Ventus b flap sealing

[George Underhill]

Hello fellow first gen Ventus owners. I'm removing and replacing the seals on the lower wing surface of my Ventus b. The previous installation had tape (perhaps teflon) from the wing to the flaps, but no mylar seal. The ailerons currently have both tape and mylar kombi seals. I'm using Streifeneder's drawing to as a guide to install the new seals. What installations are other Ventus a and b owners using on the flap gap? If installing mylar on the flaps are there any problems when deploying full spoiler and the resultant large flap angle pinching or bending the mylar?

I've seen photos online, as well as Schempp-Hirth Ventus C/Nimbus 3 drawings, of a two layer seal with aft and forward facing mylars. The rolling S seal seems like a good idea, but too involved to get done.

Thanks for sharing your setup.

[Frank Whiteley]

On Tuesday, March 30, 2021 at 9:13:01 AM UTC-6, wrote:
> Hello fellow first gen Ventus owners. I'm removing and replacing the seals on the lower wing surface of my Ventus b. The previous installation had tape (perhaps teflon) from the wing to the flaps, but no mylar seal. The ailerons currently have both tape and mylar kombi seals. I'm using Streifeneder's drawing to as a guide to install the new seals. What installations are other Ventus a and b owners using on the flap gap? If installing mylar on the flaps are there any problems when deploying full spoiler and the resultant large flap angle pinching or bending the mylar?
>
> I've seen photos online, as well as Schempp-Hirth Ventus C/Nimbus 3 drawings, of a two layer seal with aft and forward facing mylars. The rolling S seal seems like a good idea, but too involved to get done.
>
> Thanks for sharing your setup.
IIRC, Dick Johnson recommended using both the mylar and the internal S seals. That said, I found the mylars in place of the s-seals were fine and improvement. Kestrel 19, not Ventus.

[George Underhill]

Thanks for the reply Frank.

The configuration I'm removing was a tape of some sort on the flap to wing gap with conventional tape and mylar on the ailerons. All of this is bottom surface only. My concern is with the wing to flap angle and whether the mylar would get pinched or bent. Dick Johnson did report "Excellent factory-installed air seals were evident along the elevator, aileron, and flap hinge lines and at the flap/fuselage juncture," in his December 1981 review of the Ventus a in Soaring magazine. I'm not sure whether mylar was over the seal or not. The seals and mylar I'm removing are the GFS system from Streifeneder and have been on a long time.

[Christopher Gough]

On Tuesday, March 30, 2021 at 3:18:06 p.m. UTC-6, wrote:
> Thanks for the reply Frank.
>
> The configuration I'm removing was a tape of some sort on the flap to wing gap with conventional tape and mylar on the ailerons. All of this is bottom surface only. My concern is with the wing to flap angle and whether the mylar would get pinched or bent. Dick Johnson did report "Excellent factory-installed air seals were evident along the elevator, aileron, and flap hinge lines and at the flap/fuselage juncture," in his December 1981 review of the Ventus a in Soaring magazine. I'm not sure whether mylar was over the seal or not. The seals and mylar I'm removing are the GFS system from Streifeneder and have been on a long time.

I have mylar top and bottom on mine. The mylar hasn't come off yet from the brake's movement.

I don't have the internal fabric tape that the factory installed. I believe a previous owner removed it when they removed the flaps and ailerons for refinish.

Chris

[George Underhill]

On Tuesday, March 30, 2021 at 8:58:12 PM UTC-5, wrote:
> On Tuesday, March 30, 2021 at 3:18:06 p.m. UTC-6, wrote:
> > Thanks for the reply Frank.
> >
> > The configuration I'm removing was a tape of some sort on the flap to wing gap with conventional tape and mylar on the ailerons. All of this is bottom surface only. My concern is with the wing to flap angle and whether the mylar would get pinched or bent. Dick Johnson did report "Excellent factory-installed air seals were evident along the elevator, aileron, and flap hinge lines and at the flap/fuselage juncture," in his December 1981 review of the Ventus a in Soaring magazine. I'm not sure whether mylar was over the seal or not. The seals and mylar I'm removing are the GFS system from Streifeneder and have been on a long time.
> I have mylar top and bottom on mine. The mylar hasn't come off yet from the brake's movement.
>
> I don't have the internal fabric tape that the factory installed. I believe a previous owner removed it when they removed the flaps and ailerons for refinish.
>
> Chris

Thanks Chris.

No internal rolling S seals on my Ventus either. I mocked up a small section of the seal and mylar on the flap and it looked like it will work ok. I don't think my Ventus b (SN 37) has ever had any sealing on the upper surfaces.

[krasw]

Mylars do not seal the gap, to create airtight barrier you need that s-tape.

[George Underhill]

On Wednesday, March 31, 2021 at 1:32:53 AM UTC-5, krasw wrote:
> Mylars do not seal the gap, to create airtight barrier you need that s-tape.

Yes, I'm aware the mylar doesn't do the sealing. That's what the teflon tape is for, under the mylar.

[Dave Nadler]

On 3/31/2021 2:32 AM, krasw wrote:
> Mylars do not seal the gap, to create airtight barrier you need that s-tape.

Right, mylar+teflon helps but does not seal completely on these gliders.
Its some decades back, but IIRC the rolling seal was an option,
and did help with performance (but a maintenance nuisance).
If you're working on seals anyway, consider adding the rolling seal if
not already equipped...
Hope that helps,
Best Regards, Dave

[George Underhill]

On Wednesday, March 31, 2021 at 2:20:57 PM UTC-5, wrote:
> On 3/31/2021 2:32 AM, krasw wrote:
> > Mylars do not seal the gap, to create airtight barrier you need that s-tape.
> Right, mylar+teflon helps but does not seal completely on these gliders.
> Its some decades back, but IIRC the rolling seal was an option,
> and did help with performance (but a maintenance nuisance).
> If you're working on seals anyway, consider adding the rolling seal if
> not already equipped...
> Hope that helps,
> Best Regards, Dave

Thanks for the input Dave,

I'm not sure the rolling seal is worth the effort and expense. I'm not that good to know the difference : ) I might have to remove the flap and inner aileron to fix an issue with play in the actuating rod at the aileron connection, but that's a different story.

Dick Johnson's Ventus A review mentions factory seals along the hinge line, but he didn't mention the rolling seal that is evident in the aft wing root photo in the article. The flap to fuselage junction has mylar also, which mine is lacking, although it does have rubber boots inside the fuselage on the flap actuating tube.