New 360 wing fillet available

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Re: New 360 wing fillet available

Postby J Wales » Fri Mar 23, 2018 9:56 pm

George Catalano wrote:Ya but VG's can't accomplish what this mod is intended to accomplish.
Which is what? Which is what? (minimum character count)
Last edited by admin on Fri Mar 23, 2018 10:00 pm, edited 1 time in total.
Reason: please add quotes so someone can follow the topic
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Re: New 360 wing fillet available

Postby Bob Fidler » Sat Mar 24, 2018 8:02 am

.It is my understanding the goal of this mod is to reduce drag of the 300 series Lancairs. The fuselage behind the cabin reduces in size in a short distance which tufting studies have shown creates turbulence in the airflow. Less turbulence, less drag is the goal and most Lancair guys believe it works and add a few knots of speed.
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Re: New 360 wing fillet available

Postby Craig Schulze » Sat Mar 24, 2018 10:25 pm

Has anyone flown with this?
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Re: New 360 wing fillet available

Postby Bob Fidler » Sun Mar 25, 2018 6:07 am

Craig Schulze wrote:Has anyone flown with this?

I was assuming that the mold was made from a flying aircraft with the mod, but a conversation with him should happen. I will ask him.
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Re: New 360 wing fillet available

Postby George Catalano » Sun Mar 25, 2018 11:59 am

Much like the Legacy - the 360 fuselage narrows too quickly and there is a large airflow disturbance at the wing trailing edge/fuselage interface. I tufted my plane and took videos - it is definitely there. Especially when you start adding alpha - it goes nuts back there.
All of the super fast Legacys have the 'beluga belly mod' as they affectionately refer to it. It has a documented 8-10 knots no BS speed benefit on the fast Legacies. STIHL racer has a video somewhere that shows the tufts before and after - very clearly showing the turbulence on the tufts going away with the mod.

The theory, so I am told, is that the fuselage should have the same width along the the cord of the wing and only then should start to narrow and taper. The air crossing over the wing needs to finish the work it is doing (lift) before it has to diverge into a new direction. Anyone want to chime in with real aeronautical knowledge that would great - because I am only repeating what works at Reno and what I have been told. :roll:

In the 'for-what-it's worth department' -- Tom McNerney's 360 has a design similar to the Legacy's which he designed and built himself - since he implemented many mods all at the same time he couldn't account for an exact speed delta but what he clearly noted was that the plane did not decelerate in the same manner any longer nor slow as much when the G's were applied going around the pylons at Reno.
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Re: New 360 wing fillet available

Postby Brent Hudgin » Mon Mar 26, 2018 11:16 am

They have not flown yet. The molds were made from CAD files. Håkan designed them and has them installed on his airplane that hasn’t flown yet. Eric has installed them on a plane that hasn’t flown also (pictured in the first post). Neither plane will be able to verify a speed gain since they didn’t fly without them. I am still considering flying my plane in primer before installing the fillets to satisfy my curiosity about the gains. Regardless, my plane is still a ways away from getting in the air. I will absolutely post here when somebody flies them.
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Re: New 360 wing fillet available

Postby Roger Iverin » Tue Mar 12, 2019 9:26 am

Any updates for this mod ?
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Re: New 360 wing fillet available

Postby Erno Ovari » Tue Mar 12, 2019 2:22 pm

Craig Schulze wrote:Has anyone flown with this?


Tom flies his mod.
http://www.n54sg.com/beluga-belly-modification/
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Re: New 360 wing fillet available

Postby J Wales » Mon Mar 18, 2019 9:28 pm

Is 5 kts worth that much work? :stir:
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Re: New 360 wing fillet available

Postby Gabriel Silverstein » Tue Mar 19, 2019 12:36 am

I have long wished our IV-PT was even more like this than it is. Mooneys and Cirri (plural for Cirrus, right?!) are a great example of why this makes sense. A Cirrus shape does what the Lancairs do, whereas a Mooney continues mostly straight lines all the way back, and it's not just because it's metal and not composite - it's faster by design. It's not just pressure and airflow direction differences the current shape creates, it's also a longer distance laminarly (is that a word?) from front to back than if there was no reverse curve and instead just a straight line to the tail (remember that the shortest distance between two points is a straight line). The less distance air travels to depart contact at the back, the less drag it can exert along the way.

Ours is very curvaceous, John Cook's (the fastest IV-PT ever made) has more of this boxy shape, especially on the belly where on his the existence of a belly tank isn't noticeable because there is no bulge, he didn't try to "shrink wrap" the skin around the parts. Mooney I think figured out a long time ago you don''t need to reverse the curve because it's actually slower - look at a Mooney tail (boxy). I also believe that an angle (harder chine?) of some sort (vs. soft curve) between the horizontal and vertical surface areas acts as a subtle fin, and also limits non-longitudinal airflow, where we should always want airflow to be along the longitudinal axis.

Of course, I'm just a finance guy, but racing sailboats and flying planes I have seen multiple instances where less aesthetic design (slab-sided boats, this topic, etc.) is somehow almost always faster than curves. I think that's one of the reasons the Evo is slower than the IV-PT generally, the fuselage curve needs to be more slab-sided as it progresses down from its apex width to join the wings, and there needs to be a long(er) filet extending back from the back of the wing joint towards the tail to force longitudinal air flow where the wing and fuselage join on the aft portion of the wing as air flowing above and below the wing rejoin. The IV-P design does a pretty good job in that spot, the Evo must have some terrible airflow right there.
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