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Author Topic: XRAD'S HYDROPLANE  (Read 12711 times)

xrad

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XRAD'S HYDROPLANE
« on: December 31, 2015, 12:47:42 AM »

OK, final treat for the new year, for me anyway... 


There is a sale on these 49in (hull 46, with strut 49) hydroplane 'kits' at nitrorx.com for 365$.  Would take me weeks to make, and I have the need to get back to a modern build after the pilot cutter and the chris craft corvette.


So I made the plunge.   It really is a well done hull, fairly thick on the parts that touch water and thinner on top, but looks strong enough for what I want. the seams look well done inside, too.  Separate electronic compartment in rear for radio and servo. Overall, the looks are very good, not quite proportionate to scale unlimited hydros, but close enough for me.


So how to power this beast?  I was considering MHZ jetcat power, but sinking 5000$ into the lake is not really where I want to be...although they are so cool! 


Anyway, chose a combo of toro esc and Leopard motor. The motor is a 1100kv ~30v 5698 and the esc is a toro beast 200A (800a max..maybe) esc. As far as esc design, this one is VERY nice. clean well laid out boards and water resistant sealed aluminum box. It is hard to see the scale of the motor, but it is big!  the shaft is 8mm diameter. It was on sale on ebay for 89$ new, can't beat that ! This should be more than enough power to turn a big 67/3 prop or near that on 8s. would like to get into the 60-70 mph range...will see...


I like to live on the edge (through my models) so the motor max voltage is ~8s, the esc max continuous amps is 200, esc max voltage is 8s, max motor draw is supposed to be about 208 amps.. pushing a big prop as hard as I can...gonna be close...but i have feeling this esc can easily handle this motor!  And this esc has a 5A bec which is super nice. not many esc's in this power range have a BEC. It is also fully programmable for timing and a bunch of other things via programmer or bluetooth or laptop.  And I can always set my throttle to 90% of full end point if needed...

I will add water cooling to the esc somehow. and I will have to machine a strut to carry the stainless 1/4 id bearings for the 1/4 flex shaft. The original was metric and had a square end for the 26cc gas shaft.  Easy for me to get 1/4 shaft parts/ props/ etc. from US dealers, so I am going that route for now. 
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PeachyPM

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Re: XRAD'S HYDROPLANE
« Reply #1 on: January 01, 2016, 08:01:01 PM »

Looks the business Xrad :-))
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #2 on: January 01, 2016, 08:40:49 PM »

Thx, Peachy!  I am not the first to convert one of these to electric, but AFAIK first to use a 1100kv 5698 motor.


Some progress today: Machined up rough shape of strut.  It is cut from 6061 alu. Machines well. I used a 12 inch miter saw to cut the 6x6 sheet down to a 3x2 block, and then machined this down to rough dimensions.  Waiting on stainless bore and flange bearings from chinabay.  1/4id 3/8th od. 10 for 10$ or something like that. Also found some nice stainless thrust bearings for the 8mm motor shaft and for the strut. So all forces that I can account for radially and axially along the prop shaft at strut and motor have been dealt with.  My only issue is that the flex shaft housing is flexible nylon/teflon (which will be deflecting all over the place at 70 mph).  I may be able to slip the 1/4 brass shaft housing through this as the new one is a bit smaller than the original shaft and teflon liner.


The most critical part of the strut is making the bore correct diameter and parallel to the strut. 


As for props: I have a 1/4 bore 70 x 1.6 3 blade and for fun, a four blade 67 x 1.7!  I know 4 blade is not the best at high speed, but fun to experiment.  The original gas prop is 79 x 1.4 2 blade.  But it does not turn anywhere near 30,000 rpm, which is about where I am aiming for with the smaller props!


