RE: [RCSE] Re: Launching Sanity

[mike]

Why must people take these simple ideas and suggest that the result might end up at an unacceptable level?
 
John, "6 Volt Launch Heights" ???
 
When we talk about balancing winch torque with a #300 lb line, I am pretty sure we are outside of the 6 volt launch realm...
 
Darwin, Chico, and Rick won't have any 'splainin to do Lucy..
 
Mike
 Original Message Subject: Re: [RCSE] Re: Launching SanityFrom: John Erickson <[EMAIL PROTECTED]>Date: Sun, December 23, 2007 2:34 pmTo: dharban <[EMAIL PROTECTED]>, Soaring ListOr the set up at Visalia. Very few line breaks considering how manylaunches they go through on a weekend.All this resistance talk is good from a technical point of view, but for theguys at the Southwest Classic they may have a marketing issue on theirhands. "Travel hundreds of miles, spend money staying here and look forwardto 6v launch heights. Guaranteed fewer line breaks".I hope Chico and company have a good welcoming speech! I'm consideringtaking along a smaller plane that might launch higher.JE--Erickson ArchitectsJohn R. Erickson, AIA> From: dharban > Organization: RCGroups.com> Date: Sat, 22 Dec 2007 18:19:00 -0600> To: soaring@airage.com> Subject: [RCSE] Re: Launching Sanity> > > One other thought. The winch setup at the Nats was excellent with> regard to reliability and uniformity. In addition, I did not find the> winches so powerful that they blew my hair back (at least what's left> of it).Perhaps someone who was responsible for the set up of these> winches would like to comment on the setup and what went into setting> them up.> > Don> > > -- > dharban> > dharban's Profile: http://www.rcgroups.com/forums/member.php?u=31927> View this thread: http://www.rcgroups.com/forums/showthread.php?t=789230> > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and> "unsubscribe" requests to soaring-request@airage.com. Please note that> subscribe and unsubscribe messages must be sent in text only format with MIME> turned off. Email sent from web based email such as Hotmail and AOL are> generally NOT in text formatRCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to soaring-request@airage.com. Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
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Re: [RCSE] Re: Launching Sanity

[rmong]

Don,

I noticed at the beginning of unlimited that almost all of
the line was off the drum, therefore we were launching with
approx a 2" dia. drum - was much more easy to control and
modulate the launch.

On a related note, the previous years' masters advertised
"short lines" - ( read larger drum dia. ) I wonder if this,
coupled with the high winds lead to some of the carnage .

Ron Mong


- Original Message - 
From: "dharban" <[EMAIL PROTECTED]>

To: 
Sent: Saturday, December 22, 2007 7:19 PM
Subject: [RCSE] Re: Launching Sanity




One other thought.  The winch setup at the Nats was excellent with
regard to reliability and uniformity.  In addition, I did not find the
winches so powerful that they blew my hair back (at least what's left
of it).Perhaps someone who was responsible for the set up of these
winches would like to comment on the setup and what went into setting
them up.

Don


--
dharban

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Re: [RCSE] RE- NZ

[Lenny970]

 
In a message dated 12/23/2007 2:10:55 P.M. Mountain Standard Time,  
[EMAIL PROTECTED] writes:

Now where is NZ???
Jow moved to NZ = ???
Please tell
Al



Northern Zimbabwe ;-)



**See AOL's top rated recipes 
(http://food.aol.com/top-rated-recipes?NCID=aoltop000304)

Re: [RCSE] Re: Launching Sanity

[Darwin N. Barrie]

We are not locked into the limited winches. Rick is making some and we will 
test them.  I don't think you'll get a reduced launch, you'll  just have to 
do right.


Yesterday we ran 400lb line with a 300lb (half the length) leader. We 
launched everything from Perfects to 2 meters with great success.


With a light head wind I did a couple of full pedal type launches and a 
couple tap ups with full pedal zooms. I was unable to stall the winch.


Trust me, if it won't launch my plane, it will be changed:))

DArwin
- Original Message - 
From: "John Erickson" <[EMAIL PROTECTED]>
To: "dharban" <[EMAIL PROTECTED]>; "Soaring List" 


Sent: Sunday, December 23, 2007 2:34 PM
Subject: Re: [RCSE] Re: Launching Sanity



Or the set up at Visalia.  Very few line breaks considering how many
launches they go through on a weekend.

All this resistance talk is good from a technical point of view, but for 
the

guys at the Southwest Classic they may have a marketing issue on their
hands.  "Travel hundreds of miles, spend money staying here and look 
forward

to 6v launch heights.  Guaranteed fewer line breaks".

I hope Chico and company have a good welcoming speech!  I'm considering
taking along a smaller plane that might launch higher.

