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Author Topic: Prop for deep v??  (Read 12838 times)

Lt. Raen

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Re: Prop for deep v??
« Reply #25 on: May 06, 2010, 09:30:19 AM »

The engine is just sitting in there at the moment (not attatched to the bulkheads or anything)
rubber mounts will be mounted and the motor lowered when i have worked out where the prop shaft will allow the engine to sit
I am not entirely sure why it didnt meet up, however it should be fine
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Lt. Raen

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Re: Prop for deep v??
« Reply #26 on: May 10, 2010, 01:25:58 PM »

As for radios if you want 2.4 then id go with the futaba fasst system that hops from channel to channel not just between two.

Mart this seems to suggest that there asre more options than just 2.4ghz for a radio, what are the other options as i thought that 2.4 ghz was the only viable option????

Sorry for all the questions {:-{

Raen
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BJ

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Re: Prop for deep v??
« Reply #27 on: May 10, 2010, 02:24:40 PM »

Mart this seems to suggest that there asre more options than just 2.4ghz for a radio, what are the other options as i thought that 2.4 ghz was the only viable option????

Sorry for all the questions {:-{

Raen

See http://www.rc-airplane-world.com/rc-frequencies-australia.html
You have   
    * 29MHz FM primarily surface vehicles
    * 36MHz FM primarily aircraft
    * 40MHz FM also for general use

You need to read the article carefully
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martno1fan

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Re: Prop for deep v??
« Reply #28 on: May 10, 2010, 04:40:02 PM »

Not sure what frequencies are legal over there but cheapest safe radio to use would be an FM set,dont use am radios with spark ignition engines though.Also be sure you use a resistor plug on the engine,plug should have the letter r on it.Fm radios are what everyone used to use before 2.4 ghz came out and they work just fine,many still use them.
Mart
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Lt. Raen

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Re: Prop for deep v??
« Reply #29 on: May 12, 2010, 06:22:30 AM »

Ok whilst i am waiting on some parts i decided to have a think about how i could layout the running gear in the boat.
So far this is what i have got:


The main part im not sure about is the actul prop shaft tube and whether it should be mounted like shown or on more of an angle to reduce the flex after the tube

Any help greatly appreciated

Raen
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martno1fan

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Re: Prop for deep v??
« Reply #30 on: May 12, 2010, 07:57:47 AM »

Hi you will need to have the tube go much further towards the motor,withing 1-2" i usually dont have more than 1 1/2" if i can help it.This means you have to bend the tube to meet up at the motor,the angle you have and the bend your showing is perfect.To bend the tube install the flex into it and slowly bend it over your knee till it fits pefectly,then cut it to its final length leaving no more than 2"gap max,any more and the cable can whip and snap.Heres a few pics of one of my hulls i did for a customer last year it shows the angle of the motor and the bend of the tube and the length needed etc.
Mart
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Lt. Raen

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Re: Prop for deep v??
« Reply #31 on: May 12, 2010, 08:11:16 AM »

Ahh ok thanks for clearing that up Mart, suspected that would be the case but couldnt remember seeing a clear photo or diagram of this and wasnt too sure about the bend distorting the tube. But i guess by bending the tube with the flex inside and keeping the bends shallow it stops the tube distorting too much.

Anyway just waiting on my first ever eBay purchase, just hope it all comes as promised lol  :D
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martno1fan

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Re: Prop for deep v??
« Reply #32 on: May 12, 2010, 02:00:45 PM »

Another way to bend tubes is tape up one end and fill with sand or salt then tip a bit out say 1" and tape up the other end and bend slowly ,this stops it kinking or colapsing,ive never kinked a tube yet by using either method  ok2.Just be sure to use 5/16 internal  diam tube ,thin walled brass is what you want.k&s tubing works if you can get it long enough but either way its the thin walled stuff you want.
Mart
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Lt. Raen

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Re: Prop for deep v??
« Reply #33 on: May 25, 2010, 12:55:34 PM »

Whilst i have been waiting for some parts to arrive (should be here tomorrow  %%) i have been doing some research into radio gear,
I initially settled on a Futaba 6ex tx with R617FS Rx and a standard and high torque servo.
I just want to confirm that this would be a good choice before i sink money into it.
Or would a pistol grip style be better for this kind of boat or is pistol over joystick (is that the right term???) just a personal preference thing
(must admit i do prefer the joysticks though)

Sorry bout all the questions but i don't want to get this wrong   :-)

Thanks

Tim
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Bill D203

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Re: Prop for deep v??
« Reply #34 on: May 25, 2010, 04:34:13 PM »

Just my choice is the Futaba 2.4 Ghz stuff. I run off shore boats and have not had one prob since i got it. I found the sparky engine upset 40mhz radio and had loads of trouble which all changed when i went 2.4ghz.
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Lt. Raen

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Re: Prop for deep v??
« Reply #35 on: May 26, 2010, 06:16:29 AM »

Got home from uni to find these waiting for me  %%



The prop appears to ba an octura x470 which is surprising as it wasnt listed as a brand name product (maybe just a rip off i dunno)
All the gear appears to be of a high quality with only a few minor issues appearing, these are:
The prop nut has no grub nut (not a huge deal to me at the moment as the prop and dog nuts werent even listed as coming with the flex shaft  ok2)
The rudder is attatched to the 90 degree mounting bracket by two short screws but no locking nut which i might change as i would feel a little more comfortable if it had a lock nut n it (dont want the rudder falling off on me  %) )
Only the flex collet to arrive before i start to put it in the boat.
However still a lot of work to do to the hull between now and then,
I have to add a chime line and was thinking of using atuobody filler to build up a line then cover with epoxy resin when i resin the rest of the hull would this be a good way to make a chime line?

