HDTenEightyP/NetNews huggingface dataset:
From: svoboda@rtsg.mot.com (David Svoboda)
Subject: Re: Thermals don't travel at prevailing wind speed
Organization: Motorola Inc., Cellular Infrastructure Group
Date: Tue, 28 Jul 1992 22:44:46 GMT

In article <1992Jul28.042041.926@nntpd.lkg.dec.com> fisher@kay.enet.dec.com (kay::fisher) writes:
|>          <<< Note 3.4 by ::mkfeil@bcrki9 "mkfeil@bcrki9.bnr.ca ()" >>>
|>                       -< Re: More R/C Gliding........ >-
|>
|>In article <1992Jul22.233354.6431@rtsg.mot.com>, svoboda@rtsg.mot.com
|>(David Svoboda) writes:
|>> forth across the region, always turning into the wind.  The thermal moves 
|>> downwind, a little slower than the wind speed.
|>
|>Please explain. How can a thermal bubble move slower than the average
|>speed of the surrounding air mass?
|
|The same way bubbles get to the surface of a river.  If they only
|went down stream they would never come up.  If they come up then
|obviously they aren't going down stream as fast as the rest of the
|river.

Uh, I think that a bubble *does* go as fast --horizontally-- as the
rest of the river.  It's just that the bubble also has a vertical
component, so actually the resultant velocity vector has a larger
magnitude than the actual speed of the water.

Sorry, Max, that I didn't get back to your question; I will now:

I said that it is helpful to *think of a thermal as a bubble*, I
didn't say it *was* a bubble.  A thermal is actually a near vertical
shaft of rising air, which emanates from a particular region of
earth.  It is primarily fixed, at the bottom, althogh not in time
(that is, it has a fairly short duration, and is cyclic).  The
prevailing wind blows the top of the cylinder downwind.  In that
case, for all intents and purposes any particular region inside the 
thermal (which can extend for tens of thousands of feet, and 
intensifies with altitude) can be thought of as a "bubble" of rising 
air, and the glider rides on "top" of the bubble (though we know that 
the glider is really *inside* a velocity vector field).  It seems 
like there are warm air bubbles emanating from the ground periodically, 
but really it's only the velocity vector field intensifying and 
depleting, and only on the very bottom of the thermal.  If you can
get some serious altitude, thermals seem rock steady, and do not move
around.

Simply put, it is a lot easier (for me) to find thermals if I feel
the wind, and the temperature, and picture big bubbles of air rising
from the earth. 

			Dave Svoboda, Palatine, IL
From: bcoleman@hayes.com (Bill Coleman)
Newsgroups: rec.models.rc
Subject: Re: Taildraggers taking off (P-factor & Torque)
Date: 22 Jul 92 17:53:55 GMT
Organization: Hayes Microcomputer Products, Norcross, GA

In article <Brr5K9.MID@usenet.ucs.indiana.edu>, ntaib@silver.ucs.indiana.edu (Iskandar Taib) writes:
> In article <5797.2a6b026a@hayes.com> bcoleman@hayes.com (Bill Coleman) writes:
> 
>>Faugh! Thrust INCREASES in the air. It does not "drop off." What causes
>>the airplane not to accellerate any further is the subsequent increase
>>in DRAG! When the aircraft reaches the speed at which the total drag
>>equals thrust, it ceases to accellerate. That's the cruise speed. 
> 
> It increases up to a point, then it drops off. 

This is because of the vagarities of the output of the motor, not the
prop. Once you get beyond the RPM peak, the total amount of power
from the motor lessens, and the thrust lessens. But it does this very
slowly.

> Which is why you can 
> only go a certain speed with a low pitched prop but can exceed that 
> speed with a higher pitched prop. 

Right, since the same prop induced drag (ie same required torque) is
related to the prop AOA. If the prop has more pitch, that AOA is
reached at a higher speed. If the prop has too much pitch, the total
drag halts the aircraft accelleration long before the optimum AOA is
reached.

> Which is why one often can't have
> unlimited vertical climb even if static thrust exceeds weight.

Huh? I don't see how this is related to propeller performance.
You can't change the laws of physics. In a vertical orientation,
the primary forces acting on a plane are thrust, weight and DRAG.

Even if thrust exceeds weight, you still have to have extra thrust to
compensate drag. If thrust exceeds the sum of weight and drag, the
aircraft will accellerate upward. If thrust is equal to that sum,
the aircraft will continue upward at the same speed. (For the limited
heights used by model aircraft, this would result in an "unlimited"
vertical climb)

> Which is why props can act as brakes in a dive.