More on props: Interestingly, it would seem that with a counter-rotating prop, and with the lower half in the water, prop walk would direct the stern to port, and thereby directing the bow to starboard (right turn). So why is the rudder on the right?  Well, it must be countered by the turn fin, placed on port side (which this model does not have)   So do I add the turn fin?  I guess I would if I only wanted to turn to the left....  I was actually considering using MHZ 1 into 2 transmission to drive 2 smaller counter rotating props and using a centered single rudder.... I was also considering using a twin rudder set-up, but the less drag the better.  I watched a few videos of this hydro with the high mounted 26cc gas engine.  She still held a pretty straight course, but leaned a bit in the turns.  Of course, I suspect gas engine speeds did not exceed 50 mph.


Also, got a holux gps tracker for cheap.  tested it in my car, works great, and easy to use. It is about 3x2 inches. plan to tuck it into the hydro and test speed with different set-ups...nothing new for fast electric, but now prices have come down on all the parts for this build, so  time to test.
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PeachyPM

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Re: XRAD'S HYDROPLANE
« Reply #3 on: January 01, 2016, 08:54:18 PM »

Like the idea of using a GPS tracker for speed tests... Gotta get me one of those! %%
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derekwarner

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Re: XRAD'S HYDROPLANE
« Reply #4 on: January 01, 2016, 09:27:47 PM »

xrad.......what type of miniature 1:2 splitter counter rotating output gearbox can handle the power/speed of the MHZ1? .... Derek

Idle GG-Turbine speed 50000 RPM
Maximum GG-Turbine speed: 175000 RPM
Compressor Pressure Ratio 2:1
GG-Turbine EGT: 480- 730C  (896 - 1346 F)
Mass Flux 0.14 kg/s
Idle Output Shaft Speed 6000 RPM
Maximum Output Shaft Speed (depending on gearbox version) 19000- 35000 RPM
EGT: 300 - 360C (572 - 680 F)
Power-shaft speed: 19,000 - 22,000 RPM
Power: 8 kW (11.2 hp)
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #5 on: January 01, 2016, 11:03:22 PM »

Glad you asked!  The jetcat turbine is not directly coupled to the driveshaft that runs the props. It is coupled by the turbine hot air thrust acting on a secondary fan that is attached to a second driveshaft. This is a 'fluid' coupling located in the hot exhaust section of the MHZ jetcat combo. The box-like structure on the rear of a MHZ jetcat marine turbine is the reduction gearbox and output shaft with 1/4 flex coupler. That is why you hear the turbine spool up before the props turn (the electric motor will have full torque from the start). This secondary shaft drives a reduction type gearbox so that at peak power/rps of the main turbine/ the secondary shaft gearbox output is at ~30000 rpms. Therefore, driving the next 'splitter' gearbox is not really an issue, especially if it is made to handle a tuned 30cc engine. But there is a lot of power loss though the gearboxes and the fan to fan coupling.

I was considering using this gearbox with the 5698 and putting one center rudder...but I wanted to wait until I see how well the single prop works. My biggest problem is keeping costs down. Once you get into high voltage esc's for some reason the cost goes WAY up, anywhere from 400-1000+$'s. crazy! The boat+motor would be way less than the esc cost!

Also, the turbine power (watts) listed is max power, and there is poor turbine efficiency and gearbox power loss. I suspect that if this 5698 motor is pushed, it can probably get to 45000 rpm/ 7-8000 watts. I read about some castle 2028's reaching 8000+ watts. [/size]My esc and power supply/voltage and motor bearings will not allow that for long!!  And the 5698 is lighter than a 26cc motor and full gas tank Have not weighed my batts yet).   It will put out more power and higher rpms [/size]at 8s and 30v than a tuned 26cc motor.

here is a pic of [/size]Arrow Shark 2015 GX-1 Gear Box for Scale RC Boats.  Arrowshark is made to fit standard 5 in rails, which is nice.  The shafts require gas motor couplings which will work with 1/4 flex shafts.
MHZ also has their own 1 into 2 gearbox, but the arrowshark one looks well made (see website exploded views)
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derekwarner

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Re: XRAD'S HYDROPLANE
« Reply #6 on: January 01, 2016, 11:42:32 PM »

Thanks for the explanation......'That is why you hear the turbine spool up before the props turn' ....

