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Author Topic: Chrysalis F3-RES, DJAerotech I'll be improving it until it doesn't work  (Read 4943 times)
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Konrad
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« Reply #100 on: September 05, 2018, 12:48:52 PM »

LOL,
We need to define "high speed pass". How does anything above 2 time the stall speed sound?

Yep, I even had a DJAerotech Monarch HLG with "moving" trailing edges. It was because of the innovative things I saw in that design that I went with another Stackhouse design this time around, the Chrysalis-lite. For the Chrysalis-lite I liked the sag compensated profiles and proper application of carbon in the spar. I also liked the flat fuselage.

Spoilers to my mind destroy the wing wether they are attached to an RES or added to full house wing. Heck, even wether they are deployed of retracted. I'm not aware of there being different forces on the spoilers needing different control or actuation systems for RES or full house ships..

Now that is something I haven't done, Scale Gliders. I liked that you have a self launch in the nose of that ship. That small prop looks to drag her up just fine.

So I have to ask do you prefer the RES ship to the full house ship? Other than programing the radio I much prefer a glider with a fully articulated TE.

« Last Edit: September 05, 2018, 01:00:10 PM by Konrad » Logged

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« Reply #101 on: September 05, 2018, 01:39:08 PM »


So I have to ask do you prefer the RES ship to the full house ship? Other than programing the radio I much prefer a glider with a fully articulated TE.



Depends on my mood. I'm getting into freeflight lately too, which is why I ran across this thread. Not too many rc guys hanging out here.
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Konrad
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« Reply #102 on: September 05, 2018, 01:43:41 PM »


So I have to ask do you prefer the RES ship to the full house ship? Other than programing the radio I much prefer a glider with a fully articulated TE.



Depends on my mood. I'm getting into freeflight lately too, which is why I ran across this thread. Not too many rc guys hanging out here.
It is a shame. But for those of us here, it is nice to have a place to discuss and learn without the forces from vendors or the ad dollars trying to manipulate the discussion.

All the best,
Konrad
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dosco
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« Reply #103 on: September 06, 2018, 07:53:43 AM »

Spoilers to my mind destroy the wing wether they are attached to an RES or added to full house wing. Heck, even wether they are deployed of retracted. I'm not aware of there being different forces on the spoilers needing different control or actuation systems for RES or full house ships..

For those of us who are curious ( ... me ...) could you explain what you don't like about spoilers?

-Dave
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Konrad
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« Reply #104 on: September 06, 2018, 10:32:39 AM »

To paraphrase our constitution; We hold these truths self evident...

Spoiler as they are installed on most RES and ship in general are placed on a hyper critical area of the airfoil. They disrupt the airflow over the wing even when closed.  That is rigging and construction issues make it difficult to keep the profile as designed.  Then there is the flow problem of high pressure air (from the fuselage) spilling out on to the wing from the gaps.

If adding the 3rd channel, one should add bottom hinged ailerons rather than a spoiler as they allow for much better control and overall thermalling efficiency.  The slip angle of the fuselage coring out a thermal can be controlled (cross controls). With the cost of todays radios I see no reason not to have 4 to 7 channel ships. Adding a second aileron servo allows for the aileron to function as lift control devices, with none of the issues associated with "spoilers".

The RES ship is a throw back to 60’s when radios and servos were very expensive and often inoperable. To my mind flying a RES ship in the 21st century is a kin to flying a biplane as a glider. But if all contestants are crippled by the same requirements the F3-RES class can be a very enjoyable low cost activity.

All the best,
Konrad
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dosco
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« Reply #105 on: September 06, 2018, 11:02:00 AM »

To paraphrase our constitution; We hold these truths self evident...

Spoiler as they are installed on most RES and ship in general are placed on a hyper critical area of the airfoil. They disrupt the airflow over the wing even when closed.

So ... why not place them a bit further back?

Or does that still violate your sensibilities?

Regards-
Dave

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Konrad
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« Reply #106 on: September 06, 2018, 11:09:20 AM »

That helps a bit, but still disrupts air flow over the wing. How the separation bubble responds would be rather difficult to predict. It is best to avoid the issue altogether.

