Precedent 34″ Huntsman

[BarzoParticipant @barzo]

Mark,

 

Thanks for the reply and the reassurance.

 

I note from another forum you are interested in power/prop. size calculations.

 

I currently have a 45x plastic prop. on this model. It was perfectly suited to the previous incarnation, when this boat had an IC engine rotating at approx. 15000 rpm. Do you have any opinion on what sort of prop.I should be running with, using the  900 motor and 20 volts, with an anticipated 25 amp current consumption?

 

Cheers Alan

[Mark Beard 1Participant @markbeard1]

Alan,

 

I like to think I know much more about motors than model boats, though I’m trying to learn.  At 25A you’ll be running between the peak-efficiency point and the max-power  point, which sounds about right for a fast boat.  The thinking I’ve done on prop speed is for scale displacement hulls, where I’ve considered a tip speed of 10m/s to avoid cavitation.  If you do run at 25A then the prop will be doing 7500rpm so you’ll likely be running at a tip speed of around 18m/s.  Maybe this is okay for a fast boat which may run with a cavitating prop. 

 

Any fast boat bods out there who can advise?

 

Mark

[BarzoParticipant @barzo]

Hi Folks,

 

For those that are interested, I have uploaded two pictures of the new power layout.

 

Quite a bit to be done on the cosmetic front, but it can now be test driven.

 

Must remember to close off the water cooling feed from the previous incarnation!

 

 I have decided to revert to Dave’s original advice on the prop. size and have re-fitted the 50X prop.

 

[BarzoParticipant @barzo]

Does any one know what the designation ‘X’ or  ‘S’ means when quoted with the prop. diameter?

[Mark Beard 1Participant @markbeard1]

It refers to the pitch.  X has a coarser pitch than S.  For the same diameter, an X will drive the boat faster (only if it runs on the front side of the torque curve) but will load the motor more, drain the battery faster and heat the motor more.

[BarzoParticipant @barzo]

Mark,

 

Can you be more specific, ie what diam. to pitch ratio?

 

Alan

[BarzoParticipant @barzo]

Gentlemen,

 

With some 800 visits to the thread, there are clearly quite a number of lurkers.

 

 Have these postings been of any help?

 

If so how?

 

Cheers Alan

 

 

[Mark Beard 1Participant @markbeard1]

Alan,

 

I wish I could be more specific on pitch:diameter ratios but alas not yet.  I’m studying prop and motor matching to hull size and performance and  hope to know more in due course.  I’m getting some great help from Tom and Gareth.  If I learn anything new which may be of interest or use to others, I’ll post it on the forum.

 

Cheers,

 

Mark

[Colin BishopModerator @colinbishop34627]

Hi Alan,

 

We do seeem to have more than our fair share of people who look but don’t post.

 

Don’t let it put you off.

 

Colin

[BarzoParticipant @barzo]

Hi,

 

For those interested in the RadioLink  T4EU/Action P98 combo.

 

Whilst I have found that the ritual of switching on the Tx and moving the throttle to full reverse etc., as described above, works every time, I have found that trying to find the ‘neutral’ position quite problematic. Even with the Action DIP 4 set to ‘on’, the width of ‘neutral’ is two clicks either side of the nominal ‘neutral’ position.

It is my intention to experiment with two alternative solutions:

   1.   In mode 2, trying if possible to have the joystick biased by springs to the ‘neutral’ position rather than the ratchet mechanism, as at present.

   2.   reconfiguring the Tx to mode 1, thereby moving the throttle to the right-hand stick.

 

Cheers Alan

[BarzoParticipant @barzo]

Hi,

 

Whilst on holiday it struck me that with the uncertain nature of finding the ‘neutral’ position of the throttle stick and the sensitivity of the response I could find that I was driving the boat astern at some twenty amps. This I am sure would sink it!

 

The importance of a self centring throttle stick suddenly became mandatory, not a nice to have.

 

Cheers Alan

[BarzoParticipant @barzo]

Hi 

A hiccough on my journey.

On carefully opening up the Tx., to change the ‘mode’ switch, I noticed that the left hand control gimble (when looking from the rear) had been badly damaged.  

I contacted GiantCod via the web site and was allocated a support number. The Tx/Rx has been duly returned to GC. We await their verdict. I must say that the guys at GC have been very helpfulI

I would make the point that since the unit is delivered bubble wrapped, in a jiffy bag, it is extremely vulnerable to the tender mercies of the Royal Mail! 

Cheers Barzo.

PS I have decided to lay a teak veneer deck as researched from various Fairy web sites.

 

Edited By Barzo on 21/11/2010 11:17:31

[BarzoParticipant @barzo]

A little bit tardy, but here goes.

The RadioLink set was returned by GiantCod probably two weeks ago. Everything is now Tickerty Boo. Full marks to all those at GC who helped me out.

I have now finished the laying of the teak deck – pictures to follow -. The next job is to start the painting of the Hull. The colour scheme will be white topside  with blue antifouling and a black boot topping.

Barzo

[BarzoParticipant @barzo]

Bye the bye, does any one have any experience of relating Froude’s scaling rules to model boats. I am a bit sceptical of the power scaling factors.

