Weston UK Capiche 50cc Revisited

[Peter Jenkins]

Interesting to read the prop size Adrian.  Do you know what sort of power/current that pulls in your other installations?  I was expecting a higher pitch.  I'm running a 23x20 front and rear on my 2 outrunners in my Anthem with the motors rated at 3,600 W and 99 A with a kv of 165.  In the air the telemetry rarely shows more than 3,000 W and around 80 A.

[Adrian Smith 1]

Hi, Peter. The recommended sizes for this motor are 22x10 23x8 23x10 24x8 24x9 24x10 and 25x10. 

On my Sbach 342  and Corvus which are both running on this motor I have used 24x8 props that from memory pull around 90-100amps on the ground at WOT. The OPTO ESCs used in these planes are Dualsky 140A-160A rated with bursts above that figure. Although I have been no where near that testing on the ground I don't have any telemetry so I don't know what occurs in the air. Working on this basis the fact I have not had any burnouts or failure issues over the years I have just carried on with this set up. I certainly agree that a larger pitch prop would be worth a try.  

 

My 91" Slick which also Goldwing is on the GA8000 series by Dualsky  and although this is meant to be a 60cc plane its size and weight made me use that motor which is designed for 80-120 cc conversions. That is running on a 26x10 but I have no info as yet on current draw. The OPTO ESC on this one is 160A-200A made by HobbyWing. Seems to be ok, but I should check it. Any observations will of course be welcome. 

[toto]

Fantastic thread and very neat work. Great to watch.

 

Thanks for posting.

 

Toto

[Peter Jenkins]

Hi Adrian,

 

I use a 3rd party telemetry device that will talk to most RC brands.  It's called a UnisensE and is made by SM Modelbau in Germany.  They make 2 versions - 1 rated to 140 A (Euro 65.90) and one to 280 A (Euro 86.90).  The difference seems to be just the size of wiring with which it is supplied.  You can specify what type of connector or just bare wires.  It just plugs between the pack and ESC and you plug into the Rx telemetry port.  There is also a useful MAX/ACTUAL/MIN feature that allows you to look at MAX values and that needs another channel.  There is also a lead to connect to one of the 3 phase wires to the motor that gives RPM.  (Link)  A customer of SM Modelbau has translated the manual into English but with the proviso that it is not guaranteed to be 100% accurate!  I have to say that it's served me well enough.  (Link)  The device is very small and weighs between 15 - 20 g so really in your aircraft you can ignore that additional weight.  

 

This gives you a read out onto your Tx screen of a wide range of parameters:  A, V, W, RPM, height, rate of climb etc.  If your Tx supports it, you can also set pack capacity in the Tx and this will decrement based on the UnisensE current flow x time.

 

One thing to note is that as soon as you switch off the Rx the information is lost!  If you want to keep all the information then they sell the UniLog which has a micro SD card to record all the data.  That is a bit more expensive at Euro 99.  I have never used this system but I might be tempted to do so in the future.  The English manual is here.

 

Make sure you buy the USB cable with the item as that allows you to:  firstly, set it up and, secondly, to take firmware updates.

 

It really is very simple to set up and is an absolute boon when it comes to checking out the current draw for your installation.  Obviously it can be used on the ground dispensing with external Wattmeters.  

 

In my opinion, they are worth their weight in gold as you can be sure of what is happening when the aircraft is airborne.  I found that the airborne current/power can be reduced by up to 25% compared with figures derived when the aircraft is tied to the ground as the load on the prop then becomes much more than when the aircraft is free to fly and that means for electric motors that they just keep demanding more current till the white smoke appears!

 

[Adrian Smith 1]

Cheers, Toto. Glad you find it of interest 👍

[Adrian Smith 1]

Thanks for your input, Peter. Sounds a great idea and worth me researching. I am not the most technically minded and I just sort of find what works and stick to it, but with these giant scale aircraft a bit more precision is required. 

[Ron Gray]

I too use the UnisensE devices linked to my FrSky system and can vouch for how good they are. Fortunately all the readings are stored in the log files on the Tx so can be browsed after the flights.

[Adrian Smith 1]

Good to know, Ron.

Might have to put it on my "to get" list. 👍

[Adrian Smith 1]

Right, on to the aileron push rod fitting. I found some alloy servo arms around 1.1 inch seemed fit the bill from Amazon. Geometry seems fine.

 

Simple enough job to fit the horns in a similar way to the elevators and rudder.

 

 

 

 

 

 

[Adrian Smith 1]

The one step I have omitted is the plastic tube insert to stop wood compression in the drilled hole. The tube requires a 7mm drill and makes a bit of a mess in the aileron so the horn holes only needs to be 4mm to accommodate the studding with the hole toughed up using a thin cyano dripped into the hole.

 

 

 

 

Much tidier. 

[Adrian Smith 1]

Next onto the motor end and fitting.

I taped the template on the motor wall and drilled out 5 mm holes.

 

 

Helpfully the stand offs and spacers supplied with the motor will provided me with the 70 mm stand off length from the motor wall to prop driver.

