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[Jerry Hill]

I've thought about it a little, bought a few for the purpose, and continued to look at them in the packaging since mostly to be honest. I baulk at the idea when it comes to lubrication mostly, with concerns about what power can be put through them. There's a seed of an idea in there somewhere though.

[Tim_M]

Hi Jerry,
Yes, but you are talking SERIOUS horsepower in your boats! My guess is that some of the off-road competitive hardware would handle the average fast electric. You, my friend, would have to knock something up. Well within your capability, I reckon!

[Jerry Hill]

I've taken a peek at the shafts I have properly Tim and it turns out none of them are CV joints. As much as they look like them mine are differently made universal joints with the problem Mr Hooke found with them. So a gimbal arrangement. Do you know of something different?

To be honest if it were looked into closely the fact that IC engines are not constant velocity themselves would have to be taken into account,  that element is already more demanding on the power train needing tougher stuff than a same power electric motor, where their margin of velocity shift is so small.

So, if we assume an electric, whatever the power, two universal joints with appropriate positioning will result in a constant velocity output but with the intermediate shaft being the only potential source of vibration, if a true CV joint isn't out there.

I hope there is a solution, I'm not a lover of flexible shafts.

[w3bby]

Check out the wire drives that are making waves.... Even being used for ic petrol nowadays (not exactly similar but the idea is the same).

[Tim_M]

( I've seen some CVs on the net that look like proper jobs and plenty more that are definitely not. Oh well; I need to get this thread back on track before I get told off  )


This week has seen progress on some of the detail work. There's no particular build order at the moment; I can just do what takes my fancy on a given day. I made the little box for the Rx. How many clamps can you get on a 50 x 70 mm box? Quite a lot, as it turns out  . I tidied up the joint between the cowl and the hull and, having got a nice sharp edge on the cowl, I decided to give it another layer of glass to protect it. That went well and it's looking pretty smooth now. Plenty of time for me to ruin that when I start painting. I've also formed the fillet between the lower cowl and the deck. A little more work to do there.


The nose of Bluebird is like the Mona Lisa's smile - enigmatic. I've looked at dozens, perhaps hundreds of photos and in every one the nose looks different. Over the weeks, I have gradually worked on the nose until I ended up with a pleasing shape. Unfortunately, when I looked again yesterday that pleasing shape was nothing like the original. Miles out. I'm not a scale fanatic but there was only one thing for it. Rhinoplasty! I slapped on some 2 part filler and set about reshaping the bow. I've now ended up with a shape that looks pretty close to the original, perhaps closer to the replica. Did I get it right? Haven't got a clue to be honest. It looks right to me but then it looks completely different in the photos  . Anyway, that's how it's staying because I'm starting to break through to fresh air - and my fingers are worn out. I'm sure it will look OK once the badge goes on.


For the benefit of anyone who's contemplating this build, I finally worked out the geometry of the nose (I think) and this is how you create it:


To start with, forget about the radius between the deck and the sides. That comes later. Form the longitudinal curve of the deck first. The sides are flat. Starting from around the forward boom box, the sides get an increasing chamfer until they meet at the bow. At this point, you should see a characteristic curved V form where the sides and deck meet. My photo was at slightly the wrong angle; the chamfer is steeper than it looks. Once you are happy with the V shape, add the radius, starting from the kink in the deck and increasing uniformly to the bow, where the radii from the two sides will meet. Then it's down to your own interpretation, eyes and patience. Worked for me, anyway. BTW, does anybody want about half a pound of used filler? Very low mileage.


Next step is to clean up and glass the hull. I'm not going to do that today as I've had enough and I'll only mess it up!

[Tim_M]

Nothing to see here.............
Just a verbal check-in this week because the boat looks exactly as it did last week. There have, however been some changes. The hull and cowl are glassed, sanded and are pretty much ready to paint, which came as something of a surprise to me. I had allocated a couple of weekends for the sanding. In the event it took about an hour to do the glass coat (bottom one evening, the rest the following night) and just an hour to sand it. There is just a slight suggestion of 'weave' in the surface when the light catches it right. That seems good to me - the surfaces are flat and I haven't taken all the glass off. But it looks as if I've done nothing!


I fought long and hard against using glass but I'm glad I gave in in the end. I'm surprised how easy a process it turned out to be and the results are very pleasing. Hopefully no more corner joints popping open on this model.  .


