That sound better with a 5 mm shaft. But still be sure to support the shaft under the boat and if possible also under the shaft inside the boat. This way you shouldn't have any trouble with vibration though the shaft to loosen it.
Hi Graham Now we can see the actual prop shaft and motor it is clear that the shaft is not supported inside the hull close to the coupling. At the high revs your motor achieves I am not surprised you have had problems. I do agree with all the comments and help you have been offered and agree a 5mm shaft would help as well as a different motor. I use 3 blade brass props with brushless and have no problems but do keep the prop size to a diameter no greater than the motor diameter, as Mark advises. It's difficult to see how much space is in the hull to allow the motor coupling and shaft to be closer, but if you are replacing the shaft it may be a good time to reposition the motor and the shaft with the prop attached to a slightly different angle. This will mean opening the slot and perhaps enlarging the outside skeg but you can easily repair any damage with plastic padding to make good. Even if you keep the existing arrangement I suggest you provide support for the prop shaft close to the bearing as I suspect this is where you have experienced the problem with the vibration. A simple 2" block of wood attached to the keel and shaft would suffice. Model looks very good and I look forward to seeing some on water shots.
HI Graham. Every picture tells a story!!! The motor is definitely wrong, its designed for racing, low torque, mega revs, not for scale boats. What diameter is the shaft tube??? looks thin??? did the prop shear in the water?? would explain the vibration and damage to the shaft mountings, try a Raboesch shaft, with a ballrace at the motor end, great quality, also they do a huge range of props, google the name there site will come up. Mark
Hi traiderman I am no expert. dont forget, as pmdent highlights, you you multiply the KV by the volts of the supply to get the RPM of the prop. so you can play with the volts supplied or the Kv of the motor or both. regarding the vibration, have you supported the outer end of the shaft? if the shaft leaves the hull and has a good amount of unsupported shaft the end of the shaft effectively will scribe a circle. At the speed the shaft is turning and with the pressure on the prop this may cause your vibration. Richard
Traderman - whilst I am not an expert ( I am currently trying to decide what brushless combo to fit to a 34" RAF Crash tender) - clearly your motor is turing your prop shaft way to fast. With your motor spec of 3180 kV and a 14.7 V Lipo - your motor will be trying to turn your shaft at a speed of somewhere in the order of 45,000 RPM !! Firstly your prop shaft may not be rated for anything like this speed and secondly any slight mis alignment will likely be generating significant vibration - enough to cause your problem- have you noticed any? As to motor power - the motor may not be too powerful - but certainly dropping to a lower kV motor say 1100 and reducing the Lipo voltage to a 11 or even 7 volt system might be the right answer......but as I am finding its all a bit suck it and see... Peter
Many thanks Dave and all. The reason I think it was a kit is because of the superstructure and deck detailing which you cannot see on my photos. All of the window frames have raised rivets around them and the deck has deck raised deck strips. As a modeller I know that these can be recreated but they look too perfectly spaced, etc. Many thanks for looking through your back catalogues Dave. Terry was very helpful and sent me quite a bit of information - he is a font of knowledge. My boat is well used at our pond at Eastrop, Basingstoke where I am the Secretary and Treasurer of the model boat club. Every couple of years I do have to give the hull a rub down and re-spray as being made from balsa and when running fast, the vibration does tend to crack the hull along the panel joint lines, but it is an easy fix and I try not to abuse it as it is precious to me.
I am building from scratch a 35" Mini Momo and looking at the hardware required for the stern. Is there any great advantage to having a Z Type Rudder / Strut Assembly rather than simply having a Stinger and the separate rudder? To me they look like they could be a source of vibration or potential problems as they do not appear to be fixed to the stern at the location of the rudder. Thanks
Hi all I have located an 850 motor and mount at Howes Models in Kiddlington not too far from where I live in Malmesbury, for £22.50 however the prop shaft is 4BA, the coupling is not a problem as I can get the insert for the larger motor to fit the existing red coupling, but I can only seem to find 4mm 40 or 45mm propellers which are a fraction bigger than the 4BA which I know will screw on but they would have a bit of a wobble on the threads and could give me an out of balance vibration, apart from drilling out the old propshaft assy and fitting a new 4mm one what else can I do? or does anyone have a old 4BA prop they can let me have?
