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james.k.hovis(at)gmail.co
Guest

Posted: Fri May 18, 2007 4:54 am Post subject: Establishing gross weight

A quick (hopefully) education on material properties. Metals when

placed under load will stretch or compress a certain amount

proportional to the load applied. When the load is removed, the metal

will go back to its original shape. This is called elastic

deformation. Increasing loads will stretch or compress the metal

elastically in a linear fashion up to a certain stress level called

the "Yield Point". The stress at this point is "Yield Stress". Loads

applied beyond the yield point will deform the metal plastically,

meaning when such a load is removed, the metal DOES NOT return to its

original shape. This will continue up to a point where the metal will

actually break, the "Ultimate Stress". Look at FAR 23.305, limit loads

(3.8G for Normal cat.)must not permanently deform the structure and

the structure must withstand the ultimate loads (5.7G) for three

seconds without failure (breaking). Therefore, yield stress is often

used at limit load to size the structure. Any loading exceeding the

limit load will deform the structure rendering unuseable, but

hopefully not breaking. However, I don't know what philosophy Van's

used. I assume a very conservative approach.



Kevin H.



On 5/17/07, JSMcGrew(at)aol.com <JSMcGrew(at)aol.com> wrote:

 	  Quote: 	
		  



 Dan,



 I'm only responding because I think builders should think long and hard

 before making the decision to increase Van's recommended limits. I don't

 want to

 see any statistics in our group. The RV-10 was designed to handle 3.8G's

 with

 a  ~1.5 safety margin (~5.7G ultimate). Anything you do beyond the design

 conditions cuts into said safety margin.



 By your argument the C-5 Galaxy with a maximum gross weight of 840,000 lbs

 x

 3.8G's can handle 3,192,000# of load. So when at low fuel weight (374,000#)

 it  should be able to pull 3,192,000# / 374,000# = 8.5 G's. That would be

 something  to see, however, that is simply not the case; it just doesn't

 work that

 way.



 You can justify all you want. I still don't recommend it.



 -Jim



 In a message dated 5/17/2007 12:27:12 P.M. Eastern Daylight Time,

 LloydDR(at)wernerco.com writes:



 We are not talking  safety margins, we are talking an aircraft rated in the

 standard category and  as such will sustain 3.8G's without structural

 failure.

 Nuff said. If the  location of the additional 200 LBS keeps the plane in CG

 than there will not  be an issue in standard flight conditions, what is

 unknown

 is how the plane  will react when the plane is stressed past the max load

 breaking point of  3.8G's x 2700lbs or 10,260LBS total. Then once you get

 past

 this point  there is the safety margin that is built in, but unless you go

 past

 the 10,260  LBS limit then there is nothing new being discovered.



 Dan

 ____________________________________

  From: owner-rv10-list-server(at)matronics.com

 [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of  JSMcGrew(at)aol.com

 Sent: Thursday, May 17, 2007 12:00  PM

 To: rv10-list(at)matronics.com

 Subject: Re:  Establishing gross weight



 The design safety margins are established to account for  variations in

 construction, fatigue, turbulence, variations in piloting,  engineering

 mistakes

 etc. etc., all of which are fairly difficult to  predict when they will

 happen

 or what the effect will be. Furthermore, an  aircraft experiences many

 different stresses during the course of a flight  (besides just holding the

 airplane

 up in level flight). You need a thorough  engineering analysis to understand

 the effects a deviation from  the design conditions will have on the

 airframe in

 various flight  conditions.



 I recommend sticking to Van's established limits (weight limits and all

 others) unless one is willing and capable of performing such an  analysis.



 -Jim McGrew

 40134

 Jim "Scooter"  McGrew

 _http://www.mit.edu/~jsmcgrew_ (http://www.mit.edu/~jsmcgrew)

 In a message dated 5/17/2007 11:35:42 A.M. Eastern Daylight Time,

 LloydDR(at)wernerco.com writes:



 



 Let me clarify my position, Like you  have stated the plane has already

 had a static test of its 2700 lbs,  which means the wing will need to

 support 3.8 times that to be in the  standard category, which means

 theoretically both wings together will  withstand 10,260 lbs and not

 fail. With this being said, it would not be  a long stretch stating that

 an additional 200 pounds in the right  location will not cause an issue

 during normal flight and clear  non-turbulent conditions. I did not state

 that it was a smart thing to do  and go fly in turbulence, what I did

 state was set it high, flight test  it and adjust as necessary.



 Dan N289DT RV10E

 Jim "Scooter"  McGrew

 _http://www.mit.edu/~jsmcgrew_ (http://www.mit.edu/~jsmcgrew)



 ************************************** See what's free at

 http://www.aol.com.