Photos will follow when there is something to show. Meanwhile, you might want to check out my rowing machine post in R&D. 

[Tim_M]

Slow but steady progress. All the major bits are now made and this week saw them coming together for the first time. I reckon that merits a photo  . Last couple of weeks I have been working on the boom covers. They seemed to take an extraordinary amount of time for quite small pieces - especially as it took two attempts to get the rear ones half decent. I lost two weekends along the way too. We've had my wife's mother staying for the summer and last weekend was taken over by a big 'going away' party. This weekend was a 3 a.m. start to get her to Heathrow. Unfortunately, she arrived home at just the same time as Typhoon Lando. Not a nice trick to play on a first-time traveller but she got there in one piece so all's well.


Back to the boat. Everything is glassed. Next job is to work on the fillets where the front boom joins. Remember, with this model the booms get fitted after painting so I need to make a decent job of the joint. Then lots of wet sanding and start throwing paint at it. The reports will be a bit slow coming as I have to take my time now; everything from here on will show on the finished model. The woodwork has gone well (far beyond my expectations) but painting has always been my weak point. Steady as she goes! is the order of the day.

[Jerry Hill]

Looking good.


I seem to be a bit of a nay sayer on this one, but I would not wet sand it yet. I don't know what paint you're planning to use, but even a small beach of the glassing could result in a whole load of back pedalling. I would get through the priming process dry first. Once you have a reliable full coating which does not breach dry sanding, apply a further coat and wet sand it from there. All wet sanding offers is waste clearance to reduce abrasive clogging, not such a big issue on a model sized painting project.

[Tim_M]

Thanks for the advice Jerry. I'll just take off the lumps where I was clumsy with the resin and start to built up rather than take off. I'm looking forward to/dreading the paint job in equal measure!

[Stavros]

I DONT advocate wet sanding at all this is because all primer is porus so WHY introduce Damp into your paint


Dave

[Tim_M]

Contrary to what you might think, I have been beavering away on K7 in every spare moment.


I guess every project reaches a point when you think "My goodness; why on earth did I every undertake such an endeavour?" (or less family-friendly words to that effect). Hopefully, this project has just passed through that stage. Me vs the boom covers. Those four little parts took a ridiculous amount of time to get half-decent. I don't need to tell anyone on this forum how difficult it is to form those fillets. Filler on, filler off, on-off, on-off. Same with the paint. Getting them right without cutting into the flat parts is so tricky! They are not perfect but, as my mum used to say "A blind man would be glad to see it." (She had a few more flowery sayings too....). A little more paint and they'll do for me. (I'm losing the will to live!)


Speaking of paint........... I had already wet-sanded the hull before I got advice. I was very careful not to cut into the glass and it turned out OK. So, why the multi-coloured hull? I started off using UPol #5 Hi build primer. I've used it before and found it very good. However, after a few coats on the boom covers and one coat on the hull I had an empty can and a whole lot of painted newspaper. At twelve and a half quid a can, I needed a plan B. I decided to used a brushing primer, at least for the first coats. Following the instructions on the can, I used a generously loaded brush and laid the paint on in one bold stroke. Non of that brushing out and laying off malarky - it dries too quickly. My kind of painting    It looks pretty grim at first but after an hour or so, the brush marks go away. Most importantly, the paint is on the model, not all over the bench.


I struggled with dry sanding at first because the paper clogged instantly. Discovered I needed a much lighter touch. Sorted.

I have started using the airbrush now. I have a lot to learn about that joker!. Struggled at first but found the paint needs to be much thinner than I imagined. I then noticed some splodges coming through. Water! I had chosen today (wet and wild) to try spraying. Twit! [size=78%]   [/size]The water was condensing in the nozzle as the air expanded and cooled. Not a disaster but a light rub down and more coats required. I need to work on a dry day (I wonder if I can get a cheap air dryer?). I also need to knock up some sort of spray booth before I do the hull. I have a proper mask but I think my garage may end up completely light grey. Even at this stage, I can control an airbrush much better than a spray can. Looking hopeful.

