Author: "maxwelltl54" <heirloomi@...> Time: Mon Oct 4, 2004 6:06 pm PDT Link
This is probably a dumb question but still the thought seems
reasonable to my pea brain. Please educate me on what I am
overlooking or where I am all wet.
Van engineers the aircraft for 6g aerobatic use. So therefore a
200lb pilot pulling 6g's exerts buttock forces of 1200lbs on the seat
cushion. Likewise a 100lb baggage load exerts a force of 600lbs on
the baggage compartment floor.
Maybe you can see where I am going with this.
If a pilot is planning a leisurely cross-country flight without
aerobatics involved, and if a pilot doesn't take any actions and if
the plane doesn't enounter any turbulence such that the maximum G
force exerted on the aircraft is 3g's or less, then concieveably the
pilot could weight 400lbs and the baggage could weigh 200 lbs and the
airframe would be subjected to no more force than in the previous
example.
So in low G situations, the RVs could be capable of carrying a much
larger payload than advertised.
Obviously, take-off, climb, and landing performance would suffer as
well but with a long enough runway I would think things should work
just fine.
No/Yes?
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Author: "Kyle Boatright" <kboatright1@...> Time: Mon Oct 4, 2004 6:50 pm PDT Link
To some extent, yes, these airplanes will fly at well above the published gross weights.. The most notable example is Jon Johanssen on his long distance flights. The downside is that the stall speed will increase and you're eating into the structural margin for your landing gear and tires. Also, your tire and brake wear will change signficantly. Finally, the flying qualities really suffer. There is a huge difference when I fly my RV-6 at 1675 lbs versus 100 lbs lighter. Especially in the pattern, the airplane has a much better feel at lower weights.
KB
----- Original Message -----
From: maxwelltl54
To: RV7and7A@yahoogroups.com
Sent: Monday, October 04, 2004 9:05 PM
Subject: [RV7Yahoo] Dumb Weight Question
This is probably a dumb question but still the thought seems
reasonable to my pea brain. Please educate me on what I am
overlooking or where I am all wet.
Van engineers the aircraft for 6g aerobatic use. So therefore a
200lb pilot pulling 6g's exerts buttock forces of 1200lbs on the seat
cushion. Likewise a 100lb baggage load exerts a force of 600lbs on
the baggage compartment floor.
Maybe you can see where I am going with this.
If a pilot is planning a leisurely cross-country flight without
aerobatics involved, and if a pilot doesn't take any actions and if
the plane doesn't enounter any turbulence such that the maximum G
force exerted on the aircraft is 3g's or less, then concieveably the
pilot could weight 400lbs and the baggage could weigh 200 lbs and the
airframe would be subjected to no more force than in the previous
example.
So in low G situations, the RVs could be capable of carrying a much
larger payload than advertised.
Obviously, take-off, climb, and landing performance would suffer as
well but with a long enough runway I would think things should work
just fine.
No/Yes?
Van's Air Force - World Wide Wing
www.vansaircraft.net
Yahoo! Groups Sponsor
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Author: Phil Birkelbach <phil@...> Time: Tue Oct 5, 2004 7:29 am PDT Link
First the calculated loads are not based on what the seat can handle
(although that must be considered) but rather what the wing spar can
handle. I agree that your 400lb pilot at 2g's is less load on the spar
than the 200lb pilot at 6g's but that is not all there is to the
equation. Above all you have to watch your CG. According to your
formula you could put 300 or 200 lbs of baggage in the plane and then
your 300lb self and your really large girlfriend (just kidding :-) and
throw the CG so far off that your airplane will be uncontrollable. But
as long as you stay inside around 2g's the wings will stay attached.
You'll be a smear in a field on the departure end of the airport but
your wing spars will have survived the flight (maybe not the landing).
You also must consider things like the stall speed and the effects that
weight has on handling, brakes, landing gear, takeoff and landing
distance, etc. Real airplanes (Taildraggers) will get more and more
difficult to handle on the ground the further aft the CG moves.
Remember that all passenger weight and baggage causes the CG to aft (at
least for the RV-6,7,9) and burning fuel also makes it go aft.
There is much more to consider on weight in an airplane than simply what
the structure can handle.
Godspeed,
Phil Birkelbach - Houston Texas
RV-7 N727WB (Reserved) - Panel
http://www.myrv7.com
maxwelltl54 wrote:
>This is probably a dumb question but still the thought seems
>reasonable to my pea brain. Please educate me on what I am
>overlooking or where I am all wet.
