What's new

Elevator Grip

jvaliensi

New member
Hi there,
I have a sailplane with a full-flying stab. It rides on a 1/8" carbon rod joiner and has a steel pin thru the bellcrank and stab halves. It slides off too easily. I think after a few rolls a stab half may slide off in flight.
Are there any good tricks to keeping it on better?
 

Konrad

Well-known member
There shouldn't bee too much aerodynamic load pulling the stabs off. I like to bow the trailing wire rod (pin) to give a bit of spring. If that's not practical I like to paint the wire (pins) to give drag (tight fit).
 

jvaliensi

New member
I gave the fuselage a bit of spin w/ the stabs on and one moved out about 2". I know the roll rate is not so fast, but it concerned me a bit. I'll try bending the wire.
Thx
 

purview

New member
jvaliensi,

this is my solution, firstly I changed the original carbon rod to a steel one:
IMG_0876.JPG

the rod must bend to enter into the whole and the less drag the nearer to its sibling
IMG_0878.JPG

after using this method (tight fit) I can assume that I had no troubles in the air. the weakness is the small tail fin and the small diameter of the stab. not comparable to a fixed but advantages too.

happy new year konrad
 

purview

New member
mathematical solution is to calculate the forces when rotating/spin the carbon rod joiner. which force must be achieved in such non-frictionless system? I hope it must be more than 2 spins per second.

with CA, sandpaper and a file you can calibrate the friction (with adding or removing diameter on the rod joiner or inside the whole) more or less it is inadvisable to fly outside the limits. I mostly have to keep the elevator together after a bad touch down. this is also a good sign to look on the rod for fracture issues. but spin tests on the ground must be viable

following with new year blessings
cheers chris
 

Konrad

Well-known member
I'm happy to say I don't recall having an issue with the stabilizer rods in flight. Flight loads seem to keep them in place. Now I sometimes do have a issue during landings. the shedding of the stab can damage the internal linkage. The asymmetric load on the stab mount after a stab is shed has caused problems. SO had the loose stab imbedding itself into a wing been a problem.

I still like a positive attachment system (latch or wheel collar), but this is because of the landing loads not normal flight loads.

I've had wax melt in the heat actually making a nice lubricant.
 

Tim Callahan

New member
guess we don't get that heat up here in the N.W. once you install the bow wax on the rods it acts
liker a vacuum trying to get em off. any way a small bend in a steel rod works very well.
 

purview

New member
this is only on the stab rudder intersect it helps to minimize friction where it isnt needed. it is very old and used it before on highly rotating parts,

slowly move the transmitter stick up and down it should not jump it follows your rudder control linear. it can happen that the grease moves a
bit
IMG_0930.JPG
 

Konrad

Well-known member
Full discloser;
I can't say for sure, but upon giving it a second thought I think I tried bee's wax or skiing wax.

Having lived in Everett I can say it gets hot enough at times.
 

purview

New member
what are the issues with too hot or too cold and using grease on this parts?

is there something i am not aware of?

cheers chris
 
Top