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Mauledriver(at)nc.rr.com
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 Posted: Sat Jan 08, 2011 1:07 pm Post subject: Need the type of material for front wing spar (Sparweb, St |
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I would disagree on several points relative to the fuselage tank vs wing
tank. But I'm not an engineer so much skepticism is in order.
Seems the key question is whether this is 1-off sort of ferry mission or
is this a special built, long leg machine. A fuselage tank may be in
order for a 1-off mission followed by normal ops as a normal '10. A
wing tank might make more sense if the a/c is optimized for long legs
and possibly more than a single ferry type flight. Round the world can
be thought of as either I guess, so... what's next?
Anyway, a well designed set of wing tanks can actually allow the wing to
carry a heavier total load without a bigger spar or wing structure. As
I understand it, in turbulence, the wing will fail at the point where
the bending stress exceeds the strength of the spar. If the wings are
weightless and all the weight is in the fuselage (analogous to a big
fuse tank and no wing tanks), that point will be close to the junction
of the wing and fuselage. But the total load required to break the
spar will generally be much less than if the weight were spread out
along the entire span of the wing. Such a wing loading situation will
allow you to sustain much higher gust loads before wing failure. The
wing can be effectively made stronger by spreading the total load out
along the span. I know that's how it works in gliders and the effects
of this kind of span loading on the ride is quite noticeable when ridge
running at redline.
A large fuselage tank would expose you to lower gust limits, a worse
ride in turbulence, and just less capability. A span loaded wing is
the optimal way to go for load carrying, handling gust loads, and
probably for a smoother ride.
But I'm sure there are a lot of other factors that I'm not accounting for.
On a different front, engineering a good wing tank system seems like
quite a challenge. One approach that Maule uses for their long rang
tank option (and I'm sure many other a/c do too) may have some value in
terms of simplying the plumbing. That is, they use small transfer pumps
to move fuel to the main tank. I don't think they even guage the tip
tanks. I think the pumps actually run slower than normal fuel
consumption so to use them you turn them on some time after takeoff and
let them dump into the mains for some time. The original main tank
guaging and plumbing works as-is. But it's just one approach and it is
a high wing.
Bill "thinking how great it is to have a challenging goal" Watson
On 1/8/2011 2:40 PM, Neil & Sarah Colliver wrote:
| Quote: |
I would agree.
You just cannot guarantee the stresses you will encounter as the wx cannot be guaranteed. It's not just landing where you can get negative G. Would you purchase a plane not knowing if it had been overstressed?
I agree with William - add a fuselage ferry tank. An easy mod. Ties down& restraint is also easy. Gravity fed fuel. Easy to remove. On long trips easy and simple = safe.
I had long discussions with Vans. They did not say it would not work, but gave me sufficient reasons not to do it that way if there was any other way it could be done.
Neil
On 9/01/2011, at 8:05 AM, William Curtis wrote:
>
>
> Vijay,
>
> For this type of mission, IMHO, you are probably better of building a
> large fuselage tank rather than messing with the wing tanks or
> structure. In 2004 I followed the exploits of an "Earthrounder" in
> his Cessna 210. It was a standard 210 wtih a large fuselage mounted
> fuel tank and custom pumping system.
>
> http://www.N30EW.com/Moreplanepics.htm
>
> Fuselage tanks add less localized stress and are easier to engineer
> than adding/modyfing the wing tanks/structure.
>
> I have added some extra plumbing in my aircraft just in case I wanted
> some "additional range" I can add a fuselage mounted tank which can
> later be removed.
>
> http://wcurtis.nerv10.com/9XOther/RV10FuelPlumb.pdf
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Sat Jan 08, 2011 2:39 pm Post subject: Need the type of material for front wing spar (Sparweb, St |
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Keep in mind that several certified aircraft have gross wt increases
approved with tip tanks of around 20 gal each tip, and Cessna 310 has
huge tip tanks as its main fuel source. The Bonanza generally gets
around 200lb gw increase with tip tanks. Also keep in mind that the two
best range extending techniques are to reduce speed and power to about
110% of best L/D, say around 130 kts IAS, and to run as lean of peak as
the engine will tolerate at the power delivering that airspeed, probably
around 40-45% power. The speed will be pretty reasonable if you are
doing that IAS up in the low to mid-teens.
On 1/8/2011 3:05 PM, John Cox wrote:
| Quote: | This is a most valuable thread for RV-10 builders and certainly
interesting. First, I don't believe either Ken Krueger (not to be
confused with Ken Scott) will give any builder written guidance or
state such a modification as "VANS acceptable". Some will then pipe
up, "This is why we are building Experimental Kit Approved". Is this
an initial construction feature (before Airworthiness Authorization)
during the build or is this a Mod to an approved FAA kit that has
flown? Extended Range Tanks whether Temporary (removable) or permanent
structural modification are issues beyond all but a few of VANS
clients. Good Luck Kelly with the guy from the Big Company. Most know
on this list I love modifications during initial build.
If the tanks seen at SNF were indeed John Nys, then Jesse and a few
others on this list might just remember our review of his products a
few years back at OSH. Get his DER's approval so it is U.S. of A, FAA
compliant. Oh yeh, since it is not Certificated, get Joe Norris of the
EAA to give their blessing. If a builder in another country tackles
the task get your country's aviation authority approval. Consider Spin
Testing and Wing Loading Tests as well. Here on this side of the pond,
FAA regulations were altered at the behest of the DEA (Drug
Enforcement Agency) to document or invalidate approved airworthiness
certificates when someone tries to modify the mission by extending the
fuel supply. Don't get me wrong, I am all for the Colliver's effort
and for others to take this model on a globe trotting tour. I also
want them to come back and share the journey with us without a Dan
Lloyd type moment. Tank placement, fuel flow, structural
considerations and metallurgy go far beyond a takeoff and landing
under normal "Utility" considerations. 3.8 g's and a 1.5x safety
factor might be placing the test pilot in unintended outcomes. The
fact that this unintended load is over the arbitrary CG point is not
as relevant and it sounds.
