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#11
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Measurement of CofG
Why don't the manufactures publish the height to raise the tail as a
difference between the axle center lines above ground? Then you don't need to cut or calculate. Oh, gee... That'd be too simple. "Hagbard Celine" wrote in message ... If the shop has a digital protractor you could also convert the rise/ run to degrees, put the protractor on the specified part of the tail boom and raise the tail until it reads the correct angle. Arctan(rise/run) = angle in degrees About 2.1 degrees, sloping down towards the tail in this case. |
#12
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Quote:
Same question, hopefully same answer...could use a little more info. I'm trying to put together a W&B event at our club, we're bringing in outside help from another club with a set of scales and the experience of knowing what to do. WRT positioning the glider at the correct angle, my ship is an ASW-19b. Although my owners manual has a page dedicated to CG info, there's nothing in there about what procedure to use to actually weigh the thing. It's just a page with a CG envelope on it. Now I did find on page 30 of the manual (a page that has general dimensions as well as specs for control deflections) a side view drawing with info presented as the thread starter discussed, mine says 1000 by 45. SO, to do the procedure correctly, construct a small triangle with those dimensions, inflate the main wheel to proper pressure, put a level on the triangle, then raise the tail till I get a level bubble? It would seem to make sense that this is done with wings level laterally as well, correct? Lightly (fingertips) or is a wingstand under a tip ok? THEN, take the weights? Finally, this will be the 4th W&B for this glider. All the ones done previously have had a "form" with a glider drawing on it and appropriate spots to fill in main wheel/tail wheel weights, etc. Where can we obtain "blanks" to fill in our ships for our event? We will have an A&P IA overseeing the process and signing off logbooks. As I said, I'm coordinating, so I'm trying to get all the info/materials each owner will need to have on hand at weigh-in so the event goes smoothly. Thanks much, Rob ASW-19b ZAP Ps-sorry if this double posts... |
#13
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Measurement of CofG
I am sure I am not on my own when I say I have an Excel spreadsheet with
the calculations for C of G to be done. It may not be pretty but it does the job. If you want a copy email me. Croft At 04:51 12 January 2012, RAS56 wrote: Hagbard Celine;807559 Wrote: If the shop has a digital protractor you could also convert the rise/ run to degrees, put the protractor on the specified part of the tail boom and raise the tail until it reads the correct angle. Arctan(rise/run) = angle in degrees About 2.1 degrees, sloping down towards the tail in this case. Same question, hopefully same answer...could use a little more info. I'm trying to put together a W&B event at our club, we're bringing in outside help from another club with a set of scales and the experience of knowing what to do. WRT positioning the glider at the correct angle, my ship is an ASW-19b. Although my owners manual has a page dedicated to CG info, there's nothing in there about what procedure to use to actually weigh the thing. It's just a page with a CG envelope on it. Now I did find on page 30 of the manual (a page that has general dimensions as well as specs for control deflections) a side view drawing with info presented as the thread starter discussed, mine says 1000 by 45. SO, to do the procedure correctly, construct a small triangle with those dimensions, inflate the main wheel to proper pressure, put a level on the triangle, then raise the tail till I get a level bubble? It would seem to make sense that this is done with wings level laterally as well, correct? Lightly (fingertips) or is a wingstand under a tip ok? THEN, take the weights? Finally, this will be the 4th W&B for this glider. All the ones done previously have had a "form" with a glider drawing on it and appropriate spots to fill in main wheel/tail wheel weights, etc. Where can we obtain "blanks" to fill in our ships for our event? We will have an A&P IA overseeing the process and signing off logbooks. As I said, I'm coordinating, so I'm trying to get all the info/materials each owner will need to have on hand at weigh-in so the event goes smoothly. Thanks much, Rob ASW-19b ZAP Ps-sorry if this double posts... -- RAS56 |
#14
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Measurement of CofG
I am sure I am not on my own when I say I have an Excel spreadsheet with
the calculations for C of G to be done. It may not be pretty but it does the job. If you want a copy email me. Croft At 04:51 12 January 2012, RAS56 wrote: Hagbard Celine;807559 Wrote: If the shop has a digital protractor you could also convert the rise/ run to degrees, put the protractor on the specified part of the tail boom and raise the tail until it reads the correct angle. Arctan(rise/run) = angle in degrees About 2.1 degrees, sloping down towards the tail in this case. Same question, hopefully same answer...could use a little more info. I'm trying to put together a W&B event at our club, we're bringing in outside help from another club with a set of scales and the experience of knowing what to do. WRT positioning the glider at the correct angle, my ship is an ASW-19b. Although my owners manual has a page dedicated to CG info, there's nothing in there about what procedure to use to actually weigh the thing. It's just a page with a CG envelope on it. Now I did find on page 30 of the manual (a page that has general dimensions as well as specs for control deflections) a side view drawing with info presented as the thread starter discussed, mine says 1000 by 45. SO, to do the procedure correctly, construct a small triangle with those dimensions, inflate the main wheel to proper pressure, put a level on the triangle, then raise the tail till I get a level bubble? It would seem to make sense that this is done with wings level laterally as well, correct? Lightly (fingertips) or is a wingstand under a tip ok? THEN, take the weights? Finally, this will be the 4th W&B for this glider. All the ones done previously have had a "form" with a glider drawing on it and appropriate spots to fill in main wheel/tail wheel weights, etc. Where can we obtain "blanks" to fill in our ships for our event? We will have an A&P IA overseeing the process and signing off logbooks. As I said, I'm coordinating, so I'm trying to get all the info/materials each owner will need to have on hand at weigh-in so the event goes smoothly. Thanks much, Rob ASW-19b ZAP Ps-sorry if this double posts... -- RAS56 |
#15
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Croft,
If you could email it to me at: aggies78 at gmail.com That would be much appreciated! Thanks. Rob S. |
#16
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Measurement of CofG
At 04:51 12 January 2012, RAS56 wrote:
Finally, this will be the 4th W&B for this glider. All the ones done previously have had a "form" with a glider drawing on it and appropriate spots to fill in main wheel/tail wheel weights, etc. Where can we obtain "blanks" to fill in our ships for our event? We will have an A&P IA overseeing the process and signing off logbooks. As I said, I'm coordinating, so I'm trying to get all the info/materials each owner will need to have on hand at weigh-in so the event goes smoothly. Thanks much, Rob ASW-19b Try http://www.gliding.co.uk/bgainfo/tec...manual/4-1.pdf which is a good guide to the process |
#17
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Measurement of CofG
Hey, Rob!