Cheers, Tim
(p.s. perhaps this thread might need a more appropriate name now that it has well and truly move on from just a prop choice  :-))
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w3bby

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Re: Prop for deep v??
« Reply #36 on: May 26, 2010, 09:48:51 AM »

Choice of stick or pistol radio is just personal preference. Most of the FSR-V guys I know use a stick whilst most of the offshore and hydro guys use a pistol, mainly down to the fact that the V boats need more channels. Choose that which you are most comfortable with. Personally use a Futaba 3PM 2,4GHz Fasst. One good thing is that it has an inbuilt failsafe, has to be set every time if you are using analogue servos but can be a real boat and lifesaver.

Hardware looks fine although the bullet propnuts aren't my favourite, I prefer a locknut. The bottom screw holding the rudder blade I would replace with a brass or nylon sheer bolt so the rudder will kick up without destroying the transom if you hit debris in the water.

Lt. Raen

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Re: Prop for deep v??
« Reply #37 on: May 28, 2010, 07:20:17 AM »

Got some work done fibreglassing the hull this morning
And started work on making up some chimes for it as well




During the week i made an engine mount as well
The engine is spaced by rubber mounts at all points its connected to the mount and there will also be rubber between the mount and the hull to help reduce the effects from any vibrations
And dont worry that exhaust is getting replaced  :-))
Just looking at ways of making a pipe for it



Still need to add more resin to the hull before i can achieve a smooth finish but i think i will add the chimes before working on getting the hull smooth

I will need a name and colour scheme before long  %)
im thinking black with red trim, no idea about a name yet though

Any help and comments appreciated

@w3bby good point about the bolt on the rudder went and got a brass bolt today to try to minimize damage in the event of a strike on the rudder. Yeah i think i prefer the sticks just never really enjoyed my mates pistol style radio, the 6ex also has an inbuilt failsafe and i found one at a good price so i will most likely get that

Cheers, Tim
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martno1fan

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Re: Prop for deep v??
« Reply #38 on: June 01, 2010, 11:27:57 PM »

6 ex is a good radio does your rx have the two small antennas or one?,mine has two and i even ran mine inside the radio box with no issues.Personally id have filled the keel and kept the glass for inside as it would save a lot of work sanding ,be sure to wear a mask when you do.You might want a slightly bigger prop something like a 275 or even a 280 prop or failing that go for a 3 blade with 70 or so mm diam.Are you going to add strakes under the bottom of the hull?,they really help create lift especially when your using a weedy engine that doesnt have much power.
Mart
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Lt. Raen

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Re: Prop for deep v??
« Reply #39 on: June 02, 2010, 04:44:17 AM »

Strakes?? what do u mean by this

I was talking to a friend who makes full size boats and he recommended adding a fin to the keel to help with turning

The keel is quite smooth at the moment, between the resin and the filler i have applied since these photos its turning out quite nicely.
although your right it has required a lot of sanding with the wet and dry (wet) to get to this stage.
A facemask is a very good idea, i have been wearing a facemask whenever i sand

I will be getting the 6ex with the 2 small antenna

I will be ordering one maybe 2 more props once funds allow so i will remember to up size  :}

Thanks for your help

Tim
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martno1fan

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Re: Prop for deep v??
« Reply #40 on: June 02, 2010, 07:58:01 AM »

Hi Tim i cant find pics of my old woodys bottom,must be some on my old thread?,anyway if you look on most fast vees they have strakes on the bottom to add lift.Most stop before the transom but on these woodys with a trimmer motor id advise running one  either side of the keel about half way between keel and chines and go from transom to arround half way or at least a third of the length of the hull they will help get the boat up on plane easier especially with a low power motor.
Mart
Heres a pic of one of my Apache Hulls showing strakes,these dont go to the transom but on yours i would but id just use one either side .
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martno1fan

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Re: Prop for deep v??
« Reply #41 on: June 02, 2010, 08:22:12 AM »

Managed to get some off my orriginal build thread on another site lol.I used pins to hold it while the epoxy set but you can pin it permenantly at the transom if your transom is thick enough  ok2.
Mart
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Lt. Raen

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Re: Prop for deep v??
« Reply #42 on: June 02, 2010, 08:27:44 AM »

Ahhh right thats making sense, just like on the full size things lol

hmmm i will have to work on that one, i dont think i will be able to use quite the same method as i did for the chimes but im sure something will present itself when i have a poke around bunnings  ;D

