Freewing Su-35 Twin 70mm 12 blade

[Airguardian]

More kittens dying in agony for your collective delight!

[Airguardian]

Two particularly screechy kittens it seems.

[kallend]

I hope the following video serves an educational purpose:

. ;)

Was someone strangling a cat in the background while you were flying?

[Airguardian]

I hope the following video serves an educational purpose:

These were some flights I made earlier this year, and due to bad runway conditions and not having flown the Su-35 for a while I messed up and got myself straight into a textbook case of PIO (Pilot induced oscillations). In this case, triggered by requiring full throws to take-off at too low speed (forced by bad runway conditions), followed by delay in neutralizing the input, then overcorrecting, and then overcorrecting the overcorrection, and so on, and so forth.

Thankfully I was able to eventually pull out of it and keep the plane in one piece but at any point I could just as likely have smashed it down to pieces.

The point I want to make here is that my plane is (was) NOT tail-heavy. It is balanced with CG pretty aft, which makes it extra agile-twitchy, but it still has positive longitudinal static stability, that is, the plane is stable. If I take my hands off the transmitter when the jet is cruising, it is going to keep cruising pretty much level.

Many would have an episode like this, assume their CG is too far aft and resort to move it forward in an attempt at curing the problem.
My footage clearly demonstrates that a well balanced airplane is still perfectly capable of entering a PIO condition.
Furthermore, there are documented cases where building too much 'stability' into an airplane (for example a manned cessna or an airliner) is even more likely to have pilots inadvertently get into these dangerous scenarios that are usually hard to get out, and more often than not, end with a crash.

Other than the huge scare, you can see that the rest of the flight proceeded uneventfully, and I was pulling the usual aerobatic shenanigans. I didn't even have to retrim afterwards.

So that's that. Have it as a word of caution.
My take on it is: try not to blame everything on tail-heaviness right out of the box, without more thoroughly investigating the issue and making tests to clearly identify if the plane is actually tail heavy or not by conducting the appropriate flight tests that conclude that. ;)

[Airguardian]

In short... there isn't!


Congrats on re-maiden!

[TangoVector]

I re-maidened and flew six flights with my upgraded Su35 today and it performed as well as I had hoped!

New modifications except most of the things Airguardian has in his video:
Elevator servos from Turnigy, much better resolution.
New EDFs FMS PRO 12b with 80A ESC
Separate BEC 10A.
New Main landing gear from Freewing F15.
New nose gear from Freewing Avanti.

Flew from a grass field that really could need some mowing but it leaped to the air very quickly with the VT on. The new EDFs gives it very good performance and they are actually quiet. So all in all I'm very happy, but a little disappointed because I don't know how there will be a more fun to fly aircraft to get?

[Airguardian]

Some more powerful fullscale inspiration :)

[Airguardian]

That may prove tricky, as the front end is the one that typically suffers most from a crash.

[JLambCWU]

JLambCWU how did you make your 2 seat cockpit?
I'm planning on building an SU-30SM using the SU-35 as the base, so a 2 seat cockpit is a must

Cockpit from someone’s wrecked FMS/Eflite SU-30

[Airguardian]

Best inspiration for the #FlankerGang!

[Airguardian]

And have some more:

[Airguardian]

Have some fun! :)

[mshagg]

Interesting that the peak current I've measured in the SU with my FMS PRO units and 80A ESCs with a 6000mAH HRB pack is 136A (= 2 x 68)

I've measured higher currents in singles with the same ESC and EDF. Maybe the current is limited by the pack IR in the twin.

That's pretty consistent with the RCG testing of that pack which they rate as a true 30C.

I maxed out a 150a current sensor running the FMS pros on high timing. Although measured 4.4kg thrust doing so. Never actually flew it in that configuration.

Low timng was 138A. Testing was on a pack that performs slightly better than an HRB.

Twin 70mm is no joke when it comes to power consumption!

[kallend]

Crazy that a motor that does 68A continuous would be paired with a 60A ESC. Luckily I have 2 spare 80A's from an ill fated F-14

Interesting that the peak current I've measured in the SU with my FMS PRO units and 80A ESCs with a 6000mAH HRB pack is 136A (= 2 x 68)

I've measured higher currents in singles with the same ESC and EDF. Maybe the current is limited by the pack IR in the twin.

[Airguardian]

Well, someone has definitely messed up along the way... They should have upgraded the ESCs too IMO.

[haljennings]

Before I ordered the new version SU35 I called Motion and spoke with Tim asking the direct question "did this version come with 60 or 100amp esc's" he said 100amp.

[paulrkytek]

[QUOTE=KevinMar;n317192]Crazy that a motor that does 68A continuous would be paired with a 60A ESC. Luckily I have 2 spare 80A's from an ill fated F-14[/QUOTE

Good swap in any event, better safe than sorry.

[KevinMar]

Crazy that a motor that does 68A continuous would be paired with a 60A ESC. Luckily I have 2 spare 80A's from an ill fated F-14

[paulrkytek]

Paul, the Su-35s that came in the latest container to the US warehouse now ship with 2100kv inrunner motors, so they are indeed upgraded in that sense.

I still think 60A ESCs is borderline for these setups. Particularly if you want to get all the juice out of it at high timing, they may be more prone to overheating than higher amp-rated ESCs.

Jandro I read EU warehouse 60amp at the moment with outrunner. I agree 60amp borderline, my post just answered haljennings question about why motion r.c did not upgrade esc even though it would have been better at 80amp. I was putting myself in Motion r.c. shoes current us version as of now states Version Info: This is the High Performance version of the Freewing SU-35 Desert Camo. This version includes two powerful 2952-2100Kv brushless inrunner motors with 12-blade fans, and two 60A ESCs for exceptional speed and performance. I dont know what power/thrust this fan produces, if indeed the website is correct ? Its a bit confusing and needs sorting out.

found this to add to the confusion ;- if correct needs 80amp esc so motion website probably still not correct ?

Motor Type	Inrunner
kV Rating (RPM/Volt)	2085kV
Maximum Watts	1580W
Continuous Current	68A
Maximum Burst Current	75A, 10 seconds
Recommended Battery (Input Voltage)	6S (22.2V)
Recommended ESC	80A
Recommended Propeller / EDF	70mm 12B metal fan
Slots, Poles	12, 4
Shaft Diameter (A)	4mm
Shaft Length (B)	16mm
Motor Length (C)	63mm
Motor Diameter (D)	29mm
Overall Length (E)	79mm
Weight	183.4g / 6.46oz
Connector Type	4mm Bullet

[mshagg]

The MRC ad clearly states 60A ESC.

Power System	2x Brushless 2952-2100Kv
Speed Control	2x 60A Hobbywing, EC5 connector
Propeller / EDF	2x 70mm EDF 12-Blade

https://www.motionrc.com/collections...toring-jet-pnp

When I upgraded to the FMS PRO units I put in 80A Hobbywings.

They have corrected a typo which was on the page until recently. The blurb read "This version includes two powerful 2952-2100Kv brushless inrunner motors with 12-blade fans, and two 100A ESCs for exceptional speed and performance".

I commented on the other forum that this seemed unusual given the AL37 and Me262, which have the same powerplants, both still shipped with 60A. Jandro was excited at the prospect of some extra headroom for the PNP, but I see this has now turned to disappointment lol.

I can see his point - both the airliner and the schwalbe have better airflow arrangements for the ESCs than the sukhoi does, and are (one would hope) less likely to be drawing lots of power in a post-stall condition.