Model Boat Mayhem
Mess Deck: General Section => Model Boating => Topic started by: warrior193 on March 07, 2010, 04:56:49 pm
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Hi, i'm a new member to the forum - considering getting a large (46") kit of the Huntsman 31 with the GRP hull. The supplier recommends powering with 12 volt gell-cell feeding a single torpedo 850 motor. I have seen some old posts from 2008-09 suggesting that this is not the best power route. From experience in full-size boating, I would agree with the single big motor rather than two smaller ones (less drag, weight, expense, etc) I see that a number of forum members suggest going brushless - which I like the sound of. I'm assuming that going brushless will require something better that the gell-cell? would cyclone D cells work - or will I have to go full LiPo packs? My aim is to get a good fast plane (a bit more than scale speed, without going completely mad) and run times of 20-30Min's, is this reasonable? I realise that waterproofing these high power electrics is CRITICAL, as are the power cable lengths but I guess other modelers have achieved success with projects similar to this. :D
Any comments welcomed.
warrior193
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have a look at these two, plenty of ideas also if you do a search for " Huntsman" you will find some more, also read what has been said about the kit you are about to buy first.
peter
http://www.modelboatmayhem.co.uk/forum/index.php?topic=21019.0
http://www.modelboatmayhem.co.uk/forum/index.php?topic=21584.msg221995#msg221995
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Waterproofing isn't as critical as you'd think, a fast electric boat got a good dunking down our club a week ago (hatch off, boat nearly sinking) but it still ran again this thursday. I have a large huntsman that's yours if you're ever in the area, needs a little work doing and its a wood hull...
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Gel cell - avoid at all costs. Far too heavy and not enough grunt to supply heavy currents.
850. Avoid. Electrically noisy, crude and current-hungry.
For a single brushed motor, either MMB900 on direct drive or a planetary-geared Darke Horse 785, both on 20 cells with 50mm 3-blade prop or 55mm 2-blade. NiMH cells are good. No experience of LiPos.
Brushless - no personal knowledge, but it's already been done by a Forum member.
FLJ
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Gel cell - avoid at all costs. Far too heavy and not enough grunt to supply heavy currents.
850. Avoid. Electrically noisy, crude and current-hungry.
For a single brushed motor, either MMB900 on direct drive or a planetary-geared Darke Horse 785, both on 20 cells with 50mm 3-blade prop or 55mm 2-blade. NiMH cells are good. No experience of LiPos.
Brushless - no personal knowledge, but it's already been done by a Forum member.
Hi FLJ
Thanks for your reply, I understand from other postings by you, that you had a hand in the design of the Huntsman 31 kit - can you tell me if the precedent kit gives the option of the open cockpit version? as I prefer this to the aft cabin. Do you know of a better kit maker for this classic? O0
Regards, warrior193.
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Thanks for your reply, I understand from other postings by you, that you had a hand in the design of the Huntsman 31 kit - can you tell me if the precedent kit gives the option of the open cockpit version? as I prefer this to the aft cabin. Do you know of a better kit maker for this classic? O0
Regards, warrior193.
Yes - both hands, actually.
No it doesn't. You'd have to modify it yourself.
No other kits for the 31 as far as I know.
FLJ
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Thanks for your reply, I understand from other postings by you, that you had a hand in the design of the Huntsman 31 kit - can you tell me if the precedent kit gives the option of the open cockpit version? as I prefer this to the aft cabin. Do you know of a better kit maker for this classic? O0
Regards, warrior193.
was it the timber or the fiberglass Huntsman you wanted ?
peter
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was it the timber or the fiberglass Huntsman you wanted ?
peter
Hi Peter, I'm a little lazy and not a fantastic carpenter (although I have built a couple of full-size boats) - so am inclined towards the GRP hull for a easy start on the basic build! Can anyone tell me the name of the resident BL expert, I would like to try this power route (possibly outrunner?) and am seeing some reasonably priced motors in this field - the obvious problem being only able to water-cool one end plate. I am tending towards a relatively large motor and limiting the top end, keeping the heat down. What is the current preference between inrunners / outrunners in the marine world? :P O0 {:-{.
warrior193.
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I would like to try this power route (possibly outrunner?) and am seeing some reasonably priced motors in this field - the obvious problem being only able to water-cool one end plate. I am tending towards a relatively large motor and limiting the top end, keeping the heat down. What is the current preference between inrunners / outrunners in the marine world?
Warrior
Have you read through the two threads that HS93 posted above?
Phil.
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Hi Phil, yes I have been through them fairly thoroughly? - but I still don't see comparisons between in or outrunners in marine BL. I can see that inrunners would be more similar to brushed motors - and easier to water-cool - but is the extra performance available from outrunners worth going this route? I'm thinking - single big outrunner; fairly low KV (750-1200 area) fairly big 2 blade prop and possibly LiPos. I didn't see what size and make of motor you used - it looks like an inrunner though and I saw that you did move the prop shaft - was the original set up nonstandard (it looked very different from other boats of this type)
Regards, Brendon (warrior193)
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Waterproofing isn't as critical as you'd think, a fast electric boat got a good dunking down our club a week ago (hatch off, boat nearly sinking) but it still ran again this thursday. I have a large huntsman that's yours if you're ever in the area, needs a little work doing and its a wood hull...
Hmm, that sounds tempting - at least that would avoid the niggling faults in the original kit ;D Is she in the 1/8th scale and what are you asking for it?
Regards, Brendon (warrior193)
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It's the 46" kit, all wood and if you want it, it's yours. I'm afraid you'd have to pick it up though.
Does need a bit of work doing to it, but much less than buying the kit new.
