Of tow hooks and wheel brakes

At 21:13 09 June 2013, Tony wrote:
Pulling the release before things get out of hand is pretty cheap, like I
d=
id on day 2. Brakes are like Goldilocks if you want to stay out of the
repa=
ir shop. Too weak and here comes the fence at the end of that field. Too
st=
rong and there's a hole in your nose after the wheels lock up.

Yep simple rule of thumb. If your glider has a nosewheel then fit a brake
as strong as you like. If you do not have a nosewheel, as in most single
seaters fitting a strong brake is really a waste of time and money because
you cannot use it. Even the "weak" brakes fitted to gliders such as the
discus can only be used with care.

On 6/9/2013 4:02 PM, Don Johnstone wrote:
At 21:13 09 June 2013, Tony wrote:
Pulling the release before things get out of hand is pretty cheap, like I
did on day 2. Brakes are like Goldilocks if you want to stay out of the
repair shop. Too weak and here comes the fence at the end of that field. Too
strong and there's a hole in your nose after the wheels lock up.

Yep simple rule of thumb. If your glider has a nosewheel then fit a brake
as strong as you like. If you do not have a nosewheel, as in most single
seaters fitting a strong brake is really a waste of time and money because
you cannot use it. Even the "weak" brakes fitted to gliders such as the
discus can only be used with care.

Having once owned a tail-dragging glider with "world's best brake" I can vouch
that having an "overly powerful" *and* easily modulatable brake is a wonderful
combination. (It was a hydraulically-actuated drum brake on a homebuilt HP-14.)

It was powerful enough to put the plane on its nose, while simultaneously
sufficiently modulatable as to (easily) permit braking heavy enough to lift
the tail without pitching onto the nose. Combined with world's most powerful
landing flaps, the plane was a joy to land, despite its Vee tail-feathers and
veering into crosswind tendencies (in which case I generally angled into the
wind as much as practicable, touched down with minimal safe energy and fell
more in love with large deflection flaps and the superb wheel brake)...

Bob W.

On Sun, 09 Jun 2013 16:44:23 -0600, BobW
wrote:

[snip]
Having once owned a tail-dragging glider with "world's best brake" I can vouch
that having an "overly powerful" *and* easily modulatable brake is a wonderful
combination. (It was a hydraulically-actuated drum brake on a homebuilt HP-14.)

+1 on "easily modulatable". My first glass bird had a drum actuated by
a motorcycle squeeze grip on the stick, and its cable was pitifully
stretchy...by the time I got to a very moderate brake application, the
handle would hit the stick and stop. I finally found it was identical
to the one sold for the CLUTCH linkage on a 125cc Bultaco motorcycle.

I finally found a cable assembly that had larger gauge cable and a
stronger housing, and it worked pretty well.

Besides, if the barbed wire is coming up, putting the ship up on the
nose will be OK with me, thank you very much.

On Sunday, June 9, 2013 4:02:31 PM UTC-6, Don Johnstone wrote:
If you do not have a nosewheel, as in most single seaters fitting a strong brake is really a waste of time and money because you cannot use it. Even the "weak" brakes fitted to gliders such as the discus can only be used with care.

You can not use the breaking power you do not have, but you can modulate the extra breaking power you do have. Better a scraped nose than a busted glider. And having a nose hook also lowers the odds of having to release and use all the braking power.

Having flown tail wheel gliders with too little and with too much power I prefer the one with too much braking power.

Robert Mudd

Another element I have observed is that many pilot wait until the end of the run to try the brakes.

At that point the elevator has no authority to keep the tail down. Better to hold aft stick with braking while you still have control of the pitch, earlier in the ground roll. This allows you to keep the tail down.

I know that with the ships I fly that are "tail draggers" the sooner you get rid of energy the easier the end of the ground roll.

It's a different approach than most pilots seem to use but it works well.

SoaringXCellence wrote, On 6/9/2013 5:14 PM:
Another element I have observed is that many pilot wait until the end
of the run to try the brakes.

At that point the elevator has no authority to keep the tail down.
Better to hold aft stick with braking while you still have control of
the pitch, earlier in the ground roll. This allows you to keep the
tail down.

I know that with the ships I fly that are "tail draggers" the sooner
you get rid of energy the easier the end of the ground roll.

It's a different approach than most pilots seem to use but it works
well.

On my ASW 20 C, I would put the flaps in negative after touching down
and hold the stick back, allowing full braking power with no chance of
going up on the nose. Wait to end, the elevator wasn't very effective at
holding the tail down, reducing the braking force I could apply without
the nose going down - like Xcellence said.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

You can not use the breaking power you do not have, but you can modulate the extra breaking power you do have.
That's sure the Truth! I love the G103 hydraulic disc brake! Unfortunately, I fly a Speed Astir most of the time, which uses the same miserable Tost Kobold Wheel the LS3 and 4 use. Stretchy cables aside, I have never seen a Tost Kobold wheel that DIDN'T have cracks in the steel (iron?) brake drum portion of the wheel. The Tost BIMBO wheel is nothing more than a scaled up Kobold. Of course, I have one of those in the Janus.
Vintage Brake can make the drum brakes work well (a fiend's libelle brake is very powerful (after Vintage Brake treatment), even though it's the tiny Lilliput wheel.
The downside is the wait. He runs a 4 month backlog most of the time. I don't know what he can do if the drum has the cracks that are so common.