---------------------------------------------------------- Pietenpol-List Digest Archive --- Total Messages Posted Thu 08/24/17: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:27 AM - Re: VNE (L. Harris) 2. 08:59 AM - Website down? (Steven Dortch) 3. 12:38 PM - Re: Website down? (Rick) 4. 02:17 PM - Re: Website down? (jarheadpilot82) 5. 09:02 PM - Re: VNE (taildrags) ________________________________ Message 1 _____________________________________ Time: 05:27:01 AM PST US From: "L. Harris" Subject: Re: Pietenpol-List: VNE Thanks for posting. A lot of good speed info. here. Lorenzo ________________________________ From: owner-pietenpol-list-server@matronics.com on behalf of Steven Dortch Sent: Wednesday, August 23, 2017 11:31 PM Subject: Pietenpol-List: VNE Check out this article. http://www.flyingmag.com/technique/proficiency/technicalities-are-you-feeli ng-lucky [http://www.flyingmag.com/sites/flyingmag.com/files/styles/small_1x_/public /import/2010/sites/all/files/_images/201009/FLY0910_tech_674x674.jpg?itok =NSLgN5d6] Technicalities: Are You Feeling Lucky? | Flying Magazine www.flyingmag.com IT HAPPENED LAST MAY, DURING an air race in South Africa. An airplane was d escending toward a turn point in a valley when the pilot of a following air plane saw what ... ________________________________ Message 2 _____________________________________ Time: 08:59:31 AM PST US From: Steven Dortch Subject: Pietenpol-List: Website down? is the Brodhead Pietenpol site down? http://www.pietenpols.org/forum/ -- Blue Skies, Steve D ________________________________ Message 3 _____________________________________ Time: 12:38:46 PM PST US Subject: Re: Pietenpol-List: Website down? From: Rick It's working fine for me Sent from my iPad > On Aug 24, 2017, at 10:58 AM, Steven Dortch wr ote: > > is the Brodhead Pietenpol site down? > http://www.pietenpols.org/forum/ > > -- > Blue Skies, > Steve D ________________________________ Message 4 _____________________________________ Time: 02:17:30 PM PST US Subject: Pietenpol-List: Re: Website down? From: "jarheadpilot82" Worked fine for me as well. It's you Steve. ;0) -------- Semper Fi, Terry Hand Athens, GA Read this topic online here: http://forums.matronics.com/viewtopic.php?p=472149#472149 ________________________________ Message 5 _____________________________________ Time: 09:02:45 PM PST US Subject: Pietenpol-List: Re: VNE From: "taildrags" There is indeed a lot of food for thought in that article. And since I can't stand to read things like this without playing with numbers, I decided to run some numbers for the Air Camper through the formulae that are presented in the article. First, there is the theoretical "design cruising speed" Vc, which, for aircraft with wing loadings of less than 20 pounds per square foot, is stated to be 33 times the square root of the wing loading. The "Improved" Air Camper plans show a span of 29 ft and a chord of 5 ft, which gives 145 sq.ft., and a max gross weight of 1,080 lbs (varies, depending on where you're looking). Resulting wing loading is 7.45 lb/sq.ft., so 33 times the square root of that is 90 KIAS. As the author observes, many airplanes can't actually cruise at this design cruising speed and that's very likely the case for most Air Campers since that translates to almost 104 MPH indicated. But let's continue. The article says that Vc provides the basis for determining the design dive speed Vd, which is 1.4 times Vc or 126 KIAS (146 MPH indicated). Furthermore, the never-exceed speed Vne is nine-tenths of Vd or 113 KIAS (131 MPH indicated). The 1932 plans give a maximum speed Vne of 90 MPH (78 kt). It goes on to say that if the airplane can't achieve its design Vd in flight, then the dive speed actually attained in flight test, Vdf, replaces Vd, and Vne is nine-tenths of that. I would be very curious to know if anyone has ever flight-tested their Air Camper to maximum dive speed, or had one anywhere close to 131 MPH indicated. I have not. Now for the interesting, if somewhat esoteric, part of the discussion. Vne is an indicated airspeed, but the critical *flutter* speed may be a true airspeed and as a result the margin separating Vne from the critical flutter speed gets smaller as you gain altitude because true airspeed increases as the air density decreases, and air density generally decreases with altitude. So for example, if John Dilatush's turbocharged Subaru-powered Air Camper, operating out of his home airport of Salida Colorado (7,523' MSL) is flown at 2500' AGL, it would be at roughly 10,000 MSL. If it were summertime and the OAT were 95F with a relative humidity of 30%, the density altitude would be 14,620'. If he was flying at Vne of 90 MPH (78 KIAS), his TAS would be 97 kt. The article states that the cumulative margin between Vne and critical flutter speed is 33%, so in this (theoretical) case, that would be 26 kt. In the condition described, this airplane could be flying within 7 kt of its critical flutter speed but showing that it had not exceeded the designer's Vne of 90 MPH (78 kt). In the mountains, in the summer, with thermals... could the airplane gain another 7kt on a strong ridge lift or downdraft and hit critical flutter? Does anyone really know how close to actual any of these numbers are? Who developed the formulae and rules of thumb, and how much fluff or slack did they put in the numbers? So numbers exercises aren't just for the fast planes. Even for us low and slow flyers who may never see airspeeds in the triple digits, aerodynamic effects are still in play. No, we're not all flying ticking time bombs here, but since Steve raised the issue by posting the link to the article, I thought I would exercise my calculator to see what the numbers might be for this what-if. I like what the author says: "...if I were to ride a wave to 35,000 feet in a 172, I would not be in a hurry to peg the airspeed at redline on the way back down." I think I would, though! Do you know how COLD it is up there??!! -------- Oscar Zuniga Medford, OR Air Camper NX41CC "Scout" A75 power, 72x36 Culver prop Read this topic online here: http://forums.matronics.com/viewtopic.php?p=472162#472162 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message pietenpol-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Pietenpol-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/pietenpol-list Browse Digests http://www.matronics.com/digest/pietenpol-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.