>
>Van engineers the aircraft for 6g aerobatic use. So therefore a
>200lb pilot pulling 6g's exerts buttock forces of 1200lbs on the seat
>cushion. Likewise a 100lb baggage load exerts a force of 600lbs on
>the baggage compartment floor.
>
>Maybe you can see where I am going with this.
>
>If a pilot is planning a leisurely cross-country flight without
>aerobatics involved, and if a pilot doesn't take any actions and if
>the plane doesn't enounter any turbulence such that the maximum G
>force exerted on the aircraft is 3g's or less, then concieveably the
>pilot could weight 400lbs and the baggage could weigh 200 lbs and the
>airframe would be subjected to no more force than in the previous
>example.
>
>So in low G situations, the RVs could be capable of carrying a much
>larger payload than advertised.
>
>Obviously, take-off, climb, and landing performance would suffer as
>well but with a long enough runway I would think things should work
>just fine.
>
>No/Yes?
>Van's Air Force - World Wide Wing
>www.vansaircraft.net
>Yahoo! Groups Links
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Author: "Rich" <easylivin_ak@...> Time: Tue Oct 5, 2004 7:29 am PDT Link
You are right, it is a dumb question to ask in a pilot forum like
this. Are you a certified pilot? Structural design limits have
nothing to do with A/C performance limits and CG limits for
controllability. Do you not understand that the airplane could be
loaded below allowable gross weight and still be unflyable because
of an aft CG due to improper loading in the baggage compartment?
Also, you talk about aerobatic G limits which have further
restrictions on CG location and gross weight, then talk about
filling the baggage compartment?
--- In RV7and7A@yahoogroups.com, "maxwelltl54" <heirloomi@a...>
wrote:
> This is probably a dumb question but still the thought seems
> reasonable to my pea brain. Please educate me on what I am
> overlooking or where I am all wet.
>
> Van engineers the aircraft for 6g aerobatic use. So therefore a
> 200lb pilot pulling 6g's exerts buttock forces of 1200lbs on the
seat
> cushion. Likewise a 100lb baggage load exerts a force of 600lbs
on
> the baggage compartment floor.
>
> Maybe you can see where I am going with this.
>
> If a pilot is planning a leisurely cross-country flight without
> aerobatics involved, and if a pilot doesn't take any actions and
if
> the plane doesn't enounter any turbulence such that the maximum G
> force exerted on the aircraft is 3g's or less, then concieveably
the
> pilot could weight 400lbs and the baggage could weigh 200 lbs and
the
> airframe would be subjected to no more force than in the previous
> example.
>
> So in low G situations, the RVs could be capable of carrying a
much
> larger payload than advertised.
>
> Obviously, take-off, climb, and landing performance would suffer
as
> well but with a long enough runway I would think things should
work
> just fine.
>
> No/Yes?
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Author: James King <kinger@...> Time: Tue Oct 5, 2004 8:51 am PDT Link
It does not matter where one is in life with knowledge. We should
always show professionalism and respect. The only dumb question is the
question not asked. Provide information and restrain from attacking
people. Everyone's knowledge is different, which is why we are all here
to help and gain knowledge.
jim
Rich wrote:
> You are right, it is a dumb question to ask in a pilot forum like
> this. Are you a certified pilot? Structural design limits have
> nothing to do with A/C performance limits and CG limits for
> controllability. Do you not understand that the airplane could be
> loaded below allowable gross weight and still be unflyable because
> of an aft CG due to improper loading in the baggage compartment?
> Also, you talk about aerobatic G limits which have further
> restrictions on CG location and gross weight, then talk about
> filling the baggage compartment?
> --- In RV7and7A@yahoogroups.com, "maxwelltl54" <heirloomi@a...>
> wrote:
> > This is probably a dumb question but still the thought seems
> > reasonable to my pea brain. Please educate me on what I am
> > overlooking or where I am all wet.
> >
> > Van engineers the aircraft for 6g aerobatic use. So therefore a
> > 200lb pilot pulling 6g's exerts buttock forces of 1200lbs on the
> seat
> > cushion. Likewise a 100lb baggage load exerts a force of 600lbs
> on
> > the baggage compartment floor.
> >
> > Maybe you can see where I am going with this.
