RE: 4*120 Build Thread
 

I have considered longer gear for it. I may do that later on.

For right now, I've ordered a couple different sized 3-blade props for it. I've actually never used a 3-blade prop on a gasoline engine, so it'll be kinda neat to try it out on the Ryobi. I ordered a 16-8 and a 16-10.

TNT makes a different set of gear for the 4*120, but I'm not sure if it's much taller. I'd like to get a set thats about 2" taller than the stock gear, but all the other dimensions would be the same.

I'll check with them if I'm not happy with the 3-blade performance.

RE: 4*120 Build Thread
 

Hey, I'm new to the forum. Been building and crashing planes for 30+ years. Just got me a Mac weed- eater at Home Depot (same engine as the Ryobi 31CC short shaft) and got all the weed stuff tossed into the trash. Used a drill press to do most of the work hacking off the integral shroud around the magneto. Gott clean up all those neat little scallops. During all of this I managed to break the rings. I hate it when that happens. So, I gotta get some rings before I can even run the engine. Wacker engines looks to be the likely place to get the necessary modification parts, and I like the idea of a welded muffler assembly rather than what some of the other providers offer. I'm gonna start with the magneto for ignition, but that may change in time if starting proves to be an issue.

This is my first attempt at a conversion, so I've been doing a lot of reading on the subject. What do I put it in when the other stuff is done? After reading The thread, I think I'll settle of the four-star 120. The thing we have to worry about here is altitude. Where I live is 6800 feet, and our field is said to be at 7000. Things just ain't the same as they are at sea level.

Very insightful information so far. Projects look good. As for cutting curves and circles, might try an xacto knife in a cheap compass (where the pencil goes). Used it to cut a LE scallop design, and it worked great. A piece of glass under the mono seems to help, but is rather unforgiving on the knife blades. Looking forward to the test fright results.

RE: 4*120 Build Thread
 

RC: The fuse is complete with everything installed. The fuse only weighs in at 8.6 lbs so estimating the wing at 3 lbs, I should be in at 11.6 lbs or so! I'm not sure where the balance will be but have the battery and receiver that I can move around for balance, hopefully. I didn't put servos in the rear but did use a ball bearing elevator splitter. The elev and rudder servo's are under the canopy aft of the te. Gettin close now! Need to cover the wing and add in the servos and she won't be a hangar queen any longer!

TNT can custom make gear to your dimensions...a thought

Murphey (as in Murphey's Law)

RE: 4*120 Build Thread
 

I fired the engine today.

Took the plane over to a friends house and fueled it up. The engine is turning 5300RPM with a Top Flite 18-10 prop. Too much prop, (I knew it was too much prop) but I didn't have an 18-6 and I just HAD to fire it up and see how it runs.

Engine runs great and idles very smooth. With the elctronic ignition from C&H--it easily hand starts on the first flip after it runs for a couple minutes and warms up.

I did have a problem getting it to fire for the first time. It's a brand new engine, and a brand new fuel tank. I don't really have a way to choke the engine because the carb is only about 1/2" from the firewall. I can't get a finger in there to plug the intake for choking. Thank gawd, my friend has thin fingers, and he was able to get one down in there while I turned the prop over with ignition turned off.

Once we got fuel up to the carb, it was only a few flips to get it fired off that first time. Every time after that was 1 or 2 flips.

I'm expecting a couple different props in the mail. Hopefully they will arrive tomorrow. I odered some taller wheels, and that will allow me to use an 18" prop if I don't like the 16x8 3-blade props. I'll have 3" clearence under the prop when the tail is up and level--just as it would be during a take-off roll.

I forgot my smoke oil today, so the Sullivan smoke system didn't get tested. I'll wait untill I get a different prop on it and get the RPMs up closer to 7000RPM before I try the smoke pump.

I am hoping to get a video of the plane. A local friend has volunteered to do the video. Hopefully, I can put it on putfile.com

Only thing left to do is install the flying wires on the tail and balance it. I'll use kevlar for the flying wires because it's lightweight and the plane is slightly tail heavy right now. I really had no way to put the whole plane together and check the balance. I got it pretty darn close by using the "thats about right" method of determining where the servos and other components should go. I will admit, I am dissapointed that it's gonna take more weight in the nose to balance it. Maybe the bigger wheels that I ordered for it will help. And I think I am going to go ahead and get some custom gear from TNT. If I get 3/16" aluminum and make it 2" taller than the stock gear, that will add a significant amount of weight in front of the CG. I'd rather put beefier LG and bigger wheels on it than lead. At least the taller and stiffer gear is functional. After setting it up today and starting the engine, the stock gear is looking kinda floppy.

I don't know if you guys want to see more pics. Do you want me to assemble it and take pics sitting on the tarmac? Do you want full throttle smoke pics while sitting on the tarmac? I'll take the pics if you want to see them.

