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>> Home > Tags > contra rotating

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contra rotating
Counter Rotating Props by Trillium Commander   Posted: 2 months ago
Inwards or outwards - should the props be turning to meet together above the shaft or below it? Also from Wikipedia "Contra-rotating is where parts of a mechanism rotate in opposite directions about a common axis, usually to minimise the effect of torque. Contra-rotating propellers should not be confused with counter-rotating propellers, a term which describes non-coaxial propellers on separate shafts; one turning clockwise and the other counter-clockwise." Torpedoes are a marine example of contra-rotating props. Roy

Counter Rotating Props by pmdevlin Fleet Admiral!   Posted: 3 months ago
with my 4 foot fireboat, I use contra rotating props, from propshop. I was advised by them to have them turning outwards, as viewed from the rear, there was an explanation, I've forgotten it, however, on the water, at speed, turning was difficult, the boat just wanted to roll. I swopped them over, so turning inwards, and the handling was cured in an instance. Its easy enough to try one way, then the other, see what is best for you, but remember to use some sort of none permanent thread lock or you might lose one of your props

Counter Rotating Props by Dave M Fleet Admiral!   Posted: 3 months ago
Actually for ships with props on separate prop shafts it's counter rotating. Contra refers to aircraft equipped with contra-rotating propellers with rotation about the same axis in opposite directions. Contra-rotating propellers should not be confused with counter-rotating propellers on separate shafts turning in opposite directions. I was intrigued by this discussion, possibly because it reminded me of my model flying days. What would we do without Wiki! Dave

Counter Rotating Props by 4clubs Fleet Admiral!   Posted: 3 months ago
CONTRA AND COUNTER rotating Props . Actually both are correct. Probably counter rotating is more correct for ships. We could argue for days!! Anyway they both go in different directions. One clock wise when the other is anticlockwise, but make sure they have left and right hand props, not the same type or you will be in trouble.

Counter Rotating Props by 4clubs Fleet Admiral!   Posted: 3 months ago
They are CONTRA not COUNTER rotating and on LIFEBOATS they turn inwards on other vessels they generally turn outwards when the vessel is in the forward direction.

U35 clockwork submarine by mactin Chief Petty Officer   Posted: 5 months ago
U35... Finally done! 2 Months this one took! 3 Ballast Tanks Clockwork Timer for the compressed air system clockwork motor for the coaxial contra rotating tandem props. Maximum time on the bottom 1 hour. clockwork tinplate submarines are great fun!

1/200 Yamato by Tinman0405 Apprentice   Posted: 5 months ago
Hi guys Im having a clear out of stuff ill never get around to and thought Id give club members a chance on this one. If not its off to ebay next week. Ive decided to let my Barn find 1/200 Nichimo Yamato go. Bought about a year ago and really all ive done is taken it apart. Its been stored in a shed before that for thirty years but i reckon its 95% there. £350. Collection only from Dorking in Surrey. Pictures here of before stripping down: http://www.crispyandtherocketman.com/blank http://www.crispyandtherocketman.com/blank?lightbox=dataItem... What you get: As you can see from the pictures when she came to me she had been stored in someone’s shed for the last thirty years. Virtually all there but infested with spiders and covered with an inch of grime. Scroll forward six months and all the parts that could be teased away have been and washed and in some cases primed. Hull stripped and primed. The original noisey contra rotating gearbox is included but prop connectors had perished. Suggest replace this gear box anyway. Damage to the bow. Ok I won’t lie I dropped a hammer on the damned thing. The ABS plastic foredeck shattered. Took the opportunity to replace the oversize tread plate with correct scale 1/200 tread plate. Damage repaired. Old deck retained so that the anchor fairings could be remade to replace on new deck. Other fittings all salvaged to be refitted on new deck. Rear hanger remade to include a full hanger. Rudder stem needs to be trimmed to allow for deeper hanger. Easy job. Aircraft. Three included all apart for rebuilding. Boats. All present I think. Main guns . Started work on crafting two line railings as wanted to use plastic for strength as this was going to be a pond runner. Easy job to finish. Brass etch doors added Rest of the bits. Are all contained in several pots for sifting through. I can honestly say there will be a few minor items missing but nothing major or that can be scratch built. Very few of the single AA machine guns made it to me, theres a few for templates or casting f you can do that. Superstructure. Complete as far as I can tell. The Big AA guns are all complete and present. Some barrels are dinged but all present. Those that can be removed for working on have been. Rest are stuck on solid. If your interested PM me and Ill take pictures of what she looks like now for you.

U35 clockwork submarine by mactin Chief Petty Officer   Posted: 7 months ago
Hi MBW,s Tinplate clockwork torpedo/submarine propulsion is twin coaxial contra rotating props totally scratch built handmade. Its about half way through the build at the moment just doing the clockwork ballast timer and compressed air system. Cant wait to chuck it in the oggin.

