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>> Home > Tags > rotation

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BRAVE BORDERER by jbkiwi Chief Petty Officer   Posted: 20 hours ago
If you are using 2 ESCs/BEC/UBECs with 2 plugged into 1 receiver you should remove the red wire from one of the plugs and tape it back to the lead, as both plugged in will possibly supply too much voltage for the receiver (you are getting double the voltage from 2 different sources) and this can cause the ESC to stutter . You should have no problems with Brushless out-runner motors as with the correct match with the ESC they should be as smooth as brushed. I have dual 2000kv 28/45 in-runners (with water jackets) and twin ESCs and 2 sound units using 1 receiver in my 64ft ASR model with no problems regarding proportional control (fwd or rev). I had a 28mm O/R in a Maiami ASR and it would crawl along (but the high noise was ear wrecking so have changed it back to brushed for now. I do have a similar slight high pitched squeal at certain speeds on one motor and this may be caused by the particular motor not 'syncing'properly with the ESC (Chinese cheap ESCs and HobbyKing /made in china motors) but short of changing that motor and ESC I am just putting up with it for now. The high pitched sync noise is fairly common and sometimes not fixable, (a number of my larger planes do it and its audible from 100m away (also amplified by a hull,-nice sound box). It can depend on the way a particular motor is wound (no 2 are identical) or even magnet placement/timing, as the may be hand wound by 2 very nice Chinese ladies at different ends of a bench ( just read some of the Hobby King motor reviews ) You could try changing the frequency on the ESC if it has that option as a higher motor Kv sometimes requires a higher frequency. Also make sure your ESC is set to the correct battery cell count. If it has an auto setting that should usually work best for general applications unless you are running fancy motors. Regarding interference, make sure you keep your aerial as far as poss from the motors and ESCs (even on 2.4 - I put mine right up in the bow) and there should be no problems. I have had 2 twin engined boats (my MTB & ASR) 1 brushed and 1 brushless running side by side 10" apart using the same radio for both (same type of Rec in each boat) with no problems at all. The bow down is probably prop shaft angle (the shallower the better) but if you are using counter rotating props you could try swapping props (inward rotation to outward) and motor rotation to see if it makes a difference. Also with 2800Kv motors you should be using small props (around 28-30mm diam 3 blade) as these motors are made to rev) as on a 2s battery they will be turning at around 20,000 dry and perhaps 18,000 wet (depending on prop) and if you load them too much they will cook with no cooling (assuming they are around 28mm dia ?) Only other thought - silicone couplings will squeal real loud if they slip.

SLA Batteries! by reilly4 Admiral   Posted: 18 days ago
Hi Ed, I have MTroniks ESC's including a couple of PNP types. What I do is to start by moving the stick to reverse then back to the middle, (You can observe the direction of rotation). Then to the top and back to the middle. This works. The SLA batteries have nothing to do with the issue.

What is the optimum prop shaft angle? by RNinMunich Fleet Admiral!   Posted: 1 month ago
Mornin' Ron, If you put the motor where the batteries are now - where will the batteries go? They weigh far more than the motor so moving them forward will push the CoG even further forward😲 Re shaft angle; as flat as you can get it for the size of prop you want to use. This is to reduce the forward rotation moment of the thrust which tends to push the bow down. The further back you fit the motor the larger the angle will inevitably become due to the space needed for the motor and mount! BTW: Why two NiMh batteries? I would be tempted to change the set up to a brushless and a single LiPo. This will significantly reduce the total weight as well👍 You did say the boat is 'a heavy model'! 😉 Doug 😎

20th Scale ELCO 80ft PT boat part 6 by CB90 Fleet Admiral!   Posted: 1 month ago
Dry fitting pro-shafts (Note, all shafts parallel with the keel) Drilled with an old prop-shaft which I modified to a cutting tool then finished with a round file and cut slots for propeller-shaft support bracket with a hacksaw, file and knife. Note these shafts are lightweight aluminium tube with steel liners and steel shafts. props at currently 40mm but as with all things scale things are not always practical in scale size such as propellers and rudders and in this case the direction of rotation (not all going round clockwise).

