i have a question on my GSP Katana,
anyone has one that can give me some input on CG. >?
it gives you a measurement (and that is what i will do) 100-125 mm from leading edge.... but at 125 mm it ends up and the front edge of the wing tube (aluminum one). i would think..... that the CENTER of the wing joining tube would be the balance point or "true " CG...
any input would be great... or hopefully some personal experience(with this ARF kit)

i am getting closer.... to being done and was just doing to much thinking,...heh

still have some issue`s to work out with this engine.. but ..i am getting there... slowly!...



another

I have about 20-25 flights on mine with the CG at 125mm. I have flown the plane teetering at that point and slightly nose heavy, it seemed to handle about the same to me. What engine is that you are using it looks awsome! I had the Saito 180 in mine and now it has an RCS 180 (hven't flown it yet with the gasser). What is the weight with your engine? Mine was very heavy but it still flew great, its lighter with the gas engine.

well....... i have not weighed it yet (whole plane ) but i think the engine is is the 35 oz range its an FT-120 OS™ i, i have this feeling i am going to be close on CG... may have to add some weight to the nose....
just hoping this wont be way under powered...(if it is i will switch engine out to a Moki™ or something),, i have a friend that will sell me either a 1.8 or a 2.somthing for a decent price and both are in decent shape.

but i had this engine for a while ...new in the box.. and have been wanting to put it in something. so here i go....we will see i guess..
i have a few issue`s.. to resolve yet.. exhaust being one of them ... may have to exit it out the sides of the cowl... may look cool running though.. but dont know about sitting there on the ground.

took a little doing to get it in right place(engine) to get it where i wanted it in relation to cowl and fuel tank...(has a 22oz tank,now)

thanks for input on CG. ill start at 125mm....(even though ill never prolly run it empty with tank i have,.and its in the front,,in nose).so it will be nose heavy when full...

guess i could balance it with 1/3 of a tank in it..at 125mm

here is another closer shot


not done routing hoses and wiring yet.

If it needs weight in the nose to balance, rather than add lead to the nose you might try pulling the rudder servo and mounting closer to the CG on a pull pull. I mounted my tank over the wing tube, the Saito 180 had no trouble pulling fuel (without a pump). Please let me know how that flys with that engine. Twin four strokes sound so good.

well. good to hear it pulled fuel from tank from where you had tank....i was going to try that but i was worried this twin does not even use a pressure nipple.(so they tell me) so i kept tank in front to give it all the help i could..

and yes i thought about moving rudder servo......1.9 oz in the back seems like a lot. i guess if and when i get close.. if its tail heavy i could just remove servo (in rear) to see how things end up(balance). but i do not look forward to moving it ....if i need to..
i crack up every time i hear "ARF" should be MORE LIKE "BETTER THEN BUYING A BOX OF WOOD" heh...
the little ARF`S .40-.60 are easy. but this big ones i spend some time on it seems
i will keep you posted on how it does.... this is my first "twin" as well

thanks for input

I ordered mine on last Thur, I plan on using a Saito 180 on mine also. Bike did you mount the Saito sideways or inverted? I'm considering inverted to keep from cutting the side of the cowl.

I mounted mine inverted, I only had to do minor trimming around the bottom of the cowl. I think it looks much better than having the valve covers sticking out the side of the cowl. Just don't forget to take off your glow igniter. Its kind of out of sight out of mind on the bottom of the cowl. I can't count the number of times I flew with it attached.

RC_SPORT, click on my gallery button you can see a nose on pic with the Saito 180 mounted inverted with the cowl on.

bike..... did you trim canopy around outside edge>? from the white line .outwards>? trim at white line.? pic was hard to tell.

cool looking lil dash guage strip... you painted it black under the canopy?... mine is grey

I left the white on (trimmed from the white out) and attached the canopy with some blue automotive stick on striping I got from an auto parts store. The striping is very flexable comes in almost any color and keeps the fuel out. I looks 100% better than screws.

The instrument panel you can download off the AMA website (from their project extra) it is an actual photo from a real Extra downsized. Best of all its free, I can also e-mail it to you if you want to give me your direct e-mail address. I didn't like the all grey area under the canopy so I took a piece of stick on black Monokote and attached it but left about 1/4 inch of grey on either side to make the cockpit look more 3D. My plane also has a pilot figure now.

you can email me at [email protected] . that would be cool. free is good

i was going to glue my caonpy on with glue.. once screwed...i am not real worried about seeing screws but that is a good idea.

cool.... trimmed at edge of white.... i was thinking that as well. the instructions were "vague" to say the least... for the most part in this kit...
i am used to a book of sorts and then a quick reference sheet . like this kit calls the instructions.

i was going to put some Jack-In-The-Box™ antenna balls for pilots in mine..

only thing i wished i would of done was put fuel tank on CG... <not in nose>.....balance it empty then fly nose heavy most of the time does not thrill me..... but oh well(was not sure motor would like it that far away is why i did that)

bike, thanks for the pics, I'm definitely going inverted.

