Alt-BEAM Archive
Message #10494
To: beam@sgiblab.sgi.com
From: "Timothy Flytch" flytch@hotmail.com
Date: Sat, 19 Feb 2000 21:15:13 PST
Subject: [alt-beam] Re: BEAM: Tendency toward miniaturization
>You put up a good argument, and the reference to the grail cinches it. I
>still think we've come a little bit farther than most will admit, but
>obviously not nearly far enough.
>
>dennison
>
Your argument reminds me of aviation... The wrights flew in 1903... but
there were a lot of planes build well into the twenties that never got off
the ground because they did not have a clue as far as aerodynamic forces...
My personal favorite was a tri-plane that was made in 1917or so with
penates(little triangular flags) because the builder argued that "flags
fly"...
Just try to imagine what this "BEAM" thing may be in twenty years???
Timothy...
______________________________________________________
10495 Sat, 19 Feb 2000 21:38:01 -0800 [alt-beam] Re: Where's the FAQ? beam@sgiblab.sgi.com Bruce Robinson "D. Michael McIntyre" wrote:
>
> Most of the links in the introductory message are broken.
>
> I want to read the FAQs before I annoy everyone with a bunch of stupid
> questions.
If you are refering to the links to Bushbo's site, there seems to be an
automatic cutout with his ISP that blocks access whenever the monthly
traffic exceeds a maximum. So late in the month, it will appear that the
link is broken. Wait until the first of the month, and you'll find them
working again.
Regards,
Bruce
10496 Sun, 20 Feb 2000 09:49:26 -0500 [alt-beam] Re: solarbotics pager mtr+fan beam@sgiblab.sgi.com Bob Shannon Ahhh, can you list production aircraft with counter-rotating props?
And how many more can you lise with both props rotating in the same
direction?
Timothy Flytch wrote:
> No Dave... they use counter rotating props on modern aircraft to allow
> single engine operation... Trust me I've studied aerodynamics for over
> twenty years...
> if you would like to discuss this feather lets do it off list. ok?
> Timothy...
>
> >At 11:38 PM 2/18/00 , Timothy Flytch wrote:
> >>Only if the axels or coaxial... if you separate the blades then you do not
> >>have to use counter rotating blades to counter act tork... you use an
> >>offset or tilt of the blade disk to counter tork...
> >
> >
> >I disagree. If this were true, then many twin engine aircraft wouldn't be
> >going through so much effort to have props spinning in opposite directions.
> >Engine torque is a (counter)useful tool to turn aircraft in one direction
> >harder than the other.
> >
> >Just like in any other physics system, the sum of the forces must be zero;
> >if there isn't an equal and opposite torque from the motors, it's going to
> >come from with resistance with the surrounding air, and produce rotation
> >effect.
> >
> >-Dave
> >
> >---------------------------------------------------------------
> >"Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
> >that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
> > 2 vowels. Pronounciation? _SMITH_".
> > http://www.solarbotics.com
>
> ______________________________________________________
>
10497 Sun, 20 Feb 2000 09:54:24 -0500 [alt-beam] Re: solarbotics pager mtr+fan beam@sgiblab.sgi.com Bob Shannon Before the thread disappears off line..
If you have a motor out, why does it matter which direction the remaining
prop rotates?
It matters only because the tail of the aircraft has an offset to counteract
the
torque and P factor (gyroscopic precesion). If you have counter rotating
props and loose an engine, you want to know what direction the remaining
torque wants to turn the plane so this may be trimmed out by the tail.
Thats why general avation twin engine aircraft have both motors running in
the SAME direction.
For electric flight, single engine operation is a non-issue, failures are very
rare. But operating one motor in reverse will usually cause a torque
imballance
because motors have a prefered direction of rotation (most often).
Dave Hrynkiw wrote:
> At 08:43 PM 2/19/00 , Timothy Flytch wrote:
> >No Dave... they use counter rotating props on modern aircraft to allow
> >single engine operation... Trust me I've studied aerodynamics for over
> >twenty years...
> >if you would like to discuss this feather lets do it off list. ok?
>
> Ditto, but in an informal sense. Model aircraft enthusiast, started
> Aeronautical engineering, finished in Mechanical.
>
> Counter-rotation indeed does help one-engine-out scenarios, but you simply
> cannot have a "free lunch" when it comes to torque. One or two motors,
> there has to be something counter-acting the force of the prop against the
> air, be it a rudder, offset engine thrustline, or another torque source
> acting in the opposite rotation (ie: 2nd engine reverse rotation).
>
> That said, if you wish to pursue this further, offline it is....
>
> Regards,
> Dave
> ---------------------------------------------------------------
> "Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
> that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
> 2 vowels. Pronounciation? _SMITH_".
> http://www.solarbotics.com
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