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Hi Warrior
My experience of brushless motors in boats is very limited although I do have a fair bit of experience with BL motors in aircraft. My Huntsman is the 34" version so it's quite a bit smaller than the one you proposing to build so I cannot reccomend an exact motor to try. The motor in my Huntsman came from Giant Cod, it's an out runner of 900Kv and 35mm diameter, it gives far more power than the model can handle at very low currents, the highest yet recorded is 22A at this level the hull was coming out of the water! After a run of about 15 minutes the motor and speed controller were slightly warm to touch so I will not be bothering with water cooling.
As for choosing a motor a lot of internet shops give motor power equivalents to a glow engine. My gut feeling is something like this motor http://www.giantcod.co.uk/xyh4250-700kv-outrunner-p-404600.html (http://www.giantcod.co.uk/xyh4250-700kv-outrunner-p-404600.html) would give more than ample power (quoted at 720 watts) and should drive the boat around at high speeds without even getting warm. Cheap too. By the way this is the bigger version of the motor I'm using in my Huntsman.
With regards to the propshaft I don't know if the original one was non standard as I don't have the plan for the model (I didn't build it either) But the new shaft is at a more sensible angle.
Phil.
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Hi Phil, thanks for the info - very helpful, I was looking at Giantcod last night and they seem to have what might work well - it's good to hear that the quality is good, as I was thinking the prices were too good to be true. Am I right to think that the design of the outrunner "pumps" air through the motor as it rotates, and are the standard mounts easy to adapt to marine use?
Regards, Brendon. O0
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That giantcod one would be far too small, thats the size I would put in a small Huntsman, maybe bigger even.
As a wild guess, I'd suggest a 600 size heli motor. The 46" Huntsman was designed for a .60 sized engine with power getting towards a kilowatt. I was going to use a 23cc petrol in mine that has 3.6hp.
http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=7242&Product_Name=KD_600XL_1100kv_Brushless_heli_Outrunner_/_1600W
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Am I right to think that the design of the outrunner "pumps" air through the motor as it rotates, and are the standard mounts easy to adapt to marine use?
Brendon, Not sure that air is pumped through the motor but the casing does seem to promote air flow through the case. I think the thing with the out runner that I'm using is thats it's pulling so little power from the battery that it's just not getting hot, these brushless are very efficient that is to say that much more power is used to rotate the motor than is used to make heat. Unlike a brushed motor that makes a very good heater :o
To mount the motor I fabricated some simple brackets from ply with some copper clad board to screw the motor to. I will try and post some photos later.
Thats a mean looking motor that Andyn has linked to, quoted at 1600 Watts peak power :o :o Not sure you need that much power but then I've never built a boat that big.
Phil.
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That giantcod one would be far too small, thats the size I would put in a small Huntsman, maybe bigger even.
As a wild guess, I'd suggest a 600 size heli motor. The 46" Huntsman was designed for a .60 sized engine with power getting towards a kilowatt. I was going to use a 23cc petrol in mine that has 3.6hp.
http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=7242&Product_Name=KD_600XL_1100kv_Brushless_heli_Outrunner_/_1600W
Holy moley, the Huntsman would fly with that - I think it would almost go WIG with this much power, then how would I keep the prop in the water? {-) Are you sure that 2 HP is really required? :o
Regards, Brendon.
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I think you will find this is one of the 600xl motors in red181s boat
http://www.youtube.com/user/pmdevlin1
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Holy moley, the Huntsman would fly with that - I think it would almost go WIG with this much power, then how would I keep the prop in the water? {-) Are you sure that 2 HP is really required? :o
Regards, Brendon.
I have seen the 48 inch Perkasa MTB on a single MMB 900 running on youtube - speed seems pretty good for that model (although I can only guess at the weight) Am I correct that I am looking at approx 30% more power with the Giantcod XYH42-50 brushless outrunner (with a much lighter motor) -compared with the 900? I would like to keep the ESC reasonably affordable :D
Regards, Brendon.
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I think you will find this is one of the 600xl motors in red181s boat
http://www.youtube.com/user/pmdevlin1
Cripes - OK, I'm convinced %% %% -way over scale speed but hull looks able to cope ok. Is this the 1/8th scale version? I'm guessing that even in the sprints she's not WOT!
Brendon.
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its still not proped right if you look at the size of the lake you cannot get a run so he played acceleration , bigger prop will help top end as you will notice it hits full revs very quick, he also wants to up the batteries, the motor is still cool when running.
Peter
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Thanks Peter, I have a slight concern with some of the comments re loose magnets with this motor - is that still an issue with this make, or is a easy fix/mod? I have been attempting to find a similar size to the 600XL in the Giantcod XYH series, as this make looks very inexpensive and bullet proof to boot - still looking but starting to go cross-eyed with all the the data sheets. %%
Brendon.
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he is using the Align 600l second hand off ebay, the cost of the motor unfortunately low compaired with buying a good bullet proof esc.
http://www.align.com.tw/shop/index.php?cPath=22_67&language=en
have a look at post 27 onwards to get an idea
http://www.modelboatmayhem.co.uk/forum/index.php?topic=21584.0
Pm him if he does not come on and comment.
Peter
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The early ones had loose magnet troubles but I think it's fixed now.
When you get it, take it apart (easy to do) and give them a good wiggle.
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Andyn will prob know my motor looking at his avatar! Its an align 500 heli motor, 1620kv (if my memory is right), thanks HS93 for posting info.
Unfortunately, brushless info on a large scale boat like this is non existant. We spent a long time trawling loads of forums for info, and it all came down to trial and error. I can confirn that water cooled on 6 cells (most recent video) all was very mildly warm, but, I couldnt get a long run in, lake was too small, and it was a very cold day.
