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Frank Skilbeck

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Everything posted by Frank Skilbeck

  1. Frank Skilbeck

    Frank Skilbeck posted a gallery image in Member Albums

  2. Frank Skilbeck

    Frank Skilbeck posted a gallery image in Member Albums

  3. Frank Skilbeck

    Frank Skilbeck posted a gallery image in Member Albums

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    Frank Skilbeck posted a gallery image in Member Albums

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    Frank Skilbeck posted a gallery image in Member Albums

  6. Frank Skilbeck
    Watch some of the higher capacity AA cells, I have a pack of 2400 mah AA cells (4.8v) and the voltage drops right off if I try to pull more than 0.5amps from it. If I cycle it a few times it seems to improve but then will revert to what it was. Note these are not the newer instant type cells. The GP NimH cells (AA & Sub C) seem very good in this respect.  
  7. Frank Skilbeck
    Not really it would depend on the diameter of the fan, if its only 50-60 mm then it will be a smaller diameter than the prop, I have a couple of small EDF's around 50mm using 4,000 kv motors and they pull around 20 amps. a 1350 mah battery is very small for this application hence it's getting very hot and probably cutting out after a min due to the LVC cutting in. Just for interest I ran a 3200 kv motor with a 4.5 x 3 GWS prop in the Drive Calc simulator and on a 3s set up it predicted it would pull 20 amps, so I would say that it's the battery which can't deliver the amps. Not sure why your ESC failed though. Note an APC 4.5 x 4.1 prop increases the current draw to 25 amps, so it would be good if you knew what the prop is as a small differnce in size can give a big difference in the amps drawn.
  8. Frank Skilbeck
    what about this one http://www.4-max.co.uk/tn-lightning.htm as mentioned in RCME August issue Fly Electric column.
  9. Frank Skilbeck
    or aren't, in fact.... That's surprising I thought there would be a good demand for these. Don't forget you might need to add some nose weight to your twin star, I'm using a 3250 mah 3S and needed some extra nose weight. 
  10. Frank Skilbeck
    The reason the 400's struggle on a 3s lipo is that the volts are typically higher than a good old 6 or even 8 cell Nicad, so the 400 will spin a lot faster, the power drawn on a given prop is roughly the square of the speed, i.e. twice the speed 4 x the power, so if you doubled the voltage then the amps would also double. If you put a smaller prop on then the motor will still spin faster but need less power to spin the prop at this speed so the amps will come down. Beware of reducing the WOT setting in the travel adjust on the Tx, some ESC's autosense where full throttle is so dialing it down this way might result in the ESC setting 100% when throttle is at 40%. You'd be far better just throttling back when in flight, you then have the option of overpower for brief durations if required. I've got a twinstar running on the original 400's with a 3s lipo and use full power for take off on the UC I've fitted and then throttle back. The motors may burn out eventually and then I'll replace them with some the new brushed lipo specific 400's that Puffin Models are stocking.  One thing to watch if you are running the Grunther push on props is that the extra power can cause them to come loose and fly off , I had to put some proper prop adaptors on mine. Next I'm off to try my Twin Jet on 3s on it's 480 motors, should be fun. 
  11. Frank Skilbeck
    Nice sets, but why have the display under the neck strap which makes it more difficult to read. Also it looks like the neck strap is positioned for a long 35 aerial to balance not the short 2.4 aerial. The Spektrum DX6i addressed this by putting the neck strap clip below the on off switch surely this wouldn't have been too difficult on these top end sets. Maybe the futaba still has the 35 aerial so you can get the set to balance
  12. Frank Skilbeck
    OK I wasn't sure why you were disconnecting the red wire if you though the ESC didn't have a BEC. I agree it's probably best to use a separate Rx battery  than a regular BEC, the new ESC I've just got uses a switching BEC which can drive a full compliment of servo's.
  13. Frank Skilbeck
    My turn please
  14. Frank Skilbeck
    Coming out red hot is probably part of the answer. I haven't measured how many cycles i get out of my cells, but I put a 1400 mah 3s in a plane which normally used a 1800 mah 3s (both 12c I think) and the 1400mah was ruined pretty quick. I'm running some 1500 mah cells (3s) in my EDF but it's only about 200w and the cells come out warm not hot, I have not noticed any significant deterioration to date but I'm probably only running them at 12C or less. 
