Rudder, stabilator, aft rudder cable routing and small wheels.

Fred Klein outrigger 2

rparigoris — Thu, 28 Nov 2013 12:14:00 +0000

Fred Klein outrigger 1

rparigoris — Thu, 28 Nov 2013 12:14:00 +0000

Fred Klein outrigger eccentric

rparigoris — Thu, 28 Nov 2013 12:15:11 +0000

All Mono Driver / Builders,

I've always marveled at the precision, geometry, and ingenuity of the outrigger retraction / latching mechanism on my monowheel...I recall the first time I heard that satisfying "THAAAWHACK" when retracting the flap and outrigger as the nylon rod engaged the end of FL3 when the wing was resting in its vertical rack. (the pix below shows my stbd outrigger encased in Kingsley Hurst's wonderful fairing).

Alas...when the wing was rotated horizontally and mated to the fuselage, the weight of the outrigger was just enough to prevent full retraction and the nylon rod w/ the outrigger wheel sagged about 3/4". I was disappointed with this, particularly because whatever benefits to be derived from Kingsley's fairing depended upon full retraction, or at least that is what I thought.

Upon inspection, I concluded that the sag was due to an accumulation of the tolerances for fit of the various components of the retracting mechanism, notwithstanding the high precision of their manufacture. Ultimately it became clear that the problem could be solved by a slight increase in the rotation of the outrigger w/ respect to the retraction of the flap.

See Fig. 17, p. 12, chap. 9M of the build manual.

See also Fig. 24, Section 6, p. 16, chap. 9M.

I've accomplished this by putting an eccentric on the leading radius of the spacer OR10. I've made NO alterations to the slot in OR5; however, I have enlarged the 0.25" hole in the plastic washer adjacent in order that the spacer bears fully on the AN960-10L washer. Following trial mock-ups in aluminum, a local machinist has made me a new pair of OR10 spacers from stainless steel; the new spacers still fit in the 0.25" slot in OR5...see photo below alongside standard OR10 spacer.

(The black marking on the side of the new spacer is just marker ink to differentiate it from other trial spacers.)

The results could not be better...the sag is totally eliminated and there is no perceptible difference in the flap retraction / deployment lever movement or amount of force necessary.

My machinist has saved the program for his CNC cutter and is willing to make up more in batches of 10 or more...contact me off list if you'd like a set.

Fred

Y13-11-08

Alternate use of tailwheel clip.

rparigoris — Tue, 26 Oct 2010 06:54:53 +0000

We found a good use for tail wheel clip after a structural failure occured on our small hangar door spring stop.
Y10-10-23

Outriggers 2.

rparigoris — Mon, 17 May 2010 00:34:45 +0000

Ira:
Nylon slowly depolymerizes in sunight leading to embrittlement,
and 14 years of service should have slowly accumulated a number
of small cracks due to constant flexing loads.
Shouldn't these components be replaced at some interval?

Kevin 1:
I too have brought up this subject after several failures. There were lots of replies of lots of failures. Some say replace the nylon legs annually. I believe that nylon is just not the right material for this application.
"There is no sign of previous cracks or damage, they have simply snapped like match sticks." I don't like that failure mode. I have had several failures, one of which ended with taking out my Airmaster Prop. That really hurt.
"Also any alternate material suggestions?" I am testing out some legs made out of 5/8" fiberglass rod material from McMaster-Carr.
I did some load testing in the shop to find that this 5/8" diameter rod has almost the same flex under the same load as the 1 1/4" nylon. However, it has a very different failure mode. It of course does not simply shatter like the nylon. The fibers in tension (on the "leading edge" of the installed leg flexing back) start to snap and separate from the rod. It is a more gradual failure. I think partial damage will show easily during preflight inspection, but I have not yet seen any.
I have attached a drawing that shows the "bushings" that were made (from broken nylon legs) so the thinner fiberglass rod fits in our OR-1 and wheel fork. The complete legs are about 3 ounces lighter,each.So far they are doing well. I just installed them last month before flying to Florida from California and back.
Now I am making new wheel forks to run 105mm inline skate wheels. These will have 5/8" ID tube so the lower nylon socket won't be needed.