> >
> > If a pilot is planning a leisurely cross-country flight without
> > aerobatics involved, and if a pilot doesn't take any actions and
> if
> > the plane doesn't enounter any turbulence such that the maximum G
> > force exerted on the aircraft is 3g's or less, then concieveably
> the
> > pilot could weight 400lbs and the baggage could weigh 200 lbs and
> the
> > airframe would be subjected to no more force than in the previous
> > example.
> >
> > So in low G situations, the RVs could be capable of carrying a
> much
> > larger payload than advertised.
> >
> > Obviously, take-off, climb, and landing performance would suffer
> as
> > well but with a long enough runway I would think things should
> work
> > just fine.
> >
> > No/Yes?
> Van's Air Force - World Wide Wing
> www.vansaircraft.net
> Yahoo! Groups Sponsor
> ADVERTISEMENT
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Author: "Bob" <nutjob911@...> Time: Tue Oct 5, 2004 8:55 am PDT Link
--I have flown a RV-7 with 0-320,450lbs of pilots and next to no
gas. Pitch sensitivity is the real issue, made me rethink how I am
going to build this plane ,I now wish I had not primed my tail at
all. So it "rusts out", I go buy a new one on ebay for $500 and very
glad I cut the lighting holes. Manual trim ,c/s metal prop or at
least f/p metal.nothing mounted past the back side of the spar.
Point is keep as much weight as far foward as possible.Someone else
said it the best "Pump the weight in,Pump the fun out".RV's are
magnificent birds to fly but just like wild animals mistreat them
and they will bite you. Anyone thinking they can teach themselves
to fly this plane without a check out will no doubt wish they
rethought that decision.
- In RV7and7A@yahoogroups.com, "Rich" <easylivin_ak@y...> wrote:
> You are right, it is a dumb question to ask in a pilot forum like
> this. Are you a certified pilot? Structural design limits have
> nothing to do with A/C performance limits and CG limits for
> controllability. Do you not understand that the airplane could be
> loaded below allowable gross weight and still be unflyable because
> of an aft CG due to improper loading in the baggage compartment?
> Also, you talk about aerobatic G limits which have further
> restrictions on CG location and gross weight, then talk about
> filling the baggage compartment?
> --- In RV7and7A@yahoogroups.com, "maxwelltl54" <heirloomi@a...>
> wrote:
> > This is probably a dumb question but still the thought seems
> > reasonable to my pea brain. Please educate me on what I am
> > overlooking or where I am all wet.
> >
> > Van engineers the aircraft for 6g aerobatic use. So therefore a
> > 200lb pilot pulling 6g's exerts buttock forces of 1200lbs on the
> seat
> > cushion. Likewise a 100lb baggage load exerts a force of 600lbs
> on
> > the baggage compartment floor.
> >
> > Maybe you can see where I am going with this.
> >
> > If a pilot is planning a leisurely cross-country flight without
> > aerobatics involved, and if a pilot doesn't take any actions and
> if
> > the plane doesn't enounter any turbulence such that the maximum
G
> > force exerted on the aircraft is 3g's or less, then concieveably
> the
> > pilot could weight 400lbs and the baggage could weigh 200 lbs
and
> the
> > airframe would be subjected to no more force than in the
previous
> > example.
> >
> > So in low G situations, the RVs could be capable of carrying a
> much
> > larger payload than advertised.
> >
> > Obviously, take-off, climb, and landing performance would suffer
> as
> > well but with a long enough runway I would think things should
> work
> > just fine.
> >
> > No/Yes?
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Author: "Gary Seaton" <seatonconsulting@...> Time: Tue Oct 5, 2004 9:36 am PDT Link
Amen, Jim!
Gary Seaton
Corrales, NM
>From: James King <kinger@mac.com>
>Reply-To: RV7and7A@yahoogroups.com
>To: RV7and7A@yahoogroups.com
>Subject: Re: [RV7Yahoo] Re: Dumb Weight Question
>Date: Tue, 05 Oct 2004 11:02:29 -0400
>It does not matter where one is in life with knowledge. We should
>always show professionalism and respect. The only dumb question is the
>question not asked. Provide information and restrain from attacking
>people. Everyone's knowledge is different, which is why we are all here
>to help and gain knowledge.
>
>jim
>
>Rich wrote:
> > You are right, it is a dumb question to ask in a pilot forum like
> > this. Are you a certified pilot? Structural design limits have
> > nothing to do with A/C performance limits and CG limits for
> > controllability. Do you not understand that the airplane could be
> > loaded below allowable gross weight and still be unflyable because
> > of an aft CG due to improper loading in the baggage compartment?
