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Chris Bott - Moderator

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Everything posted by Chris Bott - Moderator

  1. Chris Bott - Moderator
    Oh no - I ordered that ESC specifically for 8S, thinking that an 8S lipo spec would be more than OK with 8S A123's    - Oh well, we'll see when it gets here...  I have a couple of super simples coming from Hong Kong too.
  2. Chris Bott - Moderator
    Danny - great minds think alike (and fools never... etc)  I ordered one of these last night, http://www.allelectricrc.co.uk/suppo-su70a-opto-esc-4-8s-1282-p.asp Looks like my Fury is going to be dearer than yours! Just hope this is nothing like as big as the one they showed us at Weston. It has apparently been dispatched, so I'll let you know how it is soon.
  3. Chris Bott - Moderator
    Look what I got for fathers day... I love my family (Beyond the Tiger Moth)
  4. Chris Bott - Moderator

    Chris Bott - Moderator posted a gallery image in Member Albums

  5. Chris Bott - Moderator
    Timbo - that 8S test looks very promising If thats a 400Kv motor on a 13x6 prop, isn't that about right for 8S? The motor we have been swearing by on 6S A123 seems to have been split into 2 types 600kV Motor and 700kV Motor although when we bought ours they were all rated at 670kV allelectric motor looks suspiciously similar except its silver, and they are on special offer. As we use them on 6S with 13x6.5 and 14x7 props, won't you have to go to quite a small (too small) prop to use this kV on 8S? Also, your batteries do show a steady drop off of volts, metal can ones dont do this.... 
  6. Chris Bott - Moderator
    Lipodapter  does apparently work well. Note though that you do need to balance A123's too. Not every charge. I do it at home after a flying session.
  7. Chris Bott - Moderator
    Timbo, I'll hold off sending these cells until you decide with Andy. If you are changing your motor in the Watty, I'd go for a 670KV tower pro or similar and use 6 A123's. We are pushing these to 1Kw at full throttle, but using that sparingly as you know. (I don't think you'll look back) I'm beginning to think in mWh rather than mAh.  Can you tell me if this all makes sense? 4S 4000mAh LiPo will give you 40A for 1/10 hour (in theory) 6 minutes. With Lipos you'll stay away from using all that for fear for the batteries health.  I'm guessing this would be at say 3.4V/cell? = 13.6V This giving 14x40= 540W  for 6 mins. 6SA123 2300  giving 540W would be at around 3V/cell = 18V x 30A. The 2300 would last 4.6 mins. This is getting pretty close. And you get full power right throughout the flight. Thinking in mWh  4S 4000mAh cells are 13.6 x 4000 =  5440mWh (except you can't use it all) 6S A123 2300 are 18x2300 = 41400 (that you can use all of) Just comparing mWh makes for an easy comparison.. 
  8. Chris Bott - Moderator
    Many thanks David. Its a difficult one at that price.  Probably worth going for. I can restore the rest of the plane into almost good as new. But the fus will always look battered and mended.  Especially as I have a big piece missing !
  9. Chris Bott - Moderator
    Yep no problem. I have a couple of 3S's that have been swapped between long sticks of 3 and side by side configs 3 times. So they are pretty tolerant to that too. I could never see me making this offer with LiPo's can you
  10. Chris Bott - Moderator
    That's fine, if you can't do it what chance have the rest of us got? They come tagged together as 10S. I always try to cut the tags in half and solder to those. I've never had a problem with the welds except from my clumsiness.  I want to keep a 6S tagged intact from the 10. So I'll see if I can get a 4S as well, or maybe 2 2S's. I have soldered to bare cells OK. Just takes a huge Iron, and as quick as poss. The can end (+ve polarity by the way) doesn't half soak the heat away!
  11. Chris Bott - Moderator
    No probs, trust you won't keep 'em too long . And of course, they will only be bare cells. It does depend on the ebay seller sending them to me etc etc - so I cant give you any timescales yet. You probably know that when they have stock, they are available from our freinds at Hobby City. Search for  26650A I've had one of those to add to an existing 6S to make it 7. That is working fine so I'm pretty sure they are genuine. IF you ever beleive in them, you need a battery like ebay item 170224559108. But note many of these are US sellers, we avoid those because of postage and duty etc etc. Of course BRC do a 4S pack made up for £60 ! I am told that Alan Fry at Importechnik is making up packs with balance leads for £11 a cell. But I havent checked that. Or whether they are "genuine". 
  12. Chris Bott - Moderator
    Timbo I would suggest that those batteries are LiFe's but they are no A123's. The grey line is volts isn't it? This just sags right off from 5.5mins onwards. A123's just dont do this. They generally either give full power or are empty. My guess is that A123 (manufacturer) are using their nano particle technology to create huge surface areas for the chemistry to take place. Other manufacturers may be trying to catch up, using the same chemistry LiFe (Lithium Iron) but in a more conventional manufacturing technique. I have another 10 cells in the post somewhere (another De-Walt battery) assuming that arrives, I could send you 4 to try. If you would send them back after testing. I dont have as much use for them temprorarily now the DH88 is kitted again . You'd only have 2300 mAh, but you'd have all of it! And I recon they wouldn't dip much under 12V in your setup. I understand if you'd rather get your own, but I'd urge you to try the real thing
