The International Cessna 170 Association

Hi,

In my previous post I mentioned that 4489B was a Wings with Springs airplane. I had never heard of this before and figured I'd share, see the attached brochure. Earl Metzler of Pennsylvania created an STC to replace struts of various aircraft with hydraulic cylinders, primarily to make flight through turbulence smoother, although there were some additional side benefits with variable dihedral. While he successfully installed the struts on several makes and models and they were apparently very effective at smoothing out bumps, the idea never really caught on.

He completed this STC on 4489B and used it as a demonstrator, as pictured in the advertising.

The hydraulic struts have since been removed from 4489B as the previous owner didn't like the look of the wings drooping while the plane was on the ground.

-Ryan Harris

Cool! Do you still have them? If so, wanna sell them?

DEM

Did the developer of the "Wings With Springs" ever receive an approved STC for this system? I have never heard of it before.

Curious concept, but I think this is one of those inventions of which necessity was not the mother.

I have heard of these, but never saw an actual airplane with them installed. I wonder if any were sold?

It seems the idea never " took off" . I wonder what the wing dihedral was when fully loaded and what amount of lift was lost .

I wonder how the flap and aileron cable tensions were maintained as the wings pivoted. Googling "Cessna wings with springs" it appears he found few buyers but those that did swore by the device.

I did a bit more searching through my stack of paperwork on 4489B and the google last night.

There are articles from Flying 1948 and Flying 1959 that provide some of the story. Metzler came up with the idea in the 1930s and by 1948 had installed this successfully on an Aeronca. It looks like he patented the idea for both high and low wing airplanes in 1952. The later Flying magazine article says that this was officially certified in 1957, probably on Taylorcrafts. I have some handwritten notes that say 8 Taylorcrafts had the spring struts installed.

The spring struts were installed on 4489B in 1960 and the plane was certified as experimental. In 1964, this was approved as STC# SA175EA and 4489B received a standard airworthiness certificate again at that point. A press release states that 4489B was the first "modern" airplane to receive the spring struts and would start a new wave in aviation. The handwritten notes say that 5 Cessnas had spring struts installed. I think the others were 180's and 182's.

I do not have any of the spring strut pieces, I would guess they were thrown away when 4489B was converted back to regular struts in the 90s.

-Ryan

This seems nuts to me. Are the wing attach fittings modified with bearings to handle the constant motion? Do the flap and aileron cables change tension? What about fuel lines, wing root fairings, etc.?

Here's a link to a book called "A Place in the Sky", with a brief history of this invention. I can think of a few flights I'd like to have had shock absorbers in the wings.

I can well remember the spookyness fo the wing flap in the old Boeing B-47. It was engineered, if memory serves, to a fail point of 22 ft.

blueldr wrote:I can well remember the spookyness fo the wing flap in the old Boeing B-47. It was engineered, if memory serves, to a fail point of 22 ft.

https://www.youtube.com/watch?v=6cIgTAtj4E4

Aerobatics in a B-47. Video shows the wing flexing up and down considerably. Impressive bomber.

Thanks for the video, David. I had vever seen it before, but I don't remember ever being told that my unit was going to use that bombing method.

That was a great video to watch! I had never seen that one before and had no idea that the B-47 was ever flown like that. Pretty much makes the Boeing 707 Barrel roll over Lake Washington seem pretty tame.

Bill

Something makes me feel VERY uneasy about wings with springs

I pass.

However I feel the need for a tip of the Hat to the inventor.

He had a Passion for Aviation that he kept alive. Persistent passion kept alive among the naysayers.

He was awarded a STC.


New innovations in aviation are right before us. Bring it on.

Regards