Lee Smalley Posted January 22, 2013 Share Posted January 22, 2013 yeah read good reports about them off the web, they really do seem to cheap to be that good, but the reports i have read do seem to be holding up, personally i (and this is what i did with the alturn) would buy a few and shove them on rudders or flaps etc and see if they last! Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted February 15, 2013 Share Posted February 15, 2013 Well I ordered a couple of the Corona DS558HV servos to have a look at & they have just arrived....... Initial impressions are good......running them on a 2S LiFe pack they seem smooth & powerful & quite quiet.. There is little or no backlash in the gears. The mounting lugs are quite thick & look man enough for the job. Inside the pcb is well supported by being soldered directly to solid terminals on the motor. The gears look nice & cleanly cut with a good "dollop" of grease in there. All gears are metal too....no plastic first gears (whats that about then!!!???). The output shaft is supported in two ballraces & there are brass inserts in the case top for the gear spindles.... The only downside is the moulding of the outer casing.....I'm nitpicking here but perhaps they are not quite as crisp as some of the well established brands.... Overall then they look very good......they are destined for duty on a couple of models as rudder servos so we'll see how they perform...... Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 15, 2013 Share Posted February 15, 2013 Oddly enough, Steve, I ordered one after you mentioned them before and flew it (on the rudder) yesterday. The rudder seems pretty powerful - I'm tending to overcorrect even with 100% expo - I think it should knife edge loop (I managed to get somewhere near the first half of one yesterday but went a bit screwy at the top ) but I'm still getting used to the model. One of my clubmates took a video of one flight yesterday if you're interested: You might notice that I've mildly scaled up the cockpit as I didn't lime the supplied plastic "pyramid" and rather undersized (and cowardly - he tried to bale out on the first flight) pilot. P.S. The cameraman had a new camera and still getting used to the vagaries of its autofocus and zoom. Edited By Martin Harris on 15/02/2013 20:42:43 Quote Link to comment Share on other sites More sharing options...
John Allen Posted February 15, 2013 Share Posted February 15, 2013 I had actually plumped for the Corona DS538HV for the Pitts Python, but have now acquired a set of Turnigy 1257tg (rebadged PowerHD 8309tg) for it instead. Although I might swap the PowerHD 7150's from the Extra 330L, and put the 1257tg's in it instead, and the 7150mg's into the Python. I ordered a Soar 40 from HobbyKing UK (silly cheap), and will try the Corona's in it instead. If they hold up ok, I may replace more of my old Futaba 3001/3003/3004's with them, especially as I'm switching to unregulated 6.6v LifePO4's, when I replace a NiMH. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted February 16, 2013 Share Posted February 16, 2013 Looks really good Martin......seems to have a good amount of power with the 180 up front.... Thats a pretty big muffler can you have on there too.... Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 16, 2013 Share Posted February 16, 2013 Stangely, the video makes it sound louder than in real life where it sounds rather good, in my opinion. Word of warning - I found that one of the canopy tabs had detached due to glue failurewhen I took it off after flying today - worth keeping an eye on their security... Quote Link to comment Share on other sites More sharing options...
