I noted that Lee Hines suggested that the Wishbone plans might be available from NFFS Plans Service. I checked the catalog of available plans, and it is not listed there. I do have my personal copy of the 1990 Symposium, and I can make a copy of the three view and article of the Wishbone that appear in this book and send it for $4.00 postpaidi (n the USA).

Contact Bob Stalick, NFFS Publications Services <This email address is being protected from spambots. You need JavaScript enabled to view it.>

F1A in the Wind o remake the timer ?

F1A discussion from the NFFS Forum - FAI Model section.

The National Free Flight Society Forum Index
FAI Models & Flying



Subject Electronic F1A straight tow
 
Original post by Jim Parker



At the NATs last week, Dave Edmonson asked if the Black Magic timer had the capability to support a kiting - straight tow bunt.

[Editorial comment - Clearly the modern F1A can be towed forward directly into the wind and subsequently optionally circled and then bunt launch. What Dave Edmonson wanted to do was have an additional option that would let the model straight tow for a user selectable predetermined time, typically about 30 seconds, and at different, probably reduced decalage. Dave's idea is that would let the flyer charge up wind, aided by the reduced decelage, get out of everyone's way, and then circle tow as usual and launch normally.

I get many requests to change or add features to Black Magic Timers. In this case it did not seem to me to be the best thing to do at this time with my limited resources, I asked some other F1A flyers what they thought and they suggested other approaches that would be better and the disadvanages would out weigh any advantage. For that reason I decided not to do the change at this time. - Jim was involved in some of the discussion and wrote it up for the NFFS forum]

While I'm not big on staright towing, the best flyers in the world at the last WC in the Ukraine in windy, turbulaent conditions demonstarted the ablity to kite- circle tow- bunt. This is my goal, to be as good in difficult conditions.

The problem solver in me got me to thinking on the airline trip home. Here's a
solution, however it does require a mechanical hook modification but it does use
the current Black Magic capablity.

One could put a lever-plunger / spring mechanism that would hold the hook back just
enough to have the hook forward switch open. This spring force would be just
strong enough to keep it back when the model is kited. By using the small micro
switch, this hook back position would be small, in the .060 inch range. A straight
tow rudder hard stop at the rudder with a "stretching rudder line would be need
too to allow the hook to come full forward when the plunger spring force is exceeded.

Now the Black Magic in the F1A mode has three tow - launch settings at the bottom of
the GUI: "circle tow", "straight" and "launch". The "circle tow" setting now becomes
the "kiting" position! When the sportman pulled hard enough to override the plunder
spring force, the fwd hook switch would close moving the stab to the "straight"
tow position-- increasing the incidence for the big pull- bunt etc. This straight
tow stab position does not need to go full incidence because the third Black Magic
setting, "Launch", will give the maxstab up at hook unlatch.

So Dave, there's one idea. Perhaps others can think of a way to do this w/o the
mechanical modification.

Thermals, JIM
 

   
Reply - Dave Edmonson

Post subject: Black Magic Programming      

I see several problems with the Black Magic timer in conjunction with the M&K
style towhook.

Both are really downers and make the not so experienced look really dumb. Actually
I have seen you almost tow into the ground many times, but you are obviously
better at recovering than I am.

This towing into the ground should NEVER happen with a proper control system.

The other straight tow feature is to keep the model from going to the top of
the line when you want to get away from the flight line. This invariably happens
when you inadvertently launch into very good air and you find your model at
the top of the line and you can neither get rid of it, or go to circle mode
without tangling lines.

I need to program the model to fly the way I, I , I want to. If this means
using someone elses timer, then that is what I will do.

I don't want to add any more mechanical complexity to these models, but just to
have them reliably do what they should do. The Black Magic timer has the capability,
but without access to the program, it will only do what they currently do,
and never to be improved.

Thanks for the thoughts!
_________________
Dave Edmonson, proprietor



   
Post by CHE

Post subject:     I love the comment "This towing into the ground should NEVER
happen with a proper
control system", it really made me laugh. Sadly turbulence never knows you
have a proper control system on board when it hits your model.

Guess the idea here is to be able to achieve a bunt launch from a kitting
position without going into a circle, right ? This would be a good idea as
the way I have things set up I typically need to go 'up and off' or do a
circle. Jim's idea seems a possible solution.

