RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT   
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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/10/2003 11:47 AM   
inter


 

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Status: offline 		Frank,

That's pretty much my setup. I chosen the J'Tec over the bisson. Mainly due to the weight so it balances a little easier.

If your mail ordering your stuff (like I am), that's going to cover you well.

If you can get the fx running like the pros say without the pump, you can always sell the pump or pass it on to someone.

BTW, can anyone comment on the J'Tec pitts muffler. I know it has a cast muffler body (more weight), regardless, I'm thinking there's not a vast performance difference in the various (slimeline, bisson, J'Tec, etc) pitts mufflers.

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/10/2003 11:53 AM   
Simon Jones



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We'll have to see about that, after all it's only far that we win something once a decade.

I haven't seen much of the rugby but I saw some of the first half of Scotland game on Saturday, what did you think of the ref? Don't get me wrong, from what I saw Oz were the better side but some of those calls looked way questionable to me.

Silver Surfer

I'm sure someone else will answer the OS specific questions better than me, but you should only need to add the pump if you are going for a CoG mounted tank. I tried to do this and it caused all sorts of problems. My advice would be to go with the standard tank and position for the first few flights at least. This is a far less complex set up which means there's less likely to go wrong in those first exploratory flights. If once you have got the hang of the plane you feel that the tank position or capacity is a problem then go for the CoG tank with the pump. I'm rally mindful that adding a pump is an additional unneeded problem when you are trying to run an engine in. If you have a problem you won't know where it is with a pump set up. Without it you'll know where the problem lies.

Additionally I would recommed considering other engines. The Moki 180 might be a great unit. A lot of people are adding weight in the nose. If this is as much or more than the additional weight of a Moki you may as well get some use out of that weight. I'm sure the Moki will comfortably out pull the OS. You could also look at the MVVS 160 glow that I'm using. Being a european engine you will probably save some money. Mine was on special and cost about £150 (225 euros) with a pitts muffler. That's a big saving on an OS and has more power with less weight. The only downer is that the standard carb wouldn't run right with a CoG tank and pump set up. On the plus though you can convert this motor to Gas at a later date if you want.

Good Luck which ever way you go. Hopefully you'll get some more advice on the OS set up from someone who is using it.

sj.


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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/10/2003 2:35 PM   
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quote:



Will is be okay or did I miss anything??
Is there a difference in what screw I will use for getting the fitting installed?
Will the pressure connection from the muffler to the tank still be necessary??


I think you have it covered, I would order a tank that is between 16 and 20 oz

Use the upper left screw as viewed from the rear, remove the backplate, install the pressure fitting, stuff some paper towell-etc.., in the crank area to keep out metal shavings, select a drill bit equal to the ID of the pressure fitting and drill with the fitting in place. Then just clean and reassemble, takes 10 minutes.

No I plugged mine, there are three lines from the tank, a fill line, which is plugged, a vent line, and a pickup line going to the carb.

Mine balenced about 10mm behind the aft recommended point with no weight added(140mm), I think this will be ok based on TT2,s report at the first of this thread. I will post a final dry weight soon. I was dissapointed with the lateral balence, I had to add 1.2oz to the left wingtip.


Hope this helps

Dan

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/10/2003 2:41 PM   
Dangerous Dan



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Status: offline 		TT2,
You stated that your initial CG was 1/2" behind the recommended range and that you might move it further aft. How stable was the initial setting? How far aft did you move it? Mine is at about 1/2 inch or so behind the recommended range, should I be concerned, I am sure your piloting skills are stronger than mine. My battery is all the way forward. So to shift the CG forward I would have to add lead, I absouletly hate doung this it is like drivib=ng with the parking brake on.

Please advise.

All

I am almost there all I have left is programming the radio, adding decals, and running the engine in, I hope to get the maiden next Sunday.

Dan

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/10/2003 4:18 PM   
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Status: offline 		Simon,
Where did your CG end up after removing the extra pump etc....
Do you think you would be able to move it back?
Does it fly different on an empty tank?
Do you think 10mm behind the aft recommend cg is to far for the maiden?

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/10/2003 5:29 PM   
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Status: offline 		Frank, I'm not familiar with other engines, but if you use the OS 1.60 with a pitts muffler, you will most likely need a pump anyway, regardless of where the fuel tank is located. I'm using the stock tank right behind the firewall and on my first few runs, my engine would lean out half way through the tank, even with the needle valve open 3 1/2 turns. Apparently, pitts style mufflers (I have a Bisson) are not able to provide the kind of pressure this engine requires. It only seems to work fine with the stock muffler. As for the pressure tap, like Dan said, drill the upper left hole going through the id of the fitting (I used a 1/16" bit). Don't use the muffler's pressure fitting, it should be plugged. My 2 cents.