A while back I knocked up a dummy engine. I was toying with an empty beer can and a bottle top (like you do.....). I noticed that the reflection of the top gave a pretty good impression of looking up the dangerous end of a jet engine when the light caught it right. (Come to think of it, both end are somewhat dangerous if you get too close......) Very hard to catch it on camera - you'll have to take my word for it. Turned out that a mini coke can was the perfect size. Just cut it up with a pair of scissors, reversed the bottom and put it back together with a mallet. I kept the rolled edge of the can intact in the interests of retaining all my fingers in the future. (I may have to build a larger scale model at some point so I can use a proper beer can. Preparing your raw materials is half the battle......)It's just a case of soldiering on with the painting for now (weather permitting). One day I will get round to some fitting out. Who knows? One day this model may even get wet!

[Jerry Hill]

What size airbrush do you have? A model of this size is not really airbrush territory.
Moisture usually forms upstream of an air tool, and the solution is an inline moisture trap or water separator. Many of these are mounted on the compressor, but it's better to have a length of airline between the compressor and the trap to allow the water vapour to condense fully before being separated. Basically the cooler airline acts as a condenser. Bear in mind the airline will probably still have moisture in it, so it'll need drying if reused post separator.

Some airbrushes will not pass anything with a viscosity higher than milk, really fine ones struggle even with that. Upping the air pressure can force atomisation, but this causes many other problems. A good indicator is the comments of spray cans. Spray some into a lid and check it's viscosity, that's about the upper limit of any spraygun that could be called an airbrush.

For a way of generating a smooth transition from radius to flat try rubbing off the flat into the radius at up to 45 degrees. Helps to avoid those grooves.

If your abrasives are clogging too easily it may not be coarse enough a grade.

[Tim_M]

Long time no see..............


I got sidetracked (side swiped?) The second Tuesday in November (I remember it well) I came down to find the entire contents of my central heating system distributed all over the ground floor - kitchen, dining room, lounge and hall. The 30+ year-old boiler had finally rotted out. Time to get the men in. Needless to say, they couldn't put a new boiler where the old  open-flue one had been so after a major rearrangement (boiler upstairs) I was left with a nice new heating system and a wrecked kitchen. The floor-up refurbishment took me right through Christmas. Along the way, I had to replace my drill and router and then the dishwasher died. As I said to Mrs M, everything in this house is getting old and worn out. She just looked me up and down and walked off. Revenge is pending.


It was February before I could even think about modelling but at long last Bluebird is ...................................... Grey.


It took ages. I could blame the materials, the tools, the weather or the light but the truth is I am rubbish at painting. I tried various spray cans to no avail. I ended up using an airbrush and Halfords grey primer (cellulose based). I agree that an airbrush is not the ideal weapon for a model of this size but I found by a process of trial and error (mainly the latter) that I could get the paint consistency and setting right to allow me to walk the fine line between getting the surface wet and getting runs. I looked at buying a mini spray gun but my compressor is not powerful enough. I lost count of how many coats I put on. I guess it's the equivalent of about two good coats by a competent sprayer. Whatever. I have had to take a reality check. The surface is not perfect but I'm not building a museum-quality model here (I couldn't). It's a toy and it will no doubt pick up a few dings and scratches along the way (going on my past driving record). If I try too hard, this boat will never hit the water.


I learned one important lesson the hard way. Mix your paint properly! Preparing the paint for what was to be the last coat, I found a lot of sludge in the bottom of the tin. I mixed it in and thinned the paint for spraying. Next day it had dried like crazy paving and had to come off. I guess what happened was that the sludge contained all the heavy solids but not enough of the binders and other chemicals to make the paint work properly. Adding thinners just made it thinner. I started again with a fresh tin of paint and made a swizzle stick to stir it with the electric drill. You have been warned 


I have added some panel lines; they really bring the model to life (though they don't show well in the photos. Rivets heads? No chance!


Next step is to get some colour on. I'm using water-based acrylic; it's cheap and readily available. I am optimistic. I tried one coat on the boom covers and I was amazed how well it covers with just one coat. Of course, it's matt but I intend to blow a coat of water based varnish over the top once the decals are fitted (tried it on some scrap and it looks OK). Then it's on to assembly and fit-out. Actually, that's not quit true. The next stage will be to make a stand. Once I start fitting out, there will be all sorts of stuff hanging down below the nice, convenient flat bottom. She has to go up on the blocks.


With Easter on the way there is a chance of progress!

[Martin (Admin)]

Nice finish!