LloydDR(at)wernerco.com
Guest

Posted: Fri May 18, 2007 5:43 am Post subject: Establishing gross weight

Jim

 I agree with you, but if  you read my post I stated that testing of the new weight was a requirement.  Since you bring in the military, lets point this out, the DC3 was designed for  26k lbs, and when it was put into military service as a C-47, the max weight was  increased to 28K, this increased weight was determined acceptable by testing,  and all I am saying is that it is okay to increase the max gross weight and test  to make sure it is ok. Another option in this scenario is that a max takeoff  weight, and a max landing weight be established and a fuel jettison system be  installed, it is routine practice to overload an aircraft, knowing that fuel  burn in flight will allow the aircraft to return within limits, so if Wayne  wanted to he could designate a max takeoff weight that matches his adjusted  gross and then put in the op limitations that when landing it is not to exceed  Vans recommended weight, and this could be accomplished by fuel burn/  jettison.

 The venerable Cessna 172  has had its max weight increased several times during its life, equaling several  hundred pounds and without structural modification. This was accomplished by  continued testing and analyzing the results. This is all I am recommending him  to do.

 We are experimental  builders after all and the purpose is to experiment, if you are not willing to  do that then buy a certified plane and be assured that the plane was tested by  someone else. But if you are wanting to further yourself and your skills, and  learn what testing is about then  buy an experimental and experiment, that  is our right as builders and test pilots.

 Dan

 N289DT RV10E  (Experimenting with an alternative power plant and loving every minute of not  doing what is accepted by Van's, I am such a rebel!)



   From: owner-rv10-list-server(at)matronics.com  [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of  JSMcGrew(at)aol.com

Sent: Thursday, May 17, 2007 4:40  PM

To: rv10-list(at)matronics.com

Subject: Re: RV10-List:  Establishing gross weight

 

   Dan,

  

 I'm only responding because I think builders should think long and hard  before making the decision to increase Van's recommended limits. I don't want to  see any statistics in our group. The RV-10 was designed to handle 3.8G's with a  ~1.5 safety margin (~5.7G ultimate). Anything you do beyond the design  conditions cuts into said safety margin.

  

 By your argument the C-5 Galaxy with a maximum gross weight of 840,000 lbs  x 3.8G's can handle 3,192,000# of load. So when at low fuel weight (374,000#) it  should be able to pull 3,192,000# / 374,000# = 8.5 G's. That would be something  to see, however, that is simply not the case; it just doesn't work that  way.

  

 You can justify all you want. I still don't recommend it.

  

 -Jim

  

 In a message dated 5/17/2007 12:27:12 P.M. Eastern Daylight Time,  LloydDR(at)wernerco.com writes:

  	  Quote: 	
		     We are not talking    safety margins, we are talking an aircraft rated in the standard category and    as such will sustain 3.8G's without structural failure. Nuff said. If the    location of the additional 200 LBS keeps the plane in CG than there will not    be an issue in standard flight conditions, what is unknown is how the plane    will react when the plane is stressed past the max load breaking point of    3.8G's x 2700lbs or 10,260LBS total. Then once you get past this point    there is the safety margin that is built in, but unless you go past the 10,260    LBS limit then there is nothing new being discovered.

    

   Dan



         From: owner-rv10-list-server(at)matronics.com    [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of    JSMcGrew(at)aol.com

Sent: Thursday, May 17, 2007 12:00    PM

To: rv10-list(at)matronics.com

Subject: Re: RV10-List:    Establishing gross weight

   

         The design safety margins are established to account for    variations in construction, fatigue, turbulence, variations in piloting,    engineering mistakes etc. etc., all of which are fairly difficult to    predict when they will happen or what the effect will be. Furthermore, an    aircraft experiences many different stresses during the course of a flight    (besides just holding the airplane up in level flight). You need a thorough    engineering analysis to understand the effects a deviation from    the design conditions will have on the airframe in various flight    conditions.

    

   I recommend sticking to Van's established limits (weight limits and all    others) unless one is willing and capable of performing such an    analysis.

    

   -Jim McGrew

   40134

    

      Jim "Scooter"    McGrew

http://www.mit.edu/~jsmcgrew    



    

   In a message dated 5/17/2007 11:35:42 A.M. Eastern Daylight Time,    LloydDR(at)wernerco.com writes:

    	  Quote: 	
		  -->      RV10-List message posted by: "Lloyd, Daniel R."      <LloydDR(at)wernerco.com>



Let me clarify my position, Like you      have stated the plane has already

had a static test of its 2700 lbs,      which means the wing will need to

support 3.8 times that to be in the      standard category, which means

theoretically both wings together will      withstand 10,260 lbs and not

fail. With this being said, it would not be      a long stretch stating that

an additional 200 pounds in the right      location will not cause an issue

during normal flight and clear      non-turbulent conditions. I did not state

that it was a smart thing to do      and go fly in turbulence, what I did

state was set it high, flight test      it and adjust as necessary.