Why not add ailerons via two servos? One gets far more control, both as to set up (differential) and flight. Why cripple ones self with a spoiler?

All the best,
Konrad
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VictorY
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« Reply #107 on: September 06, 2018, 04:25:23 PM »

If your spoilers are causing you issues with airfoil fidelity or leaking air from gaps in the fuse to gaps in the spoiler bay, you need to improve your modeling skills. LMAO You can build spoilers that operate just as efficiently as those on full scale aircraft, even if you use linkages. Smiley  How many full scale gliders DON'T have spoilers???

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VictorY
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« Reply #108 on: September 06, 2018, 04:36:01 PM »

Here's the way I look at it if concerned with efficiency. Is it easier to build a servo bay properly, negating the few concerns you have about spoilers when in the closed position? Or is it easier to teach someone all the knowledge that would be necessary to cleanly and accurately install bottom hinged flaps with wipers, top hinged ailerons with wipers, and the ins and outs of programming as well as how to execute that programming in flight, all in a manner that improves performance above that of the nearly perfectly designed modern RES? I think not. Just my opinion though. I've seen too many pilots who weren't already well seasoned, struggling with making a full house glider perform as well as a RES in real life.
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Konrad
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« Reply #109 on: September 07, 2018, 11:17:43 AM »

...I've seen too many pilots who weren't already well seasoned, struggling with making a full house glider perform as well as a RES in real life.
So true, RES is an entry level event. But I think the REF is a far better configuration even for the begineer. A full house ship should not be a struggle. With proper programing arcitecture they should be a joy to behold.

If your spoilers are causing you issues with airfoil fidelity or leaking air from gaps in the fuse to gaps in the spoiler bay, you need to improve your modeling skills. LMAO You can build spoilers that operate just as efficiently as those on full scale aircraft, even if you use linkages. Smiley  How many full scale gliders DON'T have spoilers???
LOL.

There may be some truth in that! As an aerospace machinist I routinely had to work with tolerances out to 5 decimal places. When working with balsa I claim I can hold a tolerance of 0.01” (0.25mm) but often more like 0.005 (0.15mm). At these tolerances the stability of the base material comes into play.

On full size aircraft they use much more sophisticated hinging and actuation. Also the spoiler or spoiler box is sealed. But as you know there is little correlation between our models and the full size man carrying aircraft.

Now here is how a proper glider control surface should look. A live fully sealed hinge, with contour maintaining wiper. And the real key its aft placement on the airfoil. This keeps us from flirting with the separation bubble!
This is easily done even in balsa.

Your point about struggling with a full house ship, is more a condemnation of software than aircraft configuration. As to programing I too find the master/slave concept very difficult to implement. But the object based programing found on Multiplex radio since the Profi and now what we have with OpenTX, make extracting the most from our gliders child's play. And templets from the likes of Mike Shellim make this even easier.
http://rc-soar.com

You might have noticed that unless the designer is restricted by the rules to use spoilers, given a choice most will opt to use a flap rather than a spoiler if restricted to 3 channels. Hence the rise in the REF (Rudder Elevator Flap) type model. These really do fly better that RES ships.

Now back to the crippling device found on the F3-RES, commonly known as a spoiler. Even with the Konrad's add improvement to the Chrysilas-Lite, of spoiler stops at both ends of the spoiler bay. I can’t keep the flexible spoiler within 0.010” of the designed profile across the whole span. I’ve tried covering the back side of the spoiler to add some rigidity and to control the moister distortion of the spoiler. But these fixes really have only been mediocre at best, as the spoiler concept is inherently flawed.

All the best,
Konrad




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Re: Chrysalis F3-RES, DJAerotech I'll be improving it until it doesn't work
Re: Chrysalis F3-RES, DJAerotech I'll be improving it until it doesn't work
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VictorY
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« Reply #110 on: September 07, 2018, 01:28:06 PM »

Alrighty then! Enjoy your fantasy.
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Konrad
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« Reply #111 on: September 07, 2018, 02:33:33 PM »

And those would be? That positive action controls are desired over free floating. That any glider configuration (Full House or REF) is preferable to an RES ship. Or that I can hold the size on a balsa part to .25mm of nominal. Roll Eyes

Now I’ve seen a few pod and boom model suffer the loss of their tail as the tail snags on objects on the ground. To address this DJAerotech would like one to add a fillet blending the boom into the LE of the V tail. Far too many folk omit this in an effort to save weight. (Remember that every gram in the tail will take a bit over 3 grams in the nose to balance out). This is weight well worth spending, as a broken tail will in all likelihood cost more in repair weight than the fillet in the first place.  

