Manual aileron trim knob

[hydroguy2]

I decided I didn't like the lever Vans supplied, so today I tried to buy some AL bar stock. No luck in Podunk, Montana. But I went to a old time machineshop we use for work and ask if he had any for sale or rummage his scrap bins. He said we have no scrap pile, it's all good stuff. I thought "great what's this going to cost?" He was scribbling notes while I described what I needed. Come On! I just need a 6"x2"dia AL bar stock..or something close I'll make it work!!!!!!! Then he said what's it for? Ok, I'm building a airplane, an RV-7. He looked up from his notepad and leaned on the counter and I thought he was going to cry when he said, I've always wanted to build an RV-8. "come on back let's get you some stuff." I spent 30 minutes talking while he loaded me up with various AL sizes. I kept saying that's enough(I only needed a $5 chunk of scrap). Back at the counter, His wife ask about making out an invoice. He said "it's taken care off, he owes me a ride". She said "For all that?" rolled her eyes and walked away. I tried to pay him, but no go...Ride it is!

Annywaayy! here is my first attempt at a new trim knob for between the seats.

[cjensen]

This is EXACTLY what I've been imaging since you and I have been talking about this! Sign me up!!! LOVE IT!!

[weezbad]

what are you doing for friction or reduction. id like to see the finished instal. keep us posted.

[hydroguy2]

what are you doing for friction or reduction. id like to see the finished instal. keep us posted.

Friction will be the same as factory, tighten a bolt to squeeze the plastic block. This will be a direct replacement for the funky handle supplied by Vans. It will take longer to take your old handle off....then it will to put this back on AND use 1/2 the number of tools.

[weezbad]

ahhh i see. i was thinking the electric trim was standard and you modified it. looks nice.

[Spike]

Now that is really nice. I might have to file that away for when it is my turn.

[hydroguy2]

Here's an almost complete 1st draft w/hardware and Vans version for comparison



Installed comparison

[Mike Balzer]

Nice Work,
Looks like you have access to a lathe and other machine shop tools.

Keep up the good work,


Mike Balzer

[hydroguy2]

Nice Work,
Looks like you have access to a lathe and other machine shop tools.

I wish I still had access to a good shop. But for the average hobbyist, good ol' Harbor Freight is ok. I have a decent drill press that's 25yrs old, but when I start building I bought this $149 HF combo horizontal/vertical bandsaw. Take your time, let the saw do the work and It makes perfect cuts in the power hacksaw mode.


Then last winter when I visited my Dad he gave me this 7"x10" HF lathe. It's good enough to turn small aluminum into even smaller aluminum.


These are under powered tools, but treat them well, keep them clean and be patient. They'll do an ok job.

[cjensen]

VERY nice Brian! Keeps looking better and better!

[hydroguy2]

Chad, ya' think that will work for you? I think I'm pretty much done. Maybe some engraving. I may send this one to a friend (with a flying RV) and make sure it works in the air. Next ones will go faster, since I kept good notes.

[cjensen]

I looks to me like it will work great. The size is bigger than I thought (but that's a GOOD thing!), and I would love to hear a flight report on it! Go for it! If it works the way we think it will, I am very happy with the way it looks!

[hydroguy2]

I wondered about the size also. Sam B in Alabama wondered if it was big enough, due to the very slight movment needed. Also when the tension is adjusted you need some grip area for twisting. Oh well we'll see how it works and go from there.

[dons]

Nice work. Just goes to show that it's knowing how to use and how to treat your tools that is just as important as having all the fancy toys.

[hydroguy2]

I sent the prototype to the test pilot. He'll do a complete shake down at various trim settings and probably some inverted stuff(just to be sure).

Then it will come back for some NDT inspections. By then the financial department should have a price calculated. A quick review by legal and we should be good to go.

ok I may have embellished a little. but did send it to Don for a second opinion in a working RV.

[cjensen]

...looking forward to the flight report!

[hydroguy2]

Back to the drawing board. Initial report is that the knob fits well and works fine when solo. But with both seat occupied, there is not enough space between the seats and the Vans lever is easier to use with one finger.

I'm still planning on making something more attractive than the Vans lever.

[cjensen]

No one gets it right the first time!

[Rockyjs]

I really like your machine work. I also played with installing a round knob for the aileron trim. I wasn't thrilled about the Vans aileron trim being "backwards". If you need right wing down you move the handle to the left. after flying, it turns out it's pretty intuitive and you get used to it quickly.

Origianlly my plan was to install a knob that would trim the ailerons in a conventional manner.

I used a round knob that I had laying around and mounted this forward of the handle attach point.about 3 inches The shaft went through the floorboard and an arm was installed. I used a pushrod attached to this arm that crossed from right to left and attached to the actuating arm on the aileron trim assembly. This gave me proper conventional trim. I played with the geometry of the two arms to get some "fine" control (ie short arm on knob, long arm on lever). I needed to relieve the Nylon block for clearance with the pushrod, and decided it was time to get the plane flying now and revisit the aileron trim mod later.
.
I have about 38 hours now during Phase I and the plane flies great. I'll revisit the trim knob again someday, but It's such a blast to fly that I don't want to take the plane apart fixing something that is not broke. Maybe this winter! Besides they are starting to line up for rides. If you think people are a PITA asking you when your going to finish building, wait until you're nearing completion of Phase I test flying.

As a last thought
You might want to locate the knob forward and control the trim lever with linkage on the same side. I think this would provide you with a bit more accessible area to reach the trim knob. Surprisingly, it takes "very" little trim, just a tweak on the handle.

[hydroguy2]

#2 trim knob will probably be a lever type. I like the knob look, but didn't realize the space limitaions were that tight. If flying 2-up, and slight finger motion is required between the seats, I'll make it work. BUT it will be better looking than Vans.

No linkage. I want a simple drop in replacement anyone can install with no fine tuning needed.

Probably won't get back to it for a few weeks, I need to finish my canopy.