David RAFster Martin

David, Thanks for the pic of the cover for the US version!Now I can see if I can find this US version of the Special edition. Hastings store here in Sierra Vista doesn't have it and we don't have any Borders or Barnes and Noble stores here. Those stores are in Tucson so I'll have to give the newstand a ring tomorrow to see if they have the R/C Model Aeroplane issue with the Lysander. I have a doctor's visit next Monday so I will drop by to get it if they have it then...  Going direct purchase would be spendy, around $18.50 US (L11.50) with shipping. If I end up going that route I think I would purchase a few other items to lower the effective shipping cost per item...  Time to go to bed, I have a headache and 6AM will come too early... Thanks! David

Have my name in at a magazine stand in Tucson that carries RCM&E and have been waiting for it... They haven't called yet and it is mid October... Did you say something about another title on the cover for US folks?  Huh? So, it won't be published under RCM+E but under another RC magazine title? If so, please explain...   David Martin Sierra Vista, Arizona USA   P.S. Tim's Lysander was a hoot, there was an RCG build thread on it. Tim, you should post a link to it. Apparently a gun emplacement in the tail for a tailgunner. In case they got jumped by ME109s or FW190s? Wouldn't be a good situation to be in since they Lizzie was not a fast aeroplane. I see the construction Tony used and man does it look like a heavy bird...guess it will be more crash-damage resistant that way... For electric it means a  bigger motor and battery load. to haul around the structure...nice thing about electric, You don't have the fuel mess and vibration issues present in glow setups and can build it lighter as a result.  

Higher outputs stressing the motors at limits still need excellent cooling. Some motors will overheat and burn up if bench ran on the ground for too long with props that are manufacturer's specified ranges with "excellent cooling"Maybe it is folks have gotten more advanced in ensuring there is cooling air through the motors and through the fuse across the batteries. Ensuring that the air exit size is adequate as well. There is a lot more information available in modeling magazines on electric these days. So, I agree in part with your statements Erfolg but not in total.  Oddly enough pusher jets with the motor fully exposed sometimes have to have a cowling put around them to force air through and around the motor for cooling as the motor mount and fuselage will "blank" the motor providing very poor cooling. Some of the Little Screamers motors are succeptable to burning up in pusher designs if not careful to "push" some cooling air through the motor. The LS motors are around an ounce in weight and have power output between 150-250W or more depending on the model.

Posted by Myron Beaumont on 13/09/2009 12:44:29: Timbo First of all may i say how useful your series of threads have been. Wished they'd been available a while back but brilliant for tying up loose ends to a near beginner to 'lekky stuff!So  going back to my original query -What sort of weight/prop relationship is possible without smoke.Can I use a biggish prop & not use full "throttle" The wood is waiting g-umpy2 !   Myron,  Just thought I'd stir the pot on the ESC smoke generating idea of part throttle.  You can't overload a motor with more amps at full throttle than the motor or battery can deal with full time by just throttling back. The problem is that the ESC (Electronic Speed Controls) provide part throttle by turning on and off the power at a percentage of time based on the controller's frequency to average the power provided by the motor at an average output that corresponds to your throttle stick setting.  So, if your prop setup on your motor is going to draw 30A at full throttle and your motor is recommending 20A max for 30 seconds and 15A continuous. And say your battery is a 15C model and you are going to keep it at half throttle  and you either calculate or measure it to be drawing 20A at 1/2 throttle then you think well, I should be able to get away with a battery that can provide 20A at 15C and that minimum for short flights would dictate it to be a 1500 mAH capacity could supply 22.5A at its recommended continuous so, I'll be good.  You might find trying to use a 25A ESC and 1500mAH 15C LIPO  to make sense...Problem is you will be overheating and probably destroying the battery in not too many flights and the smoke is probably going to be let out of the 25A ESC as  well in a bit of time if the motor doesn't smoke first. You'll quickly find your packs swelling, or  going dead after not too many flights in that setup, or maybe even worse the swell and burst under load causing a fire.  So, propping down you find you don't have the thrust you need or watts you need to provide the power at the throttle setting you need. Requires a  larger  motor then... Pitch speed and watts are important for your motor selection I think. You can get a motor that is rated for 150W and it is capable of that 150W but it is suitable for a light 3D airplane or lightly loaded plane as it will  handle the 9x6 prop and provide 15 oz  of thrust but the pitch speed is 30mph. Not going to fly a big  plane that weighs 16 ounces very fast and it could be marginal performance. The kV has a relationship to the prop size as Timbo has pointed out.The problem we modelers often have is the kV is something manufacturers latched onto as is the Wattage of the motor. Or they tell you it can handle props from 7x5 to 9x6 but don't provide any pitch speed measurements for the thrust and amp draw tables they will provide.The kV isn't a 1:1 relationship with the voltage applied as the prop loading impacts the current and motor efficiency.  For the the theoretical draw of 30A full throttle you need a 40A ESC to provide some room for error and you should select a battery size on capacity and Amp draw and being conservative in battery current demands will generally provide more cycles from that pack than running near the max. If you can handle the weight of the larger pack you generally benefit from the larger packs ability to sustain current draw without voltage depression if you are asking it to deliver between 1/2 and 3/4 of its rated continuous capacity...err on the conservative side toward the 1/2  mark will generate less heat from your battery and heat plays a role in Lipo battery life.  So, if we need a 40A ESC and we need to size the battery for the 30A draw then you want to look at a pack that can deliver between 45 and 60A  at recommended draw ratings.So, that translates to something like a 3000 to 4000mAH pack... Side benefit is that instead of a 3-5 minute flight you can look at a 10-12 minute flight.  Then there's the 3S vs 4S or higher lipo packs... if  the motor & ESC can handle higher voltage of a 4S or higher pack you can run higher voltage packs and draw less current to obtain similar wattage settings which allows you to have more relative capacity in the pack and it give  you longer flight times because of lower amp draw.  What I've learned about electrics is there are many factors and figures most motor makers won't provide you enough to figure everything out to see if the motor will give you the pitch speed (rpm related and prop pitch related) and Amp draw and wattage for a particular motor (kv known) and prop combination. Often you see huge thrust numbers and you find the pitch speed to be too low for the performance you seek.  Eflite is one maker that has tried to size motors to glow equivalent. The Eflite 10, 25, etc. are motors that can spin similar prop sizes as the glow engine and provide flight performance that is similar. David

