ec121

My Feedback: (2)

Thanks. I will try a 17x6 later. I already had a 16x8 in my stack of props. The engine seems to really wind up rapidly with the 16x8. I was going to use something to load it up a little more after I got it checked out. I believe the 26 would pull a 17x8 without much effort, but it doesn't need anymore top end. I had a 20in prop on it for a trial while I was running it on my test stand. It pulled it but under protest.

CAT POwer

My Feedback: (61)

James are on 72mhz or 2.4 ?

lrglnman

Still running 72. Just cant seem to make the big plunge into 2.4 cause my 72 radio is just a few years old. Just gotta be careful about any metal to metal contact and run a pcm receiver.

lrglnman

Just an update. got to fool around with the plane this evening . heating up the wrinkles. I read a post back a few pages that said the stars and stripes were vinyl and that turned out true. I fooled around with the iron and heat gun trying to work the wrinkles out and found out the iron just dont cut it. Use the heat gun and work very slowly, repeat very slowly, and keep a good distance away from the covering. Just warm the covering till you see the wrinkle start to shrink then back off . keep doing this will remove the wrinkles , even under the vinyl stripes. after the covering is nice and tight i used the iron and hit every rib and area where there was no vinyl covering. I also held the wings and tail feathers in my hand and worked the heat gun with my other hand . doing it this way i could hold it in such a way the light showed my progress. No doubt a few of you will yell at me for using a heat gun to pull the wrinkles out but if you use the iron you risk ruining the stars and stripes. My method yealded a super nice finish . I also let the plane set a few days before i ran the heat gun and iron over it so the wood in the plane would acclamate to the very harsh Tennessee climate. Seeing how these arf's come from a more milder area where the moisture lvl is alot higher and then shipped to a less humid climate , its no wonder they have wrinkles. Oh and Ill have to get the wife to fix the camera cause i know nothing about it. so hopefully ill get pics up soon.

eclipse3g

My Feedback: (5)

To whom who has already flown 120 Decathlon.
*****
I try to find out an exact location of the CG of the plane.
The manual says - "The center of gravity is locate 10cm (100mm) back from the leading edge of the wing". Mike Buzzeo from his review is saying that the CG is 70 - 90mm from the leading edge of the wing.
http://www.rcuniverse.com/magazine/a...rticle_id=1152
Even that 70-90mm has a huge gap and Mike should have known that! It should be 70-80 or 80-90 or something like that, but not 70-90mm.
In my past experience with Phoenix .46 Decathlon manual was wrong. That Decathlon needed the CG 20mm to the front from what manual was saying. In money wise perspective, I totally understand Seagull and Phoenix Vietnamese companies - more crashes more money from selling spare parts. It said that the Chinese companies do the same – making planes more tail heavy.

I do not like to experiment with this plane as I did with Phoenix one. Where is a CG of the 120 Decathlon guys?

Lifer

My Feedback: (1)

eclipse3g,

If it is a standard wing with no taper or sweep, you can ALWAYS balance at a point representing 25% of the chord, measured back from the leading edge. This is a safe place to start. Moderate throws on the elevator, and pre-set your rate switch to 60% of the high-rates. Roll and yaw axis are not particularly influenced by c/g like the pitch axis always is.

Enjoy the plane!

eclipse3g

My Feedback: (5)

Thx Lifer

Lifer

My Feedback: (1)

My pleasure!

eclipse3g

My Feedback: (5)

Came home and checked the width of the wing. The width = 333mm. 25% of that is 83mm. Mike and Lifer were right, but not the manual. CG = 83mm. Seagull as Phoenix want you and me to buy extra wings

SJNason

I bought one to put my G20 in, hope to finish and fly it this weekend.

I followed MinnFliers review of the plane, great info, it was a lot to do with my choosing to go with this model.
I couldn't figure out what all the servo extentions MinnFlier listed were for. The are as follows
Aileron Servo Extensions: Four 6" (152mm), One 12" (305mm) Three dual servo connectors
Elevator and Rudder Servo Extensions: Three 24" (609mm)

All I could see the need for were for the Ailerons.
I plan on putting 2 @ 18" in the wings 1 for each aileron servo (looks like 12" would be just a tad short)
and then 2 @ 6" in to the reciver for the Ailerons 1 for each channel to make it easier to hook them up.
all the other servos are in the cabin so I couldn't see a need for anything there, am I missing something?

