Bandit 557

Need Help! I'm going to build this little glider from pink foam to help teach a young man of 82 how to fly. How ever I have no idea of how to select the correct sized motor, battery, folding prop. esc. package for this little plane. Speed and high rate of climb would not be important with this plane. Any and all help would be great.

Thanks

Bandit

RogerParrett

Start here...

http://www.electrifly.com/config/


Best of luck!

Roger Parrett

OzMo

My Feedback: (3)

nice drawing but the info needed would be weight ,wing span. Good on you though for helping the "youngster"

Bandit 557

Thanks for the replys. The weight is unknwown at this time, but 15 - 18 oz. should be in the ball park. The wing span will be 59 1/4". It will use a simple three channle radio, with HS-81 servos.

Thanks

Bandit

BMatthews

Make the fuselage out of something besides pink foam. Or "harden" it with some sort of fiberous skin material bonded to the foam. Otherwise it'll snap easily.

Another option would be to redesign it as something more along the lines of an old timer free flight model. That way you can put on some landing gear. But primarily the foam of the fuselage will then be thicker and deeper and would be able to resist most of the "arrivals" with no damage. And having a bigger fuselage for his "young guy" eyes would likely make it a little easier to see what the model's attitude is in the air. And a good visual identification of the model's attitude is a key factor in being able to fly the model well. If you opt for a more cabin fuslage like design take from the old timer free flight style models then I'd also suggest you just go with simple V dihedral. Despite the dumpy looks of such a design if you keep it light in the low 20's to high 'teens in ounces such a model will still thermal soar.

Either way if you stick with a design that is this light then you can get away with many of the "all in one" packages very nicely. Likely a more realistic weight for the model with all the gear is in the 22 to 24 oz range. So let's call it 1.5 lbs. Spirited climb rates and flying speed is easily had from using 70 watts per lb which is all you need or want for a trainer. So a power package which will handle around 100 to 120 watts is fine.

At http://rchotdeals.com/Products/rc/Br...orsandESC.html
the B2212/10 combo motor and ESC would be a nice setup and it comes with a prop saver. A highly desireable bit of kit for flying with no landing gear or on rough fields. The page on the motor suggests an 8x4 prop for use with 3S lipo packs which would be a good way to go. And the prop saver is not so much for the prop but for avoiding bending the motor shaft or ripping it off the mounting plate. So I highly recomend using a motor with a prop saver mounting feature.

At Hobby King they have lots of possible motors and ESC's but no combos in stock at the moment. But if you want to buy there then any of the motors which list themselves in the 1200 to 1500 Kv range and are listed as good for 13amps max continuous or more or 130 watts would be OK to use. Match the motor with an 18 to 24 amp ESC. Be sure you can get a prop saver with the motor as well.

For battery packs you don't want to haul around tons of weight. But you want a nice long motor run. In level flight the model is going to use only about 20 to 25'ish watts to remain aloft at the lower throttle cruise setting. So even a modest size pack will last a goodly amount of time. Average out some climbing as well as the cruising and let's call the average power consumption 30 watts. Since watts is amps x volts a 3S pack at 11.2 volts providing 30 watts is only being drained at 30/11.2 = 2.7 amps. The battery pack capacity is based on amp hours. So at an average power output of 2.7 amps a 2700 mah pack would last a full hour or near enough. But such packs weigh just a bit under 10 oz in 3S configurations. And frankly an hour is just not needed. So I'd suggest you go with packs more around the 1200 to 1500mah size. That'll still easily give you enough power to get two medium or three shorter flights out of a single pack. Buy two and a proper charger and by the time you've done your flights from one pack the other will be just about ready to put back in for more fun.

aeajr

My Feedback: (2)

For a glider of about 20 ounces you would want a motor/battery combo that would give you about 75 to 100 watts for a power to weight ratio of  about 60 to 80 watts/pound.  About 70 watts/pound should give you about a 45 degree climb.  

This combo would work well.   Motor, prop, ESC.
http://www.maxxprod.com/mpi/pdf/combo-061-10-15.pdf