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>> Home > Forum > Boat Specific Chit Chat! > Precedent Perkasa
Precedent Perkasa
(2588 views)
Author Message
cormorant
(Fleet Admiral!)





Forum Posts: 167
5th Sep 2016 15:08  
>> Permalink
mdlbt.com/23463

Many years ago I built a 49 inch wooden hulled Perkasa which I powered with a Merco 61. In those days suitable water was hard to find so I got rid of it and am now kicking myself for doing it.
I am in the market for another one but whilst I can find many wooden hulls I am really looking for GRP or plastic.
Any ideas chaps?

Steve

cormorant
(Fleet Admiral!)





Forum Posts: 167
18th Sep 2016 21:06  
>> Permalink
mdlbt.com/23559

Thanks to a member of this site I have now acquired a part built GRP hulled 49inch Perkasa, which will make an excellent winter project.
As you can see, my previous boat was i/c powered, but this time I am going electric.
Twin shafts have already been fitted but I would welcome any advice or thoughts on motors and props please?
Thank you.


Attached Files - Click To View Large

Peter501
(Sub-Lieutenant)





Forum Posts: 39
6th Oct 2016 15:46  
>> Permalink
mdlbt.com/23772

Hi
I believe President don't do the glass hull now due to a fire at the factory who produced them so now only have the wood hulls. I also have the 49" Perkasa (grp) hull you can see a picture in my profile, I run mine on a single prop with the following set up and it runs very stable and very fast although you need a big water to open up to full throttle..........

Leopard 4074 brushless motor
Tinergy 120A ESC
35 prop
2x 500 4S lipos wired in parallel....... gives about 50 mins fast sail time even longer at a more scale speed.
Mtroniks digisound sound module
Spectrum DX2e wheel type transmitter.

cormorant
(Fleet Admiral!)





Forum Posts: 167
6th Oct 2016 18:09  
>> Permalink
mdlbt.com/23774

Thanks for that. Mine is already fitted with twin shafts and a friend has suggested that I use two 900kv outrunners with 60amp esc's.
I notice that you are using an Mtronics sound system, I assume for the motor sounds. What sound do you use as I understand that these boats were fitted with gas turbine engines?

Peter501
(Sub-Lieutenant)





Forum Posts: 39
7th Oct 2016 15:15  
>> Permalink
mdlbt.com/23782

Can't find a gas turbine sound anywhere but I used the air start diesel (details below off there advert)better than nothing and quite impressive ( I think ).

MTronik Digisound Large Multi Cylinder Air Start Diesel
Ref: 4462
The digiSOUND5m is the new marine sound module from Mtroniks Ltd. It is the worlds first 100% waterproof, plug n play sound module designed to take the hassle out of giving your model a realistic sound! The sound module requires NO programming or set up, it comes with a realistic sound pre-installed leaving just the installation to complete before you can get under way! The unit comes complete with built in amplifier, wiring loom and even a 75.0mm diameter waterproof speaker!
You simply install the unit in your model and go! There is no complicated PC interface to deal with or complicated set up, you REALLY do just have to plug it in and go!!! Add this to the legendary Mtroniks waterproof construction and you really don't need to look any further!
Peter

cormorant
(Fleet Admiral!)





Forum Posts: 167
8th Oct 2016 09:08  
>> Permalink
mdlbt.com/23800

Peter
Had a look at the Mtroniks unit. Looks good but the price puts me off.
I have found this one, http://www.modelsounds.co.uk/index.html which does various gas turbine sounds.
Unfortunately the sample is voiced over warning not to download it so I can't really get a good preview. Have you come across this one before?
Steve

Peter501
(Sub-Lieutenant)





Forum Posts: 39
8th Oct 2016 10:50  
>> Permalink
mdlbt.com/23801

Hi Steve
Yes I did look at the Masterblaster but it appears to be an on/off devise the Mtronics sound is portional to the motor speed
I.E. From a tick over it increases as you throttle up or down to relate to the motor speed, it picks the motor speed up from a sensor that is joined into any two of the three motor wires and must say the installation is very simple with the pre made and plugged wiring harness.
Hope this helps Peter

Dave M
(Fleet Admiral!)





Forum Posts: 1427
8th Oct 2016 11:15  
>> Permalink
mdlbt.com/23803

Hi Steve
The model sounds units produce realistic sounds but are not that loud if you intend to use them on the water.
I agree the Action and Mtronic units are not cheap but do mimic the throttle setting.
Which ever sound system you use you will need a good 20watt amp and large 5" speaker mounted on a baffle to get realistic sound on the water.
My Trent uses the original Action sound unit with a Technobots 20w amp and 5" speaker mounted on a baffle midships. The sound is easily heard on the water and I had to fit a potentiometer to reduce the sound when I display the model.
One of our club members downloaded a gas turbine sound from the internet and used a simple solid state player in the model. Sounded very realistic. I will ask him for the link and let you know the details.
Dave


Live long and prosper

Dave
Haverlock
(Fleet Admiral!)





