Espritmodel.com Telemetry Radio
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Old Nov 19, 2011, 09:15 AM
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Maxthrottle's Avatar
High Orbit.....
Joined Jun 2009
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Well Benjo,
When I first watched the vid I thought the pop up was generally less pronounced on this one than many models or that the pilot popped it up because he was running out of runway.

Pop up has usually, in my Freewing observations, been due to main gear placement and AoA that the gear profiles the wing for roll out. E.g. The Euro had no cheat had the gear in the right place but stopped the pop up effect once we increased the nose strut length a little more than half an inch.

Too, if you examine the FS SU 27 designs, several have cheat louvers... Most like this one with them on the bottom of the intake, others added in board and or out like on the FS SU-34. So this is actually a part of the design where they opted not to add the cheats on top like the F22 does or more close in design the F-14 or Mig29.

With the Su-34 I found the pitch up more to do with wrong thrust line angle which many found as they changed the TV angle to remove this.

All the above doesn't null your the accuracy of your comment but while true, I'm not certain of it being dominent enough making it worth changing anything to yield better result. If SU designed them this way, what might you be doing to the top surface why they chose not to, is a question I'd ask myself. When you get yours try it and let us all compare.

I was going to suggest trying the recent tensioned closable louvers F22 experiment that had the cheat louvers both top and bottom, with on board readings recorded. I'll ask him for his next test to compare top cheats vs bottom cheats.
But in the discussion we spoke of being able to shut the louvers by servo, in that case for top speed passes. However, for this model you could apply the same for roll out....

This model though is wing loaded low enough and will float much like the SU-34 did. Lift loss could easily be nullified by flapperons and a constant powered controlled approach....

Just some ways around your concerns if they do present.

Oh and the T-50 has a LERX system. The SU-27 Fam's strakes/blended body don't move.
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Old Nov 19, 2011, 02:27 PM
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SU-4ever's Avatar
Spain
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Quote:
Originally Posted by benjo View Post
CHeater holes underneath reduce your lift. Su-34 looses altitude when you nail the throttle because you suck some lift away. Lift works by speeding up air over the wing cuasing a lower pressure on top (there are other ways but lets not talk about them). now speed up the air underneath the plane as well by sucking this air into two screaming fans, sucking away the high pressure that would be giving you youre lift. Not always pleasing to the eye but cheater holes work better on the top. I put cheater holes underneath one of my other edf's and notice it had alot more power and alot more speed but it didnt fly as well and was dragging its ass around like it was underpowered. I discovered better flying characteristics and WAY shorter take offs putting cheater holes on top (once again, lowering the pressure on top the the plane even more than usual is always a bonus on take offs especially if you have to take off from grass). It also eleminated the tendancy to lose altitude when you increase power to soften the landing, on a lot of edfs doing this makes them slam harder into the ground, I sure im not the only one to notice this. I also sucked in less Debriss into the fans. These are just my findings, put cheater holes wherever you want.

You wont get rid of these tendancies totally on a sukhoi because the intakes are below a lifting surface, the LERXes and blended fuselage so threre will always be some loss in lift depending on the attitude of the aircraft and what you are doing. So when you give the Su-35 throttle, there are three areas where lift is lost, left intake, right intake, and by the looks of the photos, center fuselage.

Oh, one more thing, cheater holes underneath can suck the aircraft to the ground on take off, increasing take off distance. On the plane I mentioned earlier, It would be doing mach 2 on the ground and not take off. I would give up, cut throttle for another try and the thing would 'pop' up into the air. This went away once i moved cheater holes to the top.

On the first flying vid of this new su-35 you can see it pops up instead of takin off nice and smooth as foreward speed and elevator input overcomes the suction and it suddenly pitches up.
That's all aerodinamically right but you are missing one big point.

The cheater holes only make sense at slow speeds, to let the fan suck a higher amount of air and not get drowned. At high speed you have more than enough 'air sucking' through the intake holes so no cheaters needed. The very point of cheaters is HIGH ALPHA and alike, and they are using the bottom of the wing's air overpressure to feed the fan. Opening the holes on top is great for lift as you said, but your fans will be working with not enough air thus loosing power, (And lift in a high alpha is also contributing more to drag so the plane will stop first with cheaters on top) something you don't really want to happen at great angles of attack. So, I agree with all that you said, and I know performance with the cheater holes underneath will be worse but I'm still going for them in order to assure I have Full-throttle response in 3D manuevers.

