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18m Nationals weight restriction at Seminole



 
 
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  #11  
Old March 9th 18, 09:55 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 4:47:40 PM UTC-5, Dave Nadler wrote:
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!


Dave, unfortunately I am not going to endorse this decision with my participation. To me it is a fairness issue. Have this rule implemented on the west coast and I will not argue on the east coast this rule clearly favours some gliders over others.
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  #12  
Old March 9th 18, 10:20 PM posted to rec.aviation.soaring
MNLou
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Posts: 159
Default 18m Nationals weight restriction at Seminole

Andy -

One option you didn't list is a "dry contest". Just curious as to why that wasn't explored.

Thanks!

Lou
  #13  
Old March 9th 18, 10:31 PM posted to rec.aviation.soaring
Andy Blackburn[_3_]
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Posts: 474
Default 18m Nationals weight restriction at Seminole

On Friday, March 9, 2018 at 4:50:41 PM UTC-5, Andrzej Kobus wrote:
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.


Andrzej,

Your proposed solution is to set the takeoff weight for your glider suitable to meet the takeoff requirement and then put an additional (and unnecessary to the safety goal) weight reduction on other gliders with less wing area. It's not in the spirit or letter of the rules to force other gliders down to an artificially reduced wing loading. If they can take off at a higher wing loading and you can't because your glider is heavier, it's not up to the rules to equalize that any more than it is the job of the rules to equalize it in a situation without a runway limitation.

It did not escape anyone that on any given day the optimal wing loading may be anywhere across a range of possibilities depending on conditions - or that average thermal strength is generally lower in the east than the west. The issue is should we impose an additional wing loading reduction on other gliders with less wing area than the heaviest ones flying even though there is no reason to do it from a takeoff perspective?

I appreciate that you may have the view that the optimal wing loading in Florida is no more than 9 lbs/sf and that suits you and your glider, but there are many other gliders and many other pilots as well. For instance a JS3 would be forced to take off 200 pounds lighter than an ASH-31mi to meet 9 lbs/sf. When faced with the requirement of limiting weight for safety purposes, there's simply no rationale in the rules for imposing additional restrictions beyond what's required for safety.

If you'd like to introduce a proposal that we impose a maximum wing loading in 18M class as a general rule we could certainly survey the pilots and see if there is broad agreement, but it's not in the rules now. These decision need to be made based on a consistent set of principles, not what suits one person or another or one glider or another.

Andy Blackburn
9B
  #14  
Old March 9th 18, 10:37 PM posted to rec.aviation.soaring
Andy Blackburn[_3_]
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Posts: 474
Default 18m Nationals weight restriction at Seminole

On Friday, March 9, 2018 at 5:20:04 PM UTC-5, MNLou wrote:
Andy -

One option you didn't list is a "dry contest". Just curious as to why that wasn't explored.

Thanks!

Lou


Thanks Lou,

I apologize, that did come up and was considered. It created the most disruption of all the options. The goal was to minimize the amount of change from a contest with no weight restriction.

Andy
  #15  
Old March 9th 18, 10:40 PM posted to rec.aviation.soaring
Dave Nadler
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Posts: 1,271
Default 18m Nationals weight restriction at Seminole

On Friday, March 9, 2018 at 5:20:04 PM UTC-5, MNLou wrote:
One option you didn't list is a "dry contest".
Just curious as to why that wasn't explored.


That would be quite unfair to gliders with a low minimum wing-loading...

Of course with my machines I wouldn't know about low wing-loading ;-)
  #16  
Old March 9th 18, 10:42 PM posted to rec.aviation.soaring
Tango Eight
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Posts: 568
Default 18m Nationals weight restriction at Seminole

Andy: AK has a legitimate gripe. At Seminole, he had the expectation of flying at rough parity for reasons he's laid out and that any reasonable E. Coast pilot concurs with. An 1150 gross weight limit gives a significant advantage to the 29s and JS-3s **in this environment** that does not exist otherwise.

AK: I agree with Dave, you should go fly.

Rules Committee should reconsider this.

T8
  #17  
Old March 9th 18, 10:44 PM posted to rec.aviation.soaring
Tom Kelley #711
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Posts: 267
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


For Andy, 9B, the max. weight of the ASG 29 18 Meter is 1322 lbs(600 kg). Then divided by 113 sq. ft. which gives a 11.7 lbs sq. ft. loading. The 12..2 lbs you list is for ASG 29/15 Meter max. wing loading(1202 divided by 99 sq. ft.)

