Weston UK Capiche 50cc Revisited

[Adrian Smith 1]

Thanks, Peter I will try that. Something else I am considering is whether to add some EXPO. A couple of my aerobats have EXPO amounts dialled into the elevators and ailerons. There are no recommendations in the manual and I must admit I have never been truly convinced it helps me much. The amounts on my other aerobats range from -30 to -35 on the ailerons and -10 to -20 on the elevators. I have not added any to the rudder.  These seem a reasonable starting level for the Capiche so I may well give that a go. 

[Peter Jenkins]

I don't know of anyone who flies F3A competitively that doesn't use expo.  The main reason is to allow small control movements around neutral such that no one notices except the pilot and even they might not actually "see" the change but it affects the shape of the manoeuvre being flown or the straight line to be maintained in a cross wind.

 

Rudder, in particularly, has expo applied as you need a balance between small movements to allow minute control corrections to be made as well as having a good movement for stall turns.  I have to say that I use stick position switches to give me more movement of the rudder in stall turns.

 

My start point for ailerons and elevators is 10 deg each way and then I use around 20% expo.  I alter that to suit in the light of flying the aircraft.  The rudder I generally set to 25 deg each way with 30% expo and the aforementioned stick position switch to kick in extra rudder at full rudder stick deflection.  

[Adrian Smith 1]

Very interesting, Peter. As I tend employ more of a freestyle type of flying (not 3D) I probably can get away with larger EPAs. I take your point about active use of expo and I will add some too including on the rudder, probably not too dissimilar to the values you are using. 👍

[Philip Lewis 3]

Hi Adrian,

 

totally agree with what Peter said above, it allows minute corrections around centre more easily than without it, but I also think it's also to do with what you are used to, on my previous plane I copied another pilots settings, (after all he was world champion at the tiime) for both throw and expo, then when I assembled a new airframe I copied another well known pilots settings.

 

The first pilot used a lot of expo and the second nowhere near as much, on the second airframe whilst the throws felt fine the plane felt over sensitive to me, so I combined the two using the second pilots throws but with the expo settings that I had obviously got used to, using those settings now for two years so I also think the use of expo is also to do with what you, as a pilot are used to.

 

Incidentally (and whilst fully respecting that there is more than one way to skin a cat), for checking incidence I use a couple of these, they also have a magnetic base so you can put "fridge magnets from poundland" on the other side to hold them in place whilst you deflect ailerons and elevators, I find fine tuning in 0.1's of degrees much easier with these, I just can't really see in fracytions of a dgree with the robart meter.

 

With respect to the Robart meter (which I balance the above on), on the top of the bar to measure wing and tail incidence, to measure a greater span head to Wickes where you can get an aluminium strip for not a lot that pretty perfectly fits the plastic V mounts on the end of the Robart meter.

 

Just my tuppence worth in the hope that it helps.

 

Phil    

Edited November 27, 2023 by Philip Lewis 3
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[Philip Lewis 3]

Adrian,

 

Just another thought, using a lot of expo on an airframe of this type would, (I would think) give the pilot reasonable precision around centre whilst also allowing the larger throws used on these airframes at times.

 

Also bear in mind that the servo geometry itself, in effect, has negative expo built in as the deflection to the control surface during the first 30 degrees of arm travel is more than the second 30 degrees so the first part of expo is simply making the travel linear to the stock input.

[Adrian Smith 1]

Thank you, Philip I appreciate the time you have spent to outline your thoughts. My mantra is that you never stop learning (even after many years in this hobby)  and your tuppence worth is worth pounds in value for the advice! 😀 The tip about aluminium strip from Wickes is a great one and there is a store not far from me. I have been convinced now that I should use expo more readily on my aircraft and as the throws on the Capiche are quite wide she will be an ideal test bed. Your info on the servo geometry and it effect is particularly interesting. Many thanks to you and Peter for your very helpful feedback 👍

I will report back after the next flights when the temperature outside rises a bit more above freezing.

[Adrian Smith 1]

Final few adjustments before the next four flights.

Changed the prop to 23x12 and added expo.

 The rudder has -30 expo dialled in.

 

Both the elevators and ailerons have -20 expo.

 

 

Back down to the strip today and while it was quite dull the wind was right at 7mph down the strip for the next test flights.

 

The debrief is quite positive. The increase in timing and higher pitch/lower diameter prop has added more urge to performance and seems to have contributed to tidier aeros. I did notice a slight tail off in vertical performance but that's not surprising given the prop change although the stall turns were accomplished quite tidily. One thing that I will do is take a bit of weight out of the nose (reduce to 2 ounces from 4 ounces) as at the moment I have yet to get her to flat spin upright or inverted properly. I also think there is an argument to increase the EPA on the ailerons and elevators, although I think I might need to upgrade the servos slightly to give more bite in the aeros. That said she does perform them quite scale like if not as snappy as I would like. Anyway I still think she has been a good conversion project and I am very happy to keep flying her. 

