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06-21-2009, 08:58 PM
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#1 |
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RCC Master Contributor
I am: George S
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How many Gs do models pull.
We were just sitting around BSing at the field yesterday and we go to questioning what kind of G force a model can pull in extreme manuvers. Anyone know for sure? We were thinking 12 to 15 or so
George
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06-21-2009, 09:35 PM
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#2 |
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I am: Tom B
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Re: How many Gs do models pull.
QUITE A lot brought 2 aircraft home the other day. They pulled a lot of GS from the wife. No seriously what a model does would kill a human pilot. So I would say that in some your pushing at least 20 GS.f4u
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06-21-2009, 10:03 PM
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#3 |
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I am: john mcintosh
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Re: How many Gs do models pull.
I flew a friends Giant Scale Sweet and Low which is not aerobatic model. It was equipped with telemetry and it pulled almost 10gs from a 105 mph dive. I pulled it out slowly and was surprised at the g force.
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06-23-2009, 05:59 AM
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#4 |
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RCC Contributor
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Re: How many Gs do models pull.
You can estimate it based on speed, radius and orientation:
Centripetal acceleration = velocity squared / radius of turn. So, for example, if a model has a top speed in a dive of 100 km/hr (28 m/s) and you pull out of the dive with a turn radius of 20 m, Centripetal acceleration = 28^2/20 = 39.2 m/s/s To convert to G forces, divide acceleration by 9.8 m/s/s (earths gravity) G forces = 39.2/9.8 = 4 G's. Be sure to add 1 G for the pull experienced at level flight (at the bottom of the turn). So the total G forces is 5. If you are at the top of the turn, you subtract 1 G, since earth is pulling towards the center of the turn. In that case, the total G forces would be 4-1 = 3. Note that if you double the speed of the dive (maintaining the same loop radius) the G forces will increase by a factor of 4. It's no wonder we get to see wings snap from time to time.
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06-23-2009, 02:03 PM
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#5 |
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RCC Senior Contributor
I am: Greg P
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Re: How many Gs do models pull.
I have recently gotten into electric pylon racers. The one that I got, an Escape, has the wing stressed to over 50g's! Check out this video of an Escape to see why:
Escape Video |
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06-24-2009, 11:56 AM
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#6 |
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Re: How many Gs do models pull.
We purchased a telemetry system to measure G-Forces on a model airplane (as well as other items such as Altitude, Airspeed, RPM, etc).
As Bullwhip stated above, we were able to pull 9.87 positive Gs from the pullout of a steep dive from 2000 ft up travelling at an airspeed of about 104 MPH. You can read more about this on our Thunder Hangar Blog. Grizak
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