I didn't quite understand this......however makes sense to me now  O0 .....

The gearbox bearings appear to be ZZ, or fully sealed....so does the gearbox breathe  :kiss:,

Most bearings are rated as a B 6 design life......so @ 20K RPM <*<.....would not last without adequate re-lubrication

....... :o.....& I thought my steam plant components were expensive ..............Derek
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #7 on: January 02, 2016, 01:24:40 AM »

Good point. You could replace the bearings with ceramic/other bearings pretty easily. They come in the brushless motors doing 30000+ rpms , so they are out there somewhere.  This gearbox made for ~20000 rpms but with right bearings could easily do 30000. Can;t really do anything about the straight cut gears. But they are hardened, same with the shafts, so they should be OK. And that would be peak rpms, so probably usually running around 25000+. Small amt oil inside, with small filler hole you can see in your pics. The right non-foaming light oil will be key...maybe thinned redline lightweight ATF!
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martno1fan

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Re: XRAD'S HYDROPLANE
« Reply #8 on: January 02, 2016, 07:52:23 AM »

Personally i wouldn't go with twin props on the hydro one would work much better,also you will need a turn fin,hydro's only need to turn at speed one way so whichever way you race that's the side it goes,usually on the right for model boats.At speeds of 60 mph and up the boat simply wont turn without taking flight and flipping over.Hydro's are meant to turn at full tilt,i built  a gas Thunderboat from zippkits a few years ago speed was over 60 mph and fastest i clocked her at on gps was 69 mph and trust me without the turn fin she wouldn't have stayed on the water in the turns.I think if you go the twin rout you will encounter all manner of problems with handling not to mention the gearbox will never hold up to 30k plus rpm. A great prop for most hydros would be a 6717 /3.
Here she is before i added ride pads to the sponsons shes running close to 60 mph here,the ride pads improved speed even more...https://www.youtube.com/watch?v=wVGBWC_3MuY
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martno1fan

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Re: XRAD'S HYDROPLANE
« Reply #9 on: January 02, 2016, 08:27:05 AM »

Heres a similar one to yours doesnt give any info on setup though but it goes quite well...

https://www.youtube.com/watch?v=t_DMO_nK9Cc
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #10 on: January 02, 2016, 09:24:40 PM »

Thx Mart, I have not seen those. Planned to add a turn fin...soon. Will have to cut and reinforce the hull.. but I have not decided if going twin drive or not. Looks like you are running a shovel, don't know what the chines look like under that boat.


Twin props will definitely be better for high speed straight line runs with the hydro body shape, or any hull really.  MHZ also makes a twin drive gearbox which ups the output rpms , and are made for high rpms (~27,500?) but lower input shaft speed...their twin drive box is dual bearing on each shaft . 



I like this one...really flying...then the end....  You can see when he hits the change in the water at the ripple edge.


https://www.youtube.com/watch?v=U32pikSS-yc


I was considering using a servo stabilizer on the front stabilizer, but then more hull cutting...
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #11 on: January 03, 2016, 12:50:27 AM »

OK, first major setback.  Toro beast is not working.   :((     Says "passed inspection" on bottom cover....hmmmm


Started low with a fully charged 4s.  Was able to see the esc on my computer using SkyLINK. actually a nice program which you have to unbox with and .rar decoder ring. I used open knife 7 or something similar.  Double checked all hookups and polarity.  Servo works.


Anyway, hooked up everything .  I was able to set neutral, full th, and full reverse endpoints, and then nothing.  Changed out battery packs, changed out rx and tx. still nothing more than a sputter out of the motor.


anyone else have this issue?
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #12 on: January 03, 2016, 05:24:20 PM »

as a side note, using the same 4s battery, Tx, and Rx with a spare 120A esc, the 5698 motor ran fine in both directions. 
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #13 on: January 03, 2016, 10:44:07 PM »

The guys in RCGroups helped me out.