There's also one more thing, if you are doing a cobra (Assuming we manage to do that with this new model) the boundary layer will be detached from the wing top and ther'll be very little presure there so it's difficult for the fan to get any air at all. In fact the air sucked through the eintake might actually leave the ducting through them, and you'd stall when the fans stop giving enough thrust to keep the plane up.

There's just onething that I don't know. This is: maybe if the fan is really sucking air from the top of the wing, it is giving these particles great quantity of movement and that would delay the boundary layer detcahment thus producing more lift and actually being a really improvement to lift, then you'd be right. We should check that out!

I'll be tuned to hear from your results!


And to end this, I have one crazy thought, let me know what you think about it:

We're not managing to do "cobra" maneuvers because our wing loading is low and the airplanes stop soon. Then, might the lose of lift produced by the cheater holes be actually "sucking the plane forward" and virtually making it appear as it had more wing loading?

That, I think is an interesting question and something to think about.

(Have I already told you that I'm a freak of Cobra's aerodynamics?)

Cheers,
Jandro.
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Old Nov 19, 2011, 02:34 PM
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Has anybody heard if this will be eventually carried by a US dealer?
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Old Nov 19, 2011, 07:27 PM
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benjo's Avatar
Joined Aug 2009
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Well, think what you guys want to, I have modified two planes with the same results. I have a freewing Su-34 that has been modified into an Su-33 much like this new Su-35 but with the canards. Ill be getting rid of the cheater holes from underneath after my past results. If Anyone has pulled these things apart before you will know moving cheater holes to the top is no easy job. But In my opinion its worth it. I am not telling you guys to do anything, and like i said before, these are my findings from my own experiments. but i know ill enjoy better flying from my Su-35!

Su-4Ever, You are right in saying that at higher speeds, the cheater holes will have less effect. While true, If your plane has a lot of drag and small wings, like my F-14, I found i was loosing lift in the body which produces much of the plane's lift especially in sweep back, I was flying very quick but with nose slightly up. This would also be due to the fact that the intakes were not very big to make it look scale. It was sucking the air it needed, and it needed the cheater holes. It felt like I was flying around at high speed while still stalling. Backing off the throttle let the thing glide.

Another incident was flying my starmax 90mm F-18, on a higher than usual alpha landing approach i gave it throttle and this cause it to slam into the deck. The extra lift of the LERXes was suddenly taken away when I sucked all that high pressure into the intakes. Nothing can be done about that, its just the design of the F-18 and how much static thrust a big electric 90mm fan has. Powerful stuff.

At slower speeds cheater holes are more important. And At the slower speeds, its more important to have more lift, and therefore not having cheater holes under your plane adds lift bonuses. I would think a plane could hold a better cobra if the cheater holes were on top as this would be making a lower pressure above the plane helping it hold a high alpha easier. I have the small Banana Hobby MiG-29 with TV and It has been modified for all moving stabs. While this help it hold a high alpha it is fighting the cheater holes, I was doing a High alpha and got too slow, I nailed the throttle and what does it do??? Fall stright out of the sky and lucky for me, only did a hard landing but it fell a long way. I knew I should have moved these cheater holes BUT I DIDNT. I also knew to go easy on the throttle because of this but its hard to fight instinct. Eh? When I do change this, Ill inform you of the results. This jet is also guilty of the full speed no take of phenominon. And thats even after adding drooped leading edge. You are also correct in that the having a taller nose leg helps take off thats obvious. This did not help my tomcat when the cheater holes were underside. Like I said earlier, cut throttle and the thing would leap into the air. Freaky. (Russian carrier take of ramp anyone? Man, the more i think about those, the more i want to build one to try!) We're not going to stall the fans or have no air to suckinto them having on top, the air is there, the thing isnt flying fast enough, isnt big enough, and electric fans are pretty poweful, theyll get the air they need. Come to think of it, one the second experiment of putting cheather holes on top I had my plane a bit too tail heavy and it took off before it was even fast enough to control with just the all moving stabs, I had my cheater holes too close to my stabilators as well maybe? now that was an exciting moment. haha. Maybe i broke the record for the shortest take off with an F-14 EDF

