Today's Message Index:
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1. 12:50 AM - Re: Aluminum Fuel Tank for MIII (icrashrc)
2. 07:13 AM - Re: Re: Aluminum Fuel Tank for MIII (John Hauck)
3. 07:22 AM - Re: Re: Aluminum Fuel Tank for MIII (b young)
Message 1
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| Subject: | Re: Aluminum Fuel Tank for MIII |
John,
This post leads to a question I've been meaning to ask for a while now. Have you
done a weight & balance lately on your plane with it loaded up and ready for
a trip? I'm hoping to get an idea of acceptable CG range so i have some idea
of where to start during flight testing. Thank you,
Scott
And yes, let's make it clear that whatever range you post is suitable for YOUR
aircraft only!
[quote="John Hauck"]For what it is worth, I have a 25 gal aluminum fuel tank in
my mkIII. Don't know how much the tank weighs, but it carries 150 lbs of fuel.
In addition to that, I carry aprx'ly 125 lbs of gear under the fuel tank
in my cargo compartment. To top it off, I have a 12 lb Maule Tundra Tailwheel,
8" pneumatic, mounted, in addition to a 912ULS with a 4" prop extension
and a 3 blade WD Prop with nickle steel leading edges.
My mkIII flies well. Extreme testing in every attitude, normal and unusual,
I could think of indicates it does not have an aft cg problem. Just completed
a 60.2 hour flight over 18 days in some of the most difficult flying conditions
I have encountered in 25 years of doing serious cross country flights in
Kolb aircraft. Extreme cross winds, 6500 ft field elevations, 9300 ft density
altitude, and dust devils, all encountered at the same time by three intrepid
Kolb mkIII adventurers in Grants, NM. I might add, my mkIII was at its max
gross weight of 1200 lbs during this time frame.
The leading edge of my horizontal stabilizer is positioned below the standard
position in the plans. Experimentation indicates it is now in a "sweet spot"
for best cruise flight with or without a passenger. We installed adjustable
attachments to accomplish this during the fabrication phase of the fuselage
at the Kolb Factory in 1991, along with the 25 gal fuel tank.
The major difference between my mkIII and a plans built mkIII is position of
the main landing gear, which places the axles 8" forward of the stock location.
This will offset aft cg a tad, but not much at its location near the cg.
I emphasize, this is how I configured my mkIII and it works great for me. I
don't recommend others follow suit.
john h
mkIII
> From: ross richardson (smlplanet@msn.com)
>
>
> I am wanting to build a larger gas tank also but one thing I haven't seen
or addressed is W&B with more weight being shifted to the rear. I have a Mark
IIIC with a 912 UL and the factory two 5 gal tanks and had to install the
adjustable forward horz stablizer brkts for duel flight. I am installing
an electric horz stablizer trim system now so as not to have to change
the pin locations for solo and duel operations. That have you had to do to
address this problem with the larger gas tanks?
>
> [b]
--------
Scott
www.ill-EagleAviation.com
do not archive
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=247398#247398
Message 2
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| Subject: | Re: Aluminum Fuel Tank for MIII |
> This post leads to a question I've been meaning to ask for a while now.
Have you done a weight & balance lately on your plane with it loaded up and
ready for a trip? I'm hoping to get an idea of acceptable CG range so i have
some idea of where to start during flight testing. Thank you,
>
> Scott
I haven't done a weight and balance in a some time.
I am sure the results would be very interesting.
However, there has been extensive flight testing which indicates forward and
aft cg are in an acceptable range.
I'd be glad to let you do a weight and balance on my mkIII. I don't have
scales or a good place to do one now.
john h
mkIII
Message 3
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| Subject: | Re: Aluminum Fuel Tank for MIII |
Denny
As I remember there are 3 tubes behind the seats that have to come out to
install the tank. When I ordered the cage they made provisions for the
tubes to be removed. There are tubes that come from either side of the
boom tube that join at the center of a cross over tube at the center behind
the two seats, and one tube from the boom tube area to the left corner
behind the seats. The first two they welded at the factory a small tab on
the tubes so we could drill a hole and install a bolt to get them in and
out. the third has a small sleeve that goes over where the tube was cut at
top and bottom and the sleeve is riveted to the stubs at both ends and also
the tube. The tank slides back into the area just behind the seats and
sits on the same diagonal tubes that support the plastic tank tray. On
the sides of the diagonal tubes there are some tabs welded down, and there
is some aluminum angle welded to the bottom of the tank that bolts to the
tabs. I drilled the holes in the alum angles a bit over sized and inserted
a rubber bushing in the hole and also have a rubber washer on both sides of
the angle, this gives the tank a rubber mount to help eliminate vibrations
from cracking things. The tank has a curve cut into the bottom to go
around and over the aileron torque tube. So there are 2 outlets on the
bottom that have to be connected together to get all the fuel out of the
tank. John h tank fits in the area behind his head where mine is behind
the seats. He has the area behind the seats for storage,, I use the area
above the tank for storage. And he carries 9 more gallons than I do.
If you have any other questions I can try and explain or send photos.
Boyd
>>>>>>>>>>>>>>>>>>>>>>>..
Boyd,
Does your tank install from behind the seats like the new xtra tank?
I saw Kolbs online video of installing a big tank in the Xtra and was
wondering if the regular Mk-3 had the same option.
Denny Rowe
I bought the 16 gal alum fuel tank that was a factory option in 1998. when
doing W&B on my mkIIIC I determined the cg of the fuel tank is verrrrry
close to the rear cg limit. When flying solo I am near the rear cg,
from full to empty fuel, the cg does not move more than a quarter inch.
When I am flying with a passenger, my cg is closer to the center of the
range, and as I burn off fuel the cg will creep forward. Even at empty
tanks I am well within the limits, so to answer your question "That have
you had to do to address this problem with the larger gas tanks? " there is
no problem with my set up. Now if your fuel tank installs further aft
than mine does. You will have to do the math.
Boyd young
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