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Author Topic: Fairey Huntsman - Old timer  (Read 8351 times)

olly4950

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Fairey Huntsman - Old timer
« on: May 18, 2012, 08:03:40 PM »

Hi To All,
Forty odd years ago I built a 46" wooden Fairey Huntsman, at the time it was powered by a Merco 61, but today I have a brushless motor(EMP 5065 300 kV approx 7000rpm) on a 14/16 tooth gearbox(built from ideas off this forum)
The ESC is a swordfish 120amp
6 cells(22v) 5amp
52.5 plastic prop
Straight shaft

The boat is solid in the water at all speeds(fastest speed clocked is 14mph)
The problem I am having is that she lifts to far out of the water, it as been suggested by club members that I need more weight in the front of the boat, I feel that this will had more useless weight to the boat.

My question is could I add a trim tab like the real thing? But would this change the characteristics of a good solid boat?
or could I move the batteries to the front of the boat.
The fastest speed recorded from one of the members on this forum was 21mph, I have the same setup so why is mine slower?
Any body got any ideas?

Regards

olly4950
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Tug-Kenny

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Re: Fairey Huntsma - Old timer
« Reply #1 on: May 18, 2012, 08:12:23 PM »


I'm no expert, but your suggestion of moving the batteries forward seems a good idea.

ken
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red181

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Re: Fairey Huntsma - Old timer
« Reply #2 on: May 18, 2012, 11:00:41 PM »

Hi Olly, I have reached 32mph with my Huntsman, it planes very flat if that makes sense, I have 2 x 3 cell lipos either side of the motor, which is pretty much in the centre of the boat.

If you want speed, adding "dead weight" is totally wrong.

I have settled for a set up that produces 24mph, but this took a very long time to reach a setup that gives me what I want with speed, and a run time that I am satisfied with, which will horrify some, its 15 minutes, or if I back off the gas, nearly 20 mins, but that never happens!

I suspect your prop angle may be too severe, and you are losing forward thrust in leiu of upward thrust, also how free and good is the driveline?. Using an eagletree data logger, I can record GPS (so I know my recorded speed is accurate), amps, watts, revs, mah , its amazing how much the amp draw increases, and speed decreases if for example there is drag/tighness in the drivetrain, even misaligned gears can add to speed drop.

I notice your kv rating is very low, this will give good torque, for a boat like a tug, but will not produce the revs you want for speed, I did extensive testing with a number of brushless motors, 1650kv, 1200kv, 800kv and 880kv, which I now use with a gearbox

to give you an idea, here is my current setup, and statistics, which where two weeks ago:

ratio 1.5:1 (30tooth on shaft, 20 tooth on motor)
X55 "X" Prop, GPS 24.74mph, 82amps, 19329rpm, 2660 watts (all "spike" readings), with a 3 blade beautiful cleaver propshop the boat nearly turned over with the torque!

more info, and pics might help further, I will help as much as I can! :-))
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olly4950

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Re: Fairey Huntsma - Old timer
« Reply #3 on: May 19, 2012, 11:55:31 PM »

HI,
Thanks for the advice.
Could you tell me which brushless you have?
My shaft has a ball bearing at the motor end with a teflon bush at prop end.
I have moved batteries to front of motor, so I am hoping this will help.
Photos show setup and angle.
Regards olly4950
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HS93 (RIP)

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Re: Fairey Huntsma - Old timer
« Reply #4 on: May 20, 2012, 12:48:54 AM »

how tight have you got the belt? it needs to be quite slack , you should be able to push one side of the belt to at least the centre line between the two shaft's . the batteries to be eather side of the motor and you shaft angle looks all wrong to me to much air between hull and prop .

BUT that is just my opinion.

Peter
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red181

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Re: Fairey Huntsma - Old timer
« Reply #5 on: May 20, 2012, 12:59:24 AM »

this motor

http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idproduct=11143

proved to be very good, they appear now and again on ebay, look in rc helicopter searches as they are used in helis, I picked one up for 25.00, its a good motor for the money. I now use a scorpion motor that santa gave me last xmas.

