Hydroptere Pitchpoles

gui

Anarchist
The guy on the vid' simply said they broached and capsized in a gust. They tried to ease the solent, but apparently too late.

DL, listen and learn from the people who know. "Most" (some?) of us in that forum have more designing/building street cred than you will ever have, and yet,

we keep our ego in check and stfu. There is no replacement for hours in the water, so be quite and learn from Bora et al.

 

βhyde

Super Anarchist
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There is no active control besides the rudder attached to that steering wheel.

Surface piercing hydrofoils dont need active control esp in a tractor config which is what l'hydroptere is

All it does is turn the rudder left and right
You may have already covered this, but I’m not sure I understand. Are you saying that the hydrofoil on the rudder is in a fixed position? Or are you saying that the driver just doesn’t deal with (i.e. someone else is trimming it)? I assumed the rudder-mounted foil controls the pitch of the boat (as well as lifting) and the forward wave piercing foils automatically control height.

 

Monkey

Super Anarchist
11,058
2,689
Baltic I would like to disagree, everything I see says canard is when the control surface is in front of the static foil.
=========================

Not only are you nuts you're a real asshole publishing that w/o my permission.
Get over it Doug. You have made such a joke of yourself that being called an asshole by you is actually a compliment.

People like Bora or Thebault are actually out there pushing the envelope and experiencing the world of sailing on foils. They learn from actual experience and improve. Everything you spout off about is entirely based on your internet research into the success of others. I really hope you have realized that virtually everyone has figured out that you're not the expert you like to think you are. Stop trying to convince us that you're correct because your internet math says so.

 

Theoretic

Super Anarchist
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There is no active control besides the rudder attached to that steering wheel.

Surface piercing hydrofoils dont need active control esp in a tractor config which is what l'hydroptere is

All it does is turn the rudder left and right
You may have already covered this, but I’m not sure I understand. Are you saying that the hydrofoil on the rudder is in a fixed position? Or are you saying that the driver just doesn’t deal with (i.e. someone else is trimming it)? I assumed the rudder-mounted foil controls the pitch of the boat (as well as lifting) and the forward wave piercing foils automatically control height.
Seems to me there are a lot of confusion/disagreement in this thread what some of the words used actually mean. That includes not just canard but aoa, angle of incidence, pitch, and even control. At very least DL & bgulari are not using these words in the same way. Hope they would clear those out before continuing the fight on how things work.

In an airplane the pilot can change height in large quantities and air density as a result. Not so in foilers. A lift of all foils combined simply must be the same as weight, or the craft accelerates up or down, which is not wanted and can't be maintained for a very long. Since a distribution of lift between front and aft foils also have to match position of center of gravity modifyed by pitching moment due to sail drive & water drag, there is only one possible front foil lift value in any given speed & location of CoG. What reason would there be to change aoa of the front foil at which that lift is accheaved by changing the area of surface penetrating foils ? Doesn't it make more sense to just let the area change with changing speed and leave aoa as it is for near optimum performance ? If it does, then the rudder foil just needs to maintain the same pitch of the boat, no need to try to change it. Is this then called controlling of pitch or not ? Suppose some might argue not, especially if front foil can be adjusted during the run to change the pitch angle of the boat which the rudder foil maintains. Is this then called rudderfoil controlling pich or mainfoil controlling pitch ? Some folks here are not going to agree on the others on that question and that seems to me be the cause of the semantic problem & shit fight. Of course there are other reasons as well.

Ps. this post is not only about surface piercing foils of Hydroptere or moths but about all foilers real or not to make the semantics issues more clear. No point in fighting about reality when people are not even using "same language" due to semantics issues.

 

Doug Lord

Super Anarchist
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Cocoa Beach, FL
Limited glossary: http://www.foils.org/glossary.htm Note the definition of "conventional" and "canard" arrangements. This will help: http://www.foils.org/basfigs.htm

--angle of incidence: angle of a foil related to a fixed/design line on a boat like the static waterline(design static waterline)

--angle of attack: the angle of the foil relative to the flow.

