REFLECTOR: VGs
David Ullman
ullman at robustdecisions.com
Fri Jun 8 08:07:23 CDT 2012
Scott,
Please enlighten me (us). It is my understanding that Laminar flow airfoils
are designed to keep the boundary layer laminar as far back on the wing as
possible, before it goes turbulent. I believe that a well designed laminar
section can get this point back to over 50%. However, reality (bugs, paint,
water) usually trips it sooner. VGs trip and laminar flow to turbulent at
the 30% point (where they are mounted approximately (I am not at my plane to
measure this)). Turbulent flow in the boundary layer sticks to the wing
better, hence the better aileron authority. But, it is messier, so more
drag. What about this is not correct?
David Ullman
N444DX
President EAA 292
541-754-3609
david at davidullman.com
-----Original Message-----
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Sent: Thursday, June 07, 2012 5:00 PM
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Subject: Reflector Digest, Vol 87, Issue 40
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Today's Topics:
1. Re: VG's (Scott Derrick)
2. Re: Update on 444DX (jerry at jlbent.com)
3. Re: Update on 444DX (Scott Derrick)
----------------------------------------------------------------------
Message: 1
Date: Thu, 07 Jun 2012 16:26:10 -0600
From: Scott Derrick <scott at tnstaafl.net>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Subject: Re: REFLECTOR: VG's
Message-ID: <i7vked10vkpx5hwp8eyyg228.1339107970233 at email.android.com>
Content-Type: text/plain; charset="utf-8"
I think there is a definite misunderstanding of what VG's do and what a
liminar flow wing needs.
Mark Magee <edjonesbrady at gmail.com> wrote:
>All,
>I think David frames the problem properly from the original thread (italics
>added):
>---------------------------------------------------------------------------
----------------------------------
>On 6/6/2012 11:06 PM, David Ullman wrote:
>I now have about 27 hours on 444DX. Getting things sorted out. I have
been
>to 10,500 ft and over 200kts (in a dive). I have done both low and
power-on
>mushes. I cant call them stalls as it doesn't. Around 50 kts it just
>mushes. I still have roll and yaw control all the way down. Overall the
>plane is very easy to handle at any speed. I hate the thought that this
may
>be due to the vortex generators. * I just cant intellectually get past the
>fact that I have put vortex generators on a laminar flow surface.*
>
>---------------------------------------------------------------------------
-----------------------------------
>
>I can't either. A laminar flow surface and wings are designed to -avoid-
>turbulent flow of all types, particularly vortexes.
>One reason they go so fast.
>In my mind applying VG's to a Velo is like the old F-4's flying around full
>throttle with the drag chute deployed in flight.
>
>Mark
>
>_______________________________________________
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Message: 2
Date: Thu, 07 Jun 2012 17:54:26 -0500
From: <jerry at jlbent.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Subject: Re: REFLECTOR: Update on 444DX
Message-ID: <20120607225426.21435.qmail at server263.com>
Content-Type: text/plain; charset="iso-8859-1"
Another thought would be to shorten the opposite leg. That would put the
holes above the stress point and should be about as strong as the original.
It doesn't sound like you have any prop clearance concerns with so small a
change. Actually, I would think that the change needed by shortening would
be a lot less than the increase due to the geometry.
Jerry Brainard
Jerry at JLBEnt.com
-------Original Message-------
From: Scott Derrick
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Update on 444DX
Sent: Jun 07 '12 7:58am
David,
sounds like you are making great progress on your shakedown phase. It
really feels good when things start clicking.
I'm not sure about your stall work and John's comment about deep stall.
With a single pilot and not much fuel, and if your a light weight that
speed doesn't seem unreasonable. I'm assuming you did a thorough W&B?
There are characteristics to a deep stall entry that I can't remember
off hand? Maybe somebody could chime in?
Don't you just love autopilots! They are the single pilots best friend!
When remounting your main axle, I'd just clean the hole real well and
fill with flox.If you have room a few layers of bid wouldn't hurt. I
think the main stress within the axle flange area is side to side so
fill it tightly, probably a good idea to clamp it real tight during cure
to insure the flox is compressed as the inner core of the leg is during
construction.
