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Katana 50 by Hangar 9

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Katana 50 by Hangar 9

Old 04-25-2013, 03:45 PM
  #101  
MThemadhatter
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Default RE: Katana 50 by Hangar 9

I had a look at the servo elevator mounts and picked up a couple of A5040's for the elevator. I think the 5945's would have been to deep to fit
Old 04-26-2013, 01:41 AM
  #102  
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Default RE: Katana 50 by Hangar 9

I had a think last night and also looking at this motor [link=http://www.giantshark.co.uk/epower-gt4020-470kv-280g-brushless-motor-p-405962.html]GT4020-470[/link] as a sort of halfway house between the two. I already have two of the 620Kv version of this motor for a beufighter that I am slowly building.

One thing I am trying to find out is the dimension of the E-Flite Power52 that is recommended on the box.
Old 04-26-2013, 07:35 AM
  #103  
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Default RE: Katana 50 by Hangar 9

I think the Power 52 would be pretty good on 5S and a 15 or 16" prop; it'd probably be a little "hot" on 6S and would have to use a smaller prop, like 13 or 14", as I do on my Value Hobby 600kv motor. The Power 52 shows an overall diameter of 50mm, and weight of 346g, so I'm guessing it's pretty close in size to the 5055 motors we've referenced.

I did get to fly this exact plane last summer at a local flyin; owner was a "glow" guy and made the mistake of buying the Power 60, because, of course, a 60 is better than a 52, right? He was running it on 5S 5000mah packs and a 15" prop, and it was a complete turd, as far as 3D. I told him it needed the Power 52 on the same prop, and about 3300-4000mah packs for less weight and more power; he put a DLE20 on it instead and promptly crashed it...oh well.
Old 04-26-2013, 04:23 PM
  #104  
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Default RE: Katana 50 by Hangar 9

I'm still thinking that a Axi 4120 with a 5S is the way to go - mainly because that's what I have to put on it. I might try a 14x8 or a 13x8 3-blade prop


Has anyone use the 'templates' that came with the kit for mounting the motor/engine? Mine don't seem to line up all that well with the holes drilled into the backplate of the electric motor mount.

Just asking.....

Bob
Old 04-27-2013, 04:23 AM
  #105  
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Default RE: Katana 50 by Hangar 9

I have been flying RC for 5 years and have 10 planes, of which four are Hangar 9 products (Twist 40, Funtana 125, Spitfire 60, and Katana 50). My favorite of these three is the Funtana 125 powered by a Saito 125, which flies superbly and now has well over 100 flights. On the strength of this I bought a Katana 50 and powered this with a Saito 82. I put this together very carefully and used superior Dubro parts for control linkages and push-pull for rudder, and used exactly the servos you recommended, e.g., Spektrum 6060's for the ailerons. The engine was fully run in before mounted on the plane and runs very smoothly; there is very little vibration compared with my Saito 125 on the Funtana 125. I also set up the servos on the Katana exactly as per the manual with the rates that you recommend, even though this necessitates very bad mechanical "disadvantage" between control horns and servo arms. All this is to pre-amble to my expectation that the Katana would fly very well. This is what happened:
Flight 1: Flew perfectly off the ground and required very little trim adjustment. I flew it round at about half throttle, like a trainer, and did a stall test. About 4 minutes into the flight the left aileron suddenly flew off, which totally took me surprise, but I was able to land the plane immediately and very gently. The aileron looked as though it had been wrenched off very hard, since the fibre hinges had been ripped off with the surrounding balsa.
Flight 2: With aileron repaired, I flew the plane again a few weeks later. The plane needed retrimming, then suddenly again at about the four minute mark the plane wallowed a bit, so I landed it immediately (again very gently) and found that one of the elevator push-rods had come detached, even though I had checked that it was really tightened down hard just a few minutes early.
Flight 3: With everything double checked, I expected third time lucky. Again, I flew the plane round at about half throttle, only going to full throttle for one or two verticals ending in stall turns. I did a few gentle loops and rolls, I think still on low rates. Again at about the four minute mark (!), I was flying the plane straight and level at about half throttle when all hell broke loose. An aileron stripped off and various other apparent debris (one piece was a wheel spat that when retrieved appeared to have been wrenched hard off the plane!). Yet again I was able to make a gentle emergency landing. I was lucky to get it down because one aileron was missing, both aileron servos were completely stripped (i.e., I had landed on rudder and elevator only without knowing it), and the port wing with the missing aileron was cracked right across the chord just outboard of the wing tube, and the opposite wing was also slightly cracked. I must have cut the power just before the wing failed completely. In this last incident there was a loud fluttering noise, so this was a clear case of flutter, probably of the ailerons, but possibly also the wings. The entire destructive episode could not have lasted more than one or two seconds, but the damage it did in that time was incredible.