The Huntsman looks to be powered by two engines, giving approx. 480 shp giving a max. planing speed of approx. 30 knots.

For my model at 34 inches (scale approx. 11:1)  would give 9.95 knots with .11 hp – 82 watts.

A boat weighing 8.26 lbs., with a motor running with 12 volts (no losses) consumes 6.82 amps.

The watts and hence the amps with 12 volts do not seem enough – where am I going wrong?

Cheers Barzo

[phill dParticipant @philld]

Regarding the prop question a while back you have a x45, the x standsfor the pitch ratio.

X  means 1.4 times the diameter.

 

And the huntsmans hull can go a lot faster than 30 knots.

They were capable of 33 knots when in full race mode back in the 60’s, since then many people have put larger hp power plants in them and got 40 knotts out of the 31 footers..

 

When you were running a 6.5 cc in the hull its would of been very very fast.

 

 

Its a very nice boat the huntsman, i used to have the 48inch version with 10cc enya

went like a dream.

But like you say, not many places left to play with ic engines.

 

I now use river, sea and old gravel pits wherever i find them  ha ha

 

Waiting to hear how the boat goes and see new pics.

 

 

 

phill

[BarzoParticipant @barzo]

In a separate thread I have been pursuing the Froude scaling rules.

The conclusion is that the realistic interpretation of model HP requirements is approx. x5 times the Froude scaling calc..

As shown above the straight power calculation results in 80 watts. When modified by the x5 factor gives 400 watts. This figure is, to my mind, more credible. 

With the batteries fully charged to 20 volts this would require 20 amps. This at least matches the ESC capacity I have installed.

Ah well we will soon see.

Cheers Barzo.

[BarzoParticipant @barzo]

Dear All,

 

At last the moment has arrived when the boat was finally put to the water. On a bright spring Sunday morning, (see newly added photos).

 

The weight of the boat is something of a surprise and to which the additional copper water cooling coils has been been of no small contributor.

 

The performance, whilst certainly faster than scale was satisfyingly fast enough to have the beta blockers earn their keep.

 

The Action electronics performed well and the Radiolink rc system behaved as required. I will convert the throttle stick to have a self centering feel rather than the ratchet feel.

 

Trying to engage a small amount of reverse was quite difficult and I very nearly drove it under in reverse!

The Motor was very very hot, I think the 50 mm prop had disturbed the water flow into the cooling pick up. I will try the original 2 bladed 45x prop again. In fact I have ordered a brass 3 bladed prop to experiment with as well.

 

The Action P98 cooling fins were hardly warm, very satisfactory. The setup, as it is, gives me a good half an hour of pootling around the lake in Clevedon.

 

I have been trying to purchase aluminium tubing to make a lighter cooling coil but have not been successful yet. In the mean time it has been suggested to me that I might try silicone tubing. Any comments anyone?

 

Thanks again to all those folks that have helped me on this journey – and now to the next one – will it be a re-engined Huntsman with a Brushless motor or perhaps the Hydrofoil with a conventional brushed motor I haven’t decided.

 

Barzo

 

 

[LARRY WHETTONParticipant @larrywhetton68737]

HI BARZO, nice model lots of fun on the pool , ….

here is my swordsman. running on a 540 motor 15 amp esc 3700 7.2race pack 40 mm wizzy bit bit of a goer LARRY

[Dave MilbournParticipant @davemilbourn48782]

Alan

Silicon tubing is an insulator of heat; you need a heat conductor for cooling coils, with perhaps silicon tubing to take the water to and from the scoop/outlet.

Dave M

[BarzoParticipant @barzo]

Hi all,

I have posted a short video of the beast on youtube

– http://www.youtube.com/watch?v=Btu3BMTHJA0 –

The quality is not brilliant and I will borrow a proper video camera for the next attempt.

The 45x prop was definitely slower, but the battery life, as expected, was greatly increased and the motor ran a lot cooler.

The brass prop has just arrived, o’ frabjous day!

Cheers Alan

Edited By Barzo on 15/04/2011 11:45:53

[BarzoParticipant @barzo]

Edited By Barzo on 15/04/2011 11:43:55

[Tony BurtonParticipant @tonyburton83970]

Hi Barzo

I have been following your story over the weeks and now I`ve seen your video on youtube it proves that you dont nee i,c engines to get speed these days. I have a Seaplane Tender 206 which I built last year with 2 tiny brushless motors turning 40mm props and its very fast.. Well done

Tony

[BarzoParticipant @barzo]

Hi All,

I have had a thought to try engine sound effects, that are proportionally loud to the throttle opening . Has any one out there done this?

The boat has approx a half a pound of lead in the back so I don’t think I will have a weight problem

Barzo

[Dave MilbournParticipant @davemilbourn48782]

Has any one out there done this?

 

Just one or two, Alan!

We’ve already sold 230 of these……..http://www.action-electronics.co.uk/pdfs/P100.pdf

BTW your upgraded P98 will be on its way today.

Dave M

[BarzoParticipant @barzo]

Dave,

 

‘Ripper’!

 

Many thanks .

 

It will take some time to reconfigure the internals.

 

I will certainly experiment with the trimming.

 

Cheers Alan

 

 

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