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Author Topic: Chrysalis F3-RES, DJAerotech I'll be improving it until it doesn't work  (Read 8827 times)
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Konrad
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« Reply #175 on: July 29, 2019, 11:15:37 AM »

After having broken a push rod on my Chrysalis Lite F3-RES. I’m using this as an excuse to replace the 2017 V tail with the lighter 2018 V tail. I have to admit I had some concerns about de-bonding the V tail from the carbon tail boom. As the boom is also made from epoxy, I feared that the heat needed to break the glue bond would also damage the epoxy in the boom's carbon matrix. With the use of aluminum foil as a heat shield I was able to remove the old V tail with little or not problem. Much to my surprise I was also able to save the V tail for use in some other “Frankenstein" glider later on.

Looking at the tail boom I see where I had left some unneeded weight. These tail booms are spiral wrapped. This results in there being a nice spiral epoxy ridge on the outside of the boom. In “composite school” I recall that the epoxy matrix that is not binding fibers is offering very little strength to the lay up. So with the tail off I have sanded the tail boom with 220 grit sandpaper to remove most of this spiral. I sand the boom until I start to see flecks of black in the water. I want to remove as much epoxy as I can without cutting into the carbon fibers. On my boom this has saved about 0.7 grams off the tail boom.

Yes, the Chrysalis Lite F3-RES flies so nice as to warrant the rework of the tail. With luck I’ll be able to get below 400 grams while in proper trim (balance).

Now to build the light weight V tail.

All the best,
Konrad
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lincoln
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« Reply #176 on: July 29, 2019, 05:28:23 PM »

If your torsion bar was 4 inches long, I calculate that it provided around 0.44 in-lbs (7 in-oz) at 90 degrees deflection. If the spoiler was an inch wide, then that's equivalent to maybe 0.5 lbs from a magnet that's close to the edge of the spoiler. Or 0.88 lbs in the middle. It might stress the servos less to use a longer or thinner wire and bend the ends so that the initial deflection was 180 degrees. If the spoiler opens 90 degrees, then in the first case the servo would be fighting 0.88 in-lbs when fully open and 0.66 in the second case.

If I had magnets, I'd use a very light spring out of pessimism. I suppose one could work up some kind of in flight sensor to see if the spoiler was pulled open. Maybe conductive contact points, an LED, and fast, low passes at dusk? Or a dummy wing section held out the window of a car.  I guess those with telemetry in their radios might have an easier way.
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lincoln
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« Reply #177 on: July 29, 2019, 05:31:49 PM »

P.S. Don't take my calculations as absolute fact. I could have dropped a decimal point someplace. I probably should have done them 3 times or more, but I was lazy and I didn't.

Also, in-oz on the spoiler probably won't be the same as in-oz from the servo due to details of the linkage, throw, friction etc. It's possible to set up a linkage such that very little torque is required to hold the spoiler fully open.
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Konrad
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« Reply #178 on: July 29, 2019, 06:18:15 PM »

... Or a dummy wing section held out the window of a car.  I guess those with telemetry in their radios might have an easier way.
LOL,
Sounds like a Burt Rutan in the making.

All the best,
Konrad
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lincoln
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« Reply #179 on: July 30, 2019, 12:21:34 AM »

If you gave me a rejuvenation treatment and a stronger forebrain, maybe I'd be a Rutan in the making. As is, I spend way too much time in forums like this one.
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Konrad
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« Reply #180 on: July 30, 2019, 09:23:54 AM »

If you gave me a rejuvenation treatment and a stronger forebrain, maybe I'd be a Rutan in the making. As is, I spend way too much time in forums like this one.
You and me both! Shocked

In my case somebody would be working with very raw materials trying to bring me anywhere near that of Rutan.