Tim
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Lt. Raen

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Re: Prop for deep v??
« Reply #43 on: June 02, 2010, 09:14:00 AM »

Just been having a think about the prop size
In full size ski boats if you increase the pitch of a prop on a given engine then you change the "punch out of the hole" and the top speed.
The punch out of the hole i refer to is i guess the take off of the boat from a standing start. this usually gets better with a smaller pitch then a large pitched propeller until some point where it becomes counter productive.
This reduction in pitch however tends to create a lower topend speed, actually a lower speed across the whole rev range
That is to say that:

at 2000 rpm with a 21" prop the boat may be going 35 mph
but with a 19" prop pitch the boat will only be going 30mph at the same rpm but the 21" may tend to "bog down"

So you have to have a tradeoff between punch out of the hole (torque?????) and top end speed
Does the same thing occur on the much smaller scale of the RC boats?
For example the 98mm pitch prop i have at the moment might give more punch our of the hole but less top speed so if i retain the same diameter of 70 mm or there abouts and just increase the pitch i would get a faster boat assuming that its the same as my personal experience with full sized boats.

I guess i can only really confirm or deny this theory by actually testing different sized props but I'm interested to know your views on pitch

also Whit effect does increasing prop diameter have?

Thanks once again  :-)

Tim (feeling like i should stop asking so many questions  :embarrassed: )
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martno1fan

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Re: Prop for deep v??
« Reply #44 on: June 02, 2010, 12:34:07 PM »

Your thinking along the right lines,reason im saying go with the prather 275 or the 280 is been larger and having more blade you can take better advantage of what weedy motors have which is reasonable torque,the 270 prop will need to spin much faster to get the same results which isnt possible with a weedy engine they just dont have the rpm so most go with the larger diam props.the two i mentioned ar probably about the best for most stock weedy engines.Save the smalelr diam ones for when you decide to geta  zenoah or similar  :-)).Be sure to ballance and sharpen the prop if you get a brass or stanless one,the ali ones dont usually need it.
Mart
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Lt. Raen

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Re: Prop for deep v??
« Reply #45 on: June 03, 2010, 08:27:53 AM »

Just been working on making the hull smooth in preparation for its final coat of resin, so much sanding here   :((

Martin i was just wondering how you secured the deck to the hull? i have been looking at mine and have thought of using some
aluminium brackets but was just wondering if you had a more "elegant" solution.
Also where did you put the fuel tank? i am getting another one from the one that originally came with the motor as it didn't fit
due to its strange shape. I wasthinking of mounting it in front of the motor (towards the bow slightly) I guess i want to keep
the weight as far back as possibly at this stage.
Your comments about prop sizes makes sense, If i do end up getting a stainless or brass prop how do i sharpen/balance them?

With the strakes should i bring them up to the point where i have put my chimes?

Well I'm going to get back to sanding thanks for all your help

Tim
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martno1fan

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Re: Prop for deep v??
« Reply #46 on: June 03, 2010, 10:02:28 AM »

Hi to join the deck what i did was added some spruce strips to the top edge of the sides and glue the top on taping it down as i went and left it till it set.The tank usually goes in front of the motor but try and get the hull ballanced with everything in the hull roughly where its going to be mounted that means hang the hardware on the back too sit the hull on a dowel and move things arround till she balances on it.Go for a balance point of arround 30-32% measured from the transom.Do this before mounting the motor and use the motor as your way to find the balance point,i sometimes half fill the tank with fuel that way as you use fuel you know the balance wont change too much.You can make the strakes the same as your chines in length but even 2/3rds would be enough.For sharpening and balancing checkout the vids in the link and be sure to wear a  mask,you will need a prop balancer too or save some work and buy a balanced prop.
Mart
http://www.youtube.com/watch?v=fVLdD9xAm0Q
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Lt. Raen

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Re: Prop for deep v??
« Reply #47 on: June 04, 2010, 11:25:16 AM »

With the weather here in sydney so attrocious of late i have been looking into a new carby to help with performance.
I have been looking for the wa-167 but it seems to be very hard (if not impossible in aus) to come by.
I was wondering if the wt-644 or wt-257 could be used and what is the advantages/disadvantages of each?

Thanks, Tim
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martno1fan

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Re: Prop for deep v??
« Reply #48 on: June 04, 2010, 12:11:37 PM »

Hi i think both of those would be too big a bore for your motor,the 167 is an 11 mm diam bore i think where as the others are 13 mm if memory serves.If you had to use either of those id go with the 644 with the choke,but if you go to any lawn mower shop you may find a carb with a 11 mm diam bore.Whats the bore on yours now about 8-9mm ?.
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Lt. Raen

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Re: Prop for deep v??
« Reply #49 on: June 04, 2010, 12:24:29 PM »

hmm yeah the specs say 12.7mm bore for the 257 and 644, i was thinking the 644 with the choke would be better (its also cheaper lol)
So an 11mm bore hmm
as for the one on there now i will check tomorrow, i know that the one on there has troubles idling
am hoping a pipe on the exhaust will help to reduce this issue

well i may as well start looking an 11mm bore carby thenTim, waiting for his workspace to dry out  :D
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