The stand offs are 65mm while the spacers totalled 5 mm.

 

 

 

[Adrian Smith 1]

Now to test fit the motor. I used my magnetic "radio aerial" to offer up the 5mm bolts as the motor box is by necessity well engineered. 

 

Standoffs added plus spacers.

with the motor temporarily bolted on.

Edited July 27, 2023 by Adrian Smith 1

[Adrian Smith 1]

Now to test fit the cowl. All looking good with the prop driver around of the cowl by 2-3 mm and centred through the cowl opening.

 

 

 

 

 

Clearly all this will be dismantled as I have to solder the connectors to the motor and ESC. Washer added to all bolts and blue thread lock to finished.

I must admit this part has gone well.

 

[Peter Jenkins]

Great work Adrian.  Getting the motor mount in the correct place is a real PITA.

[Adrian Smith 1]

Cheers, Peter.  Very true indeed although it helps that the side thrust is built into the motor wall ( I don't think there is any down thrust) and the position scribed into the wood.  I will measure how much side thrust is built in the next time I go to work shop and post here. 

[Adrian Smith 1]

Just had time to lay out the electrics to make sure I have everything I need for the motor power. Starting with the front end.

 

Connectors to the motor from the ESC.

 

 

Down the power train. AS150 anti spark connectors, 8AWG wires black and red, EC5 connector into the series connectors to the two 6S lipos.

All there, just need to allocate some time to have a major soldering session. The red side anti spark connector is essentially the on/off switch for the power train. The black side is permanently connected.

[Adrian Smith 1]

Last job before I went out the door was to fix the U/C collars. I use clear silicone sealant and temporarily tape the collars until dry.

[Adrian Smith 1]

OK so onto a mammoth soldering session this afternoon.

First job is the motor/ESC bullet connectors.

 

The next problem to overcome is the ESC wires to the pack connectors are a bit too short to feed through into the fuselage.

 

Looks like I am going to have extend them a tad.

[Adrian Smith 1]

Extended the positive side using a gold bullet connector where the anti spark connector serves as the on/off switch.

The negative (black) remains the same length to the anti spark connector which will remain closed at all times and taped with black insulating tape.

 

The full power train is now complete ready for installation and testing.

 

The series leads will of course plug into the lipos. 

[Peter Jenkins]

For the record Adrian, it is better to extend the AC 3 phase wiring to the motor than the DC supply wires between the battery and ESC.  Not sure what the magic numbers for the max length of the DC supply wires should not exceed.

 

I might have misunderstood what you meant but I just wondered why you have an anti spark connector on the black lead when you say you won't be disconnecting it.  It would be better on the red lead as that's the one you will be connecting when the pack is installed.  Alternatively, connect the red lead permanently - matters not in DC - and get the spark arrestor to do its job when you connect up.

[Tom Gaskin 1]

Conventional wisdom if for the battery to esc leads should be no more than 200mm. As Peter says the ESC to motor leads can be as long as you like. I have a Dornier 335 with about a metre between the rear motor and its' ESC.

 

Tom

Edited August 3, 2023 by Tom Gaskin 1
Wretched predictive text...

[Adrian Smith 1]

I hear you on extending the motor wires, Peter. However, on my large scale electrics I like the ESC to be in the airflow from the cowl openings to keep it cool. The further back in the fuselage I put it there is effectively no airflow, hence my usual if not conventional practise of extending power pack/ESC  wires slightly so I can keep the ESC nearer the front opening. Contrary to what I wrote in the previous post, the black/negative connector is NOT anti spark as that is only on the red/positive side which as you say is the on/off switch. 

 

Tom, thanks for your comments. I note you say "conventional wisdom" relating to the 200mm ESC leads length. I am still unaware of what the actual factual evidence is for that length, in fact I seem to remember reading somewhere that it matters not, but I can't remember where so I stand corrected. 

I have used this method on all my large scale electrics for sometime and I can honestly say I haven't noticed anything detrimental occurring. I have measured the length of the wires and they are around 250mm so I am not going to lose any sleep over it. Well noted though. 

 

[Tom Gaskin 1]

Adrian,

Ron Van Sommeren has a worthwhile thread on rcgroups on the wire length question that is still relevent today despite the age of the thread.

https://www.rcgroups.com/forums/showthread.php?952523-too-long-battery-wires-will-kill-ESC-over-time-precautions-solutions-workarounds

 

It seems to me that only 'quality' esc's state a battery wire limitation (Jeti quote the 200 mm length) while other sellers ignore it altogether

 

Tom

 

 

 

[Adrian Smith 1]

Thanks for your research,Tom, I will give it a read.  My ESC is a HobbyWing which I consider to be "Quality" and it makes no mention of battery wire length. The wires on ESC are barely 100 mm which sort of implies you are likely to have to add to them.

 

[GBG]

Just checked some of my EDF's as they tend to have longer battery leads. Most are in the range of 200 to 250mm. One which has a Hobbywing esc has a battery lead length of 400mm. Model flies fine with no obvious esc problems.