The problems with brushless start when the motor stops, and the water cooling stops, they dissipate heat at the front, so we are going to have to make a water cooled motor mount, or at least have a water cooling pump system when boat has stopped to cool the motor. Last time out, when stopped, 5 mins later motor was hotter then when running.
An out runner could cause problems, as you will not be able to run a water jacket or cooling coil on it, and there is always the danger of something getting fouled in the very fast spinning can. I also use a 2:1 gear ratio, 50 mm 2 blade prop, about to fit a modified 52.5mm prop. Standard 52.5mm was too much load, so I have trimmmed the trailing edge of the blades which will lessen the load, but keep the larger dimemsion, I hope! :embarrassed:
Unfortunately, the answers will not come from this forum as its not really been done, its easy to guess or estimate what performance will be like, but seeing it in operation is the only proof, Ive said it before though, the lipos are a pain, need looking after too much and are a bit of a worry, exactly the same problem is happening with a small brushless jetboat project we are toying with.
With regard to the models, 31 is the aft cabin, mine is the 28, Huntress is shorter than the 28 (Made famous by James Bond in From Russia With Love), google fairey owner club, loads of info and nice pics there, I got most of my cosmetic info here :-))
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You say six cells, is that 6s Li-pos?
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yes 6s Li-pos? and he runs 24v Nimhs
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Andyn will prob know my motor looking at his avatar! Its an align 500 heli motor, 1620kv (if my memory is right), thanks HS93 for posting info.
Unfortunately, brushless info on a large scale boat like this is non existant. We spent a long time trawling loads of forums for info, and it all came down to trial and error. I can confirn that water cooled on 6 cells (most recent video) all was very mildly warm, but, I couldnt get a long run in, lake was too small, and it was a very cold day.
Hi RED181, thanks for your comments, I assume that you still consider outrunners are the way to go - even with the cooling issues, would installing a small computer PSU cooling fan help on motor shut-down? just a thought :embarrassed:. What is the length and displacement of your 28? Without going for the absolute "manic" speed %% that your boat is capable of, do you still consider that a .30 glow equivalent BL motor(about 1000Watts, low KV) in the 46 Huntsman would be too small for a reasonable plane?
Regards, Brendon (warrior193) :-))
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The original 46" Huntsman 31 had an HP 61F R/C 2-stroke glowplug motor. This was the first 1 HP model motor. 1 HP is about 735 Watts, so your 1000W brushless motor should - in theory - be enough, as long as you match it to the correct prop and don't load the model down with too much battery weight.
FLJ
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its a real tough question warrior, after the motor, the prop and shaft angle play a big part. Mine is 42" or there abouts (I think!, cant get at it at the moment), with 2 x 3 cell lipo packs, all up ready to run with the batteries for the cabin/nav lights, its a little over 6kg, so quite heavy, but this hull likes to be thrashed so when its up and running its great. There have been a couple of builds recently that have had handling problems, which up to now are unresolved, hopefully we will be kept informed about the progress.
regarding outrunners, in theory they should run cooler due to the nature of operation, I considered a fan myself, but its extra battery drain, or another independent power source adding to weight. 1000kv "should" be enough, it will have loads of torque, so if the boat is heavy it will work, but may not deliver the top speed. Are you planning direct drive or gearbox, as this too will effect performance and run time. :-))
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The original 46" Huntsman 31 had an HP 61F R/C 2-stroke glowplug motor. This was the first 1 HP model motor. 1 HP is about 735 Watts, so your 1000W brushless motor should - in theory - be enough, as long as you match it to the correct prop and don't load the model down with too much battery weight.
FLJ
Hey FLJ, thanks for your help and advice - That helps a huge amount in arriving at a workable motor/ ESC size without breaking the bank. I'm sure to blow a few things at the start - so keeping cost of disasters down will be great :-)) Maybe later on I will go for WIG type power as per Paul's 28. %% %% %%
Regards, Brendon
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its a real tough question warrior, after the motor, the prop and shaft angle play a big part. Mine is 42" or there abouts (I think!, cant get at it at the moment), with 2 x 3 cell lipo packs, all up ready to run with the batteries for the cabin/nav lights, its a little over 6kg, so quite heavy, but this hull likes to be thrashed so when its up and running its great. There have been a couple of builds recently that have had handling problems, which up to now are unresolved, hopefully we will be kept informed about the progress.
regarding outrunners, in theory they should run cooler due to the nature of operation, I considered a fan myself, but its extra battery drain, or another independent power source adding to weight. 1000kv "should" be enough, it will have loads of torque, so if the boat is heavy it will work, but may not deliver the top speed. Are you planning direct drive or gearbox, as this too will effect performance and run time. :-))
Hi Paul, thanks for the tips, I was thinking direct drive with a fairly low KV / speed outrunner - was aiming for around 1000KV and between 700-1000 Watts. Will obviously have to play with props though - may eventually have to get "specials" made. Re the cooling fan, my thought was to use thermistor on end plate - fan would probably not be required during normal running, but would cut in when motor shuts down or as required. I don't think that these fans draw too many amps anyway, I will add it to my research list - although it may not be too much of an issue with the motor I am thinking of using :D
Regards, Brendon (warrior193)
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hmmm...we need someone who can explain this, maybe HS93. I have 1620kv motor. When it ran on 1.5:1 ratio, things got hot. That was with 52.5mm prop. Changed ratio to 2:1, everything nice and cool. Didnt have a gps, so cant comment on speed difference, but visually didnt seem much.
