A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Soaring
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

The Yellow Triangle



 
 
Thread Tools Display Modes
  #21  
Old February 18th 21, 02:48 PM posted to rec.aviation.soaring
John Galloway[_2_]
external usenet poster
 
Posts: 45
Default The Yellow Triangle

On Thursday, 18 February 2021 at 13:11:35 UTC, Eric Greenwell wrote:
Nicholas Kennedy wrote on 2/16/2021 4:56 PM:
On many German gliders on the ASI is a yellow triangle.
This Yelloe Triangle on my ASw 20 and my LS3a is the factory recommended approach airspeed. This speed is 49 knots.
This has bothered me for a long time now, I think the factory did alot of pilots a disservice by putting this, to me anyway, very low number on there.
On both the above gliders, the max speed, normal landing flap flaps down, is 86 knots.
About 15 years ago my Gold Seal flight instructor Bob Faris, CX,indicated to me in his LS3 he planned on a much higher speed in the pattern, like 70-75 knots depending on conditions. I followed suit ever since.

Since so many gliders have 49 knots for the Yellow Triangle, I think this might be a regulatory
requirement, not a choice by the glider manufacturer. Perhaps gliders are required to have an
approach speed no higher than 49 knots at a certain weight with the regulation required control
authority.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1


In the EASA CS22 specification for ASI markings it includes "a yellow marking (triangle) for the lowest approach speed (at maximum weight without water ballast) *recommended by the manufacturer*". (My stars). As far as I can see there is neither a set value nor a formula for deriving it from e.g. stall speeds
Ads
  #22  
Old February 18th 21, 04:13 PM posted to rec.aviation.soaring
andy l
external usenet poster
 
Posts: 56
Default The Yellow Triangle

On Thursday, 18 February 2021 at 14:48:55 UTC, wrote:
On Thursday, 18 February 2021 at 13:11:35 UTC, Eric Greenwell wrote:
Nicholas Kennedy wrote on 2/16/2021 4:56 PM:
On many German gliders on the ASI is a yellow triangle.
This Yelloe Triangle on my ASw 20 and my LS3a is the factory recommended approach airspeed. This speed is 49 knots.
This has bothered me for a long time now, I think the factory did alot of pilots a disservice by putting this, to me anyway, very low number on there.
On both the above gliders, the max speed, normal landing flap flaps down, is 86 knots.
About 15 years ago my Gold Seal flight instructor Bob Faris, CX,indicated to me in his LS3 he planned on a much higher speed in the pattern, like 70-75 knots depending on conditions. I followed suit ever since.

Since so many gliders have 49 knots for the Yellow Triangle, I think this might be a regulatory
requirement, not a choice by the glider manufacturer. Perhaps gliders are required to have an
approach speed no higher than 49 knots at a certain weight with the regulation required control
authority.
--
Eric Greenwell - Washington State, USA
https://sites.google.com/site/motorg...ad-the-guide-1

In the EASA CS22 specification for ASI markings it includes "a yellow marking (triangle) for the lowest approach speed (at maximum weight without water ballast) *recommended by the manufacturer*". (My stars). As far as I can see there is neither a set value nor a formula for deriving it from e.g. stall speeds


There's probably some approximation or rounding

49 and 54 knots might sound like precision to us, but these are 90 and 100 km/h. 86 kts is 160 km/h


  #23  
Old February 18th 21, 10:01 PM posted to rec.aviation.soaring
Dan Daly[_2_]
external usenet poster
 
Posts: 704
Default The Yellow Triangle

My D2B says 54 kts. The standard does not fix a given speed.
IN


My SZD-55 says 56.7 kts/105 kph.
CS 22.1545 Air-speed indicator (See AMC 22.1545)
Each air-speed indicator must show the following markings:
.... some deleted ....
(e) a yellow marking (triangle) for the lowest approach speed (at maximum weight without water ballast) recommended by the manufacturer;
2D
  #24  
Old February 18th 21, 10:36 PM posted to rec.aviation.soaring
Charlie M. (UH & 002 owner/pilot)
external usenet poster
 
Posts: 1,380
Default The Yellow Triangle

On Thursday, February 18, 2021 at 7:48:45 AM UTC-5, wrote:
There is margin at the yellow triangle.

ASW-20B, landing flaps + full spoilers on final, spoilers held open all the way to wheel stopped.

Touch down is tail first, landing roll 200', disk brake on hard but not rubbing nose in the dirt.

https://www.youtube.com/watch?v=oBexl9GfKK0

T8

My feeling/training others....what does it feel like, what does it look like, what does it sound like....make it all seem correct...don't break the aircraft....
  #25  
Old February 18th 21, 11:32 PM posted to rec.aviation.soaring
Nicholas Kennedy
external usenet poster
 
Posts: 59
Default The Yellow Triangle

This is the problem I'm referring too:

https://www.youtube.com/watch?v=use6PnxjO7s

Nick
T

  #26  
Old February 19th 21, 12:41 AM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 225
Default The Yellow Triangle

On Thursday, February 18, 2021 at 7:48:45 AM UTC-5, wrote:
There is margin at the yellow triangle.

