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18m Nationals weight restriction at Seminole



 
 
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  #1  
Old March 9th 18, 02:06 AM posted to rec.aviation.soaring
Andrzej Kobus
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Default 18m Nationals weight restriction at Seminole

I just found out that due to a short runway at Seminole a decision was made to restrict the weight of each glider to 1150 lb. Supposedly the decision was made after consultation with pilots, not sure with whom. I would love to know who thought that it was a great idea. This leaves gliders with higher wing area (mostly self launchers) at disadvantage. E.g. ASH-31 Mi would have to fly with lower wing loading by 1.1 lb/sq foot comparing to ASG-29. It puzzles me greatly who made this decision and why. A much more reasonable solution would have been to limit the wing loading for each glider. That is how it is done in a Grand Prix event. In my opinion it is the only fair way to limit weight at such a low, for 18 m class, weight range. I don't think an organizer should be able to limit weight effectively creating a different class. I decided to withdraw from the competition. It is one more reason contest participation is dropping.
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  #2  
Old March 9th 18, 03:19 PM posted to rec.aviation.soaring
Kevin Christner
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Default 18m Nationals weight restriction at Seminole

Wilbur Wright personally approved of this limit. He and asw20pilot are very positive on Seminole Lake.

On Thursday, March 8, 2018 at 9:06:25 PM UTC-5, Andrzej Kobus wrote:
I just found out that due to a short runway at Seminole a decision was made to restrict the weight of each glider to 1150 lb. Supposedly the decision was made after consultation with pilots, not sure with whom. I would love to know who thought that it was a great idea. This leaves gliders with higher wing area (mostly self launchers) at disadvantage. E.g. ASH-31 Mi would have to fly with lower wing loading by 1.1 lb/sq foot comparing to ASG-29. It puzzles me greatly who made this decision and why. A much more reasonable solution would have been to limit the wing loading for each glider. That is how it is done in a Grand Prix event. In my opinion it is the only fair way to limit weight at such a low, for 18 m class, weight range. I don't think an organizer should be able to limit weight effectively creating a different class. I decided to withdraw from the competition. It is one more reason contest participation is dropping.


  #3  
Old March 9th 18, 04:05 PM posted to rec.aviation.soaring
Andy Blackburn[_3_]
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Default 18m Nationals weight restriction at Seminole

On Thursday, March 8, 2018 at 9:06:25 PM UTC-5, Andrzej Kobus wrote:
I just found out that due to a short runway at Seminole a decision was made to restrict the weight of each glider to 1150 lb. Supposedly the decision was made after consultation with pilots, not sure with whom. I would love to know who thought that it was a great idea. This leaves gliders with higher wing area (mostly self launchers) at disadvantage. E.g. ASH-31 Mi would have to fly with lower wing loading by 1.1 lb/sq foot comparing to ASG-29. It puzzles me greatly who made this decision and why. A much more reasonable solution would have been to limit the wing loading for each glider. That is how it is done in a Grand Prix event. In my opinion it is the only fair way to limit weight at such a low, for 18 m class, weight range. I don't think an organizer should be able to limit weight effectively creating a different class. I decided to withdraw from the competition. It is one more reason contest participation is dropping.


There are two reasons for this approach:

1) Takeoff distance is driven primarily by takeoff weight and only secondarily by wing loading. A full aerodynamic factor analysis of takeoff performance was done to confirm this fact. A wing loading limit would have allowed gliders with larger wing area to take off at a heavier weight than smaller wing area gliders, compromising the takeoff safety goal.

2) FAI and Grand Prix rules are different. Grand Prix attempts to handicap gliders, FAA decidedly does not. Some glider designs are optimized for running at high wing loading and give up some climbing ability and others are the opposite. Pilots choose to fly different gliders in part because they are making choices for one design strategy over others. FAI rules specifically allow for different wing loading design strategies. The maximum wing loading of the various 18M gliders in this contest range from 10.4 lbs to 12.3 lbs. Setting a wing loading limit would have eliminated these design differences on the run while forcing smaller wing area designs to fly with a climb tradeoff. A wing loading limit would advantage large wing area gliders and disadvantage low wing area gliders as compared to flying within the normal limits of the 18M FAI class.

The minimum intervention in the relative competitiveness of gliders to achieve the takeoff distance goal for this airport is therefore takeoff weight. The approach you suggest would have conferred an advantage to the specific glider you are flying that is not part of the philosophy or rules of the FAI 18M class.

Hope that helps.

