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Dive to Vne
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MJKTuck(at)cs.com
Guest

Posted: Mon Sep 17, 2007 5:42 pm Post subject: Dive to Vne

Hi Guys,



The 'Dive to Vne' as part of the UK annual inspection was mentioned again.



In my mind Vne is a maximum design speed for the aircraft, first 

calculated and then demonstrated by the manufacturer (probably with some 

margin) as part of the 'proof of design' test program. It is a test that 

takes the airframe close to the outer edge of the envelope and I don't 

think one to be undertaken lightly particularly by your average private 

pilot.



The test has two possible outcomes and to me a positive result is not 

worth the risk of the alternative.



Is there anyway the PFA can persuade the CAA to rethink the need for 

this test as part of an annual check - or at least set some standards as 

to who can perform the test, no passengers, entry and exit altitudes, 

wearing of helmet/parachute in case the test proves negative, etc.



Maybe a requirement to dive to 90% of Vne would be a satisfactory 

compromise?



Regards,

Martin Tuck

N152MT

Wichita, Kansas

ami(at)mcfadyean.freeserv
Guest

Posted: Tue Sep 18, 2007 12:20 am Post subject: Dive to Vne

Martin,

I agree. And it's the reason I don't want to upgrade to 1370lbs, because the 

Vne test only has to be then done at 150kts. Although my particular aircraft 

was Permit-limited to 155kts when first built and therefore originally 

tested at that speed.



Duncan McF

do not archive

---

carl(at)flyers.freeserve.
Guest

Posted: Tue Sep 18, 2007 1:34 am Post subject: Dive to Vne

I suspect that those in the know would say that VNE+ dives are nothing to be 

worried about. After all the aircraft is supposed to be stressed to about 

+5g.



I think that a parachute would be a sensible precaution though I dont know 

how easy it would be to wear one (possibly with the cushions removed). 

Personally I have always had a "professional" pilot accompany me when I did 

the annual flight test. I suspect it is the way the VNE dive is performed 

that is crucial.



There were several instances of the wings becoming dislodged during the 

testing of the original Europa and no doubt due to the experience of the 

test pilots, no one got hurt.



Perhaps someone could look into the possibility of mounting a ballistic 

recovery system in the passenger seat (for the duration of the flight test). 

If someone was able to design a universal fit for kitplanes I suspect there 

would be a good demand for them - subject to cost of course.



Carl Pattinson

G-LABS

---

willie.harrison(at)tinyon
Guest

Posted: Tue Sep 18, 2007 2:37 am Post subject: Dive to Vne

It's presumably not vne itself which creates the main stress, but the  

combination of g pulled by the pilot (can be airspeed-dependent if  

the pilot is not super careful) and g generated by rough air (always  

dependent on airspeed). Can't help wondering what g loadings the  

crash aircraft experienced that day. Has anyone got any info on the  

rumour about the GPS having been interrogated during the investigation?



I share the doubts expressed about the real value of repeating the  

vne test every year.  My own Permit expires every January which means  

that I am typically looking for a calm day in the middle of Winter  

(note for US cousins - Winter in the UK usually means crappy weather,  

low cloud, etc)  with the usual anxiety about the expiry deadline  

looming. Maybe some folk are tempted to do the test in rougher  

weather than they should. Maybe some are also tempted to do the test  

from a lower cloudbase than they should, leaving less height to  

recover and therefore the need to pull more g...? It makes you wonder.



Willie Harrison

G-BZNY



On 18 Sep 2007, at 10:33, Carl Pattinson wrote:



[quote] 

 <carl(at)flyers.freeserve.co.uk>



 I suspect that those in the know would say that VNE+ dives are  

 nothing to be worried about. After all the aircraft is supposed to  

 be stressed to about +5g.



 I think that a parachute would be a sensible precaution though I  

 dont know how easy it would be to wear one (possibly with the  

 cushions removed). Personally I have always had a "professional"  

 pilot accompany me when I did the annual flight test. I suspect it  

 is the way the VNE dive is performed that is crucial.