I stripped the covering off both wings, and the more seriously damaged one practically fell apart in my hands. It is clear what the problem is: although the Katana wings look very well made (from the outside) they are very weak. The main spar is notched half way through at every rib, creating a very weak point where the wing tube ends. Also, the way the instructions tell one to set up the aileron servos with long servo arms and the pushrod connected to the second innermost hole on the aileron horn. Is mechanically very weak for such a large control surface with such big throws. This combined with the weakness of the wing was undoubtedly the cause of the flutter. Also, the rear spar that takes the aileron hinges is only about a quarter of an inch thick, which is not really enough for holding the hinges securely.

So the problem is not one of equipment or manufacture, but bad design. I would say this is the reason Hangar 9 have withdrawn this model. The Funtana much have a much stronger wing construction, because mine has survived vigorous aerobatics over three years without falling apart.

I am rebuilding the wings at the moment, including carbon fibre bracing spars, and adding blocks for the hinge mounts . Already the wing is probably about ten times stronger than the original.

For all of you who have Katana 50's, I would suggest that you might strip the covering off the wings and beef them up as I have done, before the plane breaks up on you.




Old 04-27-2013, 04:26 AM
  #106  
John Stainforth
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Default RE: Katana 50 by Hangar 9

I have been flying RC for 5 years and have 10 planes, of which four are Hangar 9 products (Twist 40, Funtana 125, Spitfire 60, and Katana 50). My favorite of these three is the Funtana 125 powered by a Saito 125, which flies superbly and now has well over 100 flights. On the strength of this I bought a Katana 50 and powered this with a Saito 82. I put this together very carefully and used superior Dubro parts for control linkages and push-pull for rudder, and used exactly the servos you recommended, e.g., Spektrum 6060's for the ailerons. The engine was fully run in before mounted on the plane and runs very smoothly; there is very little vibration compared with my Saito 125 on the Funtana 125. I also set up the servos on the Katana exactly as per the manual with the rates that you recommend, even though this necessitates very bad mechanical "disadvantage" between control horns and servo arms. All this is to pre-amble to my expectation that the Katana would fly very well. This is what happened:
Flight 1: Flew perfectly off the ground and required very little trim adjustment. I flew it round at about half throttle, like a trainer, and did a stall test. About 4 minutes into the flight the left aileron suddenly flew off, which totally took me surprise, but I was able to land the plane immediately and very gently. The aileron looked as though it had been wrenched off very hard, since the fibre hinges had been ripped off with the surrounding balsa.
Flight 2: With aileron repaired, I flew the plane again a few weeks later. The plane needed retrimming, then suddenly again at about the four minute mark the plane wallowed a bit, so I landed it immediately (again very gently) and found that one of the elevator push-rods had come detached, even though I had checked that it was really tightened down hard just a few minutes early.
Flight 3: With everything double checked, I expected third time lucky. Again, I flew the plane round at about half throttle, only going to full throttle for one or two verticals ending in stall turns. I did a few gentle loops and rolls, I think still on low rates. Again at about the four minute mark (!), I was flying the plane straight and level at about half throttle when all hell broke loose. An aileron stripped off and various other apparent debris (one piece was a wheel spat that when retrieved appeared to have been wrenched hard off the plane!). Yet again I was able to make a gentle emergency landing. I was lucky to get it down because one aileron was missing, both aileron servos were completely stripped (i.e., I had landed on rudder and elevator only without knowing it), and the port wing with the missing aileron was cracked right across the chord just outboard of the wing tube, and the opposite wing was also slightly cracked. I must have cut the power just before the wing failed completely. In this last incident there was a loud fluttering noise, so this was a clear case of flutter, probably of the ailerons, but possibly also the wings. The entire destructive episode could not have lasted more than one or two seconds, but the damage it did in that time was incredible.