--Example: a foiler may be set up with an angle of incidence of +2.5 degrees on the main foil and 0 degrees on the rudder foil. On take off weight may be shifted aft to change the angle of attack of the main foil to +5.5 degrees and the rudder foil to +3 degrees. After getting up on foils the boat will speed up and the crew would move forward. Moths are much more sensitve to crew movement that,say, a Rave.

pix from foils.org:

angle of incidence-------------------------------angle of attack

180px_Angle_of_incidence__28wing_29.png

300px_Angle_of_attack_svg.png

 
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NYBOZO1

Anarchist
808
17
"From Stalage 17, mail call) At ease, at ease.

Getting back on track to those of us not foiling around, where is the crash video?"

No kidding! If I wanted to talk physics I can take a refresher course.

I keep comin back to find the video and all I get is dippy Doug and his merry band.

 

Theoretic

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Hydroptere can change the lift of the foils by changing the angle of attack-but not underway.
You claim aoa can not be changed when underway when flow exists. From which can be concluded that you know that aoa means angle between incoming wlow & chord and yet claim aoa can be changed when not under way ; meaning no flow even exists => no aoa exists and think that to be a sensible claim ? ! ?

Further more lift can only be changed by changing the weight as long as we are discussing stable sailing during a record attempt, not trying to jump off the water. Yet you claim it can be changed by changing aoa when not moving without any indication on changing weight or CoG.

 

Theoretic

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I love the part where he implies i am not telling the truth about moving back in the boat, he still can not explain why I am doing it and what the advantage is. Anyone else want to take a stab?
IF his claim about the aft foil pulling down were correct, then the advantage of moving back on moth would be to reduce the loading on both foils and thus reduce drag and get more speed.
 

Theoretic

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I guess you know more, you win doug. You must not have seen all the times that i sit at the back of the boat and well over %70 of the total weight of the boat is being supported by the rear hydrofoil.

You are so messed up. The thing that actually controls pitch is the Angle of Incidence on the front foil, the rudder is a fine tune.
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Absolute Bullshit! You think you know what your're talking about but you're flat wrong.
If there would be 2 identical moths sailing in identical conditions on same direction with same speed & same crew weight & position, except they have different angle of incidence on front foil, then aoa of front foils still must be the same. Different incidence angle with same aoa means the pitch angle of boat must be different by the difference of incidence.

At which point of this explanation of mine about what bgulari wrote in bold type above does DL disagree ?

 

jfunk

Super Anarchist
2,530
4
I love the part where he implies i am not telling the truth about moving back in the boat, he still can not explain why I am doing it and what the advantage is. Anyone else want to take a stab?
Pretty certain I can guess, but I don't really want to join in this shit fight.

 

Doug Lord

Super Anarchist
11,483
21
Cocoa Beach, FL
Hydroptere can change the lift of the foils by changing the angle of attack-but not underway.
You claim aoa can not be changed when underway when flow exists. From which can be concluded that you know that aoa means angle between incoming wlow & chord and yet claim aoa can be changed when not under way ; meaning no flow even exists => no aoa exists and think that to be a sensible claim ? ! ?

Further more lift can only be changed by changing the weight as long as we are discussing stable sailing during a record attempt, not trying to jump off the water. Yet you claim it can be changed by changing aoa when not moving without any indication on changing weight or CoG.
================

Hydroptere has a waterballast tank in the main hull that -as far as I know- can't be altered underway. I could be wrong-they may be able to use the diesel to pump in or out. At any rate it is used to change the pitch angle of the whole boat thereby altering angle of attack of all three foils simultaneously. Further, they may be able to alter the main and/or rudder foils angle of incidence when not sailing-that is quite likely since it is possible on most foilers-at least the ones I've designed and the ones Bradfied has designed.

