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Ed Kershaw

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Everything posted by Ed Kershaw

  1. Ed Kershaw
    Many thanks for all your thoughts. Fascinating article, Gonzo. Interestingly, I have now actually bought both a SS25BBD and a SS30BBD. Having bought the 30, I thought it was a bit heavier than I wanted it to be, so I bought the 25 (on no better information than it was a smaller engine so it might be lighter - info on Enya engines being very sparse and hard to find!). The odd thing is, the 25 has the same external dimensions as the 30, and its also heavier! So the 30 is larger bore and stroke, lighter version of the 25.
  2. Ed Kershaw
    Evening all, I was just wondering if anyone has any experience of Eyna diesels. I've just ordered a 30BB diesel from the Enya website on a bit of a flyer, for CL stunt, with not much in the way of specs given on the website. I am hoping it will pull a 35 class stunt model (Magician) round pretty well. Any views or experience gratefully received - props/rpm/weight etc?
  3. Ed Kershaw
    Many thanks i12fly and Stephen. I think it's going to be the Flair kit. It seems to be quite a light build and, judging by the customer photos on the Flair site, someone seems to have achieved a more representative shape to the mid wing centre section, so that should be achievable without too much trouble. I'll post some news/pics when I get going.
  4. Ed Kershaw
    Hi All, Having decided my next project is to be the popular Fokker dr1, not surprisingly there seems to be a lot of choice. I was wondering if anyone has any experience to bear? Choices seem to be: 1. Balsa USA 1/4 scale - I can't find much detailed info on this. I have found one build thread on rcscalebuilder, but the builder modified the kit extensively so I could not get a good appreciation of the original intention. 2. Flair 1/4 scale. Seems to be quite a nice straightforward build, but seems to miss some essential scale features, such as the cut out in the mid wing around the cockpit. Whilst I am not looking for detailed scale, this seems quite a radical and possibly unnecessary departure from the original outline. 3. Zirolli 1/4.4 scale. Looks quite a straightforward build but I have read that it can come out very heavy leading to fast (and unscale like) flight. Also, the nose looks long and the cowl doesn't look that scale - perhaps I'm mistaken. 4. Geln Torrance 1/4 scale. Seems to be a very detailed scale model - more detailed than I really want to take on for this project. My criteria are: Reasonably scale looks - I.e. General outline must be reasonably convincing. Needs to be light. I ran out of enthusiasm for heavy models years ago. Any views or other information most welcome. Many thanks. Ed
  5. Ed Kershaw
    Does anyone know if you can get fine pitch pinking scissors/shears, say, 15 to 20 teeth per inch?
  6. Ed Kershaw
    1  Mode 1 2  Oxfordshire 3  Oxfordshire 4  Self taught on MacGregor Digimax 2 - hence mode 1 addict
  7. Ed Kershaw
    I put a bit of work into comparing motors in an effort to assess 'power to weight' and efficiency, including building a dynomometer (the results were published on this site some time ago).  I have several Axis ranging from 400 to 90 size, a few real cheapies and several Scorpions.   My conclusions were that, from a mechanical point of view, Axis are superior to anything else I've seen.  By this I mean general robustness (e.g. twin races at the 'business' end of all motors), build quality, fit and finish of components, quality of accessories and robustness of mounting system.  However, electromagnetically I think they are possibly a bit old fashioned now and lag behind others.   Take the 4120/18, for example.  Weight 320g; Dia 49.5mm; 515kV; Cost £94.50.  Max continuous output? - Axi do not state, but they do state max BURST current 55A for 60S, so I assume the max CONT current is probably around their stated max efficient current of 40A.  It may be safe to run continuously at 45A - probably not much more.  At 6S, this give max cont power of 945W.  Max power to weight -  2953W/kg.   I had a stator burn out on a 2 month old 4130/20.  Axi repaired it free of charge.   Compare this with the Scorpion 4020/12.  Weight 304g; Dia 49mm; 542kV; Cost £57.50.  Max CONT current 80A; Max CONT power 1500W.  Max power to weight 4934W/kg.   So, if, like me, you like building 'light', you can do better than Axi and spend less money too.   When I compared the efficiencies of Axi and Scorpion on the dyno, there was nothing to choose between the two.   With a Scorpion motor you also get the 2 year burn-out and defect guarantee, plus a 50% crash replacement offer - so they're obviously pretty confident.  It's Scorpion every time for me these days for motors (although their ESCs still seem a bit 'agricultural').
  8. Ed Kershaw
    That's a technical looking job, Tim.  Very state of the art!  I had a similar idea for my GP Stearman, but doing it the "old fashioned" way with a lipo 10s setup.  The CG did come out right on the nail, though, with no weight added (the kit calls for 18oz inside a plywood box on top of the OS120).  AUW a shade under 14 lbs.  I do like light aeroplanes!  I think there's a good chance it can work on a tiggy because there's so much room under the bonnet, and an equivalent outrunner is so small.  This is a modified Scorpion 4035-600 heli motor - rewound for 195kV.  It's only 435g and delivers over 2kW.  
  9. Ed Kershaw
    Scorpion 2kW Axi 77A 10s
  10. Ed Kershaw
    Many thanks again to all for the suggestions and comments.  Is 14/15 lbs a lot to expect from the Flair TM?  I was hoping that would be achievable with our Hutson version.  Light aeroplane do fly so much better.  I remember I did once see the Flair scale sprung u/c assy for one.  Lovely piece of hardware, but I remember thinking it seemed quite heavy.  Maybe I'll get a shock when ours gets assembled and weighed.   Well, the fuz and flying surfaces are coming along well on our Hutson version and it's time to bolt some metalwork in the front.  We made the decision this weekend to go for the Laser 180, so that'll be on order tomorrow.   The build has been quite interesting so far, with various kit related anomalies and frustrations, but I'll write something about that in another section.
  11. Ed Kershaw
    I've read build reviews where the builder says he used ammonia to soften balsa to bend it into tight radii.  Does anyone know how this is done and where to get the ammonia from?   Many thanks. Ed
  12. Ed Kershaw
    There is one other possibility.  Sometimes rxs don't like what they see from (poorly filtered) switching becs.  This one cost me a model.   Ever since then I have used the UBec from Gordon Tarling, which, although a bit pricey, seems steady as a rock.    
  13. Ed Kershaw

