Fuselage lift

Wondering how much if any lift in gliders is generated from the fuselage in flight. There is a famous photo of a F-15 that landed with one wing gone due to collision. This of course was possible due to the lift generated by the F-15 fuselage.

The Schleicher family of gliders had two new fuselages designed in the mid 1990's (ASW-24 and ASH-26). Scheme-Hirth, fuselages take their linage from the original ventus designed in the late 1970's (wing roots added in later designs, tail feathers modified with ventus 2cx.)

Seems like all new designs of gliders focus on the airfoil, wing shape and winglets, but I wonder how much if any design improvements are not realized due to improvements that could be made in lift and drag of fuselage designs.

Jonathan years back we had a zuni which we extebsively modified. The zuni had a large slightly bulbous one piece canapy and something if a turtledeck in the fuselage begind the cockpit. We cut down the canapy and reprodiled the fuselage to attempt to get some uniform flow over the fuss top between the wings. In flight it made a noticable improvement and when we tuffed the area it showed good attachment.
Dan

On Sunday, March 20, 2016 at 11:29:34 AM UTC-4, Jonathan St. Cloud wrote:
Wondering how much if any lift in gliders is generated from the fuselage in flight. There is a famous photo of a F-15 that landed with one wing gone due to collision. This of course was possible due to the lift generated by the F-15 fuselage.

The Schleicher family of gliders had two new fuselages designed in the mid 1990's (ASW-24 and ASH-26). Scheme-Hirth, fuselages take their linage from the original ventus designed in the late 1970's (wing roots added in later designs, tail feathers modified with ventus 2cx.)

Seems like all new designs of gliders focus on the airfoil, wing shape and winglets, but I wonder how much if any design improvements are not realized due to improvements that could be made in lift and drag of fuselage designs.

The fuselage is there to hold the pilot and connect the parts. Beyond those purposes the only thing it adds is drag. As far as lift, it needs to not screw it up- that's it. It is pretty hard to do much better than the Schleicher fuselage without reducing cockpit size.
I'll make a bold prediction that the new "full size" fuselage for the New Ventus will have a much thinner tail boom and tighter waste. We'll see.
FWIW
UH

On Sunday, March 20, 2016 at 11:29:34 AM UTC-4, Jonathan St. Cloud wrote:
Wondering how much if any lift in gliders is generated from the fuselage in flight. There is a famous photo of a F-15 that landed with one wing gone due to collision. This of course was possible due to the lift generated by the F-15 fuselage.

The Schleicher family of gliders had two new fuselages designed in the mid 1990's (ASW-24 and ASH-26). Scheme-Hirth, fuselages take their linage from the original ventus designed in the late 1970's (wing roots added in later designs, tail feathers modified with ventus 2cx.)

Seems like all new designs of gliders focus on the airfoil, wing shape and winglets, but I wonder how much if any design improvements are not realized due to improvements that could be made in lift and drag of fuselage designs.

The F-15 also has a total lifting area of a tennis court, and was travelling substantially faster. The wing in the F-15's case is much more integrates and spread across the fuse, whereas most glider fuselages generally match a tapered 50 caliber shell and blend the wings on. As UH said, all the fuse is doing is keeping you attached to the wings and trying to minimize drag.

Beg to differ, the substantial increase in performance we gained in the zuni isnt an isolated case. Some of the older folks here may be familiar with the early bellanca cruisair series of aircraft. The bellanca cruisair when new would cruise at 150 mph on 150 hp franklin engine. This is for a four place built like a brick ****house wood and tube aircraft of the late 1930's.. Part of the efficiency of guiseppe bellanca's designs was based upon a fuselage planform that was in itself a lifting surface. As for the 50 cal analogy, definitely applicable to the trans-sonic and sonic regions of the flight envelope but not the most efficient shape for subsonic flight.

On Sunday, March 20, 2016 at 3:12:18 PM UTC-7, wrote:

The fuselage is there to hold the pilot and connect the parts. Beyond those purposes the only thing it adds is drag. As far as lift, it needs to not screw it up- that's it. It is pretty hard to do much better than the Schleicher fuselage without reducing cockpit size.
I'll make a bold prediction that the new "full size" fuselage for the New Ventus will have a much thinner tail boom and tighter waste. We'll see.

I was told somewhere along the line that the forward fuselage of the current generation of Schleicher single-seaters was designed in such a way that it allowed the horizontal stabilizer to be significantly reduced in size - with a corresponding reduction in parasite drag. I was never able to substantiate the claim, but the horizontal stab on my ASW-27 is pretty compact compared to older generation gliders. I suppose it could also have something to do with the tail design and airfoil itself.

Also FWIW.

9B

I have heard an urban legend that the schleicher fuselage, while built to accommodate small to X-Large pilots, still has less wetted area than a SH a model fuselage. I have no idea if this is true.


On Sunday, March 20, 2016 at 5:41:51 PM UTC-7, Andy Blackburn wrote:
On Sunday, March 20, 2016 at 3:12:18 PM UTC-7, wrote:

I was told somewhere along the line that the forward fuselage of the current generation of Schleicher single-seaters was designed in such a way that it allowed the horizontal stabilizer to be significantly reduced in size - with a corresponding reduction in parasite drag. I was never able to substantiate the claim, but the horizontal stab on my ASW-27 is pretty compact compared to older generation gliders. I suppose it could also have something to do with the tail design and airfoil itself.

Also FWIW.

9B

At the recent SSA conference Jonkers spoke about a new version of their fuselage coming out soon. They have lowered the nose and reshaped the canopy to generate a little bit of lift. A side benefit is increased forward visibility. At least that was my understanding of what he was explaining. It did not seem to be just drag reduction.
Chris

On Sunday, March 20, 2016 at 8:29:34 AM UTC-7, Jonathan St. Cloud wrote:
...This of course was possible due to the lift generated by the F-15 fuselage.

I think that the most important factor was that the F-15 has elevons that deflect differentially as a roll control. The elevon on the side with the missing wing was basically carrying half the airplane.

Think of it this way: If you pitched a one-winged F-15 up enough to get any substantial amount of fuselage lift, the remaining wing would produce enough lift roll it like a pinwheel.

Thanks, Bob K.

Horizontal stab size has nothing to do about fuselage shape (other than tailboom length). It's all about ability to winch launch. If you skip that, you can put very small one to your glider. Concordia uses 27 stabilator and I bet they have no plans for winch launches.

Schempp will install self-launching Solo to bigger Ventus fuselage, there will be no possibilities for tight waist because of that. It will most likely be Ventus2c/Quintus -type fuselage.