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eightyknots

Steel Bungee Replacement for Zenith Aircraft

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587787841_steelbungee.jpg.2e1d5479f237123ae8a0a31822179fd1.jpg

 

I came across this recently. I was wondering if anyone has contemplated (or actually replaced) their standard bungee with the permanent steel one from Viking?

 

http://www.shop.vikingaircraftengines.com/Zenith-parts_c36.htm

 

 

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Looks a bit heavy! Need a new W&B after this one.

Here is a bit of extra information: http://www.shop.vikingaircraftengines.com/Steel-Bungee-for-Zenith-aircraft-Zenith-spring.htm .

 

The important thing is weight. By removing the original and replacing it with this, how much net weight gain will there be? I think a W & B is probably warranted.

 

 

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Here is a bit of extra information: http://www.shop.vikingaircraftengines.com/Steel-Bungee-for-Zenith-aircraft-Zenith-spring.htm .

The important thing is weight. By removing the original and replacing it with this, how much net weight gain will there be? I think a W & B is probably warranted.

I think there is a bit more to consider than that. If you look at that link, you will see this "The Preloading of the spring is handled internal to the spring, using an adjustable rod, providing no force to the airframe while in flight. The ramp effect of the original plastic material has been milled away and the steering arms now ride on a flat surface.". The ramp effect is there for a reason. It is a bit of a pain, but it is also necessary. With the all flying tail, you need a centring force on the rudder, and that's what the ramps are for. Milling them flat is altogether too casual an approach. If that is done, you will need to provide some centring springs for the rudder pedals. Unlike the ramps, these will provide additional resistance to turns when taxying. It is one of the disagreeable aspects of the 701's handling in flight, that there is such a self centring tendency, but not having it can be more disagreeable.

 

Other than that, it looks like one of the better thought out ideas from Jan, and it is even reasonably priced.

 

Regards,

 

Paul

 

 

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If anything is weak on the Zen STOL's it's the nose gear and the bungee! I don't like it, never have but since I'm going to put on amphibs in the near future I was never too worried about it. I've had issues with Jan but this is one of his better ideas. Reports are that milling the block causes no issues, but if you are worried about it I'm sure you can leave it as is. The steering (rudder) is tight while the weight is OFF the nose, it's actually easier to move on the ground. The pre-load option makes it easier to move in the air. I'm looking at getting this, but I'd probably leave the notch in the block anyways. If it's greased up well, it's usually not that bad. My $0.02. :)

 

 

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If anything is weak on the Zen STOL's it's the nose gear and the bungee! I don't like it, never have but since I'm going to put on amphibs in the near future I was never too worried about it. I've had issues with Jan but this is one of his better ideas. Reports are that milling the block causes no issues, but if you are worried about it I'm sure you can leave it as is. The steering (rudder) is tight while the weight is OFF the nose, it's actually easier to move on the ground.:)

That's what I said - "Unlike the ramps, these [centring springs] will provide additional resistance to turns when taxying.".. :)

 

The ramp angles are there by design, not accident, so it is cavalier to remove them without knowing why they are there, don't you think? The least one should do is talk it over with Caleb. They don't mind you reducing the angle some...

 

The nose bungee does wear out - but it doesn't do so without warning, and it usually fails gracefully. I don't have the ring on my nose leg, as I want the full travel and that restricts it unnecessarily and can result in a bent leg (and prop). I've put a 45 degree bend in my nose wheel axle as a result of a vicious gust - the bungee part and the rest of the structure seemed quite content. As it was a graceful enough failure, I replaced it with another as per the plans, though I have made a stronger one as a spare in case it starts forming a habit.

 

For a very light aircraft, the coil spring set up does look a bit heavier than a lacky band... weight control is pretty high on my list of priorities.

 

Are you making your own floats? I've seriously thought about putting water skis on, there is a good body of test data on "universal landing gear", with wheel penetrating skis to operate on water, snow, etc All you need is a little beach to taxi to and from. I know it sounds quite mad, but there was considerable real world testing on it in the fifties, that was supplanted by further development of helicopters.