Looking at the pics, and this is just my opinion, if thats a 52.5mm prop, the gap between the hull and blade tips is too big, the angle is too steep, meaning you could be losing forward thrust as the prop is pushing "upwards".

I was mortified when my mate took a pair of mole grips to my prop which was a similar angle when we started the refurb, but he was right, yanked it out and reset the angle, the gap needs to be as small as possible allowing for what size prop you run. Interestingly the 52.5mm gives  a good balance of lower amp draw and reasonable speed, 23mph. I rubbed it down with wet and dry, and painted it, then polished it up (saddo! :D) I also took 1mm of the trailing edge to reduce the amp draw.

I would think with that kv motor you could experiment with a gear ratio much closer to 1:1 to up the revs, and possibly a larger prop, does the motor get hot when running? 
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olly4950

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Re: Fairey Huntsma - Old timer
« Reply #6 on: May 20, 2012, 10:58:18 AM »

Hi to all,
Thank you for all the advice.
The distance from the hull to the center of the shaft is 50mm, what distance should it be?


Red181
You mentioned a Scorpion motor, which one do you use?
My motor runs very cool.
The revs are approx 7000rpm on the 5065 motor.

Alan
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grasshopper

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Re: Fairey Huntsma - Old timer
« Reply #7 on: May 20, 2012, 11:06:26 AM »

If you're running 'very cool' - you obviously can up the ante a little.

Got to agree with previous postings about the propshaft angle - if you could refit and at the same time get rid of the belt drive ( which looks close to a 1:1 ratio anyway) and go direct drive you would be better served.
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HS93 (RIP)

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Re: Fairey Huntsma - Old timer
« Reply #8 on: May 20, 2012, 12:48:25 PM »

I would keep the belt drive you will find you can be more flexable in the set up, Paul tried 1.1 and it was no help , what the belt drive does is enable you to make a higher KV motor act like a lower KV motor so you don't have to have a bucket of motors and at the price of the Scorpion motors that is a bonus.
Peter
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red181

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Re: Fairey Huntsma - Old timer
« Reply #9 on: May 21, 2012, 01:03:01 AM »

Quote
My motor runs very cool.
The revs are approx 7000rpm on the 5065 motor

Alan, I have sent a link for the motor, I think your revs are too low, how are you measuring rpm and speed?

cheapest option at this stage, try a "x" 55 prop, short run, test the temp, see what happens, then look to change the ratio, gearbox is the best option to try a lot of different settings, if you end up with 1:1 at least you will know what works,

Paul
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olly4950

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Re: Fairey Huntsma - Old timer
« Reply #10 on: May 21, 2012, 12:50:10 PM »

To all, many thanks for your advice.

Red181 thank you for your message.

Where can I buy the X55 5mm plastic props from?

I am also a little confused to the suggestion of a 1:1 on the gearbox using the setup I have now.

I have considered changing the motor for Red181's suggestion from Hobbyking or to buy an Align 600 1200KV, would like to know what the gearbox ratiio
would be for this?

The speed was recorded on a phone with a GPS app. This was first calibrated against my speedo in the car.
The revs: I used a digital laser tachometer.

There is no space for an inline setup thats why I choose the pulley system and also I could experiment with gear ratios.

Alan

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susieq

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Re: Fairey Huntsma - Old timer
« Reply #11 on: May 22, 2012, 09:01:47 AM »

Alan, I have sent a link for the motor, I think your revs are too low, how are you measuring rpm and speed?

cheapest option at this stage, try a "x" 55 prop, short run, test the temp, see what happens, then look to change the ratio, gearbox is the best option to try a lot of different settings, if you end up with 1:1 at least you will know what works,

Paul
Hi Paul, put me in my place if I'm out of turn. I don't know if you've realised but olly 4950's  boat is the 46inch model and will probably need a more powerful motor than yours, if I remember yours is the 36 inch. Regards Alan (used to be aslo44)
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HS93 (RIP)

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Re: Fairey Huntsman - Old timer
« Reply #12 on: May 22, 2012, 09:24:26 AM »

Pauls boat is a Veron Huntsman 28 and it is 42" all timber boat , not the lightest boat to get moving it has not been lightended at all. Alan (olly4950)  have you got any pictures of the outside of your boat?