John Allen Posted February 16, 2013 Share Posted February 16, 2013 I still haven't bought my Yak (did buy a littel BH Yak, and so much other stuff, it'll probably be a while), but now I know I need an ASP 180FS Flight looked fab with that engine. Thats a JustEngines super quiet silencer, yes? Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 16, 2013 Share Posted February 16, 2013 Yes - it's actually the Weston Super Quiet silencer as supplied by JE. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted February 16, 2013 Share Posted February 16, 2013 Is it particularly noisy on the standard muffler Martin? What size prop aee you using? Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 16, 2013 Share Posted February 16, 2013 I'm using an 18 x 10 which got through our noise test when it was in my Miles Atwood (30s racer) using an own design custom silencer, However, that model was of a much more sound deadening traditional construction with a fully enclosed engine and silencer. In the Yak, the same combination was giving something like 87 dB at 7 metres! I did get it through by using an add-on extension that I made for an ST91 but it was rather unsightly and seemed to add too much back pressure. I've been meaning to try a lower pitched prop the last couple of times I've been up to the field but flying and various other activities have got in the way. Although it will rev higher I'd like to see the effects of a less stalled prop... In the air, it seems quieter than many models that have got through the test without difficulty - frustrating, but as a committee member I have to abide by the rules at least as strictly as anyone else in the club! Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 22, 2013 Share Posted February 22, 2013 Further to your question Steve, I can't really say how noisy the standard muffler would be as I sold it with an ASP 120 which I bought the 180 to replace when I found the model it was in needed more power. I had a baffled 120 silencer which I thought would be more useful to keep than the standard silencer (which is listed as a quieter alternative to the standard 120 one) as I'd already built a customised exhaust for the model it was in. One thing that those interested in the 180 might bear in mind is that I am experiencing a rather high vibration level which has broken the glue joint on one of the canopy fixing lugs and yesterday I discovered that one of the front canopy moulding securing screws has worn the hole very badly so that the canopy made some very odd noises in flight. This is despite careful prop balancing and a precautionary change of (metal) spinner. I tried an 18 x 6 yesterday which got through the noise test OK but although the performance still seemed very good, the odd noises (found to be from the canopy after I landed) made me curtail the flight early! I suspect that I'm going to find the 18 x 6 much better overall as it should improve the vertical response and it was never lacking in level flight speed, to say the least. I think the engine will enjoy being unloaded a bit as well. Edited By Martin Harris on 22/02/2013 11:40:03 Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted February 22, 2013 Share Posted February 22, 2013 I guess a 30cc single cylinder engine will always vibrate a fair bit......might the higher revs on the less "pitchy" prop make things worse I wonder...... Do I recall reading that you had an anti vibe mount for the engine too? Quote Link to comment Share on other sites More sharing options...
steve-richards Posted February 22, 2013 Share Posted February 22, 2013 Very nice model i have a saito 125 in mine Good luck with yours Quote Link to comment Share on other sites More sharing options...
steve-richards Posted February 22, 2013 Share Posted February 22, 2013 I had a duplo mount put on mine to stop the viberation Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 22, 2013 Share Posted February 22, 2013 Posted by Steve Hargreaves - Moderator on 22/02/2013 12:11:40: I guess a 30cc single cylinder engine will always vibrate a fair bit......might the higher revs on the less "pitchy" prop make things worse I wonder...... Do I recall reading that you had an anti vibe mount for the engine too? Quite possibly - although are you assuming I'm at full revs all the time, Steve....? I suspect there will be critical RPMs at various harmonics of the airframe anyway - many full size aircraft have "avoid" bands which I believe restrict continuous operation in these areas. Yes - I have a Dubro resilient mount but I'm aware that these don't eliminate vibration, just modify its characteristics. Quote Link to comment Share on other sites More sharing options...
steve-richards Posted February 22, 2013 Share Posted February 22, 2013 Yes Martin i had to modify mine a little to reduce it not stop it and i didnt use the red spinner eather otherwise a very good model when weather improves Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted February 22, 2013 Share Posted February 22, 2013 Posted by Martin Harris on 22/02/2013 13:19:57: Posted by Steve Hargreaves - Moderator on 22/02/2013 12:11:40: I guess a 30cc single cylinder engine will always vibrate a fair bit......might the higher revs on the less "pitchy" prop make things worse I wonder...... Do I recall reading that you had an anti vibe mount for the engine too? Quite possibly - although are you assuming I'm at full revs all the time, Steve....? Ah...good point Martin........I guess you only need full power for the up diddly up up parts... Quote Link to comment Share on other sites More sharing options...
karl grey Posted May 8, 2013 Share Posted May 8, 2013 I've just finished building my kit of this model and fitted a moki 135 up the business end. Only issue i have is setting the CoG. Is the manual correct with 7-8cm from leading at wing tip or is it safer to go with the wing tube, after reading many posts regarding the CoG issue i'm still none the wiser so if anyone with this model could kindly confirm the correct place i'd be very grateful Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted May 9, 2013 Share Posted May 9, 2013 I set my C of G at the "book value" but due to the additional silencing and engine mounting mods it seems to have crept forward so now it is on the main spar which is about 3/4 of an inch forward of the marks I made originally. They were about 55mm from the front of the canopy cutout. My batteries (2 x 1100 mAh 6.6v LiFes) are mounted on a piece of balsa, retained by the rear edge of the canopy, which pushes in to leave them just in front of the fin in order to get the C of G somewhere about correct. All I can say is that it feels just right to me at the position it is - flick manouevres and spins are positive and inverted flight is nicely neutral with very little down elevator required, making point rolls, for example, a doddle. Interesting that you've seen this position recommended... One thing which could be relevant - last time I flew it I was doing a "silly" 90 degree sideslip approach from a deliberately ridiculously high starting point and it flicked into an unexpected spin with no warning - luckily with enough height to recover. 2 seconds later and it might not have been a happy ending so proceed backwards with the C of G with caution if you want to experiment! Edited By Martin Harris on 09/05/2013 12:43:57 Quote Link to comment Share on other sites More sharing options...
