Tim Ballinger Posted December 23, 2019 Share Posted December 23, 2019 Barry, I’m just guessing here but the extra thrust of the 4S version can only come from increased airflow relative to the 3S , either bigger flow area or higher velocity. In the static case where the airflow starts from rest it probably needs even more intake area to achieve the spec thrust. Why does it not even match the 3S thrust for the same size? Anybody’s guess but the fan aerodynamics are probably quite different and possibly operating with heavy losses at non design flows. Not sure there is room to get a bigger intake in the model so unless you can achieve flying speed and get a higher entry speed the 4S could be a noose round it’s neck. If you can get it flying by loosing weight of course you might end up with a rocket! Incidentally I did check my current values with a different sensor and my 3S fan is definitely pulling 42A with a newly charged battery which is what my tests were done with. And as noted at the start of this para I am just guessing as to why your thrust values are so low. Very happy if you find a simpler solution like a defective motor. Tim Quote Link to comment Share on other sites More sharing options...
Tim Ballinger Posted December 24, 2019 Share Posted December 24, 2019 Oh and a belated thanks to Dave Chatterton for his idea of joining the gnat wings in situ. Had the anhedral and brace set up on the bench and as the brace was a tight fit I tried manoeuvring the wings into position in one piece. Possible but I felt in danger of breaking the thin parts of the fuselage side so adopted for Daves approach of pushing each side in separately. Rather than epoxy and since I pretty much used cyano exclusively to build this model, wicking thin cyano into the root join and around the brace provided a pretty instant and easy assembly. Again thanks fo4 suggesting the alternative. Thanks and Merry Xmas Quote Link to comment Share on other sites More sharing options...
Tim Ballinger Posted December 28, 2019 Share Posted December 28, 2019 Covering finished just decals to go. Currently 22.6 Oz. Quote Link to comment Share on other sites More sharing options...
martin collins 1 Posted December 28, 2019 Share Posted December 28, 2019 Very nice, looking forward to the flight report, starting mine next week.............. Quote Link to comment Share on other sites More sharing options...
Steve Nash 1 Posted December 28, 2019 Share Posted December 28, 2019 Looking good, Tim. been cutting out the formers and fuselage sides for my Gnat. Took quite a while, maybe I should have paid out for the Laser cut set from Tony. I brought the canopy though. Quote Link to comment Share on other sites More sharing options...
Tim Ballinger Posted December 29, 2019 Share Posted December 29, 2019 I always get more satisfaction having done my own cutting out. Feels more like ‘ I built that’ when I stand back and look at the finished model. If you know what I mean. Tim Quote Link to comment Share on other sites More sharing options...
Steve Nash 1 Posted December 29, 2019 Share Posted December 29, 2019 Yes I agree, it's definitely built by me when I cut them out. Did that for the Provost too. And it's a lot cheaper. I've just made a vacuum forming box too, so I can hopefully make my own canopies and intakes etc as well. Steve Edited By Steve Nash 1 on 29/12/2019 09:47:53 Quote Link to comment Share on other sites More sharing options...
Tim Ballinger Posted December 30, 2019 Share Posted December 30, 2019 Not ventured as far as vac forming yet except of course when I move the hot air gun too close to a fitted canopy.😪 Anyway RAE Gnat now finished in full livery. Final weight 22.78 oz or 646g , so pretty pleased with that. C.G. I found a little difficult to pin exactly but it’s as close to the plan as I can manage, so battery position duly marked with big black pen. I will take a trip down to our flying field this week and see if the water level is yet below ground. It is low lying so I am not holding my breath. All the best for the New Year Tim Quote Link to comment Share on other sites More sharing options...
Barry Buxton Posted December 30, 2019 Share Posted December 30, 2019 That looks very nice, looking forward to hearing how it flys. I received my new 4S FMS fan so did some basic testing on a quickly put together frame, the claim is 850g thrust, I added a thrust tube to the rig, the same as the gnat design, output diameter is ~40mm and measured 720g thrust, interestingly if I removed the thrust tube or opened it up on the rig to 50mm then the thrust went up to 780g. I now need to remove the fan from the plane, which could be interesting and see what that shows on the rig and swap them out. Still need to see how to get the weight down. as a matter of interest where is the battery placement in yours to balance it, with my 4S setup the battery is pretty much as far back as it will go without further modification. Quote Link to comment Share on other sites More sharing options...
Steve Adams Posted December 30, 2019 Share Posted December 30, 2019 Tim, That Gnat of yours in RAE colours looks absolutely stunning! I take my hat off to you Sir, I only wish the RCM&E back issues with the Gnat and Jet Provost hadn't of sold out so quick as the plans are expensive at £14.00 each! Kind Regards Steve Quote Link to comment Share on other sites More sharing options...
Tim Ballinger Posted December 31, 2019 Share Posted December 31, 2019 Thanks for the kind comments . Barry I will measure the battery position and post a pic later on today. Tim Quote Link to comment Share on other sites More sharing options...