But towing in strong wind isn't too difficult (come to the UK and you'll
have lots of practice !) and you get used to seeing the down in front of
the lift. The down can drop the model to 1/2 line height and is followed
by a suddern acceleration as the lift appears. With practice you can time
your launch run just as the model starts to accelerate and hit the lift
perfectly. No changes are needes to the timer setup to do this. Flying
with my new windy weather model with a thicker, lower cambered section
helps a lot and this is where building your own model and following your
own design ideas really can benefit.

Of course it all takes practice but after over 30 years I may finally
getting the hang of it.
 
   
   
Reply by Dave Edmonson
I am glad that you don't understand the situation.

When circling in a wind, and you run out of line, and the model is diving into the
ground, the tow hook is in the forward position. Sometimes you can get it to go
to the circle position by yanking on the line. Other times it looks futile,
and you just let go of the line and go to your second attempt.

Then there is the really bad situation when the model dives so fast that the
hook releases and you bunt straight into the ground.

Both of these conditions are obviously not something that you want to happen.

So you can say that the pilot is doing something wrong like not having enough
line on the ground at the start of the circle or something else. But if it
is only a problem with me, then why do I see all pilots with the same problem?

I say these are problems that people have just accepted as the norm instead
of coming up with solutions. Most of the time the current M/K tow hook design
 will work. It is when the wind picks up that it gets problematic.

Now the straight tow thing, I was not advocating launching with no circle tow
capability. I was saying that I want to be able to run upwind for a given
amount of time before I begin circle tow. This is to get away from line
tangling traffic. In big contests both here and the World Champs, there
s a lot of congestion, and unless you can get upwind, you have a high
likely hood of getting a tangle.
_________________
Dave Edmonson, proprietor
 

   
Replay by CHE


In response to Dave, I see he is looking for a couple of things :-

1) The ability to circle in stong wind without crashing the model
or having to release the line.

2) The ability to run upwind before circling.

Whether you have an M&K or other hook it makes little difference I
would suggest. The problem with 1) strong wind is that often it is
associated with turbulence and not smooth air and it is this turbulence
that makes life difficult for even experinecd fliers. At places like
Livno and Lost Hills there really is no problem in circling in wind
up to the limit. At Barkston Heath (UK site) there are places where
the turbulence is so bad that it is almost impossible to fly in
15mph winds. Changing the hook or timer software will not make the
difference. In my opinion you maybe need a shorter span model with
a dragier (spell) wing and lots of practice and this will alleviate
if not totally solve the problem.

I don't see the problem with item 2). I would suggest this is quite
easy to do. OK, so when it gets windy it is more difficult but certainly
not impossible. With elelctronic timers it is very easy to adjust
the amount of decaledge to help. I'd like to understand better why
this is a problem please.

For both cases it helps to be fit of course. You need to be fleet of
foot, fast in reacting and have good concentration when/if the model
is upset and I'm sure we'll all crashed models or had to release
the line when we've got it wrong.

Not sure, Dave, why you were "gald" I didn't understand you points.
I'm happy to help which is why I'm contributing to the discussion.


         
Reply by DaveEdmonson

 
The GLAD part was if others understood, they would probably have come up with
a solution, and have superior models.

I want to set my model for a stab down position for a pre-determined amount of time,
say 30 seconds to 3 minutes, so that I can straight tow upwind away from the herd.

I don't think circle towing much matters whether you have a short wing or long wing
model in the wind as long as the model wants to circle. When the wind gust
hits you when you are trying to circle, and the tow hook sticks in the forward
position because of tension on the line, you are in a battle to bring it around.

I think a better control system will solve both of those problems.
_________________
Dave Edmonson, proprietor
          


Post by sidewayskid


It seems that over the years as problems with our models evolved, so then have
the solutions. The two driving factors that solve probems are
desire for competitive edge and now, money.
Past problems and solutions............

DT Fuse - clockwork timer Straight tow no lift -
circle tow Wing failure when circle towing - carbon wings

When enough people view the situation as a problem or when need meets enginerring
with an outlook for sufficent profit ,the problem will be solved.
In the mean time, partial solutions are in practice. Last season particular
attention was paid to this as I had more than my share of this experience.

Timing Vasily, taking his model upwind for 1/4 mile and one circle for launch
was witnessed on two occasions on separate days. Parker has also been seen
walking the airborn dog on more than one occasion. Adjustments and practice?
Prior to leaving Taft for Canada and the WC, Peter Allnutt desgined and
built a model specifically for high wind and turbulant conditions. It turned
on a dime in circle mode. The wings were very short, two meters. Watching
flight here, problem sovled. Unsure how it worked in WC conditions.