All the best,
Konrad
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lincoln
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« Reply #181 on: July 30, 2019, 10:38:52 AM »

Come to think of it, I might need some "genius" added, whatever that is. Since they'd already be working on my brain, how hard could it be to add that as well?
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« Reply #182 on: July 31, 2019, 09:34:46 AM »

Interesting discussion on spoilers Konrad and Lincoln. In the 90's when I was flying F3B - BFB(before butterfly Smiley. The model I was flying used vertical blade spoilers. Set up carefully these sealed well and were much more effective than the rotating blade spoilers. They seemed to have a fairly linear response as well. However they were quickly dropped when butterfly came along!
I remember they were a right royal pain to get the throws right( on both panels) using a bellcrank with pivots to take the fork ends from the removable wing panels.
This a pic of my second LB-3 of around 1990 - excuse the poor picture quality.

John
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Konrad
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« Reply #183 on: July 31, 2019, 11:35:01 AM »

I might agree with much of what Lincoln said. That is that spoilers might be better than nothing. And in the old days they may have been the only practical way to add lift control devices to our gliders. But today I'm of the opinion that they are best left in the past.

I don't understand why the powers that be in this class F3-RES have chosen to force spoiler on us but they have. As such I've been forced to deal with them again. And it is my experience that the best way to set them up is with a positive mechanical link that controls the full range of actuation, both the opening and closing of the spoiler.

All the best,
Konrad
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« Reply #184 on: July 31, 2019, 05:00:59 PM »

Konrad

Would a trailing edge device like on a scale H101 Salto, but with increased length(spanwise) be a possible answer?
It would not interfere with the boundary layer at max camber point when closed.
It wouldn't have any disturbance to the air flow until near the TE and as it was not acting as a flap, would not break the rules on that point.
But would just give drag to help the landing phase for RES airframes and have no leakage of higher pressure air from underneath to the top of the wing as it could be completely sealed along its length.

Just thinking out aloud as it were.

John M
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VictorY
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« Reply #185 on: July 31, 2019, 05:43:58 PM »

Dr. Mark Drela, " Recessed is always safe." Wink
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Konrad
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« Reply #186 on: July 31, 2019, 06:11:26 PM »

Konrad

Would a trailing edge device like on a scale H101 Salto, but with increased length(spanwise) be a possible answer?
It would not interfere with the boundary layer at max camber point when closed.
It wouldn't have any disturbance to the air flow until near the TE and as it was not acting as a flap, would not break the rules on that point.
But would just give drag to help the landing phase for RES airframes and have no leakage of higher pressure air from underneath to the top of the wing as it could be completely sealed along its length.

Just thinking out aloud as it were.

John M
That would work real well. But the F3-RES rules are specific as to how far aft the "spoiler" can be. They are trying to outlaw that type of spoiler and flaps.

The F3-RES rules are trying to dictate a model that is simple to build and mimic what we flew in our youth. Think Wanderer but with a modern airfoil. Generally I think the rules are very successful. This is why I have 4 ship built or on the bench that meet that set of rules.

I think the spoiler found on Dr.Drela's Allegro is too far aft by most F3-RES rules.
http://www.charlesriverrc.org/articles/allegro2m/allegro.pdf

Dr. Mark Drela, " Recessed is always safe." Wink
Folks should stop quoting out of context. The rest of that statement from Dr. Drela reads;

"To be more specific, the step in the surface should be smaller than the boundary layer displacement thickness (delta-*) at that location if there is to be little or no penalty. The delta-* distribution can be easily calculated with Xfoil. The worst-case situation is at high speed, like a fast penetration glide, since delta-* will be the thinnest then. In general, the farther back on the chord, the less critical the fit. On my RES ships I put the spoiler as far back as the structure or the rules allow (within 2" of the TE). That way an ill-fitting spoiler is much less likely to cause problems. "

The key is less likely to cause problems . Not that it is safe to mess up the airfoil profile with bumps and valleys. Like I said move any disturbance aft. Like the hinge line for the flaps and ailerons. Spoilers have no place at or near the apex of the airfoil.

Please refer back to this post.
https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=22619.msg233266#msg233266
I'm sure some might find your input valuable, but not in this thread.
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« Reply #187 on: July 31, 2019, 09:51:36 PM »

So he obviously thinks they are suitable devices and easily accomplished by the average model builder.