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/10/2003 10:44 PM   
TT2



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quote:

You stated that your initial CG was 1/2" behind the recommended range and that you might move it further aft. How stable was the initial setting?


The plane was very stable. Your only concern with this CG is the amount of elevator throw you are comfortable with. If you use the elevator throw per instructions on low rates you should be fine. Crank up the high rates / expo a little at a time...once again, whatever you're comfortable with.

quote:

How far aft did you move it?


I haven't had the chance to fly it much so I've left the CG where it was. Looks like additional experimentation will have to wait for warmer weather...bummer...

quote:

Mine is at about 1/2 inch or so behind the recommended range, should I be concerned, I am sure your piloting skills are stronger than mine.


Man, do I have you fooled! I didn't find the resulting CG to be much of a problem...the plane is still pretty easy to fly and will certainly be easier to land with an aft CG.

quote:

My battery is all the way forward. So to shift the CG forward I would have to add lead, I absouletly hate doung this it is like driving with the parking brake on.


I HATE LEAD! The only place I end up with any lead in a plane is in one wingtip. I have no idea what you're comfortable with, so if you want to add some lead to the nose initially to provide some peace of mind, there's certainly no crime in that. But...I think that you'll find yourself removing the lead within a very short time. I can only say what I'm comfortable with based upon my experiences, and I'm saying that the CG I ended up with should be resonable for any decent intermediate pilot. You know...the kind of guy who can land without bouncing 95% of the time and has owned (and still owns) a few low and mid-wing planes. All I can say is best of luck! I'm sure you can handle the Katana ...it's really easy to fly throughout it's flight envelope.

-Tom

< Message edited by TT2 -- 11/10/2003 5:48:46 PM >

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/10/2003 10:58 PM   
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Been meaning to say a big thank you for stating this thread. It encouraged me to go out and buy this model which has turned out to be one of the best I've ever flown. I really am chuffed with it, so thanks again for aking the time to start the thread.

Well I bit the bullit this evening and did the wing mods. I must admit that Dans method of opening every othe bay worked really well and it was prety easy to get everything in place and glued.

I've copied dan with the white stripes that should help orientation and get over the probelm of matching the red. Looks a lot bette for it, even with my dodgy covering skills(or rathe lack of).

The mods I did were to add sheer webs as far out as you can (2bays out after the servo bay, 6 bays per wing) and stengthened the last rib that thewing tube sits in a bit with some balsa laminated with the grain at 90 degs. What I would like to know is does this mean that I can really throw it about now? Will it cope with blenders, walls etc or will I still need o be midful of wing strength? Some fedback on how some of he other modded wings out there have coped would be very helpful.

Cheers.

sj.


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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/11/2003 1:54 PM   
Dangerous Dan



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Status: offline 		I am almost there I got the radio programmed with the exception of expo last night.

How much expo are you guys using?

I am using the hitec eclipse, so I have 4 flight modes, two switches. I dont like having seperate elevator, aileron, and rudder rate switches it is too much to remember.

flight mode 1 I am using the minimum mfg recommended throws

flight mode 2 I am using the maximum mfg recommended throws(a little extra on rudder)

Flight mode 3 is for 3d(45% elevator and rudder, 25% on aileron)

Flight mode 4 is just like flight mode three, but aileron is 35%

I will probably use flight mode 2 for the maiden, on the next few flights I will expierment with the other modes to determine what throws I need for precision aerobatics(IMAC), and 3D.
The result should be three modes, precision, 3D, and holy (*&% look at that thing roll.

Once I add the decals(special order I will post pics soon), and burn in the engine I will be ready for the maiden. I still need to get the final weight, wish me luck I am hoping for 10.5lb or less.


I was dissapointed that I had to add 1.2 oz to the left wingtip.

Did anyone else have to add this much weight for lateral balence?


Thanks to all who have helped me on this thread

Dan

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/11/2003 3:08 PM   
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quote:

Been meaning to say a big thank you for stating this thread. It encouraged me to go out and buy this model which has turned out to be one of the best I've ever flown. I really am chuffed with it, so thanks again for aking the time to start the thread.