JE
--
Erickson Architects
John R. Erickson, AIA



From: dharban <[EMAIL PROTECTED]>
Organization: RCGroups.com
Date: Sat, 22 Dec 2007 18:19:00 -0600
To: soaring@airage.com
Subject: [RCSE] Re: Launching Sanity


One other thought.  The winch setup at the Nats was excellent with
regard to reliability and uniformity.  In addition, I did not find the
winches so powerful that they blew my hair back (at least what's left
of it).Perhaps someone who was responsible for the set up of these
winches would like to comment on the setup and what went into setting
them up.

Don


--
dharban

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Re: [RCSE] Re: Launching Sanity

[John Erickson]

Or the set up at Visalia.  Very few line breaks considering how many
launches they go through on a weekend.

All this resistance talk is good from a technical point of view, but for the
guys at the Southwest Classic they may have a marketing issue on their
hands.  "Travel hundreds of miles, spend money staying here and look forward
to 6v launch heights.  Guaranteed fewer line breaks".

I hope Chico and company have a good welcoming speech!  I'm considering
taking along a smaller plane that might launch higher.

JE
--
Erickson Architects
John R. Erickson, AIA


> From: dharban <[EMAIL PROTECTED]>
> Organization: RCGroups.com
> Date: Sat, 22 Dec 2007 18:19:00 -0600
> To: soaring@airage.com
> Subject: [RCSE] Re: Launching Sanity
> 
> 
> One other thought.  The winch setup at the Nats was excellent with
> regard to reliability and uniformity.  In addition, I did not find the
> winches so powerful that they blew my hair back (at least what's left
> of it).Perhaps someone who was responsible for the set up of these
> winches would like to comment on the setup and what went into setting
> them up.
> 
> Don
> 
> 
> -- 
> dharban
> 
> dharban's Profile: http://www.rcgroups.com/forums/member.php?u=31927
> View this thread: http://www.rcgroups.com/forums/showthread.php?t=789230
> 
> RCSE-List facilities provided by Model Airplane News.  Send "subscribe" and
> "unsubscribe" requests to [EMAIL PROTECTED]  Please note that
> subscribe and unsubscribe messages must be sent in text only format with MIME
> turned off.  Email sent from web based email such as Hotmail and AOL are
> generally NOT in text format

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Re: [RCSE] Launching Sanity

[Mike Lachowski]

Wow, I have my own land now.   Cool...

I have no idea who came up with the idea of using a threaded rod.  But I 
always liked when everyone else used them since while a threaded rod is 
easy to adjust, it's the poorest at getting rid of the heat generated.  
Flat sheets are nicer.  And stainless resistance goes up as temp goes 
up. Constantan or Manganin work much better for resistor material 
since they change very little with temp change.  But they aren't cheap.



Most commonly used adjustable resistors use multiple small rods.

[EMAIL PROTECTED] wrote:

I think Dennis Phelan, of Mike Lachowski Land, deserves the credit for the S/S 
threaded resistor rod rod for use with the FLS Motors.

At least I got my first one from Dennis when he graduated to a F3B specific 
winch.


  


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[RCSE] Re: Winch/Sharon

[dharban]

Both sides are partially correct in this discussion.  What's being left
out is a discussion of what is attached to the winch.

First, the smaller the drum the greater the potential for mechanical
advantage.  At any given level of motor torque, a 1/2" radius drum will
have the capability to develop twice the line pull of a 1" radius drum.

Notwithstanding how much torque the motor can generate, however, the
force of the line to the drum cannot exceed the force of the plane plus
parasitic drag (grass, humps, turnarounds, retrievers etc.) in the
opposite direction.  Therefore, even if the motor/drum combination has
the capability to pull at some level (let's say 200#), if the lift/drag
vector of the glider on the line plus the parasitic drag is only 50# the
motor/drum will only see 50# (I know this an oversimplification, but is
is approximately right for this discussion).  If you sit in a parked
car and stick your hand out the window on a windless day there will be
no aerodynamic force exerted on your hand.  As you move the car faster
and faster, the aerodynamic forces will increase.  The same is true
when you launch your glider.  Notwithstanding the amount of preload
that you crank in with the foot pedal prior to releasing the plane, at
the very moment of release the only force the plane exerts on the line
is the force of inertia required to begin accelerating the plane.  With
no windspeed, there is no aerodynamic force.  This force comes into play
as the plane accelerates and begins to fly.  In this scenario, a small
drum will likely accelerate the plane more slowly than a larger drum
and thus less, rather than more force will be exerted on the plane
until it is fully up to speed.  Therefore it is likely, within some
range depending on the combination of motor torque and speed, a larger
drum will build up force faster than a smaller drum (it is likely that
a 2" drum initially has less ability to utilize the torque available to
accelerate the plane than a larger drum.)