Kevin 2:
I had the left one fail while taxi turning right at an average fast walking speed. When the leg breaks, the wigtip just clears the ground. But the noise you may hear from the OR-1 grinding on the pavement made me want to stop right now! The glider pilot in me probably took over and I think I applied the brake. That's the wrong thing to do, especially in a turn away from the low wing. It will nose over MUCH easier in that configuration. That was it for the prop, and the wingtip lost some paint.
I had another one break on a bouncy landing with my insructor in the right seat.No brake applied and some loss of directional control. Damage was limited to the OR-1.
I broke another on a bounced go-around. I thought I heard it break, but of course you can't see it from the cockpit. I made a low pass and saw it littering the runway.That inspired me to do a good landing (finally) and hold the wing up with aileron to a full stop with brake after slowing and turning slightly toward the broken side.
I broke one in the hanger. I was pushing down on the wing tip to see the flex of my newly replaced outrigger and it shattered.
All these failures happened in above freezing temps, but I did not record actual temps. I bought replacement Nylon 6/6 from McMaster.
Look at the data sheets before deciding on the MDS-filled Nylon (available on McMaster site). As I recall, it is no better for this application.
I'll let ya'll know if I ever break one of my fiberglass legs.
Kevin
N211KA

Kevin 3:
Twas not me who suggested use of MDS-filled nylon 6/6 rod...I know nothing of its properties.
I think it was Erich Trombley that said he was using the above...
Re: wheels...I'm not familiar w/ "Easy-Rolls", but the 100 or 105 mm skate (or scooter) wheels spin silently forever...be advised that when buying them you will enter the world of ABEC ratings for various bearings...I opted for #9s but you can go for the ceramics for a few more bucks...I bought my inline wheels online at www.skates.com,,,bushes are also available to enable fitting within the SS forks.
Thanks for that link, they have good service and reasonable prices.
Related comment: From Kevin's drawing, he's apparently mastered the art of machining the factory-stock nylon rod...I had a devil of a time turning down my rods so that they might fit into the OR 1s.
I am fortunate to have a friend close by with a lathe and a milling machine in his garage. He made the drawing and turned the rod into the part drawn. I plan to get with him on drawing up new slim forks for the skate wheels to go with the 5/8" fiberglass legs.
Kevin
N211KA

Nev mentioned lack of moisture a bad thing, don't clean with solvent or paint, like with models and nylon props, probably not a bad idea to boil once a year if in a very dry area?? This way once a year can remove and inspect very close and load test??

Ron,
most polymers become brittle because of a loss of the volitile hydrocarbons
they contain,
the higher the temp generally the faster the loss of these hydrocarbons.
Depending on the material you MAY actually make a polymer based component harder by boiling it and then cooling it.
UV light can and does play a part here too, I suppose you could put some
SPF50 on your outriggers to block those UV's, but seriously some of the new clear films block 99% of UV which would fix the issue if it is UV related
craig

I have been using a different material for my outriggers for the last 6 years without issue. I chose to go with MDS (molybdenum disulfide) filled Nylon 6/6 material. The material is available on line from a number or vendors; I purchased mine from McMaster Carr. The material is very flexible, supposedly has good impact strength and is less subject to UV degradation than other materials. I have yet to break a leg. You might also try and scallop the back face of OR1 in attempt to reduce the stress riser.
Erich Trombley
N28ET Classis Mono 914

Yes, it was me who suggested the use of MDS-filled nylon material from
McMaster-Carr. I did some research during the selection process and if I remember correctly the MDS-filled nylon had the same or better flexural strength, better UV protection and slightly better impact strength. I have had my legs in service for just over seven years without issue. I too am using inline scooter wheels with a slimmed down mounting fork. I will take a picture and post it.
Y10-05-14
Erich Trombley
N28ET Classic Mono 914

Pete Mk1 drive for Mk2 tailwheel.

rparigoris — Tue, 29 Jun 2021 00:59:03 +0000

"Attached is a pic of the tailwheel. It uses the original tailwheel fitting
with the fork removed and a plate bolted on to connect the new control wires
to the MK2 tail wheel. Works well. I did originally fit a Graham Singleton
style set up but we found in practice there was just a bit too much friction
so removed it. In those days there were plenty of spare MK1 tail wheels
about so getting a replacement was no problem."
Y10-03-09

Sternpost vent goes to D panel.

rparigoris — Sun, 17 Jan 2010 21:05:02 +0000

Ian Rickard #505 G-IANI XS Trigear sternpost vent to D panel and port rudder cable hole in sternpost.
Y9-07-18

Stab_profile_4

rparigoris — Tue, 17 Nov 2009 23:27:36 +0000

"PORT" stabilator gets packaging tape on "BOTTOM" surface at root, then applied Expancel/Aeropoxy nice and thick on wet out surface of fuse profile after it was scuff sanded with 80 grit.
See:
Album: Top fuse bond on information and "ProgMess".
for further sanding and filling "ProgMess".
Y9-07-13

Stab_profile_3

rparigoris — Tue, 17 Nov 2009 23:27:36 +0000

"PORT" stabilator gets packaging tape on "TOP" surface at root, then applied Expancel/Aeropoxy nice and thick on wet out surface of fuse profile after it was scuff sanded with 80 grit.
Y9-07-13

Stab_profile_2

rparigoris — Tue, 17 Nov 2009 23:27:36 +0000

"STARBOARD" stabilator gets packaging tape on "BOTTOM" surface at root, then applied Expancel/Aeropoxy nice and thick on wet out surface of fuse profile after it was scuff sanded with 80 grit.
Y9-07-13