Tim Kearsley Posted October 24, 2021 Share Posted October 24, 2021 Thanks chaps. Yes, I always fly with sunglasses Paul! Total flying weight, with a 4S, 4000mAh battery is 6.7lb. Is that reasonable? Quote Link to comment Share on other sites More sharing options...
Paul Johnson 4 Posted October 24, 2021 Share Posted October 24, 2021 Spot on. I would aim to move the C of G too at least 95mm back. Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted October 24, 2021 Share Posted October 24, 2021 Yeah, that's the worry to be honest. With a two-blade prop and plastic spinner - obviously a bit lighter than four blades and the ali spinner - the CG is around 95mm back. The battery box is extended and the battery as far back as it can go. I'm loath to add tail weight but I may have to. Quote Link to comment Share on other sites More sharing options...
Paul Johnson 4 Posted October 24, 2021 Share Posted October 24, 2021 Tim, I settled at 105 mm for C of G, the reason I mentioned 95 mm is it's safe but will be nose heavy, you'll tend to slide into the turns nose slighty down, just keep her high till you get the feel of it. My one is a joy to fly. Remember she is a warbird not a 3D ship so everything nice and smooth. Beats the FMS variant by a mile. Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted October 24, 2021 Share Posted October 24, 2021 OK Paul, noted, thank you. Would you add a bit of weight to the tail to bring it back a bit in my case? I haven't measured it yet with the four-blade and ali spinner but I'm guessing it will be between 90 and 95mm. Quote Link to comment Share on other sites More sharing options...
Paul Johnson 4 Posted October 24, 2021 Share Posted October 24, 2021 If you can get 95 mm have try. If you find, as I did, it needed a touch more. It wouldn't be a lot to move it by 5 mm. Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted October 25, 2021 Share Posted October 25, 2021 I'm planning to maiden the P51 on a two-blade prop, fitting the "precious" ali spinner and four-blader when it's all trimmed out and any teething problems are sorted. I've just run a full power check using a 13 X 8 prop and 4S, 4000 mAh battery and, surprisingly, it only draws around 32A, equating to about 470W. For a model weighing 6.7lb does that sound adequate? It's about 70W per lb which doesn't sound a lot. Anyone measured the current draw with the 14 X 8 four-blade setup? I should add I'm using an NTM Propdrive 5050 motor (580kV). Quote Link to comment Share on other sites More sharing options...
Paul Johnson 4 Posted October 25, 2021 Share Posted October 25, 2021 Tim That's way under what you want you'll be full throttle and struggling to get off the ground. With the 14x8x4 and 580kv your looking at around 48/52 amps full throttle. Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted October 25, 2021 Share Posted October 25, 2021 Thanks Paul. That's what I feared. OK, I'll find a larger prop! Quote Link to comment Share on other sites More sharing options...
Paul Johnson 4 Posted October 25, 2021 Share Posted October 25, 2021 (edited) 14x8x4 equates to a 15x10 two blade Prop conversions A bit bigger than you were going to use Edited October 25, 2021 by Paul Johnson 4 Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted October 25, 2021 Share Posted October 25, 2021 Thanks Paul. I'd not seen that web site. A bigger prop it is! Quote Link to comment Share on other sites More sharing options...
RICHARD WILLS Posted October 25, 2021 Author Share Posted October 25, 2021 The other tip worth thinking about with test flights is : If you have doubts or are really nervous about the first landing , then belly flop into wind . Surprisingly easy and with a two blade prop , unlikely to do any damage . The thinking behind it , could be that the next flight would be much calmer and the model fully checked for trim and loose items . On the same basis , I do a lot of my test flying with no paint and very little covering . Couldnt do that when flying glo powered! Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted October 25, 2021 Share Posted October 25, 2021 I do my first test flights with the model fully covered and painted. The second flight usually has less covering and paint, the third even less. Then at about the 10th flight they're nicely weathered (worn) in! 1 1 Quote Link to comment Share on other sites More sharing options...
Paul Johnson 4 Posted October 26, 2021 Share Posted October 26, 2021 8 hours ago, Ron Gray said: I do my first test flights with the model fully covered and painted. The second flight usually has less covering and paint, the third even less. Then at about the 10th flight they're nicely weathered (worn) in! So that's how you reduce an 80" model to a 60", now I understand 'scale' flying..... Quote Link to comment Share on other sites More sharing options...