 There were several instances of the wings becoming dislodged during  

 the testing of the original Europa and no doubt due to the  

 experience of the test pilots, no one got hurt.



 Perhaps someone could look into the possibility of mounting a  

 ballistic recovery system in the passenger seat (for the duration  

 of the flight test). If someone was able to design a universal fit  

 for kitplanes I suspect there would be a good demand for them -  

 subject to cost of course.



 Carl Pattinson

 G-LABS

 ---

rampil

Joined: 04 May 2007
Posts: 870

Posted: Tue Sep 18, 2007 7:11 am Post subject: Re: Dive to Vne

Vne is actually 90% of the true max rated speed Vdive.

Pete Clarke actually tested Vd as required.  It is simply a

convention that us unwashed masses do not cross the 90% Vd line



Too many flight instructors and pilot texts over simplify the

structural issues



If your plane is built to spec, there should be no issue in flying at

Vne in calm air.  Why the PFA wants you to do this annually escapes

me, but it is safe.

_________________
Ira N224XS

ami(at)mcfadyean.freeserv
Guest

Posted: Tue Sep 18, 2007 11:40 am Post subject: Dive to Vne

<<Why the PFA wants you to do this annually escapes

 	  Quote: 	
		   me, >>


	


To check that it is safe!



DuncanMcf

do not archive

---

karelvranken(at)hotmail.c
Guest

Posted: Tue Sep 18, 2007 1:04 pm Post subject: Dive to Vne

William and all,

Vne has not directly a relation with pulling g's. You never make high speed 

in rough air. To catch up speed you have to dive. This doesn't mean 

vertical. You do it smoothly while observing your RPM and intake manifold 

pressure. Don't overboost your engine. The Europa is as fast as you want 

since the big problem was solved with the tie bar. The big problem was the 

displacement of the lift point forwards with higher speeds and caused the 

wings to tend forwards and bend the spars. When I purchased the Europa in 

1999 the tie bar was standard and I was happy with this solution. During the 

test period a friend of mine was filming my passages over the airfield of 

Sedan in France. In one of the low passes I observed an IAS of 180 knots 

without any difference of those below Vne. My conclusion is: don't be afraid 

of Vne, accept it.

Best regards,

Karel Vranken

---

Fergus Kyle

Joined: 03 Jun 2007
Posts: 291
Location: Burlington ON Canada

Posted: Wed Sep 19, 2007 7:53 am Post subject: Dive to Vne

"<<Why the PFA wants you to do this annually escapes me, >>



To check that it is safe!        DuncanMcf "



Duncan, I admire their interest, but it DOES incur two thoughts:



[1]    If they are interested, whu don't THEY do it? I would be prepared to

accept an apology if it splats all over Cheshire, and



[2]    What is the result of discovering it isn't safe? Back to the drawing

board?



Wouldn't that reduce medical practice to striking the temple with bigger

hammers to establish good bone structure?



Cheers, Ferg

wdaniell(at)etb.net.co
Guest

Posted: Wed Sep 19, 2007 8:24 am Post subject: Dive to Vne

2 was going to be my question...



High and with a parachute I think... or is there some other way of testing

this like the static testing on someone's website (can't remember where)

with the bags of cement on the upturned wings.



Will



--

ptag.dev(at)tiscali.co.uk
Guest

Posted: Wed Sep 19, 2007 9:01 am Post subject: Dive to Vne

"Tut Tut" Ferg .....now that really is "agricultural" thinking!



I will say however there are some damn fine engineers who commenced

their active life on farms getting the rudiments of engineering

experience prior to graduating to more sophisticated engineering later

like planting seeds, they need a good foundation!



BTW.....



It is necessary to be at MTOW on take off for these tests and they do

advise to pull out gently and be sure to not exceed the Vne and not to

overspeed the engine ...oh! and to remember to try small manoeuvres

whilst doing it and report any shortcomings !!!!!!

Regards 

Bob H 



Do not archive.....