1.5:1 ratio, with a different prop, which was a real nice ally racing prop, big pitch, 50mm, everything blew up, but for a few seconds, it was ballistic, much faster than all the video I have posted on my build thread, so it was too much. After every slight tweek, I always seem to end up with 2:1 ratio, 50mm prop, but it sounds like its overrevving a bit. Just finished modifying another 52.5mm "x" prop. I have taken 1mm off each trailing edge, flattened and polished the prop, even though its plastic, the theory being it can handle 52.5mm, but with less blade area, thus less load, jury out till it runs!
Now, if you are going to run 1000kv direct drive, your prop will be spinning faster than mine without a reducing gearbox, so in theory will need a smaller prop, if everything else was equal. I would advise starting 2 blade 45mm "x" ("s" props where useless in all my testing) and graduallly work up in size, remember brushless motor heats up after a run, and monitor esc and battery temps. I think direct drive or 1:1 ratio as it will be might shorten the run time, will be interesting to see ok2
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Hi Paul, you're up late too, just been looking on Giantcod again, and I am now looking at a .45-.60 glow equivalent outrunner rated at +900 Watts at 650KV - that may address the higher revs and allow me to swing a bigger prop or more pitch, I will start out on the small size and work up. I may try NiMh cells to start with before going to the riskier LiPos {:-{. I understand that the lower KV motors have quite a lot more torque- is that generally correct? Still looking for suitable (cheap! reliable? mission impossible??) ESC. I have an offer of a 46" Huntsman from another forum member, and I will allow for bigger props on the new shaft angle if necessary O0
Regards, Brendon.
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Brendon
Thats right, the lower the Kv the more torque but make sure you can get a prop big enough to use up all that power with enough pitch speed.
How about this motor at an eye watering 7Kw http://www.giantcod.co.uk/xyh80100a-180kv-brushless-outrunner-7055-p-404968.html (http://www.giantcod.co.uk/xyh80100a-180kv-brushless-outrunner-7055-p-404968.html)
Phil.
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Hi Phil, not sure I could fit a big enough tough prop under the hull with that one %% the leads from the power station might get in the way too :o seriously though, 100 Amps isn't as high as I thought would be the case with this size motor - these seem to be much kinder on the Amps as you go down in KV rating - the motor I'm seriously considering for the Huntsman is from the same range, just a little smaller :} Is anyone reading this using XYH series outrunners - comments on quality would be welcome (although at the price, probably worth a gamble) - now to source a suitable ESC <*<
Regards, Brendon
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Brendon
I'm using a XYH35-48 900Kv in my 34" Huntsman like this one http://www.giantcod.co.uk/xyh3548-900kv-brushless-outrunner-p-402745.html (http://www.giantcod.co.uk/xyh3548-900kv-brushless-outrunner-p-402745.html) Good quality, plenty of power and only £16, recommended :-))
Phil.
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Hi Phil, I was looking at that one - but am now inclined towards the XYH42-60/600KV with 900 Watts available. This should enable me to swing a fairly big prop, only issue is revs may be a bit low {:-{ Going on comments from Paul (red181) I might get away with using up to 55mm prop - but will start smaller dia. as advised by just about everyone (don't want to let the magic smoke escape ;)) Can you recommend a reasonable priced, tried / tested ESC for the 42-60? - 45 Amps max; 38 Amps Max efficiency, 900 Watts; 600KV - rated for 3-7 LiPos? I understand that these motors are some kind of Thurnigy clone, how do find the quality of them? PS. I will be powering Andys old wooden 46 Huntsman.
Regards, Brendon.
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Brendon
I'm using a Giant Cod 60A opto esc like this one http://www.giantcod.co.uk/speed-controller-opto-p-402445.html (http://www.giantcod.co.uk/speed-controller-opto-p-402445.html) No water cooling or reverse but it works well and runs cool.
How many volts do you plan to run on?
Phil.
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Hi Phil thanks for that, with the opto type you don't get reverse - is that correct? Is there more protection in an opto isolated ESC? With the size motor I'm looking to use I think I may be better to go water-cooled - what do you think? I'm inclined to go for 18-22Volt batt pack (may try NiMh before going full on LiPos (they do scare me a bit with all the horror stories :embarrassed:. For safety, would I be better to look at an 80Amp ESC, fused for 60Amps (as FLC should be less than 50 Amps unless I stall it :D) or do you think I need to go higher Amps? I'm not sure about being able to manage without reverse though :embarrassed:
Regards, Brendon.
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I helped Paul out on the Huntsman i had got hold of a couple of cheap controllers and was not happy with them ( the same as the Giant cod ones) they are a pain to use as you have to arm them every time you turn on, and the program card are useless. I got a couple of http://www.castlecreations.com/ and Paul tried one in his the difference is amazing set it up in seconds very smooth in operation and can be repaired for a reasonable cost as opposed to bining it. they have a very good guarantee as well no problem getting a replacement plus true amp ratings.
http://www.castlecreations.com/products/hydra.html
peter
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Hi Peter, thanks for that - regarding the GiantCod ESCs that you were not happy with, were these the SPs or the SeaKing 60 Marine?
Regards, Brendon.
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Not had any problem with my cheapo GC SP esc, they start every time. The opto part is just to isolate the receiver from the esc noise and the receiver is powered by a seperate SBEC connected to the motor battery pack. Reverse is a function of a marine esc but as I only want shoot around the lake forwards I'm not to worried about reverse. Don't believe all the scare stories about Lipos, used correctly with a good charger they are safe and much better than round cells.
Phil.
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Hi Peter, thanks for that - regarding the GiantCod ESCs that you were not happy with, were these the SPs or the SeaKing 60 Marine?