NO, can't use laptop interface version 2.08 which stinks because it has awesome GUI's.Had to load 1.08 off the toro site which worked fine. Except no motor timing available! Data logging worked fine. I did a cutoff voltage adjust down to 16v, and reload the ESC. then the motor ran fine.


I think the hand held unit allows timing adjust. The 2.08 version is very nice, but have to find a firmware upgrade for the ESC! then load this on my laptop and then load to esc via the 1.08 version, then should work.



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martno1fan

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Re: XRAD'S HYDROPLANE
« Reply #14 on: January 04, 2016, 08:01:14 AM »

On paper you'd think twin drives would offer faster straight line speeds but the reality might be different especially on an rc boat,single drive is def the way to go in my opinion,less headaches.Yes mines a shovel,ride surface is not much if any different from most hydroplanes.Heres a pic of my own design the Comet shes 50",i used the same basic sponson design as the Zippkits with designers permission just slightly larger.The gearboxes you mentioned are mainly aimed at gas engines not electric and i really wouldnt  consider them for fast electric use as i doubt they can handle the rpm,thats my opinion anyway unless someone can show me otherwise . Also better gearbox  in my opinion  is the wd200 gearbox also in Germany but again mainly aimed at gas motors.
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martno1fan

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Re: XRAD'S HYDROPLANE
« Reply #15 on: January 04, 2016, 08:16:31 AM »

On a side note the trick to getting the hydro's to run stable is to keep the nose down so keep weight further forward more so than most other styles of hull.I tended to balance mine 1" forward of the rear of the sponson transoms which seemed to work well,the rest is all about strut positioning and angle of attack but im sure you know most of that already.Have you tried these esc,s ? i have  one its a twin esc for two motors,delivers same voltage to both motors from one source so yes run times will be reduced but im told same voltage to both motors,haven't tried mine yet.Mines from alien but im pretty sure its a re branded product made elsewhere maybe you recognise it.
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #16 on: January 04, 2016, 01:33:51 PM »

Hi Martno, yes I have seen these under several different wraps ('Flier' for example).  Aliexpress has quite a selection.  I usually use MysteryCloud. Only had one bad one out of 5, but they are super cheap. 

Nice hydro!  Mine has a bit deeper chine on the front sponsons as well as carrying this rearward to the transom.  even when '3 point' running, I suspect that the rear of the hull will be dragging on the turns.

Seems that twin drive is the way to go, at least in a straight line.  I am sure that circuit racing hydros will someday adopt it too.

Interesting article:
http://www.toxicrocket.com/docs/Part_2.pdf

Also see the pic, pretty sure that there are two drives...and this is a world record holder "problem child" ~8000 hp !

http://www.highpants.net/top-fuel-drag-boat-problem-child-action-thunder-river/

 
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martno1fan

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Re: XRAD'S HYDROPLANE
« Reply #17 on: January 04, 2016, 02:22:18 PM »

Real boats and rc boats are different animals,single is def what id go for on a  hydro but if your sold on twin drives go for it.
Heres a pic of the Comet,i might yet build one for a single 5692 sss motor on 12 s  :embarrassed: .
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #18 on: January 04, 2016, 10:39:15 PM »

 I just saw a 5670? on offshore electrics. Should make for some high rpm. might be right size for your boat. yes, true, but motor torque and prop walk , although not proportional, still effects our boats.  I did decide to go with single motor singe drive shaft for the moment. I really did not feel like machining another  strut, but I did order extra ceramic bearings and 1/4 shafts just in case I change my mind. 


Unfortunately, the 1/4 teflon tube did not fit into the larger OE plastic tube of the hydro. about .5mm too wide.  Which is OK because the brass tube fit into the OE aluminum tube just fine. So I will just add a bit of silicone sealant between the brass tube and the aluminum tube. this will add waterproofing and take up some of the torque/wave shock. Or maybe I will add some heat shrink to the brass tube and then just a touch of silicone where the brass tube exits the hull.... I do like the OE design of a plastic tube, which at original design speed of 35-45?mph would work well. But I think it would flex all over slamming the water at speeds greater than 50 mph.  It would be great if I could get a stinger back there...