> > Also, you talk about aerobatic G limits which have further
> > restrictions on CG location and gross weight, then talk about
> > filling the baggage compartment?
> > --- In RV7and7A@yahoogroups.com, "maxwelltl54" <heirloomi@a...>
> > wrote:
> > > This is probably a dumb question but still the thought seems
> > > reasonable to my pea brain. Please educate me on what I am
> > > overlooking or where I am all wet.
> > >
> > > Van engineers the aircraft for 6g aerobatic use. So therefore a
> > > 200lb pilot pulling 6g's exerts buttock forces of 1200lbs on the
> > seat
> > > cushion. Likewise a 100lb baggage load exerts a force of 600lbs
> > on
> > > the baggage compartment floor.
> > >
> > > Maybe you can see where I am going with this.
> > >
> > > If a pilot is planning a leisurely cross-country flight without
> > > aerobatics involved, and if a pilot doesn't take any actions and
> > if
> > > the plane doesn't enounter any turbulence such that the maximum G
> > > force exerted on the aircraft is 3g's or less, then concieveably
> > the
> > > pilot could weight 400lbs and the baggage could weigh 200 lbs and
> > the
> > > airframe would be subjected to no more force than in the previous
> > > example.
> > >
> > > So in low G situations, the RVs could be capable of carrying a
> > much
> > > larger payload than advertised.
> > >
> > > Obviously, take-off, climb, and landing performance would suffer
> > as
> > > well but with a long enough runway I would think things should
> > work
> > > just fine.
> > >
> > > No/Yes?
> > Van's Air Force - World Wide Wing
> > www.vansaircraft.net
> > Yahoo! Groups Sponsor
> > ADVERTISEMENT
> > click here
> >
><http://us.ard.yahoo.com/SIG=129av9c66/M=295196.4901138.6071305.3001176/D=groups/S=1705340085:HM/EXP=1097072975/A=2128215/R=0/SIG=10se96mf6/*http://companion.yahoo.com
> > ------------------------------------------------------------------------
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> >
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Author: "Jon Baker" <jon@...> Time: Fri Oct 8, 2004 9:02 am PDT Link
Now that blunt responders have been properly chastised, I'd like to
respond to the original question.
Yes, you can easily calculate a higher gross weight based on the
aerobatic gross weight. Just multiply the aerobatic weight limit by
6 and then divide by the the g-rating of whatever category you're
calculating (Normal, Utility) to arrive at the gross weight for that
category. You will find that the gross weight set by Vans is much
lower than the airframe's capability in the Normal category. The
limiting factor is not the spar or the seat or anything to do with
CG. It's the landing gear.
When I was building my 6A (which has a Vans-suggested gross of 1650),
the 7 came out, with its 1800 lb gross. Having done the calculations
and realized that the gear was the limiting factor, I called Vans to
see if I could buy the 7 gear for my 6. The Van's response was very
interesting.
They told me that I was right about the gear being the limiting
factor, but that the 7 had exactly the same gear. They said the
reason they raised the gross weight was the field experience of so
many Rv6 pilots setting their gross at 1800 or above with no problems!
Consequently, I set my gross at 1950 (still well under normal
limits), with the caveat in my POH that landing weight had to be
under 1800 lbs. Airplanes always gain weight as they age, so I gave
myself a fudge-factor.
Regarding CG issues, a C/S prop basically solves that problem. With
100 lbs of baggage, I can can carry over 400 lbs of people without
exceeding the aft limit, even with minimun fuel.
By the way, I would consider the 100 lb baggage limit to be
structural. The fact that the spar can handle 6 G's doesn't mean the
baggage floor can. You don't do aerobatics with two-weeks worth of
luggage in the back!
Jon.
--- In RV7and7A@yahoogroups.com, "maxwelltl54" <heirloomi@a...> wrote:
> This is probably a dumb question but still the thought seems
> reasonable to my pea brain. Please educate me on what I am
> overlooking or where I am all wet.
>
> Van engineers the aircraft for 6g aerobatic use. So therefore a
> 200lb pilot pulling 6g's exerts buttock forces of 1200lbs on the
seat
> cushion. Likewise a 100lb baggage load exerts a force of 600lbs on
> the baggage compartment floor.
>
> Maybe you can see where I am going with this.
