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Piers Bowlan

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  1. The Aerocobra has aerodynamically balanced control surfaces to reduce control loads. The p39 is unusual in that they extend the full width of the elevators whereas it is generally more usual to involve part of the control surface, notably the top section of the rudder of aircraft with unpowered controls (generally light aircraft and warbirds). An alternative solution to reduce aerodynamic control loads is a balance tab. Incidentally, an ‘anti-servo tab’ has the opposite effect and fitted to an all flying tailplane to increase loads. Aircraft with powered controls don’t usually have aerodynamically balanced controls. As Craig said earlier, frise ailerons produce drag on the down-going aileron to help counteract adverse yaw. Awesome model build, following with interest
  2. Presumably it is obvious that that the two halves are misaligned at the root Andy? If the two wing panels are aligned at the root but there is twist in one of the wing halves at the tip (warped) then obviously there is not a lot you can do about that, apart from build another wing, like you say. It could also be worth checking the lateral balance point of the wing, for if one wings is significantly heavier than the other (not uncommon with epoxy/glass wings) this will also affect the lateral trim. In addition! A twist in the fuselage can cause roll (further effect of yaw is roll) requiring aileron trim to correct. I just thought I would add my two penny worth to be clear on what is causing your problem before you saw your lovely wing in half! If you can’t live with it the way it is, then there is nothing for it but to saw away, through the spar and all. (if there is one). I have made several foam wings over the years and usually I make a vertical slot in the wing roots and then cut a full-depth ply web (1mm thick) as a dihedral brace, which I securely epoxy into the foam. A layer of glass cloth and epoxy across the joint should render the wing pretty indestructible. I hope you get it sorted Andy and good luck.
  3. Thank you for the explanation idd, I understand now (I think ?) I must confess, I didn’t look at the price of the smaller battery when I bought my Leaf and I agree, 95% of the time you don’t need a humungusly large battery (Tesla drivers please note). I think there is a market for a basic no-frills EV with a 100mile range. For instance, you don’t need a Bose sound system, adaptive cruise control/lane keeping etc. The Chinese build them for the Chinese market but not for export, which is a pity because in China they are silly cheap and look like…. cars, not a design schools student’s nightmare (Twizy!).
  4. Great looking model Graham. Respect! Sorry to hear about your unfortunate rapid arrival due to control issues. As it is the second time this has happened it is likely a common cause? Did you use the same motor ESC in both models or if a separate RX battery, the same battery? Whether a complete loss of control or slow servos with glitching, both could point to a problem with the power supply with Rx and servos. Two duff Rx? Probably not very likely. Just my 2p worth.
  5. I did consider a used Leaf as I thought I would just use it very locally so range wouldn’t really be an issue and it was better than cycling in the rain! I am glad we got the new one as it turned out. We use it as our primary car and did 12k miles the first year. I believe battery dedradaton isn’t such the big issue some people think. I bought a ‘wizzy’ Audi TT back in the day but after 12 years and 95k miles it was quite seditory, so even ICE engines lose their sparkle . My Leaf is 217ps and does 0-60 in 6.9sec so if it loses 20% of that in 10 years it will still have 173ps (not too shabby!). OK, the range will reduce to 192m from 240m (144m from 180m, typical winter driving). The electric drive train including the battery is guaranteed 8years and 100,000 miles by Nissan against any defect including dropping 20% in battery capacity/performance.
  6. If the c of g is too far forward it will fly badly, too far back and it will fly once. Any idea of what make of model it is, if it is ARTF or who designed it, if built from a plan? 25% of mean average chord as a starting point if you can’t find a published figure for the model. Good luck with the maiden Craig .
  7. I appreciate that GG but in fairness I did say ‘in a couple of decades’ when there is infrastructure everywhere to cater for EVs and a large second hand car market. Battery costs will have inevitably fallen too (solid state and aluminium/air batteries?). Even today new EV cars are available in China for £10K. Inevitably with anything new it is the luxury market which is catered for initially. Prices will fall in real terms when they become mainstream. A new Leaf is £28k if you are not fussed about leather seats You could buy a used one until recently for £7000 with a 30kWh battery, before the second hand car market went mad. A basic new Octavia SE is over £24,000 by comparison, incidentally. Yes, less than a Leaf. I am on a pension too by the way GG. I meet many people driving around in luxury SUV who could have the means to go EV but are wedded to their ICE engine because that is what they have always had.