  13. Chris Bott - Moderator
    Its getting longer! (ooer missus) But it seems that some kind soul took some pieces to throw away for me.
  14. Chris Bott - Moderator
    Wow - many thanks
  15. Chris Bott - Moderator
    She looks a real corker in the air and on the ground. But those pointy wingtips bite! First flight was a nightmare. So I got a heat gun and my hob nail boots on the wing tip sections and added lots of washout.  Of course that meant thrustlines and trim were out. Flight 2 proved very stable at low speeds, but it went well nose up at full power. So thrustlines were changed. Flight 3 on Sunday was nerve wracking but I enjoyed it. Flight 4 I was getting confident. (Often my downfall). I see it as a challenge now. As long as I don't spend (waste) much money and then fail. Repairs could go in fits and spurts, do a bit then leave it a while.. Fus is firming up nicely. Looks like theres a big bit missing though, I thought we'd retreived everything. Some part of the nose will have to be new... Anyone know the best way to ask Ripmax if they can do a new Fus as a spare?  I really dont have good experiences of local model shops ordering me stuff.
  16. Chris Bott - Moderator
    Repairing splits in the thin plastic Nasty tear.... Sellotape over.. Skinning cloth pieces Cyano inside with pink Zap Hey presto - bggr some paint came off. of course earlier ones were much better when I didnt take piccys. So, is it worth continuing with this? Its not costing much..
  17. Chris Bott - Moderator
    Right on to the rebuild decision. Damage report:- Plasic over ply & carbon skeleton fuselage crushed, splintered and split back past wing LE. Internal skeleton ply formers in pieces, carbon tubes in splinters. Wing seat ply broken and broken out. Ply former for wing dowels broken and out. Ply cross piece for wing bolts broken out and bent. Servo tray, broken out. Canopy, Cockpit, and whole tail end - fine.Fibreglass Nacelles, both crushed at front, both firewalles broken, motor mounts bent and in bits. Cowls OK except mounting holes torn. Motors, ESC's, batteries & undercarriage fine. (1 battery needs a rebuild but all cells are OK)Wings. Cenre section crushed where nacelle mounts on dowells. Nacelle mount screw has pulled through wing. One Wing tip piece has root rib mising and some of bottom skin ripped out. I have done a few repair tests on the plstic of the fus. Where I could pull the splits together, I've taped over with sellotape outside, getting the join spot on. Then applied thin skinning cloth with thin Zap on the inside. This technique has already nearly restored the fus skin, right up to the front of the wing. I will carry on and see how far forward I can get with it still looking OK.
  18. Chris Bott - Moderator
    Heres some pics This last one is after the split repairs
  19. Chris Bott - Moderator
    I beleive that it flicked on opening the throttle just beforehand. The thought was going through my head that I'd lost a motor. It recovered with power off. So the most likely scenario is that while I was deciding what to do about that, and looking round for a deadstick landing, it got too slow. I did decide to try throttling up again to see if it flicked again. I even think I did start to throttle up again, but I guess by then it was too late. A dab of down elevator instead and all might be in one piece. Testing at home:- I'd used 770mAh of 2300. Eagle tree, from the motor that may not have started when it flicked, shows good volts, lowest during takeoff and the loop and higher again round the last circuit and at the end.  Both batteries are OK but battered. Both motors run fine, both ESC's work. (Could one have overheated? not at the currents I was pulling I doubt). I'll have some damage photos later. I wish I'd taken some on the ground straight after.
  20. Chris Bott - Moderator
    Morning. Just been and checked, and it did really happen. My Ripmax DH88 Comet is in lots of bits. Flew 3rd and 4th flights with Danny and his Fury yesterday morning. I was getting used to, and really enjoying the DH88 when disaster struck. Theres a video below of the last 90 seconds. I have at least three theories as to what happened. Listen to the engine note just before the first flick/tipstall.
  21. Chris Bott - Moderator

    Chris Bott - Moderator posted a gallery image in Member Albums

  22. Chris Bott - Moderator

    Chris Bott - Moderator posted a gallery image in Member Albums

  23. Chris Bott - Moderator

    Chris Bott - Moderator posted a gallery image in Member Albums

  24. Chris Bott - Moderator

    Chris Bott - Moderator posted a gallery image in Member Albums

  25. Chris Bott - Moderator

    Chris Bott - Moderator posted a gallery image in Member Albums

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