Andy Blackburn
9B
For the Rules Committee
  #4  
Old March 9th 18, 04:35 PM posted to rec.aviation.soaring
Andrzej Kobus
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Default 18m Nationals weight restriction at Seminole

On Friday, March 9, 2018 at 11:05:04 AM UTC-5, Andy Blackburn wrote:
"The approach you suggest would have conferred an advantage to the specific glider you are flying that is not part of the philosophy or rules of the FAI 18M class"

Andy, I can't believe what you wrote, did you read it before you sent it? Did you write it in the name of the Rules committee or is it your own opinion?

What advantage would I get, if I fly at the same wing loading as an ASG-29?
You must be kidding the 18M class weight restriction is 1320 lb. By limiting the weight you are handicapping me more than you are handicapping an ASG-29. On the east coast the optimum wing loading is around 10 lb/sq foot. You let the ASG-29 fly with that wing loading while handicapping me to 9 lb/sq foot. If not for the restriction I would be able to fly at the optimal wing loading. How is that fair? It seems to me the competition should never have been allowed to be held at an airport that can not handle the requirements of the 18 m class. Hopefully this is the last time Seminole is awarded a FAI class competition.
  #5  
Old March 9th 18, 04:59 PM posted to rec.aviation.soaring
Ron Gleason
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Posts: 413
Default 18m Nationals weight restriction at Seminole

On Friday, 9 March 2018 09:35:06 UTC-7, Andrzej Kobus wrote:
On Friday, March 9, 2018 at 11:05:04 AM UTC-5, Andy Blackburn wrote:
"The approach you suggest would have conferred an advantage to the specific glider you are flying that is not part of the philosophy or rules of the FAI 18M class"

Andy, I can't believe what you wrote, did you read it before you sent it? Did you write it in the name of the Rules committee or is it your own opinion?

What advantage would I get, if I fly at the same wing loading as an ASG-29?
You must be kidding the 18M class weight restriction is 1320 lb. By limiting the weight you are handicapping me more than you are handicapping an ASG-29. On the east coast the optimum wing loading is around 10 lb/sq foot. You let the ASG-29 fly with that wing loading while handicapping me to 9 lb/sq foot. If not for the restriction I would be able to fly at the optimal wing loading. How is that fair? It seems to me the competition should never have been allowed to be held at an airport that can not handle the requirements of the 18 m class. Hopefully this is the last time Seminole is awarded a FAI class competition.


Andrej, while I understand your passion and desire to 'level the playing field' IMHO safety has to be number one priority. A 10/lb per sq ft wing loading does you no good if you are on the ground in a field or the swamp around Seminole because the tow plane had to release you for their own safety.

In 2016 at Nephi we intentionally launched the open class last each day for safety. Even with 5,000 feet plus of usable runway getting 800 Kg open class gliders in the air safely was on the margin even with the most powerful tow planes. We took heat for it but it is just the right thing to do. Yes it caused shorter tasks some days but we had 100% safety record for launches and that was our goal and priority.

Your statement 'It seems to me the competition should never have been allowed to be held at an airport that can not handle the requirements of the 18 m class. Hopefully this is the last time Seminole is awarded a FAI class competition.' is short sighted and selfish. The number of locations that are able and willing to host contests is shrinking across the US. IMO compromises, like a weight limit, are acceptable for some locations.

With that said, I do believe that the SSA contest committee and site selection committee should have caught this sooner (folks that volunteer on these committees have and do fly out of Seminole) and had this information available to interested pilots at time of sanctioning and/or registration.

Ron Gleason
  #6  
Old March 9th 18, 05:08 PM posted to rec.aviation.soaring
[email protected]
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Posts: 38
Default 18m Nationals weight restriction at Seminole

If 1150lb is what is decided as the max safe tow weight, then you could set the wing loading limit to highest entered wing area glider / 1150lb.

Handicap on wingloading, advantage the JS1. Handicap on weight, advantage the ASG29.

¯\_(ツ)_/¯

On Friday, March 9, 2018 at 8:59:44 AM UTC-8, Ron Gleason wrote:
On Friday, 9 March 2018 09:35:06 UTC-7, Andrzej Kobus wrote:
On Friday, March 9, 2018 at 11:05:04 AM UTC-5, Andy Blackburn wrote:
"The approach you suggest would have conferred an advantage to the specific glider you are flying that is not part of the philosophy or rules of the FAI 18M class"

Andy, I can't believe what you wrote, did you read it before you sent it? Did you write it in the name of the Rules committee or is it your own opinion?