Dan N289DT RV10E       

	




	


 



  

 Jim "Scooter"  McGrew

http://www.mit.edu/~jsmcgrew  



   See what's free at AOL.com.  

[quote]



href="http://www.matronics.com/Navigator?RV10-List">http://www.matronics.com/Navigator?RV10-List

href="http://forums.matronics.com">http://forums.matronics.com



[b]

LloydDR(at)wernerco.com
Guest

Posted: Fri May 18, 2007 6:01 am Post subject: Establishing gross weight

I agree whole heartedly with this, how do we set it up and  coordinate the effort?

 Dan

 N289DT



   From: owner-rv10-list-server(at)matronics.com  [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Bob  Leffler

Sent: Friday, May 18, 2007 6:39 AM

To:  rv10-list(at)matronics.com

Subject: RE: Establishing gross  weight

 

  

Great  idea! 

  

  

I’m  in………… 

  

At  my point of build, I’m an information sponge on anything  RV-10. 

  

Bob 

  

Do  Not Archive 

    

From:  owner-rv10-list-server(at)matronics.com  [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of John W.  Cox

Sent: Thursday, May 17, 2007 11:01 PM

To:  rv10-list(at)matronics.com

Subject: RE: Establishing gross  weight



 

  

  

Anybody  want to talk about an RV-10 Operator’s Seminar at OSH like Lancair does? So we  can hammer out these issues. 

  

John  Cox 

  

Do not  Archive 

 

[quote]



href="http://www.matronics.com/Navigator?RV10-List">http://www.matronics.com/Navigator?RV10-List

href="http://forums.matronics.com">http://forums.matronics.com



[b]

rvbuilder(at)sausen.net
Guest

Posted: Fri May 18, 2007 6:33 am Post subject: Establishing gross weight

I can see something that starts off very informal until it hit’s a critical mass that we could approach EAA for forum space.  In the mean time I would suggest that someone (JC) starts developing some talking points that seem to be of interest to the list.  We could then convert one of the daily meeting times at Van’s tent to a one hour lunch and learn session someplace that isn’t in use with picnic tables or chairs.  Very much a round table type session unless someone of expertise would have a presentation that they feel would be useful.  

   

Thoughts?

 

   

Michael  

       

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Lloyd, Daniel R.

 Sent: Friday, May 18, 2007 9:01 AM

 To: rv10-list(at)matronics.com

 Subject: RE: Establishing gross weight  

  

  

   

I agree whole heartedly with this, how do we set it up and coordinate the effort?  

Dan  

N289DT  

       

  

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Bob Leffler

 Sent: Friday, May 18, 2007 6:39 AM

 To: rv10-list(at)matronics.com

 Subject: RE: Establishing gross weight  

Great idea!  

   

   

I’m in…………  

   

At my point of build, I’m an information sponge on anything RV-10.  

   

Bob  

   

Do Not Archive  

       

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of John W. Cox

 Sent: Thursday, May 17, 2007 11:01 PM

 To: rv10-list(at)matronics.com

 Subject: RE: Establishing gross weight  

  

  

   

   

Anybody want to talk about an RV-10 Operator’s Seminar at OSH like Lancair does? So we can hammer out these issues.  

   

John Cox  

   

Do not Archive  

   [quote]  href="http://www.matronics.com/Navigator?RV10-List">http://www.matronics.com/Navigator?RV10-Listhref="http://forums.matronics.com">http://forums.matronics.com  ;      - The RV10-List Email Forum -http://www.matronics.bsp;         - NEW MATRONICS WEB FO; http://forums.matronics.com</================== [b]

ScooterF15

Joined: 19 Jun 2006
Posts: 136

Posted: Fri May 18, 2007 6:39 am Post subject: Establishing gross weight

Dan,

  

 Sure. I'm not against modifications, just modifications without proper  testing and analysis. I don't want builders in general to justify modifications  arbitrarily. I certainly don't have anything against you, please don't take my  previous post personally.  I've had a lot of experience in military flying  and engineering and things don't always go optimally. For example I was flying  in a T-38 on an instrument check ride one day in clear VFR and got hit by  turbulence plus minus about 3 G's. I've never been thumped so hard out of the  blue. I hit my head on the canopy and got a splitting headache (that didn't help  the check pilot's attitude either). Think about negative G limits for  the RV-10 as well, they are a lot less. You never know when you might experience  some rough turbulence. I've personally chose to keep the weight limits at  2700. I ended up with a 1570# empty weight and that works out great for useful  load.

