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Author Topic: Chrysalis F3-RES, DJAerotech I'll be improving it until it doesn't work  (Read 7761 times)
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OZPAF
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« Reply #200 on: August 03, 2019, 05:35:56 AM »

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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.

I agree. However the class is well established now.

Quote
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.

I fly a 2.9m F5J model - the "Inside" which with it's low weight of 1100g only has a wing loading of around 4.5oz/ft2. https://www.hoelleinshop.com/Planes-Helicopters-Quadcopters/Planes/Hoellein-CNC-planes/INSIDE-F5J-low-priced-starter-model-for-F5J-2866mm.htm?shop=hoellein_e&SessionId=&a=article&ProdNr=GRU2016&t=49301&c=171&p=171

 I fly in winds up to 8-10mph and have never added ballast. It has a Drela AG35 - quite thin and the penetration is surprising (this is without using reflex ). I think the modern RES models would have a fair speed range. Flaps though would be a great idea.

John
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VictorY
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« Reply #201 on: August 03, 2019, 08:21:21 AM »

8-10 is considered low wind, a gentle breeze according to the Beaufort scale. I didn't ballast my AVA RES in those types of conditions either. My statement was regarding higher wind conditions that would require the high cruise speeds associated with flying in stronger conditions, say 5 or more on the scale, where a morphing airfoil along the span of the wing becomes much more effective. That plane was so good it was almost boring to fly it on any day with decent conditions. Ballasted, it could still hold it's own in 15-20 mph winds, but you were definitely wanting to reach for the flight mode switch when caught too far downwind. LOL  Grin

Hoping to build a Skybench Sky Bird when they start production again. That series of woodies are some of the best flying kit built RES planes ever designed. RIP Ray.
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Konrad
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« Reply #202 on: August 03, 2019, 09:16:58 AM »

Quote
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.

I agree. However the class is well established now.

Quote
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.

I fly a 2.9m F5J model - the "Inside" which with it's low weight of 1100g only has a wing loading of around 4.5oz/ft2. https://www.hoelleinshop.com/Planes-Helicopters-Quadcopters/Planes/Hoellein-CNC-planes/INSIDE-F5J-low-priced-starter-model-for-F5J-2866mm.htm?shop=hoellein_e&SessionId=&a=article&ProdNr=GRU2016&t=49301&c=171&p=171

 I fly in winds up to 8-10mph and have never added ballast. It has a Drela AG35 - quite thin and the penetration is surprising (this is without using reflex ). I think the modern RES models would have a fair speed range. Flaps though would be a great idea.

John
John we are in full agreement! That is why I made this statement. (Sorry for the improper spelling. Thank the Gods this isn't an english literature forum!  Grin )
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 accepted standard of competition. But that doesn’t mean I'm blind to its short comings.
I'm at a loss as to why we had 3 pages of debate claiming that spoilers are superior. Yes, they work that wasn't the point. It is just that they have a performance penalty and if looked at with modern airfoil code there are control option that offer so much more for the same complexity. I'm not nor have I ever wanted to do away with the F3-RES class. I just made the statement that I hate Spoilers. I tried to give folks reference material to support my position.

Now I'm at a loss as to why a valued member of HIP came into this thread with an agenda against what was obviously my attempt at being humorous with my statement: "I'll be improving it until it doesn't work". This was my admission that making any improvements to the Don Stackhouse design was fraught with perils. I think one of the real improvements was the drag link.

I also made a statement that the drag link was a superior means to control that awful spoiler. I also made some statements in support of that claim. I'm really thankful for Lincoln making his well thought out and supported arguments in favor of springs and magnets.  

The new airfoils really have opened up the skys. I just restored a 40 year old Oly II. I just couldn't stand it, and had to move the spoilers aft about 2"off the main spar. And yes I used the drag link not the pull cord to control them. While I love the old gal she is a pig with that wing planform and that gross high cambered flat bottom airfoil. I have 5 much smaller 1.5 to 2 meter Simply the Best and Pulsars that just simply out fly her.

I too love a well made woodie. I also love the glass slippers. They each have their own esthetic appeal. But when it comes to flight performance, the freedom afforded in design with composites is undeniable.



All the best,
Konrad

Edit: For format and spelling errors
« Last Edit: August 03, 2019, 10:36:08 AM by Konrad » Logged

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Konrad
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« Reply #203 on: September 05, 2019, 10:19:32 AM »

I’m seeing the Chrysalis Lite F3-RES all but gone from the contest flying scene.

I’m sorry to see this as I liked how responsive the Chrysalis Lite F3-RES is to signaling lift and how tight she will core a thermal. The only knock I really had against the Chrysalis Lite F3-RES  was that she trims a bit heavy. She builds light enough but to get the balance I like I had to add a lot of nose weight.  This presented a problem in that it appeared that my launches were not as high as others. If one can get the AUW down to less than 400 grams, I feel the Chrysalis Lite F3-RES will actually out fly any current F3-RES ship. Truth be told that with my thermal skills the 50 grams of overweight really isn’t the limiting issue.

Talking with folks at the field most think the Chrysalis Lite F3-RES  has a flutter issue. I haven’t seen this. There was talk that at high altitudes the stab goes into flutter a lot easier than at low altitude. I have to admit I don’t understand how the air density would effect the flutter point. Does the thicker air dampen the structure’s response? I’d have thought that the thicker air would allow for greater forces acting on the surfaces driving the structure into flutter earlier.

Anybody have a reference I could read explaining how altitude density effects the flutter response of a structure?

All the best,
Konrad
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OZPAF
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« Reply #204 on: September 05, 2019, 07:44:52 PM »

How high are they flying? I wouldn't imagine that there is sufficient density change at a altitude of say 400-600' to affect anything as the density in the Standard Atmosphere at 5,000' is 86% of that at sea level.

Strange. If flutter was a problem then I would have imagined that you may have come across while penetrating on windy days for example.

Have fun.

John

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Konrad
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« Reply #205 on: September 05, 2019, 09:45:05 PM »

The USA high plains desert (Denver, Los Alamos) 6K to 7K feet. 

I would have thought that over spec'ing a launch at 10 lbs even a sea level would put the structure in flutter, if it was to flutter. 

Like I said I don't understand the claim. That is why I'm looking for some reference material.

All the best,
Konrad

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Konrad
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« Reply #206 on: September 11, 2019, 09:53:20 AM »

I just learned that Don Stackhouse was claiming that altitude had an effect on flutter speed. He is saying that flutter is related to true airspeed, not indicated airspeed. (I have to admit I’m not following this) This may be where the comments I heard on the field are coming from.

I know Don and Joe made a point that the linkage needs to be tight. I wonder if a lot of this tail flutter is a result of the hinging and the rather short tail control horns. I wonder if bringing the control rods up through the boom at some point along the stabilizer span would allow for longer control horns. I’d think the stab being glued to the boom in this area would offer support for any loss of strength the holes presented. If boom strength was a concern, maybe wrap the area adjacent to the holes with fine kevlar thread to brace the carbon fibers of the tail boom around these holes.

All the best,
Konrad
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