  8. Interesting post, particularly ‘buy the smallest battery you can with the fastest charge capability’ the logic of that is a bit lost on me ? I bought a Leaf a year ago - I will never go back to ICE. But given the choice between the 40kWh and the 62kWh Leaf battery it was a no brainer - I got the bigger battery which can provide a total range of 240miles or, - on a frosty morning with front and back heated windows, heated seats on high, a/c on etc. more like 180 miles. Annual mileage of 7500miles (22miles a day) is the national average so for most people a 180 mile round trip range (worst case) is adequate for the vast majority of journeys. ICE drivers are oft heard to say ‘but I can refuel my car at the garage in five minutes’ while I say, I can refuel my car at home in five seconds ( 5 seconds to plug it in and is ‘refuelled’ whilst I sleep ) . People are very conservative and resistant to change. In a couple of decades I think most people will be convinced and think it odd that we actually drove around in ICE vehicles ‘back in the day’
  9. Buy a roll of cellophane as nothing sticks to that. It is available on eBay, it’s used by florists, in the food industry and GRP manufacture. Some art and decent craft shops sell it sometimes too. Cling film a a waste of time, as you discovered.
  10. It is also interesting that Nigel says that he has had to add weight to the tail to achieve the published C of G (75mm from LE). Quite a few references to this online but not everyone has this problem, indicating some inconsistency in the foam density used during manufacture. Most 3S 2200mAh LiPos don’t differ vastly in weight. In any event, many people fly with a c of g at 65mm with no ill effects, by all accounts. if you do find the fuselage very flexible Nigel it is easy enough to reinforce it with thin carbon strips, as I have done with several of my foam models over the years. Using a steel ruler as a straight edge, carefully cut a slot down the belly of the model, no deeper than 10 mm. Push the strip (8mm x .5mm) into the slot so that it is buried. Now run thin cyano along the slot - job done. If there is excess lateral movement another strip can be inserted into ONE side of the fuselarge. Just ensure the fuselage is completely straight before applying the cyano! Just to confirm the strip is half a millimetre thick, not 5mm!) Good luck
  11. I am not familiar with this model but reading the instructions it says ‘it has an innovative internal structure adding strength where needed and locking the components together’, to paraphrase. If this internal structure (carbon tubes?) is not properly bonded to the foam (insufficient glue) and/or the model has had a crash, it is likely any stiffness that should be added by the reinforcement will be lost. If you grip the tail boom and try and bend it in pitch it should be quite rigid despite being made from EPO. If it flexes more than a couple of mm the inflight loads will be sufficient to cause the tail plane to adopt a negative A of A and a strong positive pitching moment. = loops! Hence you find a lot of nose down trim is required. Just a theory.
  12. Thank you for subsidising my use of the road Martin! Actually you are only subsidising about a third, as two thirds of the revenue raised goes into general taxation (£35B revenues vs £11B spent on the roads). Clearly the exchequer will have to make up the shortfall in revenue as more and more people go over to the ‘dark side’ (EVs) and there is certainly a lot of talk about it. However at the moment it is just talk and speculation - nothing is decided. A road pricing strategy using GPS and taking into account not only vehicle weight but also geographical area (rural/urban/inner city) will eventually evolve. However the technology/infrastructure/software will have to be developed and installed in all vehicles. More significantly, acre’s of legislation will be required concerning confidentiality and data protection. How long will all this take, considering the consultation documents, inquiries and parliamentary debate involved? Meanwhile, I am saving £2000+ pa in fuel and road tax
  13. Rather that using PVA could you not use epoxy which shouldn’t get lighter as it dries? Oh, and welcome to the forum Barry, from me .
  14. ‘Saving the planet’ wasn’t the criteria for me choosing to go electric. I don’t have brand loyalty, I chose the Leaf on its merits. When it’s PCP agreement ends in another three years time I may chose another brand, it depends on what is available compared to what I have now. I am pretty certain it will be electric though.
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