In addition to the relationship of plane speed to pull, you have to
take into account the elasticity of the winch line and the usable
energy it stores as you preload the winch.  If you preload a winch to
some particular force (say 200#) a stronger line will stretch less than
a weaker line -- the energy stored in the stronger line will be released
back to the system over a shorter distance than the weaker line.  In the
most extreme case a steel line with very, very low elasticity will
return its stored energy over a very, very short distance and that
stretch will likely be spent very shortly after the release and not
really useful for acceleration.  The opposite will be true for a very,
very elastic line.  (just ask the F3J guys)  This is the front end of
the effects that result from moving to higher and higher strength
lines.  The back end may be realized when the plane is moving fast
enough to generate aerodynamic forces.  It is possible that some breaks
are the result of less elasticity, in spite of the greater strength of
the line.  It is at least theoretically possible for a plane to build
up aerodynamic forces which, combined with sudden changes of direction
exceed the line strength.  With less elasticity in the line to absorb
the force of the plane's acceleration, the plane's energy is more
immediately and directly transmitted to the line.  This doesn't seem to
happen at the zoom point, but maybe the vectors during the climb
accentuate the possibility of essentially jerking the line apart.


-- 
dharban

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[RCSE] Re: Launching Sanity

[dharban]

One other thought.  The winch setup at the Nats was excellent with
regard to reliability and uniformity.  In addition, I did not find the
winches so powerful that they blew my hair back (at least what's left
of it).Perhaps someone who was responsible for the set up of these
winches would like to comment on the setup and what went into setting
them up.

Don


-- 
dharban

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[RCSE] Re: Launching Sanity

[dharban]

As Darryl Perkins suggested elsewhere, the amount of resistance required
for the FLS will be different from the Bosches that are commonly used in
FAI.  The Bosch is nominally an 1100 Watt motor -- roughly the
equivalent of 1 1/2 horsepower.  According to Injoy, their standard
motor which now replaces the 12V FLS is about 2.4 horsepower -- 1800
Watts.  (and there are claims that it is actually stronger than the old
stock 12V.)  Their souped up replacement for the FLS is about 4
horsepower -- 3000 Watts.

If I understand what the FAI is doing by placing resistors in series
with the motor is to compensate for relatively small differences
between more or less similiar motors.  The basic standard is that the
motor must operate at no more than 1100 watts -- the product of the
current across the motor and the amps through it may not exceed 1100
(watts).  If a stock motor has more has more than 1100 watts input a
resistor is placed in series with the motor.  The added resistance
reduces the current in the circuit and the voltage across the motor to
an amount where the new (reduced) current times the resistance equals
1100.  Thus a motor which is 5% overpowered (1155 watts) when placed in
series with a resistor of approximately .003 ohms would have the product
of the voltage across the motor times the current through the motor
reduced to 1100 watts. (BTW these numbers are based on calculations
which probably oversimplify this explanation -- the illustration is
reasonably accurate in relative terms even if it is not on the money in
absolute terms).  A 1/8" dia steel rod, about 9.5 inches long would
provide adequate resistance and would theoretically be required to
dissipate less than 50 watts.

On the other hand, reducing the stock Injoy motor to 1100 watts would
require a .022 ohm resistor capable of dissipating over 500 watts of
energy.  This would require a 1/8" diameter steel rode nearly 6 feet
long and would have an energy density (watts per foot) nearly twice as
great as the FAI example given earlier -- the rod would get hotter.

Reducing the hopped up Injoy motor to 1100 watts would require a .03
ohm resistor capable of dissipating nearly 2000 watts of energy.  A
1/8" diameter rod nearly 8 1/2 feet long would be required and would
have an energy density nearly 7 times greater than the FAI example --
the rod would get a lot hotter.

Finally, reducing a stock Injoy motor to 1450 watts (half way between a
strong stock FLS and an FAI motor would require a .01 ohm resistor
capable of dissipating around 200 watts of energy.  A 1/8" diameter rod
about 2 1/2 feet long would have an energy density, again, about twice
as great as the FAI example.

At the very least it seems reasonable and feasible to tame the stock
12V FLS if people want to do it.  Taming the souped up Injoy might be
interesting to see (perhaps it will generate its own thermals :) .

