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Old Apr 16, 2012, 12:17 AM
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Thanks Kevin.. Im not real worried about it, i'm using the original 2100KV motors which used 50amp ESC's and upgraded them to 80AMP (non bec) Castle ESC 's I have a 10amp BEC to add in.. These ESC's have 2 large caps on each, I think he said 470's? I am going to use a 5000mah 30-40c 6s single pack.. thats up from the recommeded 4000mah 25c..

I am hoping that the upgraded ESC, basic wing and tail metal gear servos and the RC Lander gear will produce a nice airplane that will last a while.

thanks for the help..
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Old Apr 16, 2012, 12:47 AM
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4 more flights today. Awesome as always. Getting better at high alpha, and a did the longest clean axial roll I've managed to date, about 3 seconds. I managed one nicely formed cobra complete with recovery, but I couldn't duplicate it. I did it downwind which was unexpected.

Thought I'd post a note about a small mod I did. I was having trouble with the stock wheel coming apart due the the weak rim material, and also the axle buckling under the pressure and rubbing against the strut. You can observe that in some of my older photos. I went to my LHS looking for replacement wheel and found that the Parkzone P-47 LG set is a pretty good replacement. Same exact diameter and axle size, just a little bit thicker, a less bouncy material, and yet they look almost exactly the same as the stock ones. The kit comes with very sturdy struts. Here: http://www.horizonhobby.com/products...s-p-47-PKZ5303

I took out the stock axle and wheel, and cut the P-47's struts to a short L shape, and made a small flattened section for the grub screw to grab on to. It slides right into the hole in the stock SU-35's strut, and the wheel is secured with a simple collar. This material is *much* stronger than the stock axle, as are the P-47 wheels. Tried them today and they worked like a charm. My wheels are now perfectly straight and there's no buckling.
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Old Apr 16, 2012, 01:02 AM
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Originally Posted by Maxthrottle View Post
Was going to do the nose gear single door for scale but if I ever belly landed it would certainly rip that door off.

Its not clear what rotation method he's using. It actually looks to be the same PZ rotationals that you see on the FMS setups; not th ball link rotational method. He bent the main rod like a Z bend to create the offset so the wheel clears the duct. Thats a great simple solution but that setup will encounter even greater toeing out force. Not sure if the grubs would hold up.
Like he said, work in progress.
I was going to say that those look alot like the retracts from my airfield 1400mm p-40. yes they look awesome and to scale (they'd even look more scale if they used the main struts from the eurofighter like was suggested earlier)...now that i think about it the wheels on the p40 are about the same size too...and it's not flying right now...hrm *thinking evil canibalism plans*. thanks V8 and maxthrottle for clearing up the whole cs10 thing...though i would like to point out this video
HK Durafly Vampire - CS 10 Blade 70mm EDF - Turnigy L2855-2300kv motor (1 min 13 sec)

i know you can't believe everything you see on youtube but those inlets and outlets for the fan can't be bigger than the ones for the suhkoi, also he is using a 2300kv motor and drawing under 40A (tho no mention if this is full throttle or not). i guess i'm going to have to take the plunge sometime if i'm ever going to find out, but as for right now i think i'll take your advice and not mess with the fan (that is until i'm a filthy rich supervillain like vladamir putin and can afford such things).
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Old Apr 16, 2012, 01:59 AM
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CS10 4S... 40A can be typical. (out to 50A). If not able to 'pump' the air the output power will be lower, and thus Amps lower too.
The CS10 needs close to 60A on 5S to produce 1.4Kg thrust.

The main issue of the Su is to be able to use 6S... which will need a low KV motor (that 2000kv or lower), plus how to get the same 1.4Kg or 1.5kg thrust out of it, for a current draw that can be coped with.

A guess.... to get just 40A use on 6S for the CS10 in the Su.... just use a very low (useless) KV motor.... ie 1600kv. LOL
And you will have bout 1Kg or so thrust if you are lucky. Not something you would do, just some numbers on what you would achieve (or not achieve of use).
Those numbers on the Vampire (40A) would probably only give around 1kg thrust or so anyway.
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Old Apr 16, 2012, 02:41 AM
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Has anyone tired to use brass inserts in the stock wheels to act like a bearing? Since mine has not flown yet, I'm just thinking ahead of some options..
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Old Apr 16, 2012, 03:51 AM
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Technically a good idea (if the wheel holes wearing is an issue of note - seems it is? Though that surprises me.). But you need to ensure the brass bush is actually 'locked' to the wheel, not just a sleeve that could then spin in the wheel hole anyway. Though an effective larger diameter 'shaft' would wear slower too then.
Rough up the bushes' outer and use CA??
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Old Apr 16, 2012, 03:59 AM
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Seeing I put XT150's on the Su's power leads and I don't have the power meter changed up to those yet, I could not test the current draw tonight.
The thrust... hmmm.... 2.1Kg WOT, seemingly lack lustre. But that was via a pull system, which I hate any form of thrust testing via pull system... but it was fast and easy to do.....

Now I have to head out back again, with a vertical scale system. That is a more accurate way to get the real thrust. But how much over 2.1Kg will that go??? I wouldn't expect more than a few hundred grams more (due to pull scale system loss/error).

And also, out of the plane the fans were pretty smooth once set up and 'balanced' (via rotor rotation only). So they seemed fine. But in the plane, as they come through 2/3 throtte area at least one causes severe fuselage vibration. Which is what they were doing in the first place as it came.
I am not sure why.... maybe something harmonic occurring in the fuselage/ducting? Gone by 3/4 throttle or so, but any vibration etc is annoying.
Maybe the way they are being held in has a slight misalignment or pressure on the housing.... I don't know (yet).
Someone's posted video a little while back sounded to have the same issue really. (When I commented on how it sounded 'terrible').
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Old Apr 16, 2012, 06:45 AM
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Quote:
Originally Posted by Edwards Rc View Post
Thanks Kevin.. Im not real worried about it, i'm using the original 2100KV motors which used 50amp ESC's and upgraded them to 80AMP (non bec) Castle ESC 's I have a 10amp BEC to add in.. These ESC's have 2 large caps on each, I think he said 470's? I am going to use a 5000mah 30-40c 6s single pack.. thats up from the recommeded 4000mah 25c..

