Is there a nose hook modification for a standard cirrus

[wjsmi...@gmail.com]

I bought a standard cirrus. I havent flown it yet, but I was wondering if it's possible to put a nose hook on the plane?

[Dan Marotta]

Anything's possible, given time and money but (here we go again), why
would you want to do that?  Flame suit on...

On 10/4/2017 3:27 PM, wjsmi...@gmail.com wrote:
> I bought a standard cirrus. I havent flown it yet, but I was wondering if it's possible to put a nose hook on the plane?

--
Dan, 5J

[golfsie...@gmail.com]

There is a factory mod to fit a nose hook as described in Schempp Hirth TN 278-37.

In terms of why you'd want to, most Std Cirruses have a tailskid - tailskid and belly hook can be a challenging combination.

Nick.

[Scott Williams]

On Wednesday, October 4, 2017 at 4:27:58 PM UTC-5, wjsmi...@gmail.com wrote:
> I bought a standard cirrus. I havent flown it yet, but I was wondering if it's possible to put a nose hook on the plane?

Last year I spoke to Heinze of M&H the U.S. Schempp-Hirth Dealer, he thought kit, less Tost release would run $1500, Tost release maybe $500. Installation labor??

Heinze thought it would not be cost effective.
I bought the spoiler mod instead. My glider already had the hatch and wedekind sleeves.
Spoiler mod was worth twice what I paid IMO.

Good Lift,
Scott.

[Tony]

The only Cirrus I've seen in the US with a nose hook is UN, and I *think* they used a Zuni hook. Boy it looked nice.

[mark...@aol.com]

The CG hook "problem" on aero tow is an airport myth. Nose hooks are a hardware solution to a software problem. Spend your money elsewhere - like a pneumatic tailwheel or spoiler mod.

[michaelw...@live.com]

UN came with a Zuni or HP type hook installed by Applebay under a 337, that for those who aren’t familiar, kind of looked like a small Schweizer hook that retracts flush with the skin. The first time I attempted aerotowing with it, we tried twice to connect it with the line guy and it released and retracted when the towplane added power. The previous owner later said, yeah that happens sometimes, think the cable needs adjusted. I’ve also heard of Zuni accidents related to a possible premature release for what it’s worth. I taped over it and used the Tost CG hook without looking back. I figure Klaus knew what he was doing more or less.

Mike

[krasw]

On Thursday, 5 October 2017 06:08:14 UTC+3, mark...@aol.com wrote:
> The CG hook "problem" on aero tow is an airport myth. Nose hooks are a hardware solution to a software problem. Spend your money elsewhere - like a pneumatic tailwheel or spoiler mod.

Agreed, nose vs. cg hook is non-issue and gets way more attention than it really deserves. Most pilot woudn't notice any difference. Tail skid on the other hand is something that should have been left in 1910's and biplanes. Just horrible thing to have in anything, royal pain in the ass everytime it touches ground.

[Bruce Hoult]

Certainly in normal circumstances it isn't a problem.

In rotor with slack line I've pitch up when the rope suddenly becomes tight has been noticeable in a Janus, but easily dealt with.

Someone asked a while ago whether there was any history of towplane upsets with nose hook gliders. I don't recall that it was ever answered. You'd think that if it happens someone would be able to quickly point to an example or two.

[BobW]

Dunno if it was "kiting" in the sense of "torquing about the glider's CG" or
not, but I recall reading about a tow pilot fatality after a K-8 drove it into
the ground; happened in the 1960s in Utah. The article was given me as part of
a Safety Corner collection by my club's chief instructor for a
reading/feedback assignment during my primary instructional days. My takeaway
was: Kids, don't DO this!

I'd bet other instances in the U.S. - where nose hooks predominated for much
of soaring - can be found...

Bob W.

---
This email has been checked for viruses by AVG.
http://www.avg.com

[Tony]

oh god this subject again. Go back to the recent thread that Walt started about towplane upsets. Both of the gliders in his upset events had nose hooks.

[Craig Funston]

On Thursday, October 5, 2017 at 6:50:46 AM UTC-7, Tony wrote:
> oh god this subject again. Go back to the recent thread that Walt started about towplane upsets. Both of the gliders in his upset events had nose hooks.

Winter is coming
7Q

[Dan Marotta]

I had that combination on my LS-6a.  It was much simpler and cheaper to
swap the skid for a roller blade wheel.