ZAP was my second glider. I flew her between April '88 and Nov '91. Blast from the past! "RAS56" wrote in message ... Same question, hopefully same answer...could use a little more info. I'm trying to put together a W&B event at our club, we're bringing in outside help from another club with a set of scales and the experience of knowing what to do. WRT positioning the glider at the correct angle, my ship is an ASW-19b. Although my owners manual has a page dedicated to CG info, there's nothing in there about what procedure to use to actually weigh the thing. It's just a page with a CG envelope on it. Now I did find on page 30 of the manual (a page that has general dimensions as well as specs for control deflections) a side view drawing with info presented as the thread starter discussed, mine says 1000 by 45. SO, to do the procedure correctly, construct a small triangle with those dimensions, inflate the main wheel to proper pressure, put a level on the triangle, then raise the tail till I get a level bubble? It would seem to make sense that this is done with wings level laterally as well, correct? Lightly (fingertips) or is a wingstand under a tip ok? THEN, take the weights? Finally, this will be the 4th W&B for this glider. All the ones done previously have had a "form" with a glider drawing on it and appropriate spots to fill in main wheel/tail wheel weights, etc. Where can we obtain "blanks" to fill in our ships for our event? We will have an A&P IA overseeing the process and signing off logbooks. As I said, I'm coordinating, so I'm trying to get all the info/materials each owner will need to have on hand at weigh-in so the event goes smoothly. Thanks much, Rob ASW-19b ZAP -- RAS56 |
#18
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Measurement of CofG
Some do. The Mini Nimbus has the correct height to raise the tail skid
from the floor. Makes things easier for sure. On Jan 11, 4:29*pm, "Dan Marotta" wrote: Why don't the manufactures publish the height to raise the tail as a difference between the axle center lines above ground? *Then you don't need to cut or calculate. Oh, gee... *That'd be too simple. "Hagbard Celine" wrote in message If the shop has a digital protractor you could also convert the rise/ run to degrees, put the protractor on the specified part of the tail boom and raise the tail until it reads the correct angle. Arctan(rise/run) = angle in degrees About 2.1 degrees, sloping down towards the tail in this case. |
#19
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Measurement of CofG
When I did my Ventus (not a club plane) I did it with flying weight. IE I
started with me, flying gear, water ballast, drinking water, batteries ect. in the plane. Being of sound ballast myself I needed to dump ballast to get to gross weight. I did this with a stop watch and 5 gallon buckets under the dump valves and had the "Weigher" tell me when I got to gross, stop and record both time and gallons dumped, then continued to 9 lbs per sq ft, stop and record, then dumped the rest. This gave me a very accurate amounts in both gallons and time (seconds to dump for any wing loading I may want to fly with. Now I just time the fill time to half ballast and fly After all its a Ventus and won't thermal worth a crap with full load CH Ventus B CH Ventus B "If we are all "just dust in the wind", then I want to be at the top of a Huge Dust Devil!" |
#20
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Measurement of CofG
On Jan 11, 4:29*pm, "Dan Marotta" wrote:
Why don't the manufactures publish the height to raise the tail as a difference between the axle center lines above ground? *Then you don't need to cut or calculate. Oh, gee... *That'd be too simple. One possible reason is that the height is not a constant for any glider that has a compressible pneumatic tyre or a sprung landing gear. Both have deflection that depends on the glider mass. That same deflection would need to be applied to the tail height. It may not be neglible at max gross wt. Speaking of sprung landing gear - in some cases the deflection changes not only the height but also the distance between the tyre/ground contact point and the datum. That applies to modern Schleicher single seaters and probably other gliders. The best plan is to do the weight and ballance as defined by the manufacturer. I also calculated my own pilot arm as I considered the generalities in the manual to be unacceptable. That can be done with a reasonably accurate bathroom scale under the tail as the calculation is independent of weight on the main gear. Andy (GY) |
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