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SHOCK RINGS selection for PA18 experimental

jse18

Registered User
South West of Paris City !
I just started to taxi with my cub after 10 years of work ! :lol:
I selected the 1080HD shock ring based on data from :

http://www.aircraftspruce.com/catalog/lgpages/shock_rings.php
http://www.aircraftspruce.com/catalog/pdf/SHOCK%20CORD%20RING%20APPLICATION%20CHART.pdf
http://www.univair.com/content/supplies_catalog.pdf

My plane weight 950 Lbs empty. I build it on PA18 drawing, I selected the 1080HD.
I install 1080HD that based on selection chart for a PA 18 above considering that my bird has a heavy O-235. And the size of the seat from the WAG drawing.
It behaves differently from my experience of taxi on old PA18 or J3.

On the old "Cubs", If I lift the wing smoothly, I see the landing gear moving and the shock extanting and retracting.
On old "Cubs", it is less that an inch but it moves.

On my plane, it doesn't move at all. I was beileving that after 2 miles of taxi it will fit and respond in the way described above. But it don't.

Does that come from the fact that my shock ring are new ?
Will that become smooth after 2 or 3 jump on the runway ?
What shock ring are you using on your experimental ?
Is that a good idea to mix the strength, example a 1080HD + a softer shock ring ?
 
Last edited:
One complement, I have only shock ring like a cub, I haven't with "hdrosorb unit". Install look like the J3 and early PA18 one (drawing from WAG Aero)
 
The shock cords will get softer with age. It's fairly typical for them to be stiffer when new than later on. I'd be inclined to leave them on and go fly.

The idea of the Hydrasorb is to soften the rebound. They do need a force to extend even without the cord fitted so logically the presence of Hydrasorbs would increase the force to extend the shock-strut as compared to a non-Hydrasorb unit.

Andrew.
 
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