My fillet (fairing) is made from a very dry micro-balloon and epoxy mixture that was shaped to have a convex profile with a wet finger. I find that this sheds the insult and trauma of landing a bit better than the concave style shown on the plans.

All the best,
Konrad
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Konrad
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« Reply #112 on: September 10, 2018, 05:58:24 PM »

I’m starting to feel like I’m under a time crunch, as I’m coming up on the year anniversary for this build! Undecided I thought this build would only have taken me two to four weeks.  Shocked

Well the decades since I last built an RES ship have not yielded a process that allows a spoiler made for TE stock to actually fit the airfoil. Cry After spending about two hours twisting and preloading the spoiler the best fit I can get is with in about 0.3mm of profile. Now if you listen to some aerodynamicists these error will all but guarantee that the wing will not fly!  Roll Eyes I’m actually thinking that for the RES class this discontinuity of the airfoil near the root is done on purpose, as it will build in aerodynamic wash out, forcing the center section to stall before the tips. Grin

To keep the Leading Edge (LE) of the spoiler in place I had to resort to using double sided tape in three places, at the tips and near the servo. This tape keeps the LE spoiler from riding up above the wing acting as a turbulator.
To get as good a fit as I have I have to manually push down the spoiler in position. Once popped open the spoiler will not close near as well as the 0.3mm would lead one to think. I’m thinking if this is a problem that the removal of the spoiler stops near the center of the spoiler will allow me to over drive the spoiler closed for half a second then unload the servo to somewhere near being in profile. My Multiplex Profi, and Open TX radios allow this timed function.

All the best,
Konrad
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dosco
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« Reply #113 on: September 10, 2018, 10:35:51 PM »

Now if you listen to some aerodynamicists these error will all but guarantee that the wing will not fly!

Aerodynamicists are notorious for demanding perfection and not understanding how things are really made. I generally take what they say with a measure of jaundiced skepticism.

Except, of course, those few that actually building things. Al Bowers and Mark Drela come to mind.

-Dave
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Konrad
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« Reply #114 on: September 10, 2018, 10:50:52 PM »

Now if you listen to some aerodynamicists these error will all but guarantee that the wing will not fly!

Aerodynamicists are notorious for demanding perfection and not understanding how things are really made. I generally take what they say with a measure of jaundiced skepticism.

Except, of course, those few that actually building things. Al Bowers and Mark Drela come to mind.

-Dave

We real modelers are also notorious for demanding perfection! Have you seen the surface finishes on the latest carbon sailplanes? Or more to the point the performance from these works of art?  Now to be fair the wind tunnel does hold out that the flow is highly dependent on the shape of the object. Now the real world guy know to make a profile that has "adequate performance' from, forms (profiles) that are manufacturable and maintainable in the real world.  Mark Drela's work is impeccable!

All the best,
Konrad
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Konrad
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« Reply #115 on: September 13, 2018, 11:33:50 AM »

I have to admit that I have a love/hate relationship with taped hinges. I love the ease with which they are applied and that they seal the hinge line. I hate that they often move out of alignment!

The method I used on the spoiler to help keep the hinge in alignment is show in the cartoons. While I used double sided tape many folks will make an equivalent material by sticking some tape sticky side to sticky sticky side. If doing this you don’t need to add the mask to the in the spoiler pocket (Green line in the top cartoon).

I start by bringing the film covering into the spoiler pocket (Blue line). This adds a lot of surface contact for the covering as the taped hinge really is reliant on the bond of the covering to the structure.

