Ventus 2 undercarriage?

[John McLaughlin]

The undercarriage lever seems reluctant to stay in it's detent with the
wheel down - it'll pop out with the lightest touch and the wheel has been
known to retract, going over a bump.

One option is to push a wooden wedge against the lever, to hold it in
place,
but does anyone know if there's a better fix available? I believe the
Ventus
3 has a spring to hold the lever outboard - is that an option for fitting
to the
2?

[stu8...@gmail.com]

I put a door stop with a tether on mine.

Simple seems good.

[Ken Fixter]

At 12:52 18 February 2019, stu8...@gmail.com wrote:
>I put a door stop with a tether on mine.
>
>Simple seems good.
>

> Better look fo the real cause of the problem, may be worn joint parts
redusing the over centre locking action, look at the mechanism in the wheel
bay.
KF.

[jjd...@yahoo.com]

I would look to see what's out of adjustment, bent or worn and repair it correctly.
Wooden wedges, doorstops and Bandaids are seldom the cure.

JG

[markm...@gmail.com]

And let's not forget the application of epoxy, fiberglass, carbon fiber and money in extreme cases.

[johnsin...@yahoo.com]

The down stop (located at the handle) has become rounded off due to wear. This stop should be re-worked or replaced. You may be able to file it back to original shape which is more than 90 degrees. Most all SH ships have this problem after about 10 years in service.. Look at the rounded off corner, it should be about 100 degrees. Its probably made of 1/8” hard plastic. I have “adjusted” this stop with a triangle file and made it a rather sharp 100 degrees again. Badly rounded stops need to be replaced which I have done by making a new one out of 1/8” aluminum bar. Check the “over-center mechanism after you adjust the stop by trying to collapsed the gear. This is done with the ship in its trailer saddle, then shoving forward on the drag links at the rear. It should not move more than about an inch, then snap back again into overcenter position. Adjust this by making the down motion longer (half turn) at a time at the most convient rod-end fitting.
Hope this helps,
JJ

[AS]

I have to admit that I have not worked on a Ventus undercarriage but I worked on a good number of other ones. They all have one thing in common and that is a classic 'over-center' design, which keeps the struts locked in place when the gear is extended and loaded. The actuating levers and rods are most likely never meant to bear the loads imparted onto the gear mechanism upon landing!
I would recommend you check the degree of over-center, which may be adjustable. Also, in most all cases, there is some kind of a spring or gas strut involved, which holds the over-center in position. Using a door stopper may make the symptoms go away but it does not fix the problem.

Uli
'AS'

[Tim Taylor]

I agree that the over center should be checked and adjusted. Following that, I would install a locking spring. I have installed them on every S-H I have owned. I have had gear retract on rough landings and extend in turbulence. I once had a very rough take-off in the Ventus 2 where on one last bounce the gear handle came out of detent, the fully loaded glider started to settle but I was lucky and had just achieved flying speed.

A locking spring is very simple to design and install. Use a large clip spring retainer and several Adel clamps mounted to the seat pan.

[GliderCZ]

Not sure that this applies to the detent problem, but are you aware of the SH Technical Notes 349-25 and 360-17? They refer specifically to potential gear retraction on landing if shock struts are fully compressed. It says: "It is possible that the tyre can touch the bolts of the strut and also the horizontal cross bar of the aft undercarriage strut. Due to this the undercarriage mechanism will come under loadings in the retracted position and may fail under unfavourable conditions."


There is a fix in the minor modification of the crossbar, but the same effect can also be attained by fitting a narrower, slightly smaller diameter tire. I got mine from Wings and Wheels: 336X115-5 TOST-AERO Tire (5.00X5). I had a gear collapse prior, happily on turf, although gear doors were damaged.

The fix is well described and illustrated in an appendix to those same TNs. I'm not a mechanic and don't play one on TV, so please confer with your favorite A&P/IA.

Incidentally, I still use an appropriate block in the detent space as insurance.

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

Don't know the SH gear but as several have mentioned, the over center feature seems common to all. In the LS series, the pivot bolts in the gear can get a little stiff with age, grit, and lack of lubrication. The damper strut can get stiff when it's cold, which is designed, I believe, to prevent the gear from vibrating out of the over center position but can also inhibit it snapping into the locked position. And the gas spring that is the actuator itself can lose up to 50% or more of its rated force, which means the gear isn't being pushed into and held in the over center position as forcefully. When you touch down with a little bump...auto-retract occurs!

For LS (1, 4 and 3 that I know of), the combination of weak gas spring and stiff damper strut (both exacerbated by cold) are bad news. Stiff linkages just make it worse. Extend the gear and then look at it from below. If you can push the struts into the locked-down, over-center position that last little bit by hand, there's a problem. Fix that first. Some of the same may be true for other makes. My ASW gear easily goes over center and has a positive lock at the lever. But when down on the ridge, I have to wedge something into the gap by the lever to prevent a big bump from knocking the lever out of the detent and allowing the wheel to drop with an alarming noise.

Chip Bearden

[markde...@gmail.com]

It can be tempting for someone hoping to make it easier to get the gear into the “up” position to adjust the linkage using the threaded rod end on the back end of the gear handle.

The threaded rod end should only be used to make sure that the handle allows correct positioning when the gear is in the down and locked position. Specifically that the aft linkages on the gear assembly are fully extended and firmly blocked agaist each other. You must inspect the gear linkages to verify this.

As a result, the “up” position is singularly controlled by the length of the plate that is bolted to the under side of the composite “shelf” that the gear handle rests against. If that plate has worn down then replacing that plate is necessary. As others have mentioned, replacing the plate with an aluminum piece may yield a more robust assembly.

When the gear assembly is down and locked, if the handle is slightly tight against the plate, that will help guard against it jostling loose as will ensuring that the corner of the plate is sharp and the forward edge being very slightly angled against the handle rotating out of detent.

Good luck!

[krasw]

Landing on the moon: no problem whatsoever. Glider landing gear that works: sorry it's just not possible.

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

Back in the mid-late 60s (1967?), my father had one of the first Diamants in the U.S., a 15 Meter HBV model (with the Libelle 301 wings). The gear collapsed one day when it was about 6 months old for no apparent reason. He and his partners flew it a few times with the gear locked down using a hose clamp secured around one of the actuators (can't recall details). Functional but noisy and not very elegant (not far removed from not flying it at all).

It wasn't until the factory rep arrived (IIRC, Fred Jiran in what may have been his first visit here) to do some factory mandated mods that he discovered the landing gear frame had gotten bent slightly in a ground loop. The downlock activated by folding the gear retract handle against the wall of the cockpit was no longer engaging. Most times the legs being over center was sufficient to keep the gear down...but not always.

Chip Bearden