[Score: 8/10] 46" Aero kits Sea Queen Single Propellor (2 Blade X Type 45mm) Direct Drive to a 3650 watercooled (2 Blade X Type) Powered by Lead Acid (12v) 7Amp/h Batteries Controlled Through Hobby wing 100 amp w/c (100Amps) ESC - Comments: I felt the need to build something large from scratch having built Sea Nymph Sea Rover aero kits Swordsman kit. Many GRP based I/C powered before converting many of them to Brushless power. In Feb 2017 I bought plans from ebay in readiness for a family trip to Wales. My brother in law has a well kitted workshop in which he produced Sailing dingy kits before retiring. The aim was to produce this boat for the least possible cost. Thankfully there are lots of ply off cuts in Wales plus an 8x5 sheet of 1.5mm so I set about making my own kit during the time I was there. The motor was to be a Marx Decaperm selected from my bits box which I chose to set up using the geared drive. On the first launch performance was lacking to say the least so the motor mount was adjusted to direct drive but alas performance was not much better then everything stopped. The wires on the commutator had become unsolder end a common problem apparently I've now fitted a 3650 brushless stolen from an early attempt of a Huntsman 31 built for my Grand daughter which had replaced the Graupner 600, she is now 19 and interested in other things beginning with B. Having fitted the brushless a lot of vibration was experienced his was traced to a misaligned coupling,next outing will be with a huco type of fitting just to check it out roll on Thursday.
Just spent a few hours fitting brushless motor to seabreacher....and 150amp esc ...problem working at these high motor speeds is vibration and motor has actually bent the driveshaft which is brass 6 mm ...next step is new shaft of steel....
Paul - luckily I have a new shaft as purchased one the other as Dave said about about making sure it true before fitting due to vibration issues later on if it wasn't true. Doug - I'm going to go for your's and Dave suggestion of fitting a fillet as to be honest it sounds easier and like Paul says its underwater so wont be seen and if it ever gets in the water wouldn't want to lose it on first trip out😁😁😁
Neil, the suggestions about prop support are all valid, just different takes on things. I would (if you intend to repaint the hull) sand off to key, or prime the old paint prior to installing the shaft, as it will be easier to repaint and prep. Question, sorry if I missed this, is that a new shaft with new bearings? If not get new from shg marine (they are at the Blackpool, show, and the midlands engineering show if you can get to either, I'm not sure where you are?) they are dirt cheap, called aceteal or something similar, they water lubricate, and cost about £2 each. Roll the inner shaft on a piece of glass or a mirror, this will tell you if its bent, any sign of this, get a new one, or you might have alignment and vibration issues. (glass is totally flat! there's a free tip to test you prop shafts ha ha !!👍) same can be bought from shg, and get stainless. Back to the support, the thing Dave mentions is a piece of wood that fits between the hull, and the shaft. The shaft is then epoxied to this, giving support, but it wont be true to original. You have the original support, so remodel this to fit your new angle. If you use any bolts etc to secure, use stainless so they don't rust. Once painted, it will be hidden, and its underneath anyway so cant be seen. It will need to be tight to the outershaft, once positioned, you could solder, as they are both brass, and either feed into the hull bend over and epoxy, or screw as per original. Here is my big fireboat, its twin, but the concept is the same, the support came into the hull, and on this example, I put a brass pin through, and epoxied it all
Thanks both Doug and Dave I do have a couple of different mounts which were purchased to try and get round my sticky motor which initially proved to the glue holding the shaft had failed causing vibration and the old diesel mount causing misalignment. I have just recently even purchased a plastic type mount like the one you have Doug😉 Should have removed the mount when you suggested it a year ago Dave but a little scared now I can start a fresh. Now thats done and new lease of life should see me busy at the weekend. Little concerned on the hungry and smelly motor but like the idea of a Lipo with Tamiya connector will have a look for those later. Was a little worried about drilling through but like the idea of dowel and sand paper nice and easy I think until I get bored and then probably resort to the drill lol. Thanks for all the advice and the confidence you guys give. Ill update my year old blog with progress over the next couple of weeks.😁😁
