Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[Tim_M]

One thing that was a success was the sealing. When I took the hatch off, it was bone dry inside - not a drop! Mind you, I did obsess a bit over that part of the design. The 'engine intakes' are closed off so it's very difficult for water to get anywhere near the hatch. There's a deep coaming and the hatch gets sealed with tape before the top goes on. As for the river, I'd only take the boat there if I had a full size safety boat to go after it. Nearly ended up in open water many times as a kid 


Ian - keep your voice down! Bob is very sensitive and if he gets upset I'll never see my boat again!

[ballastanksian]

Don't worry Tim, Bob, Nick and I had a good conflab last weekend at Wicksteed and he is a lovely chap. The frustration of such catastrophic problems appearing in the middle of the water rather than on the bench would have had me vexed somewhat.

[Tim_M]

Crossed line I think, Ian. My Bob is a minion. Who's yours? 

[John W E]

hi there, I realise I am opening up an 'old' topic.   However, what I have done is quite relevant to this topic - I have been scrolling away on the QT - building my Bluebird K7 - operated by a ducted fan.  My model is 1/8 scale - and the ducted fan is 80 diameter - with 12 blades.  Running on 2 voltages for testing - the first was run on 14.8 batteries just to find out the characteristics of how she handled.  Then when I was happy and ironed out a few faults, I upgraded the batteries up to 11.1 giving a total voltage of 22.2 volts.   Now all I need is a BIGGER lake, to allow the model to achieve its top speed.   As I was having to throttle it down 1/3 of the way down the length of the lake cos she ran on 'no power' for a good distance.


There's a short video on YouTube - which I will put a link on later - or you can go over to Model Boats forum where you can see the link there.   
TRIALS AND TRIBULATIONS | Model Boats


Here are a couple of pictures.


John

[DBS88]

You really are making a good job of the build and have achieved impressive performance. You definitely need space to run at anything like top speed because things happen very quickly, its very nerve wracking! Here is a video showing the Bluebird K7 that I am fortunate enough to look after and now enjoy using her on occasional demo runs, she's too fast for normal use on the lakes where I am a member.


https://youtu.be/LtfEfWmWirg?si=A5LAT6rEuWheX8AD

[Tim_M]

Wow, that's brave, and beautifully executed! I looked at this years ago and came to the conclusion (in my mind, not in practice) that water would get into the fan and - kaboom. My very first attempt at a Bluebird style model (about 50 years ago) had a ducted fan. Some sort of vent-axia impeller and a 540 motor, as I recall. It moved, if you looked really close.


I'm impressed that you get up on the plane without over-sized shoes on the sponsons. On my model, the weight was well forward to compensate for the upwards torque from the prop. Yours would need to be the opposite as your thrust is above the waterline, which might account for it. Can't see in the photos if you have the little fins at the back of the sponsons. Worth trying if you don't to help with the steering.


In the video, your model looks great. Plenty fast enough. But, yes, you'll need a loooooong lake! Mine scared me so much I let it go to a better home. From the post above, looks like it's still being enjoyed. 

[John W E]

hi there Tim M the comments are much appreciated.  I am unsure whether you have read/following the posts on Model Boats Forum about the first sea trials I did with her - where I literally flooded the hull.  This was due to the fact that I did not have the side perspex shields on either side of the intakes.  Nor did I have the 2 long stabilising fins either side of the inside of the sponsons - consequently we shipped gallons of water straight into the hull and right into the fan.    She didnt come up on the plane that day.   So disheartening.


But, dried her out - and funnily enough (touch wood) the electrics all survived!


So, now I have obviously fitted all the bits and pieces - but - it proved it worked - especially well on 22 volts.


I still have a few bits and pieces to do to her and then she will earn her K7 badge.   I was quite reluctant to put that on - until she had gone onto the plane - and proved herself which she has done. 

https://www.youtube.com/watch?v=pR35atv9fVs

John

[Rich griff]

Good evening chaps


Is there a plan for this boat please ?

[John W E]

hello old Chap


If you have a look over on Sarik hobbies website - they do a plan for Bluebird.   The CD plans which I have don't seem to be available anymore - I am sure I purchased the CD many moons ago from Ebay.
 




John

[Rich griff]

Thanks John, I will go and have a look-see.

[ooyah/2]

Thanks John, I will go and have a look-see.