ESC info... by RNinMunich Fleet Admiral!   Posted: 2 months ago
Or this one and it has Blocked rotation protection (senses a jammed motor and stops motor rotation) 👍 Get one of these to go with it so you can get the best out of the ESC and motor Ciao, Doug BTW: Some stuff might be out of stock at the UK warehouse but still available at the EU warehouse in Holland. You'll get the stuff just as quick from them and still duty free - until BREXIT 🤔

Sea Trials and mods. by robbob Fleet Admiral!   Posted: 2 months ago
It’s been a while since the boat had it’s maiden voyage on the lake at St. Albans and I’m pleased to report that it looks really good in the water and goes like stink if you open up the throttle. Sadly I still don’t have any decent video of the boat yet as I can’t film and drive the thing at the same time, but I do have some static wide shots from my GoPro. When I do the video I’ll ask a cameraman mate to do the honours, maybe I’ll put the GoPro on the bow and then the stern to get some low action shots…the storyboard is already building in my head!! These early runs were great as they showed up some minor problems that needed attending to. I found that it needed ballasting slightly as it was not sitting on the waterline evenly from side to side so I flattened out some old lead water pipe and cut it into small sections so that I could add ballast incrementally. I did this in the ‘domestic test tank’ and once I was happy the lead pieces were fixed in place inside the hull with some super strong double sided tape. The ESC needed a little programming adjustment because I had forgotten to set the low battery level point to ‘off’ as I am using NiMh batteries and not LiPo’s , that was the cause of the short initial run time on the first outing…..DOH !! The batteries are now held in place by Velcro straps on some bearers that I added, otherwise a battery change involved cutting cable ties and replacing them at the lakeside…not very practical. The volt/amp/watt meter is also now on a proper bracket so that the display is more readable. I have also changed the charging connection from the nasty Tamiya connector to a nice little panel mount XT 60 connector that HobbyKing sell, it comes with a handy blanking plug that I have drilled for a retaining cord. I have also finally got around to upgrading the firmware on my Turnigy i6 radio to the 10 channel version so that I can assign the lighting to the switches properly and have the rotation of the searchlight on one of the two rotary knobs. I can use the old 6 channel RX in the new boat….blog coming soon.

RE ads90's Vosper Firefloat by Westquay Fleet Admiral!   Posted: 2 months ago
The real boats, perhaps oddly, all used same direction rotation. Martin

Hull Pt2: Motorisation - Come What May!! by RNinMunich Fleet Admiral!   Posted: 2 months ago
As promised (or threatened?😁) stage two of the hull work and thoughts on motorisation. The hull was sprayed with two coats of grey primer/filler. Pic1. As usual this showed up the remaining imperfections (pics 2 & 3), but I'm not going to worry about them until I've got prop shaft tube and rudder stock sorted out and permanently fitted 😉 After my attempts to make and thread a 3mm prop shaft went awry Martin (Westway the Mechanicals Master👍) stepped in and made me a decent one complete with a bushed stuffing tube 👍 Vielen Dank Meister😊 I did however manage to make a 4mm to 3mm reducer so that I could fit a Rabeosch 35mm prop as seen in pics 2 & 3. The tube and shaft from Martin, arrived Saturday an' he only made it on Monday😊, have been dry fitted so that I can start setting up the gears, necessary to bring the drive down to the prop shaft fitted very low down in the hull, and motor mount. Pic 4. Motorisation: (Remember folks - this kit was designed and built as a static model!) I want to use the old 1950s Taycol Target motor which my Dad originally fitted in the Sea Scout which I have renovated and upgraded to brushless. See Build blog 'Sea Scout - Jessica' Many of you will know that the Taycol motors were field coil motors, meaning that they have no permanent magnet around the rotor coil, and thus reversing the battery connections to the brushes had no effect on the direction of rotation, as this simply reversed the magnetic fields of both stator and rotor coils🤔 To counteract this so that the motor could be used in both forward and reverse with a conventional brushed ESC I modified the motor slightly (separated the two coils) and built a simple converter board to connect it to the ESC. Again see the Sea Scout blog for the details of the conversion. Basically; once the field coil and brush-gear (rotor coil) have been separated a simple diode bridge can be used to apply the output of the ESC to the motor. This enables the reversal of EITHER field OR rotor coil polarity, depending on how you connect the converter to the motor. Thus reversing the direction of rotation of the motor. Beneficial side effect is that the diodes also suppress the commutator sparking😊 In my case, with the Taycol Target, I also cleaned, flattened and polished the commutator. Thus significantly reducing the potential for spark generation in the first place! A peculiarity of the Taycol motors is that they all use metal brushes, pressed phosphor bronze strip, so they need oiling! DO NOT oil conventional brushed motors with carbon brushes unless the brushes are exchangeable or you want to have to buy a new motor!!!!! Pics 5 & 6 show the proposed position of the Taycol in Gina 2 and pic 7 the prototype converter board I knocked up to test the motor, together with a Graupner Navy V30R Marine Brushed ESC. Details and results in the Sea Scout blog, including video of the sparks and oscilloscope pics of the drive waveforms before and after conversion! The latter showing the spark suppression effect of the converter😊 Some samples attached - last 3 pics. Pic 8 pic shows a more compact version of the converter, one of a few types I'm doing for Martin's various Taycols as a trade for the prop shaft he made for me and some useful material he sent. Thanks mate👍 Next steps will be 1) mounting the gears correctly on the shafts, requiring the manufacture of a 3/32" to 4mm adaptor and a 1/8" to 4mm adaptor, and keying them to the shafts - Hooray for mini milling machines 😉 2) manufacturing bushed end plates to hold the gears in place, 3) fitting the motor mounting platform. I'll probably borrow from my experiences of real shipbuilding and do this as a suspended 'false floor', i.e. mounted on stiff springs to enable adjustments to optimise the gearing mesh! On real naval ships this is done to improve shock resistance and to minimise engine noise / vibration conduction to the hull, thus significantly reducing the acoustic signature of the ship. Not that I'm tooo worried about being torpedoed 😁 Worth a try😉 Pic 9 shows the cleaned up and renovated Taycol Target motor. Pic 10 shows the drive waveform complete with sparks before modification.🤔 Pic 11 the cleaned 'forward' waveform with the converter board. Pic 12 the cleaned 'reverse' waveform, no suppression capacitors needed 😉 More soon folks, Cheers, Doug 😎 PS Along the way a new keel was fitted as can be seen in pics 1 to 3. The original builder had 'buried' the keel in the hull planking! 😲

