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Author Topic: Severn trip tab mounts and actuator mounts  (Read 26357 times)

lesfac

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Re: Severn trip tab mounts and actuator mounts
« Reply #75 on: June 19, 2016, 05:03:21 am »

Well having gotten the running gear installed I just had to try it out so I took it to the Keepers Pond in Blaenavon and ran it. The video below is the second run as on the first run one prop shaft tightened up and the fuse to the one motor blew. It did prove that my home made couplings can handle some duress. I fixed that and the second run video's below was very pleasing.
The boat is running under scale weight and the trim tabs are not fitted but I am happy with how it went with one slight reservation that I would appreciate any suggestions on.
The one area I am not totally happy with is that the minimum speed of the motors is a bit high and they start with a bump making it not possible to troll along very gently. The motors are Emax BL4030'S and the escs are Hobbyking 90 amp. Batteries are two 5 cell lipos in parallel.
I also notice that the upper third of the throttle stick movement does not increase the motor speed. That's not a problem in terms of top speed as it looks fast enough to me.
I have tried a few different settings on the esc to try to do something about minimum speed but I haven't found a solution yet. I wonder if a transmitter adjustment might improve it.

Overall I am pleased with the performance and I particularly noticed the lack of roll when turning at speed
Video link below

https://youtu.be/eAEraL-Thw0

Les
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Canterbury Coxswain

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Re: Severn trip tab mounts and actuator mounts
« Reply #76 on: June 19, 2016, 11:10:22 am »

Hi Les,
That seems a very good turn of speed, even if over scale at top end, at least it is there if you want to use it - better than being laboured and too slow. Well done getting on that fabulous stretch of water - looks superb.
To the nub of your question I would start with the programmer for your speed controllers [ESCs], on the all the different ones I have you can programme them for 'soft start'. If you can, try that first. I am sure others will give advice on this regarding the Tx adjustments and gearing, but this is where I would start.
Great to see and thanks for the video post - keep up the good work.
Kim
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Re: Severn trip tab mounts and actuator mounts
« Reply #77 on: June 21, 2016, 09:02:52 pm »

Hi Les as Kim has said you will need to program the esc to a lower start up RPM, just looked up the spec


Specs:Constant Current: 90A
Burst Current: 120ABattery: 2-6S Lipoly
BEC: 5.5v / 4AMotor Type: Sensorless BrushlessCooling: WatercooledSize: 87 x 38 x 22mm
Weight: 105g
Programming Functions:Running Mode: Forward with brake / Forward and reverse with brake / Forward and reverseAcceleration: 6% / 9% / 12%Low Voltage Protection: None / 2.6V / 2.8V / 3.0V / 3.2V / 3.4VStart Mode (Punch): Level 1 / Level 2 / Level 3 / Level 4 / Level 5 / Level 6 / Level 7 / Level 8 / Level 9Reverse Force: 25% / 50% / 75% / 100%Timing: 0° / 5° / 10° / 15° / 20° / 25° / 30° / Autom
you have a start mode of 1 -9 so would try and set it on 1, do you have the program card for the esc, if not I would advise it this would make it much easier to set them up.
I also not that they are fitted with  BEC, remember to remove one red wire from one of the ESC receivers plug, so as only one esc is supplying the power to your receiver, but do it after you have set it up.
Next time you do a test run add some ballast she should weigh around 22 to 25KG wet weight thats in the water when shes finished.

Phil.

[/size]
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lesfac

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Re: Severn trip tab mounts and actuator mounts
« Reply #78 on: June 22, 2016, 11:24:45 am »

Hi Phil
Yes I have the programming card
I have just made some adjustments and it might be running a bit slower at startup but its difficult to tell off the water.
I did weigh the boat as I ran it in the video and its only weighing about 11 kg. So I am thinking about how to load and distribute another 12kg or so.
Taking it for the test sail made me realise what a big model it is and I think that any ballast of that weight will need to be "slot in" so that I can add it when the boat is in the water. Not as young as I used to be  :-)
Although the ESC's are 90 amp I only have a 30 amp automotive fuse on the feed to each esc. This worked fine with lots of full throttle running but on the first trial when a prop shaft tightened up the fuse did blow which is what you would want. So I will continue with 30 amp fuses. I Guess extra weight might cause more current but I will see how it goes.
 the settings i have put in now are mostly the low settings
1  Running Mode Forward & Reverse
2  Fixed Area Acellerator (????) 6%
3  Battery Low Voltage Protection 3.2V (I use other means aswell)
4  Start Mode (Punch) Level 1
5  Reverse Force 50%
6  Timing Set 0 Deg.

Theres lots more to get on with but I will give it another try out at some point.
Les
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Charlie

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Re: Severn trip tab mounts and actuator mounts
« Reply #79 on: June 22, 2016, 05:11:45 pm »

Hi Les, as CC has already said - what a beautiful location for boating. And the Severn does look big on the water, very nice.