You're welcome! I felt it was my DUTY to let others know about the excellent flying qualities of this plane as well as potential problems that need correcting. I should get a kickback from GSP! I'm chuffed with it too...I guess...whatever 'chuffed' means!

My wing is holding up well. I've done blenders, violent snaps, parachutes, etc, but haven't really tested the limits because I know what would happen if I found the limit!. CRUNCH! For 'sensible' flying the wing is strong enough. I'm sure that you could shed the wings by doing a full-throttle entry into an immediate blender or parachute, but that steps outside the bounds of what should be reasonably expected of this airframe.

Here's my radio (JR 10x) settings. Low rates are throws per the instructions and high rates are full surface deflection:

Elevator:
Low rate: 34%; 30% expo
Mid rate: 62%; 40% expo
High rate: 100%; 60% expo

Aileron:
Low rate: 30%; 30% expo
Mid rate: 60%; 40% expo
High rate: 100%; 60% expo

Rudder:
Low rate: 50%; 30% expo
Mid rate: 75%; 40% expo
High rate: 1000%; 60% expo

This probably isn't much help, but I had the radio in front of me at the time, so what the heck..

-Tom

< Message edited by TT2 -- 11/11/2003 10:55:00 AM >

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 1:59 PM   
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Status: offline 		here is som almost final pics, I still have to burn in the engine, set expo in the radio, get the dry weight, and add decals. I found some awsome patrotic decals, I will post some pics once they are on the plane.

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 2:00 PM   
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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 2:42 PM   
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Status: offline 		Dan that's looking great.

I'll keep my fingers crossed for you at the weekend.

I've now added a further mod. I found that I could only use about 70% throw on the rudder before the suplied servo horn extention bound on the fuz. Having had some imput from our resident hot shot, his view (not knowing the limitations) was that a bit more rudder would be good.

So I have made a wider extention from pre cured fiber glass laminated with carbon tows. I would have liked to do this with pre cured carbon but that is very hard to get hold of and very expensive here, so I had to "bodge it and leg it". This adds about 11mm each side of the standard extention, which gives more movement before the horns and conecting rods bind against the fuz. This has now given me 100% throw with no binding and a "square" geometry on the linkage.

Anyone else had this problem?

sj.


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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 2:47 PM   
Dangerous Dan



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Status: offline 		Simon,
I did not use the factory aluminum rudder horn for this reason, I used a nelson(formaly rocket City), aluminum horn, it was about 20mm wider than the factory one ald worked great, You may be able to see it in one of the pictures, with 100% travel on my servos the rudder almost touches the elevator halves.

Dan

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 2:48 PM   
Dangerous Dan



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Status: offline 		Bike 466,
Look at the closeup of the tail. This is the hex head wood screws I was telling you about, I used these for the hatches, servos, canopy, and cowell. A bag of 100 is around $7 from Dons Hobby Shop.

Dan

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 3:05 PM   
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Status: offline 		One thing to take note of here guys. The owner of the local hobby shop here (deals in Hitecs) told me NOT to run my Hitec Digitals at 100% throw because they are known to lock in that position. This came up when I was asking him to get me a programmer so I could max out the throw on mine for the Katana . Can't say for sure but he usually doesn't steer me wrong. I'm referring to 100% throw on the servo's themselves, not as dialed in from your transmitter. Hope I put it so you can understand. Hitecs will rotate about 190 degrees and I assume that he was referring to not causing them to drive a full 90 degrees from neutral.

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 3:15 PM   
Dangerous Dan



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Status: offline 		I heard about that also, but was told that was only an issue with early releases of hitec servos, Might be a good idea to e-mail hitec.

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 3:24 PM   
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Status: offline 		I see it now Dan. Sounds like we've got about the same set up, your con rods look very similar to mine too (just a bit neater).

cstevec.

Cheers for the tip. I'm set at 100% on transmitter. This is about 50deg each way so by the sound of things this should be fine. I take it your man was suggetsing that you do not programme the servos to 100% of their physically available travel.

sj.


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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 3:34 PM   
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is it the original landing gear?

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 3:36 PM   
Dangerous Dan



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Status: offline 		no the gear is from http://www.fiberlite.com it is made special for the Katana 140 and saves 5 oz over the mfg gear

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 5:21 PM   
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Status: offline 		Dntmn, when I tried to click on your link I didn't get to where I wanted to go ( I hope). Can you redirect me? I am really interested in aset of those for myself.

