Today's Message Index:
----------------------
1. 07:11 AM - Vibration (Milt)
2. 07:26 AM - Re: Vibration (Archie)
3. 08:20 AM - Re: Vibration (arvil@bellsouth.net)
4. 09:23 AM - Re: Vibration (nico css)
5. 09:50 AM - Re: Vibration (Milt)
6. 06:08 PM - re-Vibration (JOHNTMEY@aol.com)
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 |
|
--> Rocket-List message posted by: "Milt" <rocket@swmrmc.org>
Anybody????????????
I have put about 50 hrs on my rocket since I purchased it from Randy Price.
Just had the engine and prop dynamic balanced to .1 ips.
I continue to have a constant airframe vibration (low frequency) that does not
vary with RPM or speed.
It appears whenever I power up (in the air) and remains until I throttle back.
There is visible up and down vibration in the wing tips (approx 1/16-1/8") the
ailerons appear to hold steady in the slipstream as the wing structure moves
up and down.
There is no vibration in the control stick or rudder pedals. The vibration dissappears
when I throttle back for descent.
At first I was concerned it was prop or engine but I think I have eliminated these
as sources.
The shroud around the oil cooler rubs on the airframe engine attach points and
I am going to refabricate this. Also the exhaust is hard mounted to the fuselage
and I am going to install a flexible coupling.
I asked Randy about it and he recalls no "unusal vibrations".
My friends tell me I have been spoiled by 30 years of large twins and am overly
sensitive to vibration.
Others think it is the propwash from the large 2 bladed prop.
Yet others suggest the landing gear maybe wobbling.
I have searched the rocket list archives and have found no mention of this.
Is this something I should worry about?
Anybody have any thoughts on this?
Thanks,
Milt
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 |
|
--> Rocket-List message posted by: "Archie" <archie97@earthlink.net>
----- Original Message -----
From: "Milt" <rocket@swmrmc.org>
Subject: Rocket-List: Vibration
> --> Rocket-List message posted by: "Milt" <rocket@swmrmc.org>
>
> Anybody????????????
>
> I have put about 50 hrs on my rocket since I purchased it from Randy
> Price.
> Just had the engine and prop dynamic balanced to .1 ips.
>
> I continue to have a constant airframe vibration (low frequency) that does
> not vary with RPM or speed.
>
> It appears whenever I power up (in the air) and remains until I throttle
> back. There is visible up and down vibration in the wing tips (approx
> 1/16-1/8") the ailerons appear to hold steady in the slipstream as the
> wing structure moves up and down.
>
> There is no vibration in the control stick or rudder pedals. The vibration
> dissappears when I throttle back for descent.
>
> At first I was concerned it was prop or engine but I think I have
> eliminated these as sources.
>
> The shroud around the oil cooler rubs on the airframe engine attach points
> and I am going to refabricate this. Also the exhaust is hard mounted to
> the fuselage and I am going to install a flexible coupling.
>
> I asked Randy about it and he recalls no "unusal vibrations".
>
> My friends tell me I have been spoiled by 30 years of large twins and am
> overly sensitive to vibration.
>
> Others think it is the propwash from the large 2 bladed prop.
>
> Yet others suggest the landing gear maybe wobbling.
>
> I have searched the rocket list archives and have found no mention of
> this.
>
> Is this something I should worry about?
>
> Anybody have any thoughts on this?
>
> Thanks,
>
> Milt
==============================================
.1 ips may be OK, but it can/should be better.
I have seen, one time, where there was an engine imbalance so bad,
that by trying to remove it with prop balance, it did not work.
This was due to the fact that the engine's mass imbalance factor was in
another
plane, (the accessory end), and attempting to remove it merely "moved"
the center of balance, not to mention the amount of weight needed.
The result was that they disassembled the engine, I balanced everything,
and the problem went away.
Perhaps not your situation, but if you have a two plane balancing device,
this (if it is your problem) can be isolated.
Archie
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: arvil@bellsouth.net
Archie,
I worked on an RV-4 some years back that gave a similar typ vibration, it turnd
out to be that the left gear leg fairing was not straight in the air streem it
only was noticeable at air speeds over 130 mph. It also might be a good Ida to
check around the rudder trim to see if you might be getting a vibration if the
rudder has .016 skin. I would recommend going to .020ths.on the rudder and
elevator skins if it dosent allready have it
Arvil
Archie wrote:
> --> Rocket-List message posted by: "Archie" <archie97@earthlink.net>
>
> ----- Original Message -----
> From: "Milt" <rocket@swmrmc.org>
> To: <rocket-list@matronics.com>
> Subject: Rocket-List: Vibration
>
> > --> Rocket-List message posted by: "Milt" <rocket@swmrmc.org>
> >
> > Anybody????????????
> >
> > I have put about 50 hrs on my rocket since I purchased it from Randy
> > Price.
> > Just had the engine and prop dynamic balanced to .1 ips.
> >
> > I continue to have a constant airframe vibration (low frequency) that does
> > not vary with RPM or speed.