  15. Frank Skilbeck
    Timbo, I've just got a Turnigy 60A ESC with a built in SBEC rated for 3A continuous, 5A peek. I think Turnigy and Tower Pro are just rebadged versions of the same. If i understand Dave correctly he might have an ESC with BEC and has disconnected this to use a separate battery. The problem with then using the programming card is that the BEC probably provides the power to the control electonics in the ESC and programming card, with an OPTO ESC the power for the control electronics probably comes from the Rx battery. So if the red wire is disconnected then there is no power from the BEC to the programming card. Dave I didn't understand your comment about the other servos and Rx when you were using the programming card, to program my ESC I have to unplug it from the Rx and plug it into the programming card.
  16. Frank Skilbeck
    A 3200 kv motor is a very high rpm motor for use with a prop unless used with a gearbox. What size prop was supplied.
  17. Frank Skilbeck
    Dave, just a thought your ESC has a BEC and will use the BEC to power the programming card when you connect it to the ESC, if you've disconnected the red wire then it won't  power the programming card. I have a Turnigy one which I think is the same as the Tower pro type and it does have provision a separate power supply if you are using an Opto ESC. But maybe to program the ESC with BEC the ESC has to power the programming card, have you tried reconnecting the red wire when you are using the programming card. Note as Timbo says though the lipo setting won't affect the max power sent to the motor just the low voltage cut off  point.
  18. Frank Skilbeck
    To get 700 watts from a 4s battery you will be pulling over 47 amps, thats about 13c on your existing battery so shouldn't be a problem. But you would only get 4.6 mins at wide open throttle so allowing for flying at less than full throttle you would need to set your timer for less than 7 mins. I would think 2 x 3s batteries you mention above would be a better way to go with this plane, 700 watts on a 6s is going to be around 32 amps which is kinder on your batteries and gives a decent flight time, well over 10 mins.  I've got one of these https://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=2099&Product_Name=TR_42-50A_700kv_Brushless_Outrunner_/_720W Gives 8900 rpm on a 13 x 6 at 36 amps on a 4s battery, about 550 watts, you could probably put a slightly larger prop on it and draw a bit more current.
  19. Frank Skilbeck
    I ran a 370kv motor through drive calc using a 16 x 10 prop and it gave these results 4S - 23A, 4700 rpm, 2029g static thrust 6S - 45A, 6550 rpm, 3949g static thrust  So looks like you need a 6S battery (or 2 x 3S in series) and your ESC would be fine. Note I substiuted your  motor for a similar one as the Thumper motor was not in the data base. If you went to 8S you might have to prop down, say 16 x 8
  20. Frank Skilbeck
    I think the fleet plugs were pretty specific to fleet, I can't remember anybody else using them. The batteries in the TX are not on a plug but are soldered directly in, well they are on the two sets I've got. Can't you reuse the leads off your existing RX battery. 
  21. Frank Skilbeck
    The "batteries" or ultra capacitors you describe might not be 30 years away http://www.technologyreview.com/Devices/wtr_16326,303,p1.html?a=f
  22. Frank Skilbeck
    If you are just a relative beginner the small park flyer low wing types might not be all that great as orientation can be a problem and they get small very quickly, probably best for after you've had one low wing plane under belt, and then I'd recommend one of the Alfa warbirds. But for now you might want to consider something like a Multiplex Minimag http://www.modelspot.com/mpx/minimag.htm
  23. Frank Skilbeck
    "Incidentally I thought it remiss of Spektrum to go on and on about the charger plug polarity, but not mention that a std Tx charger is the wrong voltage!" Good point but then again my 35 Tx is a Multiplex with a 6 cell battery so I never use a standard Tx charger
  24. Frank Skilbeck
    I thnk people mean Nitromethane, methane is what British Gas send to your house for your heating system
  25. Frank Skilbeck
    My LMS doesn't stock 35 mhz sets anymore, but does have 35 Rx's in stock. I have both a 2.4 and 35 and can't see me buying any further 35 gear, but then again my Tx is less than 12 months old and I have 7 or 8 35 Rx's. 2.4 is a boon in small electrics.
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