Boats and foils comparison

[MaxHugen]

View attachment 433007

I can't argue with the force vectors shown in the diagram, but...

The first time I went skydiving, it was in a small plane - IIRC a Cessna. The RHS door is taken off for easy egress, and as I was the first to jump, I was right at the open door. When the plane banked right, I expected centrifugal force to keep me in the plane, but I nearly fell out, there seemed to be no force there at all!

Go figure?  :blink:

 

[The Advocate]

I hate you strider!  :angry:

Mercedes F1 COR

 

[jaysper]

I can't argue with the force vectors shown in the diagram, but...

The first time I went skydiving, it was in a small plane - IIRC a Cessna. The RHS door is taken off for easy egress, and as I was the first to jump, I was right at the open door. When the plane banked right, I expected centrifugal force to keep me in the plane, but I nearly fell out, there seemed to be no force there at all!

Go figure?  :blink:

Strange.

I went for a ride in one of our Air Force's helicopters a few years ago and was facing outwards towards one of it's (open) doors.

Whilst I did have a seat belt on, I never felt it kick in as the chopper went into a spiral.

 

[The Advocate]

I can't argue with the force vectors shown in the diagram, but...

The first time I went skydiving, it was in a small plane - IIRC a Cessna. The RHS door is taken off for easy egress, and as I was the first to jump, I was right at the open door. When the plane banked right, I expected centrifugal force to keep me in the plane, but I nearly fell out, there seemed to be no force there at all!

Go figure?  :blink:

It may have banked right, but did it turn right h34r:

I have a similar experience, different outcome. I was in a rescue helicopter sitting in the jump seat. As we approached the target the crew chief opened the door closest to me and shortly there after the pilot threw the chopper into an extremely steep banking turn that had me looking out the open door directly at the water. At that moment the only thing I could think of was the pissy little polyprop sash belt I was secured to the seat with and how I wasn't falling out. Then I realised I could hardly lift my arms...

 

[DryAxE]

So much talk was already about the foils, what im curious about is why Italians who are in really good stable control of their boat fly the hull so high, especially at high speeds. I think they do it intentionaly. Is the pressure at the hull height really that beneficial to VMG or is it worsening it by pushing boat away from course.

Can italians with their hull shape and leaving some gap create venturi effect under hull at high speeds to suck their hull down and increase righting moment?

Its strange because Italians have never bothered with batwing sail to lower point of power delivery, seems like they have enough righting moment to carry more sail area higher up. Those two boats are really different beasts.

 

[The Advocate]

So much talk was already about the foils, what im curious about is why Italians who are in really good stable control of their boat fly the hull so high, especially at high speeds. I think they do it intentionaly. Is the pressure at the hull height really that beneficial to VMG or is it worsening it by pushing boat away from course.

Can italians with their hull shape and leaving some gap create venturi effect under hull at high speeds to suck their hull down and increase righting moment?

Its strange because Italians have never bothered with batwing sail to lower point of power delivery, seems like they have enough righting moment to carry more sail area higher up. Those two boats are really different beasts.

It would make some sense that the faster you go the higher you fly to maintain the same pressure between the hull and the water.

I might be talking shit though.

 

[mauriciogfj]

I can't argue with the force vectors shown in the diagram, but...

The first time I went skydiving, it was in a small plane - IIRC a Cessna. The RHS door is taken off for easy egress, and as I was the first to jump, I was right at the open door. When the plane banked right, I expected centrifugal force to keep me in the plane, but I nearly fell out, there seemed to be no force there at all!

Go figure?  :blink:

Radius does it!

First time skydiving? I'll bet you were focused on gravity.

 

[MaxHugen]

It would make some sense that the faster you go the higher you fly to maintain the same pressure between the hull and the water.

I might be talking shit though.

It's likely to be a factor of the sea state... if there are "waves" (hahaha) they will want to fly a bit higher to avoid them.

Could also be that at high speed the flight controller has way less reaction time, so plays it a bit safer and stays higher.

But I could be talking sh*t too.

 

[The Advocate]

It's likely to be a factor of the sea state... if there are "waves" (hahaha) they will want to fly a bit higher to avoid them.

Could also be that at high speed the flight controller has way less reaction time, so plays it a bit safer and stays higher.

But I could be talking sh*t too.

I think yours is more believable shit lol

 

[MaxHugen]

Radius does it!

First time skydiving? I'll bet you were focused on gravity.

Radius... ah, that's what it must have been!

Actually, you had to climb out onto the diagonal wing strut (overhead wing), and that was rather awkward and ... unpleasant.

Didn't have an arrow with me, so I just ignored gravity. :lol:

 

[mauriciogfj]

^^Skyding, riding in a foiling monohull? Always keep your grey bold gravity arrow at hand.

 

[MaxHugen]

^^Skyding, riding in a foiling monohull? Always keep your grey bold gravity arrow at hand.

OK... also need a supply of yellow circles on the foilers, so you know where you've been.

 

[The Advocate]

I really want to make up a big grey arrow with GRAVITY printed on it and go to the local indoor sky diving centre lololol

 

[MaxHugen]

I reckon the outboard wing is fully ventilated when the tip is out. It's easily visible from the overhead shots. Could be why etnz has pitting all around the hinges on the outboard wing. Funny how the pitting on the inboard wing is most visible on the leading edge...can't find the shot right now but was notable.

Ventilation wouldn't be the cause of pitting, that happens due to cavitation. I too would be interested to see that pic if you can find it.

Cavitation does often begin right at the leading edge, as that where there's a massive drop in pressure.

 

[MaxHugen]

I really want to make up a big grey arrow with GRAVITY printed on it and go to the local indoor sky diving centre lololol

Haven't been to an indoor centre, looks like fun!

Funny thing is, when free falling, there isn't so much a sensation of falling, it's more like being held up by a 120mph wind - similar to the indoor stuff I guess.

 

[The Advocate]

Haven't been to an indoor centre, looks like fun!

Funny thing is, when free falling, there isn't so much a sensation of falling, it's more like being held up by a 120mph wind - similar to the indoor stuff I guess.

Indoor centres here use kmh wind, not sure how that differs in the experience

 

[MaxHugen]

Surely it will help downwind VMG, where you don't want to counter leeway. Being able to favour generating lift on the more horizontal side should allow a more neutral setting on the side that would otherwise push the boat upwind

For sure. Downwind, leeway is your friend. No doubt why they sail with 2-3° less foil foil cant too.

 

[The Advocate]

For sure. Downwind, leeway is your friend. No doubt why they sail with 2-3° less foil foil cant too.

Wouldn't that have more to do with the vertical component of gravity acting on the resultant rotational force of RM vs sail loading?

 

[MaxHugen]

I would think so..showed as white in the shot. I'll keep looking for it,I think it was a zoom of a weta shot about a week ago. The hinge area makes sense as low pressure in the cavity, the leading edge wasn't mentioned and doesn't make sense to me.

Cavitation will occur where the local pressure is lower than the water vapour pressure. As well as the leading edge, the upper hinge point is definitely another candidate to promote cavitation:

 

[Stingray~]

Wouldn't that have more to do with the vertical component of gravity acting on the resultant rotational force of RM vs sail loading?

Oh, absolutely!
 

Glad you brought that up Victor! I had completely mistaken the component of gravity’s vector..