Thanks for your work on this as a safe and fair contest is what we need. Why some may ask why at Seminole? No one else, I was told, was interested in the contest as its an east coast contest this year.

First practice day most few, it was weak, several landouts, but most home. Check OGN network for live tracking.

Best. #711.

  #18  
Old March 9th 18, 10:47 PM posted to rec.aviation.soaring
Andrzej Kobus
external usenet poster
 
Posts: 482
Default 18m Nationals weight restriction at Seminole

On Friday, March 9, 2018 at 5:31:24 PM UTC-5, Andy Blackburn wrote:
On Friday, March 9, 2018 at 4:50:41 PM UTC-5, Andrzej Kobus wrote:
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.


Andrzej,

Your proposed solution is to set the takeoff weight for your glider suitable to meet the takeoff requirement and then put an additional (and unnecessary to the safety goal) weight reduction on other gliders with less wing area. It's not in the spirit or letter of the rules to force other gliders down to an artificially reduced wing loading. If they can take off at a higher wing loading and you can't because your glider is heavier, it's not up to the rules to equalize that any more than it is the job of the rules to equalize it in a situation without a runway limitation.

It did not escape anyone that on any given day the optimal wing loading may be anywhere across a range of possibilities depending on conditions - or that average thermal strength is generally lower in the east than the west.. The issue is should we impose an additional wing loading reduction on other gliders with less wing area than the heaviest ones flying even though there is no reason to do it from a takeoff perspective?

I appreciate that you may have the view that the optimal wing loading in Florida is no more than 9 lbs/sf and that suits you and your glider, but there are many other gliders and many other pilots as well. For instance a JS3 would be forced to take off 200 pounds lighter than an ASH-31mi to meet 9 lbs/sf. When faced with the requirement of limiting weight for safety purposes, there's simply no rationale in the rules for imposing additional restrictions beyond what's required for safety.

If you'd like to introduce a proposal that we impose a maximum wing loading in 18M class as a general rule we could certainly survey the pilots and see if there is broad agreement, but it's not in the rules now. These decision need to be made based on a consistent set of principles, not what suits one person or another or one glider or another.

Andy Blackburn
9B


Andy, so far you failed to understand the other side of the argument. You are saying "It's not in the spirit or letter of the rules to force other gliders down to an artificially reduced wing loading." I am asking, is it in the spirit of the rules to force my glider to an artificially low wing loading? I hope not, but that is what you are doing. If you can force me to such unreasonably low wing loading why can't your force the other gliders.

You are trying to preserve the perceived advantage that ASG-29 would have due to its ability to load to around 12 lb/sq foot. The problem with that is that at the location of this contest this advantage does not exist, so you in fact legislated it.

I am very surprised that this decision was made without polling pilots or any discussion. The rules only talk about dry contest or FAI limit. I did not think this option even existed.

Andrzej
One less pilot flying contests




  #19  
Old March 9th 18, 10:50 PM posted to rec.aviation.soaring
Dave Nadler
external usenet poster
 
Posts: 1,271
Default 18m Nationals weight restriction at Seminole

On Friday, March 9, 2018 at 5:42:37 PM UTC-5, Tango Eight wrote:
An 1150 gross weight limit gives a significant advantage
to the 29s and JS-3s **in this environment** that does not exist otherwise.


Only if we have pretty strong weather. Let's hope, but...
I'm not going to complain too much about being limited to 9.5!
  #20  
Old March 9th 18, 11:04 PM posted to rec.aviation.soaring
Andy Blackburn[_3_]
external usenet poster
 
Posts: 474
Default 18m Nationals weight restriction at Seminole

On Friday, March 9, 2018 at 5:44:21 PM UTC-5, Tom Kelley #711 wrote:
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


For Andy, 9B, the max. weight of the ASG 29 18 Meter is 1322 lbs(600 kg). Then divided by 113 sq. ft. which gives a 11.7 lbs sq. ft. loading. The 12.2 lbs you list is for ASG 29/15 Meter max. wing loading(1202 divided by 99 sq. ft.)

Thanks for your work on this as a safe and fair contest is what we need. Why some may ask why at Seminole? No one else, I was told, was interested in the contest as its an east coast contest this year.

First practice day most few, it was weak, several landouts, but most home.. Check OGN network for live tracking.

Best. #711.


Thanks Tom - I grabbed the 15M weight.

Andy
 




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