    Ed Kershaw posted a gallery image in Member Albums

  14. Ed Kershaw
    Many thanks to all for the comments.  An update on where I've got to with this:   I spoke to Geoff at Laser engines who informed me that they actually make a Laser 180 that is pretty much ideal for 1/4 scale Moths - long stroke, torquey, not lightly built at 1200g, and reliable.  He advised strongly against petrol conversions to Lasers.  They have never tried it and don't intend to.  I asked why the 180 is not advertised on their website and was told that as they sell all they can make, they don't need to advertise it!   The Saito FG36 petrol is the other option (thanks for the steer, Bruce).  It is quite heavy, all up (1700g+), and quite expensive - more than twice the price of the Laser.  There are various forum discussions about problems with lubrication on these - I don't know if this is sorted out yet.  Of the two, this seems the higher risk option, although less smokey and cleaner (probably) if all goes well.   I think the Laser 180 is the way to go....   Arte and Marty, your electric set-up sounds impressive.  That will deliver about 2kW at the prop - about 2.7hp.  I should imagine you'll be able to stand your Moth on its tail at 130 W/lb.    
  15. Ed Kershaw
    Peter, a photo showing the problem would be helpful.   If I understand you correctly, you are proposing to pull the wing roots together with a toggle clamp rather than screw them to the sides of the upper cabin walls.  This would put the cabin under compression.  Is that OK?  If it is, why not use a turnbuckle?  Then your only difficulty is making a LH thread, which only involves a small investment of tools from Model Fixings.   Or have I misunderstood things?   Ed
  16. Ed Kershaw
    Interesting idea - a petrol Laser.   I'll see if I can contact Neil Tidey and see what he thinks and post back.
  17. Ed Kershaw
    No reason at all.  That was really the point of the original question - what other options could I be considering?   So long as it meets the critiera, i.e. quality, reliability and sounds more like an aeroplane than a chainsaw, any options are good.   Can you let me know what the petrol options are, please?  I guess it would need to be 4 stroke.   Many thanks.
  18. Ed Kershaw
    Many thanks for the comments, gents.   It really does seem that the choice is OS120 or Laser150.  That's it.   Personally, I think that, of the two, the Laser is the way to go as it is lighter, more powerful and, in my opinion, sounds better.   It seems that Mick Reeves ONLY uses Lasers, according to his website.   I have to say,  I am surprised that there are no other serious contenders to power 1/4 scale bipes.   I'll get the shovel out....
  19. Ed Kershaw
    In trying to choose an engine for this project, my criteria are, (probably in priority order):   1.  Sufficient power 2.  Reliability and engine quality 3.  Noise quality (i.e. long stroke/slow turning 4 stroke??)   Also, I'm prepared to shovel a bit of money at it (unusually for me!)   It seems to me that the OS IL300 is simply to big and heavy.  Therefore, it is a straight choice between the Laser150 and OS120.  (Or low kV electric - possibly not as daft as it sounds as you only get the prop noise and not the garden strimmer/chainsaw engine effect).   Are there any other sensible choices I'm overlooking?   Many thanks for any responses.
  20. Ed Kershaw
  21. Ed Kershaw

