These videos are great insight into the Lift design.
Does anyone know the motor connectors they are using?
The idea I had in mind when creating the thread … a place where users could post their retro engineering info even if I am aware that users who can spend 12.000 USD in such an equipment are not legion on this forum … Hopefully, as soon as the Lift eFoil appears in various places across the globe, comments and picts with valuable info for home builders should pop up …ESC, motor, cooling, remote control, …
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A call for pictures if you see one of them… plus two noticeable news from LiftFoils Instagram account:
- eFoil (world?) speed record (September 01 2018) credit to @carbon
What’s your top speed? - #9 by carbon - Builds - FOIL.zone
- first eFoil with folding propeller used when going down waves (September 10 2018)
- [liftfoils]watch the hand controller pass from hand to hand. That is the first shot with a folding propeller. No power.
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There’s no retractable prop. They just using the normal efoil in the surf.
Edited, they are folding and not retractable propellers.
When the engine is switched on, folding blades are spun outwards by centrifugal force.
When the engine is cut off, the pressure of waterflow forces the blades back in place streamline. Since the roots of the blades are linked with geared teeth, they open and close together with the same angle.
I’m not sure about that. Lift are so comfortably ahead of the competition that they can take time to test this kind of fancy prop not so difficult to 3D print or mill by the way.
They have probably been inspired by tests like this one from 2009:
https://sw12585.smartweb-static.com/upload_dir/docs/Test_YachtingMonthly_low.pdf
On boats, folding props have proven their efficiency. Prop open, you can get better forward speed and pull compared to a fixed-blade one. Then, when folded, the drag is so marginal that it is difficult to measure. This feature seems to be praised by Lift when going down waves.
Unlike our eFoils with fixed blade props and nozzle. When the motor is cut-off the drag is present and can be measured by a luggage scale towed by a boat.
The winner of the above tests: https://flexofold.com from Denmark
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Still collecting/gathering info…
In addition to what @Clarin has written in the previous post, I’ve noticed they have different names: Boat cam latch, Boat deck latch, Boat Latch, Hatch latch, Hatch Lock, compression latch. Sometimes, they are sold much cheaper without cam.
Although similar, they must not be confused with the pull (caravan) latches which don’t have cam (no compression needed) - 5 to 10 USD.
You can find the stainless steel models (SS316 only) on amazon, ebay, aliexpress - 12 to 30USD per piece:
https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=Boat+Hatch+Cam+Latch
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I think Lift is using this:
http://www.gemlux.com/catalog/Retail-Compression-Latch-Kits/5124-11-KIT
The logo is of this brand.
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Nice article about the Lift eFoil unboxing: https://e-surfer.com/en/lift-efoil-review/
“The Battery is made in Sausalito close to San Francisco by Lithos Energy”
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interesting: high energy pack: 140A discharge but at 10sec pulsing, cycle life yes but C/2 discharge and C/4 charge…
reading : 18650 with 20C discharge capacity ??? like 1sec pulse
Great review and Lifts product is nothing short of spectacular! Love it!
The Lift eFoil folding propeller:
According to LIFT, in the ocean swell, a switched-off motor = a folded propeller = more battery life
A few remarks though. So far I was thinking that propeller blades :
1- needed to be three and not two for max efficiency (as Flying Rodeo is doing)
2- needed to be twisted in order to cut through water and not push water (Straight blades = swirl so perfect for food mixers / Twisted blades = efficient thrust for propeller blades)
Food for thoughts:
Here, the Lift team seem to favour the two-bladed and hardly twisted propellers as in the 2009 Yachtingmonthly.com propeller test above:
Maximum speed p94: untwisted two-bladed folding Flexofoil prop faster than
twisted three-bladed fixed version
"(...) Interestingly, some of the best performers were two-bladed props,
which are widely assumed to perform worse than three-blade versions."
Forward Bollard pull p95:
" the three-bladed folding Flexofold – generated a greater bollard pull than the
standard fixed prop" (with twisted blades)
the two-bladed folding Flexofold – generated equivalent bollard pull as the
standard three-bladed fixed prop with twisted blades.