Tim Ballinger Posted December 31, 2019 Share Posted December 31, 2019 Barry, The rear of my battery is 30 mm from the front of the hatch ( which is positioned as per the plan) or if you prefer 60mm in front of the cg line. Apologies pics are a bit dark as I forgot to put the lights or flash on. Think you can seen my black line just behind the battery. Tim Quote Link to comment Share on other sites More sharing options...
Dave Chatterton Posted January 1, 2020 Share Posted January 1, 2020 Tim That gnat of yours looks fantastic. Love the colour. Where did you get your letters from and also your pilots. I have started to build the hunter but stuck at the moment as the fan hasn’t arrived from bangood as yet. Happy New year to you. Regards Dave Quote Link to comment Share on other sites More sharing options...
Dave Chatterton Posted January 1, 2020 Share Posted January 1, 2020 Tim That gnat of yours looks fantastic. Love the colour. Where did you get your letters from and also your pilots. I have started to build the hunter but stuck at the moment as the fan hasn’t arrived from bangood as yet. Happy New year to you. Regards Dave Quote Link to comment Share on other sites More sharing options...
Tim Ballinger Posted January 1, 2020 Share Posted January 1, 2020 Thanks for the nice words Dave, I’m a cheapskate when it comes to decals. I print what I want , roundels letters/ numbers onto A4 vinyl from eBay. Then just cut them out with a scalpel. Unless it is white lettering I tend to print on clear vinyl but some stuff is better done on white. White lettering is a challenge because you have to print an outline and cut out individual letters. Perhaps I’ll splash out on a proper vinyl cutter one day!. Tim Quote Link to comment Share on other sites More sharing options...
Steve Jones 2 Posted January 5, 2020 Share Posted January 5, 2020 Great afternoon to start the year . Just love the Gnat Steve Quote Link to comment Share on other sites More sharing options...
Steve Jones 2 Posted January 5, 2020 Share Posted January 5, 2020 Joined by the Provost too Quote Link to comment Share on other sites More sharing options...
Steve Jones 2 Posted January 5, 2020 Share Posted January 5, 2020 PS .. great scheme on yours Tim !! Steve Quote Link to comment Share on other sites More sharing options...
Tim Ballinger Posted January 5, 2020 Share Posted January 5, 2020 Yours look pretty smart as well Steve. You must be blessed with better weather than me. Checked the field last Thursday and it is still almost liquid. If we had a week without rain it would help! Clearly I have not flown my gnat yet but I have set it up with the recommended control throws. Is that what you are using? Tim Quote Link to comment Share on other sites More sharing options...
i12fly Posted January 5, 2020 Share Posted January 5, 2020 Tim & Steve, beautiful Gnats, think I'll copy the yellow one -love the black fin (that's when I get to start it....) Quote Link to comment Share on other sites More sharing options...
Steve Adams Posted January 5, 2020 Share Posted January 5, 2020 Steve and Tim, Your Gnats are absolutely superb! Steve the Jet Provost is also awesome! Any of you guys have the plan for the Provost and Gnat I can beg, borrow, steal, buy or simply PDF, photo copy etc please? Many Thanks and Kind Regards Steve Quote Link to comment Share on other sites More sharing options...
Steve Jones 2 Posted January 5, 2020 Share Posted January 5, 2020 Tim not sure on exact throw measurements. I just set throws with 30% expo then rates at 100%, 75 and 50 then maiden on 75 so I can go up and down as required. with cog as plan then for me elevator was spot on but roll still a bit quick so I reduced. the model is quick and slippery so down not need high power compared to the provost but as small soon gets away to don’t go too far. In turns just watch the bank angle as a couple of time I have rolled too much and it tucked under. its a fantastic model to fly , soo smooth and quiet and cruises on half power on 3s set up enjoy !! steve Quote Link to comment Share on other sites More sharing options...
Tim Ballinger Posted January 6, 2020 Share Posted January 6, 2020 Cheers Steve, The thought of a small dot in the distance is my major concern with this model so we will see ( no pun intended !) Another week of rain forecast so it’s not coming this week. Tim Quote Link to comment Share on other sites More sharing options...
Tim Ballinger Posted January 6, 2020 Share Posted January 6, 2020 @Steve Adams, Steve, I don’t have the Provost plan yet and my magazine plan of the gnat is all cut up as I used it for cutting templates . Pity you missed the copies in the mag. Unless you are an avid canopy blower treat yourself to canopy and plan from Tony and you will save £3 on the deal. Sorry my curled up bits are not much use anymore. Tim Quote Link to comment Share on other sites More sharing options...
Dave Chatterton Posted January 11, 2020 Share Posted January 11, 2020 Hi guys is anyone started to build the TN hawker hunter yet? Quote Link to comment Share on other sites More sharing options...
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