John Roberts 9
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Everything posted by John Roberts 9
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Hi Roy I used a 35mm spinner on mine with 7 x 4 prop blades but I used a more powerful motor. However I think the motor needs a bigger prop to produce its full power and I am waiting for the postie to deliver an 8 x 4 and an 8 x 6 prop. Once they arrive I will do some more tests with the watt meter to see which is most suitable. Cheers, John
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First Round Voting
John Roberts 9 replied to Biggles' Elder Brother - Moderator's topic in The 2014 Mass Build
1. Rat Out of Hell 2. Mini Jazz 3. Evolution Micro Fusion 4. Avicraft Frantic 5. E2K -
Hi Roy The one I used was supplied by Purple Power (4 Max) Link Probably not the cheapest on earth but very light, nice quality and a whole range of prop blade sizes available. Cheers, John
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2014 Mass Build - Candidate Model Nominations
John Roberts 9 replied to Martyn K's topic in The 2014 Mass Build
Rat Out of Hell or the Wasp E2K Link for me! Cheers, John -
Help Please: So What Is It Then?
John Roberts 9 replied to John Roberts 9's topic in Sport, Aerobatic and 3D kits
Hello Mark, Thanks very much indeed for going to all that time and trouble to find this for me . The specs are incredibly close to mine and the layout & construction details are virtually identical. The same kit with a different label on the front I wonder? It will be an easy job now to find a suitable motor & speed controller. Thanks once again for your help with this which is genuinely appreciated. Cheers, John -
Help Please: So What Is It Then?
John Roberts 9 replied to John Roberts 9's topic in Sport, Aerobatic and 3D kits
Hi Mark Thanks for the response I too thought that it was a Yak 54 but despite quite a lengthy search on the web I haven't been able to find this particular kit. It is certainly a popular aircraft to be modelled. I have found big ones, small ones, foam ones, balsa ones, some with an identical colour scheme to mine and others with totally different decoration but none that seem to match it perfectly in terms of apearance & dimensions. Ultimately it doesn't really matter if I can't specifically identify the manufacturer but I would nevertheless very much appreciate some guidance on a suitable electric powertrain for this size & type of model if anyone is able to assist please? Thanks, John -
Hello A friend gave me this model recently and although I have the instruction manual it is unclear as to precisely what model it is and who it was made by. It may be an X-Tech kit originally supplied by ProBuild, Blandform Forum. They were very polite & helpful when I rang them and they *thought* it might be a (now discontinued) Yak 63 (does that even exist?). Is anyone able to definitively identify it please? The airframe, including servos, but without power plant weighs just over 2Kgs. Wingspan is 1500mm and fuselage length of 1360mm. The manual suggests a 2 stroke engine of 52 - 70 size or 4 stroke 63 - 70 size. It previously had a oily YS it it btw. I would like to put an electric motor in it and, whilst the manual says that it is suitable for electric power, it doesn't give any specifics. The ProBuild guys (understandably) didn't really want to commit themselves on this question but suggested that a 400Kv motor on 6s lipos of around 1500 - 1700 watts *might* be suitable. How does this set up sound? It would be very helpful to receive some specific motor suggestions (say from HK / Purple Power / BRC etc) so that I can compare specs & prices etc. Although I already have a number of leccy planes this one is a step up in terms of size & power for me so I am outside my comfort zone and would welcome advice about suitable powertrains etc. Thanks, John
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Hi Chris The motor is rated at 1400Kv. Looking at some of the comments from other buyers on the HK web site it looks like they have achieved better results with an 8 x 4 prop so I have just ordered an 8 x 4 set and an 8 x 6 set from Purple Power. Good job they are only a couple of quid each! The ESC (BRC supplied) came out of another model and was working correctly up to being swapped out. Its possible that it has just developed a fault but probably unlikely. Lets see what the prop changes bring. Cheers, John
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Interesting! A power check using the 800mah battery shows that flat out the motor draws 10A / 116watts (using the recommended 7 x 4 prop) which is roughly half of the rating quoted by HK. Another check with a 2200 3s battery and using 4mm connectors throughout produced almost identical figures........so it isn't the small battery & connectors. I guess that the motor could be a dud or perhaps the 7 x 4 folding prop might be horribly inefficient or even the ESC is wilting (altho in my experience they either work or they don't). I imagine the only way to work it out is to experiment with different prop sizes and swapping out the motor and ESC until, by elimination, I find the culprit...................bit of a pain and could be costly. Cheers, John
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It certainly does sound as if I have an issue somewhere in the powertrain. My model weighs in at 13 ounces too and I am using a 7 x 4 folding prop (from Purple Power). The battery has only had a handful of discharge/recharge cycles (definitely not a tired worn out example) and is in full health according to my test meter. The motor is a brand new item from Hobby King. The only significant difference in our builds is that mine has a longer boom but I can't see that being of any consequence in this respect. I will do a power test later this afternoon and see what that reveals. Cheers, John Edited By John Roberts 9 on 27/09/2013 12:36:44
