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Double-hinged flap explained or shown??

Posted: Sun May 08, 2022 4:18 pm
by convair880mfan
In Terry Waddington's book on the DC-10, page 106, he describes a DC-10-60 series of planes pitched to the airlines but never developed. He writes: "But the biggest change was to the flap system. Its small vaned version of the standard DC-10 was [to be] replaced by a double-hinged flap that increased chord during takeoff and landing."

Can someone explain to me what a double hinged flap is, how it works and if it is used on any aircraft or better yet share a photo of such a device? I managed to find a patent for a double hinged flap on the internet but it is hard for me to understand. Thanks in advance for any information.

Re: Double-hinged flap explained or shown??

Posted: Sun May 08, 2022 6:36 pm
by hitower3
Dear Convair,

I am not entirely sure if the author may not have meant "double slotted flaps", as the DC10's flaps were single slotted.

If it was indeed about double hinged flaps, the idea could have been an implementation of a NASA patent from 1967:
https://ntrs.nasa.gov/citations/19700032700

I hope this helps...
Hendric

Re: Double-hinged flap explained or shown??

Posted: Sun May 08, 2022 8:33 pm
by kalvado
As far as I understand, dc-10 has Fowler flaps which pivot on a hinge below lower wing surface. While mechanics is totally unlike flap tracks used on today's A-B jets, surface movement is somewhat similar. There are no slots to be seen, but mechanics looks like that could be incorporated.
I can imagine - no proofs though - how that can be redesigned to 2 moving surfaces moving around different axis and\or different angles, possibly with slots.
This all is totally unlike patent quoted above, where 2 axis are both within the airfoil crossection.
Looks like IL-86 has something similar to what I have in mind

Re: Double-hinged flap explained or shown??

Posted: Sun May 08, 2022 10:00 pm
by DL_Mech
A good picture showing the lower hinge point and the actuators inside the flap fairings.

https://www.flickr.com/photos/caribb/2591747496

Re: Double-hinged flap explained or shown??

Posted: Sun May 08, 2022 11:48 pm
by convair880mfan
Thanks to you all for the responses. Do you think a double hinged flap would simply be a duplicated lower hinge or do you think perhaps there would be an upper and lower hinge? Is there an upper hinge on the flaps of the Douglas DC-8? Sorry that I am not very smart abut such things.

Re: Double-hinged flap explained or shown??

Posted: Sun May 08, 2022 11:53 pm
by kalvado
[twoid][/twoid]
convair880mfan wrote:
Thanks to you all for the responses. Do you think a double hinged flap would simply be a duplicated lower hinge or do you think perhaps there would be an upper and lower hinge? Is there an upper hinge on the flaps of the Douglas DC-8? Sorry that I am not very smart abut such things.

Try sketching how airfoils move in MD-11 picture @dl_mech linked, how that relates to movement of flaps in more modern design.
I bet you will answer a lot of your questions that way.

Re: Double-hinged flap explained or shown??

Posted: Mon May 09, 2022 12:07 am
by convair880mfan
Ok. Are these things on the wing of the DC-8 upper surface wing hinges or on the aileron?


Re: Double-hinged flap explained or shown??

Posted: Mon May 09, 2022 12:52 am
by kalvado
convair880mfan wrote:
Ok. Are these things on the wing of the DC-8 upper surface wing hinges or on the aileron?


It's a different type of hinged design
A good animation of hinged Fowler flaps is here. On a slightly newer plane, though:
https://youtu.be/zyf-pb3qZwo

Re: Double-hinged flap explained or shown??

Posted: Mon May 09, 2022 1:12 am
by Starlionblue
kalvado wrote:
As far as I understand, dc-10 has Fowler flaps which pivot on a hinge below lower wing surface. While mechanics is totally unlike flap tracks used on today's A-B jets, surface movement is somewhat similar. There are no slots to be seen, but mechanics looks like that could be incorporated.
I can imagine - no proofs though - how that can be redesigned to 2 moving surfaces moving around different axis and\or different angles, possibly with slots.
This all is totally unlike patent quoted above, where 2 axis are both within the airfoil crossection.
Looks like IL-86 has something similar to what I have in mind


Would this be an "offset hinge flap" like, AFAIK, the 787?

Re: Double-hinged flap explained or shown??

Posted: Mon May 09, 2022 2:03 am
by kalvado
Starlionblue wrote:
kalvado wrote:
As far as I understand, dc-10 has Fowler flaps which pivot on a hinge below lower wing surface. While mechanics is totally unlike flap tracks used on today's A-B jets, surface movement is somewhat similar. There are no slots to be seen, but mechanics looks like that could be incorporated.
I can imagine - no proofs though - how that can be redesigned to 2 moving surfaces moving around different axis and\or different angles, possibly with slots.
This all is totally unlike patent quoted above, where 2 axis are both within the airfoil crossection.
Looks like IL-86 has something similar to what I have in mind


Would this be an "offset hinge flap" like, AFAIK, the 787?

Yes, looks like 787 and md-11 have similar flap design principles. I actually linked 787 video above.