Cookies used in this website are gluten free, wheat free and dairy free. By using this website you agree to our use of cookies. More Info
Guest
Login Below
Join Us On Social Media!
   
Get The Model Boats App!
Apple App Store
Android app on Google Play


Help Support This Website
£
or enter custom amount

(Non Contributor)

Help support this free
website and donate.



£285 a year is needed to keep the website and apps online. Please consider donating £5 or more to help towards these fees.
All donations are securely managed through PayPal. Amounts donated are not published online.

Many thanks for your kind support.

Model Boats Website Team


Donation History
October 2017: 7 people
September 2017: 15 people
August 2017: 10 people
July 2017: 16 people
June 2017: 8 people
May 2017: 8 people
April 2017: 23 people
March 2017: 9 people
February 2017: 4 people


Unique Visitors This Month

Website Members

Terms and Conditions
Privacy Policy
Advertising
Contact


Model Boats Website
Active Users (8)
Login or Register
To Remove This Ad
Login or Register
To Remove This Ad
>> Home > Forum > Boat Specific Chit Chat! > raf crash tender
raf crash tender
(786 views)
Author Message
georgeo5664
(Lieutenant)





Forum Posts: 56
4th Jan 2017 18:16  
>> Permalink
mdlbt.com/25038

I have been brought a 46" raf crash tender for Christmas but it has no motor i was hoping a mfa 850 torpedo would be bigger enough to get this boat on the plane any help would be more than appreciated
thank you
George


Attached Files - Click To View Large

onetenor
(Fleet Admiral!)





Forum Posts: 167
5th Jan 2017 06:27  
>> Permalink
mdlbt.com/25041

It should be fine but may need gearing down 😊

Haverlock
(Fleet Admiral!)





Forum Posts: 403
6th Jan 2017 09:10  
>> Permalink
mdlbt.com/25059

Consider going brushless mechanically the motors are simpler ( no brushes) and they are more efficient. If you take the plunge and use LIPO batteries you can have any amount of performance.

Not sure but I think an 800Kv outrunner would give you all the power you need and no gearbox needed.

The torpedo motor has a recommended rating of
Operating Voltage 12 volts.
Current approx. 5.28A at max efficiency.
RPM at 12.0v - 4289 at max efficiency.
Weight 595g (approx)
Shaft Diameter - 6.35mm

The 800Kv has a 28A rating at 12 V

so a wattmeter and a bit of fiddling you can match prop to motor and get some performance


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

Sir Terence David John "Terry" Pratchett, OBE (28 April 1948 - 12 March 2015)
georgeo5664
(Lieutenant)





Forum Posts: 56
6th Jan 2017 09:45  
>> Permalink
mdlbt.com/25060

Havelock thanks for the in depth reply much appreciated when every i hear lipo i get a bit worried of fire and explosion but I agree with what your saying could you help me out with what sort or charger and battery i would need to go into the world of brushless

Haverlock
(Fleet Admiral!)





Forum Posts: 403
6th Jan 2017 10:53  
>> Permalink
mdlbt.com/25061

within reason you are not limited to LiPo batteries. My reasons for pointing you in their direction are their ability to supply current for lower weights.

I am not expert in their usage having only playing with them for a short time BUT once you take the plunge they are like everything else use some common sense and they are fine.

Charging requires a LiPo charger

http://www.ebay.co.uk/itm/Dual-Power-iMAX-B6-AC-LCD-Screen-D...

That's the kind I use ( will charge nimh nicad and lead acid also) as to batteries some is good more is better ~laughs~
Its a case of run times at the current dumping your using I have some 5500Mah 3s ( nominal 12v ) lipo you can link batteries in parallel to get increased runtimes.

One important thing to remember is not to run a LiPo down to too low a voltage the limit us usually given as 3.3v per cell so a 3s will give you a 9.9 v low point. IN practice aim for a higher cut off voltage.

Depending on your radio setup ( I use frsky ) you may be able to have your battery voltages echoed to your transmitter.

The charger will charge to full and also charge to storage voltages LiPo batteries must not be stored at full charge.

Probably there is a lot more you need to know Dave M is way more expert than I.


Attached Files - Click To View Large


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

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





Forum Posts: 315
6th Jan 2017 21:23  
>> Permalink
mdlbt.com/25125

George,

is it single or twin screw, and what is your budget, motor, speed controller, transmitter, receiver, batteries?

Do youi want to go fast for say 20 mins, or plod for ages!

Then I can advise...!👍

Paul

georgeo5664
(Lieutenant)





Forum Posts: 56
6th Jan 2017 21:41  
>> Permalink
mdlbt.com/25128

Hi Paul
it is a single screw not to bothered about budget to be honest was going to use a electronics 15 amp speed controller and a planet 6 radio gear buts that's as far as I got i have ordered a mfa torpedo 850 motor for it but can change if it's not right I am sure I will use it in another project 😁 thanks for your help

Dave M
(Fleet Admiral!)