Finally, I have flown 8 or 10 flights off of the souped up Injoy (4 hp)
with 300 lb line with a Supra Carbon Light.  It's certainly not beyond
the skills of most competition pilots to launch with this rig, but you
better not screw up the timing between the tensioning and the toss.  It
is wicked strong.  There is no doubt in my mind that it will not allow
near the range of inattentiveness that a stock FLS will for someone
launching an AVA and God help the nostalgia guy that doesn't really
know his stuff when he steps up to this baby.  In addition to the
incrementally increased skill required to use this winch, there is
little doubt in my mind that the strength of the plane being launched
will be more material to the difference in ultimate launch height than
current winches(can you spell universal carbon wings?).  

Its fine if everybody likes the stock 12V FLS, or even if the 4 hp
Injoy becomes the new gold standard.  But what do you think it would be
like when someone comes up with a 6 or 8 hp winch with 450# line?  It's
got to stop somewhere.  Think about it :) 

Don


-- 
dharban

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Re: [RCSE] Re: Post curing West System 105/206

[Jimmy]

Does anyone know where to find R&G products in the US?  Their epoxy is
very good for building composite aircraft.  Lots of information on the
website: http://www.r-g.de/en/

As for whether or not curing will enhance the properties of any given 
epoxy, it would be easy and fast to do a test on identical samples where 
one is cured with heat and one is not.


Jimmy

[EMAIL PROTECTED] wrote:
Are you completely set on using West? As I recall (although I don't recall where 
the numberrs come from) West System doesn't develop properties with post 
curing as nice as some other epoxies. For instance, I have an epoxy mix picked 
up from a boatbuilder I know which has a considerably higher glass transition 
temperature after post cure. ( but again, it's been so long I don't recall exactly 
what those properties or cure temps are). 

For a small job like this, I'd probably use Phase Two from an outfit called System 
Three. You will get a paper telling you exactly how to postcure it. (Two hours at 
140F, but it has to be that warm all the way through). An unusual property is 
that it becomes relatively opaque because of the two phases, which are 
supposed to make it tougher than a singly phase epoxy. Not sure if this works 
in terms of strength and toughness, but it handles ok. Heat deflection temp 
claimed as 64C (147F)


For a big job I'd go back to that boatbuilder I know or else look into Raka as 
mentioned below. 

If I thought the volume was going to be pretty high I'd definitely look into 
prepregs. Probably save a lot of labor and get better properties too, although I 
haven't played with prepregs yet. Your oven might not be enough for them, 
though.


I seem to recall MGS (sp?) epoxies are made for postcure as well.

You might try Raka. The proprieter is willing to talk to you on the phone, and 
can recommend temperatures etc. for various epoxies he has. 

If you pick the right materials and cure it right, you can use colors other than 
white, although I certainly wouldn't do it with West.


If you must use West, it sounds like 120F for 4 to 8 hours is good. I found it in 
the following newsletter from West:

http://www.westsystem.com/ewmag/18/pdf/tanks.pdf
Now, some of that epoxy is mixed slightly different, but not much.
Don't exceed 140F:
http://westsystem.com/webpages/userinfo/moreinfo/coldtemp.htm
(that's a clue that you may not get great thermal properties)

Note that, according to the physical properties on the West site, 105/206 is only 
good for 123F heat deflection temperature. That's why we need to keep it white!


I think, given the labor involved, that if the results are important it's a false 
economy to use the epoxy on hand. Nothing wrong with WEST if you aren't 
going to use the result in high temps or need really high properties in the resin. 
In that case I'd use the ordinary version of RAKA because I've used it with good 
results in the past and it was cheaper.


I realize that you probably have 10X the practical experience laying up glass 
stuff that I have, but I've looked into the post curing thing a little bit.


Even if you stick with WEST, if you get it to 100F overnight it will be reasonably 
well cured overnight. But I understand post curing works best AFTER the initial 
cure.


Bill & Bunny Kuhlman wrote:

Granddaughter Alyssa and I are involved in vacuum bagging processes: 
carbon fiber spar caps, fiberglass over foam flying surfaces, and a 
molded all glass fuselage pod and boom. 

We're using West System 105/206 for all of the components. 

We know that post curing - higher than room temperature heat over 
several hours to a full day - will make the epoxy matrix stronger, 
but after a long web search have been unable to get firm numbers for 
either the temperature required or the recommended time period. 

If anyone can pass on this information, we'd very much appreciate it. 
We have our "hot box" made and can take it up to 160 degrees F. 

Many thanks in advance! 



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[RCSE] RE- NZ

[Albert E. Wedworth]

Now where is NZ???
Jow moved to NZ = ???
Please tell
Al



In a time of deceit 
telling the truth is a 
revolutionary act.
-George Orwell-

Re: [RCSE] line tension

[James MacLean]

So Chuck,  Tell us how the tension limiter worked and how well it worked. 
What were the good points and problems?  Could such a scheme be used 
effectively today?


Regards,  Jim MacLean 


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