Weston UK Capiche 50cc Revisited

[Adrian Smith 1]

Funnily enough, I looked back at a couple of my aerobat settings to see what's what.

My 91" Slick (Goldwing) has Elevators at 20mm +/-, Aileron 22mm+/- and Rudder 30mm +/- which seem ideal for me.

Sadly I can't find any record of what the throws are on my Sbach (Goldwing) which is also 50cc electrified, but I guess that are no too dissimilar to the Slick. 

[Adrian Smith 1]

Just for a comparison of the general area for the CoG range between the Capiche 50cc and Capiche 140 below.

 

Capiche 50 cc

 

 

Capiche 140. 

I am going to have to adapt  a couple of CoG balancing templates to use for the Capiche. Fortunately the CoG line matches the mid range point here on these templates.

 

 

 

 

 

 

That should do it when I get to doing that job.

 

[Adrian Smith 1]

I decided to position the RX and switch wiring first. I fed the throttle signal  wire down the fuselage to the RX first.

 

 

I then positioned the RX and switch next.

 

I am sort of hopeful the lipo power pack positioning will be roughly here.

 

I will have to see when I get to that.

 

[Adrian Smith 1]

I am a bit undecided about which prop to use. I have a 23x8 and a 24x8 which both fall within range, but I am not sure if I should go larger.

 

I will have a think about that.

I have a spare 3.5" spinner  that will need carving, although I think I might prefer one that has a back plate with a bolt that screws into the prop shaft. 

 

In the meantime I have cut a window in the fuselage floor to allow airflow though.

 

 

A bit more thought before moving to the CoG rig stage checking.

[Peter Jenkins]

Hi Adrian

 

On my latest F3A motor - the twin outrunners driving through concentric shafts - the props are 23 x 20.  The motors have a kv of 165.  On a 10S setup, max rpm is about 4,450 - I measured 99 amps and 3,600 W in the air.  In normal use, I usually see 80 amps and 2,700 W.

 

I see that your motor has a higher Kv and is powered by 12S but I think 24 x 8 is a bit on the low pitch size for precision aerobatics.  Try it and see though.

Edited September 22, 2023 by Peter Jenkins

[Adrian Smith 1]

I was beginning to think along those lines, Peter hence my hesitancy. My Sbach 342 (similar size and weight) runs the same motor using a 24x8 and seems to perform well although the same precision as F3A is not required. That said I wondered if I could improve performance if at all possible. I was thinking more along the lines of 24x9 or even 24x10. I am not sure what this would mean for the current draw at WOT. I have an interesting Pdf document that I have downloaded on these specific motors which examines the motor characteristics/efficiency of WOT on different props/voltages etc using a graph and tables. I can't work out how to reproduce it here otherwise I would believe me 😒

 

[Adrian Smith 1]

Tried again but failed!

 

 

 

 

Edited September 23, 2023 by Adrian Smith 1

[Peter Jenkins]

Hi Adrian

 

I use a 3rd party telemetry product made by SM Modelbau called a Unisens-E.  This is rated up to 280 A current so should be suitable for your use.  It is a very small device that fits between the battery and the ESC.  It provides real time capture and display on your Tx screen of current draw, voltage, rpm, height and a few other functions.  It's greatest use is to provide what is actually happening in the air.  The display is real time but there is a function to provide max and min values recorded in flight.  You can use it to display capacity remaining in the flight pack.  I use an alarm that triggers when I have 900 mAh remaining in the pack.  You can, of course, use the output when on the ground.

 

There is another product called UniLog 2 that is slightly larger and incorporates a micro SD card so that every flight has data recorded that you can then download and keep to compare over time.  I've not used this as I am more interested in the real time display as well as the max min recorded.  

 

With either, the guesswork is removed and you can either get someone to look at the in flight readings or glance down yourself to see what's happening.

