That TLAR doesn't look right

As with most things, there are good reasons for the various techniques used in different environments. In the case of the Naval 180 degree turn to final, you must understand the environment the pilots are in.

They are landing on a boat in the middle of the ocean. There are no external references other than the boat. The boat is intentionally headed directly into the wind.

It is important to keep the only visual reference - the boat - in view as you fly the 'pattern.'

Thus the 180 degree turn method.

When landing in farmer Jones farm field, you will have lots of visual clues to use. To make the best use of these clues a disciplined rectangular flight path is an extremely effective method.

For those of you who are unfamiliar with the TLAR landing technique, and are motivated to fly safe, please read the latest edition of the "Glider Flight Training Manual." Available from the SSA or www.eglider.org

Tom Knauff

On Sunday, July 12, 2015 at 8:08:41 AM UTC-7, wrote:
A 180 turn can definitely be performed within 600 feet, but then it has to be done quickly, with a good bank angle, and there is little room for adjustments in elevation. A safe 180 turn type of approach (naval aviator) requires (I think) bank angles that are less than 45 to have the room and time to adjust the rate of descent. In some way it is like having a curved base leg. But you may not do it safely if you are too close.
Please Dan correct me on this, I am not used to do the naval pattern.


Look at the landing pattern in some IGC files on OLC. I don't think you will find many that use a 45 degree angle.

Just for curiosity, I looked at the recent landings at Hobbs of one of the competitors. When he passed the touchdown spot on downwind on July 1, he was roughly 450' above it and 1900' away. This is a ratio of 1:4, not 1:1. The next day his numbers were roughly 700' and 2200', for a ratio of 1:3.

I doubt if anyone can find many IGC files with numbers of 600' and 600'.

OK, I think we have (at least) two different ideas being discussed here, attached to the 45 degree value.

If you look at the article (which I have) one 45 degree reference is to the angle from the base-turn corner looking back to the touch down point. This is a common reference for almost any rectangular pattern described in a myriad of training manuals. It works pretty well for locating the base turn position, provided that enough altitude remains to complete the pattern.

There is the second reference to 45 degrees, which places the glider above the touch down point at the same distance laterally. This is the point (pun intended) where I think we have a few differences of opinion, mainly due to differences in altitude on the downwind. A lower performance (also slower) glider can easily be at 600' lateral displacement and have time and altitude to make corrections on the base leg due to the slower speed.

A faster, higher L/D glider needs a lot more distance/time to dissipate energy and being 600' laterally abeam the touch down would create a significant challenge, both with the turns required to intercept final and the 45 degree base base turn reference.

The article covers the extended downwind as a function of glider performance and clearly explains the need for adjustment.

Having said all that, at our field both a higher and wider pattern is typically flown and I believe the reference angle abeam the touchdown point is often closer to the 30 degrees noted by others.

MB

An interesting discussion. As a long time user and proponent of the
TLAR method, I had not thought much about what the actual angles were.

Really easy to check with SeeYou and an IGC flight log. When I checked
my last 2 flights I found a pretty consistent 1km offset, with
altitude usually around 600 ft (opposite touchdown point, not pattern
entry). This is a 5:1 slope, about 12 deg. This is in a Ventus C.

Bob

On Sun, 12 Jul 2015 11:18:59 -0700 (PDT), wrote:

text deleted...

Just for curiosity, I looked at the recent landings at Hobbs of one of the competitors.
When he passed the touchdown spot on downwind on July 1, he was roughly 450'
?above it and 1900' away. This is a ratio of 1:4, not 1:1. The next day his numbers
were roughly 700' and 2200', for a ratio of 1:3.

I doubt if anyone can find many IGC files with numbers of 600' and 600'.

Well, that's the way I was trained in the Air Force and, as of today,
I've done it successfully 7,494 times. I guess it's not really as
dangerous as some would have you believe. Personally I find the long,
straight base leg to be much more difficult to execute well and much
easier to screw up. Your results may vary... :-D

On 7/12/2015 9:08 AM, wrote:
A 180 turn can definitely be performed within 600 feet, but then it has to be done quickly, with a good bank angle, and there is little room for adjustments in elevation. A safe 180 turn type of approach (naval aviator) requires (I think) bank angles that are less than 45 to have the room and time to adjust the rate of descent. In some way it is like having a curved base leg. But you may not do it safely if you are too close.
Please Dan correct me on this, I am not used to do the naval pattern.