I haven't made a final desision on batteries yet. I think it will be lithiumIon with a voltage regulator for ignition and A123 for reciever

I am planing to put skis on it for the winter to fly off a local pond. Anyone else using skis with this bird? I plan to make my own and am looking for imput on how big they need to be. I have a pair I started a couple of years ago for a Dragon Lady 90 that I think will work not sure of the exact size but I think they are 4" X 12". It would be great to get some imput from people who have already had some experince flying this plane with skis. Thanks in advance.

SJNason

Thanks, you have convinced me to fork out the cash pick up a heat gun.
I have been trying to get away with out one for years but getting the wrinkles out with an iron is a pain in the *****


I now that I have used it, I would never go back to using the Iron fpr this.

eclipse3g

My Feedback: (5)

Basically I finished the plane. Trimming lines, stars, beams were pain in the a…s.
The last picture is a Photoshop test picture (in the process) before ordering vinyl stickers from Kirby.
I tried struts today. They are too heavy - almost 190g or 6.7Oz. Probably I will make new one from balsa. Has anyone rebuilt the struts?

SkyPilot101

Nice finish eclipse, yea, those struts are heavy!

eclipse3g

My Feedback: (5)

Thx, SkyPilot101,
I think 190g or 6.7Oz are not a big deal for this plane (basically nothing), but I have time to re- built the struts because I don't fly in winter.

Kostas1

How easy would it be to remove all the covering

and make a custom one ?

ec121

My Feedback: (2)

I have used the struts on mine. It is so light that you won't notice the weight. I used 80mm for the CG. Lands fine. Doesn't balloon when the throttle is cut on final. The struts look too big. I am tempted to round the corners off and paint them. That would be easier than making new ones. Also could buy some airfoiled aluminum strut material and make some. The only PTA would be fitting the jury struts in the middle. My only real complaint is the rattling of the clevises while it is flying. Sort of a buzzing rattle. The holes are too big in the mounts. I may need to adjust them a little tighter to put some tension on the connections.

eclipse3g

My Feedback: (5)

Thx ec121 for your input. I feel that those struts are OK for this plane. It's not a 2Lb foamy one .
Just nothing to do during winter time and I want to make new struts.
I also set a CG around 85mm. Maybe your rattling sound is coming from pushrods? They may vibrate in tubes.

>>
Kostas1
If you familiar with covering films (Monocote or Ultracote on whatever you used) the covering work is not difficult, but on the initial stage when the ailerons, elevator, rudder and fin are not connected to the fuselage, wings and so on. If the plane is assembled, the covering work is challenging. Some people cover the plane splitting surfaces by small areas. However, seams of one color are visible, and the plane looks like after a repairing work.
Also this particular aircraft has a weak point - side windows. They are permanently glued into the fuselage. You cannot easily remove them during covering work (I unsuccessfully tried)

SkyPilot101

Other mods.
The push rods are carbon fiber 2.5mm rods. J-B weld was used to attach the clevises to the rods.

eclipse, what size rod ends fit the 2.5mm c/f rod? where did you find c/f rod in that size, I'd like to duplicate your method & toss the weak stock pushrods.

What size prop do you have in your pic's, think the GP Extra LG is tall enough for a 17 in. prop?

eclipse3g

My Feedback: (5)

1 - Carbon push rod. Diameter = 2.5mm. 4/40 pushrod around 2.8mm
http://cgi.ebay.com/RC-R-c-Airplane-...item3ca2ef1128
2 - Aluminum tube from my local Hobby store
3 – Sullivan 2-56 x 1" Threaded Steel Studs (all thread)
4- 4/40 metal clevis glued by JB weld to the pushrod. There is not enough space to use aluminum tube which could’ve been a better solution. The slot for the rudder push rod is too close to the control horn. I did not like to make the slot bigger that it is.

