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[98.197.231.39]) by mx.google.com with ESMTPS id s4sm7031785igb.1.2012.07.15.13.27.00 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 15 Jul 2012 13:27:01 -0700 (PDT) Message-ID: <50032793.5000803@gmail.com> Date: Sun, 15 Jul 2012 15:26:59 -0500 From: Dave User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Prop leading edge tape References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------070405010300030409080206" This is a multi-part message in MIME format. --------------070405010300030409080206 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Just so we can quantify the forces involved... To calculate the number of G the propeller tip is subjected to you can use the following formula: G = RPM * RPM * DIAM / 70438 2600 rpm on a 66 inch prop is over 6000 G's at the tip. GRAMS and OUNCES of imbalance are significant at this level of play. Dave On 7/15/2012 11:41 AM, Chris Barber wrote: > > I don't think the vibration was due to it not being balanced in > flight cuz as you say, it is pretty light, I think it was due to it > ripping off somewhat gradually, flopping in the wind and causing a > distortion to the prop path until it ripped off completely. It did > clear up after a moment, but I got my butt back on the ground regardless. > > ------------------------------------------------------------------------ > *From:* Rotary motors in aircraft [flyrotary@lancaironline.net] on > behalf of Bill Bradburry [bbradburry@bellsouth.net] > *Sent:* Sunday, July 15, 2012 11:29 AM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Prop leading edge tape > > Chris, > > Is that tape heavy enough to unbalance a blade to the point that you > would feel it in flight? It seems that it would be pretty light?? > > Bill B > > ------------------------------------------------------------------------ > > *From:*Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] > *On Behalf Of *Chris Barber > *Sent:* Sunday, July 15, 2012 10:59 AM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Prop leading edge tape > > I had my forth flight yesterday. I am still just circling the field. > Everything was going well. Temps and pressures were all well in the > green and I was "playing' (ok, a kinda cavalier term for testing) with > prop pitch, trim and power settings when I suddenly felt a distinct, > slight to moderate vibration coming from the rear of the plane. I > called the tower and with calm winds was cleared for any runway. I > did a tight right turn to 22 and landed. Has it been mentioned that > these canards really don't want to land...I floated quite a bit down > the runway...gotta not try to bleed off speed by slightly lifting the > nose.....damned bad Cessna habits ;-) > > Anyway, I landed and taxied back to the hangar, the vibration had > stopped. I got out and did my quick inspection and it was immediately > obvious that one of the prop leading edge tapes had departed the craft > and another was starting to tear off. Well, at least it seems I > quickly discovered the problem...kinda what testing is all about. > > This is an IVO in flight adjustable prop on my Velocity. I have been > using the stainless steel prop tape as provided by IVO. I used the > same tape during ground testing, but replaced it all just before first > flight. Interestingly, it was pretty difficult to get off...as in it > required quite a bit of force. I did have some issue with the > tape un-attaching a bit during ground testing at the edges but had > hoped it would be okay once I replaced it and secured it better. > > IVO has an online video showing how to install. It is quite straight > forward, but I did note they now add some superglue to the edges of > the tape. I do not recall that being a part of it when I got the > prop, however, I did see the video before the latest tape replacement > and I DID add the superglue to the leading edge. I also was > very thorough when cleaning the prop before adding the tape....I think > I used Acetone for this step. > > Anyway, I have not had success with the method in the video. I was > thinking of masking off the prop except where the tape goes and > applying some of the 3M Super 77 (I think it is the 77...red can) to > attach the tape. I had good success with this when sticking sandpaper > to long I-beams for sanding my wings, needing heat to ultimatley > removing it...alas, sanding blocks and props are two different creatures. > > So? What say ye? Ideas, comments etc. I had one person mention that > they don't like the tape but understand its use to help protect the > prop. Do we know if it is doing more than protecting from minor fod > and, I guess rain?? > > Thanks in advance folks. > > Chris > --------------070405010300030409080206 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit

Just so we can quantify the forces involved...

To calculate the number of G the propeller tip is subjected to you can use the following formula: 

G = RPM * RPM * DIAM / 70438


2600 rpm on a 66 inch prop is over 6000 G's at the tip. GRAMS and OUNCES of imbalance are significant at this level of play.

Dave


On 7/15/2012 11:41 AM, Chris Barber wrote:

I don't think the vibration was due to it not being balanced in flight cuz as you say, it is pretty light, I think it was due to it ripping off somewhat gradually, flopping in the wind and causing a distortion to the prop path until it ripped off completely.   It did clear up after a moment, but I got my butt back on the ground regardless.

From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of Bill Bradburry [bbradburry@bellsouth.net]
Sent: Sunday, July 15, 2012 11:29 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Prop leading edge tape

Chris,

Is that tape heavy enough to unbalance a blade to the point that you would feel it in flight?   It seems that it would be pretty light??

 

Bill B

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Chris Barber
Sent: Sunday, July 15, 2012 10:59 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Prop leading edge tape

 

I had my forth flight yesterday.  I am still just circling the field.  Everything was going well. Temps and pressures were all well in the green and I was "playing' (ok, a kinda cavalier term for testing) with prop pitch, trim and power settings when I suddenly felt a distinct, slight to moderate vibration coming from the rear of the plane.  I called the tower and with calm winds was cleared for any runway.  I did a tight right turn to 22 and landed.  Has it been mentioned that these canards really don't want to land...I floated quite a bit down the runway...gotta not try to bleed off speed by slightly lifting the nose.....damned bad Cessna habits ;-)

 

Anyway, I landed and taxied back to the hangar, the vibration had stopped.  I got out and did my quick inspection and it was immediately obvious that one of the prop leading edge tapes had departed the craft and another was starting to tear off.  Well, at least it seems I quickly discovered the problem...kinda what testing is all about.

 

This is an IVO in flight adjustable prop on my Velocity.  I have been using the stainless steel prop tape as provided by IVO.  I used the same tape during ground testing, but replaced it all just before first flight.  Interestingly, it was pretty difficult to get off...as in it required quite a bit of force.  I did have some issue with the tape un-attaching a bit during ground testing at the edges but had hoped it would be okay once I replaced it and secured it better.

 

IVO has an online video showing how to install.  It is quite straight forward, but I did note they now add some superglue to the edges of the tape.  I do not recall that being a part of it when I got the prop, however, I did see the video before the latest tape replacement and I DID add the superglue to the leading edge.  I also was very thorough when cleaning the prop before adding the tape....I think I used Acetone for this step.

 

Anyway, I have not had success with the method in the video. I was thinking of masking off the prop except where the tape goes and applying some of the 3M Super 77 (I think it is the 77...red can) to attach the tape.  I had good success with this when sticking sandpaper to long I-beams for sanding my wings, needing heat to ultimatley removing it...alas, sanding blocks and props are two different creatures.

 

So? What say ye?  Ideas, comments etc.  I had one person mention that they don't like the tape but understand its use to help protect the prop.  Do we know if it is doing more than protecting from minor fod and, I guess rain??

 

Thanks in advance folks.

 

Chris



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