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Hello I have had a chance to fly mine a few more times now and very pleasant it is too! Oddly the only area of slight disappointment is the modest amount of power. The 28mm HK motor is supposed to deliver 205 watts on a 3s battery on a 7 x 4 prop and, although I havent checked it on a watt meter yet, it feels as though its only delivering half this amount at best. The model doesn't balloon, it really struggles to do a lazy loop and it has nothing like unlimited vertical so something is amiss in the power delivery department for sure. My suspicion is that the GensAce battery (800mah 3s 30C), which uses tiny little 2mm gold bullet connectors, is struggling to provide sufficient current when I open the throttle wide. I need to make up some connector adapters later today so that I can do a power test with my watt meter (the meter uses 4mm connectors hence the need for adapters so that I can hook it up to the 2mm battery connectors). Cheers, John
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Hello Last year I bought a secondhand Precision Aerobatics Katana MD but I have only recently started flying it. The instruction manual says that "the centre of gravity range is 95mm-103mm measured from the leading edge of the wing root" and goes on to suggest that the optimum CG is at 101mm. Inittially I set the model at 101mm but it was clearly tail heavy in flight. Things were better at the forward most position of 95mm but the aircraft still felt & looked tail heavy in flight. I need to experiment more with the battery postion but I think that I will probably end up with a balance point around 90mm-92mm. Has anybody else experienced similar issues with the same model? I wondered at one point if there was a misprint/mistake in the owners manual or maybe there is some set up trick that I have missed? Any advice or suggestions gratefully received. Thanks, John
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Mine had a successful maiden flight today . The weather here was rather murky with low cloud & poor visibility so I could really only pootle around. It needed just a couple of clicks of trim to get it flying straight and level. Perhaps surprisingly it didn't seem overpowered and showed no tendencies to "balloon" when opening the throttle. I would speculate that the longer boom on mine (20 inches) perhaps makes it less sensitive to throttle application? It also has a nice gentle sink rate and can be very slowly floated in for a landing requiring only a tiny whiff of elevator to achieve a gentle touch down. I only got one flight due to the poor weather but after 7 minutes of tootling around my 3s 800mah battery had 65% remaining. With more altitude I imagine that 20 minute flights will be easily achievable. Cheers, John Edited By John Roberts 9 on 23/09/2013 15:06:06
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Thanks for the report back on your maiden flight. Mine will get its first run out on Monday or Tuesday. Your thoughts on downthrust are particularly interesting especially as my build is both lighter (13 ounces) and more powerful (200 watts) than yours. I am clearly going to have to exercise some throttle control !! I will report back next week. Cheers, John
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2014 Mass Build - Discussion about model choices
John Roberts 9 replied to Martyn K's topic in The 2014 Mass Build
Hello, I think that the availability of a parts kit is likely to bring in more first time builders. I believe that many people (and not just newbie builders) find it daunting to build from plans. From the suggestions made so far my preferences would be a slightly scaled down Rat Out of Hell (the odd ball looks appeal to me for some reason) or an E2K model (but no speed competition for the reasons already set out in this thread). Wasp E2K Cheers, John -
Looks great Caveman . So how did you manage to completely hide the servo? Very neat! It certainly looks more attractive than my solution with the servo, rods & horns externally mounted on top of the wing. Cheers, John
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Thanks Chris & Steve The forecast up here in "sunny" Scotland suggests it might be a little breezy over the weekend but after that it looks like light winds for several days so I will report back on the maiden early next week. The purple covering is just what I had left over from repairs to a damaged PA Addiction generously given to me by a friend a few weeks ago. Cheers, John
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Hello Well here is my finished model: Completed weight, including a 3s 800mah Gens Ace Lipo is 13 ounces. I also found the model to be a little nose heavy and I have ended up with a carbon boom that measures 20 inches from the rear of the fuselage up to the leading edge of the tail feathers. I used a cheapo Hobby King motor D2826-10 (under £7) which is rated at 200 watts on 3s with a 7 x 4 prop. Link To simplify the build I omitted the dihedral and I also mounted the aileron servo on top of the wing. This solution isn't nearly as elegant as Chris's but made for simpler construction and avoided having the torque rods hanging down into the cramped fuselage compartment where they would almost certainly conflict with the rear wing mounting plate. Lots more photos in my album for anyone who might be interested. Thanks to Chris for a nice design and a fun build. Just waiting for a nice calm day now for the maiden. Cheers, John
