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Author Topic: MFA Piranha  (Read 10402 times)

cuppa

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Re: MFA Piranha
« Reply #25 on: December 31, 2011, 01:59:20 PM »

Thanks Nige.

Could you post a link to your website? I found a link in an earlier post but it does not work for me.

Cheers
          Jon
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Nige52

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Re: MFA Piranha
« Reply #26 on: December 31, 2011, 02:13:15 PM »

Jon,
My site is off line as I'm totally furbishing it, is there anything particular you need off it? I can email you HTML pages if that's a help?
Nige
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cuppa

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Re: MFA Piranha
« Reply #27 on: December 31, 2011, 02:24:14 PM »

Thanks Nige

I just wanted a look at your piranha build.  No hurry - I can wait for the site to be back on line.

Cheers
         Jon

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cuppa

  • Guest
Re: MFA Piranha
« Reply #28 on: January 01, 2012, 12:40:08 PM »

Nige's tip about heating up the plastic fender/rubbing strip worked a treat. It went on really well with no kinks and looks good.

Many thanks Nige!

Cheers
         Jon
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cuppa

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Re: MFA Piranha
« Reply #29 on: January 14, 2012, 11:56:35 AM »

Progress thus far:

Here is a photo with the 'lid off':


And with the 'lid on':
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cuppa

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Re: MFA Piranha
« Reply #30 on: January 14, 2012, 01:17:23 PM »

Have made and fitted a speed controller watercooling plate:

I cut away the heatshrink that was covering the speed controller's existing cooling plate and then fitted my home-made one on top of the existing plate with some heat conducting paste between the two to try and avoid any air gaps.

Not exactly sure if the watercooling is necessary but better safe than sorry.........
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cuppa

  • Guest
Re: MFA Piranha
« Reply #31 on: January 19, 2012, 07:55:43 AM »

The Piranha will be finished and ready for a test run this weekend.

The last jobs are to plumb in the water cooling and to wire up the motor followed by making a transparent deck hatch/cover to be taped down to provide a water-tight hull.

Have managed to buy 3 hardly used packs of 2s 5800mah lipos so we now have 4 lipo packs for it - excellent.

Made a stand for it by cutting a plastic food container to fit.

Must admit I am excited about seeing it on the water. In my eyes these 'vintage' boats have a visual appeal that is lacking in some of the more modern designs (Guess I am showing my age). The Piranha has a definite 60's look to it that I really like.

On to the next project.............(please don't tell the wife!).......... Now how can I smuggle another hull into the house?
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gregk9

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Re: MFA Piranha
« Reply #32 on: January 19, 2012, 04:20:35 PM »

You could always try hiding it behind a big bunch of flowers [for the missus!]  :-))
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cuppa

  • Guest
Re: MFA Piranha
« Reply #33 on: January 19, 2012, 06:06:16 PM »

You could always try hiding it behind a big bunch of flowers [for the missus!]  :-))

Say it with flowers - buy her a Triffid! (Only kidding)
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cuppa

  • Guest
Re: MFA Piranha
« Reply #34 on: January 22, 2012, 05:37:13 PM »

Piranha is now operational. First test run soon.
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cuppa

  • Guest
Re: MFA Piranha
« Reply #35 on: January 29, 2012, 12:34:06 PM »

1st test run now done and it did not sink!

It has a good turn of speed and handles well. Run lasted about 20 mins and the 5800mah lipo was still going strong. Couple of jobs to do following the run:

1) Increase rudder travel a bit
2) There was a small amount of water ingress - I think from the propshaft.
3) Shorten flexible cooling tube run to improve flow - the motor was just warm to the touch and the speed control was cold but I noticed the water flow was nothing more than a trickle so it may as well get improved.
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cuppa

  • Guest
Re: MFA Piranha
« Reply #36 on: January 31, 2012, 01:55:43 PM »

Mods now done.

I have re-routed the cooling pipes and have a shorter pipe run.
Rudder travel has been increased and I hope the water ingress is sorted - we shall see..... When i took the propshaft out of the stuffing tube there was no water at all in the tube which makes me think that this is not the source of the water ingress so I investigated further and now think the source was the rudder tube so I have re-sealed it.

Overall i am very pleased with the boat and my grandson is over the moon with it. It is fast enough as is so I do not plan to do any mods to increase speed. Fast enough to be fun and still be something that my grandson can operate with success and learn the 'ropes' before moving on to faster models (he is keen to go racing at some point in the future).

Now on to project Genesis........... The look on my gransdon's face when the genesis hull emerged from its box was a picture! (In James May's words 'enough to make a small boy faint'). He spent about 5 mins just looking at it and then ran into the kitchen shouting 'Nanny quick - come and see what Bampy has got!'

The Genesis will be a long build though - he is not yet ready for a boat that fast and it will take time to afford the required motor and controller. Building boats is addictive and the more i do the more enthusiastic i become. Must admit I like sorting out the 'engineering and electrical' side more than traditional wood building and so am happy to potter on with the Genesis while running the Piranha. It's all good fun.
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cuppa

  • Guest
Re: MFA Piranha
« Reply #37 on: February 26, 2012, 10:06:42 AM »

Ran the piranha again this morning. It is now watertight with not a trace of water in the hull after the run. The watercooling is still not working well though. I am going to re-locate the pickup. At present it is as per the plan directly behind the prop and it is not effective. Am going to block it off and add a flush fitting pickup as per a mini-eco type boat. I hope this will improve the cooling.
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triumphjon

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Re: MFA Piranha
« Reply #38 on: February 26, 2012, 08:12:02 PM »

cuppa , i had the same problems back at the begining of last season . i found its better to have the pick up slightly to one side behind the prop , remembering to locate it to the correct side so water is forced in by the spining prop !
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cuppa

  • Guest
Re: MFA Piranha
« Reply #39 on: February 28, 2012, 11:11:06 AM »

Ah well - finished the relocation of the water pickup and then re-installed the electronics only to find that the motor has developed a fault. Time to order a new one. I guess the inadequate cooling took its toll on the motor.
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cuppa

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Re: MFA Piranha
« Reply #40 on: March 13, 2012, 02:31:38 PM »

The tale of the Piranha continues.........

A new speed 600 race motor is now in place. I have replaced the cheap adapted model aircraft speed control with an MTronics 25.

Water flow through the cooling system is now much improved so hopefully the new motor will last a while........

The Piranha is currently my favourite boat - it is just such huge fun to run.
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Martin [Admin]

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Re: MFA Piranha
« Reply #41 on: March 13, 2012, 05:30:50 PM »


First run with a smaller propeller   :-))
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cuppa

  • Guest
Re: MFA Piranha
« Reply #42 on: March 13, 2012, 08:07:49 PM »

Yes indeed Martin

The prop that was included in the kit was an X35. The initial run on the new motor will be on a 32.5mm Graupner prop.

Cheers
          Jon
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cuppa

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Re: MFA Piranha
« Reply #43 on: March 20, 2012, 06:39:41 AM »

Ahhhh - that's better. Plenty of flow through the cooling system now and all is well.

Ran it on a 32.5 mm prop and then tried an S35 - motor and speed controller remained cool.
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