>
> If a pilot is planning a leisurely cross-country flight without
> aerobatics involved, and if a pilot doesn't take any actions and if
> the plane doesn't enounter any turbulence such that the maximum G
> force exerted on the aircraft is 3g's or less, then concieveably
the
> pilot could weight 400lbs and the baggage could weigh 200 lbs and
the
> airframe would be subjected to no more force than in the previous
> example.
>
> So in low G situations, the RVs could be capable of carrying a much
> larger payload than advertised.
>
> Obviously, take-off, climb, and landing performance would suffer as
> well but with a long enough runway I would think things should work
> just fine.
>
> No/Yes?
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Author: "Rich" <easylivin_ak@...> Time: Fri Oct 8, 2004 10:31 am PDT Link
Hi Jon,
Interesting post and you seem to have a grasp of the basics of A/C
loading. I would add a few words of caution to other pilots that may
want to increase their GW as you have done.
It is not quite as simple as just doing what you have said, there
are others factors to consider too:
With your plane loaded to your new limits and at worst case Aft CG
what will be the effects on aerodynamics such as spin recovery,
static and dynamic stability in all possible flight operations,
control surface limitations,etc. The higher your weight in flight,
the more susceptable your A/C is to catastrophic damage from severe
turbulance and have you tested it in those conditions? What is your
new manuevering airspeed? These are just the tip of the iceberg.
When Van's upped the GW to 1800 they did so based on thousands of
hours of operations with hundreds of airplanes and with the blessing
of their aeronautical engineer. Anyone upping it further is now
a "serious" test pilot and better have the qualifications for it.
When you go to sell that airplane someday you had better change the
GW back to 1800 in the POH unless you want to set yourself up for a
lawsuit from a widowed wife seeking to empty your pockets.
Adding a CS prop may not solve all CG problems at all. Some
aircraft may now limit out on GW before you are able to get that
100lbs. of baggage in there. Each builder will need to evaluate that
on his own depending on how much other equipment he is planning on
adding as well and where that equipment is going.
Baggage limits themselves are not just limited by the floor strength
and spar strength and aft CG limits but other factors such as spin
recovery and all the other factors I mentioned.
I am not setting myself up as the "Expert" on this, I would like to
hear from other pilots and maybe we have an actual aeronautical
engineer out there who can comment.
Anyway, thank you for your posting.
Rich
RV7and7A@yahoogroups.com, "Jon Baker" <jon@s...> wrote:
> Now that blunt responders have been properly chastised, I'd like
to
> respond to the original question.
>
> Yes, you can easily calculate a higher gross weight based on the
> aerobatic gross weight. Just multiply the aerobatic weight limit
by
> 6 and then divide by the the g-rating of whatever category you're
> calculating (Normal, Utility) to arrive at the gross weight for
that
> category. You will find that the gross weight set by Vans is much
> lower than the airframe's capability in the Normal category. The
> limiting factor is not the spar or the seat or anything to do with
> CG. It's the landing gear.
>
> When I was building my 6A (which has a Vans-suggested gross of
1650),
> the 7 came out, with its 1800 lb gross. Having done the
calculations
> and realized that the gear was the limiting factor, I called Vans
to
> see if I could buy the 7 gear for my 6. The Van's response was
very
> interesting.
>
> They told me that I was right about the gear being the limiting
> factor, but that the 7 had exactly the same gear. They said the
> reason they raised the gross weight was the field experience of so
> many Rv6 pilots setting their gross at 1800 or above with no
problems!
>
> Consequently, I set my gross at 1950 (still well under normal
> limits), with the caveat in my POH that landing weight had to be
> under 1800 lbs. Airplanes always gain weight as they age, so I
gave
> myself a fudge-factor.
>
> Regarding CG issues, a C/S prop basically solves that problem.
With
> 100 lbs of baggage, I can can carry over 400 lbs of people without
> exceeding the aft limit, even with minimun fuel.
>
> By the way, I would consider the 100 lb baggage limit to be
> structural. The fact that the spar can handle 6 G's doesn't mean
the
> baggage floor can. You don't do aerobatics with two-weeks worth
of
> luggage in the back!
>
> Jon.
> --- In RV7and7A@yahoogroups.com, "maxwelltl54" <heirloomi@a...>
wrote:
> > This is probably a dumb question but still the thought seems
> > reasonable to my pea brain. Please educate me on what I am
> > overlooking or where I am all wet.