Forum Posts: 1356
6th Jan 2017 23:56  
>> Permalink
mdlbt.com/25134

Hi George
I have seen the earlier posts and can't add anything to the advice given. However if you are going to LiPo's please ask before you buy batteries or chargers.

If you are wanting to go into fast speed and cost really isn't a factor, then Paul will give you all the help and advice you need. His Crash Tender is both detailed and fast👍.

It won't be cheap but if speed is what you wan't then anything is possible.

Paul
Glad to see you are back with the model boats, may I see you at St Helens open day?

Cheers
Dave


Live long and prosper

Dave
pmdevlin
(Fleet Admiral!)





Forum Posts: 315
7th Jan 2017 20:08  
>> Permalink
mdlbt.com/25154

Hi Dave, good to hear from you (sorry to hijack thread). 4 footer came out two years ago, Huntsman once in 2016, Its over 3 years since the 3 footer got wet! Orca once in 2016. I did build the PCF which I really liked, but it went immediately as too many people messaged saying they wanted it, so it funded some RC plane gear, which I am really into now. I sold a load of bits and bobs at the Blackpool show a few months ago, didn't renew with St Helens in 2015, or 2016, and wont this year.

However.... Robs excellent blog has got me interested again, and Stephen kindly did a bespoke 3 d printing project on something rc related, info and pics to follow when its finished!

Back on track...

George, I'm going to advise only things I have done, or used, I'm not one to say do this, or that, but actually I have not done it myself. No doubt others will disagree, but this is my opinion only.
Best performance in terms of speed is brushless, and lipo. Forget fear of fire and explosions, this only happens with abuse, and they are the common use with rc planes, helicopters, cars, its only boats that are really stuck in the dark ages with technology that have this big fear of brushless systems and lipos! However, to get initially set up, they do take more understanding and initial cash outlay, as you need a specific charger for one, and you do need to understand what you are doing.
Brushless motors will unlease the power far more than brushed, and are usually lighter.

https://hobbyking.com/en_us/turnigy-t600-brushless-outrunner...

This motor is an example, there are much cheaper ones with similar specs, but I have used this motor in various applications, the most similar to your boat being my large Huntsman, with this motor on 6 cells lipo I achieved 25mph, but speed might not be what you want. So if you have the fast engine in your car, say a v12 Ferrari, if you run it on cheap fuel, it wont perform, same here, nicads and nimhs batteries are easy to maintain, you can drain them dead flat, but will give cheap fuel performance, like a bath tap trickling when the shower is on at the same time, and as they are dying technology, are expensive for what they are. Lipo is like turning up both bath taps and the force floods out, but now the tank will empty quicker, so you have less run time 😊
If brushless, its a specific speed controller,

https://hobbyking.com/en_us/hobbyking-50a-boat-esc-4a-ubec.h...

and you pay extra for reversing (other rc disciplines don't need reverse) and a marine esc might need to be water cooled, however, decent brushed motor speed controllers are not exactly cheap, so now you know why budget is important to give advice, you could be spending £100 here just to get up and running.

Look at my 4 foot fireboat build blog, as its twin screw (personally a boat this size is better twin screw) you can get by with cheaper motors, mine where £30 the pair, I use lipo for all my boats, so I have the batteries, and are familiar with using them, the speed controllers where about £40 the pair, and if I was buying batts then probably another £40, so it all adds up!

Single screw, less batteries. You could power with nimhs, and it might be acceptable ,performance for you.

If your location is Ellesmere Port, have a Sunday morning drive to Hoylake, then New Brighton, and maybe take in St Helens Liverpool, and Runcorn, see boats in action, see what sort of performance suits you, and rethink the budget, what do you want to spend? Then you need the transmitter and receiver (if you don't already have these) the fittings (see Robs build blog) a prop shaft, and a suitable propeller

I am North Wirral, you are more than welcome to come and have a chat and see some boats, but unfortunately I'm deep into another rc project for the next few weeks, once that is done I can share some time, if you want! Don't worry, I'm not all about speed, I can do brushed motors and nimhs and get a result,

Any questions, just ask, Paul

PS... Looks like a nice clean boat you have there😉

georgeo5664
(Lieutenant)





Forum Posts: 56
7th Jan 2017 20:41  
>> Permalink
mdlbt.com/25156

Paul.

Thanks for all the info and thanks for the offer of help i will kindly take you up on it if you don't mind could you pm me when you are available and I will call up and see you sorry to be a pain but I really want to get this boat right as there is something about crash tenders that I really like.
Again I really don't know where we would be without the knowledge of the fellow boaters and this site 👍

pmdevlin
(Fleet Admiral!)





Forum Posts: 315
8th Jan 2017 18:42  
>> Permalink
mdlbt.com/25193

no probs George, pm your email address please its easier

Paul