RICH,
I have a copy of K7 drawing   NO 1462 at Sarik hobbies,  @ £14.50 + postage in very good condition as it was never used to build a K7


If interested you can have it for  £7.50  including postage.


George.

[ooyah/2]

Hi John,
At the very begging  this thread I was able to help Tim with building his K7  ,  Not with the building but with the set up to get his model running.


My K7 is a 12th scale fibre glass model which gives an O/All length of 28", I was advised by Ernie Lazenby not to try and install a fan as the air intakes were too small and the model would be prone to flooding so I went to brushless and Lipo's  2x 2200 in parallel  with the hull fully enclosed.


You can see it running on Y-tube k7:3mp4, on my club pond at Glasgow Richmond MBC I can only get 6-7 sec run but as I live about 25 mls from a bigger pond ( Loch Lomond ) I can get as much water as needed, it can wind up to 45 mph but is inclined to take off just like the full size K7.


I am delighted to see your K 7 running on a fan ,well done and here's to you getting it to run faster.


George.

[John W E]

Hi George and everyone associated with this thread.


When I first set out to build this model, this thread, along with a few other folk namely Ashley Needham, gave me inspiration to build this model.


Ashley, with a couple of people on YouTube videos do prove that a ducted fan can drive a model to some degree of speed.   All I had to basically do was get the bits of jigsaw so to speak and put them together in the correct place.    I used a lot of information gained from this particular thread on building the model for its shape & etc.   For the likes of information on the electric ducted fan's performance etc., I did use a lot of aircraft forums to obtain the data.


So, basically I am a data collector  .


All I did was put the data together to produce my model.   


I am happy with the way she performs at the moment.     I will not be modifying the model/improving it anymore as I am very happy with it the way it is.   The other thing I will be doing is earmarking a longer lake to do a full speed trial.   


So anyone who wants to take the gauntlet up and produce another model of Bluebird with a ducted fan; my advice is keep the model itself extremely light.    I had aimed for a model which weighed about 4lbs or just over (in old English money)     as the thrust from the ducted fan, which I used, was stated as 7.5 lbs thrust at 24 volt.   The best I could manage was 6 3/4 lbs at 22 volts and the model weight actually ended up at 5 lb 6 oz (all up weight).


There's the challenge for someone to carry on with.     I was asked by a Club member would I consider building Crusader model as my next project - Nar - don't think I will.


John

[Circlip]

"I can get as much water as needed, it can wind up to 45 mph but is inclined to take off just like the full size K7."
 

         Hi George, good to see you're still stealing air.  At 45mph how does that scale up to Campbells "Take Off" speed? and how big were the scale ripples on the pond?

  Not many 'Scale' Lake Conistons.

  Regards  Ian.

[ooyah/2]

"I can get as much water as needed, it can wind up to 45 mph but is inclined to take off just like the full size K7."
 

         Hi George, good to see you're still stealing air.  At 45mph how does that scale up to Campbells "Take Off" speed? and how big were the scale ripples on the pond?

  Not many 'Scale' Lake Coniston.

  Regards  Ian.


Hi Ian,
Still standing although it was a near thing,
In December I had a heavy Coviid which was not really cleared before the end of Dec when I contacted  another  virus .
On 3rd of Jan I was admitted to the Glasgow Royal Infirmary  ( GRI)  with severe Pneumonia and was in there for 9 days before being released.
I was doing fine over Feb and March when I had a dizzy turn at the top of the stairs and did a header down and whacked the Acorn at the bottom. on my ribs on the R/H side, fortunately after X-rays there was no breakages or cracked ribs,
June and July left me with bad muscle pains all over which turned out to be Polymyalgia, after seeing the Doc I was put on a Steroid and more or less instantly the pains were gone so now thankfully I am on the mend but still not allowed out on the bike.

I haven't been into the workshop yet where an unfinished Stuart Steam driven boiler feed pump awaits finishing but doing a bit of easy gardening.

Regarding the scale speed of my K7 I don't have the formula to convert this but may be some body has this and would pass it on.

Here is a pic of one of the bays on  Loch Lomond, my photographer caught K7 too far away so may be next time it will be better.

Thanks for the concern

George.

