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Old Today, 01:46 PM
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What about some flaps during take-off. Doesn't it help with AoA, insufficient lift and nose gear problems?
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Old Today, 02:05 PM
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You know, the more I think about this situation the less sense it makes. This is my 6th Freewing TV plane and the only one that presented any problems on maiden or for hundreds of flights, pilot error not withstanding. F-16, Su-34, F-35, F-18 and Eurofighter. Not one issue with any of them. Set them up, plug in the battery and go fly 100's of times.

So why do I need to fiddle around with all kinds of adjustments to merely get this particular PNP in the air? That borders on the absurd. What's wrong with this picture? This is a Freewing and this is PNP.

Rant over.
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Old Today, 02:49 PM
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Many did fly it as is. When some had the little quarks then they made these trim changes. For me grass motivated the need for the little optimizing.

If it wasn't for the supposed ESC failure, you may have just flown it as is cause they will get off the ground if you have the runway length and go full deflection even off grass.

It's if you want to tweak a very scale look to your ROG or are flying off rough surfaces. Otherwise you could force the jump off the ground like some of the ones you mentioned do.....
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Old Today, 03:39 PM
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Originally Posted by Maxthrottle View Post
Many did fly it as is. When some had the little quarks then they made these trim changes. For me grass motivated the need for the little optimizing.

If it wasn't for the supposed ESC failure, you may have just flown it as is cause they will get off the ground if you have the runway length and go full deflection even off grass.

It's if you want to tweak a very scale look to your ROG or are flying off rough surfaces. Otherwise you could force the jump off the ground like some of the ones you mentioned do.....
I guess that's the point. It should have gone in the air one way or the other, stayed in the air, and then the tweaks as required, as almost any plane might require. 300' and it wouldn't be forced off the ground.
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Old Today, 04:18 PM
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Quote:
Originally Posted by 19000rpm View Post
So why do I need to fiddle around with all kinds of adjustments to merely get this particular PNP in the air? That borders on the absurd. What's wrong with this picture? This is a Freewing and this is PNP.
While I am sorry that I do have a solution for you, I completely agree with you.

Have you checked to see if the impellers are mounted in the correct shroud? See these two posts.

http://www.rcgroups.com/forums/showp...ostcount=20081
http://www.rcgroups.com/forums/showp...ostcount=20086
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Old Today, 05:26 PM
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Originally Posted by T3chDad View Post
While I am sorry that I do have a solution for you, I completely agree with you.

Have you checked to see if the impellers are mounted in the correct shroud? See these two posts.

http://www.rcgroups.com/forums/showp...ostcount=20081
http://www.rcgroups.com/forums/showp...ostcount=20086
Something I NEVER considered.

When I balanced the 6 blade fans I took them out individually, balanced the fans, and then reinstalled the unit before I took the other one out. Since I assumed the housings are identical... Could that possibly be the issue???
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Old Today, 05:44 PM
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When everyone learns a bit more about complex aerodynamics, such as this Su-35 has - well above almost all other model jets - they will work out why it struggles to take off.
A VERY notable amount of lift is lost due to the underside cheaters - enough that adds into the total mix and can MATTER on this jet. Anywhere from if just making take-off harder (yet can't be discerned as it flies and all seems fine), to not taking off at all. And any amount in between.... taking longer than it should and then leaping.
Leaping ALSO has other factors in its cause, but there are a bunch that all tie in together.

I have a lot of jets... not one other "can't take off", nor struggles much on grass (my low cut, good sports field grass) and my Su-35's have far more power than stock (2600W to 3000W). And are also equal, or more, high power to my other jets (some are equal and a few have more). And they weigh (AUW) anywhere from the same, to a bit more, or a bit less, than the others. ALL my jets are in the 4.0Kg region - with a couple as low as 3.5Kg (just 2).
AND the Su-35's have THRUST VECTORING and that can't even help enough!!!

I have seen it "wallow" when coming out of low speed 'not flying' situations - where WOT of that 2600W+ struggles to fly it out. BUT, it can float in at 'double walking pace', 10 to 15deg nose high, at dead stick to land!! That shows it has a TON of lift that can carry my 4.2Kg totally fine - WHEN it gets it ALL !! And also shows how it LOSES lift under WOT.