RE: 4*120 Build Thread
 

RC whats with all this tarmac crap, Is that a car you just built:D LOL. We want to see smoke in the AIR !! maybe inverted! a knife edge ! :D But maybe if your a little thumb shy we'll settle for tarmac




Ken

RE: 4*120 Build Thread
 

Heck yeah!!

We haven't followed you this far not to see the finished goods!

:D

BobbyG

RE: 4*120 Build Thread
 

I'll put the other props on and test the smoke system as soon as the props arrive in the mail. Should be Friday or Saturday.

I think I can twist my flyin' buddys' arm and get him to take a few snap shots while I'm flying. ;)

I REALLY want to get Retnavycdr to get the video camera out and video the maiden. If I can get the smoke system working right while I'm testing here at the house--we'll have smoke on the maiden!!

I may go ahead and fly it on the maiden without the flying wires. Not planning on doing anything to crazy on the maiden. Wellllllllllllllllllll, maybe a knide-edge pass or two with smoke turned on--but no snaps or tumbling maneuvers.[sm=lol.gif][sm=stupid.gif][sm=bananahead.gif]

RE: 4*120 Build Thread
 

Alright:eek: Alright:eek: Ya twisted my arm enough.

I'll take pics tomorrow with the plane assembled in the driveway. Might get my buddy over here to hold the tail down and we'll test the smoke system.:D

RE: 4*120 Build Thread
 

I have been flying my 4*120 for 3 years with no flying wires on the tail, I don't think their needed. The thickness of the stock gear lets it bend on a bad landing instead of riping out LG blocks. You will really like the 120 in the air as its big and does wounderful manovers that are so controbale with good power up front. With the huge wing there is no need to over power this bird like the 3D guys do.

RE: 4*120 Build Thread
 

This is my second 4*120. My last one had an OS120 Surpass on the nose. It was underpowered for my taste and altitude. I was flying in Denver at 6000' elevation at the time I had that plane. With a 120 4-stroke, it was anemic.

That was back in the day when I listened to the local "experts" and would only put the recommended engines on airplanes.

"Anything more than that, and you'll tear it apart!!":eek:

Those guys would poop their shorts if they saw my current project.[sm=lol.gif]

I loved the way it flew. That was the first plane that I ever did a flatspin with. It was so cool to see that great big plane doing a flatspin. But, I also discovered that it wasn't the best for doing level knife-edge passes down the runway. It always lost altitude. Thats why this new one has a bigger rudder. Slow landings were easy.

RE: 4*120 Build Thread
 

I got smoke pics!!

Retnavycdr came over today and we set up in the driveway. Roger turned on the video and we got some nice footage of the engine running and the smoke pumping.

I'm having problems getting the programming correct in my TX. I'm using a JR8103 and I have the smoke on my flap channel. I've disabled the flap pot, and programmed in a 5-point curve. But, I'm not getting it right.

Right now, all I have it ON and OFF. The pump is putting out WAAAAY too much oil, and it's not smoking as good as it should. If I can get the programming figured out and slow down the pump, it should smoke like gangbusters. It's just dumping smoke into the muffler now--and it's pooring out all over the ground.

If the wind ain't blowing tomorrow--we're gonna test fly this baby. I'll try and twist Rogers arm again and get him to video the maiden. It's not hard to get Roger out with the camera. He loves this stuff.:D

Roger has a video of the smoke and engine running in the driveway, and he's working on putting it on a disk right now. I'll post it on putfile.com when I get it back from him.

I put a Master Airscrew 16-8 3-blade prop on the engine and I now have about 6000--6100RPM out of the Ryobi. Not what I was hoping for, but it will hopefully gain some RPM as it breaks in. I may switch to a 17-6 or 17-8 2-blade if the RPM don't come up closer to 7000RPM after a couple gallons.

Pics:

RE: 4*120 Build Thread
 

almost !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!:D

RE: 4*120 Build Thread
 

RC just a thought here, are you still running at a high elevation ? Could you not lean your motor out a bit more giving you a higher exhaust temp. which would burn up the oil faster.



Ken

Murphey, Love that colour scheme, looks awesome.

RE: 4*120 Build Thread
 

Maiden flight today.:D 2 flights. Brought it home in one piece.

Cut my finger on the prop while starting. Got the pics to prove it.

I'm still wanting more RPM from the motor. Right now only getting 6000 with a MA 3-blade 16x8. I'm going to cut down to a 17x6 2-blade and try that. Plane flies very slow and is a floater.

It took 2 clicks of down elevator to make it fly level. I didn't need any other trim adjustments to make it fly hands-off. YUP!! She's straight.

I'm still fooling with the smoke system. Just can't get it adjusted properly. It's just a matter of finding the right amount of end point travel in the radio. I'll figure it out eventually.

