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
Spelling and forgot the link

[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.