> >
> > Van engineers the aircraft for 6g aerobatic use. So therefore a
> > 200lb pilot pulling 6g's exerts buttock forces of 1200lbs on the
> seat
> > cushion. Likewise a 100lb baggage load exerts a force of 600lbs
on
> > the baggage compartment floor.
> >
> > Maybe you can see where I am going with this.
> >
> > If a pilot is planning a leisurely cross-country flight without
> > aerobatics involved, and if a pilot doesn't take any actions and
if
> > the plane doesn't enounter any turbulence such that the maximum
G
> > force exerted on the aircraft is 3g's or less, then concieveably
> the
> > pilot could weight 400lbs and the baggage could weigh 200 lbs
and
> the
> > airframe would be subjected to no more force than in the
previous
> > example.
> >
> > So in low G situations, the RVs could be capable of carrying a
much
> > larger payload than advertised.
> >
> > Obviously, take-off, climb, and landing performance would suffer
as
> > well but with a long enough runway I would think things should
work
> > just fine.
> >
> > No/Yes?
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Author: bikcrzy@... Time: Fri Oct 8, 2004 11:19 am PDT Link
Rich,
If the DAR or FAA buys the plane at a 1950 Gross, how would that be gross negligence for a lawsuit? John Robinson RV-7A Electrical system.
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Author: "Rich" <easylivin_ak@...> Time: Fri Oct 8, 2004 1:59 pm PDT Link
Good point,
If I were the FAA, I would not certify it at 1950 unless the
builder/pilot had done extensive flight testing and had
documentation to prove it. I wonder if all that was done here?
After all, the pilot can go up the next day after he gets his
airworthiness certificate with a passenger and do everything in his
Op Spec. If he ends up killing that passenger for what ever reason,
do you think there is not a high priced attorney out there who will
file a lawsuit on behalf of the widow? And what if he convinces a
jury that you were negligent, after all, you will not be there to
defend yourself. It will just be the attornies on both sides and the
weeping widow in front of that jury. Oops, there goes your entire
estate !
Of course all this could happen even if you are certified at 1800
too. Just makes you think twice before carrying a passenger not in
your family, especially if you are a pilot that is rusty on your A/C
loading knowledge. (and have documented your lack of knowledge on
sites like this) What would an attorney do with a copy of "dumb
question" if Maxwell ever crashes?
Rich
-- In RV7and7A@yahoogroups.com, bikcrzy@a... wrote:
>
> Rich,
>
> If the DAR or FAA buys the plane at a 1950 Gross, how would
that be gross negligence for a lawsuit? John Robinson RV-7A
Electrical system.
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Author: customtrans@... Time: Fri Oct 8, 2004 2:52 pm PDT Link
Not to be a smart bun here, but why don't we just take the emmediate family
members up only. Then we can be safe on the one.
sa
-----Original Message-----
From: Rich [mailto:easylivin_ak@yahoo.com]
Sent: Friday, October 08, 2004 1:51 PM
To: RV7and7A@yahoogroups.com
Subject: [RV7Yahoo] Re: Dumb Weight Question
Good point,
If I were the FAA, I would not certify it at 1950 unless the
builder/pilot had done extensive flight testing and had
documentation to prove it. I wonder if all that was done here?
After all, the pilot can go up the next day after he gets his
airworthiness certificate with a passenger and do everything in his
Op Spec. If he ends up killing that passenger for what ever reason,
do you think there is not a high priced attorney out there who will
file a lawsuit on behalf of the widow? And what if he convinces a
jury that you were negligent, after all, you will not be there to
defend yourself. It will just be the attornies on both sides and the
weeping widow in front of that jury. Oops, there goes your entire
estate !
Of course all this could happen even if you are certified at 1800
too. Just makes you think twice before carrying a passenger not in
your family, especially if you are a pilot that is rusty on your A/C
loading knowledge. (and have documented your lack of knowledge on
sites like this) What would an attorney do with a copy of "dumb
question" if Maxwell ever crashes?
Rich
-- In RV7and7A@yahoogroups.com, bikcrzy@a... wrote:
>
> Rich,
>
> If the DAR or FAA buys the plane at a 1950 Gross, how would
that be gross negligence for a lawsuit? John Robinson RV-7A
Electrical system.
Van's Air Force - World Wide Wing
www.vansaircraft.net
Yahoo! Groups Sponsor
ADVERTISEMENT
----------------------------------------------------------------------------
--
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Author: "Kyle Boatright" <kboatright1@...> Time: Fri Oct 8, 2004 4:24 pm PDT Link
This is my first response (of several) to a couple of different weight related threads.
