YPC

Hey Bearcave.......good thought !

The crescents, as you mention, may well have been introduced as an after thought to improve the self righting - IF - the board was to light, cutting away the volume of the rail would decrease the effective buoyancy and therefore allow the board to sink better down to the required rotational axis - allowing it to self right easier.

This issue can be seen in the thicker custom boards - needing more weight, rather to sink the board down to its rotation axis line - rather than to counter the surfers weight.

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Common.......I'm waiting for that 'Headcam' footage..........even the test video you spoke about.......LOL

bearcave

YPC.... I never thoughtabout the self righting bouancy effect of a fat rail until I read whatyousaid many posts ago regardingall the variables to considerwhen thinkin ofweight needed to self right any board...

Just to keep your brain active here are some thoughts... (kyo/nqd versus boardshark)
I have a "boardshark" production board.I got it with a broken 'leaning' guy so i stripped it out electrically and added a leaky plastic 'Lisa' behind the guys feet... Initial tests showed me the board self righted very well even with LL (maybe due to the motor batt and driveline sunk much lower in the hull than kyo?)...... but did ride more flat, like not much leaning of the board in turns (maybe because of no cut-outs?....)

Anyway its a project for the future and the 'leaning' guy is in the cupboard atm I was just sharing some stuff foryou to sleep on...... Karl has always run the 'leaning' guy... reckon the maui crew know much about these boards....way ahead of the other two but i must say... The original Kyosho foam type hull is certainly a special board even if you have to build it like a custom.... and if anyone out there gets one i recommend4 things you should do.
No.1 you keep it in the box for nostalgia reasons.
No.2 copy it and make another with the current information available and make it work better.
No.3 know everything there is to know now and modify it as you build.
No.4 (my version) build it likethey say thencontinually modify the original mistakes/problemswhile enjoying the light weight foamy experience without worrying about how much you have changed its originality....

billybongo..... my last post regarding the batts was relating to a stock 30mm dia 1.4pich prop.... i tried a bigger dia prop good response slow speeds and was way fast but slow and gruntygetting there.... smaller dia gave better variablethrottle response and actually screamed at high speed but lost grunt in the slop..... temps were good in all situations 90amp seaking will be ample whatever way you go i am running same esc now..... actually that's a lie.... I amnow doing more waterproofing on it cause I hate it when they get wet and go zzzzzttt.... best bet calculate as much as you can then run everything at 70% of the stated max....

YPC if i ever work out how to upload my camera vision..... might be best i just show the relevent surfing/boating vision.. LOL

bearcave

[quote]ORIGINAL: YPC

IMO....I reckon....as I mentioned before- aerodynamics (WIND) really becomes a 'big issue' after 25 - 30 mph.....

As for the crescent cut outs in the Kyhoso - NQD boards - I've been waiting for what other Think.....!!
I dont believe they are chines - chines deflect water - creating lift - the crescent cut outs to me are quite ingenious. I believe they act much like a V hull would to a degree 'allowing the board to lean even more in the turns' yet maintaining a flatter more stable platform aft of the board in the straights
Its a partial stepped hull - rather than a V- hull......if you draw it out as a cross section - you can see the similarity to a shallow V bottom theory......
It should also 'allow' the board to ride flatter, rail to rail ( keeping the surfer more vertically upright) as it travels parallel to the wave face, due to wider greater symmetric shape ( the wider portion of the boards rail line) in fact being shallower in depth at the bottom, allowing the rail to fit into the waves radius better......hope that explanation made sense..

The 'safe theory practice' will tell you that you should not be running below 3.6 V /cell....which would be 14.4 v's per pack after the run....

I run the HK (inexpensive) micro digital 3.6 kg all metal gear servo's....... have not broken a gearbox to date.....I do run the single fin 'occasionally' - but - another ' bi-fin' plus is that it places very little force and load onto the servo. The two fins continually balance any applied force.....reducing the servo's load drastically.

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YPC hope you don't mind me posting this editedquote..... important stuff and with the 'crescent mystery"......

Anywaythe two fins of a 'bi-fin' continually balancing the load is way interesting.....never thought about the self balancing servo saving less flex in the cable system that a bi-fin couldacheive before.... may have less 'feel'but....the more i think about it the more i think i have to make one soon....

bearcave

Sorry to hog up all the space boring you all to death in kelp but just one morequestion........

YPC....regarding the bi-fin self balancing....thinkin whatever shaped fins one may usethey would need to be 'balanced' around the pivot point in relation to how much turning you intend to do.....in general terms do you have any thoughts on where the major loads on a fin would be... like is there more force near the board or at the tip or is it equal and just the area of the fin dictating the forces.... sorry just had to ask i don't get much time to play computer but when i do i do....