  

 I spoke to Ken at Van's about the design process they used. It's really  hard to test and analyze all different possible stresses on an airframe. So, my  understanding is that they did point testing and analysis to ensure certain  conditions were met (like load testing the wing for ultimate loading). Then  designed so that the infinite number of in-between conditions would be met. It's  just hard to be certain you're OK without the know how and resources available  to Van's engineering team, the military, or Cessna etc.

  

 Just food for thought. Good luck and keep building. I hope to see you at a  fly-in in the near future.

  

 -Jim

  

  Jim "Scooter"  McGrew

http://www.mit.edu/~jsmcgrew  



  

  

 In a message dated 5/18/2007 9:45:14 A.M. Eastern Daylight Time,  LloydDR(at)wernerco.com writes:

  	  Quote: 	
		     Jim

   I agree with you, but    if you read my post I stated that testing of the new weight was a requirement.    Since you bring in the military, lets point this out, the DC3 was designed for    26k lbs, and when it was put into military service as a C-47, the max weight    was increased to 28K, this increased weight was determined acceptable by    testing, and all I am saying is that it is okay to increase the max gross    weight and test to make sure it is ok. Another option in this scenario is that    a max takeoff weight, and a max landing weight be established and a fuel    jettison system be installed, it is routine practice to overload an aircraft,    knowing that fuel burn in flight will allow the aircraft to return within    limits, so if Wayne wanted to he could designate a max takeoff weight that    matches his adjusted gross and then put in the op limitations that when    landing it is not to exceed Vans recommended weight, and this could be    accomplished by fuel burn/ jettison.

   The venerable Cessna    172 has had its max weight increased several times during its life, equaling    several hundred pounds and without structural modification. This was    accomplished by continued testing and analyzing the results. This is all I am    recommending him to do.

   We are experimental    builders after all and the purpose is to experiment, if you are not willing to    do that then buy a certified plane and be assured that the plane was tested by    someone else. But if you are wanting to further yourself and your skills, and    learn what testing is about then  buy an experimental and experiment,    that is our right as builders and test pilots.

   Dan

   N289DT RV10E    (Experimenting with an alternative power plant and loving every minute of not    doing what is accepted by Van's, I am such a  rebel!)

	


 



  

  



See what's free at AOL.com. 

  [quote][b]

jesse(at)saintaviation.co
Guest

Posted: Fri May 18, 2007 6:51 am Post subject: Establishing gross weight

Now that’s what this list is for.  What a great exchange of opinions, facts, and ideas on all sides.  

   

Do not archive  

     

Jesse Saint  

Saint Aviation, Inc.  

jesse(at)saintaviation.com (jesse(at)saintaviation.com)  

www.saintaviation.com  

Cell: 352-427-0285  

Fax: 815-377-3694  

  [quote] [b]

John Ackerman

Joined: 19 Jun 2006
Posts: 130
Location: Prescott, AZ

Posted: Fri May 18, 2007 7:36 am Post subject: Establishing gross weight

 	  Quote: 	
		  

With this being said, it would not be a long stretch stating that 

an additional 200 pounds in the right location will not cause an issue 

during normal flight and clear non-turbulent conditions.  



 	


So, among other things, we need to know... What is a "long stretch"? How do we know what a "long stretch" is?



CG aside, what is a "right location" and what is not? How do we know?



 	  Quote: 	
		  ...and clear non-turbulent conditions. I did not state that it was a smart thing to do and go fly in turbulence, what I didstate was set it high, flight test it and adjust as necessary.

 

	


 	  Quote: 	
		  Really and truly, I think the gross weight should be established during the fly-off period. 	




What are we going to find out from a "flight test", assuming, of course that the airplane does not flutter, bend detectably, or come apart?

How do we conduct such a test? How (quantitatively) do you adjust GW based on test results? How do you know the test has not overstressed the airplane already, and thus lowered the allowable weight? I suspect that _at least_ education equivalent to that of a B.S. with an emphasis on structures would be required to take on these issues.



Has anyone tried exiting the 10 while wearing a parachute, even stopped on the ground?



One could make a pretty good argument for _decreasing_ the gross weight that we actually fly to. The reason is that -as far as I know- we have no way to know that our wings are capable of withstanding the same loads as Van's test article - regardless of whether they are slow build or fast build. Likewise, we have no way of knowing by how much they might deviate. My personal approach is to decrease the airspeed rather than the gross weight, though.



 	  Quote: 	
		  We are not talking safety margins, we are talking an aircraft rated in the standard category and as such will sustain 3.8G's without structural failure. Nuff said.

	


No, most assuredly _not_ enough said.