Props act as brakes in a dive because you are changing the angle of
attack. As you move the plane faster than the prop, the AOA decreases,
hence the induced drag decreases and the torque required decreases,
so the prop spins faster. At some point, the engine can't spin any
faster since the torque output decreases faster than the requirements.

At this point, the engine resists further rotation. Even if the props
are at a highly negative AOA (which results in a forward (spinward)
pointing induced drag component), the engine can't turn any faster.

-- 
Bill Coleman, AA4LR                ! CIS: 76067,2327    AppleLink: D1958
Principal Software Engineer        ! Packet Radio: AA4LR @ W4QO
Hayes Microcomputer Products, Inc. ! UUCP: uunet!hayes!bcoleman
POB 105203 Atlanta, GA 30348 USA   ! Internet: bcoleman%hayes@uunet.uu.net
Disclaimer: "My employer doesn't pay me to have opinions."
Quote: "The same light shines on vineyards that makes deserts." -Steve Hackett.
From: shane@peeker.uucp (Shane R. McCarthy)
Newsgroups: rec.models.rc
Subject: Re: magazine index
Date: 24 Jul 1992 22:07:06 GMT
Organization: Not an Organization
X-NewsSoftware: GRn 1.16e (7/4/92) by Mike Schwartz & Michael B. Smith

In article <1992Jul24.182130.13484@cbfsb.cb.att.com> jck2@cbnewsg.cb.att.com (john.c.kelly) writes:
> I'm sure someone with more time than I have has created an ASCII 
> file of the topics covered in my favorite R/C rags.  Does anyone out
> there know how I can contact that person?  Has anyone used such an
> index?  
> 
> If no one has created one maybe we can collectively create one.


   I was pondering the same question.  My interest is in planes thou.
Anyone out there come across an index in ASCII for R/C planes.



-- 
Shane McCarthy                  Please forward mail to
Windsor, Ont.                   stss.org!jabba!peeker!shane
Newsgroups: rec.models.rc
From: bobwo@ecs.comm.mot.com (Bob Woodhouse)
Subject: Re: tweaking stock motors
Organization: secure_comm
Date: Tue, 21 Jul 1992 11:11:51 GMT

In article <1992Jul20.212412.29457@usceast.cs.scarolina.edu> hutto@smtc.engr.scarolina.edu writes:
>In article <richard.711657035@tdsb-s>, richard@mais.hydro.qc.ca (Richard Patenaude) writes:
>>At the club i race, we can only use stock speedwork motors (Dirt Oval), my 
>>problem is that all the A main racers know how to get more RPM's out of their 
>>motors without opening the can....does anyone out there know how to do it and 
>>would be nice enough to tell me?
>>
>>
>>                                   Tired of being blown away!!!!!
>>
>>                                             Richard
>
>    I don't know very much about juicing up "stock" motors since I don't 
>    race in any "stock" classes.  I race because I like racing, not because
>    I like messing around with motors, so "modified" classes are a better
>    deal for me.  That said, here's what little I do know about motor tweaks.
>
>    There are three basic approaches to making a stock or handout motor
>    produce more power.
>
>
>-------------------------------
>Brent Hutto
>hutto@SMTC.engr.scarolina.edu


I read in the most recent R/C Car Action about one stock race where the
winning car had used metal polish compound between the armature shaft
and the bushing, which allegedly made the bushing hole slightly larger
(go figure the advantage in that) and made for a nice polished meeting
of the metals (perhaps a more clear advantage).  I do not race stock
either, so I can only offer this. 

By the way, I frequently hear the stock drivers at the track I have been using
talk about all the questionable mods they have made to their stock motors.

Good luck,
Bob Woodhouse 
Newsgroups: rec.models.rc
From: simon.s.huang@hydro.on.ca ()
Subject: 4-Stroke and Scale Rally
Organization: Ontario Hydro
Distribution: ont
Date: Thu, 23 Jul 1992 15:43:18 GMT

The Radio Control Flying Club of Toronto is hosting the 8th Annual
4-Stroke and Scale Rally Aug 15-16 1992. 
Location:

Miliken Park ( Macowan and Steeles) 
Newsgroups: rec.models.rc
From: djones@iex.iex.com
Subject: Re: Props
Organization: IEX Corporation Inc.
Date: Thu, 30 Jul 1992 22:06:00 GMT

In article <1992Jul28.230434.26635@rtsg.mot.com> svoboda@rtsg.mot.com (David
Svoboda) writes:
>Prop load is prop load.  I would use it in any case.
>
Makes sense.