Peter
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olly4950

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Re: Fairey Huntsman - Old timer
« Reply #13 on: May 22, 2012, 09:12:28 PM »

Photos attached of my old timer.
She is the Precedent kit built 40 odd years ago, she weighs approx 7KG
and is powered by a EMP5065 380KV running at 8900rpm.

Just ordered some new plastic for screen and brass for bow rail.

Any one have dimensions for bow rail?

A bit confused to why I should use a 1:1 ratio on the pulley gearbox?

Regards
olly4950
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HS93 (RIP)

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Re: Fairey Huntsman - Old timer
« Reply #14 on: May 23, 2012, 01:29:09 AM »

looking at the prop set up you need to re install for electric, it all needs to go towards the back it seems drastic but when we did Paul's it took a night to do the shaft and I work very slow rudder is no problem then a lot of  your problems will go away re mounting motor etc  Paul's is about the same weight as yours, he will better tell you about the 1.1 ratio , but I think he is saying you will lose nothing even if you ended up one to one , but he found when getting close to one to one the amps hit the roof and the speed went down , BUT he picked the motors with the gear box idea in mind.

Peter
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red181

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Re: Fairey Huntsman - Old timer
« Reply #15 on: May 23, 2012, 07:42:20 PM »

Quote
Hi Paul, put me in my place if I'm out of turn. I don't know if you've realised but olly 4950's  boat is the 46inch model and will probably need a more powerful motor than yours, if I remember yours is the 36 inch. Regards Alan (used to be aslo44)

Hi Alan, mine is the 42" one also, but the veron design, so there are some fundamental differences, the biggest being where the shaft is, size of boat is the same :-))

this is what happened to my different settings, I keep a record of all of them I suggest you do the same! ;)

if we for the purpose of simplicity just concentrate on one prop, "x" 55mm two blade, available from any model boat shop, same batteries, always fully charged, and very similar weather conditions, all readings will be relevent to the fastest (maybe not most efficient) recorded gps speed (by the way, reason I asked, so many people just guess what speed the boat may be doing! :})

align 1620kv, 2.5:1 ratio 24.1mph, 64amps, 1389amps, VERY hot motor after 5 mins, it was watercooled,

Turnigy 880kv (as recommended) 1:1 ratio 25.55mph, 104amps, 2037 watts batteries where getting sucked dry with that massive amp draw in minutes!
1.14:1 ratio, 23.94mph, 82 amps, 1644 watts, motor was warm

The scorpion motor is more efficient as it can handle the demanding set up better, but pound for pound the turnigy was better value, the align however was an outrunner, with an outer can, and made a superb sound, like a jet turbine,  :}

I suppose on 1:1 I could have used less volts! its a real interesting thing all this testing, and so suprising how just changing one gear by a couple of teeth makes such a difference, I have used 1.14:1, 1.25:1, 1.67:1. 1.43:1, 1.6:1 and 1.5:1 !!!!!!! with the scorpion, strange ratios, but its just using what gears I had, best setup is 1.5:1, 30 teeth on shaft, 20 teeth on motor, "x"55 with scorpion, pity you are not in north west, I could show you!

hope that hasn't confused you too much!

Paul

 
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Re: Fairey Huntsman - Old timer
« Reply #16 on: May 23, 2012, 08:43:09 PM »

Photos attached of my old timer.
She is the Precedent kit built 40 odd years ago, she weighs approx 7KG
and is powered by a EMP5065 380KV running at 8900rpm.

Just ordered some new plastic for screen and brass for bow rail.

Any one have dimensions for bow rail?

A bit confused to why I should use a 1:1 ratio on the pulley gearbox?

