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[HS93 (RIP)]

don't forget the BEC  when we opened the cabin        Oh and who said go smaller first and keep bringing it in

Peter

[Flying Sparks]

Few months ago I was testing my floating gym palace, the Huntsman, decided, as it was very cold, and rain threatening, to just go straight for the biggest prop that would fit, for approx 5 seconds the boat was so fast I was petrified, then I finally achieved that elusive very black smoke that all smoke units cannot deliver, very impressive. Ubec literally blew up, the capacitor left the boat at a fast speed, one of the lipos died, and the esc fried (very impressively)Thats what you get for not being careful 

Thanks for sharing your story Red I will try not do do the same 

Do you know that the smoke that eminates from electronics is magic smoke. Magic smoke makes electronics work. If you let out the magic smoke it no longer works, as you found out 

Phil.

[HS93 (RIP)]

we had that much a guy at the other side of the lake thought we had a new pope.

http://www.orangecone.com/archives/2006/12/magic_smoke.html


I sent Paul the tune Smoke on the water he was not amused as it was properly not far off £200 pounds  went up be we think we found the problem out. which at least we know now what to look for, it happend so quick.

peter

[Flying Sparks]

My Precedent Huntsman had her first test runs today  Great fun. Todays runs were using a 2 bladed 45mm prop, it was too cold to try anymore. The first run was with a 8 cell Nimi, run OK but not up onto the plane. Second run was with a 3 cell Lipo, better just getting up onto the plane. The next run was with 4 cell Lipo, now we are getting some where, not blisteringly fast but a nice fast, scale like run. I attached my Eagle Tree data logger for these runs and a great supprise that on 4 cells I was only pulling a maximum of 18A. The speed controller is capeable of 60A cont and the motor about 45A cont and the batter pack about about 70A. So I'm well within the limits and nothing was even getting warm.
However I do have a handling problem that needs to be fixed before I try to tune for any more speed. When making a turn at speed to left or right and I give a bit too much rudder the hull rolls right over and if I don't back off it looks like she will roll upside down. The general feeling is that the rudder needs trimming down. Also I thought I might try mixing the rudder to the throttle channel and reduce the rudder throw at higher speeds. Any thoughts on this one?
Any how it looks very promising and was great fun. When I've got the handling sorted out and the weather is warmer I will strip her down for a repaint.

Phil.

[DickyD]

Rudder should only turn about 35 degrees or it acts as a brake .

[Flying Sparks]

Hi DickyD

Not sure of the rudder angle, I will check it tommorow. The problem was not loosing speed though, it was the hull rolling into the turn that concerns me

Phil

[red181]

phil, strange handling problem with that hull, is the cog high? what mah lipos where you using, where have you got them mounted?

[FullLeatherJacket]

Deep Vees do roll in turns - it's the nature of the beast. 30 degrees is more than enough rudder throw - or simply don't push the stick so far over at speed (that's why we have proportional radios  )
FLJ

[Flying Sparks]

Hi Guys

Thanks for your replys, Iv'e at last managed to get back out to the boatyard (garage) to have another look at my Huntsman. The rudder throw is 30 degrees either way. The Lipos are on the hull bottom next to the keel and the motor is mounted quite low. I'm going to trim a bit off the rudder as it looks a bit long, not sure how much though.
It's interesting to learn that deep Vs roll into turns though. I can drive the boat using the rudder so that it does not roll too much but I would like to prevent it rolling right over if possible.

Phil.

[HS93 (RIP)]

have you got a picture of the rudder servo linkage, it may just be that and we can offer a way of sorting it, I had the same with a fire boat , it was  OK out of the water but water pressure took it further than it locked.

Peter

[Flying Sparks]

Peter

I can post a photo of the rudder later, I'm a work at the moment  I don't think it's locking over though, as soon as I ease off the rudder the roll stops. Another change I going to make is the receiver. At the moment I'm using a simple 27MHz 2 channel. I will swap this for a 2.4GHz Spektrum receiver. With this I can program in either some exponential or mix the throttle channel to the rudder so that at higher throttle settings the rudder moves less. Or I could simply set a dual rate for rudder, using more movement for lower speeds. I think the mix would be best option but it will take a bit more effort to set up.

Phil

[red181]

Phil I dont think that you should have to go to all that trouble to sort the rolls out, something must be fundamentally wrong, have you looked at the last part of the video in my Huntsman build thread? There are some quite tight fast turns there, it does roll, but is really quite flat and handles real nice in turns, is your "roll" much more than in the video?

