PatMc

I've had similar problems in the past. Changed all the plumbing etc sometimes cured it but on two occasions only changing the fuel tank was successful.  I think sometimes small pieces of a waxy deposit from previously leftover fuel accumulate inside the tank walls, they float free as small globules but are virtually invisible in the fuel line. Sometimes you can detect a build up of these globules in a fuel filter. Unless you can flush the tank clean of any contamination before filling with fresh fuel it'll just keep on happening. TBH it's easiest just to change the tank.

Sounds good Andy, how about some close up pics of the various parts. In particular the internal nose area, servo/Rx bay & battery space. 

Stephen use bike spoke wire instead of piano wire. It's easier to bend & cut. A method you might consider is to glue cut down plastic control horns (or better make something from 1/16" ply or g/f board scraps) in each of the strut anchor points. Epoxy a hooked piece of spoke wire to one end of the strut & a threaded end to the other. Fit a clevis to the threaded end & adjust for length.    

Mount the servo as normal & let the wires find the path.

John, are you starting the flight using conventional throttle then changing to switched in glider mode ?

I've used 27MHz & 35MHz AM & 35 MHz FM, in various electric models for about 12 years or more without any interference problems other than a short range 35 MHz Rx at an indoor venue. Never tried EDF or helicopters but I do know of at least one person who definitely had issues with an EDF that disappeared when he went 2.4 GHz.   

Paul, because a motor coil is inductive it takes time for the current to build up when it’s switched on.(Lenz Law) Now as I understand it the purpose of advancing the timing is in order that the current is at it’s max as the coil is fully aligned with a magnet. This is also the point that the back emf generated in the coil is at it’s max. The sum effect would be the greatest repulsion force between coil & rotating magnet (torque) at the same the current is limited being by the maximum back emf. Output power would be maximised & resistive (copper) losses minimized giving best efficiency. Without knowing the rpm for each of your test figure I can only guess what they mean. If the 1 deg gives lower rpm than the 7 & 15 deg it’s probably because the current hasn’t enough time to build up fully so the motor isn’t developing full power. If the 30 deg gives lower or only a little higher rpm it’s because of increased copper losses & the energy conversion efficiency will be down. The 7 & 15 deg setting may be bracketing the ideal point but this will vary as throttle is used & as the battery runs down. If I’m right there may be a difference (possibly small) in rpm between these two settings & 7 deg might be a good comprimise if you use mid/low throttle in flight even if the rpm are less than 15 deg at WOT. With a hotliner or short WOT power bursts in a E glider 15 deg might be best if it gives more power. 

Posted by Phil Wood - Moderator on 03/08/2009 19:57:38: In the situation he's described he'll never get the fuel level in the tank higher than the pressure pipe and he may be flooding the carb as he's filling.  Polyphilla.  Unless he fills with the model inverted.

It doesn't make any difference whether the pipes going into the fuel or the void. If it was in the void upright it would be in the fuel when the model was inverted.Typed before next post appeared. I'm referring to the running of the engine. Edited By PatMc on 03/08/2009 19:50:28

I tried to answer the points raised in Erfolg’s last post in a logicaly formatted order but cocked it up because I didn’t notice the “paste from Word” icon. I’ve had a severe talk with myself & will try again.   All the quotes in italics are from Erfolg’s post, the plain font replies are mine.   Quote:  All (well two of them) of the manufacturers clearly state that their controllers always apply full power. The speed variation being achieved by the duration of the pulse. This implies that the frequency is constant.   The pulses are at applied within a time frame for each phase. That time frame is divided into a mark - space (on – off) period. The power in each pulse is achieved by varying the m-s ratio. The speed is varied by the power of each pulse matching the resistance of the load. If the frequency was constant the coils being energised would be in a random position wrt the magnets when the pulse occurred unless the motor only rotated at a harmonic of the frequency.     Quote: It is also written that higher frequencies settings are better for the ESC, in low pole count motors, …   The Hyperion ESC instructions I have state the opposite.   Quote:  However in high pole count motors …due to the higher switching rates.   This seeems to contradict the previous statement.   Quote: In reality I am not clear how to use this statement. As it seems to imply that outrunners should be set to the lowest frequency possible for satisfactory operation, and that most inrunners will need a higher frequency.   For the reasons given in my previous post which ties in with Hyperions statement “The ESC must be able to switch at the operating rotation x number of poles x number of phases.” This means that a 2 pole 7000kV motor, a 4 pole 3500kV & a 14 pole 1000kV would require the same switching frequency at the same supply voltage.   Quote: Most of the sites advice that you should start soft and go harder if necessary.   If “hard” & “soft” refer to timing that’s not the same as the switching frequency. Edited By PatMc on 02/08/2009 20:13:38 Edited By PatMc on 02/08/2009 20:15:25 Edited By PatMc on 02/08/2009 20:16:19

Sorry about the gobbldygook & random smilies in the last post but I seem to have upset the site software gremlins. If someone could please delete my last two posts I'll try again.

Adding nose weight doesn't help in windy weather if the model's already correctly ballanced. How about the  GWS Formosa  equipped with a brushless motor & 3s lipo but leave off the undercarriage.

1. Use the same cg. But if anything try & move it back for a more efficient glide. 2. For best range of options use without ballast in light wind conditions then add ballast according to windspeed. I have an old Protech Unlimited that was bought s/h complete with a spare fuselage & tail unit. I modified one fus to take a b/l motor & 3s lipo & the other to pure glider by installing the Rx batt, rudder & elev servos as far forward possible. A lump of lead was stuck in a spare spinner fixed to the nose to bring the cg to the same position for both versions. There's about 10 oz difference in weight between the versions - wing loadings are EP 15.5oz/sq ft & glider 12oz/sq ft.  Aerobatics (on the glide) are a little crisper with the EP version but the model flies fine in both modes.