> >
> > It appears whenever I power up (in the air) and remains until I throttle
> > back. There is visible up and down vibration in the wing tips (approx
> > 1/16-1/8") the ailerons appear to hold steady in the slipstream as the
> > wing structure moves up and down.
> >
> > There is no vibration in the control stick or rudder pedals. The vibration
> > dissappears when I throttle back for descent.
> >
> > At first I was concerned it was prop or engine but I think I have
> > eliminated these as sources.
> >
> > The shroud around the oil cooler rubs on the airframe engine attach points
> > and I am going to refabricate this. Also the exhaust is hard mounted to
> > the fuselage and I am going to install a flexible coupling.
> >
> > I asked Randy about it and he recalls no "unusal vibrations".
> >
> > My friends tell me I have been spoiled by 30 years of large twins and am
> > overly sensitive to vibration.
> >
> > Others think it is the propwash from the large 2 bladed prop.
> >
> > Yet others suggest the landing gear maybe wobbling.
> >
> > I have searched the rocket list archives and have found no mention of
> > this.
> >
> > Is this something I should worry about?
> >
> > Anybody have any thoughts on this?
> >
> > Thanks,
> >
> > Milt
> ==============================================
>
> .1 ips may be OK, but it can/should be better.
> I have seen, one time, where there was an engine imbalance so bad,
> that by trying to remove it with prop balance, it did not work.
> This was due to the fact that the engine's mass imbalance factor was in
> another
> plane, (the accessory end), and attempting to remove it merely "moved"
> the center of balance, not to mention the amount of weight needed.
> The result was that they disassembled the engine, I balanced everything,
> and the problem went away.
> Perhaps not your situation, but if you have a two plane balancing device,
> this (if it is your problem) can be isolated.
> Archie
>
Message 4
| 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: "nico css" <nico@cybersuperstore.com>
Surely a dynamic imbalance would vary with the rpm, which Milt said was not
the case. I would suspect the exhaust, perhaps. But the fact that it is
visible in the wingtips is not reassuring. Milt, can you guess the
frequency?
Nico
----- Original Message -----
From: "Archie" <archie97@earthlink.net>
Subject: Re: Rocket-List: Vibration
> --> Rocket-List message posted by: "Archie" <archie97@earthlink.net>
>
>
> ----- Original Message -----
> From: "Milt" <rocket@swmrmc.org>
> To: <rocket-list@matronics.com>
> Subject: Rocket-List: Vibration
>
>
> > --> Rocket-List message posted by: "Milt" <rocket@swmrmc.org>
> >
> > Anybody????????????
> >
> > I have put about 50 hrs on my rocket since I purchased it from Randy
> > Price.
> > Just had the engine and prop dynamic balanced to .1 ips.
> >
> > I continue to have a constant airframe vibration (low frequency) that
does
> > not vary with RPM or speed.
> >
> > It appears whenever I power up (in the air) and remains until I throttle
> > back. There is visible up and down vibration in the wing tips (approx
> > 1/16-1/8") the ailerons appear to hold steady in the slipstream as the
> > wing structure moves up and down.
> >
> > There is no vibration in the control stick or rudder pedals. The
vibration
> > dissappears when I throttle back for descent.
> >
> > At first I was concerned it was prop or engine but I think I have
> > eliminated these as sources.
> >
> > The shroud around the oil cooler rubs on the airframe engine attach
points
> > and I am going to refabricate this. Also the exhaust is hard mounted to
> > the fuselage and I am going to install a flexible coupling.
> >
> > I asked Randy about it and he recalls no "unusal vibrations".
> >
> > My friends tell me I have been spoiled by 30 years of large twins and am
> > overly sensitive to vibration.
> >
> > Others think it is the propwash from the large 2 bladed prop.
> >
> > Yet others suggest the landing gear maybe wobbling.
> >
> > I have searched the rocket list archives and have found no mention of
> > this.
> >
> > Is this something I should worry about?
> >
> > Anybody have any thoughts on this?
> >
> > Thanks,
> >
> > Milt
> ==============================================
>
> .1 ips may be OK, but it can/should be better.
> I have seen, one time, where there was an engine imbalance so bad,
> that by trying to remove it with prop balance, it did not work.
> This was due to the fact that the engine's mass imbalance factor was in
> another
> plane, (the accessory end), and attempting to remove it merely "moved"
> the center of balance, not to mention the amount of weight needed.
> The result was that they disassembled the engine, I balanced everything,
> and the problem went away.
> Perhaps not your situation, but if you have a two plane balancing device,
> this (if it is your problem) can be isolated.
> Archie
>
>
Message 5
| 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: "Milt" <rocket@swmrmc.org>
Nico,
Vibration is in the range of 10-20 cps.
Milt
Message 6
| 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: JOHNTMEY@aol.com
Gents, Mine doesn't fly yet but a couple generous owners have allowed me to
ride their back seat ... one each HR and F-1. I was amazed at the amount of
vibration (rumble, maybe 10 cps) that I felt thru the floorboards / seat on
each one. I thought is was gear-rumble, that is, IF we could retract the gear,
it would go away. It tapered to near-nothing at approach speeds.
do not archive John Meyers Sequim WA
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! --
|