We have some really wide latitude with experimental amateur-built aircraft, and rights that are probably the envy of pilots and builders worldwide. With rights come corresponding responsibilities. I submit that the rights accrue to us as individuals, but the responsibilities are to our passengers, families, ourselves, and the families of anyone who might fly or ride in the aircraft down the line, possibly long after we are gone. Oh, yeah - and to our fellow builders who would share in the effects of any negative result of our actions.



Thanks to Rick for the excellent insurance discussion, and to James Hovis for the continuing  rational, understated engineering perspective.

 [quote][b]

Tim Olson

Joined: 25 Jan 2007
Posts: 2882

Posted: Fri May 18, 2007 7:45 am Post subject: Establishing gross weight

I've just followed the comments on this so far, but I guess I

may as well speak too.



I think:



General builder questions would be well addressed in things

like workshops that already exist at EAA events, and by online

discussions, and by things like the recent workshop held

by David Saylor.  So when it comes to building things, we

can all sit around the campfire and shoot the sh1t all night

long. That would work well.



For general flying skills, I think at present we not only

don't have the critical mass nor the commonality among

airplanes and panels to really go in depth and have an

event that would fit everyone or even draw a huge attendance.

We certainly don't have a critical mass to do anything that

would qualify us for reduced insurance rates as a motivator.



Then, for RV-10 flying skills, nothing really beats a couple

hours with someone like Mike S. or Alex D. to get transition

training.  It's a great place to start.



The gap, as I see it today, is that there are a lot of unique

discussion topics that really could benefit from an hour

(or perhaps much more), where people who are currently flying,

operating, or maintaining the RV-10 could give some great

input as to the many things that you don't get out of the

above.  There are things about how the RV-10 flies, and

things about how you can operate it, about some

maintenance gotchas, and about some things like the the

final stages of pre-first-flight preparation, that really

would be great for just a forum type event.  Perhaps a

bullet-point list could be put together by a few people, or

questions could be provided for a Q&A list, and at OSH

we could set aside some time where 4-10 current RV-10

operators could speak as pseudo-panelists and give their

opinions...even if they don't all agree.  I would be willing

to participate in something of that nature. I also am

quick to point out that while I may have what some would

view as good input to give, I also would not consider myself

an expert, as there are truly very few people who fit that

description.  So just as anything, you'd have to take it

only as my opinion.  There are far too many who speak

as experts without the qualifications, and I don't want

anyone to mistake me as one of those.



Also, some of the types of questions that could be

answered well by a panel of people are what types of

impressions they have for the need for certain equipment,

such as:  Rudder Trim, Yaw Dampners, Autopilot features,

Elevator trim, lighting options, and the many things that

people question whether or not they want to add them to

their plane.  Those are things that it would be nice

to hear from multiple flying -10 owners and get more

of a flowing conversation idea of what they all think.



So depending on what y'all say you want, I'd probably be

happy to participate. Ideally, everyone would take a demo

flight with me or someone else, (which PLEASE, this won't

be happening at OSH), because I usually speak at length

about some of these things during the demo flights I give.

It's the best way to really get things pointed out for you

and then let you see first-hand, in-flight, and form

your own opinion.



If we do this at OSH, I think we should just do it at

a place like RV-10 HQ, where we probably will already

have some chairs, and do it on some mid-morning or mid-afternoon

timeframe, perhaps on a day like Tuesday/Wed/or Thurs.

It could even be done twice, with the same agenda, so that

as many builders as possible could participate.



Let's see if there's continuing interest.  If you like

the theory above, then shortly we should start

off-line gathering a list of topics and questions, and

we can start getting a list of people to speak.  I'm sure

we could talk Vic, who's also a DAR, into speaking too,

as long as his schedule allows.



Tim Olson - RV-10 N104CD - Flying

do not archive

RV Builder (Michael Sausen) wrote:

 	  Quote: 	
		     I can see something that starts off very informal until it hit’s a 

 critical mass that we could approach EAA for forum space.  In the mean 

 time I would suggest that someone (JC) starts developing some talking 

 points that seem to be of interest to the list.  We could then convert 

 one of the daily meeting times at Van’s tent to a one hour lunch and 

 learn session someplace that isn’t in use with picnic tables or chairs. 

  Very much a round table type session unless someone of expertise would 

 have a presentation that they feel would be useful.

 

  

 

 Thoughts?

 

 Michael

LloydDR(at)wernerco.com
Guest

Posted: Fri May 18, 2007 8:20 am Post subject: Establishing gross weight

The beauty of the experimental category is that each of us  gets to determine what is right and wrong in the way of testing. With that being  said the correct amount of testing is what makes you as the builder satisfied as  to the safety of the aircraft and what you determine the max allowable weight to  be. Once again it is up to the builder to set these parameters, whether they  actually test the aircraft themselves or pay to have the aircraft tested, it is  the builder that is ultimately responsible for this, regardless of what the  builder community feels they can not stop an individual from doing what they  want as long as it meets the regulation requirements set by the FAA. As for a  responsibility to others who ride in the plane, there is a placard that is  required that says it does not meet the standards and as such they need to make  the decision before they get in to determine whether they trust the builder or  not, and whether they are willing to put their life on the line based on that  trust. 

