Second test was slightly better, using the aluminium spiral cut universal which came with the jet unit. As you can probably hear, it was horribly out of balance (even with cable ties to reduce it). It was not even drilled centrally and the spiral is right hand when it should be left hand, (like a spring twisted against the wind, it wants to deform). Slight improvement in speed on the first test (no slip this time) but the noise was horrendous.
Have pulled the jet apart and found that the 3 blade prop is around 1 mm too small for the hole, causing cavitation (see loads of bubbles in the jet stream) which is causing loss of thrust. The prop is the wrong type as well, with rounded blades, so I have modified a larger prop with more pitch to fit snugly in the unit to hopefully increase thrust. The shaft is also wrong, with a flat cut almost half the diam and carrying on through the bearing, allowing the grease to fly out.
I actually saw a Chinese site on Al Expr stating that "some dimensions on the product may be different due to the number of machines and operators involved in its' manufacture," SERIOUSLY!!??? their quality control must be utter crap and the operators not skilled enough to eat their lunch😐 Why bother having a dimension at all?? Little wonder nothing fits properly.
Unfortunately, most model shops sell the very same stuff, unless you want to shell out muchos dolleros for European stuff. I have just ordered some 4mm silver steel to make a new shaft, so a coupling or silicone tube will fit better. Also ordered some solid connectors to try. Vibration is wasted energy so it needs to be eliminated. Hopefully the mods will improve things and allow the motor to run on 4s rater than 3s. Worked out that the motor is only 1200KV, so it's only doing around 13,000 rpm under load. Probably will need around
18,000 rpm for proper performance. Onwards and upwards (or forwards as the case may be.😁)
Sorry about the blurry vid again, but my camera lens is knackered.
Weather was perfect tonight for a test, so I did the 15km trip out to the Gulf harbour pond (most weed free pond) to throw the boat in. After a thorough under water hull inspection from the marine department, she was off. Everything worked ok except the silicone drive tube which had become enlarged due to soaking in the grease coming out the front of the jet shaft. It was slipping badly and probably losing about 60% of its' thrust. Manoeuvrability is excellent but reverse leaves a bit to be be desired. Steering in reverse is perfect but the thrust is not going forwards enough from the bucket. Might have to build in some nozzles to direct it better.
Smoke air and water are working as well as can be expected, (smoke is a bit wafty, but with too much air introduced it will disappear as it gets thinned out too much to see) I was not expecting miracles as this was a bit of an experiment (modified cheap jet unit with unknown abilities) but at least it shows promise😁. If I can find a coupling which is concentric it will solve the drive problem.
Trouble is, the Chinese insist on making a 4mm shaft, 4.95 (or whatever) which is useless for balance in a 4mm ID bearing for example. Fine for cars, but no good for boats or planes due to balance requirements (it's a mission trying to balance plane props due to this thinking,- they do it with everything) shafts for electric motors are a nightmare at times as the play they build in, can ruin an otherwise good motor. I might have to buy a flexible rubber/nylon universal or a collet style( preferable as these take up any undersize on shafts) to fix it. They included a spiral alloy one with the jet unit which is as loose as a rooster in a sock, and only good for slower things like 3D printers etc. One of these days they will learn how to machine things to fit.😐
Seemed to work a whole lot better in the tank for some reason Martin. Possibly due to the coupling slipping, (the squealing is it slipping) Just a bit of silicone fuel tube. I use it on all the boats as it's quiet, self aligning, and lets go if your prop gets jammed by weed. Problem is with the jet, it has a flat on the shaft for some reason which doesn't help the tube grip, and lets grease in causing slippage. I'll sort it eventually,- didn't expect miracles first time out (same with planes) - Almost always some small initial problems.
Motor should be spinning at 15,000 rpm with a 3 cell, but performance is not matching that, obviously,- just piddling along😁 Mind you, I used to cruise like that in the full sized boat, as the Zodiac motor used to suck gas like nothing at 20 knots plus, (gallons per mile, not miles per gallon!)