I stripped the covering off both wings, and the more seriously damaged one practically fell apart in my hands. It is clear what the problem is: although the Katana wings look very well made (from the outside) they are very weak. The main spar is notched half way through at every rib, creating a very weak point where the wing tube ends. Also, the way the instructions tell one to set up the aileron servos with long servo arms and the pushrod connected to the second innermost hole on the aileron horn. Is mechanically very weak for such a large control surface with such big throws. This combined with the weakness of the wing was undoubtedly the cause of the flutter. Also, the rear spar that takes the aileron hinges is only about a quarter of an inch thick, which is not really enough for holding the hinges securely.

So the problem is not one of equipment or manufacture, but bad design. I would say this is the reason Hangar 9 have withdrawn this model. The Funtana much have a much stronger wing construction, because mine has survived vigorous aerobatics over three years without falling apart.

I am rebuilding the wings at the moment, including carbon fibre bracing spars, and adding blocks for the hinge mounts . Already the wing is probably about ten times stronger than the original.

For all of you who have Katana 50's, I would suggest that you might strip the covering off the wings and beef them up as I have done, before the plane breaks up on you.




Old 04-28-2013, 09:11 AM
  #107  
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Default RE: Katana 50 by Hangar 9

Could you post up some pictures of your fix ?

Mean while trying to decide which power set up to go for I have done what I always do when stuck, make a spread sheet !

For 5cell the wieght is based on a 5Ah Battery and 4.5Ah for 6cell. The capacity for 8min is based on the current draw at 70% throttle. The watt/per pound is for the total wieght. I think 6 cell is the way to go. The weight difference is not a lot.


5cell

Weight Motor Prop Esc Battery Total Weight Current WOT Capacity for 8min Watt/Pound
5055-580 290 15x7 100 659 1049 71.5 6.0 192
4020-620 280 15x7 100 659 1039 75.5 6.3 203

6cell

Weight Motor Prop Esc Battery Total Weight Current WOT Capacity for 8min Watt/Pound
5055-400 290 16x8 100 676 1066 54.3 4.5 170
4020-470 281 16x8 100 676 1057 61.5 5.1 192
Old 04-28-2013, 09:17 AM
  #108  
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Default RE: Katana 50 by Hangar 9

Hmm that did not work, so in summary lol

5cell 71A at wot 1.04Kg power system wieght, and would need a 6Ah battery to fly round for 8min at 70% throttle 192W/lb
6cell 55A at wot 1.06Kg power system wieght, and would need a 4.5Ah battery to fly round for 8min at 70% throttle 170W/lb

The capacity calculation is based on using 80% of the batteries capacity. Calculations where done using results from motocalc and are probably rough
Old 04-29-2013, 12:42 AM
  #109  
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Default RE: Katana 50 by Hangar 9

I am currently away from the plane, but I will send you some photos of the fix within about a week, together with a list of the modifications I have done. After that, I will be interested to see (a) how much heavier it is than before, and (b) how it flies. So you had better hold off copying what I have done until I have proven I can still get the plane off the ground (only joking!)
Old 04-29-2013, 04:02 AM
  #110  
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Default RE: Katana 50 by Hangar 9

I have just started going through the small parts in mine and I want to replace the plastic clevis. I had some 2-56 sulivan clevises but these are to small for the included push rods. Does anyone know what size they are ?

The imperial stuff is harder to come by in the UK so it would be good to know before ordering some bigger ones ?
Old 04-29-2013, 05:11 AM
  #111  
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Default RE: Katana 50 by Hangar 9

I replaced mine with DU-Bro 2mm ball clevises and they fit the included pushrods. They are a little shorter than the included clevises. They worked okay on both ends of the aileron pushrods but had very little thread engagement on the elevator pushrods so I used the included nylon snap clevises on one end and replaced the ball end on the other.