 

At Euro 66 for the Unisens-E and Euro 99 for the Unilog 2, they are excellent devices and even if your radio provides onboard sensors, this sensor is both small and light as well as being designed to interface with most of today's radio brands.  The radio brands the products work with are specified in the description of them.

 

Here's a photo of the Unisens-E in my Anthem.  To give the photo size, those are 4 mm bullets.  On the left hand picture, you can see a thin white wire that is soldered to the yellow 3 phase connection and on the RHS you can see the white wire terminating in a plug into the Unisens-E.  The white wire gives rpm.  The small black wire connects between the Unisens-E on the positive terminal with the negative terminal to give voltage and the current is measured as a clamp meter would as it runs through the red wire that goes through the Unisens-E.  There is also a height measuring capability although how it does that I do not know.  It tends to zero itself on start up.  You can also set a variometer function and get it to alarm at different climb and sink rates.

 

By setting the pack capacity the system will decrement charge from the time you connect the battery and start using it.  Again, you can set alarms for charge remaining without needing to look at the output.  

 

There is a 4 wire plug to carry the usual signal, positive and negative and a second signal.  The second signal wire provides the max/min function and needs to be plugged into a spare channel in the Rx.  I find the Unisens-E invaluable when checking over a new model setup.  Thereafter, the max height readout is useful to let me know if I stay in or went out of the box, and the capacity alarm is helpful on a high wind day when more capacity is used up.  Generally, an 8 min schedule flight consumes about 3,000 mAh.  On a windy day this can go up by 500-800 mAh so as I use 4,800 mAh packs it is close to setting off the alarm which is set for 900 mAh remaining.

 

Hope that helps with your deliberations.

 

  

 

[Adrian Smith 1]

Interesting looking at your set up which is much more sophisticated than what I use. I have an in line ammeter (up to 200A) which stores the current draw readings for one flight then resets when the juice is turned off. However, I do use it on the ground with a new model although I appreciate those conditions are somewhat different in the air.

It will be good to experiment, however. Thanks for the illustrations though, Peter. 

[Adrian Smith 1]

I had a testing afternoon today to try and arrange the internals to achieve the correct CoG. I got her up on the rig an it was quickly evident that the power packs need to be right upfront. I suppose I am not surprised given that  she is designed for a petrol engine plus tunnel exhaust. 

 

Even with the lipos up front I still had to balance an 8oz weight on the nose to achieve a slight nose down attitude.

 

 

Time for rethink. First off I am going to have to build a shelf for the lipos to sit on at the front.

 

I have had a change of plan over the spinner as a result and will use an alloy one as opposed to the plastic one I had envisaged. That will give me an extra 2oz upfront.

In the meantime I found some 1/4" ply for the shelf.

 

The dimensions required are 10.5 cms width and 13.5 cms length.

 

 

 

 

 

Edited September 28, 2023 by Adrian Smith 1

[Adrian Smith 1]

On to the shaping using hard balsa triangle stock for the rails.

 

 

I am going to have to notch the shelf to accommodate the velcro strapping.

 

Like so ....

 

The shelf weighs around 2 oz therefore added to the extra 2oz from the spinner gives me 4oz of the potential 8oz required.My old woodwork teacher wouldn't be too impressed with that effort, but it is what it is. I am also going to fix the rails across the fuselage rather than along it  so as to accommodate the velcro strapping. 

One thing's for sure I will need to reconsider the elevator throws by reducing them particularly if the plane is still a bit tail heavy. I am thinking I may have to add 4oz of weight under the tray to help achieve the correct CoG. Anyway I will finish the shelf at the next visit.

[Peter Jenkins]

Can you get hold of a spinner with a heavy backplate Adrian?

[Adrian Smith 1]

Well the alloy spinner is a 3.5" job with metal backplate I am not sure if I can get anything heavier than that. Probably need to have look round, Peter.

Edited September 28, 2023 by Adrian Smith 1

[Adrian Smith 1]

Back after an extended holiday in warmer climes. Pleased to see the maize was cut down in my absence.