My thoughts are embedded in the earlier post...
KB
----- Original Message -----
From: Rich
To: RV7and7A@yahoogroups.com
Sent: Friday, October 08, 2004 4:51 PM
Subject: [RV7Yahoo] Re: Dumb Weight Question
Good point,
If I were the FAA, I would not certify it at 1950 unless the
builder/pilot had done extensive flight testing and had
documentation to prove it. I wonder if all that was done here?
NO. You set your plane's gross weight before the first flight. You test fly it to see if that weight (and the CG) you're using gives the performance and flight characterisitics you choose. If necessary, you can re-set the gross weight or CG limits during/after testing.
After all, the pilot can go up the next day after he gets his
airworthiness certificate with a passenger and do everything in his
Op Spec. If he ends up killing that passenger for what ever reason,
do you think there is not a high priced attorney out there who will
file a lawsuit on behalf of the widow? And what if he convinces a
jury that you were negligent, after all, you will not be there to
defend yourself. It will just be the attornies on both sides and the
weeping widow in front of that jury. Oops, there goes your entire
estate !
Crash an airplane, you're probably going to get sued. 90% of the time, it is pilot error, and you'll get sued the rest of the time anyway. As pilot, you are responsible for the airworthy condition of the craft, so if it breaks, that's on you too. Fatalistic, but if liability is the big concern, flying isn't the best of hobbies.
Of course all this could happen even if you are certified at 1800
too. Just makes you think twice before carrying a passenger not in
your family, especially if you are a pilot that is rusty on your A/C
loading knowledge. (and have documented your lack of knowledge on
sites like this) What would an attorney do with a copy of "dumb
question" if Maxwell ever crashes?
Rich
-- In RV7and7A@yahoogroups.com, bikcrzy@a... wrote:
>
> Rich,
>
> If the DAR or FAA buys the plane at a 1950 Gross, how would
that be gross negligence for a lawsuit? John Robinson RV-7A
Electrical system.
Van's Air Force - World Wide Wing
www.vansaircraft.net
Yahoo! Groups Sponsor
ADVERTISEMENT
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[Non-text portions of this message have been removed]
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Author: "Kyle Boatright" <kboatright1@...> Time: Fri Oct 8, 2004 5:06 pm PDT Link
Again, one of a couple of responses to related posts. I think it is important that people understand that aircraft structures are not simple and that you can make bad assumptions that put you at more risk than you realize. Aeronautical Engineering (I'm not one, but I did stay at a Holiday Inn Express) isn't something to be taken lightly... My answers are embedded in the post below...
Kyle Boatright
----- Original Message -----
From: Jon Baker
To: RV7and7A@yahoogroups.com
Sent: Friday, October 08, 2004 9:11 AM
Subject: [RV7Yahoo] Re: Dumb Weight Question
Now that blunt responders have been properly chastised, I'd like to
respond to the original question.
Yes, you can easily calculate a higher gross weight based on the
aerobatic gross weight.
This is one of those cases where people use math to convince themselves that they are safe in their decision to accept a higher gross weight. However, the math isn't as simple as many people think, so when they run the numbers, they get a wrong answer, which is dangerous.
The original gross weight was determined with a certain weight distribution. That distribution assumed something along the lines of "no more than X pounds in the fuselage". Get away from that weight distribution by piling stuff in the fuselage (big engine, B-747 panel, Constant Speed Prop, a couple of 250 lb people, and a couple of steamer trunks in the back) and the wing bending moments get worse, and not in a linear fashion. (If you're over gross, the extra weight is probably in the fuselage - you are not likely to get 75 gallons in your 42 gallon wing tanks).
Imagine an eight foot 2"x4" board spanning two sawhorses. If you evenly distribute 100 pounds along the length of the 2x4, it'll probably hold. However, if you put all 100 pounds in the dead center, the 2x4 will fail. Same thing with your main spar. Put too much weight in the center of the beam (i.e. the fuselage), and your safety margin is reduced.
Just multiply the aerobatic weight limit by
6 and then divide by the the g-rating of whatever category you're
calculating (Normal, Utility) to arrive at the gross weight for that
category. You will find that the gross weight set by Vans is much
lower than the airframe's capability in the Normal category. The
limiting factor is not the spar or the seat or anything to do with
CG. It's the landing gear.
