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Old Jun 28, 2006, 01:26 PM
Jaded Flyer
mcharles13's Avatar
United States, FL, Clearwater
Joined Aug 2004
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Can someone clear this term up for me?

What does it mean that a planes holds it's energy well?

I've heard that mentioned a few times about good planes holding their energy but have no idea what that means.

Anyone who could enlighten me please do so, i will be very appreciative.
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Old Jun 28, 2006, 01:39 PM
Flying...Pushing Air Down
sr71fan's Avatar
Clovis, NM, USA
Joined Nov 2000
3,561 Posts
Energy

Example: Maintains a good portion of its airspeed after an aggressive maneuver.
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Old Jun 28, 2006, 01:47 PM
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oh ok i got it. that makes a lot of sense. I have a plane that i dont fly often that doesnt maintain momentum well. After a maneuver the plane wants to fall.

So what factors contribute to a good plane like this?
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Old Jun 28, 2006, 01:51 PM
Needs a vacation
thermlin''s Avatar
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plenty of power, decent weight (not too heavy or light)
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Old Jun 28, 2006, 01:53 PM
Where's your CofG?
Gibby's Avatar
San Diego
Joined Apr 2004
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Most of the time that term is used by the F5B folks and, in F5B terms, it simply refers to a planes ability to maintain it's speed once the power is cut. A plane that has good energy retention basically has very low drag or wind resistance. In F5B, planes basically race around two pylons using gravity to maintain speed through the course. So an F5B pilot will use the motor to climb to altitude and then keep the plane pointed down hill to keep speed as they go around the pylons. The better energy retention an F5B plane has, the faster it will be through the course and the more pylons the pilot will be able to get around before they have to power on and climb back to altitude. I hope that wasn't an over exhaustive explaination.

Gibby
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Old Jun 28, 2006, 01:54 PM
Where's your CofG?
Gibby's Avatar
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Crap I type slow, three responses before mine!!!
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Old Jun 28, 2006, 01:56 PM
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elfwreck's Avatar
United States, CA, Oakland
Joined Dec 2002
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Hey now,
The factors that contribuite to good energy retention are all exemplified by slope racers, F5B/D models and hot liners. Low drag, thin wings, tiny frontal area, smooth lines and seams where the hinge lines are, and enough mass to hold inertia.

Things that detract from this are: fat airfoils, things hanging out in the air like servos, pushrods, control horns, landing gear, struts, big round noses, open canopies with draggy pilot figures, even canopies and tail surfaces add to this problem.
RobII
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Old Jun 28, 2006, 02:19 PM
Where's your CofG?
Gibby's Avatar
San Diego
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Good point I left out the Slopers and the DS ships.

Gibby
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Old Jun 28, 2006, 02:20 PM
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Pacific Palisades, CA
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An F3f slope racer is the perfect example of energy retention. It will come out of a 180 degree, full elevator banked turn seemingly as fast as it went in, or even faster if it was an upwind turn.
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Old Jun 28, 2006, 03:34 PM
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ok now define F5B. i know it is pylon racing but what does the F5B stand for.
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Old Jun 28, 2006, 04:42 PM
Flying...Pushing Air Down
sr71fan's Avatar
Clovis, NM, USA
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...
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Old Jun 28, 2006, 04:57 PM
AMA 754
BobRCnut's Avatar
Phoenix area
Joined Apr 2004
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F5B, F3A, and similar terms are the designations for different competition categories as defined by the FAI (Federation Aeronautique Internationale), which is the worldwide governing body for aircraft competition of all types (not just models). I believe the categories are documented on the AMA web site and in the AMA Competition rules book.
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Old Jun 28, 2006, 08:51 PM
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United States, CA, Oakland
Joined Dec 2002
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Hey now,
F5B is a FAI term, the F stands for models, the 5 stands for electric, and the B is the specific task or tasks.
F5B is a multi-task event where you power up and climb, shut the motor off and dive into a pylon course, you dop as many laps as you can, powerup, climb and repeat the process. There is a set time for the pylon part, then after the first task you climb out and thermal for a set number of minutes then land in a thirty? foot circle. Fairly simple tasks really, but to do the laps fast, thermal well, and land at zero seconds is harder than it sounds, and doing it against other folks who train seriously for the event is really hard.

So, you need not only a very fast model, but one that retains energy very well. That's why we point to F5B models to show the epitome of energy retention.
RobII
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Old Jun 28, 2006, 11:45 PM
Castle Tech
Joe Ford's Avatar
Olathe, KS
Joined Aug 2003
4,890 Posts
Good explanation Rob.

F5D ships (the pylon racers you're thinking of mcharles13, motor on 100% of the time) also strive for high energy retention...sleek airframes, different objective. One factor that was not mentioned is weight. Very generally speaking, the heavier it is, the higher the energy retention in turns (but there is a limit).
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Old Jun 29, 2006, 07:09 AM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
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Good point, Joe. Sleek airframe can't be overlooked - it's not just power and weight. My Siren is fast and moderately heavy, but the wing is draggy, so the model slows quickly without power, especially in turns. The most common complaint about the siren is that it doesn't retain energy well (but for a beginner to hotliner flying, this is actually desirable, especially for landing!)
..a
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