Thread Tools
Oct 30, 2015, 05:19 AM
Registered User
Greg Knipp's Avatar
Thread OP
Question

Looking for a home for my E-Flite 15


I have an E-Flite 15 sitting looking for a home. I have been eyeing up the Junior 60. Can anyone tell me if this would be a good fit?
Thank you in advance.

Greg Knipp
Sign up now
to remove ads between posts
Oct 30, 2015, 06:29 AM
Blueplaidcanard flyer
The 15 has a lot of snort,it will pull anything up to about 3.5 pounds and 1000sq.in. and not even blink.
Oct 30, 2015, 08:18 AM
I like real wooden aeroplanes!
Sundancer's Avatar
I've just looked up the E-Flite 15 and given that it is said to be for 3D aeroplanes up to 40 ounces and offers up to 500+ watts, I imagine you could have a supersonic J60! Vintage models need MUCH less power to fly well than your average sport/scale/aerobatic radio model. OK, so you can always tame the power by under propping and you do have a throttle, but I would venture to suggest that this motor might be a better fit in the J60's scaled up version, the Majestic Major.
Oct 30, 2015, 03:33 PM
Registered User
Greg Knipp's Avatar
Thread OP
Thank you so much gentleman for your advice. So them you guys are saying that this motor may be well suited in a 82" or 84" old timer.
Oct 30, 2015, 04:24 PM
I like real wooden aeroplanes!
Sundancer's Avatar
Quote:
Originally Posted by Greg Knipp
Thank you so much gentleman for your advice. So them you guys are saying that this motor may be well suited in a 82" or 84" old timer.
That's the sort of size of vintage cabin model I'd be thinking of for that motor. I know it is rated as being equivalent to a .15 IC, but that is under rating it's ability when it comes to vintage style models.
Oct 31, 2015, 12:36 AM
Registered User
Greg Knipp's Avatar
Thread OP
Yah I guess that is why I have such a problem matching motor to plane. I usually see that the norm is in the area of a .52 4 stroke in the 84" model vintage style planes and .35's in 72" span ships. These brushless must have way more power as opposed to their slimer counterparts.
Oct 31, 2015, 12:54 AM
B for Bruce
BMatthews's Avatar
A safer bet just in case the weight comes in a little over what you expect would likely be a 72'ish span. But there's LOTS of good designs in that size range.

Consider that just for power to weight that 100 watts per pound of model will give you a climb that is just shy of vertical. Like we're talking 70 degrees angle nose up and not exactly hanging on the prop here. We're talking heading for the clouds at a spirited rate.

So yeah, the names we give these motors means little. Instead you need to look at the wattage that the motor will comfortably handle and then for a sporty but not rocket like climb rate figure on around 70 to 80 watts per lb of model weight as it sits in your hands just before it heads out. Or you can look at having 100 watts/lb and use the throttle lever judiciously. Other than the odd near vertical climb just for giggles you'll never need or want to use the full 100/lb.

With most 6 foot old timers I would not recommend full throttle in level flight at that sort of power to weight ratio. The speed on a classic old timer this would produce might well result in explosive flutter of the wings or tail surfaces.
Oct 31, 2015, 01:29 AM
I like real wooden aeroplanes!
Sundancer's Avatar
Another factor to take into account is wing loading. That E-Flite 15 would EASILY fly a 120 to 140 inch glider with an entirely adequate climb, and the bigger vintage models, apart from being more draggy, are more akin to gliders in the wing loading department than to what we have become used to considering as sport R/C power models in IC terms. You have to remember that when models like the Powerhouse etc. were originally flown, the ignition engines used were producing a lot less power than a modern IC equivalent. Adding modern lightweight radio hardly has any effect on the overall weight or wing loading of an 84" vintage model, therefore they will still produce entirely satisfactory performances on power equivalent to those IC engines used in the original way back then.

And, whilst having a reasonable reserve of power available for ROG and emergency "go-rounds" is prudent, as BM correctly says, if excess power is used unwisely, vintage structures can be pushed beyond safe limits. Of course, you CAN beef up structures, change wing sections etc. but then you finish up with what is really a "vintage looking" sport power radio model which, for electric power, will require power equivalent to the size of IC motor that would be used in such a model, in which case the "IC equivalents" applied to electric motors become more relevant.
Oct 31, 2015, 06:00 AM
Registered User
I can see no problem whatsoever in using an E-flite Power 15 in a Junior 60. Yes it has the potential power to fly a Majestic Major but you don't have to prop it to that power.

Running a few numbers for the E-flite Power 15, if we said 75W/pound is ample max power for a J60 and the model weighs 4 pounds then a target power input would be around 300W. Running these figures through Drive Calculator for a 3 cell LiPo and an 11x5.5 APCe prop gives us:-
Input power 304W
Current 28A
Pitch speed 45mph

The above looks fine to me, in fact those figures are very similar to those for my own electric J60 which performs superbly on a similar spec Scorpion motor.
Oct 31, 2015, 07:07 AM
Registered User
Greg Knipp's Avatar
Thread OP
Thank you all for helping me understand.


Quick Reply
Message:

Thread Tools