Scott
-------- Original Message --------
Subject: REFLECTOR: Update on 444DX
From: David Ullman <[LINK:
http://mbox.jlbent.com/compose.php?to=ullman@robustdecisions.com]
ullman at robustdecisions.com>
To: [LINK: http://mbox.jlbent.com/compose.php?to=reflector@tvbf.org]
reflector at tvbf.org
Date: 06/06/2012 10:06 PM
> I now have about 27 hours on 444DX. Getting things sorted out. I have
been
> to 10,500 ft and over 200kts (in a dive). I have done both low and
power-on
> mushes. I cant call them stalls as it doesn't. Around 50 kts it just
> mushes. I still have roll and yaw control all the way down. Overall the
> plane is very easy to handle at any speed. I hate the thought that this
may
> be due to the vortex generators. I just cant intellectually get past the
> fact that I have put vortex generators on a laminar flow surface.
Anyway, a
> very easy pane to fly.
>
> Playing with stalls today as I was trying to calibrate the Angle of
Attack
> sensor in the Dynon. I couldn't get it to calibrate. I need to check my
> plumbing. It compares the pressure on the AoA port with pitot and static
> ports. They are both working fine so I need to see if the AoA line in
> clogged or ????
>
> Yesterday I turned on the Autopilot for the first time. I went to 9,000
and
> tried altitude and the heading. Both worked with the Dynon settings and
I
> was able to dial in heading and altitude changes. Pretty cool. I used
it
> again today. Seems to work as I expected. I have never flown a plane
with
> an autopilot before so my expectations were pretty ideal.
>
> My squawk list is getting shorter. One that I need to do, is remount one
> wheel. I have fixed gear and the wheels were mounted at the factory.
> Before I bought the kit the previous owner paid for some work to be done
by
> Velocity. I didn't realize that I had a problem until after I had
assembled
> the plane for the first time in a hangar (not my garage). I was working
on
> the rudders and realized that I could reach the top hinge on one side and
> not the other. It was a "what?" moment. After measuring, one wing tip
is a
> good 2" lower than the other. The only real problem is that I cant top
off
> the tanks as fuel will flow to the lower tank. After careful measuring,
I
> need to raise one wheel by .6". I am a little concerned about the extra
> holes in the strut, but I suspect it is not a big deal. I wish it had
been
> done right the first time.
>
> All-in-all I am really enjoying shaking out the issues and almost have a
> machine that I can trust. In July I will be doing some calibration
> measurements and will report on the results of these tests.
>
> David Ullman
> N444DX
> President EAA 292
> 541-754-3609
> [LINK: http://mbox.jlbent.com/compose.php?to=david@davidullman.com]
david at davidullman.com
>
>
>
>
> _______________________________________________
> To change your email address, visit [LINK:
http://www.tvbf.org/mailman/listinfo/reflector]
http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery! www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: [LINK:
http://www.tvbf.org/archives/velocity/maillist.html]
http://www.tvbf.org/archives/velocity/maillist.html
>
--
There is no fear in love; but perfect love casteth out fear.
Bible, 1 John iv. 18.
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Message: 3
Date: Thu, 07 Jun 2012 17:58:31 -0600
From: Scott Derrick <scott at tnstaafl.net>
To: jerry at jlbent.com, Velocity Aircraft Owners and Builders list
<reflector at tvbf.org>
Subject: Re: REFLECTOR: Update on 444DX
Message-ID: <7qjs8kajhdhshuc5gh84gdta.1339113511149 at email.android.com>
Content-Type: text/plain; charset="utf-8"
Good call
jerry at jlbent.com wrote:
>Another thought would be to shorten the opposite leg. That would put the
>holes above the stress point and should be about as strong as the original.
> It doesn't sound like you have any prop clearance concerns with so small a
>change. Actually, I would think that the change needed by shortening would
>be a lot less than the increase due to the geometry.
>
>
>Jerry Brainard
>Jerry at JLBEnt.com
>
>
> -------Original Message-------
>From: Scott Derrick
>To: Velocity Aircraft Owners and Builders list
>Subject: Re: REFLECTOR: Update on 444DX
>Sent: Jun 07 '12 7:58am
>
>David,
>
>sounds like you are making great progress on your shakedown phase. It
>really feels good when things start clicking.
>
>I'm not sure about your stall work and John's comment about deep stall.
>With a single pilot and not much fuel, and if your a light weight that
>speed doesn't seem unreasonable. I'm assuming you did a thorough W&B?
>There are characteristics to a deep stall entry that I can't remember
>off hand? Maybe somebody could chime in?
>
>Don't you just love autopilots! They are the single pilots best friend!