I actually trained pilots back decades ago to make the Round the World
Balloon Crossing a reality. One effort toward that dream fell short
when the pilot (Steve Fossett) ran into a Thunderstorm in the Southern
Hemisphere. By the way he did finally make it but lost his life years
later on a routine flight out here on the west coast. Another friend
and a copilot were lost in a thunderstorm over the Med just a few
months ago in the Gordon Bennett reenactment. That was Ben Abruzzo's
son Richard. Ben was the first to cross the Atlantic in the Double
Eagle II and then died when his twin engine aircraft ran out of gas
months later. Maxie Anderson was another from the Double Eagle II
flight at went west after a flight with Don Ida over Germany. Mother
Nature awaits the daring in all of us. Plan for arriving wiser and
more humble.
High wing loading during CAT (clear air turbulence) or control surface
flutter at higher TAS (a passionate topic for K. Scott) could bring
additional excitement to the pursuit.
The wingspar in the RV-10 (a design extended from an earlier smaller
VANS aircraft), its web and its extension do not lend themselves to
such a needed successful conclusion. Just because someone can do it,
has done it, and has not YET had a problem doe not assure that you
could ever get it approved following existing regulations and proper
airworthiness channels. Let us know if it is successful. Our prayers
and aspirations will be with you.
Good Luck, land safely with all passengers aboard.
John Cox
------------------------------------------------------------------------
Also, I think in was in an RVator article a while back, where I
believe Ken Krueger alluded (reluctantly) that “if you had to add
extra fuel capacity” to an RV, add temporary fuselage tanks rather
that additional fuel in the wings. This was because additional mass
in the wings can add unpredictable negative spin characteristics to
the aircraft.
--
William
N40237 - http://wcurtis.nerv10.com/
On Sat, Jan 8, 2011 at 2:40 PM, Neil & Sarah Colliver
<ncol(at)xtra.co.nz> wrote:
>
>
> I would agree.
>
> You just cannot guarantee the stresses you will encounter as the wx
cannot be guaranteed. It's not just landing where you can get negative
G. Would you purchase a plane not knowing if it had been overstressed?
>
> I agree with William - add a fuselage ferry tank. An easy mod. Ties
down & restraint is also easy. Gravity fed fuel. Easy to remove. On
long trips easy and simple = safe.
>
> I had long discussions with Vans. They did not say it would not
work, but gave me sufficient reasons not to do it that way if there
was any other way it could be done.
>
> p; - The RV10-List Email Forum
href="http://www.matronics.com/Navigator?RV10-List">http://www.matronic-->
http://forums.matronics.com <http://forums.matronics.com/>
p; - List Contribution bsp; -Matt Dralle, List
href="http://www.matronics.com/contribution">http://www.matronics.com/c=================
*
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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
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vijaypisini(at)yahoo.com
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| Posted: Sat Jan 08, 2011 3:15 pm Post subject: Need the type of material for front wing spar (Sparweb, St |
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Bill,
Thanks for the input. Yes, this will most likely will NOT be a one-off round
the world trip. There will be more trips where I'll be using the long range
tanks and in those cases outboard wing tanks are best.
I replied to some of the mails detailing as to why I prefer some fuel in the
outboard wing tanks versus all of the fuel in ferry tanks at the back.
Wing tank positives:
Less CG problems
Less wing gust problems (stress concentration on wing and fuselage joint) on
overweight legs
Can use them for more of the long range trips
More space inside the plane
Ferry tank positives:
Less modification issues
Not changing the original kit design (for resale problems)...hence less worries
as some put it
Less detrimental effect when it gets into a spin
My fuel management design in words:
4 fuel valve selectors (left, original center, right and aft). Left and Right
valves (like the valve in Piper Arrow) are going to be similar to each other
with the pointer either on outboard tank or on inboard tank depending on the
need. Outboard tank fuel flow plumbing will be similar (in concept) to original
inboard tank up until the side valves (left, right). Original center fuel valve
will have the options as left, right and off. The aft fuel valve will will have
selections as tank1 and tank2 (for right seat and rear seat tanks). I intend to
keep all the fuel selectors permanently in the plane.
Ferry tank fuel will be drained (by gravity and also there will be a pump for
each tank...I'll be using Turtlepac tanks as ferry tanks) into the left main
tank (additional plumbing will be done for this)...no guage for the ferry fuel
tanks. There will be guages (fuel senders) for outboard tanks. I will have to
deal with engine coughing only twice for the two outboard tanks when I run them
dry. That problem will not be there for ferry tanks as the fuel drains into the
left main tank. After take off on left inboard tank, I'll be using the outboard
tanks first for 5-6 hrs of cruise flight by pointing the left and right valves
to outboard tanks and managing the original center valve as usual (left,
right). Once the outboard tanks are used up, I'll use both the ferry tanks
through the left inboard tank. For about 7-8 hrs, I just have to open and close
the ferry tanks until they are drained off completely. After this, I'll be on
the left and right inboard tanks with regular fuel selection until landing.
I decided against draining the outboard fuel tanks into the corresponding
inboard fuel tanks because I'll have to deal with the fuel pump and I don't want
to risk the failure of the fuel pump in this option. I want the plumbing to be
simple in concept as well. This (more fuel valves) was done by couple of people
already and it is simple in operation and is proven. I got to be careful while
draining the fuel from ferry tanks into the left inboard tank...not to overfill
the left inboard tank.
I'm prepared for the extra work...!
Vijay
---
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