---------------------------------------------------------- Zenith601-List Digest Archive --- Total Messages Posted Tue 02/08/11: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:33 PM - Determining Vx (MHerder) 2. 07:15 PM - Re: Determining Vx (Jerry) 3. 08:15 PM - Re: Determining Vx (Terry Phillips) 4. 08:52 PM - Re: Determining Vx (Keith Ashcraft) 5. 10:37 PM - Re: Determining Vx (Terry Phillips) 6. 10:53 PM - Re: Determining Vx (Don Honabach) ________________________________ Message 1 _____________________________________ Time: 06:33:52 PM PST US Subject: Zenith601-List: Determining Vx From: "MHerder" So Vy and best glide are easy to find, and I'm guessing that Vx is about 85% of Vy under "normal" conditions, although Vx=Vy at service ceiling. How does one determine Vx? Any thoughts. Seems to be about 67kts for my bird, so Im guessing Vy is about 57 kts, I'd just like to know how it's determined. -------- One Rivet at a Time! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=330233#330233 ________________________________ Message 2 _____________________________________ Time: 07:15:33 PM PST US From: Jerry Subject: Re: Zenith601-List: Determining Vx Mike, I will take a stab at it. I've been searching for the source of the information, but haven't found it. When doing your rate of climb flight testing (ROC), you end up with the ROC for various airspeeds. These should be put into a spreadsheet and graphed, plotting ROC on the Y-axis and airspeed on the X-axis. Ideally you should get a parabola. The Vy corresponds with the max ROC of the parobola. Vx is determined by extending a line from origin of the graph (0 ROC and 0 AS) so that it is tangent to the parabola. This is usually pretty close to Vy. I also have a 601HDS with a 912S. My Vy was 70mph true airspeed and Vx was 65 mph TAS. This was at 3500 ft on a 95 degree day. I haven't rerun the test since it has been cold. Jerry N316JL, 70 hours ---- MHerder wrote: > > So Vy and best glide are easy to find, and I'm guessing that Vx is about 85% of Vy under "normal" conditions, although Vx=Vy at service ceiling. > > How does one determine Vx? Any thoughts. Seems to be about 67kts for my bird, so Im guessing Vy is about 57 kts, I'd just like to know how it's determined. > > -------- > ________________________________ Message 3 _____________________________________ Time: 08:15:44 PM PST US From: Terry Phillips Subject: Re: Zenith601-List: Determining Vx Mike One of the books on my wish list a couple of years ago was "Flight Testing Homebuilt Aircraft," by Vaughan Askue. My daughter and son-in-law gave me the book for Christmas. I haven't looked at that book much, because my build was interrupted and flight testing is far away. Askue has a detailed procedure for determining best ROC (Vy) as a function of altitude. It looks like a well thought out approach. And, my favorite flight training book, Machado's "Private Pilot Handbook," in chapter 15, suggests a procedure for determining the best angle of climb speed (Vx) from the ROC curves that result from Askue's procedure. You might take a look at those two books. Good luck with your flight testing. Terry At 06:30 PM 2/8/2011 -0800, you wrote: >So Vy and best glide are easy to find, and I'm guessing that Vx is about >85% of Vy under "normal" conditions, although Vx=Vy at service ceiling. > >How does one determine Vx? Any thoughts. Seems to be about 67kts for my >bird, so Im guessing Vy is about 57 kts, I'd just like to know how it's >determined. > >-------- >One Rivet at a Time! > > Terry Phillips ttp44~at~rkymtn.net Corvallis MT ZU-601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail & flaps are done; Upgrading wings & ailerons per the AMD Safety Directive http://www.mykitlog.com/N47TP/ ________________________________ Message 4 _____________________________________ Time: 08:52:41 PM PST US From: Keith Ashcraft Subject: Re: Zenith601-List: Determining Vx Look at the attached file and see if this is what you are looking for. Found it on the EAA.org homebuilders site. Keith CH701 - scratch (working on cabin area) ________________________________ From: MHerder Sent: Tue, February 8, 2011 7:30:47 PM Subject: Zenith601-List: Determining Vx So Vy and best glide are easy to find, and I'm guessing that Vx is about 85% of Vy under "normal" conditions, although Vx=Vy at service ceiling. How does one determine Vx? Any thoughts. Seems to be about 67kts for my bird, so Im guessing Vy is about 57 kts, I'd just like to know how it's determined. -------- One Rivet at a Time! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=330233#330233 Be a PS3 game guru. http://videogames.yahoo.com/platform?platform=120121 ________________________________ Message 5 _____________________________________ Time: 10:37:19 PM PST US From: Terry Phillips Subject: Re: Zenith601-List: Determining Vx Good find, Keith That article only addresses determining Vy. However, it is 1 of a series of about 5 articles. One of the other articles describes the Vx calculation. Kolano appears to confirm Askue's procedure and the Vx determination suggested by Machado. Terry At 08:50 PM 2/8/2011 -0800, you wrote: >Look at the attached file and see if this is what you are looking for. >Found it on the EAA.org homebuilders site. > >Keith >CH701 - scratch (working on cabin area) > > >From: MHerder >To: zenith601-list@matronics.com >Sent: Tue, February 8, 2011 7:30:47 PM >Subject: Zenith601-List: Determining Vx > > >The fish are biting. Terry Phillips ttp44~at~rkymtn.net Corvallis MT ZU-601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail & flaps are done; Upgrading wings & ailerons per the AMD Safety Directive http://www.mykitlog.com/N47TP/ ________________________________ Message 6 _____________________________________ Time: 10:53:52 PM PST US From: Don Honabach Subject: RE: Zenith601-List: Determining Vx If you have a RV builder nearby, there is a nice section in their builder's manual (?) that they get that talks about Vx/Vy and how to get the numbers during your test flights. Don From: owner-zenith601-list-server@matronics.com [mailto:owner-zenith601-lis t-server@matronics.com] On Behalf Of Terry Phillips Sent: Tuesday, February 08, 2011 11:31 PM Subject: Re: Zenith601-List: Determining Vx Good find, Keith That article only addresses determining Vy. However, it is 1 of a series of about 5 articles. One of the other articles describes the Vx calculation. Kolano appears to confirm Askue's procedure and the Vx determination sugges ted by Machado. Terry At 08:50 PM 2/8/2011 -0800, you wrote: Look at the attached file and see if this is what you are looking for. Foun d it on the EAA.org homebuilders site. Keith CH701 - scratch (working on cabin area) From: MHerder > Sent: Tue, February 8, 2011 7:30:47 PM Subject: Zenith601-List: Determining Vx The fish are biting. Terry Phillips ttp44~at~rkymtn.net Corvallis MT ZU-601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail & flaps are done; Upgrading wings & ailerons per the AMD Safety Directive http://www.mykitlog.com/N47TP/ ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message zenith601-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Zenith601-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/zenith601-list Browse Digests http://www.matronics.com/digest/zenith601-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.