Motor calculations for Grumman Albatross - RC Groups
Jan 28, 2002, 04:17 PM
Registered User

# Motor calculations for Grumman Albatross

Can someone explain static thrust and inflight thrust to me? I was putting some numbers into P-calc, seeing how increasing gearing reduces amp draw, and I noticed static thrust went up as I increased the pitch (I expected that) but inflight thrust went down.

Here's what I put in:

motor: Speed 400
Prop:....................7x3........7x5........7x6
Gearing:................1:1........2:1........2:1
Amp draw:............16.3.......9.9.......10.7
RPM of prop:.........9810......8274.....7863
Static thrust oz:....12.4.......14.7......15.9
Inflight thrust:.......14.3.......10.2.......9.2
Pitchspeed mph:....27.9.......39.2......44.7

Here's why I'm curious. I ordered a Grumman Albatross from Hobby Lobby (last sale) and I was thinking about using gearboxes to reduce the amp draw for longer flight times. I also read some treads about people having problems taking off from water. Would increasing the static thrust help that?
 May 17, 2007, 04:19 AM Electric forever, Interesting stuff. I'm gona get a flying boat as I can use a nearby lake. I'm looking to use my old Twinstar stuff so Im looking a the "albatross" or an "Aventura III" I notice this is an old post. What did you settle on in the end and how do you think it compares to the aventura III? http://www.rcuniverse.com/magazine/a...TOKEN=86430768
Apr 22, 2009, 06:14 PM
Registered User

# Static vs. Inflight thrust

Hi Van,
Static thrust is the thrust measured with motor and propellor mounted in a fixed position such as a test stand. In flight thrust is the measured thrust when the motor and propellor are actually in forward motion. A propellor is far more efficient when it is moving forward than it is when it is stationary. Hope this answers your question. Brian Milsom
Quote:
 Originally Posted by Van Can someone explain static thrust and inflight thrust to me? I was putting some numbers into P-calc, seeing how increasing gearing reduces amp draw, and I noticed static thrust went up as I increased the pitch (I expected that) but inflight thrust went down. Here's what I put in: motor: Speed 400 Prop:....................7x3........7x5........7x6 Gearing:................1:1........2:1........2:1 Amp draw:............16.3.......9.9.......10.7 RPM of prop:.........9810......8274.....7863 Static thrust oz:....12.4.......14.7......15.9 Inflight thrust:.......14.3.......10.2.......9.2 Pitchspeed mph:....27.9.......39.2......44.7 Here's why I'm curious. I ordered a Grumman Albatross from Hobby Lobby (last sale) and I was thinking about using gearboxes to reduce the amp draw for longer flight times. I also read some treads about people having problems taking off from water. Would increasing the static thrust help that?