I added some black and white "swoosh" panels to the red and yellow on the underside of the wing for more contrast. It could still use something more distinct in my opinion.

Had several flights with mine over the weekend and I'm really enjoying it.

Jaybird
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Old 04-29-2013, 03:20 PM
  #112  
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Default RE: Katana 50 by Hangar 9

Looks good in the air

I had another look at my rods and there not 2mm or 2-56, they are either 2.5mm or 4-40 , anyone know for sure before I spend my money on some clevises ?
Old 04-30-2013, 01:25 AM
  #113  
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Default RE: Katana 50 by Hangar 9

Ok I have measured the rods this morning and

On the main shaft they are 2.04mm and the thread width is 2.3mm I am going to pop into my LMS and see if I can find a clevis that fits

Now all I have to do is decide on which motor
I have 3 to choose from the


[link=http://www.giantshark.co.uk/xyh5055-400kv-brushless-outrunner-p-403284.html]EMP 5055-400Kv[/link]

[link=http://www.giantshark.co.uk/epower-g...-p-405978.html]GT4030-420Kv[/link]

[link=http://www.hobbyking.com/hobbyking/s...dProduct=37209]Aerodrive SK3-5055-430Kv[/link]

They weigh 290gr / 380gr / 380gr wich is lighter or the same weight as a Power52

The EMP motor seems almost to cheap, out of these which would you go for ?
Old 04-30-2013, 07:28 AM
  #114  
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Default RE: Katana 50 by Hangar 9

What servos are you planning on using in the tail? If bigger/heavier than minis (i.e. Hitec 225mg size), you'll probably want the heavier motor to help balance. If it were me, I'd go with the lightest setup possible, as the plane already is on the heavier side for a 60" plane...

Also, forgive me, as I don't remember what your planned usage is for the plane, but what kind of flying do you intend to do? If it's 3D, definitely go for the lightest motor/battery/servo setup. If it's general sport flying (sounds like it, with your intended 8min, 70% power flight times), I think it'll do fine with whichever setup you decide...
Old 05-03-2013, 10:46 AM
  #115  
John Stainforth
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Default RE: Katana 50 by Hangar 9

Here are a couple of pictures of the carbon fiber braces I have added to strengthen the wings of my Katana 50.
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Old 05-03-2013, 10:51 AM
  #116  
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Default RE: Katana 50 by Hangar 9

The mods I am making to the wings of my Katana 50 are as follows:
(1) Add carbon fiber brace behind main spar, epoxied in, as shown in picture
(2) ditto to part of rear spar
(3) Add balsa blocks on either side of slots for aileron hinges (just visible in the photos)
(4) Add pinned-hinges (Great Planes medium nylon) epoxied in
(5) repair LE sheeting
(6) possibly add some 24 g/m2 glass fiber cloth to some parts of the LE balsa sheeting.
Old 05-16-2013, 09:54 AM
  #117  
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Default RE: Katana 50 by Hangar 9

I finally flew my strenghtened Katana 50 today, after doing all the repairs listed (1) to (6) above. Plane flew really well and withstood all the aerobatics I could throw at it without any problems. Surprisingly, the plane is the same weight as it was before the strengthening (6.75 lbs), which surprised me. Perhaps the new servos are slightly lighter than the previous. Anyway, the new wing is vastly stronger than the old, without apparently any weight penalty. So the fix is highly recommended, although it does involve quite a few man-hours (probably took me a total of 15 to 20 hours).
Old 05-25-2013, 04:13 PM
  #118  
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Default RE: Katana 50 by Hangar 9

Sorry you had to go through all of that, but it sounds to me like you were the victim of good old flutter.

You touched on mechanical advantage regarding the servo horn vs control horn, etc. I believe that is your problem, or else those JR servos aren't strong enough. I'm not familiar with the current JR/Spektrum line up, so I don't know.