So, if the "system" is designed that will solve the problem, I may be a
customer. Until then, every effort will be made to clean up my technique
and attempt to copy Peter's model.
Attemptng to grasp the situation,
Mike
     

        
Post by CHE

 
sidewayskid,

I think you have described the matter very well. I feel there is a assumption
with bought models that they will and can do anything you want them to do;
the same with the mechanics and electronics.

In strong wind conditions you need a different type of model compared to
the calm, set up and practiced with appropriately. For UK (and Odessa !)
conditions I built a short span model with lower camber wind section and
it flies well in those conditions. I can walk it like a dog (in fact
better than our dog) forward of the line and circle it up to the
wind limit. The same isn't true of my longer models - they simply
don't work as well. I have had e-mails from Findhal who says
the same thing (my ideas were based on his) so the position is clear.

Incidentaly, I think Allnutt beat me in Odessa by a few seconds. Old age
and cunning wins again !

My short span model has been published so anyone can build it if
they want. I might even build a few for sale but to be honest its
more fun building one than working the hours to buy one.


        
Post by DaveEdmonson

Well I have that model that Vasily towed 1/4 mile upwind. It is a Buntbone with yellow wing tips.

So here is my observation after flying that model that has won 2 World cup meets:
Kharkov, and Sierra Cup, 2006

It flys very nicely.
In the wind conditions that Vasi was flying in, it would tow straight.
But in windier conditions, it goes to the top, and when trying to circle with
lack of line, it will dive like all of the rest.

This is a short model, and the Buntbone design is identical in wing and stab
planform to the Osprey that Hugh Langevin flew so elegantly in the wind.
Almost the same airfoil. In identical launch heights in still air, they
have the same still air time.

Where do I find the plans for the "CHE" model? Or Peter Allnut's design?
_________________
Dave Edmonson



        
Post by flydean
 
This debate sounds like we have been there before, but a long time ago. When
I was a kid, I read extensively what Gerald Ritz wrote concerning glider
design for windy vs. calm conditions.

For calm conditions, his World Champion-winning "Continental" had looong
skinny wings, an almost flat dihedral angle in the main panels and sharply
raised wing tips, a highly undercambered airfoil, and a very, very small
horizontal stab. For windy weather, he had a shorter, tapered wing, less
camber, and larger stab as a percentage of the wing. It also featured
straight "Vee" dihedral.

These were all straight tow models, using conventional DT fuse.

I only saw him fly once, at the King Orange Internats in 1960 down in Miami, Florida.

He flew the Continental mostly, but did a few flights with the windy
weather model, name unknown.
_________________
Dean McGinnes
Lakeland, Florida



         
Post by CHE


 
My design can be found in the 01/07 issue of AMI (Aviation Modeller
International); autographed copies available on request.

So sucessful has this model been in Scottish events that even Bruce Duncan
of that Ilk (a man known to keep Buzzards as pets) is contemplating building
one for those days on the moors when the wind is literally ripping trees
out of the ground.

Can't comment on the Allnutt model other than his history will small
wingspan models is legendary (I think you can even buy built versions
of them from W-Hobby).


Post by sidewayskid

Sorry for the delay in reply........
This new model of Peter's is from a clean sheet. During the hand gliding phase,
an adjustable fuselage was used. Various combinations were tried and detailed
notes made, then converted to graph for comparison.

Peter does not sell his models that I am aware. He will most likely be at the
Sierra Cup and the Livoto. The alternative is to get up in the Winter
at some ungodly hour and track him down in the Taft desert like the rest of us.



    
Post by Jim Farmer

Hi Dave,

Couldn't resist this topic. My first A2 Nordic was a "Poacher". It kited like
a dream, and as Jim Parker can attest, created quite a buzz at a windy team
qualification trials in Albuqurque in or about 1972. The concensus was that
the aft rudder on the Poacher produced the remarkable kiting effect, although
a later similar model with a different airfoil was not even close. Very low
aspect ratio compared to modern F1A's.

