Today's Message Index:
----------------------
1. 04:59 AM - Re: Sum up the vibration issue for me (Stewart, Michael (ISS Atlanta))
2. 07:16 AM - Re: Re: Sum up the vibration issue for me (Kevin Shannon)
3. 03:08 PM - 1st flight (Tom Martin)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Sum up the vibration issue for me |
--> Rocket-List message posted by: "Stewart, Michael (ISS Atlanta)" <mstewart@iss.net>
Update:
I installed the Lord J-9613-12 mounts last night and took a quick night
hop for a feel.
Preliminary results through the "butt" instrument reveals about 70% of
the vibration is gone. This is really good news. Here are my
observations:
1. These mounts are a direct replacement for the VIP50011-20, vans part
number EA DYNA VI-STD I bought from Vans. Engine hangs in the exact same
position
2. Mount "Looks" identical to the old with the exception of the center
shaft collar which has a rubber boot molded to it.
3. The old mounts with 60 hours had taken a set and a little out of
round. Since I have never removed a used pair of these before I have no
idea if this is normal behavior
4. Cost was $400 and was well worth it
5. Install took 3 hours. Should have been 1.5 but I TRIED to do it with
out an engine hoist, using a floor jack and it was a futile attempt.
Once I got a hoist from a neighboring hanger, I could work the mounts
and the bolt with ease. DUH!
6. My real test comes when I mount my highly sensitive "vibration
meter", my XM radio. It sits on a docking station, hard mounted on the
floor tray and shakes with the vibration. It tremendously exaggerates
the vibration and makes it easy to see any progress. Ill do that this
weekend. Left it at home by accident yesterday. Imagine if you had your
cell phone on the dash of your car, mounted up right and had a tire out
of balance. It would shake like crazy and when you did balance the tire
you would expect to see less vibration in the phone. Same Same
7. For the first time I was able to feel differences in smoothness in
the airframe at various RPM's. The old vibration masked any chance of
doing that. In my 10 minute flight 2400 seemed the sweet spot, but much
more flying needed with my "vibration meter"
8. I still have some very slight vibration but now I feel this is
getting nick picky now. I can certainly enjoy this setup for now before
making any rash decisions like changing props, which I may still do...
But the pressure to do this is off my shoulders for a while.
9. If I had the decision to make from the building phase, I would have
installed these to begin with, or perhaps the J-3804-20 used by Van's on
the 10. Those where much smaller and would no doubt be a harder mount
which it would seem made my issue better. I have no doubt that there is
more science to that but that's my sense. Hartzell told me the best
vibration results they have tested were with phenolic blocks, but of
course this is not a viable long term solution for manufacturing at this
point.
I consider the matter closed for now. I HOPE that the new mounts hang in
over time. The old ones felt fine on the first few flights, and got
worse with time. Thanks to all you buzz heads on the 3rd order harmonics
stuff, prop information, and detailed info on your experiences. This has
been a great thread. Probably be a few followup's to this by others.
Look fwd to reading them.
Best,
Mike
A recap for you all on the Rocket list so you know where I am.
I installed on an RV-8 an IO-540 c4b5 with a custom prop built from a
shop in NC. Certified engine overhaul.
My hub is a HC-C2YR-1B and my blades are F-8465-7R chopped 2"
Couple of dynamic balances by 2 different guys. Both with identical
readings and a good balance. One even hooked up multiple units to the
front and rear case to check for crank and so forth. Both said the
engine is great and only took a small bolt and nut to balance.
Engine runs great with a nice engine monitor getting egt's peaking w/I
.1gph. All compressions are 77+ in 60 hours of flight.
I have the Vans purchased Vibration Isolator Products, their part number
VIP50011-20, MFG 15332.
I have a light annoying vibration more noticeable at lower RPM's.
I have a friend with a Super 7 I have flown with the exact setup I have,
prop and all from the same shop, and his vibration is so bad I consider
it unsafe. Just another data point.
Hartzell engineer (Les Doud who has been very responsive over e-mail)
told me to try the mounts vans uses on the RV-10, Lord J-3804-20. I
tried to install and immediately found that these are not direct
replacements for the ones I have and would have brought the engine about
1" closer to the firewall. NOT happening. ARGH!
Received lots of great threads on folks with experience with this stuff.
Many have exactly what I have in setup with no issues, some do. Those
that did, changed to the MT, or other 3 blade, with good success. That
will be the last resort for me. That's a big dollar nut to crack for the
small vibration I have.
Spoke to Lord yesterday (Paul Snyder) and he suggested the Lord
J-9613-12 mount used on Navajo's and Cherokees. So I got that on order
and should get installed in the next couple of days.
Thanks to Jimmy Baker, Bob Japundza et all for the great on/off lists
messages. Good stuff.
Will report finding as I go. If the mounts don't work for what ever
reason, I plan to try and get Hartzell to pony up a pair of blended
blades as a test bed for this problem. They have expressed interest as
they are loosing a lot of business to MT in our market. Thanks to Jimmy
for working this.
Best,
Mike
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Sum up the vibration issue for me |
--> Rocket-List message posted by: "Kevin Shannon" <kshannon@seanet.com>
Great stuff Mike, glad to hear of your success. Valuable info for guys
like me looking ahead at these issues.
Do not archive
Kevin Shannon
HRII building wings
Update:
I installed the Lord J-9613-12 mounts last night and took a quick night
hop for a feel.
Preliminary results through the "butt" instrument reveals about 70% of
the vibration is gone
[SNIP]
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> Rocket-List message posted by: "Tom Martin" <fairlea@amtelecom.net>
Charlie Douma of Brampton Ontario, Canada, had his first flight in his new
HRII. I am posting this on his behalf and I am not sure what his serial
number is. Previous to this he has been a long time Van's supporter and has
built two RV3s, a RV4 and a RV8. A few years ago we swapped rides one day,
he got to go with me in my HRII and I got my first ride in a RV8. After
that he built a rocket and I did not build a RV8. Nothing against RV8, it is
a fine airplane, but there really is no comparison in looks or performance!
Tom Martin
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|