 

Cheers,

 

Paul

 

 

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Here are the most up to date pictures of the steel bungee for the CH-701 from Viking Aircraft.

 

1.jpg.4f69a6473d064672ff508ee737f56a88.jpg

 

2.jpg.36ca74b28c685b6406313238c2e8e502.jpg

 

3.jpg.d80cdafb669795c744bffce126f91cbc.jpg

 

4.jpg.998a8f7f9220e6e448aad19fdff9173b.jpg

 

5.jpg.4b171e14816aa78ef7d92bdac0e547f0.jpg

 

I think they are well worth thinking about.

 

 

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I think there is a bit more to consider than that. If you look at that link, you will see this "The Preloading of the spring is handled internal to the spring, using an adjustable rod, providing no force to the airframe while in flight. The ramp effect of the original plastic material has been milled away and the steering arms now ride on a flat surface.". The ramp effect is there for a reason. It is a bit of a pain, but it is also necessary. With the all flying tail, you need a centring force on the rudder, and that's what the ramps are for. Milling them flat is altogether too casual an approach. If that is done, you will need to provide some centring springs for the rudder pedals. Unlike the ramps, these will provide additional resistance to turns when taxying. It is one of the disagreeable aspects of the 701's handling in flight, that there is such a self centring tendency, but not having it can be more disagreeable.

Other than that, it looks like one of the better thought out ideas from Jan, and it is even reasonably priced.

 

Regards,

 

Paul

 

Hi Paul

 

I have just flown with similar unit to the Viking spring. Yes, you are right, no need to mill out the V, because the rudder feel comes OK once the bungee is removed And you are right on ground handling - I surprised myself a bit on landing first time so better use ballet slippers than workboots. Not really, but it is much lighter with the spring than with the bungee so a light touch on the pedals is needed. I had 900hrs with bungees, never go back...

 

Peter

 

 

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Hi Paul

I have just flown with similar unit to the Viking spring. Yes, you are right, no need to mill out the V, because the rudder feel comes OK once the bungee is removed And you are right on ground handling - I surprised myself a bit on landing first time so better use ballet slippers than workboots. Not really, but it is much lighter with the spring than with the bungee so a light touch on the pedals is needed. I had 900hrs with bungees, never go back...

 

Peter

Thanks for the info Peter.

 

 

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Fitted my own version today with an australian spring,( 200grm lighter).

 

Works beautifully & no need to touch ramps, still within W/B tolerance.

 

 

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Hi Jabirupilot,

 

Any chance of some pics of your version?

 

 

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Hi Jabirupilot,

Hi Marty, basically the same as the viking but different enough to not run foul of copyright.

 

Using steel springcap instead of aluminium & Aust made spring of round wire instead of rectangular.

 

Next time the cowl is off, will try to get ya a piccy. Not as pretty as the viking but still effective.

 

Cheers Roger.

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Has anyone in Australia made a Savannah version of the spring bungee replacement.

 

 

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Fitted my own version today with an australian spring,( 200grm lighter).Works beautifully & no need to touch ramps, still within W/B tolerance.

Now I remember. Thanks for the pics!

 

 

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Have any of the

 

Now I remember. Thanks for the pics!

Subject: Latest from Viking

 

Latest from Viking

 

SteelBungee.PNG

 

200th Steel Bungee sold

 

IMG_4353.JPG?width=750

 

Viking Turbo 170 Flying through its first 200 hours

 

Viking130finalperformace.png?width=750

 

Compare with UL 350 max torque of 236 ft.lb to Viking 130 at 286 ft.lb

 

TurboEnginePicture.png?width=750

 

170 HP to altitude. The Viking 170

 

1.5turbochartwithotherengineson1.0bar.png?width=750

 

Viking Turbo engines - 460 ft.lb at 2000 prop rpm

 

 

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Have any of the 200 buyers of the steel bungee ever weighed the new Viking bungee and compared the weight with the original Zenith bungee?

 

If so, what are the weights?

 

 

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From memory, it was 1.5 Kg heavier than the bungee. Just add that to your nose wheel weight and re-calc W&B

 

 

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