Glidepath73 From Germany, joined Mar 2005, 1018 posts, RR: 49 Posted (8 years 2 weeks 3 hours ago) and read 3012 times:
Hi all,
I just thought about the possibility to add winglets on the horizontal stabilizer.
I think at least for (over)longhaul airliners, it would lead to a reduced fuel burn, since the same might happen as on the wings.
What do you guys think about? Was this tested before in windchannel tests?
Are there some guys from aerodynamic engineering, which could let us know more about it?
Glacote From France, joined Jun 2005, 409 posts, RR: 2 Reply 3, posted (8 years 1 week 6 days 4 hours ago) and read 2760 times:
A properly designed wing is always better without winglets. You put winglets whenever:
- you want to update an existing wing profile without going through a complete revamp
- you have geometrical constraints (e.g. 80m for the A380)
Thus you could try to add winglets on an outdated elevator but the cost savings vs a full revamp and the expected gains are not worth it - you either rebuild a whole new elevator or you do nothing at all.
AeroWeanie From United States of America, joined Dec 2004, 1601 posts, RR: 52 Reply 7, posted (8 years 1 week 5 days 20 hours ago) and read 2453 times:
Quoting Glacote (Reply 3): A properly designed wing is always better without winglets. You put winglets whenever:
- you want to update an existing wing profile without going through a complete revamp
- you have geometrical constraints (e.g. 80m for the A380)
Wrong!!! Winglets are just nonplanar span extensions. Any wing will benefit from a span extension.
DfwRevolution From , joined Dec 1969, posts, RR: Reply 9, posted (8 years 1 week 5 days 19 hours ago) and read 2413 times:
Quoting Glidepath73 (Reply 4): Was in your opinion the 330/340 wing not properly designed?
Airbus designed the A330/A340 without winglets, but implemented them during an extensive redefinition when IAE dropped the ball big time with the IAE SuperFan engine. Airbus was counting on the SuperFan to meet their performance goals, and when the only engine available was the CFM56-5, they needed enhancing features to avoid missing their targets.
Glidepath73 From Germany, joined Mar 2005, 1018 posts, RR: 49 Reply 11, posted (8 years 1 week 5 days 18 hours ago) and read 2332 times:
Hi guys,
thanks a lot for your opinions.
Lets say we add winglets at the stabilizer of a 772LR or a 345. Would the a/c need more fuel, same, or less for about the same distance? (Weight shouldn't be that much, since we have composites)
Abbs380 From United States of America, joined Mar 2005, 120 posts, RR: 0 Reply 13, posted (8 years 1 week 5 days 8 hours ago) and read 2195 times:
AsstChief Mark, Your pic is a 747 Shuttle carrier. I think these are actually extra vertical stabilizers which are out of the wake of the shuttle when its being carried. I dont think they are intended as a performance enhancement, just extra stability.
Keta From Germany, joined Mar 2005, 444 posts, RR: 0 Reply 14, posted (8 years 1 week 5 days 8 hours ago) and read 2191 times:
Quoting AeroWeanie (Reply 7): Wrong!!! Winglets are just nonplanar span extensions. Any wing will benefit from a span extension.
That's what I was going to say
Quoting SATL382G (Reply 12): Horizontal stabilizers don't produce lift, they produce down force.
That's like saying that they produce negative lift, the effect is the same.
Quoting Glidepath73 (Reply 11): Lets say we add winglets at the stabilizer of a 772LR or a 345. Would the a/c need more fuel, same, or less for about the same distance? (Weight shouldn't be that much, since we have composites)
Depending on the aircraft's CG, speed, weight, altitude... the stabilizers produce lift, negative lift or no lift at all. What kind of winglets would you put? On the wings, the lift is always an upwards force, but on the stabilizers it can be downwards. Kind of tough to design a winglet that would benefit in both cases. Maybe wingtip fences could do that?
I'm not sure, but I'm afraid the vortex created are small, since the aerodynamic force is not very big. The weight is a thing you always have to take into account. I guess the aerodynamic savings would not be sufficient to justify the increase on weight.
Jetlagged From United Kingdom, joined Jan 2005, 2462 posts, RR: 17 Reply 16, posted (8 years 1 week 5 days ago) and read 2147 times:
The best way to reduce the drag of the horizontal stabiliser is to have it produce as little lift (and so induced drag) as possible. The less lift is produced, the less a winglet will help.
Endplate fins used to be used a lot in aircraft design, in the search for better efficiency. In the days before winglets, endplates were known to reduce induced drag, but usually their weight and form drag overcame any real advantage.
Apart from the endplate effect, part of the idea was to put the fin in the propwash to improve the rudder effectiveness (as with the Lodestar above). Not such a good idea with a jet
The glass isn't half empty, or half full, it's twice as big as it needs to be.
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