karl grey Posted May 9, 2013 Share Posted May 9, 2013 Thank you for that info Martin, I've currenlty gone with the CoG at the front edge of the wing tube. Fitted a moki 135 on a radial mount with jr 591 servos on control surfaces and trying out a power hd 1501 on the rudder, running 4.8v 2500 battery which is housed in a box mounted on longeron spars just above where the tubing for the pull pull starts, this is giving me a slightly nose heavy to start out with but will use caution if and when i come to experiment later. lll Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted May 9, 2013 Share Posted May 9, 2013 Mine comes out (roughly) on the centreline of the spar tube... Quote Link to comment Share on other sites More sharing options...
kartika karya Posted September 3, 2013 Share Posted September 3, 2013 Hi all, My seagull Yak 54 was maiden flown, Total weight 4587 gr, actual CoG is 120 mm aft LE (or 22% MAC) at root using DLE 20 cc engine and china product 16 x 6 propeller. Nice fly for initial maiden flight but still "nose heavy" a bit and too much power (just 0.25 throttle stick). Depent on : **LINK** the ideal CoG at 136 mm aft LE( 29.8 % MAC) at root. Best regards, Kartika. Edited By Chris Bott - Moderator on 03/09/2013 08:03:22 Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted September 3, 2013 Share Posted September 3, 2013 Hi Kartika, welcome to the forum. That link looks like a useful C/G calculator, thanks. Quote Link to comment Share on other sites More sharing options...
Paul Adams Posted September 3, 2013 Share Posted September 3, 2013 I always check the C of G setting using this calculator and it’s never let me down, unlike the measurements supplied with many ARTF, kits and Plans.>> I have a OS 120 2 stroke in mine, and power is not a problem, but wish I had used a petrol engine due to the heavy fuel use and the oily residue from the exhaust.>> Only problem I have had with the Yak so far has been the engine cowling securing which due to the size of the cowl keep vibrating loose especially since they are not screwed into much. I have resulted in fitting wooden blocks to the front bulkhead and then fitting proper screws into the blocks. It has never vibrated loose since.>> The only other tip I would say is to blank off at least 50% of the front of the cowl to direct the airflow over the cylinder head, otherwise it will overheat (insufficient exit holes for size of intake).>> Brilliant model to fly though. >> Quote Link to comment Share on other sites More sharing options...
JimmyBH Posted September 3, 2013 Share Posted September 3, 2013 Finally flew mine last weekend, went with the DLE20 and 17x6 APC prop (will swap to a wooden prop I recon - will look a lot nicer)....hardly went above half throttle and feels like there is a lot of power there if needed (brand new engine so wasnt pushing it). Shame though as my rudder servo packed up during the seond flight (brand new Hitec). i think it must have been under constant load and burnt out cause when I unpinned the pull pull wires one of them was wound up like an elastic band! I am very much a typical ARTF modeller and was surpised how many little tweaks and minor changes were needed to accomodate the DLE and ensure decent linkages alround - pleased though as I now know a lot more than when I started! Like Paul Adams did, I too built four blocks and placed them on the sidewalls to mout the Cowel, using four nylon cheese head screews and worked a treat! I am no expect on CofG, but the experienced chap who helped me build the Yak was confident the CofG was very much "as expected"...she was a little nose heavy in flight but nothing that needs much attention whilst I get a few bedding in fights under my belt Edited By JimmyBH on 03/09/2013 13:18:20 Edited By JimmyBH on 03/09/2013 13:19:35 Quote Link to comment Share on other sites More sharing options...
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