 It is all about personal responsibility, not what others  place on you, and you as the builder need to determine if it is safe or  not.

 IMHO (my opinion) many people are willing to fly their  certified aircraft over gross, and as such they would be willing to fly their  experimental over gross, regardless of what the listed gross was. So,once again  IMHO the placard is there and it is listed but the pilot will in the long run do  what they want to regardless. Remember how this conversation got started, it was  Wayne that asked to change his weight not me, so lets keep that in perspective,  because as the builder I would not solicit the opinion of all the arm chair  quarterbacks that are on this list, rather I would solicit it from  the people I know who have experience in this field and the ramifications  would become readily apparent from that discussion, rather than the pure  conjecture that is taking place.

 Dan

   

 From:  owner-rv10-list-server(at)matronics.com  [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of John  Ackerman

Sent: Friday, May 18, 2007 11:36 AM

To:  rv10-list(at)matronics.com

Subject: Re: Establishing gross  weight

 



   	  Quote: 	
		     

With this being said, it would not be a long stretch stating    that   

an additional 200 pounds in the right location will not cause an    issue   

during normal flight and clear non-turbulent    conditions.    



	


So,  among other things, we need to know...   What is a "long stretch"?  How do we know what a "long stretch" is?



 CG aside, what is a "right location" and what is not? How do we know?

 

  	  Quote: 	
		  ...and clear non-turbulent conditions. I did not    state that it was a smart thing to do and go fly in turbulence, what I  did   state was set it high, flight test it and adjust as    necessary.

    

	
 

   	  Quote: 	
		  Really and truly,    I think the gross weight should be established during the fly-off    period. 	


 

 What are we going to find out from a "flight test", assuming, of course  that the airplane does not flutter, bend detectably, or come apart?

 How do we conduct such a test? How (quantitatively) do you adjust GW based  on test results? How do you know the test has not overstressed the airplane  already, and thus lowered the allowable weight? I suspect that _at least_  education equivalent to that of a B.S. with an emphasis on structures would be  required to take on these issues.

 

 Has anyone tried exiting the 10 while wearing a parachute, even stopped on  the ground?

 

 One could make a pretty good argument for _decreasing_ the gross weight  that we actually fly to. The reason is that -as far as I know- we have no way to  know that our wings are capable of withstanding the same loads as Van's test  article - regardless of whether they are slow build or fast build. Likewise, we  have no way of knowing by how much they might deviate. My personal approach is  to decrease the airspeed rather than the gross weight, though.

 

   	  Quote: 	
		     We are not talking safety    margins, we are talking an aircraft rated in the standard category and as such    will sustain 3.8G's without structural failure. Nuff  said.

	


No, most assuredly _not_ enough  said.



 We have some really wide latitude with experimental amateur-built aircraft,  and rights that are probably the envy of pilots and builders worldwide. With  rights come corresponding responsibilities. I submit that the rights accrue to  us as individuals, but the responsibilities are to our passengers, families,  ourselves, and the families of anyone who might fly or ride in the aircraft down  the line, possibly long after we are gone. Oh, yeah - and to our fellow builders  who would share in the effects of any negative result of our actions.

 

 Thanks to Rick for the excellent insurance discussion, and to James Hovis  for the continuing  rational, understated engineering  perspective.

[quote]



href="http://www.matronics.com/Navigator?RV10-List">http://www.matronics.com/Navigator?RV10-List

href="http://forums.matronics.com">http://forums.matronics.com



[b]

james.k.hovis(at)gmail.co
Guest

Posted: Fri May 18, 2007 8:41 am Post subject: Establishing gross weight

Thanks. Part of my job is to explain engineering rationale to less

educated, but highly skilled production workers. Sometimes I do a

better job of it than at other times. I've never said "that's the way

it is, don't question it!".

Kevin H.

On 5/18/07, John Ackerman <johnag5b(at)cableone.net> wrote:

 	  Quote: 	

 > With this being said, it would not be a long stretch stating that

 > an additional 200 pounds in the right location will not cause an issue

 > during normal flight and clear non-turbulent conditions.

 >

 So, among other things, we need to know...

 What is a "long stretch"?

 How do we know what a "long stretch" is?

 CG aside, what is a "right location" and what is not? How do we know?

 > ...and clear non-turbulent conditions. I did not state that it was

 > a smart thing to do and go fly in turbulence, what I did

 > state was set it high, flight test it and adjust as necessary.