Regards, Brendon.
Hi mine where the Turborix version, they all seem to come out of the same factory and are just badged with stickey labels.
Peter
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Not had any problem with my cheapo GC SP esc, they start every time. The opto part is just to isolate the receiver from the esc noise and the receiver is powered by a seperate SBEC connected to the motor battery pack. Reverse is a function of a marine esc but as I only want shoot around the lake forwards I'm not to worried about reverse. Don't believe all the scare stories about Lipos, used correctly with a good charger they are safe and much better than round cells.
Phil.
Thanks Phil, that helps a lot - I have seen some water-cooled (marine) ESCs with no reverse, as you say, racers don't need reverse %% - so thats motor and ESC shortlisted :} - now just to get brave on the batts :-)) I can see that I will be calling on Andy sooner than I anticipated, to take him up on his kind offer of a hull :embarrassed:
Regards, Brendon.
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Thanks Phil, that helps a lot - I have seen some water-cooled (marine) ESCs with no reverse, as you say, racers don't need reverse %% - so thats motor and ESC shortlisted :} - now just to get brave on the batts :-)) I can see that I will be calling on Andy sooner than I anticipated, to take him up on his kind offer of a hull :embarrassed:
Regards, Brendon.
Hi again Phil / anyone - one more silly question :embarrassed: regarding LiPos - is it safe to series up multiples of similar size packs to increase the total voltage, and also to parallel packs up ditto to increase the amp hour rating? Thanks also to Peter for the picture and info on ESCs. :-))
Regards, Brendon.
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Brendon
Not a silly question, my teacher taught me that the only silly question is the on you don't ask :-)) Not an easy answer though. Yes you can parallel or series the packs but, the more you join the packs together the more difficult to manage. You should charge each pack separately balancing as you charge. Large capacity packs are available for reasonable prices now again check out Giant Cod for Loong Max Lipos, good value. But you do need to invest in a good charger though that will handle the packs in larger sizes than you expect to use.
Got to go now.
Phil.
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Great, thanks for that Phil - as it happens, I was looking at the Loong max Lipos :-)) :-)) - just waiting for an answer {:-{ from Rob at RC supplies about battery capacity on the SeaKing 60 Amp ESC - I gather that the V2 version of this unit can handle up to 6S LiPos, but I'm not sure that this is the version they are shipping.
Regards, Brendon.
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Great, thanks for that Phil - as it happens, I was looking at the Loong max Lipos :-)) :-)) - just waiting for an answer {:-{ from Rob at RC supplies about battery capacity on the SeaKing 60 Amp ESC - I gather that the V2 version of this unit can handle up to 6S LiPos, but I'm not sure that this is the version they are shipping.
Regards, Brendon.
Thanks to all you guys for the help and advice - especial mention to ANDYN for his fantastic offer :-)) and to FLJ, Flying Sparks, Red181 and HS93 for the benefit of their experience in keeping the magic smoke in :D I have now got a pretty fair idea of what will probably work well - will keep you posted as the Huntsman project progresses - awaiting stock on motor, and planning a visit to Andy soon :-)) One more question - does anyone know of a supplier for watercooled motor mounts (end plate) that would fit a XYH 42-60 outrunner? belt and braces - thats me :}
Regards, Brendon (warrior193)
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I think FLJ put a link on the other day of a new company that did them. when you build your boat two things build light and build even lighter, that is worth more than fast motor.
found it
http://www.modelboatbits.com/index.php?p=1_108
Peter
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Thanks for the link Peter - and the price keeps climbing {-) I will keep in mind your comments re weight - I do have the contingency to go up in size on the motor if necessary %% but that will probably mean more batteries :o. I'm inclined to experiment with NiMh cells to start with (taking the weight penalty) with the knowledge that if the performance is a little too sluggard, changing up to LiPos will probably cure that <*<. My intention for the project is not for a blur on the water (the yachties on my home water might not thank me for that! >>:-(), but I'm hoping for a good fast plane :}
Regards, Brendon
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Hi Brendon, well it was a wild ride last sunday evening, and nothing blew up, but its going the right way! 6 lipos cells, which for reference are 2 x Turnigy 5000mah 30c (which I dont think is enough now, ) bought from hobbyking, so to answer your question, they are wired to give 22.2v. I wouldn't wire to double the mah, if one pack discharges quicker than the other, it can drain the other pack, or act as though its charging it, I am sure someone else will come along to explain it better, but its not recommended.
I changed from 50mm prop in earlier video, to a modified (still plastic "x" prop) 52.5mm. Previously, the 52.5mm was too much load, and things got hot, this time I had removed approx 1mm from each blade trailing edge, painted and polished it, and the increase in speed was very noticeable, with no extra heat. Next is a nice ally "x" prop, as I think there is too much torque now for the plastic one and the blades are bending.
I am now getting some sort of "torque roll", the boat wants to rotate in the opposite direction to the prop! you can see this on the video, and.. i got it airbourne, but only briefly! :}
I have loaded up another video on my build thread, unfortunately it doesnt look much quicker, and the young cameraman struggled keepng up at times, so apologies for duplication, but it was a bit scarey, time for a bigger lake..... :-))
(http://i238.photobucket.com/albums/ff100/pmdevlin/th_hunts525mmprop.jpg) (http://s238.photobucket.com/albums/ff100/pmdevlin/?action=view¤t=hunts525mmprop.flv)
for some reason, the quality of video seems to be getting worse and worse!!