>A 11x6 prop would be similar in engine loading to a 10x8.  That is, you would
>realize approximately the same engine rpm *at a given airspeed*.  Now,
remember
>that a lower pitch will give you a lower airspeed, but more static thrust. 
Think
>of it as a "lower gear".  Thus, a low pitched large diameter prop is good for
>a naturally slow airplane, and will give you a good climb.  A higher pitch
prop
>will have less climb or acceleration, but will pull the airplane with a faster
>top speed (and a faster cruise speed, for that matter).  If you are
underpowered, 
>a larger, lower pitch propeller would be a better use of the engine's
horsepower, 
>but you have to limit that becuase that airplane will have a minimum speed,
and 
>an extremely low pitched prop would not pull it faster than that (stall on
takeoff).
>
Also makes sense. I have also been the victim of this!

>A higher loading prop will lug the engine, which makes the mixture very hard
to
>adjust.  You can easily have a lean run, and have it masked.
>
Oh Boy! Sounds like a trashed 4 c if a guy ain't careful!

>I'm not any sort of 4-stroke guru (well, with motorcycles, maybe, but not
model
>airplanes :-), but that sounds like a good method of protecting your engine. 
I
>would further suggest that you peak the engine with the nose pointed at the
>sky, rather than level.  And listen and look at it flying--some engine just
seem
>to change mixture in the air when they unload.
>
I will and I do. Except when the unmuffled gas burners are flying!

>
>Sure there is.  Try an alternative, and see if it works.
>
I did. I bought a bigger engine! A wimpy way out of the problem
but on our field there is very little room for error. Our asphalt runway is
about 300' feet long but is only 20 - 25' wide. It has a maze field on two
sides 
and a fence on one. I love scale, but am not confident enough to sweat
out the take-off's! So I took the easy way out and sold the 40 Surpass
and bought a 48 Surpass.

Thanks for your help!
Doug

PS 
There is a very good article on props in the August Model Builder.

-------------------------------------------------------------------
'I am a traveler of                |    Douglas R. Jones
     both Time and Space'          |    IEX Corporation
       Led Zeppelin                |    (214)612-2600 ext: 325
                                   |    djones@iex.iex.com
                                   |    uunet!iex!djones
-------------------------------------------------------------------

Newsgroups: rec.models.rc,sci.electronics
From: amg@cbnewsh.cb.att.com (alan.m.gopin)
Newsgroups: rec.models.rc
Subject: Re: tweaking stock motors
Date: 21 Jul 92 13:50:37 GMT
Article-I.D.: cbnewsh.1992Jul21.135037.25744
Organization: AT&T

From article <richard.711657035@tdsb-s>, by richard@mais.hydro.qc.ca (Richard Patenaude):
> At the club i race, we can only use stock speedwork motors (Dirt Oval), my problem is that all the A main racers know how to get more RPM's out of their motors without opening the can....does anyone out there know how to do it and would be nice enough to tell me?
> 
> 
>                                    Tired of being blown away!!!!!
> 
>                                              Richard

If you are really serious about this, the first thing you need to
do is to get access to a dyno. That will give you the measuring
tool you need to understand the results of any changes you
make. The next thing you need to do is realize that you are
conducting a trial and error scientific experiment. Document what
you do carefully, and do everything possible to keep the test
parameters the same (e.g. voltage, load, etc.). Finally, you need
to try a bunch of changes out and see what gives you the most RPM
and torque. Here are some things to try:

Various brush/spring combinations. Your mileage may vary, but I
have had good luck with stock motors using the Reedy 1/12th scale
competition full brushes with Bud's purple (heavy) springs. You
will also want to see the effects of soldering the brushes
vs. using hook and eye.

Use jeweler's rouge to polish the bushings where they meet the
comm. You can also chuck a new stock motor without springs and
brushes and run it in a dremel tool for a while without
lubrication to break in the bushings.

Get a spring thing and experiment with spring tension.

Get a hood alignment tool and use it.

Use comm sticks on your motor after every run to keep the comm
clean.

Remember, dyno the motor after everything you try. Good Luck.