 

Sadly, I only had a short time in the work shop because the trip switch to the consumer unit kept tripping. Bit of an occupational hazard in ancient farm yard buildings. An electrician is required. Anyway what I did get done was to sort out the alloy spinner and shape the cut outs.

 

 

 

I managed to partially finish the power pack extension platform before the lights went out for good.

 

 

I fitted the velcro strips and then put a small screw in underneath to keep the velcro steady.

 

 I had to leave it at that and clear up using my iPhone torch! Hopefully things will be restored in the near future. Possibly flying on Wednesday though.

 

[Adrian Smith 1]

Lights back on so down to business. 

I finished off the power pack extension platform and add velcro strapping.

 

Test fitted the packs.

 

Bit of a tight fit. However, there is another problem that needs addressing. The ESC wires foul on the power packs adding to difficulty in installing the lipos. Bit of head scratching here. The wires comes through the middle of the fuselage which is not ideal given where the power packs need to be to get anywhere near the correct CoG. I am thinking there may be a way of feeding them along each side of the fuselage sides as there is a void here. It would mean the cowl coming off and fresh holes to be drilled into the ply facing where the motor box is mounted. It might even mean changing the wiring lengths. I hope not, but it all needs to be done properly. In the mean time the RX battery will sit just behind the power packs.

 

[Adrian Smith 1]

All my Dualsky 50-60cc electric motors fly well with a 23x8 Foxy wooden prop. However, I thought I would buy a 23x12 Foxy prop to see what the difference is.

 

I have found them darn good props at a reasonable price. The hub will have to be drilled out with four holes for the prop driver fixing. I will probably sort out the ESC wiring positioning first before embarking on the prop preparation. 

[Peter Jenkins]

Hi Adrian, you might find it easier to manipulate the packs by replacing the velcro on the battery tray with some non-slip matting.  That's what I've been using for the past 5 years.  It works very well provided you remember to strap up the 2 retaining straps!

[Adrian Smith 1]

That's interesting Peter. Sounds like a good idea. Can you tell me where you source it from? Thanks.

[Philip Lewis 3]

Poundland, B and M and shops like that, often called non slip draw liner, if you can't find it locally then E bay is your friend, I've been using it for years, never had a battery move yet! 

[Adrian Smith 1]

Thank you Philip. That's pointed me in the right direction! 👍

[Peter Jenkins]

Thanks Phil.

 

I have enough for another 10 aircraft Adrian as the roll is quite big!

[Adrian Smith 1]

I just had time to size up the modification before I went flying.

Under the motor box there are two side holes that should lead to the side voids given a bit of judicious drilling.

 

I should be able feed the wires through hopefully so they don't foul on the batteries.

 

While I am about it I am thinking of removing the wood pillars between the choke and throttle servo cutouts thereby making securing with velcro strips easier. I don't think doing that will cause a structural problem. Hopefully not.

 

I will it some more thought and tackle it next week.

[Peter Jenkins]

Looking at your proposal Adrian, the two "wood pillars" add little to the strength of that former.  If you are concerned and there is space underneath to clear the pack, add a vertical ply member across the full width of the fuselage - 5 mm wide should be sufficient.  That will provide a very strong T beam construction that would probably be weight neutral if remove the ply webs you have identified.  Just a thought.

[Adrian Smith 1]

Yes, Peter that is a good option. I will have look at that next week. Normally I am a bit reticent to go the "whole hog" on modifications if I can avoid it, but in this case I doubt I have much option. I will report back. 

[Adrian Smith 1]

At last I feel as though I have made progress! It was good I didn't rush into the wiring modifications as an alternative method revealed itself. It became clear I could just drill through F1 behind the left of the motor box to accommodate the power pack wires. I started by drilling a pilot hole to make sure I was in the right place.

 

Next used a 12mm drill bit to make the final hole.

 

I found the right size grommet and cyanoed it in after feeding the wires through.