What advantage would I get, if I fly at the same wing loading as an ASG-29?
You must be kidding the 18M class weight restriction is 1320 lb. By limiting the weight you are handicapping me more than you are handicapping an ASG-29. On the east coast the optimum wing loading is around 10 lb/sq foot. You let the ASG-29 fly with that wing loading while handicapping me to 9 lb/sq foot. If not for the restriction I would be able to fly at the optimal wing loading. How is that fair? It seems to me the competition should never have been allowed to be held at an airport that can not handle the requirements of the 18 m class. Hopefully this is the last time Seminole is awarded a FAI class competition.


Andrej, while I understand your passion and desire to 'level the playing field' IMHO safety has to be number one priority. A 10/lb per sq ft wing loading does you no good if you are on the ground in a field or the swamp around Seminole because the tow plane had to release you for their own safety..

In 2016 at Nephi we intentionally launched the open class last each day for safety. Even with 5,000 feet plus of usable runway getting 800 Kg open class gliders in the air safely was on the margin even with the most powerful tow planes. We took heat for it but it is just the right thing to do. Yes it caused shorter tasks some days but we had 100% safety record for launches and that was our goal and priority.

Your statement 'It seems to me the competition should never have been allowed to be held at an airport that can not handle the requirements of the 18 m class. Hopefully this is the last time Seminole is awarded a FAI class competition.' is short sighted and selfish. The number of locations that are able and willing to host contests is shrinking across the US. IMO compromises, like a weight limit, are acceptable for some locations.

With that said, I do believe that the SSA contest committee and site selection committee should have caught this sooner (folks that volunteer on these committees have and do fly out of Seminole) and had this information available to interested pilots at time of sanctioning and/or registration.

Ron Gleason


  #7  
Old March 9th 18, 05:27 PM posted to rec.aviation.soaring
Andrzej Kobus
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Posts: 482
Default 18m Nationals weight restriction at Seminole

On Friday, March 9, 2018 at 12:08:31 PM UTC-5, wrote:
If 1150lb is what is decided as the max safe tow weight, then you could set the wing loading limit to highest entered wing area glider / 1150lb.

Handicap on wingloading, advantage the JS1. Handicap on weight, advantage the ASG29.

¯\_(ツ)_/¯


Absolutely, that is how they should have done this to be fair.
  #8  
Old March 9th 18, 08:27 PM posted to rec.aviation.soaring
Andy Blackburn[_3_]
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Posts: 473
Default 18m Nationals weight restriction at Seminole

On Friday, March 9, 2018 at 11:35:06 AM UTC-5, Andrzej Kobus wrote:
On Friday, March 9, 2018 at 11:05:04 AM UTC-5, Andy Blackburn wrote:
"The approach you suggest would have conferred an advantage to the specific glider you are flying that is not part of the philosophy or rules of the FAI 18M class"

Andy, I can't believe what you wrote, did you read it before you sent it? Did you write it in the name of the Rules committee or is it your own opinion?

What advantage would I get, if I fly at the same wing loading as an ASG-29?
You must be kidding the 18M class weight restriction is 1320 lb. By limiting the weight you are handicapping me more than you are handicapping an ASG-29. On the east coast the optimum wing loading is around 10 lb/sq foot. You let the ASG-29 fly with that wing loading while handicapping me to 9 lb/sq foot. If not for the restriction I would be able to fly at the optimal wing loading. How is that fair? It seems to me the competition should never have been allowed to be held at an airport that can not handle the requirements of the 18 m class. Hopefully this is the last time Seminole is awarded a FAI class competition.


Hi Andrzej,

Thanks for your thoughts.

This was exhaustively analyzed and debated over a period of weeks, not a knee-jerk decision. I did supporting analysis, but the waiver request was from the contest organizers and approved by the SSA Board. Feel free to blame me as I support the approach taken and I meant exactly what I said above.

There were three approachers considered:

1) Fixed wing loading
2) Fixed MTOW
3) Fixed % reduction in MTOW from max certified

The criteria were basically twofold:
1) Address as directly as possible the concerns related to takeoff distance over an obstacle
2) Minimize any alteration to the existing relative performance differences across glider types - that is, minimize handicapping by glider type.

