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>> Home > Tags > prop tube

prop tube
brass tube
brass prop
prop shaft
propshaft alignment
racing prop
prop tube
hanley by basilsdad Sub-Lieutenant   Posted: 8 days ago
[Score: 8/10] 28"/700g hanley Capable of 4mph Single Propellor (3 Blade 40mm) Direct Drive to a tape drive (3 Blade) Powered by Lead Acid (12v) 2Amp/h Batteries - Comments: scratch built stand off model of uss handley i believe cant find the plans i used to confirm the correct name, the hull is 3mm balsa for the sides covered with 1mm white card, the bottom is 5 mm balsa. scratch built propeller 3mm shaft and tube to match , scratch built propeller and rudder and fittings, the boat was painted with 4coats of enamelspray primer and 4 coats of light grey enamel with a black bottom.

Red Cat hydroplane by RNinMunich Fleet Admiral!   Posted: 8 days ago
Hi, thanks for the info👍 I'm new to BLs, but learning fast, and your experience confirms my growing suspicions that outrunners not only deliver more torque than inrunners (size for size) but that they are also more reliable and seldom need water cooling. Your new motor seems to be a larger diameter 58mm?, as opposed to 31mm for the old one, so I begin to wonder if the old ones were simply overloaded by a big prop causing them to draw more and more current and hence cook! 😡😭 Check out this test drive (Italian)of your new type motor!! cheers Doug 😎 PS Caption says that with more than 3/4 throttle the boat becomes unstable! Then it flips 🤔

Crash Tender Shaft Tube Poistion by RNinMunich Fleet Admiral!   Posted: 12 days ago
Hi Neil, the pics look good 👍 You have 11/16" from keel to shaft centre so your max prop diameter is 32mm. You might squeeze a 35 in if you flat off the keel to hull behind the shaft. The fillet is a triangular piece of ply (or hardwood if you have some scraps) fitted between the top of the tube and the hull bottom (keel plate in your case) and reaching from the end of the tube just in front of the prop to the hull exit point and completely filling (hence the name 😉) the whole gap. Min 6mm thickness would be good. Cheers Doug 😎

Crash Tender Shaft Tube Poistion by RNinMunich Fleet Admiral!   Posted: 12 days ago
Yes Paul, with the boat in your picture you are right. BUT it has two props so the tubes and shafts go through the thin hull and have no other protection or support. Like in my twin and multi screw destroyer and cruiser. Also they are supporting bearings for the shaft cos the tubes stop at the hull exits. Here, as Dave rightly pointed out, and I also showed in the pics of my Sea Scout; if the shaft tube is properly fitted in the keel it has all the support it needs and I've never seen internal damage from a 'knock' to a prop shaft!? The fillet from tube to keel does the rest and absorbs any 'knocks'. If you want belt and braces wrap a thin brass strip around the tube just before the prop and epoxy it to the sides of the fillet plate. Which by the way is above and not below the tube! and Neil; keep Paul well away from your models!! 😉 Cheers Doug 😎

Crash Tender Shaft Tube Poistion by neilmc Commander   Posted: 12 days ago
Standard Saturday Mrs Mac decided I had other things to do before being allowed out to play but I think I've got there, just need to check it's right before gluing up. OK so I lied that I wouldn't be asking more questions on this topic😁😁 The hole has been opened out enough to achieve 3/4" but the photo doesn't really show it. It took some time to achieve it as well more time than I thought, even used my dremel at one point😁. But pmdevlin's tip on using a disc was a great help. The position of the outer tube on the hull needs a slight adjustment but nothing major and still achievable as no glue. I did have a check fit of the motor and came across another issue as there was no way I could achieve alignment of the shaft and motor which was made easier by Doug's universal coupling idea😁. I went for removing the last remaining piece of the old motor mount (should have listened to Dave a year ago) which took about an hour as it was glued in good and proper.😤😤😤😤😤 There is some clearance on the hull from the prop so think I'll be going for a 30mm prop as suggested by Dave as to my surprise mine is 40mm diameter. Hopefully the arrangement is all good and I can use Dave's and Doug's tips on getting it secured. I still need to blank off the water pick up and fit the new rudder tube. Also I think the motor alignment will still be interesting as after removing the last bit of the old mount the motor was interfering with the bulkhead behind it so removed so it. Also will possibly need to take some out of the hull centre piece to achieve a perfect alignment. Hopefully tomorrow will go well as will also fitting the oiler as seen on Robbob's Build Blog.

