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Old Jul 18, 2016, 08:34 PM
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Should I worry about wide-set twins?

If I were to build a twin fan jet with the fans set apart 12"/30cm or more, should I be concerned about the torque of both fans spinning in the same direction?
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Old Jul 19, 2016, 01:44 AM
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Does a fan make torque?
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Old Jul 19, 2016, 05:23 AM
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The best way to be difference direction.

When the fan getting start I can feel the counter-acting force.

So two fan together should be have difference direction.

Personal idea!
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Old Jul 19, 2016, 06:27 AM
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I've never noticed any effect during flight flying twins or singles. ME262, A10,SU34,B737 are some of the models. It isn't worth buying opposite direction fans IMHO.
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Old Jul 19, 2016, 06:36 PM
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Thanks!
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Old Jul 20, 2016, 02:07 AM
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Twin fans

The biggest problem would be asymmetrical thrust should one motor quit. Had a fan blow apart on my A10 without to much of an issue and made a perfect landing with one fan. Check out the MD-11 UPS.
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Old Jul 20, 2016, 09:21 AM
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If they are wide set just mix them with your rudder and do some flat spins with variable thrust.
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Old Jul 20, 2016, 01:14 PM
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No problem with either of my S-3 Vikings, 70mm and 90mm.
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Old Jul 21, 2016, 10:21 AM
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Quote:
Originally Posted by 4stripes View Post
I've never noticed any effect during flight flying twins or singles. ME262, A10,SU34,B737 are some of the models. It isn't worth buying opposite direction fans IMHO.
May be you are right! But you should notice the rotor of MultiRotor.

The fan just have a shroud to limited the blades and getting small(but the RMP is high).

Most time that just be ignore. EDF F35 jet would notice the effect.

At your Me262 and other jet, you just using your controller to change the small difference so not have any effect and it could ignore.

Both are OK,but I like difference direction twin fan.
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Old Jul 22, 2016, 02:58 AM
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Large full size turbofan aircraft have their fans turning in the same direction and there is no "critical engine" (unlike prop driven aircraft).
Food for thought...
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Old Jul 22, 2016, 10:15 AM
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Quote:
Originally Posted by 4stripes View Post
Large full size turbofan aircraft have their fans turning in the same direction and there is no "critical engine" (unlike prop driven aircraft).
Food for thought...
Do turbofans have all the individual fans in the compression part rotate in the same direction? They might be spinning in different directions to negate the effect in each turbine,

Also a turbofan is different than an EDF.
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Old Jul 22, 2016, 03:22 PM
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Quote:
Originally Posted by 4stripes View Post
I've never noticed any effect during flight flying twins or singles. ME262, A10,SU34,B737 are some of the models. It isn't worth buying opposite direction fans IMHO.
Absolutely agree 4stripes.
I've never felt any justification for using 'handed' fan units either.
Reliability of both fans is the important factor, as is setting your flight timer accurately to avoid asymmetric "flame-outs"
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Old Jul 22, 2016, 05:17 PM
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The only time I have observed any torque effect from an EDF is when the aircraft was in a vertical position at practically zero forward speed. Then the airframe can begin rolling due to the fan torque but with normal flying attitudes and speeds there is no descernable able effect.

A large turbofan engine produces the vast majority of its thrust from the main N1 fan exactly like an EDF. The turbine section in a turbofan is just powering the fan to rotate with some residual efflux as it exits the motor.

To prevent asymmetric thrust I always try to power both motors with the same voltage. Either the same battery powers both or two batteries are running with a parallel connection. This way both motors will turn the exact same RPM and should there be a weaker pack, the stronger pack will balance the voltage in the end.
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