I then put a piece of double sided tape (Red) on the top of the Spoiler and attach the other end to the film covered shear web that makes the front side of the spoiler box. This double sided tape will keep the spoiler, when closed, from migrating up in the airstream destroying the airflow over the wing. Now to keep the double sided tape from sticking to the LE of the spoiler I mask the unused side of the double sided tape with a piece of single sided tape. (Some folks will contaminate this area of the double sided tape with talcum powder).

I then fold down the spoiler and apply the full span tape hinge (second green line in the botton cartoon) per the manual, making sure that the double sided tape on top of the spoiler is fully encapsulated.

All the best,
Konrad

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« Reply #116 on: November 07, 2018, 11:58:20 AM »

Started test flying this Chrysalis Lite.  I need to say up front that she is a bit over weight at 414 grams!  I was hoping to be south of 400 grams even with the use of Oracover lite. What shocked me was that I needed over 35 grams of lead in the nose to reach my balance point of 87mm.

While I only have two or three test flight on her I’m really liking the control response from the V tail. Don Stackhouse has done a fantastic job with the design of the V-tail and matching it to the low aspect ratio wing. With only 3 flight I still have a lot of work left to do matching the V-tail differential and spoiler elevator mix and CofG trim.

Still haven’t put her up on a high start. But I did not see any flutter doing my dive tests.

Now I did suffer a failure in that I think I over sanded the fuselage corners. In coming to a stop on the slope, I did split the lower corners along the front of the fuselage pod.

I’ve stripped the fuselage and repaired the split. I also added 0.5 glass and finishing epoxy to the front 1/3 of the fuselage. This is to give some durability to the fuselage as I don’t fly off of sod farms. By my read of the rules this is still legal for most F3-RES rules. It is also hoped that the glass fibers might help keep the pod from splitting in the future. I decided to add this glass and epoxy as I had to add so much nose weight in the way of lead. That is I hope to trade some of this lead weigh for glass. I’m sure I’ll see a weight gain as the glass weight won’t have as great a moment arm as the lead weight.

I hope to have her repaired and the programing fine tuned enough to do more test flying by the end of the week.
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Hank G B Z
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« Reply #117 on: November 07, 2018, 07:18:48 PM »

Konrad,

  Glad to hear you got the Chrysalis assembled and flying.  Looking forward to the trimming process and to see how she does in a contest.  Any pics fo the assembled model?

Hank
 
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Konrad
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« Reply #118 on: November 08, 2018, 01:00:17 PM »

LOL,
The internet mantra, Pics or it didn’t happen!

Yes, I have a few pics. I have these in process photo. These where taken about a month ago. I have to admit I haven’t taken too many photos since HIP has had these provider change over issues. Also as result of the election cycle (in the USA) I’ve been active in canvasing for issues close to my heart rather than documenting my work.

I’d like to show that I’ve faced the hatch and front battery opening with 1/64 plywood. This helps greatly with the durability for keeping the part line crisp during the life of the model. You might see that I have added a 5° clearance rake to the rear part of the hatch. This is to allow the hypotenuse  of the hatch (diagonal line from the front top to the rear bottom) to clear the opening as the rear of the hatch is pushed up when opening the hatch.

I’ve also mounted the control horns a bit higher above the hinge line. This was done to get an effectively longer control horn. I like to use long control horns and short servo arms to aid in getting the most servo resolution. I make every effort to set up my servo to use 100% to 120% of the servo rotation.

An esthetic issue has always been how does one get the transparent color to blend into an opaque color. In this case most of this transition is done under the wing between the fuse and the bottom of the wing. Now there is a small area at the rear of the pod that you can see from the top. On the top of this rear fairing I covered with UltraCoat light transparent red #996 just like the wing. The rest of the fuselage is covered with ParkLight true Red #815. These two colors really are the same other than their opacity. Making a fine straight part line on the corner of the fairing starting from the trailing edge of the wing makes is very hard to tell where the transparent red of the wings stop and opaque red of the fuselage starts. UltraCoat is real good about this kind of color transition unfortunately it isn’t well documented. So you will need to go to your local well stocked hobby shop and color match your own rolls. In my case it is J&M Hobby House in San Carlos.
https://www.facebook.com/pages/j-and-m-Hobby-House/152996724710609

Maybe by the end of the night I’ll have photos of the fully repaired Chrysalis Lite repaired for flight, maybe even some in flight shot at Mussel Rock (AKA the Dump).

