e300s

Hi all, i was woundering if a hitec HS-645MG servo will be good for a giant scale (80.5" wing span) extra 300s. also would a 45cc engine be ok in this size aircraft or is it too much overkill. it says the model is for a 160 glow??

servo specs:


Motor Type: 3 Pole
Bearing Type: Dual Ball Bearing
Speed: 0.24 / 0.20 sec @ 60 deg.
English Metric
Torque: 106.93 / 133.31 oz.in (4.8v/6v) 7.7 / 9.6 kg.cm
Size: 1.59" x 0.77" x 1.48" 40.60 x 19.80 x 37.30mm
Weight: 1.94oz 55.20g

BuschBarber

My Feedback: (2)

I am currently flying a Great Planes Patty Wagstaff Extra 300 (78") with a ZDZ50.. The plane weighs 16lbs. I have an 87" Extreme Flight Yak54 with a DA50. It feels much lighter in the air than the Patty, but both fly well. At our flying field, we need cannister mufflers for gassers. The Extreme Flight Yak has a tunnel and a cannister. The Patty has no tunnel and I am using a Bisson Side Mount muffler and a 3 blade Mejlic 20x12 prop to keep it somewhat quiet. The EF Yak has a Mejlic 23x8 prop and is very quiet.

It is OK to go to a larger motor than specified by the Mfg, if you do not pat too much of a weight penalty and jack up the wing loading too much. If you underpower a plane, it will not be a very good performer and will be tough to get out of trouble if you make a mistake.

A.T.

Answered under cross post

Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links

XJet

The HS645 is a medium-power servo with average centering and resolutino.

It would work okay on ailerons or elevator-halves (one one each side) in the application you describe and if you're not into 3D then it'd probably cope with rudder as well.

Used to be that I only ever used Hitec servos (I've two HS645s on each of the ailerons on my 90" Extra 330L) but these days there are better-value options on the market.

The biggest disadvantage of the HS645 is its speed. It is dog-slow on 4.8V and not really that much faster on 6V. The 645 gains its torque by using more reduction in the geartrain and that means sacrificing speed for power.