YPC

Hey Bearcave !... The most boring question ever asked .............is the question 'never asked'......... Henry Ford never claimed to know all things - instead - shared that his success was because he better knew what questions to ask the folk around him.......IMO - The late Steve Jobs had a similar approach............as my 3 year old Cassidy sais when I ask her a question......Google it Dad !........LOL- We are so fortunate to live in a era with 'so much' information at our fingertips ( excuse the pun) ....

The Bi-Fin.....definitely misunderstood and underrated......

The pivot point on a Bi-Fin in 'pretty close' to center of its width - which also eliminates the damaging 'impact' usually caused due to the unbalanced ' face leverage' a single fin would have, with its pivot point forward by at least 3/4' 's of the single fins width.
With a single fin - landing a big jump with the fin slightly skew - or slapping the board on its side after a kick out or a re-entry - endures a huge impact on the face of the single fin, which is transferred 'straight back' to the servo gearbox - With the Bi-Fin - their is close to 'zero' impact being transferred back. .....so - that combined with the effortless geometry of its 'steering, requiring very little torque to steer it.......its an awesome fin arrangement.......which I prefer way over a single fins performance.

The only point of force, when actuating a turn, would be acting on the outside face of the one fin and on the inside face of the opposite fin, ( this generates the lean and digs the tail in) the force increasing toward the end of the fin due to the leverage - that will bear a load on the pivot pin and pivot pin housing in the vertical plane, so you need to ensure that the pivot pin housing is well secured into the board......as with the single fin....

I flare the bottom end of the brass pivot pin housing tube, before fitting it, so that when I epoxy it into the board, it creates a healthy ring of epoxy at the lower end of the tube, increasing the bonded strength substantially. On the top side, I pre - countersink the housing hole - then - when the brass tube protrudes - I flow epoxy around it - once cured - trim the tube down, resulting in a strong circumferential bond at the top end as well.......This system has stood up to some serious hammering so far......


Ill make a photo sequence as I make up one for the board I am currently building and post the pics ! its as easy as abc........123............LOL



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surfcurls

The "chines" on the Kyosho actually do more, and dont aid in self righting. The figure was the key to self righting.

For example, Doms boards self right on a dime, yet his hulls have no Chines like the Kyosho.

The Kyosho Chine Design aids in carving and holding trim ...

YPC

Hey Curls............It did not take long for us to disagree again...........LOL

Also...knowing me by now......although 'I have shared my view' on why I think the the cut a ways can/do add value to the boards riding performance....... For yourself, rather than just making a blanket statement ......share some interesting theory to substantiate your view.
The thing that lingers with me, is that if such cut a ways worked well in the surf on a surfboard......it would be being used in the full scale boards......which it is not......?

SO !...even with myself and yourself tending to believe they may add to performance -The cut -a -ways "could also' very well play a significant part in self righting.

Just for the record Chimes protrude from a hull surface - the cut away could rather be regarded as a 'step' in the hull surface.


The Dude ( as with all Dudes) only rights the board through the first 90 degrees when the board is totally upside down. Once the dude is lying on the water surface and the board is at 90 degrees to the surface, what has to then happen is - for the board to 'sink into the water' deep enough to reach its Center rotational axis line ( usually close to center) when it reaches that point - the actual buoyancy of the portion of the board that is submerged, will be able to rotate around the center rotational axis and surface - completing the self righting process.

SO - by cutting away the thickness of the rail - the board will require LESS weight to submerge, as it will have less buoyancy - sinking down to the rotational axis easier.

If your board is TO BUOYANT - your dude will simply lye on the surface of the water and the board will rest on the rail - Hence I have spent so much time sharing the various calculations - demonstrating that a thicker board requires more weight to self right.

You could do a practical experiment by simply filling in the crescent cut away 'on one side' with some 1/4" polystyrene foam ( tacked in place)

Then place the fully equipped board in water and test the self righting capabilities compared to either side.

Chances are that the filled in side will not right - or - right some what slower than the cut away side.............

It could have been that perhaps due to a significant difference in overall weight from the 'original custom board' - to the 'production board' - the self righting was initially an issue for the production board, being more buoyant and lighter - so the easiest /cheapest thing to do was to modify the molds by adding in the crescents, to reduce the volume which would reduce the overall buoyancy...............

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bearcave

thanks YPC great info..... I now have more of a liking to the bi-fin....will try making one out of brass as a tester keeping the basic load principles intact but without the downforce tabs for a first go...

lookingforward toyour pics of 'easy as 123' too...lol.

YPC

Hey Bearcave.......pleasure mate !

Let me just explain to all thinking " Does this guy live on his PC " .......for those who do not know, my No1 daily priority is 'Home Schooling' my 4 awesome kids - at the moment they are all 'Studying' for the end of year assessments - so I am free'r as I watch over them, to respond in more depth to the current subjects being discussed.