I’m loath to fly her off a high start as I don’t have an F3RES legal high start, nor do I have a fish scale to measure 4 KG of pull.
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« Reply #119 on: November 08, 2018, 02:28:21 PM »

Hey Konrad,

     the Chrysalis looks great.  I like the transparent red.  Again for some reason i thought this was going to be a motor glider, no sure where i got that idea.  I didn't mean to say i didn't believe you that the model wasn't finished with out pics, i was generally curious to see what it looks like.  Now to convince you to come down here so we can go fly together...

Hank
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« Reply #120 on: November 08, 2018, 04:08:48 PM »

Hank, I know you weren’t doubting the completion. But I find it odd that on the internet pictures seem to hold far too much weight than they should otherwise.

As it looks like the wind is coming off shore I don’t think I’ll be flying the Chrysalis lite today. I should just suck it up and finish reinstalling the radio.

I just piled all the components on the scale and am shocked that it looks like I lost 4 grams with the addition of the glass and epoxy.

I didn't think I sanded that much off the fuselage during the repair, and I think I put all the parts on the scale. As odd as it is I can only think that the post cure heat treating* of the epoxy has driven off some moisture. But 4cc sounds highly unlikely.

When reassembling the model I recalled an issue I had with the cover plate. DJ Aerotech has the hole mis-marked for the tow hook.

A visit with a few long days of flying sounds great!

* I try to post cure most of my epoxy work. This is why I had removed the radio as part of the repair.

All the best,
Konrad
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« Reply #121 on: November 08, 2018, 05:43:20 PM »

That looks very nice Konrad - just waiting to get airborne. Good luck with it and thanks for the detailed coverage of the build.

John

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« Reply #122 on: November 09, 2018, 06:16:20 PM »

Thanks John.

Radio reinstalled.

And much to my surprise the AUW is now 402 grams ready for the next round of test flight. All I can think is that I had the butchers thumb on the scale when I got 414 grams for my test flight weight prior to the repair.

In placing the servo I had two concerns. The first was being able to remove the battery for charging and all around maintenance. Second was getting the servo weight as far forward as possible and still keep rigid push rods.
I was limited in my kit in that the yellow bowden tubes were only 36.5” long.  This proved not to be a problem as I really couldn’t move the servo any further forward. I did have some concerns that there was too much flex in the bowden tubes under the wing, so I added a support wall.

Now to start the iterative process of adjusting the programing (AKA test flight).

All the best,
Konrad
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« Reply #123 on: November 10, 2018, 11:05:28 PM »

I realize that this post is a bit premature but as HIP is having some issues with the servers I thought it best to post my initial impression about the flight characteristics. These comments are based at best maybe on 8 minutes of flight time. To this add, that I as a pilot don’t like RES ships. Also I was flying in very light slope lift. The only other aircraft that were having success in the air were DLGs and a Dream Flight Ahi.

With the preamble out of the way. My impression of the flight characteristics are that the Chrysalis lite is a great flying glider! The ability to respond to the rudder commands are impressive. I actually felt like I was in full control being able to place the Chrysalis lite pretty much where I want to in the landing approach. I also like how responsive the tail is to indicating lift. I can’t say much about how the wing tips were at indication lift, as flying on the slope one usually is fighting the crab flying cross wind on the face of the hill.

Ok, for the reasons we buy a glider the Chrysalis lite excels at these. Now to details about the glider. The big elephant in the room is Chrysalis lite has unfortunately has developed a bit of a reputation for flutter. I want to be very clear on this. The Chrysalis lite is a competition ship and has NOT been designed to be a sport beginner type model. As a competition ship her structure is well match to the flying rigors she is to see during an F3RES competition. For a ship that has 583 inches of area and weighs 400 grams she is fantastic. But needs to be flown within the flight envolope for which she was designed. NO HIGH SPEED FLIGHTS!

I can say that my model has not shown any flutter even in my high speed dive test. True, I’ve yet to put her up on a high start.