My point here is, with those huge control surfaces this model has, if one reverses the mechanical advantage then that is pretty much a guarantor of flutter somewhere down the road. We know how destructive flutter is; sounds to me like you were lucky that the covering held the wing together long enough to get it down. There are few wing structures that could hold up unscathed to the severity of flutter that you described. And there is darn sure nothing wrong with the kit-supplied linkages. Good, stiff 2mm pushrods with excellent ball links and clevises.

Again, I am not directly criticizing what you did, or your observations... with one exception. I don't believe there is anything "badly designed" about this model. The designer has a bunch of successful designs to his credit, and this isn't the first one of those I've flown.

Anyway... hope it holds together for you; it is a superb-flying model when flown IMAC style. I cannot comment on its ability to flip-flop around, since I cannot fly that stuff.

.
Old 05-26-2013, 01:50 AM
  #119  
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Default RE: Katana 50 by Hangar 9

Many thanks for your insights re the flutter, which certainly wasn't good but I am hoping it's old.

The mechanical advantage I had was highly detrimental and I believe you are right in saying that it was the instigator of the flutter. The main point I would make is that I set this up exactly as per the Hangar 9 instructions, using new servos of the make and model that they recommended. I think it is highly likely that anyone else foolish enough to do the same will have the same problems. Hangar 9 should change their instructions.

Yes, I was incredibly lucky that my plane didn't break up in the air. I shut the throttle the moment I realised there were big problems, probably within about a second of the flutter starting. I think another tenth of a second would have been enough to destroy the plane. The force required to break the wing completely beyond the point it had got to would have been relatively minor. These forces were fairly incredible: enough to break servo arms, rip off an aileron, break the wing and strip two servos completely, in one or two seconds.

I agree that the plane is not really badly designed (I bought this on the strength of my satisfaction with previous Hangar 9 planes, including a Funtana 125 that has withstood all the aerobatics I have thrown at it over a three year period), but there is weak point in the notched main spar at the position of the end of the wing tube. This was not helped by rather inferior glue holding the rib there to the spar.

Anyway the plane is now flying very well (see attached, showing my improvised new colour scheme) on wings that are vastly strongly than the original. Yesterday, I really put the plane through its paces and there is absolutely no sign of any strain.
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Old 05-26-2013, 08:31 AM
  #120  
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Default RE: Katana 50 by Hangar 9

I have finished putting mine together and she has flown

In the end I went for the GT4030-420Kv on 6cell with a 4.5Ah battery and 100A esc

The threaded rod is its own size so I replaced them with carbon push rods.

It has more than enough power on a 15x8, specs say up to 16x10 with that motor but it's more than powerful enough with the 15x8. This is a very slippery airframe compared with my funtana and after a 10min flight I only put 2200mAH back into the lipo charging it after the flight. So I am thinking that a 4000mAh battery would be fine for 10mins











Old 05-28-2013, 10:16 AM
  #121  
LSP972
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Default RE: Katana 50 by Hangar 9


ORIGINAL: John Stainforth

The main point I would make is that I set this up exactly as per the Hangar 9 instructions, using new servos of the make and model that they recommended. I think it is highly likely that anyone else foolish enough to do the same will have the same problems. Hangar 9 should change their instructions.
Perhaps... but the set-up shown in the manual is a typical 1:1 3D set-up; IOW, the distance from the servo output shaft to the center of the ball link is the same as the distance from the control surface to the hole where the clevis attaches. Sometimes referred to as "linear", or "boxing up the system" (which means the four points of contact- servo output shaft, control surface hinge line, two pushrod connection points- in a given control surface/servo represents a parallelogram), this ensures maximum throw consistent with not overloading the servo.

When I mentioned "reversing the mechanical advantage" I was talking about some folks' habit of using the farthest point on the servo arm and the closest (to the control surface) hole on the control horn. This gives max possible throw... and also gives the control surface more leverage that the servo arm. Combine that with large surfaces and flight loads- sometimes referred to as "blow-by" - and unless you've got a big-nut servo, it will likely be over-powered/stripped during strenuous aerobatics.

