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Jan 28, 2002, 03:17 PM
Van
Van
Registered User
Van's Avatar

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?
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May 17, 2007, 03:19 AM
Electric forever,
twinstarchris's Avatar
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, 05:14 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?


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