The maximum certified wing loading of gliders flying in 18M Class under the rules a

HpH 304S - 10.4 lbs/sf
ASH-31Mi - 10.8 lbs/sf
JS1C-18 - 11.0 lbs/sf
Ventus 3 - 11.3 lbs/sf
ASG-29 - 12.3 lbs/sf
JS3 - 12.4 lbs/sf (none signed up as of this writing)

Without any weight restrictions, the ASH-31 and JS1 would fly at close to 1..5 lbs lower maximum loading that the ASG-29 and JS3 and about half a pound lighter than the Ventus 3. A percent weight limit preserves the proportionate max wing loading differences but reduces the absolute differences by the amount of the % reduction. Setting a weight limit closes that gap to closer to 1 lb/sf and a wing loading limit totally eliminates it - effectively handicapping the higher wing loading gliders. To answer your specific question, handicapping most of the gliders other than yours gives you a benefit that you wouldn't otherwise have. I can see why you would prefer this as it would help you compete under strong conditions in particular.

However, there is nothing in the letter or the spirit of the rules governing 18M class (unlike Sports Class or SGP racing) that says we should handicap the performance of gliders - quite the opposite. People in non-handicapped classes purchase gliders for the specific design and performance tradeoffs of that design and have a right to expect that those choices wouldn't be deliberately diluted through changes in the rules. Motor gliders present some unique challenges because the designs represent an inherent tradeoff in wing loading range to accommodate a motor. That's the choice you make when you buy a motorglider - there are some benefits and some tradeoffs.

The other point is a wing loading limit doesn't purely address the takeoff distance challenge. It allows gliders with more wing area to fly at a higher MTOW, making them less safe in terms of takeoff distance due to higher rolling friction on soft ground, slower acceleration under the same thrust, etc. I can take you through the calculations if you like. Restricting takeoff weight is the clearly preferred safety option - it most directly addresses the takeoff distance challenge and does a decent job not changing the competitive capability differences across gliders (actually a % MTOW reduction does slightly better, but does less well on simply addressing the takeoff distance requirement).

I can see why you would have preferred a wing loading limit as it would have benefitted you by reducing the wing loading gap you'd otherwise have faced versus other gliders, but it's not the job of the Rules Committee (or the organizers or the SSA Board) to change that differential for you - particularly if it does a less good job at addressing the primary safety objective..

These issues are not simple to address as there are many moving parts. We attempt to maintain a safe and fair competitive environment consistent with the letter and spirit of the rules, but clearly different alternatives to addressing specific challenges will affect different gliders and pilots differently. Our attempt here is to minimize the changes in the competitive differences between gliders. I'm very comfortable this does the best job of all the alternatives, none of which is 100% perfect. The perfect solution is a longer runway, but that wasn't a realistic alternative.

Andy
  #9  
Old March 9th 18, 09:47 PM posted to rec.aviation.soaring
Dave Nadler
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Default 18m Nationals weight restriction at Seminole

First, make no mistake:
Higher WEIGHT gliders at this site are a real problem.
In addition to length issue, the runway is soft sandy grass.
Gliders with high weights and sometimes smaller tire footprint, well...

Grand Prix rules say equalize all wing loading, based on the highest
minimum wing-loading. For Florida Grand Prix that's me at 9.5 lb/ft2.

I suggested we do the same for 18m nationals; this was not the decision taken.
In any case Florida weather is VERY unlikely to reward higher wing-loadings!
This is not Hobbs!

Stop fussing and come on down Andrzej!
  #10  
Old March 9th 18, 09:50 PM posted to rec.aviation.soaring
Andrzej Kobus
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Posts: 482
Default 18m Nationals weight restriction at Seminole

On Friday, March 9, 2018 at 3:27:50 PM UTC-5, Andy Blackburn wrote:
On Friday, March 9, 2018 at 11:35:06 AM UTC-5, Andrzej Kobus wrote:
On Friday, March 9, 2018 at 11:05:04 AM UTC-5, Andy Blackburn wrote:
"The approach you suggest would have conferred an advantage to the specific glider you are flying that is not part of the philosophy or rules of the FAI 18M class"

Andy, I can't believe what you wrote, did you read it before you sent it? Did you write it in the name of the Rules committee or is it your own opinion?

What advantage would I get, if I fly at the same wing loading as an ASG-29?
You must be kidding the 18M class weight restriction is 1320 lb. By limiting the weight you are handicapping me more than you are handicapping an ASG-29. On the east coast the optimum wing loading is around 10 lb/sq foot. You let the ASG-29 fly with that wing loading while handicapping me to 9 lb/sq foot. If not for the restriction I would be able to fly at the optimal wing loading. How is that fair? It seems to me the competition should never have been allowed to be held at an airport that can not handle the requirements of the 18 m class. Hopefully this is the last time Seminole is awarded a FAI class competition.


Hi Andrzej,

Thanks for your thoughts.

