Author: "mikeje101" <mikeje@...> Time: Mon Jan 7, 2002 10:09 pm PST Link
I am starting a 7 and plan to use a subaru engine capable of
producing 225 hp up to 25000 ft. At that power, and at .42 lbs/hr I
will be burning 16.5 gal/hr. For extra fuel, I am contemplating
additional fuel tanks outboard of the originals: either 2 additional
full size leading edge tanks or partial tanks plumbed into the
originals or with seperate feed lines. Full size tanks would yield 84
gallons and 500lb, making it a solo flight. Comments and suggestions?
I am a long way from this decision, but want to make an informed,
well thought out choice.
Mike Endersby
Author: "robert_paisley" <robert@...> Time: Mon Jan 7, 2002 10:58 pm PST Link
At 12,000 ft you will go over 200mph with 120HP (IO-360 power at
12,000 ft) and burn about 10 GPH (maybe 8GPH with the Subaru). Are
you sure you need the extra fuel?
Robert Paisley
--- In RV7and7A@y..., "mikeje101" <mikeje@a...> wrote:
> I am starting a 7 and plan to use a subaru engine capable of
> producing 225 hp up to 25000 ft. At that power, and at .42 lbs/hr I
> will be burning 16.5 gal/hr. For extra fuel, I am contemplating
> additional fuel tanks outboard of the originals: either 2
additional
> full size leading edge tanks or partial tanks plumbed into the
> originals or with seperate feed lines. Full size tanks would yield
84
> gallons and 500lb, making it a solo flight. Comments and
suggestions?
> I am a long way from this decision, but want to make an informed,
> well thought out choice.
>
> Mike Endersby
Author: "mikeje101" <mikeje@...> Time: Tue Jan 8, 2002 12:19 pm PST Link
Robert:
I plan to exceed the redline by quite a bit. At 8000 ft the power
increase works out to a little over 240mph and a 2 knot gain for
every 1000 ft is an extra 40mph. I probably won't fly over 18000 for
a cruise of 265 or so.
I think the control surfaces could be improved for better
stiffness, and I might possibly rebuild them entirely out of carbon
fiber for that reason. Flutter is the issue, but remember they made
most of these without a counterbalanced rudder.
One other thought: A slightly overbalanced (.5 oz??)control
surface would tend to return the structure to its neutral point if
flutter were induced instead of reinforcing the vibration to
destruction. Is this reasonable or does it set up oscillations in the
structure anyway, just opposite of the initial bending or vibration?
--- In RV7and7A@y..., "robert_paisley" <robert@p...> wrote:
> At 12,000 ft you will go over 200mph with 120HP (IO-360 power at
> 12,000 ft) and burn about 10 GPH (maybe 8GPH with the Subaru). Are
> you sure you need the extra fuel?
> Robert Paisley
>
> --- In RV7and7A@y..., "mikeje101" <mikeje@a...> wrote:
> > I am starting a 7 and plan to use a subaru engine capable of
> > producing 225 hp up to 25000 ft. At that power, and at .42 lbs/hr
I
> > will be burning 16.5 gal/hr. For extra fuel, I am contemplating
> > additional fuel tanks outboard of the originals: either 2
> additional
> > full size leading edge tanks or partial tanks plumbed into the
> > originals or with seperate feed lines. Full size tanks would
yield
> 84
> > gallons and 500lb, making it a solo flight. Comments and
> suggestions?
> > I am a long way from this decision, but want to make an informed,
> > well thought out choice.
> >
> > Mike Endersby
Author: Paul Besing <azpilot@...> Time: Tue Jan 8, 2002 12:30 pm PST Link
265 MPH? That is WELL beyond the VNE that Van's
publishes. One pocket of turbulence at that speed and
your day could be ruined in a flash. Have you ever
flown an RV at 195 MPH and hit turbulence? It is
painful. I have hit some unexpected turbulence (the
air was perfectly smooth before)while going that fast
and I slammed my head into the canopy and thought the
freaking wings were going to come right off. I was
holding my stick grip and it came off of the stick I
was jerked so hard.
My bet is that carbon fiber control surfaces or not,
the wing loading would not be able to handle an RV at
that speed in the event of any wind shear/turbulence.
Be careful.