Thor is a freelance design of a multicat vessel. These rather unusual ships are real workhorses, designed as a work platform, often with a hiab crane. The square hull gives a large flat deck, with plenty of open space for a work area or for deck cargo. The design also enables the vessel to be used as a tugboat, either pushing or towing and are often equipped with large deck winches and strong points for this purpose. A true Swiss army knife of the sea, able to adapt to most roles, some even have additional internal fuel tanks for refuelling other vessels.
More info found on -
Model Boats Website - BoatClubs & Lakes - Buxton Model Boat Club
Seen here at Buxton is - 'Ellipsis' an International One Metre Class yacht .
Built from lines drawings purchased from the designer Frank Russell.
Neville hand laminated the hull in epoxy glass, and the fin and rudder in epoxy carbon. Hull finished in cellulose paint.
Information provided by Neville Black.
Model Slipway Model - "Maggie M" is a Fishing Trawler
Scale 1:32 L. 850 mm B. 255 mm Approx. 10 kg.
Built in 1990 by Campbelltown Shipbuilders Ltd (Scotland) MAGGIE M operates out of Scarborough harbour in Yorkshire, United Kingdom. The vessel is designed for twin-rig trawling and the aluminium shelter-deck is a cover over the fish processing room.
You're getting around a bit arencha Ron 👍
Tug looks kinda Springerish.
A pusher tug for barges or logs?
😎
Turns out she's a 'Puller' 😉 A 'Pushmepullu' 😁 http://www.tugboatinformation.com/tug.cfm?id=3524
Cheers, Doug 😎
Finally, had a decent day (if you can call calm but fully overcast decent) and managed a try-out of the ST. Unfortunately had the pleasure of some yappy kid asking a thousand stupid questions, then his grandfather started, while I was trying to set it up. Got so distracted I ended up breaking the mast while trying to grab the boat and answer rapid fire questions. Trying to do a video and the kid's yelling behind me, and the grandfather just let him carry on.??😠 Don't mind kids being interested at all, but some are just a pain in the 'transom'
Anyhow, enough grumpy old man stuff, -boat went pretty much perfectly and is plenty fast enough, and also very economical on the batteries, (Vid was twice as long before editing) and when I stopped they were still at 3.9v/ cell (they are only 2200MAh 2s ) and were only 4.1 at the start. All in all, distractions and a bit of mast damage aside, I'm quite happy with it, (did hit the jetty at a 20deg angle at 2/3 throttle while taking photos, - going for that last shot -😀 bounced off without a mark, - lucky the jetty piles are slimy and I build tanks !)
I get easily confused in my old age Doug😐 I've got 2 cars, an auto and a manual, - I've noticed lately, when I shift to P for pass there are funny noises, (noticed the same when shifting to R for race) and in the manual, why does it make funny noises when I pull the stick back to drive off?😮
Confused😐
Finally managed to get this to come out the right way up on You Tube (didn't like MP4,- came out upside down). Running the 2 boats from an HK 6ch 2.4 radio (slight crash and jostling by the Maiami at the start) . You'll get sick of it in a few minutes and fall asleep but I've put it up anyhow😁 If this doesn't make you seasick, nothing will!😊 Hit a Koi carp (Chinese sub) at 3.01!
"Koi carp (Chinese sub)"
Er ... that's the JDF, Japanese Defence Force sub JB.
Didn't get seasick, but it did 'make me eyes go funny' 🤓
This can never work for more than a minute or two cos you'd need to have absolutely identical performance of ESCs, motors and rudders (perhaps also hull forms) in both boats.
I tried it once with my destroyer and Sea Scout - no chance!
Had more luck 'escorting' a same scale (1/72) Flower Class corvette around the lake in the Olympia Park, Munich ca 3 decades ago 😉
😎
This vid is cut down from around 20 mins Doug. Each boat is totally independent of the other as one is on the left stick using one RX (elevator and rudder channels) and the other on the right stick using a second RX (throttle and aileron channels)
I think everyone has the idea that they are on the same stick? The eyes do go a bit wonky as the camera is only a small keychain camera (pre Go Pro days) which we used to mount on planes etc, and the boat movements are quick.
You can always change the playback speed (on the left of the You Tube logo)
JB PS I'm sure I saw a red star on that carp!
Liking dat man.
Congrats Rasta Lieutenant.
Martin555.