I am hoping that the upgraded ESC, basic wing and tail metal gear servos and the RC Lander gear will produce a nice airplane that will last a while.

thanks for the help..


Are new ESC s needed? Are people having problems with the. 55a stock ESCs?
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Old Apr 16, 2012, 08:21 AM
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Just 2.2 Kg for vertical testing..... hmmm, something amiss somewhere it would seem. 2.1.... 2.2.... that is within tolerance of variation for tests, or even for horizontal testing to have loss due to drag.

The plane weighs 2.9Kg.... so 2.2Kg - even if it gets a bit better in the air - is not overly good.
I need my power meter......
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Old Apr 16, 2012, 08:40 AM
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Originally Posted by PeterVRC View Post
Max, you are talking about the wrong leverage things....
We (my outlines) are talking about having the required travels for full range of surface movement and THEN choosing what best holes to use for that.
For the equal travel range, whether you go outwards in holes, or inwards, the leverages etc remain identical.
As already stated, any increase in "source leverage" by using a further out hole is equally and oppositely offset by the decrease in leverage of the further out hole at the receiving hole end.

Your mention of one longer pole feeding a shorter pole has nothing to do with this.
That aspect is the part of working out what holes you need to GET your desired travel range. That will need certain distance and thus torque supply.... and that is a fixed factor then.
Ah well that's simply not true. Especially from the context from where this conversation started.

The conversation started with this model as;
Some saught to get a 3D responsive surface by using the outside servo arm holes. This is also show in the FW manual.
This allowed to achieve the full swing to end points without using the full swing of the servo. This becomes a part of this discussion where your variation in setup to get to the end points can demand the same force but increases the torque at the servo.
Doing so, high on the servo arm reduced the resolution and put more strain on the servo and got to the end point without utilizing the full swing of the servo.

I posted a picture demonstrating early on that the full swing of the surface wasn't using the full swing of the servo and if you went a little lower on the servo arm you could still get end points, reduce the torque requirement on the servo.

From there the Force=Torque/Dist speaks for itself. The hole you choose changes the torque exerted on that fulcrum, be it the Servo spindle or horn base. Its for this simple reason that for some reason you won't acknowledge that they have heavier horns and servo's on 3D models that in most all cases has the same size surface but only looks to move the end point a little further.
The force needed for more deflection goes up to some measure but the torque variance between the Servo to horn can quickly go up as the hole choices are made. And many as a default think for some reason that this must only be achieved by going longer on the arm.
Newman, Troy built Models and others say otherwise.

Funny..... Don't see how you conclude the two different poles have nothing to do with it since chosing the holes to get to the same end point is the conversation but one can do so either way changing the torque experienced atthe horn or the servo.
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Old Apr 16, 2012, 09:33 AM
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Quote:
Originally Posted by PeterVRC View Post
Just 2.2 Kg for vertical testing..... hmmm, something amiss somewhere it would seem. 2.1.... 2.2.... that is within tolerance of variation for tests, or even for horizontal testing to have loss due to drag.

The plane weighs 2.9Kg.... so 2.2Kg - even if it gets a bit better in the air - is not overly good.
I need my power meter......
really I was getting a lil over 2.8kg of thrust just shy of 2.9kg on gold power on a 5300 mah 6s.

Believe I was getting 2.4kg of thrust on a 4000mah battery, so maybe its your battery...?

http://www.rcgroups.com/forums/showp...postcount=1168
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Old Apr 16, 2012, 11:29 AM
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Weight and thrust

Hi there,

just as a data point for the thrust question: The version I build without gears, with skids only, weights about 1995 grams empty. With the battery, it weighs about 2700 grams. And I don't get 1:1. Hovering does not work.

Cheers,
Henrik
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Old Apr 16, 2012, 03:08 PM
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CG issues Pre maiden flight

Ok guys..

I got the Turngy 5000mah 30c battery installed to the most reward position possible and I am not close to 145mm.. more like 130mm..

My balancing method is crude as I dont have another way to do this.. but I marked the 145 to 165 range suggested throughout the thread( Post #9) .. translated those makes outboard on the upper wings.. I inverted the airplane over my head while balancing the airplane on my thumbs.. ( don't laugh) the balance point is well forward of the reference marks... I did use the correct reference datum of the wing attach to fuse point.

Did you have the gear extended? looks like I'll have to find a place to add some lead in the tail..

thanks for the eval... and sugestions...
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Old Apr 16, 2012, 04:07 PM
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Ya know, I'm looking at the CG picture in the instructions.. I'm comparing it to the panel marking in the model as well.. It looks to me that the CG datum is not the point where the wings attachs, but forward where the chine and wing start outboard from the fuse.. if thats the case, then I am probably ok, as this moves my CG marks forward about the right amount..

any imput on this .. if this is not right, then it looks like lead will have to be added to the rear somewhere.. and I hate that..
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Old Apr 16, 2012, 04:07 PM
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That's very odd. My battery is almost certainly heavier than yours (55C) and mine isn't even all the way back.

I did install the Rx rearwards of the battery bay, not sure if that made a difference.

I think only low wing warbirds need to be inverted for balancing. This jet can be balanced upright - I did anyways.

You should balance the plane with the LG retracted.
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