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Author Topic: Bluebird K7  (Read 7375 times)

BlazingPenguin

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Bluebird K7
« on: December 24, 2009, 03:37:16 PM »

I have been given a 12th scale kit of Donald Campbells Bluebird, the kit was designed 20 yrs ago to use standard brushed motors and nicad packs, but I think it would struggle to get on the plane. I fear that she may also just swamp herself in her own wash if shes not fast enough. These days we have access to brushless motors and lipo high amperage batteries, making it an altogether different proposition.

Essentially she's a surface skimming hydro with two sponsons

My query is what size brushless motor would I be looking at to drive a hydro with surface piercing prop and would it need geared like we do with other boats?
I even toyed with the idea of fitting one of the smaller ducted fans where the jet thruster would exit, just to give the impression of the jet working, any help on this would be appreciated guys !  :-))
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brodjack

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Re: Bluebird K7
« Reply #1 on: December 24, 2009, 06:04:31 PM »

What are the dimensions of the hull?
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BlazingPenguin

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Re: Bluebird K7
« Reply #2 on: December 24, 2009, 06:08:36 PM »

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brodjack

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Re: Bluebird K7
« Reply #3 on: December 24, 2009, 06:16:56 PM »

Nice model.
at just over 2' long it needs a largish motor,there is cheap and then there is good quality.
The equipment needed depends on what kind of budget you plan to spend??
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BlazingPenguin

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Re: Bluebird K7
« Reply #4 on: December 25, 2009, 01:06:16 PM »

Budget is my biggest restraint and no way round it Im afraid !

The stuff I have bought from China has been the exact same quality as over the counter here, better in some cases as so far non have gone on fire or blew up!
You'll know that the Bluebird isnt required to perform as other fast electrics, being essentially a straight runner, any steering only required whilst almost at rest. So no need for monster servos, motor itself would have to be up to scratch to get the speed, but runs are only ever going to be short & straight, so not a lot of strain there either?

One of my off-road buggies is brushless and does about 45mph easily (checked) but the motor does look a little on the small side to deal with drag from the water, there are bigger 1:10 scale ones that may be better for this, but I will always defer to experience for safety!  :police:

Still unsure if I would need a geared or belt drive to keep things within the realms of sanity?
Would 'normal' fast electrics use something? I didnt think nitro ones did, but amp draw/batt amp etc are pretty important here I think.
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brodjack

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EJL

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Re: Bluebird K7
« Reply #6 on: December 27, 2009, 03:30:13 PM »

 I did all the original development work for Touchwood to get this model to run well and I did an article for Marine Modelling International. The original set up was a hot 540 brushed motor on a gearbox but I later changed this for a Mega 22/30/2 brushles motor direct drive (astec) throwing a 3 blade X438 Octura prop.  The 3 blade stops torque roll. On 11 cells (nim cells) it is blisteringly fast - pops onto the plane instantly. Turning at speed is not for these models- straight line models.  I did some modifications to the sponsons running surface (not visible to most folk!) and I did away with the heavy resin fin making one out of lite ply laminated. I made my own surface drive flexi shaft system but I know ASTEC has made some for customers using my spec.

I have not tried mine with lipos so you would need to talk to ASTEC about that. Nims are about finished but if you just want it to run fast for your own amusement then some nims are still around. There have been a number of these models built and the builders who have followed my advice all say their model runs perfectly. Sadly there are some folk who went their own way and found a lot of difficulties. The kit is a tad heavy and thats why the power set up I used is needed.

 Ernie Lazenby
 (now retired fast electric expert)

BTW The original version with the hot brushed motor ran very well it did not bog down. Its much faster on the brushless mega motor.
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astecme

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Re: Bluebird K7
« Reply #7 on: December 27, 2009, 04:05:59 PM »

The mega 22/30/2 is 1770 rpm/v so on 11 nimh's it running at around 23000 rpm. The Feigao 540L11 is around 2250 rpm/v so too hot The 13 turn is closer. You could run with 3S lipo  (11.1v so you need about 2100 rpm/v) in which case a 12 turn would be better. NB the Mega is a 6pole motor and as such has immense smooth torque.
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BlazingPenguin

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Re: Bluebird K7
« Reply #8 on: December 28, 2009, 06:35:43 PM »

I did all the original development work for Touchwood to get this model to run well and I did an article for Marine Modelling International.

I've watched your video a few times since I found it Ernie...fantastic, in fact thats not even enough, without slipping into slang vernacular, its pretty hard to descirbe!!!!
You just 'know' that what your seeing & hearing inside that cockpit, cant be a million miles away from the view from the real K7...my god man, all you need is a mr Whoppit and youve built a time machine!

I agree with your findings regarding the tailfin and reached same conclusion for both that and the seat, which is also a hefty piece of resin, in fact most of the resin may end up being sidelined for lighter/stronger materials.

I've been searching around for a copy of "Across the Lake" too, with no success, but that looks a good movie, Anthony Hopkins really does look the part, makes Tom "Days of Thunder" Cruise look like a huffy teenager!

I will cut & paste your suggestions for future reference, if thats ok with yourself?
I've seen some of your excellent creations in magazines over the years, your reputation as a leading UK modelbuilder is well deserved.
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EJL

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Re: Bluebird K7
« Reply #9 on: December 28, 2009, 07:52:26 PM »

Thanks for the kind words- as someone who is now considered a  'non person' now by the MPBA it helps. One of the reasons I have packed in the hobby.