"I don't understand why the powers that be in this class F3-RES have chosen to force spoiler on us but they have." Because Mark Drela and many, many other sailplane designers think it has little to no negative effects on RE controlled plane performance. If you can't climb out to a speck in an AVA from a 10ft high thermal generated by a gnat fart, you got bigger problems than spoilers causing loss of performance. It simply isn't an issue unless you make it one or simply don't have the basic building skills needed to make a high performance model. Most people showing up to contests, even local club contests don't seem to lack the building skills.
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Konrad
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« Reply #188 on: July 31, 2019, 10:54:12 PM »

So he obviously thinks they are suitable devices and easily accomplished by the average model builder.

"I don't understand why the powers that be in this class F3-RES have chosen to force spoiler on us but they have." Because Mark Drela and many, many other sailplane designers think it has little to no negative effects on RE controlled plane performance. If you can't climb out to a speck in an AVA from a 10ft high thermal generated by a gnat fart, you got bigger problems than spoilers causing loss of performance. It simply isn't an issue unless you make it one or simply don't have the basic building skills needed to make a high performance model. Most people showing up to contests, even local club contests don't seem to lack the building skills.
Nope that is why he recommends moving the spoilers to the back of the airfoil. They do negatively effect the airfoils performance. Moving the spoilers to the rear of the airfoil mitigates much of that problem. Wether the benefits in the landing zone out weighs the negative effects on the airfoils performance may make them desirable over not having them at all. But as a design study they are to be avoided if one is looking for the best performance from the airfoil/wing.

While I have no issues coring out thermals from hand launch altitudes, it is true I can't core out a gnats or gopher fart. While it is true there have been some disparaging remarks made about my flying skills, my builds have been universally acclaimed as some of the better ones.  This is why I can tell that spoilers are so detrimental to the performance of the sailplane. Crow is the much preferred method to control lift and drag.

Articulated trailing edges offer so much more in the way of flexibility and performance for the aircraft when it comes to tailoring it in-flight to a wide variety of conditions.  Now it does take more skill to fly and program a full house sailplane. So it is understood that it might not be the best option for an entry level event.  But those of us that have learned how to use the articulated trailing edges they are highly desirable over the performance robbing spoiler, particularly those called out by the F3-RES spec's. Those that have a numb left thumb, well spoilers might still be their best option. Actually a simple flap without aileron reflex would have made a better sailplane than the classic spoiler spec'd in the F3-RES rule book.

As an entry level event F3-RES is a simple class where the ability to read the lift is key, The simple type of equipment is also key in forcing the novice, even the expert, to learn to read the air rather than spend too much time tuning ones ship. With less controls there is less to tune.

The DJ Aerotech Chrysalis is one of the better designs out there, and for me a highlight is that it comes from an American kit cutter.  To show that I put my money where my mouth is I purchased a second DJ Aerotech Chrysalis along with an upgrade kit for the one I used for this thread. Give the design from a know world class RC sailplane design team a try. Not only are these guy competent as RC designer they are experienced aerospace engineers dealing with full size aircraft and their aerodynamic phenomenon.

All the best,
Konrad
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« Reply #189 on: August 01, 2019, 08:11:54 AM »

The fact that the planes can easily climb out in weak low level thermals is proof that there is nothing wrong with using spoilers in these models. You can pick at the topic all you want, but the real world performance negates any and all worries about them, which is why they are still used.
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Konrad
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« Reply #190 on: August 01, 2019, 10:32:20 AM »

The fact that the planes can easily climb out in weak low level thermals is proof that there is nothing wrong with using spoilers in these models. You can pick at the topic all you want, but the real world performance negates any and all worries about them, which is why they are still used.
That doesn't prove a thing. For proof you would have to have at test with two identical ships other than one being equipped with spoilers. I would put money on the simple non-spoilered ship as being the one that would out climb the one crippled with the spoiler, when working that gopher fart.