=====
Paul Besing
RV-6A 197AB Arizona
http://www.lacodeworks.com/besing
First Flight 7/22/01
Kitlog Pro Builder's Log Software
http://www.kitlog.com
__________________________________________________
Do You Yahoo!?
Send FREE video emails in Yahoo! Mail!
http://promo.yahoo.com/videomail/
Author: "Collins, Bob" <bcollins@...> Time: Tue Jan 8, 2002 12:34 pm PST Link
>My bet is that carbon fiber control surfaces or not,
>the wing loading would not be able to handle an RV at
>that speed in the event of any wind shear/turbulence.
I'll bet the tail comes off first.
BC
Author: "robert_paisley" <robert@...> Time: Tue Jan 8, 2002 12:50 pm PST Link
Mike,
Have you looked at the Lancair products? It sounds like your mission
profile is more similar to their design goals than those of the RV.
Robert
--- In RV7and7A@y..., "mikeje101" <mikeje@a...> wrote:
> Robert:
> I plan to exceed the redline by quite a bit. At 8000 ft the power
> increase works out to a little over 240mph and a 2 knot gain for
> every 1000 ft is an extra 40mph. I probably won't fly over 18000
for
> a cruise of 265 or so.
> I think the control surfaces could be improved for better
> stiffness, and I might possibly rebuild them entirely out of carbon
> fiber for that reason. Flutter is the issue, but remember they made
> most of these without a counterbalanced rudder.
>
> One other thought: A slightly overbalanced (.5 oz??)control
> surface would tend to return the structure to its neutral point if
> flutter were induced instead of reinforcing the vibration to
> destruction. Is this reasonable or does it set up oscillations in
the
> structure anyway, just opposite of the initial bending or vibration?
>
> --- In RV7and7A@y..., "robert_paisley" <robert@p...> wrote:
> > At 12,000 ft you will go over 200mph with 120HP (IO-360 power at
> > 12,000 ft) and burn about 10 GPH (maybe 8GPH with the Subaru).
Are
> > you sure you need the extra fuel?
> > Robert Paisley
> >
> > --- In RV7and7A@y..., "mikeje101" <mikeje@a...> wrote:
> > > I am starting a 7 and plan to use a subaru engine capable of
> > > producing 225 hp up to 25000 ft. At that power, and at .42
lbs/hr
> I
> > > will be burning 16.5 gal/hr. For extra fuel, I am contemplating
> > > additional fuel tanks outboard of the originals: either 2
> > additional
> > > full size leading edge tanks or partial tanks plumbed into the
> > > originals or with seperate feed lines. Full size tanks would
> yield
> > 84
> > > gallons and 500lb, making it a solo flight. Comments and
> > suggestions?
> > > I am a long way from this decision, but want to make an
informed,
> > > well thought out choice.
> > >
> > > Mike Endersby
Author: "mikeje101" <mikeje@...> Time: Tue Jan 8, 2002 3:33 pm PST Link
Robert:
No doubt, but their's is 42,900 to get started. I got started
with 1300 for a balanced rv6 tail and complete new Avery tool set.
And I want to land slow. I'm taking the experimental part of this
seriously! :)
Mike
--- In RV7and7A@y..., "robert_paisley" <robert@p...> wrote:
> Mike,
> Have you looked at the Lancair products? It sounds like your
mission
> profile is more similar to their design goals than those of the RV.
> Robert
>
> --- In RV7and7A@y..., "mikeje101" <mikeje@a...> wrote:
> > Robert:
> > I plan to exceed the redline by quite a bit. At 8000 ft the power
> > increase works out to a little over 240mph and a 2 knot gain for
> > every 1000 ft is an extra 40mph. I probably won't fly over 18000
> for
> > a cruise of 265 or so.
> > I think the control surfaces could be improved for better
> > stiffness, and I might possibly rebuild them entirely out of
carbon
> > fiber for that reason. Flutter is the issue, but remember they
made
> > most of these without a counterbalanced rudder.
> >
> > One other thought: A slightly overbalanced (.5 oz??)control
> > surface would tend to return the structure to its neutral point
if
> > flutter were induced instead of reinforcing the vibration to
> > destruction. Is this reasonable or does it set up oscillations in
> the
> > structure anyway, just opposite of the initial bending or
vibration?
