Weight an Balance
Eddie
Specifically, are you in the aerobatic envelope or do you go out the
aft limit with two people? Thanks, Eddie
FrancoisMarquis
I'll try to include a Excel spreadsheet ( Eagle II WB.xls ) that
illustrate the effect of a passenger, vs fuel, vs cg. Simply adjust
the basic numbers to your own reality, et voilà!
Francois
David Wolf
!!!
Ashley Messenger
My airplane remains in CG with two reasonably sized people and about half
fuel. I weigh 220, about 240 with parachute and can stay in the aerobatic
envelope with a 180lb passenger and half fuel.
I have carried a 310lb passenger in the front, and we were out of the aft
limit by about 1/2 inch, but the airplane didn't display any bad habits. Of
course, I didn't spin it in that condition, but we did loop and roll.
The airplane is a stock Eagle with a B&C starter and standard alternator.
I put the weight and balance formula in an Excel spreadsheet, so it makes it
very easy to run what-if scenarios. There is a persistent wive's tale out
there about the Eagle having an aft CG problem, but it just is not so unless
the design has been altered.
Ashley Messenger
N180MD
FrancoisMarquis
I ran your numbers into my spreadsheet. From your scenario, consider
oil and unusable fuel and your plane needs to be 1010 pounds empty
with empty CG arm at 88.6 inches??? Your aircraft is exceptionally
light to me and your empty CG seems quite forward. But given these
numbers, a 310 pounds passenger still puts you way way outside the
envelope.
There must be more than design alterations to explain such
differences...
Cheers!
Francois
PS: You can find my calculator spreadsheet in the file section under
Eagle II WB.xls
On Mar 27, 7:27 am, "Ashley Messenger" <amsnapr...@zoomtown.com>
wrote:
David Wolf
failure from high weight combined with high G (usually from exiting a loop
at high speed).
It is the autorotational maneuvers which are mainly affected, and they can
show you some pretty exciting stuff.
Dave
-----Original Message-----
From: Christe...@googlegroups.com
[mailto:Christe...@googlegroups.com] On Behalf Of FrancoisMarquis
Sent: Thursday, March 27, 2008 8:42 PM
To: Christen-Eagle
David Wolf
inadvertently, usually at low airspeed when torque/precession dominate,
usually seen when a hammerhead goes bad.
Jam...@fcstone.com
I think you have bad data in the calculation of your weight and balance. I too have the light weight starter - but I have the battery moved forward under the gas tank and with a 240 pound pilot and 180 pound passenger I would not be within the aerobatic envelope regardless of fuel quantity.
Another flaw in your thinking is by going with only half fuel when loaded this heavy and wanting to do aerobatics. Fill the fuel tank and the CG will move forward. No matter what you do, the Eagle continues to move its CG aft as you burn fuel - If I was going to do aerobatics outside of the CG limit, I would rather do them heavy with the CG more forward than with half fuel and the CG out aft.
James M. Burr
Vice President
FCStone Trading, LLC
816-457-6217 (direct)
816-550-3843 (cell)
"The wise man is the man who knows that he doesn't know." - Socrates 470-399 BC
This data and these comments are provided for information purposes only and are not intended to be used for specific trading strategies. Although all information is believed to be reliable, we cannot guarantee its accuracy or completeness. Commodity trading involves risks, and you should fully understand those risks before trading.
| "Ashley Messenger"
<amsna...@zoomtown.com>
Sent by: Christe...@googlegroups.com 03/27/2008 06:27 AM |
|
|
FrancoisMarquis
normal and accelerated. I can appreciate the fact that on such
recovery attempt, while correct control inputs are applied, the
unusual response delay can seed doubt in one's mind and urge one to
try anything else, including bail-out.
Bear in mind that a large percentage NTSB fatalities in Pitts/Eagle
are spin related with two competent pilots on board... Your mileage
may vary.
Francois
David Wolf
I don’t do out of envelope aerobatics anymore since my eyes got watered. However, one might consider rolls and loops to be normal flight as far as airplane stresses and aerodynamics go. If one is out of CG/weight box for aerobatics, when doing these maneuvers one should strictly sustain such docile flight conditions. If one cannot assure this against the odds of losing ones airplane (or life) one should not fly such maneuver outside the box. And strictly speaking, one shouldn’t in any case.
All must introspect carefully.
Dave
<br
FrancoisMarquis
Thanks for that pearl of wisdom. Please stop trolling the people in
here. They deserve better.
Francois
On 30-Mar-08, at 10:54 , Ashley Messenger wrote:
>>No, I am telling you that I fly the aircraft outside the akro envelope on a regular basis.
On 30-Mar-08, at 10:16 , Francois Marquis wrote:
>>Nope. You are saying that you are flying akro within the envelope and you support that affirmation with data that proves you are outside the envelope, while >>agreeing with my calculations???
>>
>> No, I'm not sure I understand what you are telling me.
>>
>>F
On 30-Mar-08, at 08:07 , Ashley Messenger wrote:
>>Francoise
>>
>>I include unsuable fuel and oil in the empy weight, but that difference is minor.
>>
>>Otherwise, your calculations are completly correct. Do you understand what I am telling you?
>>
>>Ashley
On 29-Mar-08, at 22:11 , Francois Marquis wrote:
>>Ashley,
>>
>>I am sorry but we are not on the same page.
>>
>>1060 + 84 + 6 (unusable fuel, you count that one, right?) + 200 + 240 is 1570. Right there you are outside the envelope, max gross akro is 1520.
>>
>>At 90.06 empty, once loaded that puts your new CG at 100.43 Akro aft CG at gross is 99.6
>>
>>I think we are not calculating with the same data...
>>
>>Cheers!
>>
>>Francois
On 28-Mar-08, at 10:59 , Ashley Messenger wrote:
>>Francois
>>
>>Yep, a 310lb passenger puts me way out of the envelope! My airplane is 1060 empty, 90.06 CG. It has the Hartzell propeller and full size alternator with the B&C >>starter. I am in the envelope with me at 240lbs and a 200lb passenger, 14 gallons fuel.
>>
>>Knowing that a heavy front seater puts me out the after limit, I will still give an acro ride with the proviso of no spins and a 3G limit, and very limited negative, say >>a reverse half Cuban.
>>
>>The airplane exhibits no bad habits in that range. In an attempt to reduce the overall weight, people often install light propellers and lightweight accessories that >>shift their empty CG aft. I flew one that had a fixed-pitch prop, and while light, the builder had to resort to all manner of alchemy to bring the CG in range, and the >>airplane ended up being restricted to a 180lb rear seat load.
>>
>>Ashley