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RC Surfer

Old 02-03-2012, 09:54 PM
  #3826
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Hi Kitebook

Love your Maths ..................................LOL

LOVE your board even more - really a very nice looking build - well done !!!

As your figures show - when we enlarge any vessel in size - most all the considered factors increase 'exponentially'. 4.4 kg's verses 1.2 kg's Considering - your board is roughly only 30% longer (1/3) = its almost 3 x heavier. Pretty steep curve.
The overall aqua dynamic drag of a bigger board due to its greater surface area - adding its greater weight - requires far more POWER and battery amps to get a good run in.

Personally - I to like the bigger size board - building the Large Scale F1's - but I finally chose 2ft as the size when I considered the overall equation - wanting to produce a product that is affordable - to be shipped affordably 'globally'.
Shipping by Air- under 1.5 kg's globally from SA will cost only $ 50 ( inexpensive)

With the lighter board - one can run the smaller motors - esc's and battery packs - ( cost considerably less) and still achieve a good power to weight ration. In the case of any electric breakdown - its not going to be a big expense. Having raced boats and Jetskis in the surf for a number of years I learnt that SALT is a formidable enemy - somehow- it always seems to eventually win.

I am also hoping that the lighter set up ( less load) will result in 'longer run times'

Regards
Dominic(YPC)
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Old 02-03-2012, 10:20 PM
  #3827
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Hi itsfishi

There are a number of things to consider ?

You mention that it runs better with a 3s - than the 4s - that deduced could be that the 3s is lighter aft - therefore CG of the board is further forward lowering the nose - and the 3s is producing less speed.

Maybe you could try adding stick on wheel rim weight to the nose of the board on top with the 4s pack ( say 150 grams) see if that keeps it flat -er

I would also like to know what the angle of the drive shaft thrust line is and where it projects in relation to the boards CG. ( how far in front or behind the CG)

Remember that your board has a relatively FLAT bottom - not a V- so any type of ripple on the water also propels it out of the water.
It is very nicely balanced when it is airborne.

Personally - I think its a tad to fast for what its for (surfing) the hull/setup is not for out and out speed.

- IN THE SURF - I would want a board that is tail heavy/nose up - I dont think you would be running those lengths/speed in the surf. A heavier tail should be better for carving and preventing the nose from digging in.

If you like - try a smaller prop

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Old 02-04-2012, 02:04 AM
  #3828
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hi dominic yeah fast but there are times when a burst of controllable speed is needed and my goal has always been to ride some big waves and then smooth speed will be key, but just trying to show what happens i think the 4s just really shows what is happening at a lesser extent on 3s and if i can get it too run good on 4s then 3s will just be even better.

just did a quick vid to show you the thrust line cg etc hope it helps.

cheers

[youtube]http://www.youtube.com/watch?v=t2jmvusbN3I[/youtube]
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Old 02-04-2012, 07:13 AM
  #3829
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Hi itsfishi

You've got me scratching my @$$.............................LOL
The video's are a great help.

All hulls have a suitable 'hull speed' it may just be that you are pushing the envelope with the 4s. Given for the most of it - rc surfboards are flat hulls - unlike a v hull that cuts the water- they will have a tendency to be very susceptible to bouncing of little ripples which is well illustrated in the video. at times accentuated when the board hits some of the bigger ripples.

If you have water skid and hit some small swell - one also tends to bounce of the water.

Does the board bounce on absolute 'flat' glossy water.

I have studies some dynamics considered in 'BIG WAVE BOARD DESIGN and some designers have introduced a shallow V into the board to avoid/eliminate the 'bouncing' experienced when the surfer rides the big wave face.
I have shaped our board with a shallow dihedral - hoping it will help 'cut' through the ripple.chop and eliminate the bounce.

It seems like you have modified the angle of the shaft on your board - it seems to be straighter than at the usual more negative angle.
Traditionally - a negative drive shaft will bring the nose down. if the imaginary thrust line travels through/or is behind the CG in the length- that will drive the nose down ( the steeper the angle - the more so.)
-If you drive is straight - parallel with the running surface of the board- the thrust line will project ahead of the CG - intern promoting lift in the nose, especially if the nose bounces up.

Your CG between the 3s and 4s is not as what one would naturally assume to be obvious- as you have split he 4s pack partly to the front so in effect your 3 s pack has a more AFT CG than the 4 cell. The 3s pack has proven to run better - given that it has more weight aft may add to the consideration that your drive thrust line is to straight, as it will be allowing the hull to ride/flight deeper aft which is increasing the shafts negative thrust angle.