Charlie

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Re: Severn trip tab mounts and actuator mounts
« Reply #80 on: June 22, 2016, 05:13:58 pm »

Thats a good starting point, will be interested to see who it goes. Its good to have a fuse lower than the esc full amps as it saves you blowing it up.


with regards to the weight you will not need to add to much when shes fully built, its surprising who much is added in the build.
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lesfac

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Re: Severn trip tab mounts and actuator mounts
« Reply #81 on: July 19, 2016, 10:01:13 am »

I thought this might be of interest to those who might own a lathe.
I have made my own prop shaft coupling and fitted it to my perkasa model. I have used it a fair bit and it is proving to be satisfactory.
The picture below shows the configuration. I did initialy use silicon rubber but that proved to be too soft so I bought some 12mm Nitrile rubber with a Shaw hardness of 70 and that has proved to be up to the job.
I have tried the Severn out with these couplings and they worked fine. The only problem with them was that they rust as you can see in the picture. I didnt have any stainless steel to remake them but I did have some aluminium so I have made the new ones using this.
The details are
Overall coupling length 70mm
Metal bits 30mm long
12mm diameter Nitrile rubber, Shaw hardness 70, 40mm long. 15 mm inside each metal bit so 10 mm showing in the middle.
Metal and rubber cross drilled 3mm 7.5mm from the inner ends of the metal pieces.
3 mm pins through the cross drilling. (I have used brass in the aluminium)
As you can see I have used grub screws to lock the motor shaft and prop shaft.
M5 for the 8mm motor shaft and M4 for the 4mm prop shaft.
I drilled the metal with a 15/32 (11.9mm) drill to take the rubber and took the sharp edge off the hole.
Obviously if you have the tools to make these you can customise the size to whatever you want.
This proves to be quite a strong coupling
Les

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Re: Severn trip tab mounts and actuator mounts
« Reply #82 on: July 19, 2016, 03:41:53 pm »

Les,
A nice bit of information and detail and I can see that with your photos this will lead quite a few modellers to make their own now - thanks for the effort and sharing this with us. They do look neat and purposeful.
Did you glue or fix the brass cross pins, or did the nitrile rubber 'grab' them sufficiently? Also, who were the suppliers of the rubber and what was the cost and, lastly, was there a minimum length you had to purchase?
Thanks,
Kim
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lesfac

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Re: Severn trip tab mounts and actuator mounts
« Reply #83 on: July 19, 2016, 05:25:09 pm »

Kim
I just refound the rubber on Ebay and it is "Metric nitrile o ring cord" . It is £5.39 for a meter of 12mm diameter. It has a Shore hardness of 70.
The nitrile does grab the pins and it takes some firm tapping to drive the pins through. I take the edge off the pin so it doesnt cut its way through the nitrile. However I think it's a good plan to put a very slight countersink on the 3mm holes then cut the 3mm pins just a couple of mm longer than the diameter of the metal they pass through. When the pins are through rivet the ends into the countersink and then skim the od in the lathe for a nice smooth finish.
On my aluminium ones in the photo the aluminium is anodised so I didn't skim it I just went as close as I dared on the pin ends.
I initially fiddled about with gluing but I was using silicone rubber at the time and it didn't glue so I pinned it and found pinning worked well so I don't glue now. I just try and ensure the rubber is a nice tight fit into the metal before cross drilling the assembly.
Just for info. On my first attempt I used smaller diameter silicone rubber and I think the Shore hardness was 60. This worked OK in my Perkasa until I tested it by holding the boat stationary and gave it full throttle. This did break the rubber out of the housing. That's why I went to larger diameter (12mm) and harder rubber and I have to say it feels much stronger
Les
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nemesis

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Re: Severn trip tab mounts and actuator mounts
« Reply #84 on: July 19, 2016, 06:18:28 pm »

Hi, Good couplings, made them for over 40 years except I use allen screws as well for securing the rubber, also keep the space between the halves down to the minimum, ie 1/8 or 1/16. Nemesis
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Canterbury Coxswain

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Re: Severn trip tab mounts and actuator mounts
« Reply #85 on: July 19, 2016, 10:10:26 pm »

Les and Nem,
Many thanks for this, always on the learn, even after 69 years [a youngster to some], but I think this will help quite a few others and get some of them building their own too. That's what is so good about this Forum when used informatively.
Cheers,
Kim
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Chris57

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Re: Severn trip tab mounts and actuator mounts
« Reply #86 on: July 19, 2016, 10:35:32 pm »

Hi, for mere mortals who don't poses a lathe......I have successfully used the brass inserts from a conventional (hucko ? ) coupling but substituted nitrile fuel pipe for the red connector bit. ( eBay, couple of quid for a meter)
Runs just as well, the splines on the brass inserts grip into the nitrile very tightly, any slight misalignment is carried by the flexibility of the pipe, and best of all, it is a lot quieter than the conventional coupling.


Chris
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Re: Severn trip tab mounts and actuator mounts
« Reply #87 on: July 19, 2016, 11:16:17 pm »

See what you have started Les! And another good idea comes in, I'll give that a try too on one of my many lifeboat couplings, thanks Chris.
Wife bought my small mini-lathe for my sixtieth birthday, some years ago now, never used one before, got a few lessons from an engineer on a 'one to one' basis in my own workshop and would not look back. Worth the small investment - just drop some hints around to various members of the family, I think it was my son-in-law that made the suggestion [stout fellow!]. I then bought a mini-milling machine and after 3 months my wife saw it in the workshop - 'what is that?' she said, 'the other half of your birthday present' came my reply, 'you only gave me the tool that deals with round metal, I also needed the one that deals with flat metal too!' That's the bravest I've ever been!!
Kim
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Chris57

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Re: Severn trip tab mounts and actuator mounts
« Reply #88 on: July 20, 2016, 12:38:43 am »

The proper reply ( wife's reply) is : oh this old thing , I've had it in the back of the cupboard for years' ......... :-))
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