Saturday, October 24, 2020

Adding a Better Roll Trim

Roll trim is very good to have in the Q-200. Not only do you need to compensate for the weight of a passenger, but roll trim needs change with your speed.  For instance, I notice a big difference when I slow down to landing pattern speeds.

For the longest time, I had the turnbuckle mod on the elevator push rods.  This worked okay, but it was a little hard to adjust, and I found mine seemed to change with the airframe vibration and I'd had to keep on adjusting it.  I was corresponding with Mathew Curcio and he shared his method, and like a true innovator, I copied it.  I really like it.  It's easy to adjust and it and it doesn't change on it's own.  If someone wanted to take it a step further, a guy could install some kind of motor and control it with a switch. 

It's a single rod with the knob fixed to one end and a washer to the other. I installed a couple of phenolic bearing blocks in each bulkhead and also a friction brake, similar to the plan's elevator trim brake.

I've been using setup this for about a year now and I really like it. I'm not going to describe how to make it, the photos should speak for themselves. Click on the photos for an enlarged view. Please post any questions in the Comments.








Saturday, October 03, 2020

A photo description of an old repair - Canard wrinkle

Better than 10 years ago I experienced a hard landing with a passenger aboard.  We landed pretty hard and bounced back into the air. I did a go-around and landed much better the second time. When I got to the gas pump, I discovered a nasty wrinkle in the upper skin. 

In this post I will provide a photographic description of the repair. Click on the photos for a better look. Thanks to Charlie Johnson for the repair advice and C-Rod for the layup and vacuum bagging help.

Initial wrinkle


Drew outline of apparent damage.


Coin tap test reveals extent of the delamination.


Take the weight off of the canard prior to repairs.


Damage to foam revealed.


Dug out the foam.



Decided the best way was to go all the way to the lower skin and back to the spar. The spar was  not damaged.


Fit a foam block.


In order to properly fit block all the way down to the skin, it was necessary to split the block front-to-rear, then I could eyeball each side individually.



Lots of wet micro was added to bond the foam in place.  We found the block didn't want to seat, so the use of a vacuum pump was necessary to pull the block all the way down and to eliminate voids.  It worked well.





Get out the Sawzsall for initial carving
.

Getting close to final shape.



Masked off the area to be repaired. 


The existing fiberglass was beveled according to standard composite repair practices, as called out in the education section of the original plans. We trenched the split micro line, since it was a too hard sanding point.


Each line represents how far each repair ply will go. The smallest piece goes on first, then progressively working out to the largest. I forgot exactly how many plies I used. Maybe 5 or 6.


All the fiberglass plies have been added.  Here, the epoxy is still wet.



At the last minute I decided to peel-ply the whole thing.



After the layup has cured for a couple of days, the peel-ply was removed and dry micro applied.


Sanding begins.


After coarse sanding, scratches and pinholes remain.  This will be taken care of by using the epoxy wipe method.


Final sanding completed, ready for epoxy wipe.


After epoxy wipe is complete, all scratches and pinholes are gone!


Prepare for prime, paint and buffing.


Ready for racing!