Crash Tender Shaft Tube Poistion by neilmc Commander   Posted: 14 days ago
Hi To you all thank you for the continued advice it is making life so much easier and I do like it when the thinking is done by experts. Paul The disc idea is an absolute bonus and will be using it for sure as it takes away the need for continued measurements. Dave The water scoop is going as like you and Doug say I don't need it no working monitors for me, just a working boat would be good. I'll be using measurements given to achieve shaft positioning as at the moment I have a 2 blade prop which I think is 30mm diameter so disc to suit will be used. Doug I like KISS it's worked for me loads of times in the past but I can't help buying shining things 😁😁😁 The shim idea on the prop tube is a good one but may still go for a support even though not needed it shines 🤣🤣🤣🤣. But it may still go back to the filler piece as all depends on how difficult it is to fit the A frame support. I purchased one at 8mm for the tube and not 4mm for the shaft. I'm looking forward to the weekend to get started and even set an alarm for an early start which is unusual for me. Im off to HMS Alliance as I do volunteer guiding there otherwise Id be starting now. Will keep you all posted hopefully with good news and no more questions - well on this bit anyway 🤣🤣

Crash Tender Shaft Tube Poistion by Dave M Fleet Admiral!   Posted: 14 days ago
Neil Your model is the 34" Crash tender with one prop. Twin prop versions as per the real craft do need the support. On a single screw you can add a fillet of wood to fill the space and provide the support. Paul may well have used a 50mm prop on his model but my measurements were fo a 30mm 3 blade brass prop and that works perfectly. Using a disc cut to the size of the prop is a useful tip when fitting the prop tube For very fast models you will need a water scoop but for a novice this is an additional complication and I doubt if you will need one. Hope you are progressing with fitting the shaft Cheers Dave

Crash Tender Shaft Tube Poistion by Dave M Fleet Admiral!   Posted: 16 days ago
Hi neil Not what you require. This is a bearing and frame for a shaft that extends beyond the end of the propshaft. The original design for an IC motor had the shaft much further from the hull, hence this support was required. As I advised on your other post you do not need this support. Just fill the gap between the prop tube and the hull with a triangular sliver of wood to provide support. The shaft should be no more than 3/4" below the hull at the prop end. Dave

Crash Tender Shaft Tube Poistion by Dave M Fleet Admiral!   Posted: 16 days ago
Hi Neil That link for the seal is for a flexishaft drive. Totally different to a propshaft and proptube. Used by the fast racing fraternity. I am not sure it would work in your setup. Anyone used one with a solid propshaft? Dave

Crash Tender Shaft Tube Poistion by Dave M Fleet Admiral!   Posted: 17 days ago
Hi Neil Sorry was in a rush this morning so misnamed the water scoop hole as the skeg. As regards the skeg you don't need it. Just fit the propshaft and then fill below with a fillet of wood as used in the original Aerokit models and mine. An oiler is useful but your shaft doesn't have one and for a novice they can be difficult to fit. Like Doug I solder mine. I see my friend Steve at Model Boat Bits stocks easy fit oilers and they would be fine if they are the right size for your propshaft. If you do get one make sure you remove the propshaft before drilling the tube and get all the swarf out afterwards. Dave