[Adrian Smith 1]

As I had a few days to my kick heels in the work shop due to bad weather I decided to do a job on the Capiche I have been promising myself for a while. Partly due to my  wanting to save costs I put a set of HV Macgregor digital servos with a stalling reading of 21kg/cms at 8.4v in the Capiche. In my defence I was guided by the manual which was written for another time which featured a similar recommendation for most of the servos around this sort of level.  Well after a few flights I thought a move to more powerful HV 31kg/cms at 8.4v servos was more appropriate as per the rest of my 50-60cc squadron. Well in my musings in the W/S I notice my SkyWing 71' Edge 540 sporting an equivalent 35cc Dualsky motor on the front has these more powerful servos installed. A bit of an overkill possibly. Anyway the current servos in the Capiche would be just fine in the SkyWing Edge. Therefore for I set about swapping them out both planes this morning. It was a fiddly job mainly because of the elevators wires going through the fuselage, but in the  event it didn't take too long to do the job. I am looking forward to the next outing for both and I will report back here. 

[Adrian Smith 1]

I tried the more powerful servos today and was pleasantly pleased by the improved liveliness. I still have 2 oz of weight in the nose but I really don't think it needs to be there in future. That's the next job coupled with increasing the aileron EPAs slightly. 

[Adrian Smith 1]

I have had to bow to the inevitable today and decided to do a modification to allow easier inserting and removal of the power packs.

 

 

The easiest option is to remove the cross piece that holds the throttle and ignition servos for I/C variations. On close inspection is doesn't look like a structural support for the fuselage so I am going to give it a whirl.

 

 

Not a long job. I was originally concerned about heaving the lipos in and out and compromising battery connections before this mod. That should do it with a bit of luck. If needs be I can always put in a new cross piece further back which won't interrupt access.

[Peter Jenkins]

Hi Adrian

 

I've given up using velcro on the battery try as it can lead to a bit of a struggle to get the pack off it!  I just use a bit of non-slip rubber matting and velcro straps to hold the pack in place.

 

 

Cheers

 

Peter

[Adrian Smith 1]

I guess non-slip rubber matting is sourced from Amazon, Peter?

[Philip Lewis 3]

You can sometimes find it in places like Poundland. Home Bargains, B an M etc, after called draw liner but last time I wanted some I couldn't find any so E bay to the rescue it was. 

 

I haven't used velcro on batteries for years now, I always found it wasn't strong enough to do the job on its own still needing straps to be sure which just made it a more of a pain than it was worth anyway.

[Adrian Smith 1]

I will give it a go

[Peter Jenkins]

Phil beat me to it!  

[Peter Jenkins]

Just found the stuff I use.  It's here.

[Adrian Smith 1]

23 hours ago, Adrian Smith 1 said:

You know when you wish hadn't bothered to go flying - well I had one of those days 😒

With all the weather apps. indicating no rain this morning guess what? 

 

Drizzle, drizzle ......  

I waited in the car for 45 minutes waiting for clearance which it appeared to do. 

1minute 30 secs into the first flight the drizzle started again. Hasty landing and under cover again sharpish

Another 40 odd minutes passed and I could see signs of some sailors' trousers (blue sky) coming my way.

So after another patient wait up I go. Towards the end of the first flight I noticed some clattering of sorts coming from the Capiche. Another hasty landing to discover the following ....

 

 

 

 

 

After a quick repair with sellotape....

 

 

Off I go again with two fully completed flights. And here divine intervention occurred as a dark cloud cloud appeared  before the end of the third flight so down I come again and as fate would have it on taxiing back to the pilot area the motor quit not to be restarted again that morning. Phew, that was lucky! 😮

Decided to pack up and head to the work shop to investigate. That will be for another day. Hopefully it's not the ESC as it's brand new with only 3 flights on the clock. Got to check all the wiring to the motor and power packs along with the throttle signal lead which will take some time along with some testing with spare ESC kit. I will probably make a start tomorrow. I live to fight another day. 

 

 I think I have solved my motor cutout problem. Back to the work shop this morning to do a full check. First off I removed the prop and cowl. As a matter of trying to cut a corner I thought I would reinstall the power packs and try and run her again. Well low and behold all was well and performed as expected and ran the motor for some while at full chat. As a matter of course I did put a new throttle lead subsequent to the test. After a bit of thought I think it may be the ESC heat cut off was activated as I taxied after landing on the last flight and it reset overnight. Being a super-dooper HobbyWing 200A Platinum OPTO ESC it does state in the manual that there is a heat cut out to save you blowing the thing up and having to fork out £350+ for a new one. So why was this so? 