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:-)) :-)) %% Paul, thanks for the video, that speed looks pretty good to me - I will be ecstatic if I get close to that O0. I calculate that you have just under 18000 rpm unloaded at the shaft, where my 600KV on direct drive should give me just under 13500 rpm - I may even be looking at a 55mm prop. Am I correct in assuming that you are running a L/H prop, did you get similar torque reaction on the smaller prop, and is the motor can spinning the same direction as the prop? my guess is the sheer torque of the outrunner (if it is spinning anticlockwise) is throwing her over onto her starboard chine - a single prop will do this to an extent on boats anyway - hence counter-rotating props on twins, she looks to be heeling most on hard acceleration. Would a small trim tab / flap / wedge on the starboard side help? She should be fine on clockwise circuits though - but scary on fast left-handers ;D Your input is fantastic, please keep me posted.
Regards, Brendon.
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I would have thought with a 55 mm prop you would not need a smoke unit for your boat, far to big start with 45mm I would have thought..
Peter
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Hi Peter, yes I have been taking note of the advice regarding starting small and working up - although just looking at Paul's data and with my proposed low KV motor, I suspect that even on direct drive my torque figures should be at least as high than his? (has anyone else used a low revver?) -and will end up with something over 52mm dia - I guess it depends on whether I can get the correct pitch (I gather that there is not much choice unless you go to custom props) it will be interesting experimenting <*<. I must ask Paul if he knows what revs/Amps he is pulling on his modified 52.5mm prop.
warrior193.
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Hi Brenon, unfortunately all recent tests have been without any data logging, so its guesswork regarding amp draw and revs, I need HS93 with me for that (hint hint!), but its been so cold till recently its been touch and go regarding any testing, very much a last minute dash out so couldnt arrange proper testing with data logging, I think the results will be interesting.
With the smaller prop I didnt happen, and with larger prop on 5 cells it didnt happen, this was the first time, and the fastest speed. HS93 has suggested a trim tab also, but I will wait to do anything till everything is decided on setup.
Looking from rear, prop turns antoclockwise, the motor faces the bow, so its also turning anticlockwise. I now need a long straight run, and then can see if the boat is actually turning when running, or just leaning. On the small lake you dont really get a true straight run, the banks close in very fast! :}
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Great stuff, it sounds as you might be getting closer to max power output for the motor/prop with the 6S LiPos. Just a thought, is there a reduction gearbox available that reverses the direction of rotation, IE - motor turns clockwise, shaft turns anticlockwise - and would this then tend to cancel out the torque reaction (if that's what it is)? This might be one disadvantage of outrunners - with the mass of the big magnets rotating with the can becoming a very big gyroscope. I seem to remember hearing of a phenomena like this on big rotary aero engines. It will be interesting to see log data %%
Regards, Brendon.
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you can do the gear box eather way, we did this one this way to get the weight where it was on the original boat.Paul has been testing when the water was just above freezing and at one time the lake was partly frozen, the lake is very open to the sea so can be very cold there, I am in a chair so get very cold quick, so does Paul when he has to fish tools out of the lake. you need good weather for testing as you don't get the best out of your cells at these temperature's and logging data, bringing in swapping something sending it out etc you tend to rush if its cold or wet, I have some new test equipment in the making that should help a lot. it's temperature that is the main thing to keep checking as you don't get a second chance with some of this stuff.Paul may come back with a picture of his fire boat that has a reverse motor set up.
Peter
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Hi Peter,Andy and Paul - well I'm back from Pennsylvania and keen to start on the Huntsman project, have been spending %%, after considering the advice from you guys. I have decided to go for a Turnigy 42-60, 600 KV outrunner, running off two 3S, 5000m/ah LiPos in series. I already have a Seaking 60 amp ESC (hope that keeps in the magic smoke :D) and have ordered the motor from Hong Kong as the Cod are out of stock again - Rob must be a very busy man!. Andy, does your offer still stand? ;D. My wife is now probably not attending the Malvern show, so I am just itching to get started on the hull - would it be OK to call on you, perhaps in the next few days? I will send you a private message and get your postcode. By the way, does anyone know if there is a central booking scheme for Wicksteed, or do you just book with the venue?
Regards, Brendon (warrior193)
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Yep my offer still stands, need the space in the loft :-)) Call me anytime after 12pm.
For Wiki park, you just turn up. If you want to do some camping with the rest of us you need a permit from the park itself, mention us on the phone.
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Hi Brendan, I have just had some amp readings when running 6 cells over on my build thread, youi might find them informative as I have used the 55mm prop you where thinking of. Run time suffers, but its a wild 10 mins!Any progress with your build?
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Hi Paul, great to hear that the 55mm prop works - will have a look at the Amps later. I picked up the hull from Andy a couple of weeks ago, and have done stripping out of redundant gear only - have been a bit busy doing a some work at my Mother-in Laws old place down the road (she passed away last September, and tenants move in mid-May. I may leave the prop-shaft where it is for the moment (shaft angle of old IC installation looks OK?) - although motor will be right forward (C of G may be an issue) Still awaiting delivery of motor and batteries from Hong Kong (Thurnigy 42-60 and 5000M/ah Lipos). Could you let me know the distance between your prop and the transom, and ditto the distance of the rudder? I am still undecided as to cutting her down to the open cockpit version, as I don't really want to cut away the rear deck and bulkheads (the rudder position for the open version looks to be further aft) I need to replace the spray rails on the bottom (3 per side, running parallel to keel) - do yours have a special profile, or are they just square strips? If I extract digit I may have her sort of running for Wicksteed along with the 1 Meter and the Gaff Schooner
Regards, Brendon.