 

Doug Lord

Super Anarchist
11,483
21
Cocoa Beach, FL
I guess you know more, you win doug. You must not have seen all the times that i sit at the back of the boat and well over %70 of the total weight of the boat is being supported by the rear hydrofoil.

You are so messed up. The thing that actually controls pitch is the Angle of Incidence on the front foil, the rudder is a fine tune.
----------------------

Absolute Bullshit! You think you know what your're talking about but you're flat wrong.
If there would be 2 identical moths sailing in identical conditions on same direction with same speed & same crew weight & position, except they have different angle of incidence on front foil, then aoa of front foils still must be the same. Different incidence angle with same aoa means the pitch angle of boat must be different by the difference of incidence.At which point of this explanation of mine about what bgulari wrote in bold type above does DL disagree ?
-----------------------------------------

As long as the foils are equal area, the rear foils the same angle of incidence and the distance between them the same along with your other stipulations -you are right.

 

βhyde

Super Anarchist
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You’ll have to excuse me, I’m going to slash my wrists now.
The funniest part about that exchange is that by far the most coherent part of that exchange comes from the guy for whom English is a third or fourth language.
Ain't that the truth.

I think my brain has completely 'overlorded.' Yep, the needle on the the Lord-Load Meter is pegged in the red. I'm going back to PA where it's quiet and polite...

 

Theoretic

Super Anarchist
1,075
0
I guess you know more, you win doug. You must not have seen all the times that i sit at the back of the boat and well over %70 of the total weight of the boat is being supported by the rear hydrofoil.

You are so messed up. The thing that actually controls pitch is the Angle of Incidence on the front foil, the rudder is a fine tune.
----------------------

Absolute Bullshit! You think you know what your're talking about but you're flat wrong.
If there would be 2 identical moths sailing in identical conditions on same direction with same speed & same crew weight & position, except they have different angle of incidence on front foil, then aoa of front foils still must be the same. Different incidence angle with same aoa means the pitch angle of boat must be different by the difference of incidence.At which point of this explanation of mine about what bgulari wrote in bold type above does DL disagree ?
-----------------------------------------

As long as the foils are equal area, the rear foils the same angle of incidence and the distance between them the same along with your other stipulations -you are right.
1) Which part of those identical & except statement would allow any of those differencies you stated in order to me being wrong ?

2) how does me being right on that one explain your statement :"Absolute Bullshit! " on the post by you I initially responded to.

Are you taking that back now ? Or is there something else there in bgularis' post you still claim to be bullshit, if so what it is ?

 
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Theoretic

Super Anarchist
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Hydroptere can change the lift of the foils by changing the angle of attack-but not underway.
You claim aoa can not be changed when underway when flow exists. From which can be concluded that you know that aoa means angle between incoming wlow & chord and yet claim aoa can be changed when not under way ; meaning no flow even exists => no aoa exists and think that to be a sensible claim ? ! ?

Further more lift can only be changed by changing the weight as long as we are discussing stable sailing during a record attempt, not trying to jump off the water. Yet you claim it can be changed by changing aoa when not moving without any indication on changing weight or CoG.
================

Hydroptere has a waterballast tank in the main hull that -as far as I know- can't be altered underway. I could be wrong-they may be able to use the diesel to pump in or out. At any rate it is used to change the pitch angle of the whole boat thereby altering angle of attack of all three foils simultaneously. Further, they may be able to alter the main and/or rudder foils angle of incidence when not sailing-that is quite likely since it is possible on most foilers-at least the ones I've designed and the ones Bradfied has designed.
So when those folks sheet in harder that does change heeling forces, which can be done under way. When that happens doesn't the lift forces on the foils change as well while under way ?

As far as I know they can't change dihedral angle while underway, so the change in lift on mainfoils should be plenty, propably much greater change than what some added ballast would cause due to changing pitch of the boat.

any comments on the meaning of expression "controlling pitch" in my previous post #184

 
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