--
Dan, 5J

[Dan Marotta]

Please describe the "spoiler mod".  Sounds interesting.

--
Dan, 5J

[Steve Leonard]

On Wednesday, October 4, 2017 at 10:20:21 PM UTC-5, michaelw...@live.com wrote:
> UN came with a Zuni or HP type hook installed by Applebay under a 337, that for those who aren’t familiar, kind of looked like a small Schweizer hook that retracts flush with the skin. The first time I attempted aerotowing with it, we tried twice to connect it with the line guy and it released and retracted when the towplane added power. The previous owner later said, yeah that happens sometimes, think the cable needs adjusted. I’ve also heard of Zuni accidents related to a possible premature release for what it’s worth. I taped over it and used the Tost CG hook without looking back. I figure Klaus knew what he was doing more or less.
>
> Mike

For what it is worth, Mike, I believe there has been one (not plural) Zuni accident attributed to pre-mature release that was likely related to the release itself. That one was missing a key component that, if not installed, assured that the release could operate on its own, with no pilot action required. I have now heard of two others that have behaved similarly (yours and one other). I have multiple hundreds of launches with my Zuni and have NEVER experienced a release that I did not initiate. Mine has all its parts, and is of a slightly different design that does not rely on a hidden spring that, if it is not there, you won't know it is not there and the release will malfuntion.

I am not sure when the design changed, but if all the parts are there and properly functioning, the release performs as designed and intended.

As for the "benefit" of a nose hook, well the rubber cover on my BS1 nose hook got torn, and I have not been successful at fab and install of a new cover, so I taped it over. Howled like a giant coke bottle. I now only use the CG hook, and have had no problems.

As someone else said, "It will cost a lot, and the benefit will be small". But sometimes for your own piece of mind, and benefit to others down the road, we just bite the bullet, spend the money and do something.

Steve Leonard
Zuni 2 Serial 28
Between 300 and 400 launches on my Applebay hook.

[Tony]

There is a tech note to add a second panel to the Std. Cirrus airbrake. Makes them much more effective. I did the mod almost as soon as we bought Kate.

[Bruce Hoult]

I thought it was in the early or mid 90s that absolutely every Cirrus at our club (six or seven of them I think) had a 2nd panel added to the airbrakes, all done in a batch over a couple of days.

[Dan Marotta]

Makes sense, thanks!

On 10/5/2017 10:27 AM, Tony wrote:
> There is a tech note to add a second panel to the Std. Cirrus airbrake. Makes them much more effective. I did the mod almost as soon as we bought Kate.

--
Dan, 5J

[son_of_flubber]

Is there an advantage to using a nose hook when aerotowing through rotor? A year or so ago, I ran the wing for a very_accomplished_glider_pilot in an LS-4 w/c.g.hook who the tow pilot said, went vertical UPish in rotor. The towplane went vertical DOWNish and broke the rope. Both came back to the airport.

Is a C.G. hook better in rotor?

[MNLou]

I would think the CG hook should have back released before the rope broke.

Lou

[swanso...@yahoo.com]

William,

Tow with a CG hook is no big deal. I haven’t seen your glider, but if you have a tail skid there is an easy way to replace it with a wheel.

http://fbw-flugzeugbau.de/parts-for-gliders-and-motorgliders/tail-wheels-for-Gliders/tail-wheels/Tail-wheel-complete-for-Std-Cirrus-Astir-CS-Nimbus-Discus-etc::560.html?language=enand

I have a wheel from these guys on my 19 and it’s excellent. We can talk more about the wheel and towing with a CG hook the next time we are both at the field. Its nothing to worry about.

John

[Dan Marotta]

It seems everyone concerned with CG hooks has some horror story about
gliders losing control.  I'll go out on a limb and lay that one squarely
in the lap of the pilot.  Sure, there aren't the self-righting forces
inherent in having the point of force far ahead of the CG, but a
competent pilot should be capable of correcting displacements from the
desired track or pulling the release.  If one's decision on purchasing a
glider is based upon whether or not the glider has a nose hook, I would
question the training or ability of the pilot.

On 10/5/2017 6:30 PM, son_of_flubber wrote:
> Is there an advantage to using a nose hook when aerotowing through rotor? A year or so ago, I ran the wing for a very_accomplished_glider_pilot in an LS-4 w/c.g.hook who the tow pilot said, went vertical UPish in rotor. The towplane went vertical DOWNish and broke the rope. Both came back to the airport.
>
> Is a C.G. hook better in rotor?

