Hi all
Where should the thrust line for a nose FES go (ignoring for the moment down and right compensation for torque)?
In a related post John Mac describes having the thrust line for a pylon mounted motor go through the tailplane MAC.
Should a FES thrust line go parallel to the tail MAC, wing MAC or fuselage centre line?
Phill
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FES thrust datum line
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john greenfield
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Re: FES thrust datum line
Phil
Not used a FES but my turbine gliders had the thrust line parallel to the wing chord line (the line running from the leading edge to the trailing edge) and it worked well.
AEB
Not used a FES but my turbine gliders had the thrust line parallel to the wing chord line (the line running from the leading edge to the trailing edge) and it worked well.
AEB
AEB = Aeronautical Energiser Bunny (with thanks to CW)
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Phill Tadman
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Re: FES thrust datum line
Thanks Johnjohn greenfield wrote: ↑01 Oct 2017, 13:25 Phil
Not used a FES but my turbine gliders had the thrust line parallel to the wing chord line (the line running from the leading edge to the trailing edge) and it worked well.
AEB
Phill
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Elliot Howells
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Re: FES thrust datum line
Phill,
you'll find the thrust line of a FES will be dramatically different from that of a turbine. Experience has shown that anything up to 8 degrees down thrust is necessary - I'm not a aeronautical physics boffin, but having owned a few electric powered gliders from a large german (now korean) enterprise, these all have significant down thrust, my ASW17 I converted didn't have enough down thrust and needed a bootfull (fistfull?) of down mixed in to stop it looping.
SLS systems have a high thrust line due to the pylon nature of their construction, these have a positive incidence, which because it's behind the c of g is actually a negative incidence, hence the need to apply throttle gradually on roll out. (ask Andy Ellison about his DG). A turbine mounted in the same position is snug to the top of the fuz, so the offset effect will be negligible allowing a close to zero thrust line offset.
Have a look at multiplex blizzard, heron etc. that'll give you a good idea, then aim for something like 8 degrees, I would think the larger the wingspan, the less of an angle you'd need to counter, but certainly a 3m span model needed more than I gave it at 4 degrees.
Hope that helps, Ell.
you'll find the thrust line of a FES will be dramatically different from that of a turbine. Experience has shown that anything up to 8 degrees down thrust is necessary - I'm not a aeronautical physics boffin, but having owned a few electric powered gliders from a large german (now korean) enterprise, these all have significant down thrust, my ASW17 I converted didn't have enough down thrust and needed a bootfull (fistfull?) of down mixed in to stop it looping.
SLS systems have a high thrust line due to the pylon nature of their construction, these have a positive incidence, which because it's behind the c of g is actually a negative incidence, hence the need to apply throttle gradually on roll out. (ask Andy Ellison about his DG). A turbine mounted in the same position is snug to the top of the fuz, so the offset effect will be negligible allowing a close to zero thrust line offset.
Have a look at multiplex blizzard, heron etc. that'll give you a good idea, then aim for something like 8 degrees, I would think the larger the wingspan, the less of an angle you'd need to counter, but certainly a 3m span model needed more than I gave it at 4 degrees.
Hope that helps, Ell.
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Phill Tadman
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- Location: South Cambs
Re: FES thrust datum line
Thanks Elliot, useful stuff.
Phill
Phill