It might be the position of the rudder, rather than the size. I had a similar problem on another fast boat, rudder when too big was acting like a brake, and causing the bow to submarine. When Ramon was building his Huntsman, right to the point of testing, he had a similar problem with rolling, when he posted pics of the rudder it was right at the back of the hull. This could have been his problem as the boat was almost "hinging" on the rudder, if you know what I mean!. Where is the rudder positioned, try and load a photo for us to see  

[Flying Sparks]

Red, I've had a look back at your video, my Huntsmans rolls more than that. She goes to quite a scary angle. If you look back in this thread to the photo's that I posted you can see the position of the rudder tube. I will take some photo's to show the size of the rudder. The rudder is the one that came with the boat and not sure if it's the correct one, maybe it's too big.
Another thought, earlier in this thread Bluebird posted some pictures of a full size Huntsman showing a dagger shaped extension below the P tube, I wonder if one of these would help. I will fit one anyhow it looks good.
Many thanks

Phil.

[Flying Sparks]

Another thought on the rolling issue of my Huntsman: The full size has twin shafts, is this more suitable for this type of hull? Although looking at the photo's that Bluebird posted it looks like the full size props both rotate the same way, would this make the handling potentially worse

[Flying Sparks]

Photo attached of the rudder on my Huntsman. I was just about to hack a lump off the bottom of the rudder then I had a brainwave, my SHG Shadow has the same size rudder shaft but the blade is smaller so I have put the Shadow rudder on for a try. If this gives me less rock and roll I will cut down the nice shiny brass rudder and refit.

Phil.

[red181]

Hi Phil, been thinking about your prob, although mine is built from different plans (Veron) the principle handling should be very similar. I am certainly no expert, particularly in the company of this forum, but by process of elimination,

COG ok
Rudder looks same as mine
waterline down is same as mine

big difference is the position of prop and rudder. On Veron plans prop and rudder is closer to transom, and this could be the problem, we spent  a while changing the angle of the prop so the prop blade was close to the hull, and close to the rudder, which is much farther back than yours, unfortunately moving it is a big job, but if you look at Bluebirds pic earlier of the MTB its almost identical to the position on a full size Hunts.

I was out testing today, but the lake was just too small, and there was ice one end, but I was monitoring the roll in fast turns, and once it gets to a 2/3rd point on the hull it goes no further, keep us posted of your progress, pic of a real Hunts, and pic of my prop/rudder position, end of pic is end of hull  
sorry Derek, your thread has really been hijacked, perhaps Moderators could split it?

[Perkasaman2]

Hi FS,........As always   there are many pro's and con's for either single / double shafts and or rudders, but I'm thinking that the placement of 2 lbs of lead (initially removed) in the bottom of the stern may also have had an important role in the stability of the hull and also helped it to resist excessive rolling?
Shortening the length of  rudder plus moving  it's  con-rod to clip closer to the servo pivot on the horn may help steering. Both strategies will reduce the rate of turn/effectiveness of the rudder............ cautious tweaking/adjustment of steering characteristics may keep the adding of any additional lead ballast weight to a minimum. Although this fast deep vee hull is problematic, the advantages..............increased speed/comfort it gave in offshore racing in difficult/variable wave conditions more than compensated. These vee hulls need some weight for stability.......... The closer the running gear  is  to the keel bottom the better,  for optimum stability and resistance to rolling on turns.  Tweaking the location of the batteries is easier with Nimh sets and initially every possible placement should be thoroughly explored.    
Credit to FLJ, designer of the Huntsman kit for moderating the very deep vee of the original design to substantially reduce the liabilities for modellers of this offshore evergreen.
Enjoy the challenge these early racers faced.......... tweaking/honing the trim/handling... It can be a large chunk of the model boat fun, for many, including me.  
Before the advent of modern power adjustable tilt/ plates/tabs etc the challenge for these guys was to find an optimum set up for their boats for max speed in most  sea conditions......... it was'nt a millpond very often. One winning boat had her rudder and prop behind the stern so I would'nt worry too much about relocating the rudder.  
The modern RNLI designs although slower, provide excellent examples of  ultra stable deep vee hulls which successfully  'tick the boxes' for handling , stability and optimum speed offshore.    Apologies for the long post I hope some of it is useful.

