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Lets look at the specs

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ideaz1(at)sbcglobal.net
Guest

Posted: Tue Nov 25, 2008 12:28 pm Post subject: Lets look at the specs

Per Juan Vega:

 	  Quote: 	
		   pull up the archives, i  brought up the issue of VNE and Max manauvering speeds over one year ago, but  the back room engineers ignored it.

 

 Fly it and follow the  specs.  My guess is the guys flying and that augered in ignored the flight  envelope of the aircraft.  BUILD IT TO PLANS AND FLY IT TO  SPECS.


	


 Ok. The zenith website listssome specs  for the XL and now the 650as:

 Max cruise (at)sea level 138 mph

 75% cruise (at)8000' 160 mph

 VNE  180 mph

 G load (ultimate) +/- 6 g

  

 However when I received my plans the VNE is  listed as 160 mph

  

 this is an excerpt from the specs page:

 Vigorous  performance: 

"My evaluation of cruise speed showed about 140  mph at 2800-2900 rpm, however, the company plans a different prop for Sport  Pilot.

  

 If we look at these numbers and keep in mind that part of  testing a newly built aircraft is to prove these numbers, how many of you feel  safe taking your XL up to 180 mph? 

  

 How about the g load testing. At +/- 6 that should mean a  safe limit of +/- 4 (why doesn't zenith state this) with a 50% margin. would you  feel safe at a +4g steep turn? A typical loop produces about 3.8 to 4  gs How about inverted pushing up at -4g?

  

 How do we decide whether VNE is 160 or 180. if it's 160  what about this 75% cruise of 160.

  

 I'm sorry but something is wrong here and we deserve  factual answers, not this garbage expecting blind faith. I'm building my XL. I  like almost everything about the design, but I will gladly sacrifice an extra  50lbs. of weight making it seriously strong. When the day comes that I fly it  for the first time I want to know without reservation that it isn't coming  apart, period.

  

 Dirk Z 

   [quote][b]

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Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Tue Nov 25, 2008 1:13 pm Post subject: Re: Lets look at the specs

[quote="ideaz1(at)sbcglobal.net"]Per Juan Vega:



 Ok. The zenith website listssome specs  for the XL and now the 650as:

 Max cruise (at)sea level 138 mph

 75% cruise (at)8000' 160 mph

 VNE  180 mph

 G load (ultimate) +/- 6 g

  

 However when I received my plans the VNE is  listed as 160 mph

  

 this is an excerpt from the specs page:

 Vigorous  performance: 

"My evaluation of cruise speed showed about 140  mph at 2800-2900 rpm, however, the company plans a different prop for Sport  Pilot.

  

 If we look at these numbers and keep in mind that part of  testing a newly built aircraft is to prove these numbers, how many of you feel  safe taking your XL up to 180 mph? 

  

 How about the g load testing. At +/- 6 that should mean a  safe limit of +/- 4 (why doesn't zenith state this) with a 50% margin. would you  feel safe at a +4g steep turn? A typical loop produces about 3.8 to 4  gs How about inverted pushing up at -4g?

  

 How do we decide whether VNE is 160 or 180. if it's 160  what about this 75% cruise of 160.

  

 I'm sorry but something is wrong here and we deserve  factual answers, not this garbage expecting blind faith. I'm building my XL. I  like almost everything about the design, but I will gladly sacrifice an extra  50lbs. of weight making it seriously strong. When the day comes that I fly it  for the first time I want to know without reservation that it isn't coming  apart, period.

  

 Dirk Z 

    	  Quote: 	
		  [b] 	




That 160 (at) 8000' is TAS not IAS.



Ultimate means Ultimate 



If you want factual answers regarding the accidents then you are going to have to wait until the FAA and NTSB finish the reports and then the answers still might not be there.



Even in certified aircraft there are accidents that don't get fully explained. In our situation there may not be a design issue that can be singled out. It might well be a repeatable building issue of the type that will be made by one out of x number of builders and it is at a point where the evidence of it doesn't remain after a crash. It all boils down to the fact that the FAA/NTSB/some random European aviation agency might not have an answer.