This leads to another experiment. Covering the cheater holes with a very fine mesh might help the air bypass the cheater holes even more at high speed when they are not needed. This may help the high speed flight of my jets that still have underside cheater holes, we'll see.
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Last edited by benjo; Nov 19, 2011 at 08:14 PM.
Old Nov 19, 2011, 10:52 PM
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Quote:
Originally Posted by Flip Flop View Post
Has anybody heard if this will be eventually carried by a US dealer?
I haven't heard but it's almost a given that Hobby Lobby will carry it.
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Old Nov 20, 2011, 08:06 AM
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hope that includes the VENOM as well! Cheers
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Old Nov 20, 2011, 03:32 PM
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Joined Dec 2008
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Delays

Hi there,

just keep in mind that the time difference between a distributor having a demonstrator and general availability can be very big. R2F originally announced the LX MiG-29 for May 2010 availability. I got mine in late October. So don't hold your breath yet for the Su-35 and don't sell all the other planes you have !

Cheers,
Henrik
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Old Nov 20, 2011, 05:10 PM
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Quote:
Originally Posted by hklagges View Post
Hi there,

just keep in mind that the time difference between a distributor having a demonstrator and general availability can be very big. R2F originally announced the LX MiG-29 for May 2010 availability. I got mine in late October. So don't hold your breath yet for the Su-35 and don't sell all the other planes you have !

Cheers,
Henrik
Whole LX Story is something completely different.

LX had issues for some reason to ship them out in time..maybe they added a few more christmas lights, made the retracts worse..putting a exploding sequencer on the escs..made the edf units out of invisible very thin plastic which led them to explode..used pcb toy boards on it which never worked...or let the homer build the servos.

The list goes on and on..Funny enough that with all the delays which LX had..they actually never improved on their jets when it comes to electronic QC, it was just as bad as it was once they first announced it..


And what is the Moral of the Story? Time to go to bed.
NS.
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Old Nov 21, 2011, 06:21 AM
You are a "go" for reentry
Maxthrottle's Avatar
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Joined Jun 2009
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NS it was asked but on the Ready2Fly PnP version, the site states the impellers counter rotate. Is this true?

You also mentioned that the black and white paint scheme was sent back to add more blue to the black??? All the pics of the full scale appear a tone of black not blue. Black is cheaper also. Are they really thinking of changing this?
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Old Nov 21, 2011, 07:22 AM
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Luzern/Switzerland
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Quote:
Originally Posted by Maxthrottle View Post
NS it was asked but on the Ready2Fly PnP version, the site states the impellers counter rotate. Is this true?

You also mentioned that the black and white paint scheme was sent back to add more blue to the black??? All the pics of the full scale appear a tone of black not blue. Black is cheaper also. Are they really thinking of changing this?
Hi Max

Yes the Fans are counter rotating like stated.

The Paint Scheme was not send back but rather Freewing decided to actually make it look like this here:



They are already changing the Paint Scheme for the upcoming December/January Release.

Plus there a minor changes on the SU-35 anyway like for the retracts.

@All

The Retracts would make a grass takeoff possible, but you may need to take the plastic piece on the front wheel away so it won't act as a brake on grass.

The Big Main Gear wheels should make a takeoff from grass a breeze.

NS.
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Old Nov 21, 2011, 07:52 AM
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Btw, the thing behind the nosewheel is a mudguard.
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Old Nov 21, 2011, 07:56 AM
Fly & Have Fun..Enjoy the Ride
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I cancelled my order status and have decided to wait to see the actual production release.
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Old Nov 21, 2011, 08:00 AM
Fly & Have Fun..Enjoy the Ride
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Neversommer ...what is your relation to "ready2fly " ? Or the company handling the plane/product?
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Old Nov 21, 2011, 08:05 AM
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Originally Posted by brandonmoon View Post
Neversommer ...what is your relation to "ready2fly " ? Or the company handling the plane/product?
It depends,why?

NS.
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Old Nov 21, 2011, 08:06 AM
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Quote:
Originally Posted by fredmdbud View Post
Btw, the thing behind the nosewheel is a mudguard.
Cheers for that Fred

Could not think of the right word as of how to explain.

NS.
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