Home › Forums › Free Flight › FAI Models & Flying › Electronic F1A straight tow
- This topic has 19 replies, 8 voices, and was last updated 15 years, 6 months ago by Roger Morrell.
08/06/2007 at 8:17 pm #40680AnonymousInactive
At the NATs last week, Dave Edmonson asked if the Black Magic timer had the capability to support a kiting – straight tow bunt.
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, JIM08/07/2007 at 3:23 am #44552AnonymousInactive
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!08/07/2007 at 9:14 am #44553AnonymousInactive
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.08/07/2007 at 11:42 am #44554AnonymousInactive
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 is a lot of congestion, and unless you can get upwind, you have a high likely hood of getting a tangle.
08/07/2007 at 12:50 pm #44555AnonymousInactive
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.08/07/2007 at 5:52 pm #44556AnonymousInactive
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.08/13/2007 at 2:02 am #44557MIKE SZURAParticipant
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,
Mike08/13/2007 at 9:11 am #44558AnonymousInactive
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.08/13/2007 at 4:28 pm #44559AnonymousInactive
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?08/13/2007 at 4:54 pm #44560Dean McGinnesParticipant
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.08/14/2007 at 8:02 am #44561AnonymousInactive
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).08/15/2007 at 4:29 am #44562MIKE SZURAParticipant
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.08/22/2007 at 3:42 pm #44563Jim FarmerParticipant
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 in 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 accelerate for launch, but maybe worth experimenting with.
Good luck. I’ve got an extra set of Poacher plans if you want them!08/22/2007 at 4:18 pm #44564Bill ShailorParticipant
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!08/23/2007 at 12:47 am #44565AnonymousInactive
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.
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