It doesn't take rocket science to see what would happen with 2500W plus of suction under a plane.... under its "Wing" - lifting body (tunnel). Put it in a wind tunnel and you are going to see airflow ROCKET into those cheaters, predominantly from the tunnel and FORWARDS (not from vertical below). That suction vector will alter with airspeed.... the faster it goes, the more horizontal from forwards it will come, and eating away at the underbody lift then. And to go faster it needs more power... so it has more suction... and that resultant detriment FOLLOWS and can sometimes even outrun the speed/lift balance that it gains.
The take-off run is the worst case of all those factors.... running FAST, and NEEDS the lift it is losing to that then horizontal suction vector.
eg If you can get enough AoA, the lift gain from that will outrun the loss.... but at zero AoA stance (or even my +2deg) that is not enough to overcome it.
Mind you it seems that on a HARD runway the lower friction level allows enough speed to raise lift above the detriment - even my 4.2Kg will fly off a road fine. This is because the same "2600W", thus same suction and lift loss, is occurring but you can go faster due to the lower friction. But on grass it can't afford the speed loss AND the lift loss due to suction. Demonstrated by how it DOES fly off strongly under ZERO throttle if you remove the Power, thus thrust and suction - and not 'just fly', it ROCKETS skywards on pure momentum it had and then gets to unleash in a normal aerodynamics manner then!

----
For your case..... you can space out the nose leg 13mm approx and the doors will still close. That should/would get it off the ground for sure I would expect (I did that for my Su-35-01).
The next part - where yours had some issue AFTER lift-off.... well that is something "gone wrong" because once in the air they fly totally fine (even with their Throttle linked waste of underbody lift).
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Old Today, 05:45 PM
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Quote:
Originally Posted by 19000rpm View Post
You know, the more I think about this situation the less sense it makes. This is my 6th Freewing TV plane and the only one that presented any problems on maiden or for hundreds of flights, pilot error not withstanding. F-16, Su-34, F-35, F-18 and Eurofighter. Not one issue with any of them. Set them up, plug in the battery and go fly 100's of times.

So why do I need to fiddle around with all kinds of adjustments to merely get this particular PNP in the air? That borders on the absurd. What's wrong with this picture? This is a Freewing and this is PNP.

Rant over.
Flaps are not needed, i never had issue with rotating off the ground. Also no ned for flaps to land. if you know the plane and the landing profile its a dream to land on a smooth runway. i have many videos demonstrating this.
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Old Today, 05:53 PM
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When I have tried Flaperons they do NOTHING of use for take-off.
Definitely no help to rotate, and likely to cause NOSE DOWN rather than benefit anyway! (all you will see is no change', whether they are driving the nose down more to any visible degree or not)
The 'redirected downwards air vector' is AFT of the CofG - even the more rearwards than the landing gear pivot point - thus it exceeds and negates the potential lift gain of them.

If a plane if FLYING, and thus 'free' from its ground 'chain' of landing gear, THEN they give lift totally fine as intended/desired. Because you will put the plane into a higher AoA yourself - and it is possible then.

If you could add Flaperons during take-off only AFTER it rotated, then they would give lift assistance... but by then it is not needed and irrelevant anyway. The greater AoA is more than enough to fly off with ease (even at 4.2kg).
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Old Today, 06:11 PM
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Also...
You can't compare this model Su-35 to the full scale... by a LONG way. Nor to any other full scale aircraft.
This is because it has a BUNCH of factors that displace it notably from the full scale.

Things such as, they run a far more rearwards CofG than we can.
They do not have huge sucking cheaters in their underside tunnel.
They have TV, and all other surfaces, that are ACCURATELY controlled by a computer system.
They have far more than enough ability to rotate without question for any take-off they ever do.

I have not watched closer detail of the full scale taking off. They might use some Flaperon - or might not. But in their case the 'early on detriment' it irrelevant to them anyway - because they have that TON of Rotation ability anyway.
This means they can (could) deploy them from standstill and the 'zero AoA' down the runway, where they are more detriment than good, and it is negligible/irrelevant. But the INSTANT they Rotate they become useful - as that is when you need the LIFT to be working.... so it can fly upwards and away.
If you had a flight computer, it would, could, be programmed to do ANYTHING with zero effort at any time - but imagine if a PILOT had to do it all manually. That means there is no way they would ever have them up..... and quickly deploy them as the plane rotates! That is far too difficult.... but a flight computer COULD do that with zero effort.
That does not mean the PROGRAMMERS do set it up to operate at Rotation.... they can program ANY sequence they see 'best' for whatever reasons they arrived at that decision.
Just like an F-16 uses UPWARDS LEF's during the take off run, but they instantly flick to DOWN as it lifts its nose - they are either running off AoA sensors, or even just the a sensor off the nose gear loading.

So it would be interesting to see what the Su-35 does use..... and it could even be VARIABLE. A chosen function, only used for short take-offs.... or maybe varies in flight program versions.... or even totally dynamic (changing) as all the OTHER flight factors of an given take-off vary from one flight to another (cross wind.... higher payload.... takes a slower run out on a longer runway... etc etc)
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