[BESM]

I have just completed a Bluebird here in Massachusetts and have posted a description and first run here

https://www.youtube.com/watch?v=SEzGwatBYZs

Some tuning might get it to exceed the 44 mph I saw on one run

One thing amazed me was that on two occasions it capsized and righted itself at kept going at a good clip

Bruce

[DBS88]

John, the need for speed is addictive, but how fast do you actually need to go? Bruce makes fantastic use of technology to monitor what's actually going on and a very informative video. He recognises where the balance point is, if he is going to try to go faster suggest it moves forwards to avoid the lifting that George describes and experienced, it would be a shame to destroy such a nice model for the sake of a bit more speed.
The builder (Tim) of the model I am fortunate enough to look after wanted to create something that looked the part whilst underway on the water, a super fast top speed was not his aim, I genuinely believe he succeeded. I have been tempted to run a 4s battery instead of a 3s to get an extra 9000rpm and increase the speed of the model. Its already been clocked with a GPS tracker at over 40mph on a couple of space restricted runs, will it go faster with the current set up, maybe. Will the model look any different at 55 to 60 mph? Probably not, will a bigger lake be required yes, will the increased risk to the model be worth it? Only you can decide that. 
Have a close look at these photos, not sure how fast these runs were but they were close to the max, and notice just how close to the edge of lifting the model is already, the tips of the front sponsons are on occasions off the water with only the blades for directional stability left in the water.

[BESM]

Nice pictures - and hard to take as well!
I am going to try and take pictures of my boat at speed to see how it sits.

Someone suggested trimming the rudder height to reduce the drag and I plan to do that as an experiment.The present rudder has almost too much authority.Its blade length is 3.5" with the water port at 1.5" up from the bottom. At first I plan to cut off 1" from the bottom and observe the result. I hesitate to take more off since I don't want to affect the water pickup performance.

Thing is, the boat is plenty quick enough to get you into trouble - you do need quick reactions!

Bruce

[John W E]

hi there, I have just purchased a GPS speed tracker for my model of Bluebird.    Doing a rough calculation using Google maps and the distance travelled and timing it at the lake - I guesstimate - she may be doing just doing under 20 mph but still accelerating.  Making arrangements to use a larger lake so I can let it achieve its top end speed - or at least find out what it is.  I am thinking of another model of the 1930s speed era.


With regard to rudders, the rudder on the Bluebird I have built is scale size, along with the stabilising fin on the stern.  What I have done is set the transmitter up with 2 settings for the rudder on the operated by the switch; first setting switch on - full movement of the servo & rudder.    This is what I use for very slow speeds, setting up ready for the run and then when I set the model off I flick the switch and it restricts the movement of the rudder at a degree or two off centre : the reason for this is that I nearly turned the model over by thinking I could turn it at high speed.   This set up prevents me from doing this.


The other thing is when I cut the power off the fan and the model coasts, which your models will not do (because of propeller drag) I use the rudder switched back to full operation use of the rudder and use it as a brake.

test run 2 - YouTube


running on 14.8 volts

John

[John W E]

Couple of pictures from my build.   Materials used 2mm Lite ply; balsa wood planks and obechi.   The internals of the hull when she was completed were given 3 or 4 coats of Deluxe Sand 'n' Sealer.


When completed the exterior of the hull was coated with 3 coats of Z poxy finishing coat.   No matting or tissue was used.


Then it was just the standard spray painted of filler coat, under coat and then top coat of blue (Ford Electric/Monza Blue.


The speed controller is FlyDragon Lite 140 amps


The ducted fan (EDF) is the Galaxy 8 EDF producing 3400g thrust 24 volt


The motor on the fan is a 3280-KV2200


The batteries are Lipo 11.2 volts - 2 of them that is for a main running.   For trial of the model we used 2 x 7.4 volt lipo batteries giving 14.8 volts.  These were all 500 mAmp.


John

[John W E]

 

[John W E]

sorry all the pictures seem to appear in the wrong 'order' that's my filing system for ya. 

[Circlip]

Even 'Naked' it looks pretty John.


  Regards  Ian.

[John W E]

hi there one and all


A gent from Heaton District Model Boating Club (Andy) has sent me this video which shows us - the mottley crew - testing Bluebird on 14.8 volts.   It's just a very short video - from a different angle to my video - take note how she accelerates on 14.8 volts.


Pity Andy doesn't have one of her running on 22 volts .


John


Bluebird run 2 - YouTube

[ooyah/2]

HI JOHN


P.M. sent