> >
> > --- In RV7and7A@y..., "robert_paisley" <robert@p...> wrote:
> > > At 12,000 ft you will go over 200mph with 120HP (IO-360 power
at
> > > 12,000 ft) and burn about 10 GPH (maybe 8GPH with the Subaru).
> Are
> > > you sure you need the extra fuel?
> > > Robert Paisley
> > >
> > > --- In RV7and7A@y..., "mikeje101" <mikeje@a...> wrote:
> > > > I am starting a 7 and plan to use a subaru engine capable of
> > > > producing 225 hp up to 25000 ft. At that power, and at .42
> lbs/hr
> > I
> > > > will be burning 16.5 gal/hr. For extra fuel, I am
contemplating
> > > > additional fuel tanks outboard of the originals: either 2
> > > additional
> > > > full size leading edge tanks or partial tanks plumbed into
the
> > > > originals or with seperate feed lines. Full size tanks would
> > yield
> > > 84
> > > > gallons and 500lb, making it a solo flight. Comments and
> > > suggestions?
> > > > I am a long way from this decision, but want to make an
> informed,
> > > > well thought out choice.
> > > >
> > > > Mike Endersby
Author: "mikeje101" <mikeje@...> Time: Tue Jan 8, 2002 3:41 pm PST Link
Paul:
No, I haven't. And I can see your point. The lower wing loading
makes turbulence much more of a problem than it would be in a legacy
with much less wing area even though it is stressed for I think 4.4
g's. What do the harmon rocket guys say? Don't they use the rv4 wing
and strap on a 540 and cruise at 250?
Mike
--- In RV7and7A@y..., Paul Besing <azpilot@e...> wrote:
> 265 MPH? That is WELL beyond the VNE that Van's
> publishes. One pocket of turbulence at that speed and
> your day could be ruined in a flash. Have you ever
> flown an RV at 195 MPH and hit turbulence? It is
> painful. I have hit some unexpected turbulence (the
> air was perfectly smooth before)while going that fast
> and I slammed my head into the canopy and thought the
> freaking wings were going to come right off. I was
> holding my stick grip and it came off of the stick I
> was jerked so hard.
>
> My bet is that carbon fiber control surfaces or not,
> the wing loading would not be able to handle an RV at
> that speed in the event of any wind shear/turbulence.
>
> Be careful.
> =====
> Paul Besing
> RV-6A 197AB Arizona
> http://www.lacodeworks.com/besing
> First Flight 7/22/01
> Kitlog Pro Builder's Log Software
> http://www.kitlog.com
>
> __________________________________________________
> Do You Yahoo!?
> Send FREE video emails in Yahoo! Mail!
> http://promo.yahoo.com/videomail/
Author: "mikeje101" <mikeje@...> Time: Tue Jan 8, 2002 3:44 pm PST Link
A legacy will do 280 at 18000 and is stressed for 4.4 g's I believe.
Is it stronger or just stiffer to resist flutter better? What about
the harmon rocket guys? They report cruise around 250 with their
modified rv4's.
Mike
--- In RV7and7A@y..., "Collins, Bob" <bcollins@m...> wrote:
>
> >My bet is that carbon fiber control surfaces or not,
> >the wing loading would not be able to handle an RV at
> >that speed in the event of any wind shear/turbulence.
> I'll bet the tail comes off first.
>
> BC
Author: "B. Tomm" <fvalarm@...> Time: Wed Jan 9, 2002 12:02 pm PST Link
Mike,
The RV7 is already a well thought out aircraft. It comes from good
engineering, lots of experience, and testing to confirm the engineering. I
wonder why you would risk spoiling what has already been achieved with the
aircraft, as it already does so many things so well. Remember that whenever
you have a given machine that operates as a balance within the laws of
physics, everything is a compromise. Don't plan to exceed the VNE and still
expect to call it an airplane after landing.
Just my 2.5 cents worth in the name of responsible (long term) aviating.
BT
Author: "Phil Birkelbach" <phil@...> Time: Wed Jan 9, 2002 3:00 pm PST Link
I agree. I think it was Michael Collins who said, "The laws of aerodynamics are unforgiving, and the ground is hard!"