				Alan Gopin
				
-- 
Alan M. Gopin
AT&T Bell Laboratories
gopin@homxb.ATT.COM
att!homxb!gopin
Newsgroups: rec.models.rc
From: mmcevill@mitre.org (Michael A. McEvilley)
Subject: Re: HELP! Where's Futaba?
Organization: The MITRE Corporation
Date: Tue, 21 Jul 1992 13:20:02 GMT

In article <1992Jul20.144427.27954@informix.com> robertw@informix.com 
(Robert Weinberg) writes:
> Where can I get hold of Futaba?

For info, future reference, whatever:

Futaba Corporation of America
4 Studebaker
Irvine, Ca, 92718
** Call information for the phone # **

And as the other posters mentioned, you should get replacement servo gears 
from a local hobby shop.

Michael
Newsgroups: rec.models.rc,sci.electronics
From: bobwo@ecs.comm.mot.com (Bob Woodhouse)
Subject: Re: How to dispose of NiCads?
Organization: secure_comm
Date: Wed, 29 Jul 1992 14:40:13 GMT


>|>             300 ohm              Charge
>|>                5W             /  Switch 
>|> 20-40 + O---/\/\/\----o------o  o------------o-------------------------o
>|> VDC                   |                      |                         |
>|>                       |      Zap             |                         |
>|>                       |      Switch          |                        +|
>|>                       |      ___|___         |                    -----------
>|>                       o------o     o---------o                       -----
>|>                       |                      | +             Shorted   |
>|>       6000 micro-     | +                 -------             Cell     |
>|>       Farad, 40V  _________               |     |                      |
>|>       Capacitor   ---------               |_____| Volt                 |
>|>                       |                      |    meter                |
>|>                       |                      |                         |
>|>       - O-------------o----------------------o-------------------------o
>|> 
>
>Please correct me if i get this wrong, i guess the above circuit requires
>to remove the dead cell from the multi-cell pack, right ?
>  

Why would you have to remove the cell -- just hook up to the cell of interest and go.

>Which means, one has to take the Ni-Cd pack appart, and get the dead cell out.
>The cells are usually connected with a point welded metal plate, which requires
>you to rip the metal plate off the cell. 
>Now, once you fixed your shorted cell ( you hope ),with the above circuit ,you will have to
>solder the cell back in place, which isn't that abvious, if you apply to much
>heat when soldering you may damage the cell, if you don't apply enough heat you get
>a cold solder spot, in which case it may brake loose, due to vibrations.
>
>-- 
>ben
Bob Woodhouse

Newsgroups: rec.models.rc,sci.electronics
From: lester@naomi.NoSubdomain.NoDomain (Les Bartel)
Subject: Re: How to dispose of NiCads?
Reply-To: lester@naomi.b23b.ingr.com
Organization: Dazix, An Intergraph Company
Date: Wed, 29 Jul 1992 12:42:24 GMT

In article <1992Jul29.084514@ufps9.unifr.ch>, waeber@ufps9.unifr.ch (Bernard Waeber SIUF) writes:
|> In article <p5mmrwq.brunette@netcom.com>, brunette@netcom.com (Hal Brunette) writes:

[Text of 'zapper' deleted]

|> Please correct me if i get this wrong, i guess the above circuit requires
|> to remove the dead cell from the multi-cell pack, right ?

Maybe not, see below.

|> 
|> Which means, one has to take the Ni-Cd pack appart, and get the dead cell out.
|> The cells are usually connected with a point welded metal plate, which requires
|> you to rip the metal plate off the cell. 
|> Now, once you fixed your shorted cell ( you hope ),with the above circuit ,you will have to
|> solder the cell back in place, which isn't that abvious, if you apply to much
|> heat when soldering you may damage the cell, if you don't apply enough heat you get
|> a cold solder spot, in which case it may brake loose, due to vibrations.
|> 
|> The point is : You better know what you're doing, when trying to recover a 
|> 	       dead Ni-Cd cell.

Absolutely.

|> 
|> 	       Guess your plane or heli is worth more, opposed to the 20 bucks
|> 	       for a new Ni-Cd pack.
|> 
|> So, if you aren't too confident of fixing your Ni-Cd pack, return them to the place
|> where you bourght them.
|> 
|> -- 
|> ben

You don't have to remove the cell from the pack (unless it is in parallel
with another cell).  Just clip the zapper leads to the terminals of the
cell.  In fact, it seems to me that it may even work without isolating
the cell if there is a cell in parallel.  The shorted cell should take
most of the current, and the non-shorted cell some current as well.