Posted by Timbo - Moderator on 14/09/2009 19:20:37: Oh Ok... there are a few high Kv outrunners knocking about...but as I say, thats a high Kv and suited to small props like a 5 X 4 or summat similar. Indeed you now say its from an EDF originally, so, there you go. No good at all for a WOT4 type model!Edited By Timbo - Moderator on 14/09/2009 21:01:05 Myron - I think you might want to consider putting that setup in a small pusher jet similar in size and weight to the jetset44 designs on RCGroups of the depron or FFF line of pusher jets.With that KV the 5x4 or 6x3 electric prop might be it's max. APC E props (not SF props) would be in order.  You won't be likely to see the 28000 rpm when loaded and you need to keep in mind APC's recommendations for their props as well so you don't over rev them and fatigue a blade/blades to the point of having it shed a blade. Definately balance your props just like if it was an IC motor.  If it sheds a blade you'll likely have the motor rip itself out of the plane and  you may not figure out what caused that, if the motor doesn't separate from the plane until impact with the ground as you won't recognize what happened as it isn't uncommon to lose prop blades in crashes...  Measure on the ground in a short run up with the props with a watt meter and tach to see what you are getting.  Several motor designs won't tolerate long bench runs on the ground; especially high performance designs.  David Edited By Timbo - Moderator on 19/09/2009 08:44:43

Kelvin,  Sorry to see her nose in that condition... Sounds like the climb was way too steep and she stalled and bit you for your trouble. But, like you said, some glue and new prop and she'll fly again... Of course you will check your incidences when you glue it back together as you don't want your firewall to change the thrust angle and cause issues. Good luck putting her back together and the coming re-maiden event. I have one of these kits on the shelf and having seen video of one flying on RCGroups I know my skills won't equal what she needs... David

621 posts, busy thread with lots of people who want to win the prize... Lady Luck should smile on one person.  David

BTW, Last of the Many (PZ865) is now displaying the JX-E colors I posted earlier...

Tony, I am a fan of the "Night Reaper" from the Czech ace who was a top ace night fighter. He received the DFC and Bar. Karel Kuttelwascher's "Night Reaper" BE581. The photo I've posted is of the Memorial Flight's Hurricane done in the scheme to honor his achievements. Coincidentally, the top scoring ace in the Battle of Britian was also Czech. JX-E coding, black undersides and rudder with green and grey camo on top. Scythe in yellow and Night Reaper on the red banner on the right nose panel. An article about the ace's career in the RAF: http://www.rogerdarlington.me.uk/nighthawk.html  David Martin