Crash Tender Shaft Tube Poistion by RNinMunich Fleet Admiral!   Posted: 17 days ago
Agree 👍 The longer shaft is an advantage cos it provides more flexibility and 'wiggle room' inside the hull for the motor mounting. One thing puzzles me! "Skeg hole"? Do you mean the water scoop hole? I always understood that the skeg is the extension of the keel intended to protect the screw and rudder, and in many cases is a metal extension of the keel to support the bottom end of the rudder shaft! See attached examples of rudder skegs; Billing Fish Cutter (an inherited restoration project!), Southampton tug, U25. Neil; what you referred to as 'the skeg' is generally known as an 'A bracket' or 'Bearing bracket'. It's purpose is to support the final shaft bearing just before the prop. On full size ships the shaft tube does not extend all the way back to the prop. It stops at the hull exit and the 'A' bracket supports the final bearing at the end of the actual drive shaft. See final pic showing the stbd. outer shaft of my HMS Belfast cruiser. (About to be fitted with new brass Raboesch props!) If I were you I would not even try to bend the bracket again, and would not screw it onto the hull as it was. This is a double violation of the hull integrity and will eventually cause water to creep into the wood and start it rotting! I would cut off the right angles and solder the legs together to form a solid unit, making sure that it fits tightly around the shaft tube!! THEN; when the shaft tube is correctly fitted in the hull and everything is cured cut a slot to fit the bracket into the hull and epoxy it in. Fill and smooth on the outside as needed. Looks better and lasts longer 😉 Again, see the Belfast pic. Cheers Doug 😎 So ends the 17th epistle from admiral Doug😉 Hope it helps!

Crash Tender Shaft Tube Poistion by Dave M Fleet Admiral!   Posted: 18 days ago
Hi Neil I have just been and measured my 34" Fireboat. The shaft is 8" long. In situ it is 3/4" below the hull bottom and 3/4" above the hull inside. Inside the hull the shaft rests on the former aft of the original engine space The prop is a 30mm 3 blade brass. My rudder is 2" in from the hull stern. The shaft is 3 1/8" inches from the hull stern. My skeg below the hull is 1 1/4" deep as this was on the original hull I renovated. It finishes 3" from the hull stern. If you haven't already I suggest you remove the water scoop and fill the hole with dowel and filler. I agree with Doug, leave the rudder in place if the distances are similar to that I have given. Looking at your pic it would seem you will be able to raise the shaft and still have room. To do this you need to cut the shaft hole towards the stern so the shaft can be closer. Do make sure the shaft is in the centre and straight and not aligned to the off centre rudder. A small hole aft of the rudder on the centre line with a cocktail stick may help. The water pickup is about the right distance below the hull but needs removing. You do need to check inside the hull to see that there is sufficient height on the prop tube to allow for alignment with the motor and base. This is just a check, the motor can be fitted and aligned later. Looks like a nice claen hull Cheers Dave