[Tim_M]

And now it's blue......... (and decorated)
Many coats of acrylic and then I started to apply water-based varnish. That didn't work very well; no real shine. I resorted to 'full fat' polyurethane (Blackfriars gloss), slightly thinned. And that worked much better. The decals proved tricky. I bought the paper years ago for something different and it worked well. The prints looked fine but.................. the ink wasn't waterproof! (Cheap 'compatible' cartridges). I tried the sheet that I had printed at work on a posh laser. Also not waterproof. I wasn't about to rush out and buy 'genuine' cartridges (who can afford those these days? You can buy a whole printer for the same price!) so I tried blowing a light coat of Humbrol varnish (bought at the same time as the paper) over the sheet first. Worked fine. Not sure if the Rolls Royce badge existed on the original but it looks pretty cool.


Somebody take Stavros off to a darkened room - he's not going to like this bit. I was trawling the net looking for a replacement needle/nozzle for my gravity fed airbrush; I had wrecked it learning how to dismantle an airbrush. A came across a '0.3 mm airbrush, gravity fed spray gun, 100ml cup' on ebay, UK stock. (Item ID: 151716939279 I was tempted. Turns out this thing can handle quite thick paint and (even better) varnish. Any good? The only problem, apart from the fact it comes with a full-size airline bayonet, is that my tiny airbrush compressor struggles to keep up with it. Spraying in quite short sessions and allowing the pressure to rebuild in the tank, you can get away with it. It certainly worked better on the larger parts than an airbrush. An the cost? £7.50 plus £1 P&P. That's why I was tempted! With a large compressor, I reckon it would be really good  - but then if you have a large compressor, you probably already have a good  spray gun.


The finish on Bluebird is far from perfect but it's good enough for me. I know I will only make it worse if I try to make it better. The next stage is to build a stand then on with the fit-out and detailing. Mrs M is on the other side of the world at the moment so she doesn't know how long I am spending in the garage 


Oh, I forgot to mention that I found the perfect pilot. Blue overalls, goggles and even a teddy. 

[Tim_M]

I don't know what the splodges are in the close up of the nose - they don't show in real life!

[Tim_M]

Looking quite purposeful now. I had planned a week of intensive modelling but Storm Katie had other ideas. Three days of outdoor repairs................


Question:
I noticed the LiPo is looking a bit strange after the winter (I left it with a 'storage charge'). There's a bit of a bulge on one side that seems to be a gas bubble. Anybody seen this before?
Plan A is to charge it up again outdoors. If it blows, it blows. Then I think I will make some sort of test rig and put it under load to see what happens - unless somebody tells me I'm on a hiding to nothing. I'm reluctant to throw it away as it's only run for about an hour but, on the other hand, I don't want to see Bluebird explode.


Meanwhile I have a heap of small bits to make and fit.

[Tim_M]

A small step forward; the shaft tube is fitted. There are snug fitting pins in each end so the strut and motor are aligned to the tube. The skeg/centre board was slotted into place and then the motor and strut fitted to the pins. Glue was applied to the motor mount and the whole lot was then adjusted to get the prop height right and the motor nice and low.  A single bolt locks the centre board in place. All the bolt holes had silicon applied before assembly and the 'formed in place silicone grommet' (blob of sealer) made. When this lot is all dry, I have to cut the tube at both end to remove the pinned sections. Finally, I will do a leak test and once everything is OK the rear section will be sheeted in and sealed for life.


The finish on the bottom? Blue Bird meets Blue Peter. Stainless steel effect fablon! According to the manufacturer, it's waterproof and has a guarantee of three years out of doors. Well, it looks pretty good and saved an awful lot of masking and painting. The underlying surface is fully waterproof anyway; it won't be the end of the world if it peels off. Not sure I will use it on the sponsons as the area is quite small.


BTW, I decided to play it safe with the battery and ordered a new one. I may still investigate the old one but this way if it works it's a bonus rather than being tempted to push my luck and run with it.

[Tim_M]

Just Add Water.................


That's it, for better or worse. Just need to charge the battery and sort out the channels on the Rx before sealing the box (it's held it with velcro), tape down the hatch and throw it in the lake. Now is a good time to get some pictures. Those of you who have followed the build log will know that thanks to my (lack of) driving skills, this may be the last time we see Bluebird in one piece. I shall wait for a dead calm day and take it easy.    Oh, I do have to build a transport cradle. The stand I used for building is so heavy, I'll slip a disc if I try to put it in the car.