THIS IS ALL JUST ASSUMPTION - BRAINSTORMING - THOUGHTS - Hope it helps.

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Old 02-04-2012, 07:36 AM
  #3830
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Default RE: RC Surfer

Hi itsfishi

You've got me scratching my @$$.............................LOL
The video's are a great help.

All hulls have a suitable 'hull speed' it may just be that you are pushing the envelope with the 4s. Given for the most of it - rc surfboards are flat hulls - unlike a v hull that cuts the water- they will have a tendency to be very susceptible to bouncing of little ripples which is well illustrated in the video. at times accentuated when the board hits some of the bigger ripples.

If you have water skid and hit some small swell - one also tends to bounce of the water.

Does the board bounce on absolute 'flat' glossy water.

I have studies some dynamics considered in 'BIG WAVE BOARD DESIGN and some designers have introduced a shallow V into the board to avoid/eliminate the 'bouncing' experienced when the surfer rides the big wave face.
I have shaped our board with a shallow dihedral - hoping it will help 'cut' through the ripple.chop and eliminate the bounce.

It seems like you have modified the angle of the shaft on your board - it seems to be straighter than at the usual more negative angle.
Traditionally - a negative drive shaft will bring the nose down. if the imaginary thrust line travels through/or is behind the CG in the length- that will drive the nose down ( the steeper the angle - the more so.)
-If you drive is straight - parallel with the running surface of the board- the thrust line will project ahead of the CG - intern promoting lift in the nose, especially if the nose bounces up.

Imagine a see-saw - if you pushed it upward behind the pivot point (CG) - the opposite side would 'go down' - if you pushed it upward beyond the pivot point, the opposite end will 'go up'
If your force was going parallel ( like a straight drive line) with the see-saw - it would' no trim' effect on the tilting.

I have always found that a degree of negative trim - behind the CG is ideal - as the nose rises as speed increases, due to hydraulic lift from the water the the lift of the aerodynamics getting under the hull - the negative thrust line counters those forces and drives the nose down - if you find the ideal negative degree, the hull should run flat.
Its a calculated guess with the 'fixed drive shafts.

JIMMI and Kite effectively are achieving the same net effect with the 'rocker' (wedge) driving the nose down.


Your CG between the 3s and 4s is not as what one would naturally assume to be obvious- as you have split he 4s pack partly to the front so in effect your 3 s pack has a more AFT CG than the 4 cell. The 3s pack has proven to run better - as you say it may just be that the unit is 25 % slower and therefore the problem is less obvious.

THIS IS ALL JUST ASSUMPTION - BRAINSTORMING - THOUGHTS - Hope it helps.

Regards
Dominic (YPC)
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Old 02-04-2012, 09:38 AM
  #3831
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Itsfishi

Just watched your last vid... take the rudder off,put a straight edge on the end of that board...between the tail and towards those 3,4 marks. Are you getting a 5mm gap of JIMI Rocker at your rudder hole? It does not look like it in the vid. Build up the tail until you do. Give it a nice smooth concave out the back. IT WILL SOLVE EVERYTHING....Promise! it is worth the work.



My Board is a little larger, so I put in 6mm....get something your desired thickness and build it up the tail until it easily slides under the straight edge...

I shaped my current board flat half way then put in the 'V' out the back (1/4 inch on each side) right threw the JIMI Rocker. It was easy to do before 'glassing the blank foam...a little mo work for the plastic boards.
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Old 02-04-2012, 09:43 AM
  #3832
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This site is still not right......
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Old 02-04-2012, 10:10 AM
  #3833
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Thanks for the info and pics Kitekook - very informative.
Much like a Trim Tab on a boat hull.
Regards
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Old 02-04-2012, 07:57 PM
  #3834
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Well Jim sent me some photos of yesterdays' session...These were taken in Ocean Beach near Dog Beach and Avalanche (3 miles from where I live...my home break I guess you could say[8D]) photos taken with a Nikon D80.



pretty good jump off a little ramp



really working on staying off the throttle...work the wave, stay in the wave...aaahhhhh



I think were jamming over towards that glassy wave in the back.....no,[X(] not that monster way back there! I did try to go out there a couple of times...problem was the sets would hide Melika from me...I would lose sight for what seemed forever...had to play closer in just to see what was going on.



She just looks so athletic compared to the old Lisa model...A photo of Carissa Moore was my inspiration when shaping Melika....Carissa gets really low.