Crash Tender Shaft Tube Poistion by RNinMunich Fleet Admiral!   Posted: 23 days ago
Hi Neil, yes, very similar. Could be regarded to as a first step before applying Eze-Kote to give it a harder, knock and almost everything else resistant surface. Hammerite then sticks to it like the proverbial to the blanket and you have a super clean 'engine compartment' dead easy to keep clean. 😊 80 quid for a brushless !!! Do you want it gold plated or what? My Propdrive 2830 cost less than 20 knicker from Hobbyking and was delivered almost before I ordered it! Just make sure it comes from the UK or EU (still!?🤔) warehouse and not USA or Global. otherwise you might get stuck for import tax 😡 For the motor mount / shaft alignment: no one said it was easy, but Nothing's Impossible', maybe that's why I drive Toyota!!😁 back end is determined by the diameter of the prop you want to fit, which in the case of brushless motor should be roughly the same diameter as the brushless (outrunner). In my case 28mm motor and 30mm prop. This defines how far you can lift the aft end of the shaft, leave at least 1cm between the prop tip and the hull! This reduces unwanted interaction between the vortex from the prop and the lamina flow along the hull, result; more forward thrust and better rudder effect. (Didn't spend 30 odd years talking to shipyards for nowt😉) If you have plan (or at least a sketch - take some measurements if you don't have one of these and make a sketch) of the keel and existing motor mount; project back from the newly determined exit point of the shaft. Check how far forward you need to go to be able to comfortably fit the motor mount with good alignment and purchase a shaft of appropriate length. Cut a wood block to fit around the keel as the basic mount and 'fiddle' with it until your motor and mounting (e.g. the Robbe / Romarin 400 mount) aligns with the shaft line. Alignment is checked by running the motor at a fixed low speed with an ammeter showing the current it draws. Shim the motor mount up / down, and shift slowly from side to side until the current reading is a minimum. Then glue and screw everything in place quick before anything moves! Takes almost longer to describe than to do😉 The coupling type shown in my photo is called a 'Steg' coupling here in Germany (don't know the English🤔) and available from Krick Modellbau, for various motor shaft / prop shaft diameters, here the link to their English page- Part number for the 3.17mm (1/8") to 4.0mm version I used is 63902. part number for the motor mount I used for my 28mm brushless is 42117. Advantages (to me at least!) they are not as long as the traditional UJ and Cardan types, they are resilient but don't flop about like the UJ types so are much easier to fit and align. Cos they are shorter you can use 'em for mountings in confined spaces. And they don't make no noise!! 😉 One final tip (may not be so useful on hard plywood built boats!). When I had this problem with my destroyer I sharpened the end of an 8mm alu tube (same as the shaft tube dia) and used it to bore back from the hull exit to the last bulkhead before the motor mounts. the bulkheads though were 1/4" balsa! Nice and soft man 😉 Hope this helps more than confuses, but it all worked for me! Cheers and happy fiddling, Doug 😎

Deans Seaplane tender by Dave M Fleet Admiral!   Posted: 24 days ago
Hi Just had a quick Google as I was not sure of the size. There was the very same item on our For Sale section 5 years ago: "Deans Marine 1/24th Scale British Power Boat Co. Seaplane Tender Includes JP Power 400 Motor, Deans (MTronics) ESC, 5Cell NiMh Battery." That being the case any small brushless 28XX size with a Kv of around 1000 and 30 amp esc and 30 -35 mm 3 blade brass prop should suffice. I have similar in my 34" Fireboat and use an 11.1v Lipo. If you are new to LiPo you do need a dedicated LiPo charger and be aware that unlike other battery technology they pack a very heavy punch. You must follow the charging regime to the letter and make sure you do not overdischarge when running the model. There are some rather frightening U-tube videos of what happens if you ignore the rules! That said I have been using LiPos for several years now without any major problem, but I am always aware of the risks and make sure I don't take any unnecessary risks Good luck Dave

Crash Tender Shaft Tube Poistion by Dave M Fleet Admiral!   Posted: 25 days ago
Hi Doug and Neil Fascinating details about full size props and distances. Our scaled models sail in water which is not scaled so I am not convinced the maths helps. There are many examples of Fireboats on this site and as has often been mentioned the original Aerokits were designed when IC engines were the fashion and as a result the prop shafts were at a very acute angle to accommodate the fitting of the engine. If you have an original kit model the easiest solution is to remove all the engine mounts and any oil soaked wood from the hull together with the prop shaft and tube. You can then buy a suitable motor and prop and work out the best alignment. Buy a prop shaft and tube to suit the distance and adjust the slot in the keel to allow fitment. I usually make the slot big enough to allow for alignment, you can repair any gaps later. I usually tack mine in place with small dabs of superglue to hold in place, not too much as you may need to reposition. Once all aligned you can fill the gaps as Doug says with balsa. I just use Plastic Padding car body filler, but either will work. Once all is set hard you can fettle to the keel / hull shape and make good inside the hull. Not sure which model size you have but am attaching pics of my 34" Crash tender which may help. Happy restoration Dave