Robt.C.Harrison

--

kheindl(at)msn.com
Guest

Posted: Wed Sep 19, 2007 9:36 am Post subject: Dive to Vne

And what about the maximum +- g. How come the PFA don't need to have that 

tested ? Shouldn't we pull maximum g at VNE and at MTOW, and if nothing has 

fallen off, then you are good for another year.



Karl



From: "R.C.Harrison" <ptag.dev(at)tiscali.co.uk>

Reply-To: europa-list(at)matronics.com

To: <europa-list(at)matronics.com>

Subject: RE: Dive to Vne

Date: Wed, 19 Sep 2007 18:01:17 +0100

[quote]



"Tut Tut" Ferg .....now that really is "agricultural" thinking!



I will say however there are some damn fine engineers who commenced

their active life on farms getting the rudiments of engineering

experience prior to graduating to more sophisticated engineering later

like planting seeds, they need a good foundation!



BTW.....



It is necessary to be at MTOW on take off for these tests and they do

advise to pull out gently and be sure to not exceed the Vne and not to

overspeed the engine ...oh! and to remember to try small manoeuvres

whilst doing it and report any shortcomings !!!!!!

Regards

Bob H



Do not archive.....



Robt.C.Harrison

--

Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Wed Sep 19, 2007 10:14 am Post subject: Re: Dive to Vne

What is bizarre about the PFA's vne dive requirement is that if the small print on the the permit renewal form is true, the permit renewal will fail to be accepted if you admit to either exceeding vne or failing to reach vne. Not a lot of margin for error there.  I think that says something about the PFA's confidence in our piloting skills and the accuracy of our speedos.



I wonder how many Europa operators know what the position error of their ASI is at 150+ knots?



Which begs the question, why isn't vne specified as a RAS rather than an IAS because the IAS could be way out due to instrument and position errors? I think this question may have been asked before, sorry for the repeat.



Mark

josok-e(at)ukolo.fi
Guest

Posted: Wed Sep 19, 2007 10:39 am Post subject: Dive to Vne

There are at least 3 types of limits. 

Calculated limits, Prooven limits and PFA limits. 

The calculated limits, which include prooven and tested safety margins, lead to testing, and if nothing breaks, flutters or otherwise falls apart, we have prooven limits. Then the PFA comes along and add their own safety factor on the calculated and prooven limits. I have not been able to find any justification for that PFA safety factor, other then the general fit-all: Amateur builders make mistakes. How on earth the PFA can stick a number to these mistakes i do not understand. 

All in all: Diving to PFA-Vne should be absolutely safe, it's some 20 knots slower then the calculated an prooven Vne. The Pfa knows it's safe, because they did the bad builder calculation! 

Is the same bad-builder safety margin enforced on glasairs and vans and the like? Are they to do that Vne dive, while their Vne is probably for real?



Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

rampil

Joined: 04 May 2007
Posts: 870

Posted: Wed Sep 19, 2007 12:15 pm Post subject: Re: Dive to Vne

I like Ferg's analogy to destructive skull testing!



Despite being an engineer in former life, I still don't get it.

Do we require testing of homebuilt sailboats to hull speed

annually?  How many green pilots will die from misadventure near

Vd relative to the number weak wings destructively detected?

(I know I have a thick skull, bring a bigger hammer Ferg)

_________________
Ira N224XS

fklein(at)orcasonline.com
Guest

Posted: Wed Sep 19, 2007 12:38 pm Post subject: Dive to Vne

Would that there was some way to filter this thread so that wives and 

significant others and those faint of heart would not have access to 

it...(sigh!)



Fred



do not archive

-- 

This message has been scanned for viruses and

dangerous content by MailScanner, and is

believed to be clean.

UVTReith(at)aol.com
Guest

Posted: Wed Sep 19, 2007 1:36 pm Post subject: Dive to Vne

Here in Germany we do not do that Vne Dive Test, we are making the static  wing load test with maximum 1.350 kg laod on each wing (upside down). On the  tailwing we put 100 kg on one side and 150 kg on the other side and swap that  then.

  

 This is a requirement from the OUV (the German PFA).