When I was building my 6A (which has a Vans-suggested gross of 1650),
the 7 came out, with its 1800 lb gross. Having done the calculations
and realized that the gear was the limiting factor, I called Vans to
see if I could buy the 7 gear for my 6. The Van's response was very
interesting.
They told me that I was right about the gear being the limiting
factor, but that the 7 had exactly the same gear. They said the
reason they raised the gross weight was the field experience of so
many Rv6 pilots setting their gross at 1800 or above with no problems!
Consequently, I set my gross at 1950 (still well under normal
limits), with the caveat in my POH that landing weight had to be
under 1800 lbs. Airplanes always gain weight as they age, so I gave
myself a fudge-factor.
Regarding CG issues, a C/S prop basically solves that problem. With
100 lbs of baggage, I can can carry over 400 lbs of people without
exceeding the aft limit, even with minimun fuel.
By the way, I would consider the 100 lb baggage limit to be
structural. The fact that the spar can handle 6 G's doesn't mean the
baggage floor can. You don't do aerobatics with two-weeks worth of
luggage in the back!
Jon.
--- In RV7and7A@yahoogroups.com, "maxwelltl54" <heirloomi@a...> wrote:
> This is probably a dumb question but still the thought seems
> reasonable to my pea brain. Please educate me on what I am
> overlooking or where I am all wet.
>
> Van engineers the aircraft for 6g aerobatic use. So therefore a
> 200lb pilot pulling 6g's exerts buttock forces of 1200lbs on the
seat
> cushion. Likewise a 100lb baggage load exerts a force of 600lbs on
> the baggage compartment floor.
>
> Maybe you can see where I am going with this.
>
> If a pilot is planning a leisurely cross-country flight without
> aerobatics involved, and if a pilot doesn't take any actions and if
> the plane doesn't enounter any turbulence such that the maximum G
> force exerted on the aircraft is 3g's or less, then concieveably
the
> pilot could weight 400lbs and the baggage could weigh 200 lbs and
the
> airframe would be subjected to no more force than in the previous
> example.
>
> So in low G situations, the RVs could be capable of carrying a much
> larger payload than advertised.
>
> Obviously, take-off, climb, and landing performance would suffer as
> well but with a long enough runway I would think things should work
> just fine.
>
> No/Yes?
Van's Air Force - World Wide Wing
www.vansaircraft.net
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Author: "maxwelltl54" <heirloomi@...> Time: Fri Oct 8, 2004 7:01 pm PDT Link
"If I were the FAA, I would not certify it at 1950 unless the
builder/pilot had done extensive flight testing and had
documentation to prove it. I wonder if all that was done here?"
These are experimental aircraft not certificated aircraft. The FAA
does not certify them for other than "airworthiness" which means no
grossly obvious building issues and all paperwork completed. Besides
how could the inspector know what the numbers should be without
conducting tests him/herself? Besides, the "extensive flight
testing" you speak of doesn't even begin until after the
airworthiness certificate is issued. You as the builder and you alone
own what you put on the paperwork.
"What would an attorney do with a copy of "dumb question" if Maxwell
ever crashes?"
I work with attorneys quite often and I assure you that any lawyer
worth anything wouldn't need a web forum thread for such a case. I
guess theoretically every bit of evidence is useful, but if a web
thread makes or breaks a case, then there probably isn't much of a
case to start with.
My impression from what I read is that for most accidents there is
not a lot of gray area. It is usually pretty quickly determined
whether an accident is caused by equipment failure or pilot error. In
either case a good lawyer could make a case for negligence since the
owner both built the plane and is probably the one operating it.
Flying in GA aircraft has increased risks. We decide to take those
risks in exchange for the enjoyment of flying. Part of the enjoyment
is sharing the pride and thrill with others. In carrying passengers
we accept additional risks and the passengers accept some risks as
well. I guess the answer is to either fly alone (even then if you
plant your plane in someone's home or a school-yard your widow(er) is
going to be shedding those same litigation tears) or we can have each
passenger sign a lawyer approved liability release prior to stepping
near the aircraft. Even then, a good lawyer will rip you to shreds.
Learn as much as you can, be a cautious and safe pilot, do your
weights and balance meticulously :) , keep current, and make smart
decisions to minimize the risks, and the rest is up to chance. The
only 100% way to be sure you will never hurt someone in your plane
and get sued for it is to not fly.
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