Now one of the many benefits to slope flying is that you can be inches away from the model and observe how the model (structure) is behaving at flight speeds. I was flying my Chrysalis lite  at a rather high air speed staying  over one spot on the ground and noticed that the tail was was moving around a lot in the light turbulence. This boom flex is what I now think is the root cause for a lot of flutter reports.

In post #19 & 20 where I had an issue with the tail boom I talked to Don Stackhouse. He indicated way back then that DJ Aerotech had a larger, stiffer, lighter tail boom in the works. But that he had some concerns about the OEM being able to maintain the dimensions and that it would add to the cost of the model. While I think the interim fix of the new balsa tail with diagonal stiffeners is a move in the right direction. I don’t think is addressing the root cause of the flutter failures.

I realize that DJ Aerotech has to deal with  market pressure (price) when bringing a product to market. But I think not moving to the larger diameter tail boom is penny wise and dollar foolish. I know I’d be willing to pat $200 for Chrysalis lite that had a larger diameter tail boom a diagonally braced balsa tail and a longer nose for the fuselage pod.

The latter issue the short fuselage pod has been a thorn in my side. I really hated to add 22 grams of lead to the nose particularly when I was using a 2 cell LiFe 900 mAh battery. I’d like to see DJ Aerotech add 60mm 70mm maybe even more to the nose of the pod. Along with making the nose longer DJ Aerotech would need to make the fuselage a bit taller to accommodate the larger diameter tail boom. I’d like to see this 3mm to 4mm of height carried along the whole fuselage pod. This would add some geometric strength to the fuselage side (less flex to fail the fuse corners).  As this wetted area might interfere with the great rudder power the Chrysalis lite already has this might allow one use the full length of the as shipped tail boom.

I’d also like to see DJ Aerotech include longer nyrods I think as it is withthe 36' nyrods, far too many folks are setting up the push rods without enough support of the carbon push rods near the servos. This is another likely cause for the poor flutter reports! Supplying 48” nyrods would allow for the longer nose and longer tail boom and allow for the servos to be place further forward than is currently allowed.

I don’t have the empty balsa sheets but I think most of the fuselage pod modification can be done without adding to the cost of the kit. Adding longer Nyrods and a larger diameter tail boom would add to the cost but it would be so worth it! It would address the main issue I’ve heard as to why guys are going to the smaller Yellow Jacket RES, and that is flutter. Please Don and Joe you really have a nice competitive RES ship. We just need to see more of them on the flight line, actually going up the line!

All the best,
Konrad
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Cut it twice and it's still too short!
Konrad
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« Reply #124 on: November 13, 2018, 05:17:46 PM »

Just got back from 3 hours of flat land work. This was all done from a hand launch.

The best set up I’ve come up with is as follows,
All up weight 418 grams with the CofG at 88mm to 89mm ( 30 grams in the nose as dead weight).
Elevator 16mm up, 17.5mm down
Rudder 26mm with 1.5mm more down differential
Spoiler comp. 8mm

I’m a bit disappointed in the AUW weight of 418 g (14.75oz). The Chrysalis lite really needs a longer nose pod! 30 grams of dead weight is ridiculous for this kind of model.

I did like how she signals lift. At 89mm CofG she really gets on step in lift. By the same token she all but stops in sink when the tail starts to hang down. The broad chord wings also signaled well. She can core well, but I have to admit I was having issues with trying to use the left hand to control the circle. (Like I said I don’t like RES ships, this will take some time to over come).

The spoiler was easy to set up to have little or no attitude change as it was deployed.

As to low speed V-tails, this is the best I’ve flown.

I have to say that I could not notice any performance difference between the wings from as cut airfoil side and the side I repaired from my building error.

I really like the wing. I’m thinking for next years build of ordering a wing and stabilizer and cutting my own long nosed fuselage. Heck, on this one I might even hack off the pod and build a long nose pod for her.
This Year I’m building the RES Dart. But by next year I hope DJ Aerotech will have upgraded the kit to have a longer nose and stiffer boom. She has the potential to be the best handling and flying F3RES ship out there.

All the best,
Konrad
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Cut it twice and it's still too short!
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