--
Dan, 5J

[Aaron Thomson]

Hi,

I have a Nimbus 2B that is certified with a nose hook installation. I can look through my records for the 337 if you would like.

Aaron Thomson
N71TT Nimbus 2B

[Andy Blackburn]

On Friday, October 6, 2017 at 9:39:49 AM UTC-7, Dan Marotta wrote:
> It seems everyone concerned with CG hooks has some horror story about
> gliders losing control.  I'll go out on a limb and lay that one squarely
> in the lap of the pilot.  Sure, there aren't the self-righting forces
> inherent in having the point of force far ahead of the CG, but a
> competent pilot should be capable of correcting displacements from the
> desired track or pulling the release.  If one's decision on purchasing a
> glider is based upon whether or not the glider has a nose hook, I would
> question the training or ability of the pilot.
>
>

> --
> Dan, 5J

It can happen pretty fast - no matter how quick you are on the release. Particularly with a ballasted wing, a tip skid instead of a wheel and if you are more than 100' down the runway when it happens and have a head of steam.

I have no idea how much a nose hook might help. You can end up off the runway without generating much of a difference in path angle. My advice is to brief any wing runner you haven't used before - they have a lot of influence over the ultimate outcome.

Andy Blackburn
9B

[Tim Taylor]

In general the cg hook is not an issue on S-H gliders if the glider is correctly set-up. The important things that need to be checked and done:
1. Replace a tail skid with a tail wheel.
2. Make sure the tail wheel is rubber and not hard plastic like some of the early models.
3. The tail wheel needs to be aligned with the glider so that it tracks straight. This can be tested by holding the wings level and pushing the glider on a flat surface for several hundred feet. No deviation should be found.

If all of the above have been done the glider should track straight on normal take-off. You can also hold back on the stick during the initial few seconds of roll to help hold a straight line in cross-winds until more rudder athority is gained and the tail is raised.

[Dan Marotta]

Of the 5 pure sailplanes I've owned, only one had a nose hook and, in
thousands of hours of gliding, I can not recall ever wishing I had a
nose hook on any of the others.  Nor did I ever think of how great a
nose hook is except when ground launching.  Statements like "no matter
how quick you are" are not useful and only serve to demonize something
that has been used successfully since the earliest times in gliding.

No matter how quick you are someone can still pull out in front of you
on the road such that you can not avoid an accident.  Does that make you
not drive?  Of course not.  You rely on your abilities and observation
of the world around to anticipate and avoid, to the extent possible,
such happenings and to react to those that do.  The same is true in
gliding.  I do not object to nose hooks only to the notion that they are
"safer" than the alternative.  And I've seen plenty of hose hook
equipped gliders take a trip into the rough.

--
Dan, 5J

[jpg...@gmail.com]

Maybe some might think differently about the wisdom of fitting nose books to all gliders (where possible) if they had lost a colleague to a kiting belly hook equipped glider he was towing.

When a tow is going normally it makes little difference where the hook is but when the glider has begun to kite it makes a big difference.

[Darryl Ramm]

On Saturday, October 14, 2017 at 11:23:33 AM UTC-7, jpg...@gmail.com wrote:
> Maybe some might think differently about the wisdom of fitting nose books to all gliders (where possible) if they had lost a colleague to a kiting belly hook equipped glider he was towing.
>
> When a tow is going normally it makes little difference where the hook is but when the glider has begun to kite it makes a big difference.

That is an excellent point. It can also make a difference in marginal take-off conditions, crosswind, narrow strips, long grass, stuff you might find on an aero retrieve, etc. And low time/new pilots especially may not have the judgement to not try that, especially if they see other gliders towing from there.

Can you aero tow a glider easily with a CG hook? Sure you can. Are there benefit to having a nose hook? Sure there are. Should you install one... uh depends (Clubs and low-time pilots I would hope err on the side of having nose tow hooks).

[Frank Whiteley]

In a club ship, if there is a nose-hook option, installation should be done. We have an LS-4b that came with only a CG hoot. It took a while, but eventually a member took a launch excursion and nearly collided with some private gliders on the launch point tie-downs. A factory kit was ordered and installed.

I mentioned previously that many years ago at least three Colorado Std Cirrus owners had 'bras' that slipped over the nose and were retained by the CG hook and were towed from the front of the 'bra'. Upon release, rope and 'bra' followed the tow plane home. At the time, they probably didn't have a retrofit option.

