REFLECTOR: Reflector Digest, Vol 114, Issue 26
Don Smucker via Reflector
reflector at tvbf.org
Tue Sep 30 07:10:23 CDT 2014
Re VGs
David:
Ditto the kudos! Impressive! I am just finishing up a number of items on N34XL, a FG XL (IO 540), including improvements for the top NACA cooling ducts and will DEFINITELY be adding the larger VGs in front of the scoops instead of the low ones I had planned on. THANKS for your detailed and timely research and report. I am really looking forward to meeting you in person and to shake your hand.
What do you think about putting the large VGs in front of the bottom of fuselage combustion air NACA scoop for ram air pressure increase?
Don Smucker
On Monday, September 29, 2014 11:04 PM, via Reflector <reflector at tvbf.org> wrote:
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Today's Topics:
1. The use of VG to aid cooling (David Ullman via Reflector)
2. Re: The use of VG to aid cooling (Brian Michalk via Reflector)
3. Re: Retractable Gear Issue--- long story
(Bob Jackson (Jax Tech) via Reflector)
4. Re: The use of VG to aid cooling
(Bob Jackson (Jax Tech) via Reflector)
----------------------------------------------------------------------
Message: 1
Date: Mon, 29 Sep 2014 17:09:05 -0700
From: David Ullman via Reflector <reflector at tvbf.org>
To: <reflector at tvbf.org>, <reflector-request at tvbf.org>
Subject: REFLECTOR: The use of VG to aid cooling
Message-ID: <035601cfdc42$c2435aa0$46ca0fe0$@com>
Content-Type: text/plain; charset="UTF-8"
My Velocity has always run hot. I have fixed this with the use of Vortex Generators aiding the flow of air into the NACA ducts on top of the fuselage. For a full report go to:
https://davidullman.com/uploads/THE_USE_OF_VORTEX_GENERATORS_TO_ENHANCE_PUSHER_AIRCRAFT_COOLING.pdf
Comments appreciated.
To see recent photos of N444DX hangared in Independence Oregon, go to:
https://davidullman.com/VelocityPhotos.php
David Ullman
David at davidullman.com
------------------------------
Message: 2
Date: Mon, 29 Sep 2014 21:45:08 -0500
From: Brian Michalk via Reflector <reflector at tvbf.org>
To: David Ullman <ullman at robustdecisions.com>, Velocity Aircraft
Owners and Builders list <reflector at tvbf.org>
Subject: Re: REFLECTOR: The use of VG to aid cooling
Message-ID: <542A1934.8090804 at awpi.com>
Content-Type: text/plain; charset=utf-8; format=flowed
What an excellent write up. Thanks.
On 09/29/2014 07:09 PM, David Ullman via Reflector wrote:
> My Velocity has always run hot. I have fixed this with the use of Vortex Generators aiding the flow of air into the NACA ducts on top of the fuselage. For a full report go to:
>
> https://davidullman.com/uploads/THE_USE_OF_VORTEX_GENERATORS_TO_ENHANCE_PUSHER_AIRCRAFT_COOLING.pdf
>
> Comments appreciated.
>
> To see recent photos of N444DX hangared in Independence Oregon, go to:
>
> https://davidullman.com/VelocityPhotos.php
>
> David Ullman
> David at davidullman.com
>
>
>
> _______________________________________________
> To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector
>
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> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
------------------------------
Message: 3
Date: Mon, 29 Sep 2014 23:32:48 -0400
From: "Bob Jackson \(Jax Tech\) via Reflector" <reflector at tvbf.org>
To: "'Velocity Aircraft Owners and Builders list'"
<reflector at tvbf.org>
Subject: Re: REFLECTOR: Retractable Gear Issue--- long story
Message-ID: <010601cfdc5f$35d99710$a18cc530$@com>
Content-Type: text/plain; charset="utf-8"
Nice job, Jack! Larry (and Scott) know what they're talking about (as usual). I wouldn't depend solely on grease -- I would also sand away some more gear leg and socket clearance. You don't want to have to help the gear down all the way by 'hover' landing each time! Won't your wife ride with you in the back seat -- where are they when you need them?
Bob Jackson
N2XF XL-RG
From: Reflector [mailto:reflector-bounces at tvbf.org] On Behalf Of Laurence Coen via Reflector
Sent: Monday, September 29, 2014 12:02 PM
To: Jack Prock; Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Retractable Gear Issue--- long story
Jack,
First I hear-by award you the Ace Aviator Award for saving the bacon. I also think that from your description of where they hang up, that the top of the gear leg is binding in the socket. If this only happens in flight then the problem is likely with the gear leg pivot. If the bulkhead bushings or the gear leg steel pivot tube are adrift, the torque from wind resistance could misalign the gear tops with their sockets. I greased the gear top socket, not because the gear hung but because they made a groaning sound when I rocked the wings on the ground.