It would be interesting to know the bollard pull of the LIFT folding prop versus the standard fixed and twisted three-bladed props delivered with the LIFT E1 and LIFT E1 Sport efoils.
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While three bladed propellers are more common than two bladed, they are in general not superior. On the contrary: propeller theory says clearly that efficiency decreases with the number of blades. The main reason for five or seven bladed propellers on large ships is to dampen oscillations (= noise prevention).
Propeller design is a trade-off, to improve a certain aspect means a decline in one or more other aspects. So you have to decide which goal is the most important, depending on the special application of the propeller.
Yes its proven the fewer the blades the more efficient a propeller is but there are trades offs.
The open propeller to me is really dangerious. Infact any propeller-driven surfboard is ban in Canada by transport Canada becuse they are so dangerious and easy for a mistake/accident to happen. Its only a matter of time before some with an open prop gets really badly injured.
What about the ducted props ? Is the Canadian market also closed to models offering a ducted solution (LIFT, Fliteboard, …) so only allowed to waterjets (VeConcept) ?
Regarding the possible prop ban, among the existing solutions:
1- There is a patented “safety propeller”: Colin Chamberlain from Australia has added a thickened leading edge to existing metal propellers with low impact on performance.
First licensee, Turning Point Propellers of Jacksonville Florida https://turningpointpropellers.com/ has produced a whole range of the “Safer” propeller under their brand name, “Aegis.”
The patent filled: WIPO - Search International and National Patent Collections
The patent in pdf format here. I am not sure it applies to efoils or hydrofoils engines though.
It would be interesting if sbdy with sound CNC skills (David @Flying_Rodeo ?) could make a prototype of a propeller with thick leading edges (Inventor trail) or thick blades (first licencee trail) to demonstrate the inventor claim stating very low impact on speed.
2- the LIFT folding prop has already rounded blades which could be thickened and, better still, fold when hitting a hard stuff (arm, finger, knee…).
3- ring propellers offer a solution (seems that there is an efficiency issue due to rotating quard increasing the wet surface)
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Continuing the discussion from The Lift E1 eFoil thread - info for the DIYer:
In my limited experience I have never fallen on the prop. I have fallen on the mast, the board and the wing but never on the prop! I have smashed my head, broken a rib and cut my arm. The sport has its inherent risks as all sports do, let common sense prevail. This is the reason I wear a helmet and impact vest.
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I did talk with Transport Canada and they were very clear that ANY PROPELLER DRIVEN SURFBOARD with our without duct is ban in Canada is what I was told plus a $350 fine if caught using one. Jet driven surfboards are allowed.
Those rubber props I saw on this forum last year, they really are great for a family boat that does lots of towing…
You really have been through the wars!! An impact vest is a non-negotiable in my opinion. They make such a difference when you fall!
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Does your impact veste keep you from drowning if unconscious?
Some are rated 50N
I am looking for 100N
I have a dakine impact vest. Use it for wakeboarding, skiing, tow-surfing. It’s amazing.
Dont be too sure, that you will fulfill the law by a jet versus a propeller driven surfboat. I found this:
Remote-controlled Vessels and Propeller-driven Surfboards
1006 No person shall
- (a) tow themselves using a vessel that is operated by remote control; or
- (b) operate a propeller-driven surfboard-type vessel.
Prohibition Against Careless Operation
1007 No person shall operate a vessel in a careless manner, without due care and attention or without reasonable consideration for other persons.
https://laws-lois.justice.gc.ca/eng/regulations/SOR-2010-91/page-18.html
It also could mean, that no surfboards or Efoils or whatever are allowed due to the risk of loosing control and the resulting risks for other persons.
Are you sure, that an impeller is not a propeller? And what is the difference in risk between a well ducted and hidden prop compared to a jet? Bans and laws can be changed, sometimes very quick. So if it turns out by any accident, that there is a high risk to be injured from a jet driven board which is out of control, the law can be changed. I personally think, the highest risk is the foil itself. On a surfboard the highest risk comes from the fin(s). Fins and foils are like swords, especially the trailing edge and the ends. I once dropped a mylar sail on a upward down laying surfboard and the fin cut it directly with ease.
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