Victory Industries Vosper Fire Boat RC conversion part 8 by smiggy Sub-Lieutenant   Posted: 1 year ago
This is the props bit from the instructions, "I bought a pair of contra-rotating brass props from the Prop Shop taking their advice on the best size for the boat (their ref 0871/3 M2). The prop shafts are Graupner jobs with 96mm tubes, 114mm shafts with M2 threads. At around the same time I bought half a dozen cheap 6V motors, the Intention being to use one per shaft." Forget the cheap motors, I'm running 2 x 280's at the moment and a 9V pack of AAA batteries spread out around the area where the original battery tray was. Not ideal. It's either more power, brushless, and lighter batteries or major weight loss, re-building the deck and above in lighter material. I still intend to rebuild the old one I dissected to see exactly was inside. I haven't the 'oomph' to this at the moment but it will happen, honest. In fact this discussion has got the juices stirred..... 👍

Veron Huntsman 28 by Haverlock Admiral   Posted: 1 year ago
I can make a suggestion since you need a simple system Have a look at these systems http://www.cornwallmodelboats.co.uk/acatalog/Brushless_Motor... at only 28 inch the smaller of the 3 would be more than powerful enough. Remove the red receiver lead from one of the ESC so only one BEC is in use. and couple them together through a "y" lead. a 3cell LIPO would provide all the power you need chose a capacity to suit the available space. If your not used to LIPO batteries then PLEASE READ UP ON THEM FIRST they are not robust. You would also need a LIPO specific balanced charger. Even though the 2 ESC would be driven by the same control channel you can still have contra-rotating props you can reverse the direction of a brushless motor by just swapping over and 2 of the 3 motor leads.

Propeller for single shaft boat by jarvo Fleet Admiral!   Posted: 1 year ago
HI Dave When the model moves away say from a dock it does kick the stern out to the left, (neutons law) then as speed increases she sails straight, although there is some trim used, this is with my Amsterdam tug, 24v motor 90mm prop, 40" long weighing approx 40 pounds, my other tugs are twin screw contra rotating Hope this helps Mark

HMS Nelson by Gdaynorm Sub-Lieutenant   Posted: 2 years ago
HMS Nelson, scratchbuilt to 1/8" scale. Powered by two motors driving twin contrarotating shafts with three blade props. She sails on Lake Lisgar, Tillsonburg, Ontario. I decided on Nelson as she took part in Operation Pedestal, from which I made a 1/216" waterline model of SS Ohio, the ship that saved Malta. She took a little over 600 hours from solid chunk of basswood to launch. Probably info collection took as long!

72" 6S Brushless Power by Haverlock Admiral   Posted: 2 years ago
Have fun ~laughs~ make sure its water tight and this is not being silly. If you have never seen fast boats in action https://www.youtube.com/watch?v=DUKXbIOcg94 You need to be able to adjust thrust angles and will probably need trim tabs. Setting up a fast boat starts with science and ends being a "black art" figure on it flipping on a regular basis. Get a prop balancer and sharpen your props before balancing them. Flexy shafts seem to be the "must have" drive train. http://www.cornwallmodelboats.co.uk/acatalog/fe-hardware.htm... http://www.cornwallmodelboats.co.uk/acatalog/race-rudders.ht... Not the only supplier but gives you some ideas as to the kinds of hardware you need to be looking at. If your wedded to a twin setup then you need to consider contra-rotating props so you minimise torque effects. If you use BEC from your esc(s) CUT THE RED LEAD from one esc. else you WILL fry something. I hope your pockets are deep enough cos going fast is EXPENSIVE ( divorce may be a cheaper option) .

Left Hand props and shafts by Dave M Fleet Admiral!   Posted: 2 years ago
HI Les Haverlock has already answered your question relating to the thread and I agree particularly with his advice to use a locknut. The use of the correct thread is very important if you are running a very fast and powerful racing type of model where the forces acting on the prop are not small and are best used to keep the prop on the shaft, even with a locknut. The use of a locknut on a scale model where both forwards and reverse may be used frequently should help keep the prop in place. As regards two props it is beneficial to use contra rotating props as the model will be more balanced under way and will also respond correctly to the rudder in both directions, as already advised by jgs43. If you are modelling a true scale model of an original, say a lifeboat, then it will be important to replicate the full size arrangement on your model.

Twin Electric Set Up for Marx Chris Craft Constellation by Dave M Fleet Admiral!   Posted: 2 years ago
HI Biggles If I may just add to Mark's reply, yes you do need two ESCs. Brushless motors run much faster than brushed and the original props on your Chris Craft may be a tad on the large size. This may cause your motors and ESCs to overheat so you need to check this on the water after a short test run. If you have or can borrow a wattmeter this will help measure the amps used In the water. Brushless ESCs can be reversed via the transmitter but many do not. In a fast boat this may not be a problem but It Is something to consider. as Mark says you can set the direction by altering any two of the three leads so no problem with contra rotating props. I agree with the comment about Imported ESC ratings, and whilst some seem OK many fail and Its a long way and wait to get a replacement. There are several on line suppliers In the UK offering suitable motors and ESCs and In my opinion they compare favourably In price with overseas suppliers. Dave