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 5:49 PM   
Dangerous Dan



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Status: offline 		csteve sorry its http://www.fiber-lite.com

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 5:51 PM   
Dangerous Dan



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Status: offline 		cstevec,

Here is a cut and paste from an e-mail reply from hitec concerning digital servo endpoints
quote:


Hello
This only occurred with the very first production of the digital servos with end points above 125%(the dates that were affected are listed on our web site). The pulse width was widened and there have not been any issues since.

Regards,
Brendan Lugo
Hitec RCD USA/ Multiplex Model Sports USA
Fax: 858-859-2618
Phone: 858-748-6948



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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 6:33 PM   
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Status: offline 		Appreciate the enlightenment my friend. I'm trying to make this plane the best it can be and also to eliminate all of the issues I can before it flies.

So far I have completed the hatch mods, sealed the inside of the plane using thinned finish epoxy, strengthened the engine mount and purchased the engine and servo's. I am commencing surgury on the wings tonight (which I hope will go quickly) and then will be mounting up the engine. After that it's all down hill!

Personally I have had only one Hitec servo failure and that one failed while burning it in on the bench, right out of the box. I use them in all of my planes and have been very satisfied with them. I have acquired enough of them over the last season to decide that a programmer makes sense. Before the Hitecs I used Futaba servo's but the cost and limited number of choices eventually drove me away.

Appreciate the update on the link. If it works, I'll be ordering a set of those gear, probably tomorrow. Since my engine wound up near 4 lbs. I am looking to shed weight wherever possible and the factory gear is HEAVY!!! If the wing loading comes out too high, I may wind up replacing the Roto 35 with a big Saito or a YS. Anyway, thanks again.

SteveC

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RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 11/13/2003 7:03 PM   
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Here is an article I wrote for our llub newsletter concerning engine thrust it might help

quote:

Thrust
Most manufacturers recommend some degree of down and right thrust when mounting the engine. There are several factors that effect the degree and direction of thrust needed. These factors are beyond the scope of this article and would need to be an article onto themselves. The best way to achieve the proper thrust angles is to mount the firewall with the recommended thrust angles built in. ARF planes are becoming increasing popular, and you do not have the option of changing the angle of the firewall in a prefabricated plane. Typically the recommended method for ARF’s is to place washers under the engine and/or engine mount to achieve the desired thrust angle. The problem with this method is, when you tighten the engine mount to the firewall you sink the washers into the wood, not to mention the addition of weight. The advantage of washers is the ease at which you can change the thrust angle. When initially setting up a new plane, particularly a precision aerobatics plane, the thrust angle may need to be adjusted for up-lines etc..I am currently building/assembling an ¼ scale Katana . The manufacturers recommended thrust was 2° right and 2° down. Here is how I achieved the recommended thrust angles without the use of washers. The plan is to grind the angles directly into the engine mount, the hard part is marking the engine mount so you know where to grind to. First mount the engine to the engine mount using conventional methods. Then use a caliper to measure the height and width of the mount. Next apply a little Trigonometry to these measurements, here is the formulas:

( Look below for the formula it wouldn't paste from word)


Legond:

H= Height of engine mount
W= Width of engine mount
L1=Down thrust mark
L2= Right thrust mark
θ1=Degrees of Down thrust desired
θ2=Degrees of Right thrust desired
L3=L1 + L2

Once you have determined the values for L1 and L2 you are ready to scribe your engine mount. As viewing the engine mount from the rear mark the length L1 into the lower left corner of the mount. Mark the length L2 into the upper right corner of the mount. Mark the length L3 into the lower right corner of the mount. With a straight edge scribe the mount between these marks. From the lower left and upper right marks scribe to the upper left corner itself. You should now have lines scribed on all 4 sides of the mount. Wrap your engine in plastic leaving the mount exposed to protect the carburetor and muffler area from particles created when grinding the mount. Use a belt type sander with coarse grit paper to grind the motor mount down to these marks. Bolt the engine to the firewall, and the engine will have the desired thrust angles.

If you do not have access to a caliper you can use a protractor and make a cardboard template.

If after test flying the new plane the thrust angle needs further adjustment you can use washers, at the field, for a temporary fix. When the plane is back in the shop you can transfer the angles achieved from the washers to the mount, utilizing the methods mentioned above, for a permanent fix. Hope this helps.

Dan Powell


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All Forums >> RC Airplanes >> ARF or RTF >> RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT
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