FinnSpeed

Here's some detail images of my build. Landing gear mounting with openings from chin cowl to fuselage. Canopy latch in front. IMO, this works quite well but was a small pain to install... Air vents under the fuselage - these should be sufficient! And finally tail area showing the rudder hinges and the lightened rearmost frame that seems to be different from earlier production.

I have still a lot to do: Motor mount, battery tray, rudder servo and some details here and there...

GVI

Is there any more detail available on the flight Setup and flight Impression.
Gerhard

FinnSpeed

I'd like to hear more reports as well. I will certainly give my impressions when I get my plane in the air but please remember that I'm not a world class pilot. Maybe I will give Lassi Nurila a try to get his opinion...

The plane must be pretty decent since Bert Delaere scored a 5th place just last weekend in F3A World Cup.

GVI

In the meantime i finished my evo 2.
4720g, CG 230mm. Now i am waiting for good Wether for First flight.

br gerhard

GVI

After my first flight. CG moved a little back 235mm. Rudder is very agil, take a little to trim the plane for straight flight.
Awesome flight attitudes. Now I can start with final adjustments.

FinnSpeed

Gerhard, thanks for the info! I assume you like to trim the plane so that it flies inverted with very little push? I met a couple of pilots with Spark Evo II's in the Nordic Championships during last week and they had the CG right at the back of the wing tube which is much more forward (202 mm to be exact). Thus I assume that the plane tolerates a wide range of CG.

Mine is almost ready to maiden - I just have to install the battery tray and check the CG. I'll start at the back of the wing tube and work the way back from there until I find the sweet spot for me.

Also, could you reveal the tricks you did to achieve such a low weight? Light motor and ESC? Replacing the brass hinge tubes with something lighter? Light servos? I'm asking this since my plane will be somewhat overweight at first until I get a lighter motor and maybe wheels. The one I'm using now is about 650 g with the mounting HW.

The planes I saw were around 4800 g ready to fly with PT model 3-blade carbon props, NEU motor, lightweight servos, light wheels from F3A Unlimited and direct 2S Lipo RX power supply (no regulators).

GVI

Hi,
Regarding the CG, we have two evo II in our club, and we both use the 235mm, but please try it out and let me know what's your setup.
invert flight is you describe with really little push.

Enclose you can see my parts setup the part weight and the total weight of the ready to fly plane. I would say no special secrets.

FinnSpeed

Gerhard, thanks again! Especially the weight breakout is interesting. I immediately see the main differences:
1) Your motor is much lighter than mine, as expected. I'm going to replace the Dualsky motor during winter with a Hacker C54 or something comparable. This will reduce the weight by 100 or even 200 grams.
2) Your battery is also quite light. I'm starting with cheap Zippy Compact 5000 mAh packs that weigh about 1120 g, maybe a few grams under 1100 g when the wires for series connection are shortened and soldered to eliminate the heavy bullet connectors..
3) Your wings are much lighter than mine. I wonder what the difference is... The guys at Nordic championships said theirs were around 420 g each without servos and linkages.

For the rest, my equipment and parts weigh almost exactly the same as yours.

GVI

Hi, I use this Hacker Lipo. Great Quality, lightweight and cheap.

FinnSpeed

Here's some pictures of my build while waiting for the maiden flight.

One of the pictures show the mounting piece with impact nuts that I installed into the canalizer, next to the spar inside. My canalizer is detachable, secured with 2 x M4 nylon screws and 3 pcs 5 mm diameter carbon tube pins to the canopy and fuselage. This method is a bit heavier than gluing the canalizer straight to the canopy like many others have done but to me it is a great benefit to be able to quickly take it off to ease transportation. My transportation is a small Volvo V50 wagon.

The rest of the photos show the rudder servo installation and pull pull cables. The servo tray is relatively large but the honeycomb material weighs next to nothing, fortunately.

joenella

Hi Risto

Looking good.

Hope You could use some of my hints I gave You at the Nordic Championship

bem

My Feedback: (1)

Hi FinnSpeed,

Krill Spark Evo II seems to be a good choice of 2M F3A plane. All the Spark Evo II flew great in the hands of the pilots that had this plane at the Nordic Championship F3A recently.
Several pilots had two of them registered at the Model Processing. They really seems to be high quality and the color scheme on them is great also.
It will be interesting to hear Your opinion how it flies when You have it reasonably good trimmed in.

