MattyB Posted November 4, 2016 Share Posted November 4, 2016 Posted by Steve J on 04/11/2016 07:25:59: Posted by Adrian Smith 1 on 03/11/2016 20:08:19: for a separate battery rx power source using say a 2s lipo what mAh capacity would suggest? I would fit a 5A UBEC fed by the main battery or a 2S LiFe around 1000 mAh. I would also seriously consider installing telemetry to tell you how many mAhs you have used. Steve I would second fitting a separate UBEC plus an Ultraguard rather than a separate RX pack. Rationale is that such a setup is the actually lighter than a separate RX pack (which would need to be at least a 2S 800mah, whereas the Optiguard only uses a 450mah pack), and if either the main flight pack or the UBEC fails you will still maintain control (not the case if you forget to charge your RX pack for any reason). It is more expensive though. Edited By MattyB on 04/11/2016 15:46:28 Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted November 4, 2016 Author Share Posted November 4, 2016 Matty, I have ordered a 6amp UBEC from 4-Max which allows some voltage minimal voltage selection (enough for me) The next thing is, can I understand how to wire the UBEC in? I am an electrical numpty as I didn't take any notice of my physics lessons! Edited By Adrian Smith 1 on 04/11/2016 16:33:41 Quote Link to comment Share on other sites More sharing options...
MattyB Posted November 4, 2016 Share Posted November 4, 2016 Essentially the same as I described above for the separate RX pack and Digiswitch, but all fed from the main pack - 4-Max have a good explanation on their site. Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted November 4, 2016 Author Share Posted November 4, 2016 Good man, Matty got it one thanks. Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted November 8, 2016 Author Share Posted November 8, 2016 Now I know that the manual recommends this plane flies on a 6S 4500 -5000 mAh pack, but I have found some 5S 4500 mAh Lipos here. **LINK** Firstly, is the spec satisfactory to use in this case and will I notice any major difference in performance? Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted November 8, 2016 Share Posted November 8, 2016 Adrian It all depends on the kv of the motor. If you have a motor with a kv much below 500 then go for the 6S. If you have a motor with a kv or say 550 then a 5S will do the job. A 5S with a 480 kv will not give you the sort of vertical performance that you need in the Mythos. The difference in my Monolog 70 was that I could fly the FAI schedule with a 6S pack but struggled with flying large manoeuvres with the 5S pack. Currently, I'm using 5S packs with a 550 kv motor but, while adequate, it does not give the consistent power of a 6S driving the lower kv motor. In an aerobatic aircraft there is no substitute for power. You can always use part throttle if you end up with too much thrust but not vice versa - believe me, an slightly underpowered aerobatic aircraft is not nice to fly! Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted November 8, 2016 Share Posted November 8, 2016 Yep no fun on your Cuban 8 (no half roll) if you're struggling with the push over part Quote Link to comment Share on other sites More sharing options...
MattyB Posted November 8, 2016 Share Posted November 8, 2016 Posted by Adrian Smith 1 on 08/11/2016 09:17:44: Now I know that the manual recommends this plane flies on a 6S 4500 -5000 mAh pack, but I have found some 5S 4500 mAh Lipos here. **LINK** Firstly, is the spec satisfactory to use in this case and will I notice any major difference in performance? Sorry, but with the motor you have (A50-16S is 365Kv) you have to use 6S; you will be very underpowered for aerobatic flying on 5S with the recommended prop, and I doubt you have the ground clearance to prop it up and get back the thrust you have lost. Even if you did you would be pulling more amps so duration would be down. Besides, you could by 6S 4500 Zippy Compacts from HK for hardly any more money. Stick with the factory recommendation - it works! Edited By MattyB on 08/11/2016 18:52:16 Quote Link to comment Share on other sites More sharing options...