Exceeding Vne is something (in my opinion) that should be approached with a VERY large amount of caution. I am not an aerodynamicist but I would not think that converting control surfaces to Carbon fiber would help flutter. It might make it worse, and without making heavy modifications to the airframe nothing will help the wing loading issue. These are things that engineers, wind tunnels and professional test pilots should do.
There was a very good article on manuevering speed in the RVator a couple of issues back. The context of the article was on why putting a 180HP engine in an RV-9 was not the best idea, but as always Van did an excellent job of explaining the implications of exceeding Va and Vne and why the former is a bad idea in turbulence and the later is a bad idea period. Remember once you pass Va you can break the airplane with the control stick, pass Vne and God may break it for you.
Godspeed,
Phil Birkelbach
RV-7 - N727WB (Reserved) - http://www.myrv7.com
Houston, Texas
Flaps - Fuse ordered
Takeoffs are optional, Landings are mandatory.
----- Original Message -----
From: B. Tomm
To: RV7and7A@yahoogroups.com
Sent: Tuesday, January 08, 2002 11:27 PM
Subject: Re: [RV7and7A] additional fuel
Mike,
The RV7 is already a well thought out aircraft. It comes from good
engineering, lots of experience, and testing to confirm the engineering. I
wonder why you would risk spoiling what has already been achieved with the
aircraft, as it already does so many things so well. Remember that whenever
you have a given machine that operates as a balance within the laws of
physics, everything is a compromise. Don't plan to exceed the VNE and still
expect to call it an airplane after landing.
Just my 2.5 cents worth in the name of responsible (long term) aviating.
BT
Yahoo! Groups Sponsor
ADVERTISEMENT
Van's Air Force - World Wide Wing
www.vansaircraft.net
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
Author: "Collins, Bob" <bcollins@...> Time: Wed Jan 9, 2002 3:02 pm PST Link
Yeah, and just for the record for those folks who are considering this idea.
Please remember: That might be my kid in that house down there....or in the
schoolyard...or wherever else you and your plane will come down.
Is it any wonder why people are so anxious to shut down airports and the
people who fly GA? They don't need to come up with reasons, we give 'em
enough on our own.
Bob Collins
St. Paul, Mn.
-----Original Message-----
From: Phil Birkelbach [mailto:phil@p...]
Sent: Wednesday, January 09, 2002 5:00 PM
To: RV7and7A@yahoogroups.com
Subject: Re: [RV7and7A] additional fuel
I agree. I think it was Michael Collins who said, "The laws of aerodynamics
are unforgiving, and the ground is hard!"
Exceeding Vne is something (in my opinion) that should be approached with a
VERY large amount of caution. I am not an aerodynamicist but I would not
think that converting control surfaces to Carbon fiber would help flutter.
It might make it worse, and without making heavy modifications to the
airframe nothing will help the wing loading issue. These are things that
engineers, wind tunnels and professional test pilots should do.
There was a very good article on manuevering speed in the RVator a couple of
issues back. The context of the article was on why putting a 180HP engine
in an RV-9 was not the best idea, but as always Van did an excellent job of
explaining the implications of exceeding Va and Vne and why the former is a
bad idea in turbulence and the later is a bad idea period. Remember once
you pass Va you can break the airplane with the control stick, pass Vne and
God may break it for you.
Godspeed,
Phil Birkelbach
RV-7 - N727WB (Reserved) - http://www.myrv7.com
Houston, Texas
Flaps - Fuse ordered
Takeoffs are optional, Landings are mandatory.
----- Original Message -----
From: B. Tomm
To: RV7and7A@yahoogroups.com
Sent: Tuesday, January 08, 2002 11:27 PM
Subject: Re: [RV7and7A] additional fuel
Mike,
The RV7 is already a well thought out aircraft. It comes from good
engineering, lots of experience, and testing to confirm the engineering.
I
wonder why you would risk spoiling what has already been achieved with the
aircraft, as it already does so many things so well. Remember that
whenever
you have a given machine that operates as a balance within the laws of
physics, everything is a compromise. Don't plan to exceed the VNE and
still
expect to call it an airplane after landing.
Just my 2.5 cents worth in the name of responsible (long term) aviating.
BT
Yahoo! Groups Sponsor
ADVERTISEMENT
Van's Air Force - World Wide Wing
www.vansaircraft.net
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
Van's Air Force - World Wide Wing
www.vansaircraft.net
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/