There is one FACT that we do know. There are lots of 601XLs out there flying there little hearts out and hundreds of them have not had a problem.

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_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

amyvega2005(at)earthlink.
Guest

Posted: Tue Nov 25, 2008 1:49 pm Post subject: Lets look at the specs

Gig, the big number everyone keeps missing,  is Max manauvering- only 103.



You cannot yank and bank at full gross over the Max manauvering.  The rest is moot. G load is utility at predetermine weights again not an ecuse to fly at max speed at Max load and do 6 gs.

There are alot of short time piloits on here that I think fall in the trap thinking great 6 gs max load 1320 two dudes and full fuel , lets yank and bank.  There are quite a few 601s flying and someone is bound to 1- do a crap job of keeping the mainentance up (cable tension and torquing)

  2- build not to specs.

  3- fly out of specs.



I gues what I am saying is build you plane to specs, and fly it to specs, and make sure you know the real limitations (e.i max gross at each speed factor).

EVEN AN EXTRA 300 L WHICH I FLY HAS A WEIGHT LIMIT AND FUEL LIMT FOR YANKING AND BANKING.

No conspiracies here in my book.

Lets move on.



Juan



--

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amyvega2005(at)earthlink.
Guest

Posted: Tue Nov 25, 2008 1:51 pm Post subject: Lets look at the specs

Max Manauvering Speed is 103mph IAS. This is a differnt number than Vne, 



everyone keeps missing that, i dont know why. There rest is moot.  



Juan



--

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bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Tue Nov 25, 2008 1:52 pm Post subject: Lets look at the specs

I would feel quite save flying my 601 XL to 180 mph or pulling 4 Gs at  

gross weight. I've done that in phase 1 testing. I've never pulled -4  

gs, mainly because I don't have inverted fuel or oil systems installed  

and don't particularly like standing on my head. The way the wing  

attachments are designed, if they will take +4 g, there's no reason  

they won't take -4. I don't have a G meter installed now so I would be  

leery doing high G maneuvers, but pushing it to Vne in smooth air  

wouldn't worry me much.



Vne is stated in CAS. When somebody states 75% cruise speed at 8,000  

feet, you can assume they are talking about TAS. Under standard  

conditions, 160 mph TAS at 8000 feet equates to 138 mph CAS, so you  

are still a long way from the 160 mph Vne.



On Nov 25, 2008, at 3:18 PM, Dirk Zahtilla wrote:



 	  Quote: 	
		  

 Ok. The zenith website listssome specs for the XL and now the 650as:

 Max cruise (at)sea level 138 mph

 75% cruise (at)8000' 160 mph

 VNE  180 mph

 G load (ultimate) +/- 6 g



 However when I received my plans the VNE is listed as 160 mph



 this is an excerpt from the specs page:

 Vigorous performance:

 "My evaluation of cruise speed showed about 140 mph at 2800-2900  

 rpm, however, the company plans a different prop for Sport Pilot.



 If we look at these numbers and keep in mind that part of testing a  

 newly built aircraft is to prove these numbers, how many of you feel  

 safe taking your XL up to 180 mph?



 How about the g load testing. At +/- 6 that should mean a safe limit  

 of +/- 4 (why doesn't zenith state this) with a 50% margin. would  

 you feel safe at a +4g steep turn? A typical loop produces about 3.8  

 to 4 gs How about inverted pushing up at -4g?



 How do we decide whether VNE is 160 or 180. if it's 160 what about  

 this 75% cruise of 160.



 I'm sorry but something is wrong here and we deserve factual  

 answers, not this garbage expecting blind faith. I'm building my XL.  

 I like almost everything about the design, but I will gladly  

 sacrifice an extra 50lbs. of weight making it seriously strong. When  

 the day comes that I fly it for the first time I want to know  

 without reservation that it isn't coming apart, period.