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(http://s3.postimage.org/6vu4r.jpg) (http://www.postimage.org/image.php?v=Pq6vu4r)
Hi Brendon, here are the measurements, but I didnt build the boat new, so dont know if its right. I have a set of original Veron plans, and it looks the same. The rudder was on it, probably not original, but never changed it as up to now it works, but I do now suffer from prop torque on right handed turns, fast left handers are a dream! This position of prop and rudder is very similar to the real boat. The 3 strips are an unusual profile, I had never noticed before, and when refurbing I paid little attention to these, I didnt know what an important feature they where to handing characteristics. They run straight, and do not curve to a point at bow. THe boat was originally painted in a thick paint, and was almost impossible to get off the hull due to the rails, so I have probably damaged them, also we reset the angle of the shaft, it was in the same place, but at a very big angle, the thought was that at speed it would not push the boat along, more push upwards, and now with a 55mm prop there is very little gap between the blade tips and hull, so no waste of propulsion.
Hope that helps,
Paul
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Thanks very much for that Paul, that's very helpful, time to start practising my wood butchery <*<. I must study your previous photos for where your motor is located. Regarding your prop clearance - you may be getting a little too close to the hull for max efficiency - the convention for full scale boats is to aim for a minimum hull to prop clearance of approx 10% (or more) of prop radius - IE. 2.3mm for a 55mm prop. I was not able to find a recommended maximum clearance though (this may not be a particularly important factor - hope not as mine has at least 52mm clearance between shaft and hull) There is no way that my 900Watt motor will swing an 90mm prop {-) I know that scaling down something does tend to change the results from full-scale though. Your solution may be to go for a smaller prop with more pitch if you can get one.
Regards, Brendon.
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I agree, I think its time for a decent 3 blader, I had a vast improvement when I changed my Aerokits fireboat from plastic "x" to 3 blade cleaver prop, less amps, and more speed, it is a prop shop one.excellent quality
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Hi Paul, the convention on fast rigs is fewer blades is better (apparently - a single blade is ideal, apart from the obvious issue of balance) {-) this is where surface piercing drives come into their own - the upper blade in a conventional drive does so much less work than blades deeper in the water, due to the reduced water density near the surface - Arneson, et al, said hey!, why not just take the upper blades above the surface? and the rest is history, although superventilating the prop also has a lot to do with it. How about trying to source a slightly smaller two blader with increased pitch? I think I have seen a formula somewhere for the trade-off for diameter to pitch. My guess is that this would be a custom job though.
On my project, the outrunner and batteries arrived from HK today - proposed C of G looks to be about the position of the main bulkhead, which looks OK to me - time to buy some ply and epoxy and start building a battery tray and motor mounts. By the way, what drive coupling do you use? I will water-cool the ESC (SeaKing 60), but I think I might try a small fan on the front casing of the motor.
Regards, Brendon.
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Don't forget the pics ;)
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the prop thing was a bit of a mystery to me, I had a lot of help from HS93. The boat was a 3 foot crashtender (Fireboat) and really became the learning curve for the Huntsman, albeit different boats, in shape and size, it was quite suprising how the prop altered things. I was running a 45mm "x", and had tried various sizes, and pitches, with a beautiful alloy racing prop being one of them, which had increased pitch, but the amp draw was dreadful. Luckily between us we had a choice of nearly 20 props, ranging from 35mm to 50mm, brass, plastic, alloy, various pitches, cleaver, steam, "x", "s", 2, 3, 4 blades. THe best in terms of gps measured speed, run time and amps wasnt the biggest, and lots of testing, with fully charged batteries to give constant readings. On trying a cleaver 3 blade, the amp draw dropped significantly, speed increased (marginally) the big win was run time, things ran cooler, and cosmetically the prop was true when running up on the bench.
I have noticed that the cheap plastic "x" props suffer from misalignment when bench testing, so for something like my Huntsman, under load, the prop must be suffering. Unfortunately the supply of props from donor boats and spares are nearly all 4mm, the Huntsman runs a 5mm shaft, as 4mm could not handle the torque and kept bending, so prop choice is a bit limited for testing. AS good quality props are expensive, I think until testing is complete I will wait to buy one. I plan to discuss my results with Propshop, and see what they make of the findings, with documented amp and temperature results, hopeful they can suggest a good quality alternative, at the moment its like running a F1 car, with remoulds :D
As for coupling, I dont use one, its a coupling free set up, shaft into boat, drive gear on shaft, motor driven by belt, all in one mount so its a perfect driveline, as the shaft support bearings are floating tiill everything is tightened up, therefore finding their perfect centre, if you know what I mean!
(http://s2.postimage.org/x9NGr.jpg) (http://www.postimage.org/image.php?v=Tsx9NGr)
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Doh! - stupid me, I forgot that you are running a geared setup (talk about short memory span) {-). I withdrew the old shaft today and found that it was slightly bent - along with a fair amount of wear in the top bearing where the shaft has been running out of true - also found one of the drive pins on the original IC coupling was bent (must have been vibrating quite badly). I am hoping to reuse the original shaft tube, straighten or replace the shaft and replace the top bearing - on which subject, can anyone suggest a suitable tool for driving out the tube bearings in situ? Looking at my new outrunner motor, it occurs that it is possible to use either end to drive the shaft on my direct drive set up - IE. use either the 5mm steel shaft on what would usually be the back end of the motor (wiring / mount end) in aero mode (which looks to me to be more suitable for a fan mounting), or the 8mm alloy prop adaptor bolted to the motor can - I'm inclined to modify the prop adaptor to fit a shaft coupling - thoughts on this, anyone?
Will arrange some pics when I start on the motor mount and spray rails / chines.