Josip Vrandecic -Mes Posted November 8, 2016 Share Posted November 8, 2016 ''In an aerobatic aircraft there is no substitute for power. You can always use part throttle if you end up with too much thrust but not vice versa - believe me, an slightly underpowered aerobatic aircraft is not nice to fly ! '' by : Peter Jenkins This is very true , Thanks alot Mr. Jenkins . Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted November 8, 2016 Author Share Posted November 8, 2016 Thanks Peter, Matty et al. It is what i suspected so you have kindly confirmed it. Also Matty, I fitted a UBEC today that I bought from 4-Max, tested it too all all seemed to work fine thanks. The help with the wiring issue was gratefully received. Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted December 3, 2016 Author Share Posted December 3, 2016 A quick update after 4 flights. Firstly, I have changed the rudder arrangement and removed the pull/pull cables and put the rudder servo in the rear of fuz in the outside cut out on the starboard side. This is because no matter what I did there was internal binding and the rudder would not centre by a long chalk from the right rudder movement. Interesting flying at times! Now that I have a pushrod set up the rudder is now completely positive. Given the transferring of weight to the rear I have now have bought some 4500 mAh 6s lipo to counteract this (I was using 3800s) and I will check the new position with these batteries and check the CoG next week. My other 3800s will be going into an Extreme Flight MX-S which I have recently bought and have started to build. I will probably post some photos of it when I get round to it. But first impressions are it is lovely aircraft. Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted December 4, 2016 Share Posted December 4, 2016 Adrian, it is well worth checking to see if you get very slightly different centre positions when returning a control surface from both sides. With an F3A aircraft, even the smallest deviation from a true neutral will make it difficult to fly consistently. On a 2 mtr Vanquish I had used Hitec 5654 (or something like that!) servos and when I asked a GB team member for his opinion on the aircraft's trim, he said it was impossible to trim the aircraft to get level flight from a vertical dive/climb as once the stick was centralised after pushing/pulling to horizontal, the aircraft would either climb or dive slightly. Having replaced the servos with another make, the control surface returned to exactly the same place when returning from either side. Believe it or not, that made a huge difference to the workload on the pilot! You could pull/push to horizontal and then not have to worry about the aircraft deviating from horizontal. Pilot workload in aerobatics should be expended on flying the manoeuvre and not struggling with the aircraft/equipment limitations. Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted December 4, 2016 Author Share Posted December 4, 2016 Dare I ask which make of servos you changed to that centred accurately, Peter? Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted December 4, 2016 Share Posted December 4, 2016 When I came into F3A I was told to use only Futaba or JR servos. I'm trying some Align servos which I have yet to fly but they seem to centre perfectly. These tend to be expensive but servos are what give the aircraft it's feel and are a vital link in aerobatics if you want to take things seriously. Some good reports on Savox as well. I have some Hitec TG 7000 series in my Capiche- these are 25 Kgmm servos recommended by Weston. You need to buy a Hitec gizmo to adjust resolution and deadband but I never did and both rudder and elevator do not centre repeatably. I know that in the IMAC world Hitec servos are popular but I can only speak from my own experience. You pays your money....... Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted December 4, 2016 Share Posted December 4, 2016 Sorry - trying to post from my smart phone! Edited By Peter Jenkins on 04/12/2016 17:34:00 Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted December 4, 2016 Share Posted December 4, 2016 Woops posted twice so deleted this one. Edited By Peter Jenkins on 04/12/2016 17:32:11 Quote Link to comment Share on other sites More sharing options...
Former Member Posted December 4, 2016 Share Posted December 4, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Colin Carpenter Posted December 4, 2016 Share Posted December 4, 2016 I changed from Hitec mg to Savox mg in my Mytho 30 which transformed the feel of the model. See the post on my build log. Still very pleased. Strangely enough , a secondhand Sebart Shark I bought has Hitec servos and this feels not as nice as the Mytho and Angel. Colin Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted December 4, 2016 Share Posted December 4, 2016 Percy, with many F3A pilots flying electric, they tend to use plastic geared servos which give better resolution than metal geared ones and, with the lack of vibration with electric power, the gear trains last well. It is far cheaper to replace the gear train than buy new servos as well. Most have now gone for the brushless variety of servos to extend life further. I know that often folk sell on the bare airframe and keep the servos, motor and ESC for their new ones. Those who are still flying YS powered birds may, no doubt, do as you suggest. Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted December 4, 2016 Share Posted December 4, 2016 Colin, interestingly, my experience of the low cost Hitec servos is that they centre better than their more expensive counterparts. Perhaps you really do need the Hitec servo management gizmo. Quote Link to comment Share on other sites More sharing options...
Rich too Posted December 6, 2016 Share Posted December 6, 2016 Yes, that is odd, on the FG website Hitec have a good following. Mind you, they do tend to be the top end ones! Quote Link to comment Share on other sites More sharing options...
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