--
Dan Marotta

Bob Gibbons wrote on 7/12/2015 5:10 PM:
An interesting discussion. As a long time user and proponent of the
TLAR method, I had not thought much about what the actual angles were.

Really easy to check with SeeYou and an IGC flight log. When I checked
my last 2 flights I found a pretty consistent 1km offset, with
altitude usually around 600 ft (opposite touchdown point, not pattern
entry). This is a 5:1 slope, about 12 deg. This is in a Ventus C.

Bob


I found the same thing in the 4 or 5 of my flights that I checked that I
flew in my ASH 26 E, generally turning onto the base leg at 1000' AGL. I
don't think I could get down in time if I were to use 45 deg angle to
the runway while on downwind, even with the 40 degree landing flaps and
good spoiler.

--
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
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

On Sunday, July 12, 2015 at 5:31:27 PM UTC-6, SoaringXCellence wrote:

A faster, higher L/D glider needs a lot more distance/time to dissipate energy and being 600' laterally abeam the touch down would create a significant challenge, both with the turns required to intercept final and the 45 degree base base turn reference.


Not really. EASA CS-22 paragraph 22.75 under which most high performance gliders were certificated says:

"It must be shown that the sailplane has a glide
slope not flatter than one in seven at a speed of
1·3 Vso with air brakes extended at maximum weight."

So basically all JAR-22/CS-22 gliders have less than 7:1 L/D with the spoilers open.

I've done several 45 degree angle of depression approaches with an early model DUO and it worked out fine.

Yes really. Starting 1000 ft agl at 1000 ft from the runway, and following the standard pattern, it would be 1000 ft to the turn to base, 500 on base turn, 400 on base, 500 on final turn and a 1000 for final. Total 3400 ft. opening full brakes for all this distance, at 1 on 7 you lose close to 500 feet. And you started at 1000 agl, so you are still 500 ft too high. You need more powerful brakes and flaps. But you shoudn't be using full airbrake during the whole pattern, it is better to use half.

Please check your traces on seeyou, or check how far you are from your home runway using google earth, a rough estimate is enough. You will be surprised.

I think you may be believing you fly with a 45 degree dip angle (1:1) to the runway when in fact it is more like 30 degrees (1:2). Just a matter of perception. As long as you keep it doing it like that you can call that angle 100 degrees or pi or a million, it is still safe. And if you teach somebody "this is the way it should look", that student will retain in his visual memory that angle, or slope, and it will be safe. But I am afraid of people measuring 600 feet from the runway (easy on google earth) and trying to fly a pattern at that distance next time, it is too close to the runway.

I believe you can land the Duo from 600 feet away. I don't believe you can have a real base leg when you do that.

It's always surprised me that the 360 overhead pattern hasn't been taught in glider flying, because it is probably the easiest way to setup a consistent pattern into an unfamiliar field.

The military way, you fly over the field at pattern height and above pattern speed, make a 180 turn once past your touchdown point, slow and configure on downwind (which is located by the radius of your turn at a higher than approach speed), then when the angle to the touchdown point "looks about right", do a 180 turn to final. No problem overshooting final (unless you neglect a strong crosswind) since you know you can do the same 180 turn (or 2 90s to check final) as you did to get your downwind distance. Easy to adjust by waiting for the right angle to the field to start the turn.

If you like a longer base, then just add a short crosswind leg after an intial 90 turn; your base will be about the same length (use time to set the distance, say a 5-count before the second 90 turn to downwind.

This is not new, militaries have been doing it since before WW2, and it has the beauty that it works anywhere with no ground references needed.

Unfortunately, if you do it at most glider fields with other glider traffic in the pattern you will probably fly you pattern way inside them and cut them off!

If you think about it, it's a variation of how XC students are taught to fly a pattern for an off field landing.

Finally, I really think glider pilots (well, all pilots) should be able to setup a successful landing from just about anywhere near the airfield, from a steep straight-in to a button-hook reversal when you realize the wind just switched directions.

It's called airmanship...

Kirk
66

As mentioned it is pretty easy to review IGC files and see what one is actually doing. I agree telling students to use about 45 degrees is good as that is what they will percieve it at. I am one that if asked would have said I was probably between 30 and 45 degrees abeam my touch down point. Seeyou says different here are the number for 7 of me recent flights.

Altitude(ft) Distance (ft) Angle(deg)
870 2904 16.7
1053 2270 24.9
1699 3326 27.1
1751 4540 21.1
823 1900 23.4
1072 3500 17.0
951 3273 16.2

average 20.9
minimum 16.2
maximum 27.1