Frank Whiteley

[krasw]

All this anecdotal evidence is pretty useless. We might guess that something might or might not happened if there is nose hook but in the end it is just that. A guess.

[Dan Marotta]

Falsies on a glider!  Who'da thunk it?

--
Dan, 5J

[golfsie...@gmail.com]

I think it's reasonable to question whether or not the cost of the kit is worthwhile compared with the gain. But it's pretty difficult to argue that there isn't some gain.

In recent years there have been very few production gliders delivered without a nose hook and powerful airbrakes. Essentially, the 2 Schempp-Hirth technotes that cover these items give a Standard Cirrus owner the opportunity to modernise their glider if they choose.

Cheers,
Nick.

[krasw]

On Sunday, 15 October 2017 20:19:57 UTC+3, Jonathan St. Cloud wrote:

> On Sunday, October 15, 2017 at 5:49:48 AM UTC-7, krasw wrote:
> > All this anecdotal evidence is pretty useless. We might guess that something might or might not happened if there is nose hook but in the end it is just that. A guess.
>

> I wonder if you caught the irony in your declaration. I would offer that multiple parties with similar experiences is a statiscally valid trend.

Statistical data would be like "we have a group of Std.Cirrus gliders with nosehook and similar group with C/G hook, and we can say that this group exhibits XX accidents during tow per 100000 hrs, and other group YY accidents per 100000 hrs". Or something to that effect.

[Andreas Maurer]

On Mon, 16 Oct 2017 01:17:26 -0700 (PDT), krasw
<kristia...@gmail.com> wrote:


>Statistical data would be like "we have a group of Std.Cirrus gliders with nosehook and similar group with C/G hook, and we can say that this group exhibits XX accidents during tow per 100000 hrs, and other group YY accidents per 100000 hrs". Or something to that effect.

100% agree.

For 25 years my club has had two DG-300: One with nose hook and one
without. We had exactly one incidence where a DG-300 got the tow plane
out of control by pulling up its tail.

It was the one with the nose hook.

[jpg...@gmail.com]

So, Andreas, do we conclude the the physics and maths of tow hook placements are wrong or that there is always someone who sometime can manage to do something especially stupid?

[herbk...@gmail.com]

Andreas, pre Newtonian physics (Galileo) suggest that the nose hook is providing more stability, no non-stochastic statistics necessary to prove that! Why is it so hard to accept that you're better off with the tow line attached to a point far forward of the cg? Anecdotal stories are BS.

[Tango Whisky]

Of course a nose hook provides a little bit more of stability.
Now, if you *need* this little delta to stay safe, you shouldn't be flying solo in the first place.

[Dan Marotta]

Amen!

Using simple engineering (physics, if you like), the CG hook is about 1
foot displaced from the CG of the glider.  Assuming around 25 lb of
force applied to that arm (after the initial force required to overcome
inertia during acceleration (and you're on the ground at that time with
the tail wheel resisting the torque)), that yields about 25 lb-ft of
torque.  That's really not much to overcome.

It is my opinion that the real cause of a kiting incident is that the
glider pilot is either asleep at the helm and doesn't recognize what's
happening or that he wants to salvage the tow to avoid inconvenience or
expense.  Say all you want how quickly this develops, that too is anecdotal.

--
Dan, 5J

[uncl...@ix.netcom.com]

"True" nose hook is higher and more in line with the center of mass, thus reducing the pitching force when rope tension is really high. This helps with kiting to a degree. It is possible to yank hard enough that this pitching force can exceed the ability of the horizontal tail to overcome, especially at high weight and aft CG. Dick Johnson did an article about this in late '86 or early '87.
Also provides some straightening effect in yaw obviously.
FWIW
UH

[chip.b...@gmail.com]

> "True" nose hook is higher and more in line with the center of mass, thus reducing the pitching force when rope tension is really high. This helps with kiting to a degree. It is possible to yank hard enough that this pitching force can exceed the ability of the horizontal tail to overcome, especially at high weight and aft CG. Dick Johnson did an article about this in late '86 or early '87.
> Also provides some straightening effect in yaw obviously.
> FWIW
> UH

Per UH's note, see Dick Johnson's Tail "Stall While Towing", Soaring mag, May 1987. For those who aren't aware, Dick's article arose from discussions I had with him and (independently) Air Force test pilot Jim Payne following Robert Robertson's fatal towing accident in 1986. I had spoken to each about my suspicion that there was more going on in that tragic accident than just all-up weight, CG, or tow speed. Both experts reached the same conclusion: i.e., in some circumstances, a robust tow plane, high/ballasted glider weight, CG towhook, and/or slower tow speed could possibly make the tail susceptible to stalling, with disastrous consequences.