 Dirk Z

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_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

hills(at)sunflower.com
Guest

Posted: Tue Nov 25, 2008 5:02 pm Post subject: Lets look at the specs

Howdy all,  

   

I called Zenith a year back to ask about how they determine the vne of their planes. I was told that the speed assigned was the speed that the   

plane has been tested to in flight (at sea level), and not an actual “failure speed”, which they don’t have a way of determining and don’t test too.  

   

Also, regarding the 6g design load, both Zenith and Sonex told me the same thing, the wings on the HD and the Sonex are designed to an ultimate of 9 g’s ,   

So technically they are aerobatic category stressed, but for legal reasons they don’t state this in writing as they don’t want folks doing aerobatic maneuvers in them.  

Note:  The HD does stand for Heavy Duty.  

   

I register my 601 HDS as “Utility” class after I swapped out the engine.  

   

Roger  

         

  

From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Dirk Zahtilla

 Sent: Tuesday, November 25, 2008 2:19 PM

 To: zenith-list(at)matronics.com

 Subject: Lets look at the specs  

  

     

   

    

Per Juan Vega:

 > pull up the archives, i brought up the issue of VNE and Max manauvering speeds over one year ago, but the back room engineers ignored it.

 > 

 > Fly it and follow the specs.  My guess is the guys flying and that augered in ignored the flight envelope of the aircraft.  BUILD IT TO PLANS AND FLY IT TO SPECS.  

    

Ok. The zenith website listssome specs for the XL and now the 650as:  

    

Max cruise (at)sea level 138 mph  

    

75% cruise (at)8000' 160 mph  

    

VNE  180 mph  

    

G load (ultimate) +/- 6 g  

    

   

    

[i]However [/i]when I received my plans the VNE is listed as 160 mph  

    

   

    

this is an excerpt from the specs page:  

    

[b]Vigorous performance[/b]: 

 "My evaluation of cruise speed showed about 140 mph at 2800-2900 rpm, however, the company plans a different prop for Sport Pilot.  

    

   

    

If we look at these numbers and keep in mind that part of testing a newly built aircraft is to prove these numbers, how many of you feel safe taking your XL up to 180 mph?   

    

   

    

How about the g load testing. At +/- 6 that should mean a safe limit of +/- 4 (why doesn't zenith state this) with a 50% margin. would you feel safe at a +4g steep turn? A typical loop produces about 3.8 to 4 gs How about inverted pushing up at -4g?  

    

   

    

How do we decide whether VNE is 160 or 180. if it's 160 what about this 75% cruise of 160.  

    

   

    

I'm sorry but something is wrong here and we deserve factual answers, not this garbage expecting blind faith. I'm building my XL. I like almost everything about the design, but I will gladly sacrifice an extra 50lbs. of weight making it seriously strong. When the day comes that I fly it for the first time I want to know without reservation that it isn't coming apart, period.  

    

   

    

Dirk Z   

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Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Wed Nov 26, 2008 7:15 am Post subject: Re: Lets look at the specs

 	  hills(at)sunflower.com wrote: 	
		  Howdy all,  

   

I called Zenith a year back to ask about how they determine the vne of their planes. I was told that the speed assigned was the speed that the   

plane has been tested to in flight (at sea level), and not an actual “failure speed”, which they don’t have a way of determining and don’t test too.  

   

Also, regarding the 6g design load, both Zenith and Sonex told me the same thing, the wings on the HD and the Sonex are designed to an ultimate of 9 g’s ,   

So technically they are aerobatic category stressed, but for legal reasons they don’t state this in writing as they don’t want folks doing aerobatic maneuvers in them.  

Note:  The HD does stand for Heavy Duty.  

   

I register my 601 HDS as “Utility” class after I swapped out the engine.  

   

Roger  

         

  	




While you may have written Utility some where on the registration I doubt the FAA noticed or cared. Utility class is a Part 23 thing that really effects  EX-HB not a bit.



Just writing utility on the registration doesn't make the plane any stronger.

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_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

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