>
>When remounting your main axle, I'd just clean the hole real well and
>fill with flox.If you have room a few layers of bid wouldn't hurt. I
>think the main stress within the axle flange area is side to side so
>fill it tightly, probably a good idea to clamp it real tight during cure
>to insure the flox is compressed as the inner core of the leg is during
>construction.
>
>Scott
>
>-------- Original Message --------
>Subject: REFLECTOR: Update on 444DX
>From: David Ullman <[LINK:
>http://mbox.jlbent.com/compose.php?to=ullman@robustdecisions.com]
>ullman at robustdecisions.com>
>To: [LINK: http://mbox.jlbent.com/compose.php?to=reflector@tvbf.org]
>reflector at tvbf.org
>Date: 06/06/2012 10:06 PM
>
>> I now have about 27 hours on 444DX. Getting things sorted out. I have
>been
>> to 10,500 ft and over 200kts (in a dive). I have done both low and
>power-on
>> mushes. I cant call them stalls as it doesn't. Around 50 kts it just
>> mushes. I still have roll and yaw control all the way down. Overall the
>> plane is very easy to handle at any speed. I hate the thought that this
>may
>> be due to the vortex generators. I just cant intellectually get past the
>> fact that I have put vortex generators on a laminar flow surface.
>Anyway, a
>> very easy pane to fly.
>>
>> Playing with stalls today as I was trying to calibrate the Angle of
>Attack
>> sensor in the Dynon. I couldn't get it to calibrate. I need to check my
>> plumbing. It compares the pressure on the AoA port with pitot and static
>> ports. They are both working fine so I need to see if the AoA line in
>> clogged or ????
>>
>> Yesterday I turned on the Autopilot for the first time. I went to 9,000
>and
>> tried altitude and the heading. Both worked with the Dynon settings and
>I
>> was able to dial in heading and altitude changes. Pretty cool. I used
>it
>> again today. Seems to work as I expected. I have never flown a plane
>with
>> an autopilot before so my expectations were pretty ideal.
>>
>> My squawk list is getting shorter. One that I need to do, is remount one
>> wheel. I have fixed gear and the wheels were mounted at the factory.
>> Before I bought the kit the previous owner paid for some work to be done
>by
>> Velocity. I didn't realize that I had a problem until after I had
>assembled
>> the plane for the first time in a hangar (not my garage). I was working
>on
>> the rudders and realized that I could reach the top hinge on one side and
>> not the other. It was a "what?" moment. After measuring, one wing tip
>is a
>> good 2" lower than the other. The only real problem is that I cant top
>off
>> the tanks as fuel will flow to the lower tank. After careful measuring,
>I
>> need to raise one wheel by .6". I am a little concerned about the extra
>> holes in the strut, but I suspect it is not a big deal. I wish it had
>been
>> done right the first time.
>>
>> All-in-all I am really enjoying shaking out the issues and almost have a
>> machine that I can trust. In July I will be doing some calibration
>> measurements and will report on the results of these tests.
>>
>> David Ullman
>> N444DX
>> President EAA 292
>> 541-754-3609
>> [LINK: http://mbox.jlbent.com/compose.php?to=david@davidullman.com]
>david at davidullman.com
>>
>>
>>
>>
>> _______________________________________________
>> To change your email address, visit [LINK:
>http://www.tvbf.org/mailman/listinfo/reflector]
>http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery! www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives: [LINK:
>http://www.tvbf.org/archives/velocity/maillist.html]
>http://www.tvbf.org/archives/velocity/maillist.html
>>
>
>--
>There is no fear in love; but perfect love casteth out fear.
>Bible, 1 John iv. 18.
>_______________________________________________
>To change your email address, visit [LINK:
>http://www.tvbf.org/mailman/listinfo/reflector]
>http://www.tvbf.org/mailman/listinfo/reflector
>
>Visit the gallery! www.tvbf.org/gallery
>user:pw = tvbf:jamaicangoose
>Check new archives: www.tvbf.org/pipermail
>Check old archives: [LINK:
>http://www.tvbf.org/archives/velocity/maillist.html]
>http://www.tvbf.org/archives/velocity/maillist.html
>
>_______________________________________________
>To change your email address, visit
http://www.tvbf.org/mailman/listinfo/reflector
>
>Visit the gallery! www.tvbf.org/gallery
>user:pw = tvbf:jamaicangoose
>Check new archives: www.tvbf.org/pipermail
>Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
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