On the whole, I'm pleased with the end result. The paint job is not good but it is about ten time better than I hoped to achieve. Scale? I don't think anybody would be in any doubt as to what the model represents. The front booms are a bit chubby (because of the tube I used inside) and the 'double curved' scoops in the hull are definitely a figment of my imagination - they do look nice though! Of course, the sponsons are not scale and there's all that stuff hanging off the back. Unavoidable, I'm afraid. In retrospect, I should have ditched the prop strut and used a solid shaft. Something went a bit awry and I noticed the sponson edges are set about 20mm below the hull floor. It should have been more like 35mm. My adjustable prop design came in handy sooner than I expected. Having sheeted in the rear deck, I promptly had to cut an access panel in it, raise the prop to match the sponsons and fit a cover (with silicone). I'm not convinced the hull will ride clear of the water yet but we'll see. If need be, it will be easy to add some running shoes.


You can see the battery tucks away right up front. The CG comes out just about right with this arrangement, maybe a tad too far back. Again, we'll see. The rudder has twin water scoops and the feeds for the motor and ESC are kept separate. I also split the feed to the ESC and have two discharge pipes (plus another for the motor). The little funnel is where the antenna sits and I've put the main switch through the hatch cover. I'm only a mile from the lake and will probably seal everything down before setting off from home.


The flotation test was OK. I didn't run the prop as the inhabitants of the pond are very inquisitive. I have better things to do on a Saturday than clean minced fish off the side of the garage...........


Once we get a good day, it's off to the lake with camera (and 'Rescue 1')  ready.

[Captain fizz]

I say Tim, that all looks rather good.
Looking forward to your test runs.


Simon.

[Tim_M]

At long last, the elusive combination of good weather and spare time.


The maiden voyage turned out well. Low speed steering is a bit iffy (won't turn right for some reason) but once she starts to plane the steering is very good. She rises up onto the plane easily and rapidly gathers speed. Not sure how fast it will go when I really open it up - my nerves were in tatters after the medium-speed runs.


I have uploaded a rough video so you can at least share the first run. Note the afterburner in action at the end  . Nipper couldn't keep up with the higher speed trials but credit where it's due - he did manage to get some video of a fast-moving object ans a cracking 'still'.


https://youtu.be/vqWwuV4NOec

[ooyah/2]

Hi Tim,

Your K7 looks the part and I don't think you will have any trouble when you apply full throttle, just keep your concentration at top level, if anybody speaks to you when you are sailing K7 just snap the throttle shut and ask the person not to talk to you when you have the boat under control as it only breaks your concentration.

In my early days as I was going up my lake at full throttle a guy asked a question and I tried to answer him only to smack my K7 into the concrete wall at the end of the lake doing 40 m.p.h. so you can imagine the damage and my answer to him !!!!!!!!!

Great job it was worth the efforts maybe you will manage to get on a lake which is larger than yours and have no Geese for company and you can really let her go..

George.

[Tim_M]

Hi George,
I think you're right; I will be able to open her up a bit more once I get used to it. It just a little unnerving seeing all that work flying on the tips of the sponsons and trying to remember which is left and right as it goes past  . This model came out a good half kg less than the first, which helps. The success of the first run is, of course, due in no small part to all the advice you passed on based on your own experience. I appreciate that a lot!


Unfortunately, there is only one boating lake on the IOW and somebody ruined that by sticking an island in the middle of it as a bird sanctuary. There is a picturesque natural lake a few miles away but access is very poor. I think I would have to be very confident in the model before I let it go there. There's always the river Medina, but a safety boat would be essential. Never mind; I enjoy watching K7 as it transitions from floating to flying. Once it's flying, it tends to go out of sight anyway! I hope to get some good video footage over the summer and will post again.


Rgds,

[ooyah/2]

Hi Tim,

I would be reluctant to try the river, as you know rivers run out to the sea so I would stick to lakes.
 With the engine bay top fixed on over a sealed engine compartment do you have any water ingress ?

Don't think left and right, think Port and Starboard , it becomes easier to remember.

I find that my K7 responds better to Starboard as the rudder is more to Port and the wash from the prop helps a great deal, but on no account try to turn K7 at high speeds.

You will get used to the speed , if you crash it it's 2- off the belt for you.

Take care

George. 

[ballastanksian]

She looks very real Tim. You have sorted the balance issues out and probably better than the real thing.

Mind you, with a Minion driving, you may have to wrestle the controls back on occasion!