To this analysis I offered another twist, with not much agreement in this group: if the glider pilot were hanging on, nose high, with the stick in his/her lap desperating hoping for the tow speed to increase and then decided to give up and release, then pushing the stick over might itself trigger tail stall because of the near instantaneous increase in effective elevator angle of attack resulting from the up-to-down change in elevator deflection.

Years ago, my LS-3 popped the nose up sharply for a moment rolling out behind a powerful towplane just as I lowered the flaps to lift off and we flew out from behind a row of hangars that had sheltered us from the wind. In that case, a quick full-forward-stick motion reversed the incipient kiting (I could never recall whether I moved the flaps back to zero, but that would have helped) and my heart rate returned to normal.

As far as directional control, I've been flying gliders with CG hooks since 1978 (LS-3, ASW 24). I never thought having a nose hook was a big deal until I rolled off the runway last summer in Nephi after my wing dropped early with full water ballast. I'm not sure if a nose hook would have provided enough steering force to prevent hitting a landing light. But I could have avoided doing so simply by releasing, as I've done several times before (and once since!).

We do mostly aerotow here in the U.S. A CG hook isn't unsafe. But if I had the choice, I'd take a nose hook just because of the modest benefit.

Chip Bearden

[Andreas Maurer]

On Tue, 17 Oct 2017 01:47:08 -0700 (PDT), jpg...@gmail.com wrote:

>So, Andreas, do we conclude the the physics and maths of tow hook placements are wrong or that there is always someone who sometime can manage to do something especially stupid?

Well...
let me put it this way:

As you probably know, the test flights that proved that the nose-up
momentum of a CG hook have been made by a German Akaflieg (project
pilot was a friend of mine, btw). And of course these flight tests
(using a Ka-8) proved that using a CG hook indeed made a huge
difference.


But:
Based upon these flight tests Germany introduced a law that aerotows
on CG hooks were only allowed if the pilot had recent aerotow
experience (3 aerotows during the last 6 months), and of course new
gliders had to be equipped with a nose hook.

Many people assumed that these limitations would affect aerotow safety
in a positive way. But it turned out that there was no influence of
these new rules on aerotow safety, not was there ever a hard
statistical proof that gliders with a CG hook had a higher aerotow
incident rate than gliders with nose hook (the odd man out being some
notorious gliders with problematic geometry and CG hook, especially
the Ka-6).


So last year this law was removed.


My conclusion:
In theory and flight test the maths and physics are correct, but in
practics they are not related to incident numbers.



p.s.
I usually fly an open class double seater with only a CG hook, and my
club's ASK-21 and Duo Discus XL. When teaching upset aertow situations
in the ASK-21 I never noticed any useful stabilizing effect of the
nose hook, nor did Iever in the Duo Discus. The same goes for the
DG-300 with and without nose hook which I had many chances to compare.

[Dan Marotta]

The only real advantage I can see to a nose hook is to the ground
crewman who doesn't have to lay on his back to attach the rope. :-D

--
Dan, 5J

[kirk.stant]

Gliders with CG hooks are kinda like airplanes with tailwheels; if you know what you are doing they are no problem and can be more fun (i.e. need more skill) than nose hooks or nose wheels.

BUT

They both can setup situations that can rapidly escalate out of control. Crosswinds, unbalanced wings dropping, poor aileron control at low speed, tall grass - you have to be aware of the system dynamics and prepared to cope.

Now if we had CG hooks on towplanes..!

Kirk
66

[Frank Whiteley]

I have seen a concept sketch for a specialty tow plane, automotive powered, large prop driven by a reduction drive, and cg tow tow hook and twin boom tail. Only a few hurdles to overcome, like FAR's (allow experimental to tow) and/or certification (difficult) and limited market. Break even point would be about 200 builds. It could equal or beat on of these as a tow plane
https://en.wikipedia.org/wiki/SIAI-Marchetti_SM.1019

Keep the CG hook and buy a winch is easier and cheaper.

Winter's coming;^)

Frank Whiteley