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Helicopters

02/12/2014 11:53 AM

Sir,

I need some details of helicopters with tail rotor for my project. they are

1. is it required to maintain certain(1:6,1:3, etc)rpm ratios (main rotor rpm to tail rotor rpm) to provide effective anti-torque.

2. instead of keeping rpm ratios mentioned earlier is it enough to have sufficient thrust alone to counteract anti-torque.

3.is the thrust of tail rotor depends on these factors RPM,tail rotor blade area and shape. what are their individual contribution?

4. with minimum rpm in tail rotor is it possible to obtain high thrust for anti-torque.if so how?

5.i m designing a helicopter model with mini compression ignition engine(1.5cc) with rpm upto 16000..what is its hp and torque? to counteract main rotor torque what is the thrust required from the tail rotor(distance of tail rotor shaft to main rotor shaft is 1ft which is fixed)

i need detailed info of above question ......please reply as soon as possible

thank you in advance

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#1

Re: Helicopters

02/12/2014 12:12 PM

Helicopters are very complicated to figure out. Lots of things in play.

Moment arm of the tail rotor must be calculated, this somewhat driven by the main rotor diameter. Main rotor torque to be overcome/balanced will vary as the pitch of the spars varies.

You have quite a bit of cipherin' to do. This is still the easy stuff.

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#2

Re: Helicopters

02/12/2014 12:25 PM

You seem to be having a very common problem. Now that you understand many of the details you seem to need to review the fundamentals.

1) To hold a stationary position all forces must be in balance.

2) To move in a desired manner the balance of forces must be disturbed to provide a force of the necessary direction and magnitude to provide the desired motion.

Fundamentals #1 and #2 apply all the time. They apply for pitch, yaw and roll. They apply if stationary, going up, going down, twisting, rolling or going to the pub for a cold one.

There are various "yes" and "no" answers to your posting. If you come to terms with #1 and #2 I think most of your answers will fall into place easily.

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#3

Re: Helicopters

02/12/2014 12:28 PM

It must be about thrust not ratios otherwise NOTAR helicopters would not be possible.

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#7
In reply to #3

Re: Helicopters

02/12/2014 6:29 PM

Well, yes, but....................it's the ratio of tail rotor, or tail boom fan, thrust that provides the anti-torque energy to keep the nose of the chopper pointed where the pilot wants it be be pointed.

OP, don't worry about NOTAR.

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#4

Re: Helicopters

02/12/2014 12:42 PM

I think a gyroscope for torque and wind stability....but I would get some modeling time under my belt, and study how these systems work....

"The various helicopter controls are effected by means of small servo motors. A piezoelectric gyroscope is typically used on the tail rotor (yaw) control to counter wind and torque reaction induced tail movement. This "gyro" adjusts the control signal to the tail rotor motor or servo."


http://www.microhelicopter.co.uk/

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#5

Re: Helicopters

02/12/2014 1:40 PM

Do your own homework. CR4 is not a homework cheat site. While some here might relish the opportunity to sharpen up old rusty skills by working the homework problem, consider the following and consider it well. If you cheat on your homework by using someone else's answers, you are only cheating yourself, because the purpose of any homework or other academic assignments is to help you learn - by practice, repetition, and self-discovery.

How Do Helicopters Work? | Wonderopolis

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#6

Re: Helicopters

02/12/2014 2:02 PM

this little detail is unimportant on your homework

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#8
In reply to #6

Re: Helicopters

02/12/2014 6:39 PM

This looks a little scale disproportionate to the discussion...

Point is made, but the consequence of failure comparisons vary by an exponent or two.

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#9
In reply to #8

Re: Helicopters

02/12/2014 7:03 PM

Well,

The OP's knowledge level seems very scale disproportionate to his plan to "design" a complex machine.

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#10
In reply to #9

Re: Helicopters

02/12/2014 7:21 PM

Agreed.

Disciplines involved in a successful aircraft design are many.

About 422 years ago I worked for Boeing... Wow, was that both interesting and eye-opening. Learned a lot in a very short time... this is possible if a fella pays attention to advice from those with a little time under their collective belts.

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#11
In reply to #10

Re: Helicopters

02/12/2014 8:47 PM

"Collective". Gotta love that play on words!

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#12
In reply to #11

Re: Helicopters

02/12/2014 9:40 PM

Nice catch! How about the shirt-tail reference here?

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#18
In reply to #12

Re: Helicopters

02/14/2014 12:10 PM

A little lacksadasial don'tcha think? If we ever did a one-hand catch like that, our coach would have chewed our butts. But then again we were just a bunch of snot-nosed kids instead of multi-million dollar professionals.

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#19
In reply to #18

Re: Helicopters

02/14/2014 1:14 PM

Well, yeah, there is that.

The player that basket-caught the ball was the pitcher, who had thrown the pitch then collected the fly ball.

Thus, it could be said he had just thrown a 'Collective Pitch'.

Thank you, thank you... I'll be here all week. Remember to tip your waitress generously, and management wants me to remind you to try the fish.

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#20
In reply to #19

Re: Helicopters

02/14/2014 1:17 PM

Ah, now I get it. Doh !!

Love the pun. Where's Hooker? He'd be all over this thread.

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#21
In reply to #20

Re: Helicopters

02/14/2014 1:27 PM

I thought the same thing about Hooker. Right up his alley.

I am beginning to suppose our wit and wisdom are wasted on sathishvh.

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#22
In reply to #19

Re: Helicopters

02/14/2014 2:29 PM

Ahh, I see.............. I guess we're not all familiar with these local sports.

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#14
In reply to #11

Re: Helicopters

02/13/2014 12:12 AM

Yeah, but those wordplays are cyclical.

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#17
In reply to #14

Re: Helicopters

02/13/2014 9:35 AM

Nice!

I wonder what kind of paint our OP should use on this project...

Hmmmmm... nope, nothing comes to mind.

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#13

Re: Helicopters

02/12/2014 11:08 PM

Try designing it with 2 counter-rotating rotor blades...no tail rotor needed.

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#15
In reply to #13

Re: Helicopters

02/13/2014 12:50 AM

Or a single rotor with jet-engine tips. (Although that's beyond the realm of Thimble Drome tech.)

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#16

Re: Helicopters

02/13/2014 9:25 AM

Buy a kit, build it, fly it and learn.....

At your present state of knowledge, you are never going to build anything that works, other than to empty your wallet......

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