Larry Coen
N136LC
From: Jack Prock via Reflector <mailto:reflector at tvbf.org>
Sent: Sunday, September 28, 2014 1:26 PM
To: 'Velocity Aircraft Owners and Builders list' <mailto:reflector at tvbf.org>
Subject: REFLECTOR: Retractable Gear Issue--- long story
HI,
So I have been doing test flying of my new XL-RG and I was having an issue with the oil not cooling. Turned out the Vernatherm was not closing completely. Made every flight under 15 minutes, which was frustrating. Anyway, this morning I went out to test my latest change to see if the oil temp would stabilize. So within 15 minutes it was steady at 220… YEA! It was nice to not be able to fly and not worry about that.
So after 20 minutes, oil temp steady, I decided to raise the landing gear. Mind you, I had raised and lowered the gear probably 40 or 50 times over the past 8 years, and every time they came up and went down perfectly. I had also made sure that the wheel wells had clearance, since a friend had that issue in his Velo. So they came up great, I was sitting fat, dumb and happy. I then went to lower them and they lowered fine… or so I thought. I looked down and I had two yellow lights on the rear gear. I looked back and they had lowered 90%, but the over center arms had not locked. They were about 2 inches above locking.
I cycled them a half dozen more times, and every time the rear gear would stop at the same point. I don’t have the rear cover panel on, so I can easily see the gear arms. Man it was so frustrating to be sitting there, be able to see them, and not crawl back there to push them down the last two inches.
So I flew around for a while and tried yanking on the yoke a bit to see if I could get them to budge. Mind you I have about a total of 1 hour on the plane at this point, so I am still being very cautious about any sudden movements of the control surfaces.
Long story short I declared an emergency, and told somebody on the ground to let 911 know there may be an issue with the gear. He got them on the line but they didn’t send anyone out, since to the guy on the ground it looked like the gear was down.
Lincoln Ca is 6000+ feet long, so I had time to touch the gear on the ground and try and get them to lock. And luckily, that is what happened. I touched the left main, raised the plane up a few feet, and I heard the gear lock. A quick look at the indicator lights and I had 3 green. Landed uneventfully and felt very lucky this didn’t turn into a very expensive flight.
So now the question to the group. Does anyone grease the landing gear bolts? Something is binding. Anyone have any experience with this? There are 5 total joints in the rear gear landing mechanism and one of them is binding when there is a rearward force being applied.
I think the best way to test this moving forward is to lower the gear with two people pulling ropes attached to the gear so that I can make sure the gear isn’t binding with a rearward force.
Anyone have any experience, guidance, snide comments?
Jack
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Message: 4
Date: Tue, 30 Sep 2014 00:29:56 -0400
From: "Bob Jackson \(Jax Tech\) via Reflector" <reflector at tvbf.org>
To: "'David Ullman'" <ullman at robustdecisions.com>, "'Velocity Aircraft
Owners and Builders list'" <reflector at tvbf.org>
Subject: Re: REFLECTOR: The use of VG to aid cooling
Message-ID: <012101cfdc67$3155ea10$9401be30$@com>
Content-Type: text/plain; charset="UTF-8"
Wow! Great job on the research and write-up of results, Dave! Definitely worth reading and applying to your own plane. You inspire me to go read one of your books!
We've been using the standard (~1/4" tall) wing and canard VGs in front of our engine NACAs for several years to good effect in lowering our CHTs, but nothing like Dave reports with his super (~2") VGs. I can appreciate and believe the difference he reports and am eager to try them on our plane.
This is a great example of the kind of analysis and communication that makes the Velocity (and Experimental aircraft) community special. Many don't have the background to carry it out, and most of those that do don't have the time, the patience or the kind-heartedness to document and disseminate it back into the community.
Great job on all accounts, Dave!
Thanks,
Bob Jackson
N2XF
XL-RG
PS I'm an Oregon State 1970 grad, Dave. I've been reading your posts over the years and wanting to come by to share stories and insights in the summers when I fly my plane out (from my Orlando home base) to visit Oregon family and 'sight see' the West. Your plane is beautiful and an obvious labor of love. I'll have to try harder next summer. your research is an inspiration, not to mention useful!
-----Original Message-----
From: Reflector [mailto:reflector-bounces at tvbf.org] On Behalf Of David Ullman via Reflector
Sent: Monday, September 29, 2014 8:09 PM
To: reflector at tvbf.org; reflector-request at tvbf.org
Subject: REFLECTOR: The use of VG to aid cooling
My Velocity has always run hot. I have fixed this with the use of Vortex Generators aiding the flow of air into the NACA ducts on top of the fuselage. For a full report go to:
https://davidullman.com/uploads/THE_USE_OF_VORTEX_GENERATORS_TO_ENHANCE_PUSHER_AIRCRAFT_COOLING.pdf
Comments appreciated.
To see recent photos of N444DX hangared in Independence Oregon, go to:
https://davidullman.com/VelocityPhotos.php
David Ullman
David at davidullman.com
_______________________________________________
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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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End of Reflector Digest, Vol 114, Issue 26
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