ASW-20B, landing flaps + full spoilers on final, spoilers held open all the way to wheel stopped.

Touch down is tail first, landing roll 200', disk brake on hard but not rubbing nose in the dirt.

https://www.youtube.com/watch?v=oBexl9GfKK0

T8

There is plenty of margin, try putting a cover over your airspeed indicator for the entire flight, actually it will be in your best interest to see exactly how your ship flies. E9 did this to me back in the day and it taught me a thing or two. Number one is that fly by the seat of your pants, number two prepare yourself for the off field landing. We did this often and it was one of the best learning experiences that I ever had.
  #27  
Old February 19th 21, 01:12 AM posted to rec.aviation.soaring
Tango Eight
external usenet poster
 
Posts: 957
Default The Yellow Triangle

On Thursday, February 18, 2021 at 6:32:19 PM UTC-5, wrote:
This is the problem I'm referring too:

https://www.youtube.com/watch?v=use6PnxjO7s

Nick
T


That sort of accident has nothing to do with speed on final approach.

T8

  #28  
Old February 19th 21, 04:38 PM posted to rec.aviation.soaring
bgrly[_2_]
external usenet poster
 
Posts: 2
Default The Yellow Triangle

On Thursday, February 18, 2021 at 7:12:31 PM UTC-6, wrote:
On Thursday, February 18, 2021 at 6:32:19 PM UTC-5, wrote:
This is the problem I'm referring too:

https://www.youtube.com/watch?v=use6PnxjO7s

Nick
T

That sort of accident has nothing to do with speed on final approach.

T8


Discussions at my club and at a FIRC prompted my research and writing a piece on my personal website. The link is below. I suspect or expect a few comments, as undoubtedly somebody will think I"m all wet. Mention of the huey is because that's what I know.

http://www.unofficialuseonly.us/gelbe.html

Brent, 7A ,
  #29  
Old February 21st 21, 12:55 AM posted to rec.aviation.soaring
NG[_2_]
external usenet poster
 
Posts: 31
Default The Yellow Triangle

I suggest avoiding blanket statements like assertions that the yellow triangle is ALWAYS based on max unballasted weight. On my 1980 Ventus A, the yellow triangle is required by the flight manual to be at 62 knots based on max allowable weight (with full ballast) at 525 kg / 1157 lbs and landing flaps down, airbrakes retracted. Design rules have undoubtedly changed since then, but the POH is always the final authority.
  #30  
Old February 21st 21, 01:13 AM posted to rec.aviation.soaring
India November[_2_]
external usenet poster
 
Posts: 30
Default The Yellow Triangle

On Friday, February 19, 2021 at 11:38:02 AM UTC-5, bgrly wrote:
On Thursday, February 18, 2021 at 7:12:31 PM UTC-6, wrote:
On Thursday, February 18, 2021 at 6:32:19 PM UTC-5, wrote:
This is the problem I'm referring too:

https://www.youtube.com/watch?v=use6PnxjO7s

Nick
T

That sort of accident has nothing to do with speed on final approach.

T8

Discussions at my club and at a FIRC prompted my research and writing a piece on my personal website. The link is below. I suspect or expect a few comments, as undoubtedly somebody will think I"m all wet. Mention of the huey is because that's what I know.

http://www.unofficialuseonly.us/gelbe.html

Brent, 7A ,


I have understood (though I can't give you a reference) the YT as marking the minimum recommended approach speed needed to complete the landing flare at max mass without water ballast in calm air. Modern gliders have a high rate of descent with airbrakes fully extended and gear down. The D2b flight manual status that the L/D in this configuration is approximately 5.8:1, which translates to a sink rate of roughly -10kts. In this condition you need enough airspeed to arrest the descent and flare. If the approach is too slow, the glider will mush and land heavily. The YT doesn't say anything per se about airspeed margin for wind gradient and gusts.

A variety of approaches can be found in the literature on the subject of approach airspeed in windy conditions, e.g.:

1.3 Vso plus the full wind speed (Soaring Association of Canada Student handbook p61) http://www.sac.ca/index.php/en/docum...011-optim/file
1.5 Vso plus half the gust speed if not otherwise specified in the POH (FAA glider manual pp 7-23 and 7-25) https://www.faa.gov/regulations_poli...h-8083-13a.pdf
1.5 Vso plus half the wind plus all the gust (Soaring Safety Foundation). https://www.soaringsafety.org/public...6-airspeed.pdf

They all give the same general advice, that is fly higher airspeed in windy and gusty conditions. I don't claim to know which exact formula which is best.

Ian IN




 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Tales Of The Bloody Triangle [email protected] Soaring 36 March 12th 21 12:25 AM
OLC FAI triangle geometry different than FAI [email protected] Soaring 1 September 5th 15 12:41 PM
200km/hr 100km triangle Tony[_5_] Soaring 2 January 14th 15 04:05 PM
500 km Triangle at 306 km/hr in Argentina Paul Remde Soaring 36 January 3rd 07 08:48 PM
FAI triangle in SEE YOU Paul Feltz Soaring 2 July 7th 04 07:46 AM


All times are GMT +1. The time now is 03:33 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Copyright 2004-2021 AviationBanter.
The comments are property of their posters.