One comment about a side effect of Jim P's proposal for the B. Magic system
modified for kiting. I assume nothing prevents the hook from swinging all
the way back if the towline were to go completely slack, placing the rudder i
n circle tow position (considering the hook would still need to swing
back for glide rudder position). Since the circle tow stab setting has
been utilized for kiting, the stab would remain at the reduced angle
position as the rudder goes to circle position, not the typical elevated
circle tow setting, which obviously would cause a problem for a circle
on tow. On the other hand, kiting is something you do in the wind, and
the whole idea as I understand it is to avoid circling and instead
launch straight from a settled back kiting position. So "theoretically"
you would never have a completely slack line. A little risky, but in the
right conditions I'll bet you could get away with it.

About towing upwind, from my limited modern glider experience I have to
agree with the other posters that said no huge problem. I've been able to
walk upwind as far as I want even with my M&K long model on a couple of
very windy days at LH in particular. Yes it definitely goes to the top
of the line and wants to stay there, but it's manageable. And you do
have to circle to launch, but I've managed to occasionally not tow into
the ground by letting the thermal pull the model upwind and having
enough line pulled in (I know you already know this). I think we're
really only talking about windy days here, right, because on milder
days there's no problem towing upwind, sidewind, or anywhere. I've also
thought about experimenting with reduced straight tow stab angle
on windy days, but because of a different motivation. My sons pull
full power no matter what, and really torque the wings on windy
days. Yeah, you tell them not to, see what happens. My thought
was less angle of attack might increase the lifespan of the
wings. I doubt you could take it far enough to allow for a kite-to-launch
scenario since the low stab angle conflicts with the need to a
ccelerate for launch, but maybe worth experimenting with.

Good luck. I've got an extra set of Poacher plans if you want them!
_________________
Jim Farmer
 


        
Post by Bill Shailor

Elton Drew had a rear-mounted fin on his "Lively Lady" model that won the W/C in
1969. On "Happy Hookers" we used to fly, we'd slightly raise the tailplane tow
incidence setting to circle flat in the wind. The towhook would then have to be
moved slightly forward so it would kite.
The good old days!


Post by DaveEdmonson


The thing that I was speaking about is why can't I modify the program to do what I want the model to do?

Does it require a concensus of F1A flyers before the program is
fiddled with by the owner?

I think I will get a friend of mine to write a new program for the
electronic timer so this is no longer a problem.
_________________
Dave Edmonson, proprietor


  
Posted by CHE



 
The question posed is "Does it require a concensus of F1A flyers before the program
is fiddled with by the owner? "

I think the answer is yes. With two different timer systems I have made suggestions on
improvments to the programme to typically add more functionality with flexibility with
no sucess (so far). Part of the problem I believe is that the user (flyer) inteface is
getting much more complex and the producers are concerned that the flyers will start
making more mistakes and blame the timer/programme. I see this problem. I think if
you can find someone to produce a timer to your requirements and then sucessfully
programme it then do so. But this is not a trivial and cheap task. As others have
reiterated, the best way to get what you want, quote "straight tow upwind away
from the herd" is via careful trimming and practice.

CHE


        
Posted by Jim Parker


Dave,

Getting a change made to a "commercially" sold timer is not easy. The firmware is
tightly controlled. For the Black Magic / red Magic, Roger Morrell would not
look kindly into twidling with his firmware. I'd think the other vendors are
the same. I'm not sure it can be done.

I have been using for years (and still i using) a Basic Stamp timer. I could
provide the Ken Bauer schematics and the his basic program. Ken has no
problem with sharing either. This is the Basic Stamp 1-- limited to 80 steps.
I have pushed the limit with a 3 servo, relatching ehook. I was able to
proto type and prove the relatching hook concpt. the advantage is I could
firmware changes to support my fanciful ideas. At that point, Pierre and I
were able to convince Roger to make us two proto type timers based on the
strain gage hook firmware used by Stamov It helps when the timer guy is
in your club.

From this forum string, I do not see the demand for straight tow customization.
Best go the the Basic Stamp or perhaps someone knows of another timer that
supports or allows custom firmware changes?

JIM
 

Comments by Roger Morrell -

Mainly about aspects of the timer and changing. Not necessarily about how to make the model tow better in the wind, in a big contest.

I have read the recent comments with some interest. Firstly let me set something
straight, the decision on what features are put in Magic timers rests with me.
In all cases suggestions from customers and other flyers are welcome and s
ometimes I will go to others and ask them for advice. There is no reason
why I “have to” put any feature in the timer, it just the same saying that
John Clapp “has” to sell rubber that is 5/32” or whatever wide, John will
evaluate and make a business decision. Dave is certainly welcome to go
and develop his own electronic timer.