Gordon McConnell Posted October 26, 2021 Share Posted October 26, 2021 On 24/10/2021 at 15:00, Tim Kearsley said: Well, a few things left to do, mostly cosmetic and rectifying minor cock-ups, but my P51B is 99% there. I've had some exhaust stacks 3D-printed by a clubmate and they are still to go on. The CG is a bit forward at around 90mm back so I'll have to see how it flies. I've not attempted any weathering or detailing yet - it could be tricky on a film-covered model. I just need to reduce the awful glossiness now...... Tim, your model is looking great in the Princess Elizabeth scheme. I am at the painting stage and I must say that this has been the most difficult and time consuming part of the build!! Hoping it is worth it in the end - pics to follow later. 1 Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted October 26, 2021 Share Posted October 26, 2021 Following on from my prop saga yesterday I tried out today the only other vaguely suitable 2-blade prop I have at the moment - a 16 X 10. That sounds a bit on the large side but a static power check reveals a max current draw of just under 60A and a power consumption of over 800W. Does this sound OK for a couple of test flights? I can always apply a curve to the throttle channel to limit the max power. Quote Link to comment Share on other sites More sharing options...
Graham Davies 3 Posted October 26, 2021 Share Posted October 26, 2021 Sounds OK to me Tim as long as you have enough headroom with your ESC. How are you for ground clearance? I tended to plough a furrow with my Warbirds until I got the hang of it! Be firm on the throttle stick, but don't whack it to the stop or you may find it a challenge to contain the left swing. ask me how I know... Graham Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted October 26, 2021 Share Posted October 26, 2021 Ground clearance isn't a problem Graham, so no furrows hopefully! Yes, the dreaded veer off to the left has caught me out too. I'm only intending to use the two-blader for a couple of flights to get all the trimming sorted out. A clubmate maidened his WR P51 a couple of weeks ago with the four-blade prop and ali spinner and nosed over on landing, bending the spinner back-plate. I'm just trying to avoid doing the same! Quote Link to comment Share on other sites More sharing options...
Graham Davies 3 Posted October 26, 2021 Share Posted October 26, 2021 You'll be fine Tim. My Yak is in regular use but I don't use the 3-blade prop as I usually belly land due to our rough patch. It helps with weathering on the underside! Quote Link to comment Share on other sites More sharing options...
Jonathan S Posted October 28, 2021 Share Posted October 28, 2021 Tim, Looking really good I must say. Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted October 28, 2021 Share Posted October 28, 2021 5 hours ago, Jonathan S said: Tim, Looking really good I must say. Thanks Jonathan, you're very kind. It looks reasonable from a distance! Up close it's less appealing. I think covering in film was a mistake and it has severely limited the scope to do some decent detailing and weathering. It's waiting for some suitable weather to have its maiden flight and in the air I'm sure it will look OK. The main thing is the building has been very enjoyable and a valuable learning experience. Mr. Wills is to be congratulated on producing a fine kit. 4 Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted October 28, 2021 Share Posted October 28, 2021 (edited) ! Edited October 28, 2021 by Ron Gray Removed!!!! Quote Link to comment Share on other sites More sharing options...
Jonathan S Posted October 29, 2021 Share Posted October 29, 2021 OK making slow and steady progress. I have shaped the front end. Drilled the dowel holes and test fitted the wings. Getting better at covering after doing the flaps ailerons and elevators. Only burnt myself once, reversing a servo. Thx Paul for the guide. ? So next challenge I could do with some help with is the wing fillets. The instructions and most people's builds seem to skip over this guess everybody knows how to do it or got bored of posting photos by then. Can anybody post some photos or help on how they go together ? I will post some photos soon. Thx Jon Quote Link to comment Share on other sites More sharing options...
Eric Robson Posted October 31, 2021 Share Posted October 31, 2021 Hi Jon, What I do is draw a line on the the ply fillet base where it protrudes from the fuselage, the straight edge should line up with the inside of the fuselage, lay some plastic film on the fuselage to stop the glue sticking the wings to the fuselage fit the wings to the fuselage with a gap to allow the the ply base for the fillets to slide in, glue the fillets up to the mark and slide in the gap tighten the wing onto the fuselage and allow it to dry, lay the triangle balsa on the joint and note the curve, where it starts to increase mark the point with a pencil then from there make a series of cuts at the back of the triangle not enough to go through form it round the wing curve using extra cuts till it sits on the ply base glue and pin it and when dry shape it, to get the concave curve, sand paper wrapped around dowels of various sizes will get the shape you need then use a light weight filler to finish off. 1 Quote Link to comment Share on other sites More sharing options...
Trevor Posted October 31, 2021 Share Posted October 31, 2021 Jon, I didn’t respond initially for fear of generating confusion because I took a different approach. There are some pics halfway down this page: http://www.bartonhewsons.uk/home/modelflying/scale/mustangprojectda.html By coincidence, I just used the balsa fairings supplied in the kit to make hinge blocks on my current build - waste not, want not! 1 Quote Link to comment Share on other sites More sharing options...
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