Nose wheel fairing causing vibration?

Hello all,

I’ve been chasing some pretty significant vibration that I feel especially strong in the area of the floor, seat, control stick, etc. I’ve checked and fixed all of the standard things like baffle to cowl, dynamic balance, loose stuff, etc, but it still persists. It’s worst at high power settings with lower RPM when the prop is at low pitch. Im starting to think I might have a hard to diagnose aerodynamic buffet coming off the prop and wonder if it could be vibrating my nose wheel fairing. I did a flight without the fairing last week and it seemed better but had to cut my flight short. My nose wheel fairing bracket does flex up and down a bit so I’m thinking of strengthening it. I checked and the nose wheel does rotate in flight (Berringer sealed bearing) but only about 150 RPM so I don’t think that’s fast enough to cause the higher frequency vibration I’m feeling.

Anyone have any more ideas or has anyone ever tried strengthening the nose wheel fairing?

I have a Barrett 540, EFII System 32, Whirlwind HRT 375, and a Showplanes Cowl.

I had a pretty heavy vibration that actually had me spooked that something was seriously wrong with my RV-14. (Same nosewheel system)
I checked the airframe for anything loose but since it actually changed with RPM, I was convinced it must be something with the engine/alternator. I had a handful of theories and none panned out. There were 2 consistencies to it.
1) I felt nothing wrong on the ground or in climb, only after I leveled out.
2) It varied by RPM...and I told a friend it felt a lot like the shudder that happens when you first lift off and your tire is still spinning, only constant.

After going through my list, it turned out to be my nosewheel bearings were simply too free spinning, and my wheel was spinning in flight. That explained why it did it when I leveled off. Snugged up the preload a little so it wouldn't spin so freely and it was all gone.

Not saying not to check your other stuff but, I'd definitely check that nosewheel. You may think it only spins slowly in flight but maybe it's more than you think.

Exhaust Palpitations

Checked the Exhaust direction for palpitations along the hull bottom? Does the vibration settle down with RPM changes? Not a RV10 but I sent a picture of the exhaust tubes and their relationship under the Hull and Clint at Vettermans Exhaust said "Not Good" He sent 45 degree add-on tips to me for only $60. They Worked !! Smooth now.

N40ES said:

Checked the Exhaust direction for palpitations along the hull bottom? Does the vibration settle down with RPM changes? Not a RV10 but I sent a picture of the exhaust tubes and their relationship under the Hull and Clint at Vettermans Exhaust said "Not Good" He sent 45 degree add-on tips to me for only $60. They Worked !! Smooth now.

Click to expand...

My guess is that this is okay. Anyone?

Mark

TimO said:

I had a pretty heavy vibration that actually had me spooked that something was seriously wrong with my RV-14. (Same nosewheel system)
I checked the airframe for anything loose but since it actually changed with RPM, I was convinced it must be something with the engine/alternator. I had a handful of theories and none panned out. There were 2 consistencies to it.
1) I felt nothing wrong on the ground or in climb, only after I leveled out.
2) It varied by RPM...and I told a friend it felt a lot like the shudder that happens when you first lift off and your tire is still spinning, only constant.

After going through my list, it turned out to be my nosewheel bearings were simply too free spinning, and my wheel was spinning in flight. That explained why it did it when I leveled off. Snugged up the preload a little so it wouldn't spin so freely and it was all gone.

Not saying not to check your other stuff but, I'd definitely check that nosewheel. You may think it only spins slowly in flight but maybe it's more than you think.

Click to expand...

I put a dot of paint on the nose wheel and recorded a video from the wingtip. At 170 kts it was spinning 2.5 times per second which isn’t real fast compared to takeoff. It was slower most of the time. Either way, I’ve got a sealed bearing which isn’t able to be snugged up to stop the freewheeling. I have a hard time coming up with an idea to stop the rotation otherwise.

TimO said:

I had a pretty heavy vibration that actually had me spooked that something was seriously wrong with my RV-14. (Same nosewheel system)


After going through my list, it turned out to be my nosewheel bearings were simply too free spinning, and my wheel was spinning in flight. That explained why it did it when I leveled off. Snugged up the preload a little so it wouldn't spin so freely and it was all gone.

Not saying not to check your other stuff but, I'd definitely check that nosewheel. You may think it only spins slowly in flight but maybe it's more than you think.

Click to expand...

I will echo what Tim said. I had a vibration on my 10 that only occurred right after takeoff and then again when I was descending. Thought there was an issue with my engine. After mounting some cameras on the plane and then flying with my nose wheel pant off, I could see that my nose wheel was spinning pretty fast. I tightened up the axle nut and the problem went away. Spinning your wheel by hand should have the wheel rotate one or two times and stop, if you can spin it fast by hand and it keeps spinning freely, it’s not tight enough. If you search through VAF, you should find my videos.

eastonale said:

My guess is that this is okay. Anyone?

Mark

Click to expand...

If I remember correctly, early 10 exhausts had short stacks like those and folks got drumming on the belly skin. Vetterman went to longer exit pipes and that eliminated the drumming. I would call clint at vetterman and get his opinion. He can sell you extensions that may help.

Take a look at modern 10 pics and you will see they have about a 1' pipe coming out of the cowl and that dumps the exhaust a good bit further from the belly than yours. A bit more drag, but eliminates that unpleasant noise.

Larry

cderk said:

I will echo what Tim said. I had a vibration on my 10 that only occurred right after takeoff and then again when I was descending. Thought there was an issue with my engine. After mounting some cameras on the plane and then flying with my nose wheel pant off, I could see that my nose wheel was spinning pretty fast. I tightened up the axle nut and the problem went away. Spinning your wheel by hand should have the wheel rotate one or two times and stop, if you can spin it fast by hand and it keeps spinning freely, it’s not tight enough. If you search through VAF, you should find my videos.

Click to expand...

Unfortunately, with sealed bearings, tightening the axle does nothing to increase drag on the spinning nose wheel. Yes, it’s very loose and free spinning.

Does anyone have a suggestion as to how to stop the wheel from spinning since tightening the axle wont do it?