Firstly, I decided to cut a second large slot in the covering film on the underside where the pipe tunnel frame is. The second thing to do is make the air outflow area at the bottom of the cowl rear much bigger. Additionally, I reduced the motor timing down to 20 (from 22) and the start up force from 5 to 4 (max force is 7), all done from a programming box.

I feel a contributory factor to Thursday's issue is because as the weather was threatening at the time I undertook all flights in quite quick succession and not allowing sufficient cooling time. The turn back to taxi down the strip to the pilot with a burst of full throttle before cut out was the "straw that broke to camel's back" as the warm air on the cowl hadn't fully dissipated. When I fly next week I will see if this is the case after the modifications. 

[Peter Jenkins]

You might find glueing a piece of strng just in front of the exhadt hole will improve the airflow out.

Another good idea is to mount the ESC so the hestsink is just exposed to the airflow.

[Philip Lewis 3]

Or you could put a "propper" decent heatsink on it, the heatsinks they put on these are very minimal, hardly any mass to sink the heat into and very little fin are to carry it away either.

 

You can get blocks of aluminium heatsink on e bay and cut down to the size that you want easily and cleaply on e bay, what's left over will probably be enough for another or two, best way to attach is with a dedicated heat sink glue.

 

I doubt that about 15 grams would make that much difference to performance that's about what it would cost you.

 

 

[Peter Jenkins]

Good suggestion Phil.  I might buy some - just in case!

[Philip Lewis 3]

Quick footnote to my post above, when you take an existing heatsink off you will find (or should) heat transfer paste underneath, this is like a soft plasticine and should come off in a clean sheet, do not confuse with heat tranfer glue as the paste is neither sticky and nor does it ever set.

 

Also quite likely as heat transfer paste requires the heatsink to be mechanically held on it's been held on by them wrapping heatshrink around the ends, itself thereby preventing through movement of air through the fins of the heatsink, simply changing from a wrapped on heatsink to one held on with glue is likely to improve things a lot.  

[Adrian Smith 1]

Philip, that's a novel suggestion with the heat sink. I haven't come across that before. You learn something every day!

 

Peter, thanks for the suggestions and worth a try.

 

The thing that puzzles me is I have exactly the same configuration in my GoldWing 91" Slick with a Dualsky GA 8000 up from and 200A ESC as shown below. This has never been a problem before although I will concede the cowl internal area on the Slick is somewhat larger than the Capiche which has quite a slimline design.

The Slick :-

 

The Capiche:-

 

What I will add here is that I upgraded the Dualsky GA6000(50-60cc)  on the Capiche to fit the GA8000 (80cc-120cc) upfront and she now gives the lively performance I like. Particularly as the long moment on the fuselage which imparts a fair bit of extra weight. It also helps me to position the power packs much further back. Both Have the Hobbywing Platinum 200A HV OPTO ESC too. 

 

[Peter Jenkins]

The other thing to do is to make some structure to block air from taking the easy route past the bit you want cooled.  I've used depron to channel the air to the component I wan to be cooled.  This will force all the air coming into the cowl around the ESC while also speeding up the flow and further improving cooling.

[Philip Lewis 3]

I've also like Peter used both depron and very thin ply to direct the airflow to where I want it but in your case Adrian I'd make a much easier cheaper and straightforward suggestion, currently when you think about it the airflow comes in the front and exits that big hole at the back, at the best it skims over the esc but it pobably doesn;t really get into the fins, prop the back up, about 45 degress up if you can (I use foam blocks for this that come with the Falcon Propellers and Evo stik), the incoming airflow will thenhave to "hit" the Esc and you should get much better cooling.

 

To back up what you found the other day, a few years ago I did some testing of Esc Temps using a telemetry sensor, the ESC in the air using normal power settings the Esc would reach 32-34C but interestingly just land and the temprature would then continue to climb to about 42 C then gradually cool, and that's without any taxying, also bear in mind that say the ESC switches of at 80 C it might not switch back on again until considerably lower which could take a long time to reach especially on a warm day.

 

Electronics doesn't like heat and rund better when cooler, it really isn't a good idea to run right on the edge, the cooler the better, just look at PC CPU Coolers to get an idea, a PC CPU is about the same size as an ESC but just look at the size of some of the air coolers! 

Edited July 13, 2024 by Philip Lewis 3
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[Adrian Smith 1]

An interesting idea Philip. Indeed I think that to modify your idea and present a more secure way of mounting the ESC, I would built  an angled platform using a piece of liteply and and add two struts of different heights to form the 45degree angle. There is plenty of room under the motor box to do this and it would also provide a secure platform for me to mount the ESC. I usually put thickish rubber grommets under the mounting screws to provide a slight cushion.