Hi Doug, an  ESC isn't an inverter. It is provided DC pulses to do the same job electronically as a brushed commutator does mechanically.  Our B/L motors are powered & controlled as DC machines which is why kV is one used as of the defining parameters. The motor speed is a function of applied volt but practical operation is a function of frequency. The ESC must be able to switch at the operating rotation x number of poles x number of phases. e.g if we have a 3s lipo giving 12v whilst supplying a free running 1000kV 14 pole motor then the minimum frequency will be 12 x 1000/60 x 14 x 3  = 8.4KHz.Of course with a load the voltage will drop & motor rpm subject to slip therefore the frequency would be too high. The ESC senses the coil/magnet relationship per phase & only "fires" at the necessary frequency. Don't know where you get the volts per Hz relationship from but it doesn't compute. If it did the same motor  that needed 440v @ 55Hz would only need .95 mV for correct operation. As far as I'm aware there's no relationship between applied voltage & supply frequency.  

Posted by Terence Lynock on 01/08/2009 21:26:23: P.S if I had any say the Elgin Marbles would be on their way home sharpish.Edited By Terence Lynock on 01/08/2009 21:28:16  I definitely agree with you there,Terry.

Ken - wash your mouth out this instant.  Pat.

Terry, do you think Germany can claim that a FW 198 is "of national and historical importance" ? I don't.  If rightful custodianship of works of art & historical artefacts were to be challenged  for items as unimportant as this aircraft the world's museums would be deluged by return demands.The only German aircraft our own museums might be able to retain rightful ownership of would be those Fieseler Fi 103s that were sent here as unsolicited gifts.  As far as "...certain countries in this world that have an obsession with collecting other peoples history which in turn robs those countries of their heritage" I'm afraid Britain must be one of the worse offenders.   The Stone of Scone is only back in Scotland conditionally.  Cheers,Pat.

If you follow the menu through from here it will take you to equivalent multi blade props but to save you the bother changing from 2 >4 works out as a reduction of 16% dia. But there is a caveat "valid only for propellers of the same family having similar blade shapes".

Would you have any objections if the FW 189 had remained in UK where it also has no more historical significance than it has in the USA ? As for works of art, in the UK we hold historical artefacts from Egypt , Greece & numerous other countries. Should they all be returned ? Should the Stone of Scone be returned to Scotland & the Lindesfarne Gospels to Northumberland etc etc ? 

Erfolg, I wasn't saying I was in any way confused by BEC V LVC. Merely giving this as an example of a common confusion that could have a parallel with a possible confusion re ESC timing.  Doug, I'm afraid that formulae doesn't directly apply to our situation, it relates to AC machines. If it did apply we would achieve the same rpm minus slip at any voltage for a given supply frequency, throttling would be achieved by varying the frequency & only a single ESC would be required for multi motors models.  BTW I think the formula is normally given as RPM = 60f/np Where f is the frequency in Hertz & np is the number of pairs of poles. 60 converts the measurement of frequency in seconds to that of rotation in minutes.        

Erfolg, some of the instruction sheets contradict each other as to which settings to use.Also when timing is being described or discussed I think there is some confusion between the rate of commutation & advance/retard function of a phase being energised in much the same way as there's confusion between BEC & LVC.     

Either an APC 5x5 or 4.75x4.75 should be about right.  It's a bit suck it & see though.The motor's only rated to 18A so best to try it with an ammeter connected, opening the throttle gradually.  If you try a 5x5 first & the meter goes above 18A then you should repeat with the smaller prop. If the reading is well below 18A & you don't think there's enough power you might want to try the next size prop up - a 6x4.   

What about one of the 12v nimhs listed here Vapextech Your existing charger would suit it fine. Or if there are any long time electric flyers in your club have a word with them. One of them would probably still have some perfectly useable but now redundant nicad or nimh batteries for the price of a pint or so, I know if anyone at my club was in your situation I'd be happy to oblige.

Posted by Chris van Schoor on 30/07/2009 16:29:40:  To encourage someone who is looking for his first glider (see OP) to possibly convert from rubber bands to bolts is foolhardy and ill-advised.  To convert a vintage model that came out with rubber bands to bolts is even worse.  Rubber bands do not add significant drag (we are not talking about competition mouldies here), and are an exceptionally good way of absorbing energy on landing that would otherwise have to be absorbed eslewhere in the airframe.  Looks (on the ground) are hardly top of the list of priorities for a first glider.  If you do not like some other aspect of the design of the glider referred to, please point to that, not just the fact that it uses rubber bands, which is not a reason for the OP to discount  particular model. Chris, you seem to be expounding your own opinions as if they were facts.  I wasn’t encouraging the conversion of the model to bolt on wings – merely stating a personal preference & I certainly wasn’t discounting the model from consideration – quite the reverse. So far your only contribution to Simon’s request for advice on choice of model is to negatively pick on a small part of one of my posts & then rudely attempt to build your own apparent aversion to bolt on wings around it.  If you care to have a look at Simon’s photo gallery you’ll see that although he wants advice on his first glider he already has several other relatively advanced models. I suggest that he won’t find landing a glider on a flat field too onerous if he can land these models reasonably competently. It would be hijacking Simon’s topic to debate the merits of different wing fixings so I won’t continue the subject here but if you wish to raise the topic in a new thread I would be happy to argue the point – politely.  BTW can’t make sense of your remark re converting a vintage model to bolts. Edited By PatMc on 30/07/2009 21:58:10

Scott, I'm not sure what your examples are meant to prove.All you're saying is that hard timing increases the power consumed by the motor/load in each example given. The same would apply in the case of an ic engine if it were run rich but the rpm would drop.