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In-flight opening of front hinged canopy

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psm(at)att.net
Guest

Posted: Sat Jan 10, 2009 4:56 pm Post subject: In-flight opening of front hinged canopy

OK folks, lets play nice.



 I think there is no way anyone can be sure the problems experienced with XLs had anything to do with the pilot's skill (except for the new Sport Pilot who departed the airport, and shortly thereafter the world, in IMC).  



 Similarly, I can tell you that even the best engineers make mistakes.  What makes a world class engineer different from the average ones is a thorough review of everything several times to catch those initial mistakes before anyone else sees them.  Even then the designs are tested using independent methods to confirm the last mistakes have been eliminated.



 Even though I feel I am a bit out of place myself for saying so, I still think we are starting to get a little too personal in our comments about the skills of pilots and engineers.



 Paul

 XL getting close

 do not archive



 



 At 03:48 PM 1/10/2009, you wrote:



 [quote]I thoroughly resent the implication that I crashed because of a lack of skill when the canopy of the airplane I was flying came open.  The other pilot in the airplane was a CFII.  Surely he didn't lack adequate skill. [b]

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chris Sinfield

Joined: 28 Nov 2006
Posts: 270
Location: Sydney Australia

Posted: Sat Jan 10, 2009 6:25 pm Post subject: Re: In-flight opening of front hinged canopy

Sabrina and others,

Whilst a good idea in concept the reality I think would not work for the following reasons:

1 would the canopy miss or take out the fin/ rudder?

2 would you be able to take your hands off the controls that you are fighting to pull the lever/ pins?

 

although more testing would need to be carried out its not a bad Idea if we can work out the issues.



Remember 2 things.. there are photos of the XL flying with the canopy open. So it will fly, given the right combination of factors( without the right combinations of Airspeed/ throttle/ angle of attack it wont fly and thats a fact .. 



So what are these combinationss?? sounds like a summer research  job for an up and coming Aero Engineer  and test pilot  and  test plane ?? and if you are not any of these types, "don't try this at home " 

Chris

Sydney

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Last edited by chris Sinfield on Sat Jan 10, 2009 8:38 pm; edited 1 time in total

psm(at)att.net
Guest

Posted: Sat Jan 10, 2009 6:46 pm Post subject: In-flight opening of front hinged canopy

Hi Sabrina,



I don't know if I am the Paul you meant in your question, but I will 

be glad to try to answer it.



The answer is a great big "It Depends".



I feel the biggest problem with the front hinged canopy is it doesn't 

allow you to exit the plane in flight.  This is not something you 

would really want to do unless the wings fell off or some similar event.



Some sort of canopy release that ejects the canopy in flight might 

allow you to have a chance to survive a structural failure.  It 

probably will kill you anyway, but it might actually give a small 

percentage chance of survival.  I would prefer to have this feature 

for initial flight testing and also wear a parachute for that testing.



On the other hand, the chances of successfully getting out of a 

broken plane and coming down with a parachute are so small that it 

probably isn't worth the effort.  Even in the USAF where they have 

fancy ejection seats and automatic parachutes the survival rate for 

emergency ejections is around 50%.  That is just the survival rate, 

not the chances of getting out without a serious injury - which are 

just about zero.



So, if you are a teenager who expects to live forever and get 

married, have kids, and live happily ever after, then perhaps a 

canopy release is justified.  On the other hand, if you are a retired 

old guy who knows he won't live forever anyway and figures the odds 

of a structural failure are almost zero anyway, then it is not 

justified.  At some point you have to reach the conclusion that you 

will certainly die some way or another and a plane crash is one of 

the best ways to go.



Of course, that is just my opinion.



Paul

XL getting close

do not archive



At 05:37 PM 1/10/2009, you wrote:

 	  Quote: 	
		  Paul, all...



What do you think about an XL canopy that can be ejected?



Is it needed?



The mod costs less than $40  (two MS17985-414 quick release pins and 

one foot of 4130 square tubing)  but the pair of goggles needed, 

just in case, cost about $30 each for a total of $100 and 14 ounces 

of added weight, total.

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chris Sinfield

Joined: 28 Nov 2006
Posts: 270
Location: Sydney Australia

Posted: Sat Jan 10, 2009 8:36 pm Post subject: Re: In-flight opening of front hinged canopy

OK 2 things 

1. by all means release the canopy prior to impact in an out landing  BUT ONLY IF YOU HAVE A STRAP/ROPE STOPPING IT FROM RISING.



Jay has a great design.. our XLs in Australia all have to have such a strap/ rope  with sailing clete preventing it from rising more than 2 inches.. also helps to close the canopy when sitting in the plane, also a wind stopper with the canopy open on the ground.



2 the canopy is so thin that it can be broken with the hand, head if you have crashed. Make sure you are strapped in and your head set does not come close to the roof when in flight and in turbulence. (dont ask) 



I will add that due to Jays experience with the canopy open  we have all become more aware now of what to do if it ever comes open on me. I owe you a beer for the newfound knowledge.  Now for the person who had the canopy open and flying pictures, can he post the airspeed/ power settings?? AMD XL POH as 60 knots  and about 1 foot raised how did they come up with this did they  test this? why re invent the wheel if this is a tested statement??



Chris

Sydney



I have kept the older canopy latches as my POH says to fly and land not try to open the other latch.

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psm(at)att.net
Guest

Posted: Wed Jan 14, 2009 9:37 am Post subject: In-flight opening of front hinged canopy

Hi Sabrina,



In my case, I left a little slack in the release cables.  There is 

still plenty of movement when you rotate the control knob to release 

both latches, but it isn't so tight as to do the nasty stuff you talked about.



I also got lucky with the placement of the rotating knob for the 

release.  It fit kind-of tight so when it is nearly closed it takes a 

little extra force to "Click" into place.  That also means it takes 

some extra force to get it started in the latch opening cycle.



Have fun,



Paul



P.S.  Watch out for jumping electrons.

At 08:50 AM 1/14/2009, you wrote:

 	  Quote: 	
		  I would lock one side, leave the other up.  In attempting to lock 

the remaining side the original side would sometimes release due to 

movement of the release cable.   That scared me.

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