Some info. on radar, armament and wartime mods! 'Ya pays ya money and yer takes yer choice'! 😎 "Armament, electronics and protection The main armament of the Illustrious class consisted of sixteen quick-firing (QF) 4.5-inch (110 mm) dual-purpose guns in eight twin-gun turrets, four in sponsons on each side of the hull. The roofs of the gun turrets protruded above the level of the flight deck to allow them to fire across the deck at high elevations. The gun had a maximum range of 20,760 yards (18,980 m). Her light anti-aircraft defences included six octuple mounts for QF 2-pounder ("pom-pom") anti-aircraft (AA) guns, two each fore and aft of the island and two in sponsons on the port side of the hull. The 2-pounder gun had a maximum range of 6,800 yards (6,200 m). The completion of Illustrious was delayed two months to fit her with a Type 79Z early-warning radar; she was the first aircraft carrier in the world to be fitted with radar before completion. This version of the radar had separate transmitting and receiving antennas which required a new mainmast to be added to the aft end of the island to mount the transmitter. The Illustrious-class ships had a flight deck protected by 3 inches (76 mm) of armour and the internal sides and ends of the hangars were 4.5 inches (114 mm) thick. The hangar deck itself was 2.5 inches (64 mm) thick and extended the full width of the ship to meet the top of the 4.5-inch waterline armour belt. The belt was closed by 2.5-inch transverse bulkheads fore and aft. The underwater defence system was a layered system of liquid- and air-filled compartments backed by a 1.5-inch (38 mm) splinter bulkhead. Wartime modifications While under repair in 1941, Illustrious's rear "round-down" was flattened to increase the usable length of the flight deck to 670 feet (204.2 m). This increased her aircraft complement to 41 aircraft by use of a permanent deck park. Her light AA armament was also augmented by the addition of 10 Oerlikon 20 mm autocannon in single mounts with a maximum range of 4,800 yards (4,400 m). In addition the two steel fire curtains in the hangar were replaced by asbestos ones. After her return to the UK later that year, her Type 79Z radar was replaced by a Type 281 system and a Type 285 gunnery radar was mounted on one of the main fire-control directors. The additional crewmen, maintenance personnel and facilities needed to support these aircraft, weapons and sensors increased her complement to 1,326. During her 1943 refits, the flight deck was modified to extend its usable length to 740 feet (225.6 m), and "outriggers" were probably added at this time. These were 'U'-shaped beams that extended from the side of the flight deck into which aircraft tailwheels were placed. The aircraft were pushed back until the main wheels were near the edge of the flight deck to allow more aircraft to be stored on the deck. Twin Oerlikon mounts replaced most of the single mounts. Other twin mounts were added so that by May she had a total of eighteen twin and two single mounts. The Type 281 radar was replaced by an upgraded Type 281M, and a single-antenna Type 79M was added. Type 282 gunnery radars were added for each of the "pom-pom" directors, and the rest of the main directors were fitted with Type 285 radars. A Type 272 target-indicator radar was mounted above her bridge. These changes increased her aircraft capacity to 57 and caused her crew to grow to 1,831. A year later, in preparation for her service against the Japanese in the Pacific, one starboard octuple "pom-pom" mount, directly abaft the island, was replaced by two 40 mm Bofors AA guns; which had a maximum range of 10,750 yards (9,830 m). Two more twin Oerlikon mounts were added, and her boilers were retubed. At this time her complement was 1,997 officers and enlisted men. By 1945, accumulated wear-and-tear as well as undiagnosed shock damage to Illustrious's machinery caused severe vibrations in her centre propeller shaft at high speeds. In an effort to cure the problem, the propeller was removed, and the shaft was locked in place in February; these radical measures succeeded in reducing, but not eliminating, the vibrations and reduced the ship's speed to about 24 knots (44 km/h; 28 mph).["