Regards, Brendon
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Something to aspire to ;)
(http://www.omra-uk.org/images/torquayimages/result4.jpg)
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Blimey Andy, that looks like Stingray about to launch into the wild blue yonder - or should that be Thunderbird 4? I think she needs a tad flap down %% Was the one "who ate all the pies" asleep in the aft cabin, leaving Barbie at the wheel :o
Hope I can make your donation run flatter <*<
Regards, Brendon
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Hi all, just an update on the Huntsman 31 build, I had a pretty disastrous bank holiday - I managed to open up my left forearm with a Stanley knife while removing the broken off flagstaff - cue quick trip to local minor injuries unit for a sutures and superglue job, then on Saturday contrived to go skating on a greasy paving slab and aggravated and old "war wound" from way back in the 70's >>:-( - oh well, am back on the build now. I have fabricated a motor mount from alloy plate and lined up with the shaft using a large rubber coupling from Model Boat Bits (8mm - 5mm) I am using the 8mm alloy prop-adaptor on the front of the motor to drive the coupling as I am not too keen on using grub screws on a plain shaft (even with "dimples" or flats. I just have to slot the mount baseplate and fit the hanger bolts into the bearers to complete the motor mounting. The battery tray is in and bonded down. Next to go in is the ESC. Have still not decided if I'm going to fit a cooling fan (did not go with the water-cooled motor mount in the end) - I was thinking of using a computor PSU fan as they only draw 20-50mA but I may try just ambient cooling for the start until I get on to the bigger props <*<. A question to Paul, Peter or Phil, what size rudder servo do you think I will need for the 46 inch Huntsman - and is there enough loading on it to require metal gears, or will a standard duty one do?
Still working on the photos :embarrassed:
Regards, Brendon (warrior193)
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Warrior
Way back in 1972 we used a standard plastic-geared, plain-bearing Futaba rotary servo for the rudder in the prototype. As the rudder is balanced then I don't think you'll need anything ultra-elaborate but one of these would be a good place to start
http://www.servoshop.co.uk/index.php?pid=HITHS325HB&area=Servo (http://www.servoshop.co.uk/index.php?pid=HITHS325HB&area=Servo)
FLJ
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Hi FLJ, thanks for the link :-))- one more thing, Paul (Red181) kindly sent me a diagram of the bottom strakes (spray rails) on his 28 as I need to replace these on my 31, his profile, viewed end-on, appears to be wedge shaped with the lower surface running approximately level to the water surface - can you confirm that the original strakes were this profile? it makes sense to me that they would be something like this to provide more lift on what was a fairly deep-V hull, but Paul did say that his were slightly damaged while removing thick paint from the bottom of his. I'm going to try to shape replacements from square strips of lime wood (should be fun <:(, unless of course, someone out there can suggest a better(i.e. easier :D) alternative. I know that there are three to a side on the full size boat, and that they run parallel to the keel, but from the marks on the bottom of my boat, mine appears to have had only two per side - was this a compromise on some kits? also, should they be evenly spaced from keel to chine?
Regards, Brendon.
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his profile, viewed end-on, appears to be wedge shaped with the lower surface running approximately level to the water surface - can you confirm that the original strakes were this profile?
Yes - they were this profile and they ran parallel with the keel from stern to bow. For some reason we only fitted two per side; that reason is now lost in the mists of time.
FLJ
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Hi Brendon, glad FLJ has confirmed the profile of the strip thingys :}
whilst on the servoshop link, last year they where selling digital unboxed full size servos for £15, I got one for my fireboat as the servo in it wasnt holding up very well, Steve Webb regularly "breaks up" box sets, such as tx, rx and servo sets, and sells seperate, might be worth asking him, or speak to Adrian, he is very helpful, I live 30 mins from the shop. It tends to specialise in fixed wing, helis and cars, but a lot of the stock we can use in boats . My servo is a cheap plastic gear, quite old, futaba, hold up fine, so far! :D
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I have ordered a pair of Towerpro 5010 servos (cheap enough for a spare) {-) and one of the Cods cheap 2.4Ghz Tx sets (cheaper than an extra Rx for my Spektrum) - I wonder if that means I'm a cheap *******? Got the motor mount finished - a bit "industrial" but it all seems to line up OK - I just knew that those bits of scrap alloy plate would be useful someday {-). Now to take the bull by the horns and try shaping the spray rails - it seems that no one can suggest a cheat for these, blast :((. Now to start fitting the ESC and batteries. By the way, does anyone out there know if Huntsman 31, aft cabin - hull number 7, or any of the aft cabin 31s took part in power boat racing? I know that most of the serious racers were the open cockpit version - probably due to lighter displacement - but some of the partial photos I've seen do appear to be the aft cab.
Must do something about those pictures too :embarrassed:
Regards, warrior193 (Brendon)
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You can buy balsa in triangle shapes, just glue and clamp them on to the hull, that's what it had before. The original strakes fell off when I stripped the paint off with the heat gun...
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Hi Andy, thanks for that - I've seen the triangular balsa, but the guy at Mick Charles didn't think that they would stand up to the punishment - I guess that I could brush epoxy resin into them to harden them up a bit (something like West System) That would save a lot of work O0
Regards, Brendon.
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Spruce...........and invest in a razor plane. Triangular balsa is the wrong section anyway, as the spray rails change in section as the angle of the vee increases towards the bow.
FLJ
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Rats!, of course you are right FLJ (by the way, what is your real handle?) I was grasping at any excuse to not have to resort to wood butchery. What do you think of lime instead of spruce, also is Evo Stick weatherproof (outdoor) glue waterproof enough for this application, or should I stick (oh dear!) to epoxy?
Regards, Brendon.