Parkhawk problems...

[henke]

Hi

A friens has a PH that only turns more or less left.... and haveing problem to stay in the air... full right rudder input(125%) is almost enough to keep it straight...

any solution? should TP be locaded as recomened?

/Henke

[Jerry Rose]

Mine did the same thing - except to the right. Since she is turning left, that means the Right Sail is probably tighter than the Left one. The sail that is tighter develops better lift, and makes her want to turn in the opposite direction! There are other things that may be wrong, but this seems to be the most common cause of a tendency to turn in one direction or another.

The first thing to try is to pull the Sail outboard on the Left Wing. The main Carbon Spar has a rubber tip, which should grip the fabric and allow you to tighten the Sail.

The goal here is to set her up so that the Sail has equal tension on the Left and Right Wings. :D

[KeithK]

A rubber tip? my wing fabric slides very easily on both sides. First time I have heard of this. Is it something new?

BTW, I am having the same problem, turns right, can't recover or gain altitude.

[frankenfoamy]

Sean had a great idea of stapling the flaps in place.
They release easy and you just restaple when you need to readjust.

http://rcguy.tripod.com/

[Jerry Rose]

Originally posted by KeithK
A rubber tip?

Yep. Mine came with little rubber caps (white) on the ends of the carbon rods. I found that they still didn't do a perfect job, so I modified them by dipping the rod tip, rubber tip and all, into a can of Star Brite Liquid Electrical Tape. This increased the diameter of the tip cap, and resulted in a "stickier" grip on the fabric. It worked GREAT.

I also like Frankenfoamies thoughts on using staples. Anything that increases the friction between the carbon rod and the fabric sleeve will help you when you are trimming the bird.

Ha! "Trimming the bird" reminds me of Thanksgiving. :cool:

[Jerry Rose]

I forgot to add this picture of my Spars. You can see the rubber tips.

[KeithK]

Is the idea to extend the wings horizontally and stretch the fabric outward as much as possible, then staple/glue the fabric at the end of the spar so it won't slide back?

[Jerry Rose]

As far as trimming the bird goes, the general idea is to get equal lift off of the left and right side of the sail. If one side is looser, the bird will tend to turn in that direction. So when I adjust my sails, I am trying to get the two sides to have the same amount of tension.

When I put the liquid electric tape on the spar, I let it dry completely before inserting into the sail sleeve. There is no gluing here!

It sounds like the stapling method would involve getting the right tension and then locking it in there. Frankfoamy may have to expand on this stapling idea - it sounds cool.

[frankenfoamy]

I idea came from the designer (Sean)

http://rcguy.tripod.com/

[BillB]

I have not flown my just received ParkHawk yet as I am in the process of building it and I noticed that the wing spars were slightly different lengths. One was longer by about 3/32". I don't know if other spars might have the same problem or not but I would think this would cause a problem with tension imbalances as well.

[KeithK]

B.illB,

Interesting point. I never measured mine. I think others have found the same problem as I have, they fly fine for the first several flights (after the trim flights) but then develop lift or pulling to one side problems. I am almost positive my problem came after it sat in the sun a while (mine's black) and the heat caused either the glue to soften, the fabric to stretch, or both. I am going to try the Frankenfoamy staple method on mine and tighten things up.

Keith

[Jim Baxter]

The quickest way to trim the Park Hawk is simply to turn the wing over... I have three of them and it worked for all three. They all fly with very little trim now. Stretching/tightening a wing never worked well at all for me. Also, mix about 50% elevator in with the rudder and it will turn very nicely all the time... JB