So Bearcave....Rather use 2mm ( 1/12 th) aluminium as apposed to brass - ali is lighter and has more flex. You dont need to braze any parts.
The pivot pin is simply secured by a nut on either side of the Bi-Fins platform.

As for the 'Down force tabs - allow your self the length to add them - as you probably will...........

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bearcave

Always good reading your stuff YPC.... I know you are setup for home schooling and in this day and age if the planets all line up andallow you tohave a life and a happy family it is a good thing.... reckon you and Lisa Marie have it sorted good... ....and who doesn't live within reach ofa pc these days.

I have been thinkin for ages how i could solder a brass plate to the brass rudder shafts i use but maybewill think of the bolt thing with alloy... just don't like the nutscreating unproductive drag but.....

Anyway andbtw... the only "real" difference i noticed when i filled in the chines on an nqd was the reduced self righting.... just sayin.

YPC

Hey Bearcave........

You do need the 'platform' of the Bi-Fin to be a few mm's clear from the boards hull surface to prevent any surface contact that could result in a jam, especially with the possibility of getting weed or debris stuck in between. I dont think the nuts create any drag issue in reality.......although in theory as you say. it would spell 'obstacle'

If I was going to weld any material to go with a flush/streamlined design - 'Stainless Steel' would be the better option as by thickness it will provide a stronger unit all in all - especially for the required strength of the pivot pin needs.

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Have a great weekend all.....I'm hoping for some good surf this evening.......hope you all catch great waves !

YPC

HOT 'little' TIP..........TESTED !

Water entering up the stuffing tube is generally overcome by 'Greasing' the drive shaft within the stuffing tube. The down side can be - hassle - power sapping - messy.

I have run a few surf tests now,with a short piece of Silicon tube fitted over the end of the Brass stuffing tube / over a portion of the extending drive shaft. (tube ID equal to the drive shaft OD) I have only 'very lightly' greased the drive shaft..........nett result.... less drag - less mess - no water whatsoever comes past the silicon tube. ( acts like a crankcase seal on a crankshaft)

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surfcurls

Hey YPC

I Agree that The Channels / Chines add performance value, They might have designed them in for self righting
and maybe not. The channels are not a substantial height that would make much of a difference in weight.
Also, The rails on My New boards are 1.5 times thicker than the plastic models, and they self right fine.
I didn't increase the channel height to compensate the bigger rails.

I really think they act more like a displacement hull, as the boards turn very well.
Maybe it's the opposite in that they work at keeping the board on plane and less subject to having the
hull go into a 90 degree angle that would require self righting ?

No one will know for sure unless Kyosho or Wombarra "Chine in" on the subject.

One thing to look at is this: Why would they have been set in design if they only
were made to aid in self righting ? The boards spend 95% of there time above water
And it's proven that the correct weight of the figure VS Board will automatically self right ?

surfcurls

Proof Of My Chine Theory.

Chine Notes From Wiki ;

The first hulls to start incorporating hard chines were probably shallow draft cargo carrying vessels used on rivers and in canals.
The barge and later the scow used a flat bottom and near vertical sides,
which provided the maximum cargo carrying capacity (in both space and displacement) available for a given depth of water.

Once sufficiently powerful marine motors had been developed to allow powerboats to plane,
it was found that the flat underside of a chined boat provided maximum hydrodynamic lift,
while the sharp discontinuity at the chine enabled spray to be deflected away as opposed to riding up the sides of the boat.
Consequently, almost all boats designed for high speed on the plane are nowadays of hard chine construction.

YPC

Hey Curls......we agree.......our discussion on why 'whoever' designed the cut a ways into the Kyhoso board is purely speculative........

However......it is possible to 'prove' there effects.....

As I initially shared, they certainly will effect handling and aid in turning, even reducing surface area drag on the straights etc........

However - to debate your mentioned points on their self righting effects:

The Kyhoso board has a Step....a step is a step...reducing the running surface in its length, from one level to a lessor level
a Chine is a 'V' shaped type stringer in the hulls length that 'deflects' water back down from the hull surface, to the water surface, generating lift. If you had a Chine on a flat hull it would be near impossible to hope to lean it.

The actual calculated 'weight' of the cut a ways that you mention, is not the point at all - its the LESSOR BUOYANCY potential that the removed area has. The thinner the rail, the less weight it will require to submerge the rail. (like surfers who like 'thinner boards' for easier duck unders and ridding deeper in the wave) In the case of the Kyhoso the cut away seems to be as much as 25% of the overall thickness, which is substantial when calculating lessor buoyancy.

Comparing 'your boards' greater rail thickness, yet still self righting, would require comparing the 'minimum weight' the thinner plastic board would require to self right, which would be less, to realize the actual difference to prove the point.

It is NOT ONLY the weight and size of the surfer DUDE that rights the board......if you removed all the weight out of the board, it would 'not submerge' to its required Rotational Axis, therefore - it would simply float, lying on either of its rails, with the Dude floating on the surface of the water.......