Good luck with the assembly and maiden.

regards,
Bo

FinnSpeed

Thanks Joen and Bo, it was a pleasure to talk to you face to face. I hope we meet again, perhaps at the next Nordic Championship competition in Denmark.

Joen, I got some good ideas and I'm going to do the hinge trick - I just did not have time yet. I have some other ways to optimize weight too which I may use.

I have now 12 flights on the plane - most of which were flown this weekend at Finnish F3A Nordic Cup competition. The trimming process is still going on but the first impressions are very positive. I'm trying to learn away from the specific habits the Wind S 50 has in the same time as I'm learning to handle this much more powerful plane that hardly needs full power during the Nordic sequence. The very different color scheme also needs some time to getting used to.

I started trimming with the CG at close to the back of the wing tube, around 205 mm. This is much more nose heavy than the recommendations shown here earlier but the Danish planes seemed to fly well with their CG close to that point. This setting was a bit too nose heavy for my tastes so I kept moving the battery back. Now the CG is somewhere around 225 mm which feels pretty good. I'll try to measure it more accurately later on since this is just a finger tip estimate.

I will add some more pictures of the building process and the finished plane when I have time.

FinnSpeed

Here's a few more images of my plane. Wing servo access "hatches" are supported by 0.6 mm aircraft ply which weighs almost nothing.

The motor installation is very simple: I made rings from 3 mm aircraft ply and 1 mm carbon plate and glued them into the nose with slow Araldite mixed with microballoons. Well, the 3 mm ply had to be worked on quite a lot to match the nose perfectly... Then I just drilled 4 holes to match the motor support and bolted it on using long 4 mm screws and suitable plastic riser parts. The Dualsky mounting cross is relatively heavy and I'm planning to replace it with one made out of carbon plate and aircraft ply. Finally I will replace the motor with a lighter one but this will do for the rest of this season. It pulls the plane with good authority and does not run hot.

Meanwhile I finalized the canopy locking system and will post photos later on. I don't like having to use any kind of tools removing the canopy but the large T-can puts some additional requirements to the locking system.

I have 21 flights on the plane now and it feels better all the time. I'm still trying to find the sweet spot CG but I'm getting close. I've been gradually adjusting the horizontal stab incidence to get rid of trim. Initially with the forward CG the plane needed a substantial amount of up trim but even with the CG close to the recommended range some trim was required. I suspect that the stab (or the carbon pin) was simply a bit off from the factory.

FinnSpeed

Then a couple of finds about surface movements: The rudder is very powerful and sensitive but as usual, you need all the available movement to perfect stall turns (I have been watching Lassi fly his Sensation and it turns literally on the spot - using huge rudder movement). This requires making small recesses for the rudder horns. I think I need a bit longer servo horn for the rudder as well since this one is now maxed out and the rudder has a bit more room to turn.

Elevator movement seems to be sufficient now although I may experiment with spins. I don't remember how much I movement there is now but will measure it.

The ailerons move about 40 mm up and down with full rates and the rolls are axial. I set the servo horns one spline step off to to get decent symmetry without extra long servo arms.

danielcaceres1991

Hi everyone,

I've also been flying the evo II for a while now. I've found all your comments extremely helpful as this is my first 2m F3A bird. I had my CG at about 200mm but after reading your posts I moved it back to 230mm and it is working perfectly (much better pitch control and less trim required).

I was wondering if any of you could share your different rates and expos for normal flight, snaps and spins so I can have a starting point to work from.

I'll be sharing some pics of my airplane in the next few days that may hopefully help someone.

Best Regards,
Daniel

FinnSpeed

Here's some pictures of my cabin lock system and equipment installation. I added two "hooks" made of 1 mm carbon sheet to the sides. They prevent the cabin from flexing and moving under stress. The system works quite well, the cabin is quick to install and open without tools.

The equipment installation could be regarded as a slight overkill - one could have done with just a single tray for the rudder servo and RX. I just prefer clean and neat installations and in this case the honeycomb material I used is very light. The battery tray is slightly heavier than necessary (~40 g) but it is easily removable. It is made out of two 25 mm wide strips of 6 mm balsa laminated on both sides with 0.5 mm carbon.