In every case I need to evaluate all the factors – which include the cost
and feasibility of doing the change, the availability of resources to do
the change, is there something else I’m doing on the timer that is more
beneficial to the users, the number of people who would be interested
and if it would be detrimental to the system as a whole.

Jim is not correct in saying that he has a bit of an advantage because
he and I belong to the same club. I did a special timer for Victor Stamov
and I’ve had discussions with and taken suggestions people in many countries,
including EoB aka CHE [ in writing this I realize that with his beard EoB
does look a little like Che … but I digress !], Paul Lagan, etc…

In the case of what Dave was asking for I decided that I did not want
to do it at this time for a combination of those reasons above. One
of my objectives in making the timers to start with was to help flyers
in general. I understand that it is very difficult for people to get
started and to raise their level of participation. My opinion is that
while this feature may seem to help the beginner it would increase the
complexity and have the opposite effect for the typical beginner, even
though it may be of benefit to Dave.

I find it very interesting that both Ken Bauer and I who are very involved
in the electronic aspects of free flight are very aware of the limitations
and that they play a secondary role to having a good airplane and being
well prepared. At the recent World Champs there was with out doubt circumstance
like Dave wants to address, wind, with poles closer together than they should
be, a record number of flyers and some imaginary barriers that appeared to
restrict the towing space. My contention is that it is living in Sweden,
where the weather is “variable” and flying 3 times a week all year,
including in the wind, together with great models and physical fitness
that got Per Findahl to the number spot, not some electronic trickery.

On a related topic it is important to understand that Magic timers are not
just a timer but a system that comprises 4 major parts, the timer hardware,
the timer firmware or program, the program in the Palm Pilot and the
flight program. I supply the first three and the flyer does the flight
program to suit the model and contest requirements. I take great effort
to make “my” 3 parts work well together and for you to supply your
part as easily and reliably as possible. I have been working on this
for over 15 years and probably have more electronic timers out there
than any one else. Those of you in the systems development business
like me may be aware of the classic text book, The Mythical Man-month
by Frederick Brooks. In this book Brooks states the effort to develop
[which includes end to end testing] a system is 9 times harder than
just a program alone. This means that while a change may appear
relatively simple, it is easy for the cost to extend to several
thousand dollars.

A number of people have asked me for access to the source code of various
components. I will not make this available as I’m not prepared to support
or help any one making and changes as I just do not have the time.
I have enough trouble with people who make “simple” modifications to the
hardware, by “only” changing the size or spacing of the connecting pins
and ending up by breaking the timer and wanting me to fix it. In addition
I believe that inside my software I use some techniques that make my
timers better than others on the market. This does not mean that I’m
not willing to talk about the timers and the functionality. Clearly
there are many ideas about what the timers can or could do and I’m
always ready to talk about that and share ideas with people.

What I have considered is offering a timer development environment,
similar to some that are used for developing simple robots, where a
number of higher level software building blocks could be used
to “build” a timer closer to what someone wanted but still retain
the reliability and functional integrity that I have in the current
timers. I have not pursued this at the moment because I think the
number of people who would use is it is very limited, the cost
is high and my time better serves the free flight community by
doing a few more things on the current timers.

Finally in summary, towing a model in wind, in traffic is challenging, There
are probably many ways of solving the problem. Squire Allnutt manages it by old age and cunning, I'm certainly willing to help with  ideas, it's just that no one has come to  me with a approach that I'm prepared to invest in.

CH407 and B6356b
From: This email address is being protected from spambots. You need JavaScript enabled to view it.


Wishbone#14,

Leeper's comment on the B-6356B being more "unforgiving" than the CH407 deserves some comment. The CH407 is an airfoil which turbulates the upper boundary layer by the shape of the nose and if the shape is just right it does not need turbulators. The B6356b on the other hand needs tubulators to control the upper surface separation which can jump between two widely different flow patterns and can spin a model in. In practice we find this out from flying. On the CH407, if your nose shape is not quite correct, you can solve the problem with a very small turbulator at 5 to 7%c. On the B6356b on Ike's #14 a turbulator is placed at about 7%c which apparently stabilized the problem for his model. My experience with the B6356b on an F1B indicated that another turbulator was needed at about 30%c and I would guess that a F1A with a higher aspect ratio than #14 would also need another turbulator.

Let's mention turbulators when we talk airfoils.

Regards, Hank