Towing Problem- Jr Tow and Launch seminar Info

[Anonymous]

I surprise myself- I did not understand I had a provate mail box here on the forum. So this question is over 6 months old but spoke to the recent semianary at the 2007 MM I did for the Jr flyers (an others)– JIM

My F1A would never come around in a tight enough circle when I had the hook closed and it came in a few times.
I’ve been thinking the excessive wash-out in both wing tips might have been the cause.No amount of rudder would do it.
What do you think?

[Anonymous]

Dick- sorry I did not understand I had private messages, so 6 month late.
Hard to evaluate w/o seeing the model, I’m look at the hook position– the ring pull point needs to be on a 17 degree line from vertical from the CG position. the height of the CG is important. For most configurations today (top of fuselage to hook 2.5 inches, 6 inch dihedral), the up-down postion of the CG is near the bottom of the airfoil so it is convent to measure and mark it. For these configuration the 17 degrees works out to be about .7 inch horizontal between the cg and hook pull point.

If you have a shorter, taller fuselage or a model with much less or more dihedral, the up-down position of the can be above or below the wing.

The next thing is inbd washin. This assumes the tips are washed out equally. If they are withing .030 inch of each other (either way) you should be OK. See the write-up below I did for a Jr seminary I did at the last MM.

Last item is you mentioned no “amount of rudder”. Im assuming this is a conventioan circle model and the problem is the model will not come around the lower circle to be pulled up to the top. When tension is applied, the rudder goes straight – this position is used only to have the model pull up straight. The info below should help. Again sorry for the lateness. Let me know if you already solved the problem and how. Thanks, JIM

2007 F1A Towing and Launch Seminar
Lost Hill, Feb 17, 2007
Jim Parker
Are you towing the model or is the model towing you?
What do I do in a line tangle?
What is a good F1A launch?
How do you make a good launch?
How do I become a World Champion?
GOALS:
– Understanding of the two dominate trim / tow-launch styles
– Circle tow control – Tactical towing
o Up-down- side wind
o Tangle
o Wind
– Consistent performance launches
o Speed
o Release angle
o Pitch up angle
o Bunt recovery pitch
o Bunt recovery turn

DISCLAIMER- not all F1A flyers will agree with all the information that follows. Part of what makes this sport so fun is the different approaches, tactics and style one can take on the road to success. Success is different for everyone- for some it is making a Team, others is flying with dads and friends. The two ideas I wish for you to take from this time is there are different styles, for you to gain a further understanding of the different style. The most confusing thing for new flyers is taking help-instructions from well intentioned but differing flying styles flyers. With the new understanding from today, you will be able to determine the style you wish to pursue and communicate that desire to those willing to help you.

TRIMMING RULES- right circling model
Rule 1. Trim rules are not absolute
Rule 2. The following wash-in trim rules work only if all the other set-up of the model is correct. Example: stiff wings with standard warps: inbd center .010” to /.050” washin, outbd center flat, tips equally washed out .15”-.20”. No slop in wing wires or wing pins / wing wiggler. Straight tail boom and rudder and stab. Correct Hook position. See Peter Alnutt’s F1A set-up and trim article.
Rule 3. Eyeballs are good to see gross problems but the flying model will tell you the details

WASHIN RULE- right circling model under tow, inbd (Rt) center washin produces more drag than lift causing the model to turn inbd (Rt). The more washin, the better the model comes around the downwind circle tow. Effect is greater when the model is low and decreases as the model is towed higher. In fact, with a large amount of washin, at the top of the line just at release, the washin can cause more lift which will roll the model outbd (left).

TWO DOMINATE TRIM / TOW-LAUNCH STYLES:
A. Smaller straight tow washin, Model does not come around the circle tow as well, that is the model will “run” right. Towline tug and lease method is used to get the model around. The “run” characteristics can be used to an advantage to move the model from one side to another The model must be straight before the start of the launch but can be started low to the ground and stay on a straight launch path. That is, getting the model straight is critical at the start of the launch. If the model is not straight, the dreaded left – inverted bunt often happens. If all other aspects of the model is correct, the straight tow rudder should be offset outbd (left) 1/16 to 1/8”.

B. Larger straight tow washin, Model comes a round the circle tow as well. This trim is less prone to lose control on downwind side of a strong thermal. This tighter turn can be used to an advantage when towing in crowded areas. The model takes a curved path. This makes the height and timing is more critical. If the launch is started with model turned too far or too low to the ground, the dreaded right arch to the ground often happens. If all other aspects of the model is correct, the straight tow rudder should be straight—even had better models with very slight rudder.

C. Circle tow incidence close to glide: Pros: better feel in light air conditions. Cons: harder to stall the model to execute a quick circle tow, slower accelerate at start of launch, less pull, less speed
D. Circle tow incidence greater than glide: Cons: poor feel of the light air conditions, too much and model tows like a squirrel. Pros: easier to initiate quick stall turn, quicker acceleration, more pull, more speed

CIRCLE TOW CONTROL – TACTICAL TOWING
Start:
– Know the flyers around you—who circles left? Have an initial plan.
– If going down wind, go early, establish position
– Wait on the ground, read the models on tow, do not need to wait for a model looking good on tow to launch. “ Best flyer on the field is the second model launched in a thermal” Bob Isaacson
Movement:
– Youth- use your athetic advantage- minimum line on the ground
– Practice control “Runs”. Allow the model to run and slack tow to bring around
– Down wind moves
– Calm to low breeze, tow up, half circle and downwind tow- use your athleticism
– Low to medium breeze, tow to half height, stall turn- race down wind w/ model
Tangle:
– Move towards the other flyer, use stall turn if needed. Very last resort is to let go of the line. No Fear, No Guilt—take control- communicate to other flyer if they do not start moving towards you. Do not release line unless it’s the very last resort.
– Consistent performance launches
o Speed
o Release angle
o Pitch up angle
o Bunt recovery pitch
o Bunt recovery turn

CONSISTENT PERFORMANCE LAUNCHES
Speed:
– More is better—athleticism is good but good form is critical.
– Every model will have its critical start point, some more critical than others. Practice to know each model.
– In competition, control of the adrenaline pump is key to making good decisions
Release angle:
– Mechanical Bunters, the release angle is 78 degrees
– Electronic model with increased incidence at unlatch, the release angle is near 90 degrees
Pitch up angle:
– The pitch angle is determined by the release angle and the initial incidence
Launch Path: Two styles, computer simulation indicate little difference in height
– Inside- outside loop. Standard for mechanical model. Less critical, model more up wind at recovery
– Quick pitch up, cruise up at near vertical, hard bunt. Requires electronic model with multiple stab movement/adjustment. More critical unless careful adjustment of cruise angle.
Bunt recovery, pitch: Important to teach you helper to observe the angle and speed of model. It is very difficult for the flyer to see the difference between the following two bunt recoveries:
– Nose high, low speed, the model stalls. Adjust by shortening the time before bunt.
– Model is fast at the end of bunt, causing the model to “come over the top”, when the glide comes in, the nose rises and the model has slowed , then stalls—this happens in about ¼ sec and to the flyer looks like the above situation. Correct by lengthening the time before bunt (cruise time).
Bunt recovery, turn / roll: Remember we talked about too much washin at high speed, at the top of the line stops producing drag and starts producing more lift that rolls the model to the outside (Left) resulting in the dreaded bunting out of the front of the thermal. Options–
– Decrease the inbd washin
– Bias a slight right straight tow rudder
– Zoom Rudder—can be dangerous- use less than 1/16 rudder TE deflections

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