Pics:

RE: 4*120 Build Thread
 

awesome man, just awesome!

heck of a job

;)

RE: 4*120 Build Thread
 

Guys, here is my finished product! She's still a Hanger Queen...haven't had a chance to maiden her yet...maybe Saturday. Here are a few mods I made (some taken from RC and C Heath):

Tail surfaces rounded and counter balanced tips; fuse between F-1 and F-2 shortened 1"; hatch on bottom behind F-1 for ignition access; hatch on bottom of fuse aft of wing TE for access to rudder and elevator servo's; cocpit moved back and canopy trimed down a lot, carbon fiber pushrods throughout . I uese an Evolution 26cc gasser with tuned pipe, Bambola 16X8 prop, Hitec HD BB servo's JR 770PCM receiver and and 5 cell NmHi 1400MAH receiver battery. Dry she weighs in at 12.3 pounds. The CG is right at the aft limit.
I thought the kit went together very well, the wood was fair and instructions clear. I didn't like the open structure of the wing with no LE sheating and capstrips. I have no doubt it will fly well...anything that Bruce Tharpe was involved with does!

Pictures of the first flight to follow

Murphey...(As in Murphey's Law)

RE: 4*120 Build Thread
 

killer!!!!!

RE: 4*120 Build Thread
 

I love the covering scheme. Much more interesting then my canary yellow.

I gotta dress mine up a bit.[8D]

Nice job Murphy. Bring her down to Pueblo and we'll put them up together.[sm=thumbup.gif]

RE: 4*120 Build Thread
 

I'll fly it this weekend and post a few pictures. I'd like to get together for a little 4*120 around the pea patck. Thanks RC!



Murphey (As in Murphey's Law)

RE: 4*120 Build Thread
 

I go to Denver sometimes to vist the in-laws. I could stop by your club and fly there if you can't make it down to Pueblo.

My wife is talking like she may go to Denver on the weekend of Feb. 17th--18th and 19th. I could maybe make the trip with her and fly for a day.[sm=thumbup.gif]

RE: 4*120 Build Thread
 

I braved the cold and crosswind and flew her on Sunday. I must say it was a "non event". Just took off and flew like it had several flights in the logbook! It sure floats in for a landing...overshot twice! I like the handeling charistics. No roll coupling with the rudder, and inverrted just a touch of down! Loops, split S and the usual easy stuff is very smooth. On the Evolution 26cc, I put a APC 17X6 and she reved up to 8600 static. Needless to say plenty of vertical! and no increase in airspeed on the downline!

I really enjpoyed this building thread...kept me motivated and gave me some great ideas!

RC, be sure to give me a call when you come up to Denver this month. Go to crosswindsrc.com for a map to our field.

Murphey (As in Murphey's Law)

RE: 4*120 Build Thread
 

Congratualtions! It's a beautiful airplane. [sm=thumbup.gif]

RE: 4*120 Build Thread
 

Hi everyone, great thread and a lot of nice planes here. I just purchase one of the planes at a local auction without an engine. I was leaning towards the one from www.scottellingson.com. Looks like this will be a nice flyer. The sevos that came with it are futaba 3003's and I don't think they will hold up. What servos compatible with futaba should I use? Thanks, Grayle

RE: 4*120 Build Thread
 

C HEATH: Do you have any pics with your toro 25 cc installed? Did you put any right thrust into your firewall? I trying to decide between the Ryobi and Toro. Ryobi: move fire wall back 1.5-2.0 inches and keep the cheeks, or Toro cut cheeks and leave firewall alone. Decisions Descisions:D

RE: 4*120 Build Thread
 

Hi Guys - Some great looking 120's being built. I thought I might share a few things I did different. Some of you were wondering about flying wires. I have not used them on mine either, and it does fine. What I do different though is to add a little tri-stock balsa under the horizontal stab on either side of the fuselage. I also come down through the top then with 3 holes, and then insert dowels that will fit down into the matching holes in the fuselage. I then put some bigger tri-stock on the top of the horz stab on either side of exactly where the vert fin is going to fit. I sand and mold this in so it looks like it was suppose to be there in the first place. Once that's all done it almost stays in place without epoxy :D. See pics below for details. I also like having a fuel tank hatch that I can remove, also see pics below. Since I did a pretty extensive bash on this 120 to try and re-create a semi-scale version of AirTractors 802F Single Engine Air Tanker, a lot of the rest of the plane looks a little different. The horz and vert fins I built from scratch as well as theflaps and ailerons One of my biggestchallanges was in trying to build the cockpit. This was only my 2nd kit build, so I learned a lot about shaping styrofoam, etc. ;) What makes this an Air Tanker (Slurry Bomber) was the addition of the sluury bays on the bottom of the plane. Each bay holds right at one cup of slurry (flourer or baby powder), and both bays open at once. Makes for a pretty cool slurry drop with the flaps extended and low and slow :):D:). It flies very scale with the Saito 150 and Graupner 15 x 8 pulling it around. Is a little hard to land sometimes due to it wanting to float and float --- and float[X(]

If anyone is interested, I have a bunch of build pictures of this whole project on my website at [link=http://groups.msn.com/PuttsRCHomePage/]Putts RC Home Page[/link]. I think there around 160 pictures of it in a album called "Sig Four Star 120 Build".