You say you used a servo as called for in the manual. Assuming your linkages were proper (no slop) and the aileron hinge lines were sealed, that pretty much narrows down the possible culprits. To me, it says either a weak structure or weak servo. So you may be right. But I don't recall any other complaints of this nature from others flying this model. Nor have I heard any gripes regarding this issue from folks I know flying other, similar H9 models with the same sort of set-up... specifically, the 27% Extra 260.

Now, the original Funtana did indeed have a weak wing structure. Please do not think I'm casting doubts on your situation. I just take exception to your categorization of one incident condemning the whole line.

Its a moot point, in any event. This model has been discontinued; probably because it was priced $50 higher than the similar bamboo specials in the latest Tower flyer. I have over 30 flights on mine now, and have been impressed with it from Day One; particularly the quality of the hardware and kit goodies.

I am by NO means a cheerleader for Horizon; I've had my issues with them in the past. But it has also been my experience that the Hangar 9 brand of ARFs (at least, the ones I have seen) has always been of top quality. The SeaGull line, not so much.

I'm just glad I was able to score another one of these kits NIB. When I eventually kill mine, I'll immediately assemble the other one.


.
Old 05-29-2013, 02:19 PM
  #122  
John Stainforth
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Default RE: Katana 50 by Hangar 9

Actually the aileron set-up in the manual (which I used) does not look like 1:1 (see attached), and is very different to the recommended set-up on the Funtana 125, which has the control horn distance about 1".

In fact, the manual recommendation for the Katana 50 is pretty much the "reversing the mechanical advantage" you describe in your second paragraph.

There was no slop in the linkage, but the hinge-lines were not sealed, because that was not called for in the manual (another difference from the Funtana).

My Funtana seems to be perfectly fine structurally. It looks and feels 100% after three years of usage. I did *not* condemn the whole line. I bought the Katana because I like the Funtana so much (in fact it is my favorite plane). And I am perfectly happy too with my Hangar 9 Spitfire and Twist 40 (I have had three of those). The only Hangar 9 plane that I bought and I don't like is the Tango, which I don't think I mentioned before.

I bought this issue to the attention of this forum because it seems that every other Katana 50 that is set up exactly as described seems logically doomed to break up in the air at modest speed, assuming the wood and glue quality is similar. I wondered in my previous posts if that was the reason the model has been withdrawn so quickly. In the British aeromodelling press this was advertised with great fanfare in February's RCM&E (as a "new" product) - by April it was discontinued!!


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Old 06-02-2013, 04:47 PM
  #123  
LSP972
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Default RE: Katana 50 by Hangar 9


ORIGINAL: John Stainforth


In fact, the manual recommendation for the Katana 50 is pretty much the ''reversing the mechanical advantage'' you describe in your second paragraph.

I went back and looked at my manual, and indeed you are correct in regards to the aileron servos. The suggested elevator set-up is not as "radical".

Since I'm using servos far stronger than those called for (they came out of a 30% gasser), and my linkage set-up is an IMAC style (reduced servo throws via a small servo horn), and I sealed my hinge lines as a matter of course, I expect no such flutter issues on my model.

If I were you, I'd seal my hinge lines as well. All that beefing up you did will be to no avail if the aileron flutters as a result of surface blow-by and wrecks your servo. No, this wasn't called out for in the manual; but my kit included several strips of transparent adhesive-backed material for that purpose. I always use clear UltraCote or MonoKote for this chore, however.

At any rate... good luck with your model. I thoroughly enjoy mine.

.
Old 06-03-2013, 07:36 AM
  #124  
John Stainforth
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Default RE: Katana 50 by Hangar 9

Yes, I have sealed the hinge lines. As a result of this experience with flutter, I am
(1) Never going to have mechanical advantage worse than 1:1 on any control linkage.
(2) Always going to seal hinge lines
(3) Going to use pinned hinges instead of fiber.

My next plane is going to be scratch built, and it will probably have some carbon fiber strengthening.

Thanks for you good advice on mechanical advantage etc.
Old 06-06-2013, 08:10 AM
  #125  
badazzgti03
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Default RE: Katana 50 by Hangar 9

Anyone interested I have a Katana 50 for sale w/ OS91 $250

http://www.rcgroups.com/forums/showthread.php?t=1888226

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