Melika has taken everyone by surprise. I have spoken to some very stoked Surfers the past couple days.



Money Shot ! We like to thank all our sponsors...especially the guys at Channel Island for their great designs....

All in all, this is what I had been dreaming of since I started with that wild idea...'I could do that'...after viewing the Maui********s How to DVD !!!



Here she is with her bigger sisters before getting glassed...


It took 4 months, finally, I have a model that I can be satisfied enough with to Just SURF!
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Old 02-04-2012, 08:29 PM
  #3835
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Cool thing is, that board will shred those set waves.
Like you said, just need to be able to sea it.
I had that problem at the Bro Down, The larger hulls will be better at it
as Maui John & Randys boards were easier to spot.
The Line up was pretty far out.

Looks like it was a pretty big day, my guess easy 8 to 10 foot faces ...
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Old 02-04-2012, 09:29 PM
  #3836
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Oh boy....

Jim sent this email after I sent one thanking him for the photos:

http://ireport.cnn.com/docs/DOC-741936?ref=email or maybe this link .....I posted 7 photos and tried to tell your story...i am NOT a writer and I get criticized on CNN cause of that .....i say screw em ...i take photos and hopefully they tell the story ...

He did say CNN
[X(][&:]

I like this photo he did not originally send:



and,yeah, thats my ugly mug, I wasn't going to bore you with[:'(]

Melika sure gets a lot of attention...who knows what will happen when she gets near one of your surfer 'dudes'
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Old 02-04-2012, 11:07 PM
  #3837
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Kite:
CNN ! Ya Brah !!!
Great Article ...

The "Path" Gets Clearer by The Moment.

Just need YPC to email to dial in
South Africa.

YPC Give me a shout surfcurls@aol.com
Some Big stoke coming your way.
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Old 02-05-2012, 12:08 AM
  #3838
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So Cal Bro Down #1 Was A Blast.
EVENT # 2 Is in the works for May.

Location / Date : TBD
Break Sites From OB - OS Looks central.

I think a Quarterly "Board Meeting" Is a good start ...

Just a thought,

Curlz
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Old 02-05-2012, 02:04 AM
  #3839
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Working on an NQD!

No hurry.

JIMI
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Old 02-05-2012, 02:10 AM
  #3840
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dom n kite thanks for the info its very helpful,

dom i had changed the angle of the driveline to try and fix the problem but from what you are saying i think i had the theory wrong or maybe just flattened it out too much, thats a big job doing the shaft again so im gonna do the jimirocker again and see how that goes, i just would love it to hammer without any added drag. will let you know how it goes. thanks again guys. oh and both of your guys boards look sick cant wait to see some vid.

later
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Old 02-05-2012, 04:24 AM
  #3841
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Hey itsfishi

Its all a pleasure ! - fortunately in most cases there are many ways to 'skin a cat' whichever works for the situation is good enough.

The JIMI Rocker will work well - like a trim tab on a boat - apply some light weight body filler- make it a tad more than what you reckon would be good.
Take it for a run - if the nose stays down to much - having a flat sanding block to reduce the wedge. trim/tune it to the desired running angle.

Regards
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Old 02-05-2012, 06:31 AM
  #3842
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Great stuff guys, cool additional pics Justin-San!

Looking forward to another meet soon!

Sure would like to see the video when John can get it all edited, don't forget to add blood spurting outa that surfer's back, the one I ran over with Justin's board!!

Hitting up Homey Depot for PVC for another stand and some hardware to work on the nose ridin' longboard...hoping to glass the deck and radio compartment today...

Keep the stoke!
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Old 02-05-2012, 08:06 AM
  #3843
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Quote:
ORIGINAL: surfcurls

So Cal Bro Down #1 Was A Blast.
EVENT # 2 Is in the works for May.
What ever we do PLEASE not Cinco de Mayo weekend....I would have to quite my job before I could go anywhere 5 may weekend....

Oceanside always has great surf events...and not much farther than last time.
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Old 02-05-2012, 09:56 AM
  #3844
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Agreed on that weekend, the only time of year it remembered that those ships bound for Mexico with a cargo of Mayonaise went down!

Kitekook, need a lead on where you bought the stainless studs for deck mounting, was disapointed to see that Home Depot has discontinued 2 whole drawers of stainless and Nylon hardware, the only 2 drawers I would pick my RC Surfer hardware from!!