Regards
olly4950


Oi! Away with your "40-odd years". Don't make me feel any older than I already am! The kit was designed ovet the period April - July1972, not a minute before.
Seriously, if you have access to AutoCAD R14 or later then I can send you a scan of the original plans. PM me if this is OK.
Dave M
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olly4950

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Re: Fairey Huntsman - Old timer
« Reply #17 on: May 28, 2012, 10:22:24 AM »

Going on Wednesday afternoon to try new setup,  batteries further
forward with a X55. Testing again with phone gps.
Would like a few more mph or knots. If not, it will be a winter again to remove propshaft.
Having to much fun with my old timer to change it now even at 14mph.

 Would it be possible for the angle please?

DAVE M

Thank you for your offer.,  but I don't have Autocad.
Many thanks for all advice.
olly4950
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essex2visuvesi

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Re: Fairey Huntsman - Old timer
« Reply #18 on: May 28, 2012, 10:46:32 AM »

you dont need autocad to view the files
Dave sent them to me and I used this program

http://www.3ds.com/products/draftsight/overview/
Its free as well!
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olly4950

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Re: Fairey Huntsman - Old timer
« Reply #19 on: May 31, 2012, 01:58:42 PM »

New setup
Tried a new X55 prop with batteries further forward
speed was about 11mph less than original setup.
Swapped various props still no improvement.
Waiting for a T600 before anymore trials. If that does. not do the trick,  then come winter I will fit new shaft at a different angle.
Olly4950

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red181

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Re: Fairey Huntsman - Old timer
« Reply #20 on: June 05, 2012, 07:51:36 PM »

Olly, you say you are running 6 cells, what sort of batteries are they?
(sorry if I missed that info)
thanks

Paul
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olly4950

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Re: Fairey Huntsman - Old timer
« Reply #21 on: June 05, 2012, 08:05:36 PM »

Hi red181
The batteries are lipo 6 cells  2 x 11.1v 5000mah
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red181

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Re: Fairey Huntsman - Old timer
« Reply #22 on: June 07, 2012, 09:44:35 AM »

thanks for that info, with those batteries, and an "X" 55 prop, you shoud be seeing better speed, so, assuming the transmitter/esc is seeing a full throttle range, )its possible that this could have been dropped with all the work you are doing, it happened to me, I was scratching my head for ages, then a friend suggested connect the motor direct to the battery and see if there is any difference in the revs, I keep coming back to the very low KV of the motor, and the distance between the tip of the prop and the hull.

A quick answer might be to borrow from a fellow club member a much bigger prop, maybe a 3 or 4 blade with a good angle on the blades, like a cleaver style (see propshop's site for pictures of the differences), and just give the boat a very short blast, you should then see an improvement in speed, or maybe more improvement in acceleration, keeping a watchful eye on motor temp. This might be an easy solution if you dont fancy getting the shaft tube out, or going to the expense of a new motor

What size shaft are you using?

Paul
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olly4950

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Re: Fairey Huntsman - Old timer
« Reply #23 on: June 07, 2012, 09:04:51 PM »

Red181
On holiday at moment, will let you know length of shaft tomorrow when I return home.
Got a new motor coming soon T600 1200KV.
Would like to know the distance from the hull  to the centre of the propshaft or the best angle? so I can change this.
regards
olly49
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olly4950

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Re: Fairey Huntsman - Old timer
« Reply #24 on: June 08, 2012, 02:20:11 PM »

Hi Red181
I have measured the shaft it is 16.5"
It is 2" from hull to centre of shaft
From rear of hull to tip of shaft it is 9"
Rudder is 5.5"from rear of hull.
The propshaft was from Prestwich models and has a roller bearing by motor.
My new motor arrived today and a little filing to motor mount is required,  so I have had to take mount our,  at this point I am thinking what is stopping me from taking old shaft out and putting
 new shaft in. Need advice on dimensions please.?
Should I buy the same shaft?
If so what size?
Should I put in a position frame?
What angle?
olly4950

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