Bought some 1/4 drive shafts off ebay from Niagara falls dealer. VERY nicely ground , nice teflon tube, and thin grease. Not the smelly cheap machine grease like the OE. Also the flex cable is very smooth and even. Will just cut and braze up the end once I find correct length.
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martno1fan

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Re: XRAD'S HYDROPLANE
« Reply #19 on: January 06, 2016, 07:17:23 AM »

Prop walk wasn't an issue on my hydro maybe the fin helped that im not sure ,what i do know is some fins work better than others .

What i always do with tubes with liners is a use shoe glue to glue them into the tube so they will never spin inside the tube which is why many over heat and fail . Wondering why you made the strut and not just buy one .

I run my brass tube right into the back of the strut,if using a liner and the tube doesn't fit been wider then just leave some Teflon sticking out the end and slide that into it  :-)) .
Mart
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #20 on: January 06, 2016, 01:20:57 PM »

in post #1: 

'I will have to machine a strut to carry the stainless 1/4 id bearings for the 1/4 flex shaft.'

I can always buy a strut with brass insert. wanted to try ceramic/stainless bearings. plus the fun of making one......
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Tombsy

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Re: XRAD'S HYDROPLANE
« Reply #21 on: January 06, 2016, 05:46:17 PM »

A slight S bend in your flex shaft is supposed to control cable whip better and have less parasitic drag. But it does make replacing the flex tube harder not that I've ever had to replace one. It also gives you a better angle to keep the motor lower for a better COG.
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #22 on: January 06, 2016, 06:55:34 PM »

Interesting, thx for tip.  So you mean a curve down inside the hull opposite the up curve under the boat?   I might try this....

I have to say the 1/4 flex cable I just got is really smooth.  There is minimal play side to side inside the flex tube, and yet the cable has about zero resistance and wants to shoot out the other side if I hold it on the least bit of an angle. The OE cable and tube offered a moderate amount of resistance when I try to remove the cable and it was not easy to turn. 

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Tombsy

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Re: XRAD'S HYDROPLANE
« Reply #23 on: January 06, 2016, 07:45:36 PM »

Yes exactly a slight curve down inside the boat, gives you a slight s when viewed from the side. I don't use Teflon liners on 1/4" flex, I use 5/16" brass nested inside the next size up which gets epoxied in. Then if you ever have to change it you stick a soldering iron in the end to melt the epoxy.
I've seen those Teflon liners wind up inside the brass on the higher power boats. (.67 nitro) I do use them on some 3/16" flex.
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xrad

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Re: XRAD'S HYDROPLANE
« Reply #24 on: January 07, 2016, 12:25:37 AM »

ok got it thx.   I will consider this when building the drive system.  Here are a few pics of the strut. flanged rear Ceramic/ss bearings arrived.   Strut drilled three 4 times. First a 1/4 center, then 1/4 through drill, then 21/64 through drill, then 3/8 in about 1/2 inch from the rear and about 1.25 inch from the front. Center ridge keeps rear bearing in place.   The second pic shows my fast way of reverse centering for the 3/8 drilling into front of strut. The 21/64th bit is put through the strut from the front, and then mill lowered and strut clamped in vise (probably would have bee easier to clamp the vise to the strut and then clamp the vise down to bed, but either way allows for slight deflection). not 100% accurate, but will work for this build. brass tube fits nicely into front of strut, but smaller than 3/8 by about 10 thou.  The 3/8 bearings fit fine and leave plenty of room on the outside for strut strength (1/2 thick). Also, 1/4 stainless axial bearing (boca) between dog and strut, and another axial bearing (8mm) between clamp and motor housing. So that should do it for bearings.... will see how they hold up.
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