[Flying Sparks]

Red and Perkyman, thank you for your help, much appreciated. It is possible to move the rudder back by about an inch. If you are familiar with the Precedent hull it has bulkhead just behind the rudder and before the transom, it would be major work to move the rudder to the rear of the bulkhead. The position of the prop is from the figures that FLJ gave me 145mm from transom.  I could move the battery pack further back and use two 8 cell NiMhi pack instead of a 4 cell Lipo. I notice on the photo that Red posted that the full size hull ans an extension behind it, I wonder what that is for?

Derek, sorry to hijack your thread. How's your Huntsman doing?

Phil.

[Bradley]

Hi Guys,
I am not in the least bit worried about you 'hijacking' the thread - I don't think you are and, in any case (as they say) every little helps.
I'm afraid that my Huntsman has not progressed very far at the moment but will post some pics (hopefully) in the not too distant future.
Keep up the good work, chaps - I am enjoying evry bit of it.

Derek.

[Perkasaman2]

Hi Phil, The original kit plan gave appropriate layout/build instructions suitable for a  single very light/powerful i.c. engine installation efficiently located  well forward in the hull ........however,using this layout/location for a much heavier electric motor will affect handling/stability issues. As the speed increases the bow is rising to plane and  raising this much heavier weight on the running 'knife edge' of the vee. It's understandable that the stern was heavily weighted to stabilise the hull..... especially, in sharp/abrupt turns at high speed to minimise rolling. Perhaps Fitting/swopping in a frantic/featherweight brushless motor may enable you to 'sweep away' most  issues and achieve the much higher performance of FLJ's original swift lightweight design without  altering layout or adding extra weight. Your small prop is a plus - high revs/well submerged/low drag, and avoids the weight and potential issues of shallower rear twin prop layouts. Trim adjustments with battery placement is also far easier and less obstructed with the forward engine placement. Going single  brushless could put a big smile on your face and save a lot of additional work......... Ideas/food for thought.    

[HS93 (RIP)]

all the running gear needs moving back 2" you don't want extra weight and a good brusless plus batteries is heavier than an IC motor and fuel etc, reds huntsman has a gear box that adds a bit more weight although it is a lot lighter than it looks, all the main weight is in the rear 50% of the hull in the front cabin is a receiver and batteries only, you do not want to put extra weight in it just kills speed especially with electric, we had to move the shaft back on red181s and reduce the angle that is why the underside near the prop still looks a bit tat as we wanted to be happy we had it right, the veron boat started with the shaft further back than yours more like the original boats but only a single, you need to have as much weight as low as possible, the rudder should not be a problem at that size, on the last boat we played with a fire tender chopping the rudder transformed the turning , but this is  a different shaped hull and needs it for slower running.

Peter

[Flying Sparks]

single very light/powerful i.c. engine installation efficiently located  well forward in the hull ........however,using this layout/location for a much heavier electric motor will affect handling/stability issues

I am using a brushless motor that is in roughly the same position as a ic engine. My motor weighs less than an ic engine and also I used 4 cell Lipo that weighs about the same as tank of fuel. Speed is not an issue, I have plenty of that, and I believe there is much more to come when I try different props. First I want to iron out the excessive rolling. This weekend I'm going to try a smaller rudder and moving the battery pack further back.

Thanks guys 

[Flying Sparks]

I managed to get another test run in today. I put a smaller rudder on and the rolling is defiantly less twitchy, still rolls but not as sensitive. So now I will cut down the original rudder and refit. Another change is I've switched this model to 2.4 radio, won't make any difference to the handling but I want to try mixing the throttle channel into rudder to give less throw at higher power settings. I changed the prop to a X45, more speed and now pulling 22 amps, still well inside the limits and the motor/esc/battery barely gets warm. I don't think it needs to go any faster she is planing right out of the water now, looks great. Also I will try a little weight at rear.
Will post some piccys soon.

Phil.

[Bradley]

This is as far as my Huntsman has progressed to date (not very far but we are getting there, slowly).  The framework is installed into the hull using P40 and the rudders are temporarily installed.  I think that the next step will be cut the slot in the hull for the shafts and set them up along with the motors.  Think I will try BB700 Turbos to start with and then if they don't have enough 'get up and go' I will try brushless.

Derek.

[Flying Sparks]

Hi Derek

Nice to see some progress on your Huntsman, looking good 

Just an idle thought, has there ever been a Huntsman gathering as there must be quite a few models around 

Phil.