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Author Topic: RES-Dart, Flying Wing, F3-RES (Hyperflight, Zeller Models, Bimminger)  (Read 400 times)
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Konrad
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« on: September 19, 2018, 05:22:26 PM »

Should I damage my Chrysalis lite F3-RES ship and with the lead times it takes me to finish a model, I thought I’d start my next F3-RES ship.
http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=22619.0

As I have a problem with the skid induced roll of the typical RES ship the Dart RES by Jose Bimminger from Zeller Models looks like it should be a good fit for me.

I got my kit from Hyperflight in the UK. I need to thank Neil Stainton for all his help in getting this to me. I was very surprised at how fast it arrived, less than a week after the bank card cleared.
And much to my surprise, despite the rhetoric form the USA President there was no added tariff.
https://www.hyperflight.co.uk/products.asp?code=RES-DART&name=res-dart-flying-wing

The Dart-RES is a great looking kit! All the wood is of a very very high caliber. Looks to be the right weight and grain for the expected part. I have to admit that there is about twice as much wood in the Dart -RES as in the Chrysalis -lite F3-RES. This concerned me but I think much of this is in the way of assembly aids. There is an included foam assembly fixture to keep the ribs at the correct angle to the LE.

I got the kit with the carbon DSA tubes as I can’t for the life of me understand why the German ruling body claims that they violate the carbon content of the F3-RES rules. This Dart has 1/10 as much carbon as my American Chrysalis-lite!

All the best,
Konrad
Attached files Thumbnail(s):
RES-Dart, Flying Wing, F3-RES (Hyperflight, Zeller Models, Bimminger)
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dosco
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« Reply #1 on: September 23, 2018, 03:51:44 PM »

OOooh. The RES Dart. I like the lines of that ship, and the videos I've seen of it flying are mesmerizing.

-Dave
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« Reply #2 on: September 24, 2018, 05:06:30 AM »

That looks interesting Konrad. I'm curious to see how it performs. DSA tubes - I checked out the links on the hyper light site and have a vague idea of what they are supposed to do. My German is just not good enough Smiley

I've never seen a wing launch as well as that on a bungee - but it does have a low wing loading.

John
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Konrad
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« Reply #3 on: September 24, 2018, 09:19:15 AM »

OOooh. The RES Dart. I like the lines of that ship, and the videos I've seen of it flying are mesmerizing.

-Dave

Yep, that dancing on the wing tip, and how it out flew that "Keep RES Simple” was so inspiring!
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« Reply #4 on: September 24, 2018, 09:45:49 AM »

Unless they have been able to rewrite the rules of aero design that have prevented flying wings from being competitive thermal ships in the past, it will be just another fad design. It might be better at one specific thing, but conventional design is the best balance of performance. The fact that part of the wing, which usually creates lift, has to be repurposed for pitch control during certain phases of flight in a flying wing means that you have almost insurmountable obstacles between your plane design and contest level performance. Neat plane but it will get destroyed by equal pilots flying conventional designs.
« Last Edit: September 24, 2018, 09:57:43 AM by VictorY » Logged
Konrad
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« Reply #5 on: September 24, 2018, 10:31:13 AM »

That looks interesting Konrad. I'm curious to see how it performs. DSA tubes - I checked out the links on the hyper light site and have a vague idea of what they are supposed to do. My German is just not good enough Smiley

I've never seen a wing launch as well as that on a bungee - but it does have a low wing loading.

John
I too have always been attracted to the “Flying Wing” despite her idiosyncrasies. Like having a lighter wing loading but still can’t launch as high off a winch. Way back in the late 80’s I had a Klingberg 100 wing. Loved that she had flaps and a variable center of gravity. But my Sagitta 100 would out fly her at most TD contests. Mainly because of the performance on the winch. But from any given altitude and in the same air the Klingberg 100 wing flew better than the Sagitta, again as a result of the lighter wing loading and lower drag.

The RES-DART should be a lot of fun. Not sure how the DSA tubes will actually work. I’m concerned with the Reynolds number working against the airflow inside those tubes. Like is there any flow on that inboard wing tip?

I recall the Horten brothers mentioning middle effect with raked back wings. I wonder if the RES-Dart fuselage addresses this. Or should I add a classic Horten center section stinger?
Attached files Thumbnail(s):
Re: RES-Dart, Flying Wing, F3-RES (Hyperflight, Zeller Models, Bimminger)
« Last Edit: September 24, 2018, 10:59:58 AM by Konrad » Logged

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Konrad
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« Reply #6 on: September 24, 2018, 10:47:51 AM »

Unless they have been able to rewrite the rules of aero design that have prevented flying wings from being competitive thermal ships in the past, it will be just another fad design. It might be better at one specific thing, but conventional design is the best balance of performance. The fact that part of the wing, which usually creates lift, has to be repurposed for pitch control during certain phases of flight in a flying wing means that you have almost insurmountable obstacles between your plane design and contest level performance. Neat plane but it will get destroyed by equal pilots flying conventional designs.
The whole wing is used to produce lift. Roll Eyes

True part of the “flying wing’s” wing is used to produce a positive pitching moment. As opposed to a conventional wing that has negative pitching moment. Hence the performance killing need of a stabilizer.