And that is the point. For the sport flier these lightly loaded ships perform real well. Heck even the old Wanderer and Gentle Lady could offer the sport pilot hours of enjoyment. But to a competition orientated flier the detrimental effect on the airflow over the wing of a spoiler is noticeable, even when retracted.  Much the same could be said for the hinge line with articulated trailing edges. But with these TE devices the wing can be tailored to fit the condition or demands improving the flight performance of the ship. The key is that spoiler are prone to disturbing airflow with the detrimental effect on the performance of the aircraft, while articulated TE will enhance the performance of the aircraft. This is assuming that one has developed the skills to use the TE surfaces.

If landing points weren’t awarded in the F3-RES competitions none of us would bother with their installation. (It is allowed in most F3-RES rules to remove, not use spoilers) If articulated TE were allowed we would all be using them! As they offer far more in the way of flexibility to maximize the performance of the ship in a wide variety of conditions. Spoiler just spoil the full potential of the aircraft!

Anyway this is about my prejudices, based on decades of experience, against the use of spoilers. Now I highly recommend that you start a thread and try to put forward a cohesive argument in favor of spoilers. Might I point to the posts by Lincoln on how to make such an argument. He makes some good points justifying not needing a direct link to control spoilers. Again this is counter to my experience. But I full respect his position as it was well made. Most of your points in this thread have been poorly executed. This is why I recommend that you start your own thread as it might allow you to collect your thought in a more cohesive fashion. I actually think you might have some valid input on the subject, we just haven't seen it as of yet.

I'll close by saying I hate spoiler!

All the best,
Konrad
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VictorY
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« Reply #191 on: August 01, 2019, 11:46:20 AM »

Lol. Facts dont need a couple of hundred words to make them valid, but unsupported opinions needs tons of tweaking and flowery language to make them seem relevant.
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« Reply #192 on: August 01, 2019, 12:43:54 PM »

Take landing gear on pylon racers. I could start a thread about how ridiculous it is to require them to be fixed and post about it for a couple of thousand words but why? Everyone has agreed that they are functional, dont subract substantially from overall performance and should remain as is.
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Konrad
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« Reply #193 on: August 01, 2019, 01:30:40 PM »

Lol. Facts dont need a couple of hundred words to make them valid, but unsupported opinions needs tons of tweaking and flowery language to make them seem relevant.
To those that don't understand the concepts, it does appear that one needs to use more than full references of accepted experts. In my case I point to the full text of Dr. Drela. You and I both know I could pull up papers that show any deviation in the profile will up set the prediction and negatively upset the prediction. But then I'd have to explain how to interpret the graphs and mathematic expressions. That is beyond the scope of what I want to do in a hobby forum. It looks too much like work!

You are fixated on the quantitive value and make the assertion that it won't "significantly effect the results". Now to quantify a statement I'd need a lot more data.(Unfortunately, or fortunately Don Stackhouse does not publish what he is using as an airfoil). But in wide general sweeping remarks the Spoiler is to be avoided if there are other options available. (The F3-RES don't allow for more efficient lift control devices)

Many maybe even you seem to think that the airfoil is not critical to the outcome of the design. To that end yes, a Clark Y airfoil can be used on a dynamic soaring glider. But the results on a measured course would be rather disappointing, particularly if comparing the Clark Y to the airfoils used by Spencer to break 500 mph.

Again I don't know what pylon classes you are looking at. But as you know that answer, with regards to retracting gear, has to do with where the drag curves cross.  I don't think the Unlimited Reno racers would want to run the course with their gear hanging out, even if the weight of the retraction mechanism was removed.

In high level competitions good enough, isn't good enough! The other guy will take your position that "X" is adequate and PROVE you wrong.

Flowery language? Other than a humorous attempt with the word FART to describe thermals (you and I have both used that term) I don't see where I have used flowery language. If I have I apologize to the HIP membership.