Spektrum, new, useless... by RNinMunich Fleet Admiral!   Posted: 3 months ago
Hi Martin, First your last question😉 "What DO you do with a 3rd channel?" Example: 5 foot destroyer! 1 Throttle. 2 Rudder 3 Gun rotation, servo and pulleys 4 Torpedo tube rotation, servo and pulleys 5 Smoke switch, servo and microswitch (Smoke could be linked to the ESC to free this channel for the ASDIC pinger!) 6 Split into four functions (by misusing the gear down lever on my Graupner MC-10😉) for Whoop whoop, Fog horn, searchlights and signal lights, NAV lights. All switched via a home brew decoder / switch board and 5V relays! Alles klar? 😉 Re the DX5e; If I were you I'd let a (supposedly?) Spektum trained guy look at it first. With luck he'll have a service manual or at least a circuit diagram, which I don't 🤔 and should know the binding procedure backwards. I could only do some rudimentary tests without the circuit diagram, and make some educated guesses. I could at least try binding it with a variety of Rxs, including my Spektrun RXs which all work faultlessly with my DX6. Up to you, will PM my address anyway. I could at least check, with a simple RF meter, if the damn thing is transmitting at all! Just thought - if you're going to smash it anyway ........ 😉😁 Cheers, Doug 😎 PS: 4th attempt at the prop shaft for the cutter also failed 😡 She just does not want to get her bum wet!! Too long 'on the shelf' 🤔

CB90 by CB90 Fleet Admiral!   Posted: 5 months ago
CB90 Model boat, 52 inches long performing 360 degree rotation on its own axis. The Combat Boat 90 (CB90) is a class of fast military assault craft originally developed for the Swedish Navy by Dockstavarvet. Powered by two 9.6v Graupner 700 turbo motors (no-longer in production). Two Mtroniks Viper Marine 25 is a Brushed Speed Control designed specifically for use in RC model boats, it has a 25Amp motor limit and has proportional forwards and reverse functions

H.M.S. BRAVE BORDERER by RHBaker Fleet Admiral!   Posted: 5 months ago
An unexpected opportunity arose to try the unfinished hull in a small pool. Whilst the performance envelope could not be explored, was able to try and measure operating parameters and get a “feel” for the model. Used an electronic scale and a combination voltmeter/ammeter/wattmeter to measure propeller thrust /bollard pull and motor power requirements. If it is necessary to fit different drivetrain components, or a 3S cell this will serve as the baseline. The model floated levelly and well above the waterline. At about 8 volts the motors drew around 20 amps each at full speed; so only about 35% of the potential output capacity was being used. Tested each motor individually and measured the bollard pull at just over 2 lbs. A considerable amount of spray and wash was created making stable readings difficult. For further testing, will add ballast at the stern to hold the propellers further underwater. Should help reading stability. Currently using 20 A fuses; which as one failed seem marginal. For sustained use think 25 or 30 Amp better. With these high-speed, low torque motors establishing the “dry” propeller rotation is deceptive. Found one motor to be reversed! Nevertheless, the model accelerates quickly and is sensitive to engine speed movements. Left the pool with a list of modifications to make before assessing the installation properly on an adequate body of water. Some conclusions can be made though. If it is necessary to add a second cell this needs to be located around midships, not in the bow or stern. Still hoping a 3S cell will not be necessary and that 2S may be adequate. The suggestion to do testing using the bare hull with a minimum of detail was a good one. For a models with a sophisticated power train think this is a good approach. Nothing worse that finishing a boat just to find the performance disappointing, then have to to rip it apart to make major modifications or adjustments!