I have 24 flights now and the CG is now close to 230 mm (I still need to measure it more accurately). Unfortunately I don't have good rate settings yet since I started programming as the Wind S 50E setup as a base and there's lots of checks to be done after I find the best CG for me. I have three separate dual rate settings:

1) Basic state with low rates on all surfaces. These are roughly 30% of the max (rudder 50%) and relatively low expo.
2) Stall turn/spin state. Ailerons the same as basic but high rates on elevator and rudder. Basically the maximum movement achievable in both cases.
3) Snap roll state. The same as 2) but ailerons on high rates as well.

I have not tested the snap state much yet since the Nordic sequence I'm flying does not have any snaps...

bem

My Feedback: (1)

Hi FinnSpeed,
Neat installation there in the fuselage.
Have You checked the total flying weight yet?

/Bo

FinnSpeed

Bo, I did not check the exact weight yet. Today I mounted the Nurila carbon 20 x 13 prop for the first time and tested it. It affects both the CG and total weight since it is much lighter than the APC E. I'm sure the plane is still somewhat overweight but I will check the exact weight soon. The first goal is to achieve 3900 g without battery.

John F3A Junkie

Hello Guys,
Is it just me or the fin+rudder of the Spark looks quite small compared to the side area of the fuselage? Especially, compared to latest F3A planes i.e. the allure, proteus, essence etc..

regards,
John

FinnSpeed

I have now installed and started testing the Hacker C54-2Y L Acro Competition motor I mentioned in the other thread. The motor is 180 g lighter than the original DualSky and the new lightened (88 g) Hacker Master Spin Pro 99 drops the weight a further 36 g. As a result, the plane now weighs almost exactly 5.000 kg without wheel pants (with 1120 g battery). I will weigh it soon with a Mettler Toledo precision weighing scale to be sure.

I was a bit worried about the CG point since obviously removing more than 200 g of weight from the nose could cause problems. Luckily I had made the battery tray fairly long so I was glad to find out there's still an inch available if I want to move the CG forward.

The plane handles differently with this motor. Even I can feel the weight loss and smaller gyroscopic effect compared to the relatively massive outrunner. The power is also there - using Nurila 20 x 13 carbon prop the old setup took 86 A @ 6650 rpm. This one produces about the same rpm with only 73 A. I'm going to make more measurements and confirm with external tachometer (I read the rpm from the Spin ESC). The sound is way different and not bad at all. I rather like the gearbox whine since it is easier to hear in the air which helps throttle management a lot.

By the way, I had a funny episode with the JetiBox I borrowed from Janne Lappi. He had not used it yet and this was the first time I ever used one too. It wouldn't connect to the ESC no matter what I tried. Then I asked some help from Lassi who sold the ESC to me and he sent some pictures of how he connects the JetiBox... Turns out, the little sticker showing the connector positions was placed upside down by the factory! I corrected this and tried the proper connection which worked immediately, of course.

FinnSpeed

I checked the accurate weight today and it is 4995 g if the battery weighs 1120 g. That is the weight of my heaviest set of Zippy Compact 5000 mAh batteris - I think.

I also mounted the spinner and checked temperatures after flying when the ambient temp was 25 - 26 deg C. The air duct works well since the JetiBox told me that the ESC max was 40 deg C and the motor was about the same. It felt warm to the touch but not really hot.

FinnSpeed

A question or two to all Spark Evo 2 owners:

Have you measured your wing and stab incidences? Looking at the control surface positions (ailerons) when trimmed to fly straight, at least the wings must be pretty close to symmetric. The problem I have is I don't know if my stab halves are exactly in line with each other. I'll find out sooner or later since Janne was talking about buying an incidence gauge... I have had to use almost the whole adjustment range of the stabs to get rid of elevator up trim. I adjusted them (or tried to) exactly half a turn every time so if factory preset was symmetric then my plane should still be OK.

How much have you adjusted your stab incidences?

jjldk

Hi All
Nearly finish my Evo. 2.
What are your settings for the wing / stab incidences?

Thanks in advance
/JJ

FinnSpeed

I still have not done the incidence measurement. The wings are not adjustable so I wouldn't worry about them too much if you trust the factory.

For some reason (as told earlier in this thread) the stab incidence in my plane was negative CORRECTION: positive! from factory which caused a lot of up trimming during the maiden flight. I would try to get that closer to zero if it is too much on either side.

What is your setup/weight? Mine is competition legal but does not allow very heavy batteries and I have been thinking about building lighter wings.