The prop is 15X8 Xoar. It was painted manually. I know that 16X6 or even 17X… will be better, but for initial flights I don’t want to put a bigger prop. Bellanca has a short fuselage and I’m afraid of ground loops which I had on my Cub J3. Later on I will put a bigger prop if the plane needs it.

aramsdell

I'm in the middle of building the 1.20 size. Has anyone flown without the HUGE through-bolts used to go through the wing and joiner tube? Are the wings likely to fly off? The Nylon wing bolts for inside the fuse were extremely loose fit in the treaded portion in the wing> I coated the nylon bolts with heavy grease and put epoxy in the threaded holes and let it set them unscrewed the bolts when it set up. I see a picture here using different control horns on the tail. Mine has 3mm bolts and aluminum washers all around. The tailwheel on mine is REally cheezy. a piece of 2mm allthread with some nylon tubing over it to space the tiny wheel to the center. The arm attached to the bottom of the rudder is huge/heavy. Actually all the hardware seems HEAVY..
Mine may initially be underpowered for all but scale flight, we'll see. I have an RCGF 15CC that needs a home and cowls are available. This may go to the NEAT Fair next september.(electric) That would mean new cowl.

SkyPilot101

eclipse, Thankyou very much for the detail on your pushrods, I actually never thought about using tubing to join the c/f to the allthread!

As far as the wing bolts through the joiner tube, I did'nt use them and have had no problems so far.

eclipse3g

My Feedback: (5)

You are welcome SkyPilot101

I also have never heard about nylon bolts problem on Seagull models. As far as I know that solution Seagull implements on all their aircraft. I had a Phoenix Decathlon, Vietnamese plane as well, and the same wing bolts were their.
I did not use stock hardware. I have a lot of that stuff from other planes.
My tail wheel is bigger and softer than the stock one (probably from DuBro) and you, aramsdell , can always replace yours as well.

I wanted to implement this kind of pushrods,
http://www.centralhobbies.com/contro...e/pushrod.html
but the stock push rod tubes are too small in diameter to handle the carbon tubes.

aramsdell

I actually will use the tailwheel. It is not foam like on the 72" Yak I got last year. No flat spots. I will change the tiny allthread to a 2mm shoulder bolt and use some brass bushings. The bushing through the spring aluminum arm is loose and needs fiddling as well.

SJNason

I decided not to put the bolts thru the wing tube. I flew it for the first time this afternoon off a frozen lake. I took it easy and never really put it thru the wringer acrobatically but so far no issues... I have never seen them required on other aircraft and never had issues before however I may pick up some steel bolts to replace the nylon 1/4-20 thumb screws that come with.

I used all the come with hardware except for 2 of the clevises on my elevator, I broke one during installation and had to replace it with something else and of course I had to make both elevator halves match. also replaced the tail wheel as it is the same as the one that came on a Seagull yak I had and it only took a couple of flights to wear out the plastic hub. I put one one I had from a Sullivan tail wheel set that has an aluminum hub.

The manual called for using 3x10mm machine screws to mount the cowling but I couldn't find any blind nuts in the fuselage for them I ended up using a dubro cowl mount kit instead.

I centered the G20 bolt partern on the hole in the firewall and used a set of 1 1/2 aluminum standoff everything lined up nice with the cowling

The G20 seamed like plenty of power for the plane. I used 83 cm for the C of G and it felt pretty good there.

Can't wait to get it in the air again. maybe this weekend if the weather is good.

eclipse3g

My Feedback: (5)

Thanks for your flying report, SJNason.
Actually it's not clear for me - "I decided not to put the bolts thru the wing tube".
I lost the manual and don’t see on the wing/fuselage where to put those bolts in. I have 2 bolts to secure wings to the fuselage (inside a cockpit), but nothing to secure the wing tubes. On all my Seagull planes, Ultimate & this one, they are (tubes) from kind off paper and glued in the wing permanently.
Now I see almost everyone moved a CG location forward. Did you notice some squirreling during takeoff?
Good point about a tail wheel. I use a 2-56 bolt as an axel for that. You are right - the tread will destroy a wheel hub easily.