One thing I forgot to mention, if you are going to mount inverted you need to mount the tank over the CG or atleast back out of that conmpartment. With the Saito the tank needs to be mounted at or below the spraybar on the carb at the rear of the engine, if not it will flood. With the tank in the stock location gravity will siphon you fuel down to the carb and you will most likely have a flooding problem (I did). An easy fix is to loop a long rubberband around the wing tube and the supporting wood and mount you tank on top the wing tube (approx around the CG) loop the rubber band ends around the front and rear of the tank to hold it in place. Because of the angle sloping downward from the nose to the tail, the level of the tank at the wing tube is lower than if its mounted in the nose. Cured my flooding problem. I tried an oscilating Perry Pump before that and it kept the engine from flooding with the tank located in the nose but I couldn't get the engine to run as well as it did without the pump. The Saito 180 does not need any help pulling fuel from the wing tube area anyway.

One thing you guys are going to find if you haven't already is the access hatch in the bottom of the fuselage is too small and a real pain to get at the wing springs. I have seen a thread where a guy installed a top access hatch, he did a great job but it looks like a lot of work and then you have the line for the top hatch where it is cut (which I didn't like). I chose the easy solution I made the bottom hatch longer and eliminated some of the hold down screws(6 screws takes too long to put on and take off and i think fewer to lose is better) to hold the hatch on by making the front of the hatch secured by a piece of overlapping light ply.

While on the subject of wing retention, be sure to use the wing bolts provided along with the blind nuts that go in each wing to hold the wings on in addition to the springs. I talked to a guy not too long ago who didn't notice in those clear instructions they provide that there were bolts and springs, he was just going to fly with springs (I think he would have had a lawn dart if he did).

bike, thanks for the info, one more thing, what size fuel tubing did you use?

Elmer, your pics look like the twin fits entirely within the cowling; am I seeing right (no cowl trimming)?

yes it fits inside.... all of it... i will get some photo`s of front.... carb inlet sticks out a bit under prop....... but if i did it again i would extend firewall(boxed area) another little ways......i extened it about 7.5 - 8 mm then shortened the cowl a little.
i need to do something with exhaust ,,,, has short little header pipes...may put holes in the sides(of cowl) and exit them even with sides like an ole warplane..... not sure.

then after reading some posts here ...i may have a siphon issue....tank is a bit higher then i wanted in relation to carb inlet...

i will do my best to keep things posted on here.

elmerfud
re:fuel tank
I have a Gemini FT-160 in my Cub, so the tank is lower than the carb, but the engine sucks so well that I think moving the fuel tank to the wing tube would probably work just fine. At worst, you could always add a pump, or move it forward. I love the engine! And, thanks for the reply on the engine/cowling question.

Geez...I can't wait for mine to get here. I ordered it about a month ago from Chief. I plan on trying a 1.60fx initially. With this setup I'll probably have to put the rudder servo at the CG which is fine with me. If the power isn't there then I'm going to slap on a ZDZ40RV. This plane should be awesome!

Are the elevators and rudder double beveled?

-Tom

SVFlier
thanks for info..... i fly at AMPS most of the time but i like your field better.... just to far of a hike for me.

hmm i wished i knew this engine sucked fuel as well as you said... i would of done different..i could invert engine..(i would have to move throttle servo again)

ever tried that with your 160>? (mount it inverted)

and you run no pump or pressure tap on exhaust on your 160>?

Yes, rudder and elevator are double beveled and all tail surfaces are airfoiled.

elmerfud:

No, I never thought of inverting it, but I don't know why it wouldn't work just as well.

That's right, No Pump, No Pressure Tap; I was worried at first, but not now.

The only thing I had to do for the installation was to space the engine a bit off the firewall, to meet the cowling, and to add the on-board ignition (comfort) system.

Oh yes, I started out with a 16x8 (I think it was) but changed to an 18x6-10 Zinger on the advice of a friend who has flown FT-160s for over 20 years; he was right, that is the optimum prop for this engine.

SVF

well cool.....i tried inverting one i have... just wont work out with cowl.... and exhaust . and carb inlet.... not practical..... i will have to see if it floods.... then if so......go from there. i could use a perry style pump.... it would act like an anti-siphon..(just an idea)moving the tank.....would be quite an undertaking in this plane......not to user friendly through access hole

i am curious on props i have a 16x6 and a 16x8. i was going to try...(remember mine is a 120 not a 160..<older,new in box..,but older . now they are 160`s)

maybe you could ask your friend or let me know if the 120 could take the same prop...or should i stick to the 16x6 or 16x8....(try them).......or just bump up to the 18x6

i thank you for all the input

chris

FT-120

No, I suspect that 18x6-10 will be too large for the FT-120. I think that you will more likely have to go down from 16x8 rather than up. I am running a 15x8 on my Saito 150.

I've had mine since Toledo. Still not done with it, but that is due to my laziness and I didn't like how you had to access the inside of the plane. I've cut the top deck off from the back of the cockpit fwd to the fuel tank area. I'm going to build a removable hatch so I don't have to tip it upside down to put the wings on it. Seemed like to much of a hassle.

I'm going to be running an OS FX 1.60 with a bison pitts muffler. I've been impressed with the plane so far, nice arf.

Basically have the hatch to build, install the pants, cowl and the remaining radio gear and it will be ready. I really like the throttle servo mounting up front in the engine box. Sweet setup.

Later,

Flyindoc

What hinges are you guys going to use? Are you going with the supplied Cya hinges, or an aftermarket hinge such as a pinned hinge or Robart Hinge Points?

Jon