All the best,
Konrad
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« Reply #194 on: August 01, 2019, 01:35:17 PM »

Flowery language? Other than a humorous attempt with the word FART to describe thermals (you and I have both used that term) I don't see where I have used flowery language. If I have I apologize to the HIP membership.
That's ok; I've been itching to use the ignore button
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« Reply #195 on: August 01, 2019, 01:43:07 PM »

Flowery language? Other than a humorous attempt with the word FART to describe thermals (you and I have both used that term) I don't see where I have used flowery language. If I have I apologize to the HIP membership.
That's ok; I've been itching to use the ignore button
Sorry to see you go, but I understand.

All the best,
Konrad
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« Reply #196 on: August 01, 2019, 06:28:28 PM »

Lol. Facts dont need a couple of hundred words to make them valid, but unsupported opinions needs tons of tweaking and flowery language to make them seem relevant.
To those that don't understand the concepts, it does appear that one needs to use more than full references of accepted experts. In my case I point to the full text of Dr. Drela. You and I both know I could pull up papers that show any deviation in the profile will up set the prediction and negatively upset the prediction. But then I'd have to explain how to interpret the graphs and mathematic expressions. That is beyond the scope of what I want to do in a hobby forum. It looks too much like work!

You are fixated on the quantitive value and make the assertion that it won't "significantly effect the results". Now to quantify a statement I'd need a lot more data.(Unfortunately, or fortunately Don Stackhouse does not publish what he is using as an airfoil). But in wide general sweeping remarks the Spoiler is to be avoided if there are other options available. (The F3-RES don't allow for more efficient lift control devices)

Many maybe even you seem to think that the airfoil is not critical to the outcome of the design. To that end yes, a Clark Y airfoil can be used on a dynamic soaring glider. But the results on a measured course would be rather disappointing, particularly if comparing the Clark Y to the airfoils used by Spencer to break 500 mph.

Again I don't know what pylon classes you are looking at. But as you know that answer, with regards to retracting gear, has to do with where the drag curves cross.  I don't think the Unlimited Reno racers would want to run the course with their gear hanging out, even if the weight of the retraction mechanism was removed.

In high level competitions good enough, isn't good enough! The other guy will take your position that "X" is adequate and PROVE you wrong.

Flowery language? Other than a humorous attempt with the word FART to describe thermals (you and I have both used that term) I don't see where I have used flowery language. If I have I apologize to the HIP membership.

All the best,
Konrad


Ok, maybe word salad would be more appropriate?! As for high level competition, rules are rules, and every class has them. Those competing for the top of the heap in all the RES and F3-RES classes are perfectly happy with their spoiler equipped anti-gravity machines. I've never heard anyone complain about feeling the lack of performance since they are the best light air planes on the planet. Some open class TD guys even choose to use their RES airplanes in super light conditions because they outperform the full house spoilerless planes with full trailing edge control in extreme low lift conditions. I guess they are just stupid or something. Roll Eyes

Cheers!

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« Reply #197 on: August 01, 2019, 07:12:06 PM »


Ok, maybe word salad would be more appropriate?! As for high level competition, rules are rules, and every class has them. Those competing for the top of the heap in all the RES and F3-RES classes are perfectly happy with their spoiler equipped anti-gravity machines. I've never heard anyone complain about feeling the lack of performance since they are the best light air planes on the planet. Some open class TD guys even choose to use their RES airplanes in super light conditions because they outperform the full house spoilerless planes with full trailing edge control in extreme low lift conditions. I guess they are just stupid or something. Roll Eyes

Cheers!


I think we may have a reading comprehension problem. Where have I complained about the performance of the F3-RES ship. In fact I like the class enough to have purchased 4 model that meet the spec’s. Other than the FAI F3F class of sailplane I have more models of this class than any other spec’d sailplane.

And yes, in dead air the simple light gas bag with its spoiler might be the better weapon for competition. But that is a very limited condition not often seen in the real world.The weight of the servos to drive each surface does at up, particularly with these small TD with limited energy in the high start. Please don’t assign word or ideas to me that I haven’t said.
 
this limited energy is why the nose of the Chrysalis needs to be lengthen to get the weight out of the ship. This is why so many of the newer ships have longer noses. It is all about the energy.