It’s all about drag. And the fact that the RES format places a huge drag penalty of conventional aircraft needing to yaw to turn. The Elevon RES format is at a huge advantage in flight.

Like I said The Sagitta was a dog against the Klingberg 100 inch wing once they were both off the winch. But since the Sagitta would launch to a greater height, if the air was dead or bad she would win most TD contests.

The RES format might just be that set of rules.
I know in pylon racing most rules outlaw the flying wing and/or delta because of its great performance.

All the best,
Konrad
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VictorY
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« Reply #7 on: September 24, 2018, 11:24:20 AM »

"The whole wing is used to produce lift" Not during maneuvering. The change in pitch is caused by reflexing a large portion of the airfoil which means that it's not available for camber changing function to keep the lift to drag ratios optimized throughout the turn. Even in a conventional RES, where the trailing edge is solid, the entire wing is optimized for lift at all times. Every time you input up elevator in a flying wing, you lose airfoil fidelity, something you are obsessed with the short time I've been reading your posts and interacting with you. The small amount of drag induced by conventional stabs is more than offset by the wing maintaining it's lift to drag efficiency for a greater portion of the flying time. Please, explain to me why flying wings don't dominate electric launch sailplane competitions now. Take the winch out of the equation.
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VictorY
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« Reply #8 on: September 24, 2018, 11:46:02 AM »

The other thing you have to consider, since they don't create as much lift as conventional wings, is you need more area to carry the same weight. This is fine if you are cruising in a straight line at an optimized airspeed, but when maneurvering and changing airspeeds, the extra area creates more drag than a properly built fanny on a conventional plane with less wing area.
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Konrad
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« Reply #9 on: September 24, 2018, 11:54:02 AM »

The other thing you have to consider, since they don't create as much lift as conventional wings, is you need more area to carry the same weight. This is fine if you are cruising in a straight line at an optimized airspeed, but when maneurvering and changing airspeeds, the extra area creates more drag than a properly built fanny on a conventional plane with less wing area.
I think you are trying to say that they (flying wings) can't reach the same coefficient of lift.
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Konrad
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« Reply #10 on: September 24, 2018, 12:10:57 PM »

"The whole wing is used to produce lift" Not during maneuvering. The change in pitch is caused by reflexing a large portion of the airfoil which means that it's not available for camber changing function to keep the lift to drag ratios optimized throughout the turn. Even in a conventional RES, where the trailing edge is solid, the entire wing is optimized for lift at all times. Every time you input up elevator in a flying wing, you lose airfoil fidelity, something you are obsessed with the short time I've been reading your posts and interacting with you. The small amount of drag induced by conventional stabs is more than offset by the wing maintaining it's lift to drag efficiency for a greater portion of the flying time. Please, explain to me why flying wings don't dominate electric launch sailplane competitions now. Take the winch out of the equation.
What? Even durring maneuvers there is lift over the whole span of the wing. (Maybe not in the post stall) I think you are confusing camber with lift.
As to ELS I haven't read the rule book.
I will say that having read many speed and racing rules, more often than not the "flying wing" is banned. Because of its speed advantages, lower drag over conventional lay outs.  

Anyway we (I) shall see how these contemporary designs perform. I'm sure (I hope) they don't fly the same. It will be fun to learn to fly to the strengths of each design. That is what good pilots do. And those that do that the best often are found on the winners podium. Wink
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VictorY
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« Reply #11 on: September 24, 2018, 12:21:22 PM »

I'm not confusing anything. To create the pitching force, a portion of the wing either has to lose lift completely, or create negative lift. A conventional design requires very little downward force, hence the tiny area of horizontal stabs on racing gliders, because it has long moment arm. And that force is acting on a wing that is creating maximum lift across it's entire span. There is no comparison in thermal competition. That why the baddest plane on the planet in high lift conditions looks like this, and not a flying wing. https://www.aopa.org/news-and-media/all-news/2012/august/09/groundbreaking-sailplane-soars-at-world-championships
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Re: RES-Dart, Flying Wing, F3-RES (Hyperflight, Zeller Models, Bimminger)
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« Reply #12 on: September 24, 2018, 12:30:17 PM »

I agree that the best pilots usually win, and they are almost always flying conventional layouts. Wink
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Konrad
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« Reply #13 on: September 24, 2018, 12:33:35 PM »

I'm not confusing anything. To create the pitching force, a portion of the wing either has to lose lift completely, or create negative lift.
...
Are you looking at the bell curve distribution? Again I'm not sure what you are getting at. That high aspect ratio wing have advantages.
Here is a nice primer for model aeronatics.
https://www.mh-aerotools.de/airfoils/index.htm

If there is anything I've said that is false or in error please let me know.