 >

 > Really and truly, I think the gross weight should be established

 > during the fly-off period.

 What are we going to find out from a "flight test", assuming, of

 course that the airplane does not flutter, bend detectably, or come

 apart?

 How do we conduct such a test? How (quantitatively) do you adjust GW

 based on test results? How do you know the test has not overstressed

 the airplane already, and thus lowered the allowable weight? I

 suspect that _at least_ education equivalent to that of a B.S. with

 an emphasis on structures would be required to take on these issues.

 Has anyone tried exiting the 10 while wearing a parachute, even

 stopped on the ground?

 One could make a pretty good argument for _decreasing_ the gross

 weight that we actually fly to. The reason is that -as far as I know-

 we have no way to know that our wings are capable of withstanding the

 same loads as Van's test article - regardless of whether they are

 slow build or fast build. Likewise, we have no way of knowing by how

 much they might deviate. My personal approach is to decrease the

 airspeed rather than the gross weight, though.

 > We are not talking safety margins, we are talking an aircraft rated

 > in the standard category and as such will sustain 3.8G's without

 > structural failure. Nuff said.

 No, most assuredly _not_ enough said.

 We have some really wide latitude with experimental amateur-built

 aircraft, and rights that are probably the envy of pilots and

 builders worldwide. With rights come corresponding responsibilities.

 I submit that the rights accrue to us as individuals, but the

 responsibilities are to our passengers, families, ourselves, and the

 families of anyone who might fly or ride in the aircraft down the

 line, possibly long after we are gone. Oh, yeah - and to our fellow

 builders who would share in the effects of any negative result of our

 actions.

 Thanks to Rick for the excellent insurance discussion, and to James

 Hovis for the continuing  rational, understated engineering perspective.

GRANSCOTT(at)aol.com
Guest

Posted: Fri May 18, 2007 9:59 am Post subject: Establishing gross weight

In a message dated 5/18/2007 12:23:23 PM Eastern Daylight Time, LloydDR(at)wernerco.com writes:

  	  Quote: 	
		  IMHO (my opinion) many people are willing to fly their certified aircraft over gross, and as such they would be willing to fly their experimental over gross, regardless of what the listed gross was. 	


 Dan,

  

 Every pilot makes the final decision on their safety of flight...but having said this, if you over load your plane and you have an incident/accident there is the likelyhood that your insurance company will not honor your insurance policy since you knowingly violated the standards which you created.  But results may vary...or the widow and children left on the ground.

  

 Patrick



See what's free at AOL.com. 

  [quote][b]

rleffler

Joined: 05 Nov 2006
Posts: 680

Posted: Fri May 18, 2007 12:09 pm Post subject: Establishing gross weight

I've swapped some email with Susan Sedlacheck at EAA.  We may be able to get

one of the forum buildings, but they are only available in the evening.  She

also talked about the porch at the Homebuilder's HQ, but I think we could

easily overwhelm that area.



Just some more options if interested.......



Bob

--

_________________
Bob Leffler
N410BL - Phase I
http://mykitlog.com/rleffler

apilot2(at)gmail.com
Guest

Posted: Fri May 18, 2007 4:37 pm Post subject: Establishing gross weight

The C172 increases came with gear changes and later engine change. It

went from 2200 to 2300, and eventually I think 2400...not a major

increase. Also, the airframe was designed as a taildragger, so gear

and gearbox had to be designed stronger.  Those weren't paper changes

but fully tested, and there were structural changes. Different gear

legs, different struts, etc.



On 5/18/07, Lloyd, Daniel R. <LloydDR(at)wernerco.com> wrote:

 	  Quote: 	
		   The venerable Cessna 172 has had its max weight increased several times

 during its life, equaling several hundred pounds and without structural

 modification. This was accomplished by continued testing and analyzing the

 results.

LloydDR(at)wernerco.com
Guest

Posted: Fri May 18, 2007 8:11 pm Post subject: Establishing gross weight

Not true for all of the weight changes in the history of the 172, but

like you said 200 lbs is not a major increase?



--

james.k.hovis(at)gmail.co
Guest

Posted: Sat May 19, 2007 3:42 am Post subject: Establishing gross weight

I'd like to get back to OSH (haven't been since '96) and at least meet

y'all at the camp. Unfortunantly, my vacation time will be ate up by

other hobby and family time. Maybe next year....



Kevin H.



On 5/18/07, Bob Leffler <rvmail(at)thelefflers.com> wrote:

[quote] 



 I've swapped some email with Susan Sedlacheck at EAA.  We may be able to get

 one of the forum buildings, but they are only available in the evening.  She

 also talked about the porch at the Homebuilder's HQ, but I think we could

 easily overwhelm that area.