Forum Posts: 425
8th Oct 2016 12:00  
>> Permalink
mdlbt.com/23807

I don't know what sound you actually require BUT as an off the wall idea if you get a small ducted fan setup and mount that in your boat you will get a turbine sound that would be loud enough.

https://www.youtube.com/watch?v=9tAvqTb-cag


"that's not a bug its just an undocumented creature."

Sir Terence David John "Terry" Pratchett, OBE (28 April 1948 - 12 March 2015)
cormorant
(Fleet Admiral!)





Forum Posts: 167
8th Oct 2016 18:52  
>> Permalink
mdlbt.com/23813

Gentlemen
Thanks for your advice and thoughts.
Dave
I look forward to more info from your club member. I'm still waiting impatiently for the new year to make a start so am spending the time gathering a few things together.
Advice on the power unit inclines towards two 900kv outrunners with 60amp esc's.
Not got as far as props yet. What do you think?
Steve.

cormorant
(Fleet Admiral!)





Forum Posts: 167
16th Oct 2016 19:00  
>> Permalink
mdlbt.com/23916

Hi Dave
Have you managed to contact your club member re the gas turbine sound yet?

Steve

Dave M
(Fleet Admiral!)





Forum Posts: 1427
17th Oct 2016 10:33  
>> Permalink
mdlbt.com/23928

Hi Steve
Sorry, no. He has a holiday chalet in N Wales and is possibly there making the most of the weather before the site closes at the end of OCT. As soon as he is home I will ask
Dave


Live long and prosper

Dave
cormorant
(Fleet Admiral!)





Forum Posts: 167
17th Oct 2016 14:59  
>> Permalink
mdlbt.com/23931

Thanks Dave. No rush as I haven't started the installation yet, though I just need couplings and motor mounts.

Steve

Dave M
(Fleet Admiral!)





Forum Posts: 1427
17th Oct 2016 16:23  
>> Permalink
mdlbt.com/23934

Hi Steve
Spoke with my friend today and was advised he purchased a cheap MP3 player form ebay and serched on-line for Sound effects. Downloaded a sample clip and made it into a full length sound using Audacity (free) or similar. As it's a gas turbine you do not need to have rising and falling sound so it sounds OK. He also loaded some gunfire sounds just to add to the realism. Sorry he dosen't have the link but there are plenty I found on the web.
I do have some video with sound of his Al Muzzia and will load to U-tube and send you the link.
Dave


Live long and prosper

Dave
cormorant
(Fleet Admiral!)





Forum Posts: 167
18th Oct 2016 11:42  
>> Permalink
mdlbt.com/23964

Hi Dave

Thanks for the info, it's worth a try. I will let you know how I get on.
Steve

cormorant
(Fleet Admiral!)





Forum Posts: 167
27th Oct 2016 14:59  
>> Permalink
mdlbt.com/24082

Hi Dave
I am having trouble coupling the motors to the shafts, due to the shafts being threaded BA.
According to Cornwall Models rubber couplings are only threaded metric, so unless I re-thread or change the tubes I can't use them.
However, they have suggested I use Raboesch Needle Couplings as an alternative.
What do you think?
Steve


Dave M
(Fleet Admiral!)





Forum Posts: 1427
27th Oct 2016 18:51  
>> Permalink
mdlbt.com/24086

Hi Steve
I have looked at the Raboesch site and can't see any BA threads on any of their couplings. The pin type couplings are noisy and more suited to an IC powered model.
😀 I probably have some couplings for the Perkassa but what exactly are you wishing to use? Ie what kind of coupling? Can you post a pic of the coupling? Do you know the BA size of the propshaft?
I'm sure I can help you with a bit more info
Dave


Live long and prosper

Dave
cormorant
(Fleet Admiral!)





Forum Posts: 167
27th Oct 2016 21:47  
>> Permalink
mdlbt.com/24088

Dave
The coupling I have been advised to use is the rubber one, due to the speed of the motor. Ordinary universal couplings won't be strong enough.
When I got the boat, the original inserts (for universal joint couplings) were screwed on to the shafts, but neither the existing shafts or the inserts can be used with rubber couplings, as these are only threaded metric.
I seem to have three options:-
1. Replace the tubes and shafts which would mean cutting big holes in the hull.
2. Re-threading the shafts to metric to take an appropriate sized rubber coupling.
3. Use Raboesch needle couplings which you can see here - http://www.cornwallmodelboats.co.uk/acatalog/raboesch-coupli...
Malcolm, at Cornwall Models, initially suggested option 2 but then suggested option 3.
He did say that the needle couplings were suited to i/c, but said the coupling itself was enclosed and unlike universals, not prone to expanding and breaking.
Hope this makes more sense?
Steve



Attached Files - Click To View Large

Dave M
(Fleet Admiral!)