    Middle Phase nose

    Ed Kershaw posted a gallery image in Member Albums

    Middle Phase nose
  22. Ed Kershaw
    Hi John, I covered my aileron Middle Phase with solarfilm in 1987 and, other than some  "battle damage" it still looks and flies good.   I find solarfilm is great for doing complex shapes, like a pointy nose, but you have to treat it like a "shrink wrap" rather than a fabric cover.  I just had a look at my middle phase and saw that I did the fuselage in two bits per side, the rear half up to the front wing band dowel, then a second bit from there forward.  To do something like the nose of a middle phase, you need to cut a much bigger piece of film than you would have thought, perhaps 4-5" bigger al around the front of the nose section.  Then, having tacked it on quite firmly at the rear join, you grab hold of the excess film at the front with one hand and, whilst heating it with the other, pull it around the shape.  You have to pull quite hard sometimes, but you'll find it will just wrap round nicely.  I use a heat gun for that bit, but the guys at solarfilm recommend using an iron as they say you can overheat it with a gun.  I find I overheat my fingers first!  You'll need to get someone to hang on to the back of the fuselage whilst you do this.   You do have to deal with the dust by vacuming both your build area and the model before you start covering.  But this must apply to all films, surely?   If I can work out how, I'll put a photo up.
  23. Ed Kershaw
    For what it's worth, I do this sometimes too and prefer to use a really thin coat of laminating epoxy (I get it from a boat chandellery).  I find the difficulty with copydex is that a) it curls the skin backwards and makes it difficult to position, then b) to make matters worse, you only get one go at it as you cannot reposition with copydex.  Plus, when you come to sand the edges you get little balls of rubber where you want to glue the LE and TE on.  Maybe I just don't have the correct knack.   One of the nice things about the epoxy method, other than the ability to reposition, is that you can also laminate a thin layer of glass into the skin/core joint to make a really strong wing - useful for high aspect ratio long thin wings.  I've got an old German F5B model that used this method.  The wings take massive G loads and seem virtually  indistructable.   In his excellent book "Radio Control Foam Modelling", David Thomas demonstrates several methods, but he seems to prefer using the Gudy O film, as Matt suggests.
  24. Ed Kershaw
    And thanks for all the responses, gents.  I'll persevere (probably until something gets broken) - but that's what it's all about .
  25. Ed Kershaw
    I fly an Extreme Flight Extra 330 58" mostly at the moment.  It's completely standard spec with the airboss 540 motor and 4000mAh 5s lipos from Maxpoly.  14x7 prop and Hitech digi servos - it's got plenty of grunt. The controls are nice and tight (i.e. no slop).  CG is as recommended.  To get this further back I'd have to move the flight pack behind the main spar - which would be a bit of a problem - or stick a chunk of lead in the tail end.  The other recommended prop is a 15x8 for that, but it seems to go well on the 14x7 and pulls about 60A static, so I've not tried the bigger prop yet.   Alternatively, I could use a smaller Hyperion Sukhoi - about 45" - which is quite old and a bit tatty now - so might be better for experimenting with or a LN models Mamba - both of which will climb vertically out of your hand.  The Mamba has a long moment arm and is very agile.   I have to agree with you to a large extent, Terry.  Personally, I don't think there's much about aeromodelling that makes for a good spectator sport.  I don't tend to go to shows at all.  Having said that, a really skillful bit of C/L combat flying can be quite exciting to watch (although I'm pretty sure my wife would disagree!).
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