# Looking for an engineer to check my hydrofoil math

I’m putting the finishing touches to a Fusion 360 add-in which computes ideal foil sections. It is based on particle-swarm-optimisation (thousand of machine hours of genetic improvements)

Are there any engineers here who might like to look at where I’m upto and tell me if I’ve left stuff out, or if anything looks wrong?

The input panel & main program look like this (it does air and water, foils and props):

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Mechanical engineering student. Have study fluid mechanics for multiple years now . But looking at your choice of flow (laminar or turbulent). I am not sure if your choice of flow is best . If you are using the prop outside of an enclosure it would seem to be a better assumption to have turbulent flow. This can account for riding in bodies of water that have current , down / up draft. Also as you turn you will disrupt your intake flow therefore a solid 99% of the time your intake direction is changing.
It would be best to use laminar flow if your prop is enclosed in a system such as a jet intake.

Thanks @Dav-25 ! I am baking in some defaults to my code, which efoil builders can get from my preset dropdown.

There are 4 different things my program will produce:
*. foil sections (for the “lifting” foil wings, and for the low-drag strut)
*. shroud for the prop (with optional lifting effect)
*. prop itself
*. cowling - the nose for the motor, and tail after the prop

I want to supply some as-close-to-real defaults as possible for each of the above. Your insight into the prop conditions is excellent - I probably would not have thought of that. I’m using the combination of “turbulence” and “finish” to derive the flow separation criticality - it just seemed easier to ask users “real questions” than ask them for an arbitrary number they won’t understand…

These are my defaults for the foil section and strut:

‘medium’: (water)
‘turbulence’: (Laminar, Average, Turbulent
‘finish’: (Rough, Average, Clean, Very smooth)
‘minspeed’:4, meters/sec
‘targetspeed’:7,
‘maxspeed’:15,
‘mintemperature’:5,
‘targettemperature’:12, degrees/C
‘maxtemperature’:16,
‘target_span’:0.8, meters
‘target_mass’:80 kilograms

Do they look sensible to you? My plan for the mass option is to tell them the chord if they tell me the length, so the foil is the perfect size for them (optimal performance for their weight). If they leave that out, they’ll need to hope they picked a suitable chord and span themselves.

What is a typical span and chord of a front foil on an efoil, do you know?

Numbers look very sensible and should work for the average person perfectly.

Not sure On the average sizes for the foils just yet still researching on them.
But from a raw assumption having a slightly over sized foil for the weight would be best.
More lift better than no lift.

Here is a better place for my answer.