	 Bad cell
	     |
	     v
   ___      ___      ___
--|___|----|___|----|___|--
         |       |
         |       |
         |       |
         |       |
	zapper leads

 - Les

-- 
Les Bartel			lester@naomi.b23b.ingr.com
Dazix, An Intergraph Company	uunet!ingr!b23b!naomi!lester
Newsgroups: rec.models.rc
From: svoboda@rtsg.mot.com (David Svoboda)
Subject: Re: More R/C Gliding........
Organization: Motorola Inc., Cellular Infrastructure Group
Date: Thu, 23 Jul 1992 15:17:21 GMT

In article <1992Jul23.220857.6043@csc.canterbury.ac.nz> kaiser@elec.canterbury.ac.nz (Chris Kaiser) writes:
|In article <1992Jul22.233354.6431@rtsg.mot.com>, svoboda@rtsg.mot.com (David Svoboda) writes:
|
|> 9. Find a "cruise speed" and a "thermal speed" for your particular airplane, and
|> memorize the elevator trim positions for these.  Cruise speed is usually your
|> best glide ratio; that is, it's when you cover the most ground horizontally, for
|> the amount of altitude you are losing.  This is typically pretty fast.  Thermal
|> speed is your minimum sink rate, usually just a bit faster than stall.
|
|A guy at our club once told me a good tip for setting up a thermal soarer - once
|you've found the cruise position, set up the elevator linkage so that full-down trim
|gives you cruise. It makes it much easier to fly consistently when set like this. For
|thermalling you pull as much up-trim as required for the conditions.

That's good for many planes.  The thing is, my fave thermal soarer was the aforementioned
Sagitta 900, and that airplane was special in that it had a "best cruise" that was fast
enough that control (rud&elev) wasn't very sure, so I preferred to cruise around at a
bit less than that.  Full down trim would produce the unbelievably fast 
"streak-across-the-sky-let's-get-the-heck-OUT-of-there" cruise, and full up trim would 
give a typical minimum sink, and somewhere in between was the "normal" cruise.  I think
that that behavior was due to the "drag bucket" on the Eppeler 305 (?) airfoil used, and
a clean model.

I guess it just depends on your airplane.  And nobody said it was easy.  :-) :-) :-)

		Dave Svoboda, Palatine, IL
Newsgroups: rec.models.rc
From: djones@iex.iex.com
Subject: Aerodrome '92
Organization: IEX Corporation Inc.
Date: Wed, 22 Jul 1992 22:31:04 GMT

Anyone attending Aerodrome '92 on Labor Day weekend?

Doug
-------------------------------------------------------------------
'I am a traveler of                |    Douglas R. Jones
     both Time and Space'          |    IEX Corporation
       Led Zeppelin                |    (214)612-2600 ext: 325
                                   |    djones@iex.iex.com
                                   |    uunet!iex!djones
-------------------------------------------------------------------

Newsgroups: rec.models.rc,sci.electronics
From: sbbrown@magnus.acs.ohio-state.edu (Stephen B. Brown)
Subject: Re: How to dispose of NiCads?
Organization: The Ohio State University Radio Observatory
Date: Mon, 27 Jul 1992 20:47:04 GMT

In article <1992Jul27.161240.4905@nynexst.com> rsilvers@powwow.nynexst.com (Rob Silvers) writes:
>	I have a bunch of NiCad cells that I no longer want.  Should I just
>throw them away?  Is there an established place to bring them?  

Send them back to the manufacturer.
-- 
Steve Brown, N8HFI              sbbrown@magnus.acs.ohio-state.edu
Chief Engineer, The Ohio State University Radio Observatory ("Big Ear")
Newsgroups: rec.models.rc
From: m14494@mwvm.mitre.org (Mike White)
Subject: Re: Hover achieved... with my Glider!
Organization: The MITRE Corporation
Distribution: na
Date: Wed, 22 Jul 1992 14:13:26 GMT

In article <1992Jul22.090149.12274@rice.edu> rusty@masc.rice.edu ( Robert 
Kelley) writes:
>I would like to call the net's attention to the line beginning, "I did 
>have one nasty surprise, though."  This actually translates into about ten 
>lines of mostly uninformative gibberish.  Will whoever this person's sysadmin 
>is either compel it to mend its ways or remove it from the net?  RSK

When I read your response to my post, I thought you
were saying that the message had been corrupted into
"gibberish" of the computer sort.  If so, my previous
response pertains.  If, however, you were commenting
on the *content* of my post, then you should definitely
consider switching to a bran cereal.

************************
* These are my opinions only.*
************************