 Just some more options if interested.......



 Bob

 --

LloydDR(at)wernerco.com
Guest

Posted: Sat May 19, 2007 4:07 am Post subject: Establishing gross weight

Just come in for the first weekend or the second. Depending on how far

it is, I might be willing to come get you in my overweight 10!!!

Remember all of this is in jest and we are just educating each other!

Dan

N289DT RV10E (She is on her own gear and rolling with a mounted Subbie)



PS Michael, I did try to post the photos last night at midnight but

Matronics kicked'em back because they were too big. I will resize and

send again



--

apilot2(at)gmail.com
Guest

Posted: Sat May 19, 2007 4:29 am Post subject: Establishing gross weight

Not considering it took more than fifteen years to get there, totally

different landing gear, different engine, different fuselage. Remember

it started as the C170 in 1948, so there are a lot more changes than

you realize. Almost nothing from 1969 on is original.



On 5/18/07, Lloyd, Daniel R. <LloydDR(at)wernerco.com> wrote:

[quote] 



 Not true for all of the weight changes in the history of the 172, but

 like you said 200 lbs is not a major increase?



 --

james.k.hovis(at)gmail.co
Guest

Posted: Sat May 19, 2007 4:50 am Post subject: Establishing gross weight

I'd love a ride if you don't mind an overweight passenger too. 



Actually, doing an equivalent strength analysis isn't that difficult

for someone familiar with the process. There are several things about

the structure affected that needs to be known (sizes, material types,

fasteners, etc.) to see exactly how much a gross weight increase will

affect the structure. I'm just very skeptical of anyone just pencil

whipping a higher gross weight on any airplane without checking with a

professional. While the RV-10 may be able to tolerate a 10% weight

increase without structural modification (only as an example, I want

to do or see an analysis before fully agreeing to that statement),

other airplanes can't. See this from Avweb about what severe

turbulence can do to you for someone who wasn't careful in their

flight planning:

http://www.avweb.com/news/probablecause/probable_cause_32_incomplete_briefing_195146-1.html



I'm going to keep watch on the Subbie installation to see how it pans

out. Good alternatinves are always welcome to me.



Kevin H.

(putting in some Sat. OT)

On 5/19/07, Lloyd, Daniel R. <LloydDR(at)wernerco.com> wrote:

[quote] 



 Just come in for the first weekend or the second. Depending on how far

 it is, I might be willing to come get you in my overweight 10!!!

 Remember all of this is in jest and we are just educating each other!

 Dan

 N289DT RV10E (She is on her own gear and rolling with a mounted Subbie)



 PS Michael, I did try to post the photos last night at midnight but

 Matronics kicked'em back because they were too big. I will resize and

 send again



 --

james.k.hovis(at)gmail.co
Guest

Posted: Sat May 19, 2007 5:02 am Post subject: Establishing gross weight

Kelly,

  One thing to remember is in the "old" days, engineering analysis

tended to be extremely conservative which resulted in structures that

were actually more robust than needed. As better analysis tools came

on line (for example NASTRAN), it was easier for Cessna and others to

re-look at old designs and show "upgrades" (i.e. weight and HP

increases) without altering the basic airframes too much. Aircraft

design still tends to be conservative. Why do you think radical design

departures take SO long to get FAA approval if a TC is sought (see

Beech Starship for composite construction)? Fortunantly for Cirrus,

Diamond, and Columbia, Beech spent the money. But the point is, weight

increases on TC aircraft aren't just pencil-whipped, there are

rational professional analyses behind them.

Kevin H.

On 5/19/07, Kelly McMullen <apilot2(at)gmail.com> wrote:

[quote] 

 Not considering it took more than fifteen years to get there, totally

 different landing gear, different engine, different fuselage. Remember

 it started as the C170 in 1948, so there are a lot more changes than

 you realize. Almost nothing from 1969 on is original.

 On 5/18/07, Lloyd, Daniel R. <LloydDR(at)wernerco.com> wrote:

 > 

 >

 > Not true for all of the weight changes in the history of the 172, but

 > like you said 200 lbs is not a major increase?

 >

 > --

LloydDR(at)wernerco.com
Guest

Posted: Sat May 19, 2007 6:51 pm Post subject: Establishing gross weight

What I am talking about is the changes in the gross weight without

changing/ modifying the airframe. Research the history of the aircraft

and you will see many gross weight changes without any modification to

the airframe, rather extensive testing was accomplished and the gross

weight was modified. This is what I am referring to in this situation,

if the builder is going to change the gross weight than a test period is

required to verify it is safe, and as the builder they are the ones that

need to determine how much and what testing is necessary to be okay with

the change.

Dan



--

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