This was exhaustively analyzed and debated over a period of weeks, not a knee-jerk decision. I did supporting analysis, but the waiver request was from the contest organizers and approved by the SSA Board. Feel free to blame me as I support the approach taken and I meant exactly what I said above.

There were three approachers considered:

1) Fixed wing loading
2) Fixed MTOW
3) Fixed % reduction in MTOW from max certified

The criteria were basically twofold:
1) Address as directly as possible the concerns related to takeoff distance over an obstacle
2) Minimize any alteration to the existing relative performance differences across glider types - that is, minimize handicapping by glider type.

The maximum certified wing loading of gliders flying in 18M Class under the rules a

HpH 304S - 10.4 lbs/sf
ASH-31Mi - 10.8 lbs/sf
JS1C-18 - 11.0 lbs/sf
Ventus 3 - 11.3 lbs/sf
ASG-29 - 12.3 lbs/sf
JS3 - 12.4 lbs/sf (none signed up as of this writing)

Without any weight restrictions, the ASH-31 and JS1 would fly at close to 1.5 lbs lower maximum loading that the ASG-29 and JS3 and about half a pound lighter than the Ventus 3. A percent weight limit preserves the proportionate max wing loading differences but reduces the absolute differences by the amount of the % reduction. Setting a weight limit closes that gap to closer to 1 lb/sf and a wing loading limit totally eliminates it - effectively handicapping the higher wing loading gliders. To answer your specific question, handicapping most of the gliders other than yours gives you a benefit that you wouldn't otherwise have. I can see why you would prefer this as it would help you compete under strong conditions in particular.

However, there is nothing in the letter or the spirit of the rules governing 18M class (unlike Sports Class or SGP racing) that says we should handicap the performance of gliders - quite the opposite. People in non-handicapped classes purchase gliders for the specific design and performance tradeoffs of that design and have a right to expect that those choices wouldn't be deliberately diluted through changes in the rules. Motor gliders present some unique challenges because the designs represent an inherent tradeoff in wing loading range to accommodate a motor. That's the choice you make when you buy a motorglider - there are some benefits and some tradeoffs.

The other point is a wing loading limit doesn't purely address the takeoff distance challenge. It allows gliders with more wing area to fly at a higher MTOW, making them less safe in terms of takeoff distance due to higher rolling friction on soft ground, slower acceleration under the same thrust, etc. I can take you through the calculations if you like. Restricting takeoff weight is the clearly preferred safety option - it most directly addresses the takeoff distance challenge and does a decent job not changing the competitive capability differences across gliders (actually a % MTOW reduction does slightly better, but does less well on simply addressing the takeoff distance requirement).

I can see why you would have preferred a wing loading limit as it would have benefitted you by reducing the wing loading gap you'd otherwise have faced versus other gliders, but it's not the job of the Rules Committee (or the organizers or the SSA Board) to change that differential for you - particularly if it does a less good job at addressing the primary safety objective.

These issues are not simple to address as there are many moving parts. We attempt to maintain a safe and fair competitive environment consistent with the letter and spirit of the rules, but clearly different alternatives to addressing specific challenges will affect different gliders and pilots differently. Our attempt here is to minimize the changes in the competitive differences between gliders. I'm very comfortable this does the best job of all the alternatives, none of which is 100% perfect. The perfect solution is a longer runway, but that wasn't a realistic alternative.

Andy


Andy, your reasoning is completely flawed because on the east coast no one flies with wing loading of 12. You so called solution allows some glider to fly at optimum wing loading for the east coast while handicapping higher wing area gliders. I hope you can understand that. If the contest was held in Uvalde your reasoning would have been justified but not at the location the contest is going to be held. I hope you can admit this.

The other point is a wing loading limit doesn't purely address the takeoff distance challenge. It allows gliders with more wing area to fly at a higher MTOW, making them less safe in terms of takeoff distance due to higher rolling friction on soft ground, slower acceleration under the same thrust, etc. I can take you through the calculations if you like.


Again, you could take the weight 1150 divide by the highest wing area glider and establish weight for each of the 4 or 5 types that would never exceed 1150.

I can see why you would have preferred a wing loading limit as it would have benefitted you by reducing the wing loading gap you'd otherwise have faced versus other gliders


Wrong again! I was not disadvantaged on the east coast because I could not use a higher wing loading on the east coast anyway. Once again no one flies on the east coast with wing loading of 12. Your west coast 18,000 cloud bases experience with wide thermals does not translate well to making rules on the east coast.




 




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