All the best,
Konrad
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Konrad
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« Reply #14 on: September 24, 2018, 12:36:33 PM »

I agree that the best pilots usually win, and they are almost always flying conventional layouts. Wink
Yes, conventional layouts are very popular. Roll Eyes
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VictorY
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« Reply #15 on: September 24, 2018, 01:34:13 PM »

If after reading the section called "Basic Design of Flying Wing Models", you still believe huge compromises aren't being made in performance to create enough stablility for the flying wing to be controllable, I don't know what to tell you. There are caveats like, "Sweep and twist usually cause a performance loss, which can be minimized, by choosing airfoils with moment coefficients cm c/4 close to zero." But they don't really explain a lot in regards to how those modified sections compare to conventional foils. Compare the drag polars of these vastly different airfoils and it should give you the same conclusion as the author's statement about sweep and twist. They all cause performance loss, the sum of such losses which cannot be overcome by the deletion of a small but effiecient group of tail feathers.

So you've got wing area, wing sweep, wing twist and/or reflexed airfoils all working against you. It's a compromise that just doesn't allow flying wings to compete in the real world. Let's not even talk about stalls heaven forbid. LOL

Have fun though. It looks like a fun javelin style hand launch or light slope with friendly landing site plane.

Cheers
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Konrad
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« Reply #16 on: September 24, 2018, 02:28:18 PM »

That looks interesting Konrad. I'm curious to see how it performs. DSA tubes - I checked out the links on the hyper light site and have a vague idea of what they are supposed to do. My German is just not good enough Smiley

I've never seen a wing launch as well as that on a bungee - but it does have a low wing loading.

John
I too have always been attracted to the “Flying Wing” despite her idiosyncrasies. Like having a lighter wing loading but still can’t launch as high off a winch. Way back in the late 80’s I had a Klingberg 100 wing. Loved that she had flaps and a variable center of gravity. But my Sagitta 100 would out fly her at most TD contests. Mainly because of the performance on the winch. But from any given altitude and in the same air the Klingberg 100 wing flew better than the Sagitta, again as a result of the lighter wing loading and lower drag.

The RES-DART should be a lot of fun. Not sure how the DSA tubes will actually work. I’m concerned with the Reynolds number working against the airflow inside those tubes. Like is there any flow on that inboard wing tip?

I recall the Horten brothers mentioning middle effect with raked back wings. I wonder if the RES-Dart fuselage addresses this. Or should I add a classic Horten center section stinger?
In my response to John, I think the term idiosyncrasy covered all that. I even go into the poor performance on the winch. John and I are both impressed at how the RES-DART is climbing on the low powered (approx. 8lb) high start.
As to turning performance that video is showing how little energy the RES-Dart looses in a turn as demonstrated by the level figure 8’s. (Much less than the conventional model it was fly with that day) The video also shows how little altitude loss there is from a full deep stall (less than a wingspan). That video was made to address all the idiosyncrasy guys like you and I have concerns about.

Now I’ve said I hate the yaw skid needed to induce a roll with the classic RES configuration. I’ve spent a life time trying to learn not to fly my models in a skid! The RES-Dart  should address this concern and fit MY style of flying. Another thing I have an issue with is picking out my model from the gaggle of others when I’m high coring out a thermal. The fact that the RES-Dart has more surface area than even the Chrysalis-lite is a nice plus when it comes to visibility, up high. Also that the plan form is very different is another big help for those of us (me) that have to fly line of sight.

I said even back when, my antiquated Sagitta 900 would beat my much more modern Klingberg 100 wing in a TD contest.

So again I’m not sure what your issues are with my possision(s) or that of the RES-Dart.

I'd like to ask if you have anything constructive to add, such as how the fuselge center fairing might be built (designed) to blend in with the AG35 airfoil? Would it add any benefit over the small fuselage stinger already there?

All the best,
Konrad
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« Reply #17 on: September 24, 2018, 03:46:37 PM »

Nothing to offer in that very specific area of design other than to say the designer seemed to have done a pretty good job. I'd go RDS on the control surface linkages before worrying about drag on the fuse.
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Konrad
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« Reply #18 on: September 24, 2018, 04:48:12 PM »

That’s a good point.
In case anybody is following along the improper implementation of control linkages can result in substantial drag. So much so, as to be equivalent to the drag that was lost getting rid of the stabilizer.
https://www.mh-aerotools.de/airfoils/index.htm
See Aerodynamics and then Drag of Aileron & Flap Linkages
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Hank G B Z
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« Reply #19 on: October 01, 2018, 03:07:16 PM »

Hey Konrad,

Signing on for the build log.  Looks like a neat model.  Are you building the motor glider version.  I know you like motor gliders so i'm just curious. 

Hank
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Konrad
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« Reply #20 on: October 02, 2018, 01:21:07 PM »

Hank, I have a lot of 2 meter ships, ranging from the light Pulsar type to Hotliner models, with the winch on board. As you know I think this is the closest we have come to making a true soaring machine. As the winch is kind of like vultures, eagles or hawks leaving their legs on the ground after hopping into the air. Not cool!!

This RES-Dart will be to the “standard" F3-RES spec, as I’m not aware of any formalized F3-REST rules (“T” being throttle).
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