 The video of the 1/6th scale gas turbine K7 does show that model off quite well but its more impressive seen 'in the flesh'

I have got some video footage of the 1/12th Touchwood running flat out. I will try and get it posted on you tube or on the Astec site.

The resin seat in the Touchwood kit needs chucking out but not before one is carved out in blue foam and painted with acrylic paint.

I also did away with the cast resin planing shoes and made some from lite ply. (sponsons filled with white foam)

 If you want any help PM me- I dont build or run any more but am willing to help someone with the same interest as myself.

 BTW a film company wanted to use some of that youtube video footage- bottom line ,wanted it for free so I said no.
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DickyD

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Re: Bluebird K7
« Reply #10 on: December 28, 2009, 08:46:06 PM »

This is the link for Ernie's video, it is excellent.  :-))

http://www.youtube.com/watch?v=JNBRa3oKit8
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SteamboatPhil

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Re: Bluebird K7
« Reply #11 on: December 28, 2009, 08:56:41 PM »

I was lucky enough to have the stand next to Ernie at the Model World at South Sheilds, and belive me the boat is something to behold  :-)) :-))
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andyn

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Re: Bluebird K7
« Reply #12 on: December 28, 2009, 09:59:04 PM »

'Operator runs it at half throttle because of brown trousers'  {-)

Pass the transmitter this way  O0 ;)
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BlazingPenguin

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Re: Bluebird K7
« Reply #13 on: December 29, 2009, 02:21:56 PM »

I also did away with the cast resin planing shoes and made some from lite ply. (sponsons filled with white foam)

Planing shoes ?...Have to look inside the box again.
I was planning on blue foam once the sponsons were bolted in place, with perhaps a layer of resin to give the alloy planing surfaces something to grip?
Not sure, but I think I have a 1:12 scale pilot head for a plane, very light and looks similar to the pics of DC in a helmet, this would take the eye away from mods done to the resin seat etc.
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Wasyl

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Re: Bluebird K7
« Reply #14 on: January 04, 2010, 10:16:38 PM »

Here,s a Bluebird for you Bill......item number....130327837454... {-) {-)

Wullie
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essex2visuvesi

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Re: Bluebird K7
« Reply #15 on: January 05, 2010, 12:40:02 PM »

Sounds like fun with a wren minijet :)
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EJL

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Re: Bluebird K7
« Reply #16 on: January 05, 2010, 08:48:21 PM »

That one on ebay wont go with a wren mini jet (44) in fact at 20 lbs in weight without the engine or any internals it is 6lbs heavier than mine ready to run fueled up  (14 lbs)  Even with the bigger wren(45) it may struggle to plane.

 The key to success with gas turbine powered K7 models is to keep the power/weight raio at 1:1 which mine is and what the full size boat achieved.

 I am a liitle miffed that someone is using my name to promote a commercial model which if I am being truthfull is not that accurate.  It is also a little annoyng that hes using reference to my video to suggest his model can be made to go as well.  Dont think I can do anything about that.

 I know of a 1/5th scale version that would not plane even with a big AMT gas turbne in - reason far too heavy!   It would only pop out onto the plane when towed at round 25mph behind a full size ski boat.

 Gas Turbine powered model boats need to built as light as possible, much the same as fast electrics if they are to go quick. I have been saying that for a long time.
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essex2visuvesi

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Re: Bluebird K7
« Reply #17 on: January 06, 2010, 11:22:15 AM »

That one on ebay wont go with a wren mini jet (44) in fact at 20 lbs in weight without the engine or any internals it is 6lbs heavier than mine ready to run fueled up  (14 lbs)  Even with the bigger wren(45) it may struggle to plane.

 The key to success with gas turbine powered K7 models is to keep the power/weight raio at 1:1 which mine is and what the full size boat achieved.

 I am a liitle miffed that someone is using my name to promote a commercial model which if I am being truthfull is not that accurate.  It is also a little annoyng that hes using reference to my video to suggest his model can be made to go as well.  Dont think I can do anything about that.

 I know of a 1/5th scale version that would not plane even with a big AMT gas turbne in - reason far too heavy!   It would only pop out onto the plane when towed at round 25mph behind a full size ski boat.

 Gas Turbine powered model boats need to built as light as possible, much the same as fast electrics if they are to go quick. I have been saying that for a long time.

I quite fancy one, do you have any links to your models?
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Biscuit

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Re: Bluebird K7
« Reply #18 on: March 10, 2010, 11:50:11 PM »




Hi all not been on here for a while, but after seeing Ernie's Vids I thought I would dig it out again, I would really love to get this boat running, I have bought a ETTI 4960 motor and a 150 amp esc but have not a clue on the drive set up, prop and so on, this boats been on the shelf too long.
Ernie I have sent you a PM
Many thanks
Steve
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Biscuit

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Re: Bluebird K7
« Reply #19 on: September 25, 2010, 11:34:14 PM »

Boat still for sale.
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ooyah/2

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Re: Bluebird K7
« Reply #20 on: September 26, 2010, 12:24:29 AM »

Hi Biscuit,
Thought you had disappeared of the radar.
I followed your build and now have completed mine, have a look at the post before you ( water up the drive shaft ) ooyah/2
George.
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Jeremy

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Re: Bluebird K7
« Reply #21 on: April 03, 2011, 03:58:28 PM »

Just completed a conversion of the Touchwood kit.  I have followed OOYAH's build very closely so it should go - many thanks due for his advice and encouragement.  I would be interested to hear of anyone else's conversion of this kit - there must be several around.  Biscuit - did you ever get back to yours?  If so, let us know how you got on.









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