What I have said, is that spoiler particularly those as spec’d in the F3-RES class have a performance penalty. I also think that a ship built to the current F3-RES spec’s but with flaps (F3-REF) rather than spoilers would be more enjoyable and actually have more thermal duration performance than the current F3-RES format. But I had no input in the formation of the F3-RES spec’s and as such I’m happy to compete to this well excepted standard of competition. But that doesn’t mean I blind to its short comings.

Why would you think that anybody who knows how to select their tools and adheres to a set of rules is stupid?

Please step back and really read what I have posted.

All the best,
Konrad
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« Reply #198 on: August 01, 2019, 07:49:54 PM »

Where have I complained about the performance of the F3-RES ship.

"What I have said, is that spoiler particularly those as spec’d in the F3-RES class have a performance penalty. "

"...best left in the past."

You also suggested that the spoilers were being forced on you. Doesn't sound very pleasant to me. But have fun if you are enjoying flying planes with them, instead of trying to use Drela's name to make your case against them. He clearly stated that required tolerances are relative to boundary layer thickness which is largely determined by speed. All RES planes are, by nature, relatively low speed aircraft. If the wind picks up enough to require full ballast, no one flying RES is going to have a very good day without some luck and a boat load of skill.
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« Reply #199 on: August 01, 2019, 09:23:33 PM »

Where have I complained about the performance of the F3-RES ship.

"What I have said, is that spoiler particularly those as spec’d in the F3-RES class have a performance penalty. "

"...best left in the past."

You also suggested that the spoilers were being forced on you. Doesn't sound very pleasant to me. But have fun if you are enjoying flying planes with them, instead of trying to use Drela's name to make your case against them. He clearly stated that required tolerances are relative to boundary layer thickness which is largely determined by speed. All RES planes are, by nature, relatively low speed aircraft. If the wind picks up enough to require full ballast, no one flying RES is going to have a very good day without some luck and a boat load of skill.
That is true I think that spoilers should be left in the past. I also think that when the F3-RES were formulated about 5 years ago, that flaps should have been spec'd not spoilers. Still keep the models simple (no six servo ships and the like) but use flaps as they are more flexible than spoilers.  So you are correct and I've made it painfully clear I HATE SPOILERS. But to extrapolate that I don't like the F3-RES class of ship is false. I really enjoy the F3-RES format.

What I have said is that the spoiler as spec'd in the F3-RES class have a performance penalty. Not that the class is lacking performance. Now I'm sure I and most would enjoy an F3-REF ship more than an F3-RES ship. I understand that with modern airfoils the powers that be wanted a way to dump lift. What I don't understand is why choose a device that I found on my Oly II with its high cambered flat bottom airfoils. Flaps would have integrated so much better with today's airfoils.  Like I said Spoilers should stay in the past, especially with the thin modern airfoil.

Like you said nobody is going to enjoy an RES ship in wind, well most won't.  I submit that most would prefer a flapped ship over a spoiler ship as there is a lot less height penalty covering ground searching for that elusive thermal. I don't know about you, but I rarely launch into a thermal in the time window allotted at contests. This then means I have to search for them. This is where skill comes in reading the air and the response of one's ship. Now flaps set up to reflex the airfoil, even if it is only for half the wing, allows one to cover the ground a lot more efficiently looking for that thermal. And once the thermal is found the airfoil can be cambered to maximize the climb coring the thermal. None of this can be said of spoilers.  The ability to go up wind with the flap reflexed is what gives the REF ship a much wider usable weather window.

To summarize I hate spoilers, I love the F3-RES competitions, I think flaps in place of spoiler would add a lot more to the flight envelope for the same complexity, I think that with the strong 4 gram servos that are now on the market a 6 servo 2 meter sailplane might be practical on an F3-RES hi start.

All the best,
Konrad
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