One thing specific effect of the dude is 'if' the DUDE is WIDE - the Rotational Axis of the board will be shallower, requiring less weight in the board, but it will still need to reach the RA to self right.

So - to conclude....It can certainly be 'proven' that the cut a ways designed into the Kyhoso boards could benefit' surfing performance and self righting'......

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After all that........I may have convinced myself to try them...........LOL

bearcave

After many hours of wasted time I have some tips to share.

No.1. If you get a cheap Sony handycam without the right manual or PMB (picture motion browser) setup disk and you want to upload your vision to a pc (like duh) first thing you must do is update the PMB version to the latest version via sony.... and update your pc's microsoft stuff regarding vid uploads too... only took me 10hrs over 2wks to work that out...

No.2. If you have many many hours to work out how to edit the vid using PMB go for it..... on the other hand if time pooryou canconvert the vid to WMV and edit in windows movie maker..... It will look like crap but

No.3.been a long time since i visited myYoutubeits notthe same as I knew andnow to be a part of it willrequire manymore hours of time to work out properly what they are sayin..... if ever

No.4. Christmas is here and even though I am not santai will bevery busy till next year and this weekend was all i had to post something visional.... so for better or worse I took myNQD down to the boat rampfor a helmetcamtest.....

No. 4a.Yes if i get the vision a bit higher it might be better. If iwork out the proper editing it might be better. If i go to the waves it will be much better whatever (lol) But seriously I thought I would be able to see the screen and get my head around whats happening much better......... this camera stuff is going to be another big learning curve.

No. 5. YPC...while being totallyimmersed in ******** thisweek I amhoping to do a staino bolt and nuts rudder shaft with some alloy bi-fin'sbetween now andxmas for testing next year.....
Btw i have tried the fuel line over the propshaft seal it works good if you can secure it good to the tube.

Anyway I don't know how to do the Youtube to ******** forum thing properly either so i'm postin this now and hopefully the vid will come soon

bearcave

disregard this post i have to to more reading on how to do it............. later.......... [youtube][/youtube][youtube]http://youtu.be/sEtpQ2HilBU[/youtube]

powerpark

My Feedback: (1)

Bearcave . Nice video , looks like it can by tilted up and few degrees and it will be right on. It pans good and looks very clear. Nice Job!

bearcave

[youtube]http://youtu.be/sEtpQ2HilBU[/youtube]

bearcave

powerpark.... I tried two times to upload this vid but see nothing my end.... i've uploaded two other vids to this site (not mine)but they show up on the post.... how come you can see it and I can't...... "faark faark faark says the uncyberland knowing crow.....lol"

Btw thanks for likinthe vid (wish i could see it?). This boardis nothin spec has a fat ass and flat rocker from the dude's rear foot down... cg around 50%....
Itis an NQD plastic copy of a Kyosho Lisa, weighs about 1800grams has a slight tail mod and filled in rail chines.... 2200kv motor 3s lipo batt 30mm x1.4pitch propwith a foamy Kyosho 'dude 'as the rider...

Always remember flat water is good for testing and slalom waterskiing butnot the same as surfing waves.... and this boardis far from perfect thats why I like you read this forum.

Btwis anyone out there able to post the basic instructions of"how to uploada vid to this forum".... ...

powerpark

My Feedback: (1)

I cut and pasted the link. I saw it then on youtube. Yea this page is not very user friendy. 

YPC

Hey Bearcave.......IMO - your board is ready for the SURF !........its got great speed/power /stability and turns very nicely.

You should think of making up a kind of 'Sight' that comes off the helmet which indicated the Center of Frame......also look to use the basic Windows Live Movie maker which I do - its really easy and you can upload straight to Youtube once your done.

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kitekook

Well you got the [youtube][/youtube] part right...lol

youtube] http://www.youtube.com/watch?v=sEtpQ...ature=youtu.be [youtube
you have to use the entire address....
remove the "=you.be"

[youtube]http://www.youtube.com/watch?v=sEtpQ2HilBU&feature[/youtube]




As for 4a above...I tried the camera mounted to the radio...just did not enjoy the experience...it was too distracting...Surfing not as fun.

I mount it above my vision on my helmet, forget it, and let it rip!

RC HAWAIIAN STYLE

bearcaver



hibernation is over ,, its time for the bear to roar,, helmet cam -5 stars test vid 5 stars,,, next stop bellsbeach




maui john

surfcurls

YPC

Try The Chines, It would be great to have your expert take on the differences...

Bear
Great Vid, It's a rocket. Easiest way to uplaod a youtube here
is to go to the youtube video, copy that link, then hit the Youtube option
and paste in the link between the (2) [youtubes] Like Kite says, some links require
triming the extra "=%#@)*^" Some don't