with a lip-seal.
Not sure if tape would work; don’t forget that you have about 0.1bar of water pressure under 1 m of water. Water will slip trough tiny gaps(capillary?) very easily! ‘somehow waterproof’ is not good enough 
Thijs please one more question…
Where did you get that coupler which you screw on the Reisenauer ?
When looking at Reisenauer catalog, I see only a 10mm shaft and no coupler ?
Thanks again
This is just how it’s delivered. You can screw in a m10x1(fine metric!!!) Shaft.
I lathed a new shaft at the workshop at my work.
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I found these guys in the UK:
https://www.accu.co.uk/en/double-ended-threaded-bars/469050-HTBD-M10-80-13-A4
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OK… See the way the Super chief is delivered… No coupler…
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Will not fit , need to be m10x100 ( fine)
For the super chief with the polygone 6x7 shaft you can use this:
For the super chief round 6mm shaft , you can use a " classic" coupler
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