47" Fireboat power question by ronrees Sub-Lieutenant   Posted: 5 months ago
Hi Shaun, This design of hull forces the craft higher and higher the faster it goes. When it is high on the plane and almost hanging on the last few inches of propshaft it can fall off the plane either way, usually to the right (Starboard) side because of engine torque. The full size boats were fitted with 2 or 3 engines to help counteract this. The British Powerboat Company, who originally designed the hull that Vospers copied back in the 1930s/40s also noticed this which led to double skinning the hull with 1 inch thick mahogany for extra strength against pounding and falling on the waves. Lowering the drive angle of the propellor shafts and adding more weight from the C of G back to near the stern. We build this 3 screwed designed hull with one mainshaft usually so do not have the benefit of shaft rotation to stabilise the boat at speed. It was in the 1960's that Fairey engineers had the same problems (Swordsman,Huntsman etc) They came up with large transom mounted powered Trim Tabs. Their boats had similar problems and only one shaft in the main. I suggest you try fitting 2 x 2 inch wide by 1 inch deep trim tabs at the very bottom of your transom midway between the keel and the chine as well as move your battery packs forward a bit initially. Try some fast tests with this, you only need 2 to 4 degrees of down on the tabs initially. Add removeable weights near the CG as needed, a bit at a time but don't stop the bow lifting up onto the plane. Have fun, best of luck. Ron Rees

Cabin windows again by mturpin013 Fleet Admiral!   Posted: 5 months ago
Having remade all the front cabin window frames I then decided to fit the acrylics into the opening (nice tight fit) all done! Or maybe not, someone then said how about “opening windows” it’s been done before. So would opening windows be a problem with water ingress? And would putting foam seals solve this problem? I’m not convinced. Having given the problem some days thought, how about going with the windows as planned which are now 1.5mm thick and inset into the surround. Then fitting an over window frame 1.0mm ply/plasticard with another thinner (1.0mm) acrylic window and hinging this above each window. This would solve the issue of water ingress and also give the appearance of opening front windows. Looking at how one other person approached this, it looks like the hinge was a brass tube across the majority of the window top and then a shorter piece the same dia tube at each end with an internal wire for rotation these short pieces are then fitted to the body of the inner window frame. These additional window frames can be added at a later stage and this doesn’t hinder the final finishing of the roof skins. So final fitting and adjustment and then pin and clamp in position the forward roof skins. When these are dry the window frames can be finally trimmed and then pinned into position and checked for fit then removed and then to each one apply the aliphatic glue and fit –pin and clamp in position

HMS HOOD by Trumpeter by RNinMunich Fleet Admiral!   Posted: 5 months ago
Even tastier with the Frankfurters, and Colemans Mustard I trust😜😋 Steve: I found a cheap way to mechanise the two aft turrets of my H class destroyer Hotspur, using one servo with a pulley, a couple of smaller pulleys on the turrets, about 2:1 ratio to give at least 180° rotation at the turrets, and a spring loaded nylon cord around the pulleys. I'll see if I can dismantle her over the weekend to make some pics. I plan to try something similar with my 1:350 Hood, also Trumpeter and also excellent detailing. Another way is to use one micro servo per turret, connected with Y cables if you want a synchronised Broadside; A+B and X+Y turret. Then use the servo travel adjustment at the TX to maximise the rotation. You can then move all four on one channel or two channels for 'Independent Firing" fore and aft. I will use the two pots at the top of the Turnigy i6 TX for this. On Hotspur I used the left stick left/right. I plan to do this in my Graf Spee, Belfast, Hood and Bismarck. Maybe also the ack ack turrets on Ark Royal!? Will knock up some test jigs sometime 🤓 Cheers Doug 😎

Graupner ranzow refitting by kmbcsecretary Fleet Admiral!   Posted: 6 months ago
Here we have the working crane for lifting the buoy's into/out of the water. Again this was converted to working by using three micro motors rated at 300-1 plus one gear box at 5-1 to operate the rotation and a 4-1 gear box to operate the lift and lower first pic shows the crane completed second pic shows the line winch motor which is just a 300-1 micro motor. third pic shows the lift and lower arm with the motor and gear box is hidden in the crane body fourth pic shows the micro motor and gear box that controls the rotation, there is a similar layout that controls the lifting arm the final pic shows the micro speed controllers that you can do the fine control of setting the required speed that you want. Ron