Forum Posts: 1427
28th Oct 2016 10:22  
>> Permalink
mdlbt.com/24089

Hi Steve
I see the needle file couplings are nylon so should be much better than the original metal variety. Both types of Fittings on the link say they are good up to 2.5cc ic engines so I assume the advice given relates to use with ic engines where the power is not as controllable as with electric power. I refer to the fact that ic engines are often started out of the water then launched at high revs resulting in considerable shock to the couplings. My own experience is that universal are ok with electrics even high powered brushless.
I believe I would go with option 3 assuming you can get the fitting with the correct thread.
Re threading the shaft is not that easy and a possible better option is to re-thread the coupling. You will need a lathe to do this accurately to avoid misalignment damaging your bearings.
Should the joint prove to be noisy I suggest putting a sleeve of Silicon tubing ( as used for ic engine exhaust coupling) over the joint to take up the tolerance in the ball and pin coupling.
Regarding replacing tubes I usually obtain a new tube and shaft of the correct dimensions remove the shaft and bearings from the new and old fitting and replace the new in the old shaft. Only works if the old tube is serviceable and straight but usually works fine. As I have a lathe I can make new bearings should the tubes be of different diameters, but often this is not a problem.
Good luck and please post how you resolved the issue.
Cheers
Dave


Live long and prosper

Dave
cormorant
(Fleet Admiral!)





Forum Posts: 167
28th Oct 2016 12:20  
>> Permalink
mdlbt.com/24092

Hi Dave
Chris, who you met when I collected the boat, suggested looking at replacing the bearings and shaft, but as it was non metric, I didn't think it would be as straightforward as you suggest. I'll store that info away in case the needle couplings don't work.
The couplings will be with me tomorrow, so I will let you know how it goes.
I have attached a pic of my previous boat, unfortunately I have none of the power train.
As you can see, it's pretty basic and all the fittings came with the kit except the gun barrel (machined metal) and torpedoes (broom handles).
Thanks once again for your help and advice.
Steve



Attached Files - Click To View Large

Dave M
(Fleet Admiral!)





Forum Posts: 1427
28th Oct 2016 16:34  
>> Permalink
mdlbt.com/24094

Hi Steve
Twas a nice looking example. I hope you can make as good a version this time.
Dave


Live long and prosper

Dave
cormorant
(Fleet Admiral!)





Forum Posts: 167
31st Oct 2016 21:14  
>> Permalink
mdlbt.com/24155

Hi Dave
Both motors in and running smoothly.
Once the rudders and servo installed she will be ready for hull only sea trials.
Any thoughts on what props to start with?
Steve




Attached Files - Click To View Large

Dave M
(Fleet Admiral!)





Forum Posts: 1427
1st Nov 2016 10:46  
>> Permalink
mdlbt.com/24156

Hi Steve
I would go for a left and right hand brass 3 blade prop of a similar diameter to the motors. A quick test with a wattmeter should indicate if all is working within its power rating. You can then move up or down a size to correct to the optimum on water performance. You may need to water cool if heat is a problem but tghis is easily added later.
Good luck with the tests - any chance of some video on the water
Dave


Live long and prosper

Dave
cormorant
(Fleet Admiral!)





Forum Posts: 167
1st Nov 2016 13:31  
>> Permalink
mdlbt.com/24159

Thanks for the advice Dave. I'm sure Chris will be on hand to do some video if I ask him nicely.
Not too sure about the mechanics of a 'quick test with a wattmeter'. Can you elaborate please?
Thanks
Steve

octman
(Captain)





Forum Posts: 99
1st Nov 2016 16:09  
>> Permalink
mdlbt.com/24161

Have no fear, I will help you when the time comes. This was all explained in recent posts about motor amps. Chris

cormorant
(Fleet Admiral!)





Forum Posts: 167
7th Nov 2016 16:55  
>> Permalink
mdlbt.com/24240

Hi Dave
Power train installed and working. I am currently using 55mm 3 bladed brass props supplied by Jotika (Propshop and Cornwall Models haven't bothered to reply to my telephone and emails).
Chris only managed a short video and I didn't push the speed due to an open hull and rough water, hence the stills.
Looking promising so far and I will keep in touch as the build progresses.
Steve


Attached Files - Click To View Large

Dave M
(Fleet Admiral!)





Forum Posts: 1427
7th Nov 2016 20:37  
>> Permalink
mdlbt.com/24245

Hi Steve
Looking good. Its does look very mean and when finished will look the part. You may have seen my P150 36" version when you collected the hull. I sailed it on Sunday in some rather rough water. Good job it was so cold so I didn't mind the short sailing time.
I look forward to seeing some video of your model in due course.
Dave


Live long and prosper

Dave