  

  

 Bruno

  

     [quote][b]

tony.bale(at)virgin.net
Guest

Posted: Wed Sep 19, 2007 1:43 pm Post subject: Dive to Vne

All the correspondence on "dive to vne" has been quite interesting. But

having done the last two annual flight tests on our XS mono including the

vne test, the term dive suggests (to me anyway) everything firewalled and

point the nose at terra firma. 



In reality it is nothing like that, I accept most - including our aircraft,

have over reading ASI's (can't remember what the flight test results were)

but with 5400 rpm and probably 25"/26" map the actual nose down attitude is

not very steep at all. It goes without saying this is commenced at high

level on a smooth day, acceleration is strictly limited, the controls are

only moved very smoothly and only to restriced amounts (never need much

deflection anyway !). As an indicator of the scale of the test, our

straight and level speed at full throttle and 5400 rpm is the thick end of

150 knots. (and I bet the turbo boys can see mid to high 150's if they try).



As a point of comparison, with Airmaster cruise setting, and 25" map,

straight and level at circa 2000 ft we indicate 128 Kts +/- (just below the

yellow). Having flown in formation with an Arrow and RV9, our ASI's at this

cruise all read within one or two knots of each other.



My two penny worth anyway.



ATB



Tony.



Original Message:

-----------------

From: rampil ira.rampil(at)gmail.com

Date: Wed, 19 Sep 2007 13:15:11 -0700

To: europa-list(at)matronics.com

Subject: Re: Dive to Vne




I like Ferg's analogy to destructive skull testing!



Despite being an engineer in former life, I still don't get it.

Do we require testing of homebuilt sailboats to hull speed

annually?  How many green pilots will die from misadventure near

Vd relative to the number weak wings destructively detected?

(I know I have a thick skull, bring a bigger hammer Ferg)



--------

Ira N224XS





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=135336#135336





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wdaniell(at)etb.net.co
Guest

Posted: Wed Sep 19, 2007 6:17 pm Post subject: Dive to Vne

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of UVTReith(at)aol.com

 Sent: Wednesday, September 19, 2007 16:35

 To: europa-list(at)matronics.com

 Subject: Re: Dive to Vne  

Here in Germany we do not do that Vne Dive Test, we are making the static wing load test with maximum 1.350 kg laod on each wing (upside down). On the tailwing we put 100 kg on one side and 150 kg on the other side and swap that then.  

This is a requirement from the OUV (the German PFA).  

Bruno  

   	  Quote: 	
		    http://www.matronics.com/Navigator?Europa-List 	
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No virus found in this incoming message.

 9/18/2007 11:53  

  9/18/2007 11:53

    [quote][b]

wdaniell(at)etb.net.co
Guest

Posted: Wed Sep 19, 2007 6:17 pm Post subject: Dive to Vne

Forgive my ignorance but why 1350kg…?  

Will  

       

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of UVTReith(at)aol.com

 Sent: Wednesday, September 19, 2007 16:35

 To: europa-list(at)matronics.com

 Subject: Re: Dive to Vne  

  

  

     

Here in Germany we do not do that Vne Dive Test, we are making the static wing load test with maximum 1.350 kg laod on each wing (upside down). On the tailwing we put 100 kg on one side and 150 kg on the other side and swap that then.  

    

   

    

This is a requirement from the OUV (the German PFA).  

    

   

    

   

    

Bruno  

    

   

   	  Quote: 	
		    http://www.matronics.com/Navigator?Europa-List 	
0 	  Quote: 	
		   	
1 	  Quote: 	
		   	
2 	  Quote: 	
		   	
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No virus found in this incoming message.

 9/18/2007 11:53  

     

  9/18/2007 11:53

    [quote][b]

M.Grass(at)comcast.net
Guest

Posted: Wed Sep 19, 2007 8:08 pm Post subject: Dive to Vne

William,

  

 If you do the math:

 2 times 1350Kg = 2700 kg or around  5940pounds

  

 This would be about the designed max +3.8 G as  specified by Europa plus about a 15 % safety factor

  

  

 Just guessing 

  

 Michael Grass

  

 ---

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