Like to buy some from you, that or hit up McMaster Carr next week and order some!!
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Old 02-05-2012, 02:12 PM
  #3845
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surf here is in the 6 ftb range today and the point breaks are pumping but the wind is picking up quickly. did the tail last night just got to sand it back then ill be heading str8 to the beach

later
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Old 02-05-2012, 06:16 PM
  #3846
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Saildoggie

I bought all my stainless from the Bolt Depot.com
West Marine and HD will robb you blind. They have it there and it makes you want to pay there price and out the door.
I bought a bunch...
what size you need?I have 6,8,10 I used 8 last time and just got the 6's ...maybe big enough( for sure 26in models) the 10's were pretty big, but good on the 36in model.
how many?8?
address?
a photo of that stiletto you have[X(]saw a post on another forum....land yachts are my next project. especially since I have promised myself 100 battery packs before I build another surfer...hope I'll remember how
PM me, I'll just gift you a set
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Old 02-05-2012, 06:28 PM
  #3847
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Wow, you saw a pic of my Landsailer? Funny man, I have one of the prototypes, was working with the designer, Mr. Weber.
Mine does not have the production fiberglass fuse, rather an extremely durable blow molded Flat Bat!!
Not sure I even have a digital picture of it...still have it, real kick in the ass to sail, very fast!!

Post up a pic of the studs you used, are they just bolts????

Did a little work on my longboard today...this one is more inventing than building trying to squeeze the wench in there...

Gotta hook up for a session some time soon, your board looks awesome!!
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Old 02-05-2012, 07:25 PM
  #3848
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Saildoggie

I used #8 machine screws (stainless) along with a regular nut(not stainless)screwed all the way down to give the epoxy more to grab onto......stainless wing nut to top it off
I bought 1 1/4 screws....leaving 5/8 exposed seems to be enough clearance with the hatch material I am using, and a nice amount buried for the epoxy to grab onto.

1 box of 100 #6922 - Machine screws, Phillips truss head, Stainless steel 18-8, #8-32 x 1-1/4" $7.84 $7.84 Shipped
1 box of 100 #2644 - Hex machine screw nuts, Zinc plated steel, #8-32 $1.53 $1.53 Shipped
1 box of 100 #2668 - Wing nuts, Stainless steel 18-8, #8-32 $17.69 $17.69 Shipped

1 box of 100 #6914 - Machine screws, Phillips truss head, Stainless steel 18-8, #6-32 x 1-1/4" $6.85 $6.85 Shipped
1 box of 100 #2643 - Hex machine screw nuts, Zinc plated steel, #6-32 $1.40 $1.40 Shipped
1 box of 100 #2667 - Wing nuts, Stainless steel 18-8, #6-32 $17.53 $17.53 Shipped

Boltdepot.com


Forgot to talk about the hatch seal material.....it gets no Respect I tell you...but is probably the most important! I use the recommended seal endorsed by Maui********s....

Home Depot MD Building Products 19/32 in. x 17 ft. EPDM Cellular Rubber Auto and Marine Weather Strip
don't expect to get it locally...it ships from Kansas I think maybe... Oklahoma
http://www.homedepot.com/h_d1/N-5yc1...&storeId=10051

works great! HD a little slow on the online orders.


the #6 screws looks good...probably good enough...I always overkill my builds, then complain they are too heavy.



I can send some hatch seal too....I bought plenty to save on shipping....you can buy me a burrito and Corona at the next Bro down.
PM particulars
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Old 02-05-2012, 07:37 PM
  #3849
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Wow, great stuff man!
Yes,I saw John's weather seal, looked awesome!!

You have a great find there on the sources, thanks!!!

Burried in work and home stuff, this build is going very slowly..partially due to trying to figure out how to make it all work and also fit...just have to walk away sometimes, not enough hair left to pull out!!

Sure hoping John gets the vid up soon!!
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Old 02-05-2012, 08:41 PM
  #3850
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dom and kite thanks again for all the help what can i say the board has never riden so well, flammin awesome put 5 packs through and had a great seshh at 2 diff spots,strong offshore winds was sick fun ran both 3s and 4s i like the 4s best the balance just seems better the added tail has changed everything, man it surfs so smooth now and at speed. was so tempted to try this one spot ive looked at for ages but its a spot where if you mess up she could easily end up on the rocks or if breakdown would mean a big swim with the offshore winds. so wussed out this time but when im sure she is solid it will happen, got a couple spots like that around here just dying to hit em.

stoked

later
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