merto31

Can you guys help me to make a pull pull system what do I need and any ideas or illustrations on how to do it.

acdii

Easiest way is to just go buy one. The fittings for it are not that easy to make, and the kit comes with everything you need.

merto31

yeah but which kit exactly size and all?

flygilmore

I'd go with an HD one.......

Honestly though, since this is a "sport plane", the rec. setup will work just fine. This is not a super high performance 3D plane and if you flew 2 of them back to back with both setups, I don't think you'd know which was which. If you are experienced in pull-pull setups then by all means go for it. I'm guessing since you're asking these questions however, that you have very little experience with them and would save yourself some headache by going the stock route. Geometry on pull-pull has to be set correct or you'll get slack lines when the rudder is moved which can lead to big probs.

FWIW, I'm building this bird and will be using the stock setup with servos mid-fuse. I myself haven't run a setup like that in many years but I'm going to give it a go.

merto31

I wanted to use the pull pull so I can learn how to use them and learn all the bad and good things as I am gradually heading towards a bigger 30cc 3d airplane

FlyerInOKC

My Feedback: (6)

I would suggest the following:

Dubro Heavy Duty Dual Pull-Pull System with 4-40 rods and clevises, its rated for a .91 and larger aircraft.
Great Panes Deluxe 4-40 Pull-Pull system
Sullivan Productions Kevlar Cable system (This is nice if you don't want/like steel and its rated for100 lbs. of pull.)

They are all good products and about the same price range.

Mike

merto31

thanks FlyersInOKC

tailskid

My Feedback: (34)

Do you guys realize this thread is 10 years old and still going strong? Proof of a good design and committed builders!

acdii

Yep. almost lost mine at the SIG Fly In. Dead stick way out, but thanks to its floating forever I was able to guide it back towards the strip using glider technique of trading altitude for speed, and just touched the weeds coming in. Turned out dummy me forgot to fill the fuel tank! DOH!

Gray Beard

My Feedback: (-1)

Yep, been around for a while and pops up quite a lot. The 4* is still a great design and kit. Lot of copies of the design too. A lot of ARF rip offs.

FlyerInOKC

My Feedback: (6)

SIG designs are the Energizer Bunnies of R/C!

lamarkeiko

My Feedback: (1)

I hope there is still some life left in this thread, because I'm finally back to building my 4 Star 120 and I have questions.
I stopped my build a couple years ago mostly because I needed an engine to continue on, and then I got side tracked building a BTE Venture and a few ARF's. The engine I ended up getting is a Valley View 20 cc gas.
I have my tailfeathers built and the left & right wing panels are done except not put together yet, which leads to my first question. I've read through this whole thread and I don't remember anyone mentioning reducing the main wing span. After flying my BTE Venture, which I think is just about a scaled down version of the 120, (both designed by Bruce Tharp) I feel that I may like the performance gained with shorter wings. I have already rounded my wing tips at the end rib section, which has reduced my WS to 80" from 81". I was thinking of taking off one rib panel from each side which would give me a total WS of 72". I'd appreciate any input on this subject. I have more questions to follow.
Thanks
Lamar

lamarkeiko

My Feedback: (1)

I forgot to include some pictures of my build so far.

Flyboywbl

Your wing loading will go up if you remove one bay from each wing. When I built this plane with a heavy 31cc weed eater engine I opted to keep the stock wing. I also mounted the aileron and rudder servos in the tail to counter act all the extra weight in the nose. I was advised not to clip the wing because the engine I chose was very heavy and under powered.

if your engine is light and powerful you should be ok to clip the wing. If you clip one wing bay it will be a snappier plane but it will have a higher stall speed and aproach speed. If you are comfortable with that, than go ahead.

personaly I love this plane more with a clipped wing. I have had both the 40 kit and arf and now I have the 54 arf which is clipped and it is a great sport plane. It does not do 3D but it will do all the basics with no bad habits. I have a Magnum .52 four stroke with a 12x6 prop running 15% nitro.

brockettman

Hi Lamar, from the looks of your pics, you have a real nice build going there! I reduced the wing span on mine to 78" and she's still not real snappy in rolls, and still floats like a trainer! It's a pretty big bird though, and probably not meant to be too nimble...

I have been considering taking out one more section at the end of the wing... You can see what I did with the tips in post 701. If I do modify the span I will cut down the amount of balsa in the tips a bit too. 72"-74" might be the sweet spot...

I have 6 flights on mine so far, and have replaced the original aluminum landing gear with a stiffer set. Still trying to dial in the prop size for best performance as well...

Build well!

Ben

lamarkeiko

My Feedback: (1)

Thanks Ben and Flyboy for your input. I was really leaning toward clipping one rib bay, so that's what I'll do before I put the wing halves together. I would like to be able to get a faster roll. My BTE Venture seems like slow motion when I do a roll. The 20cc Valley View engine I have weighs 32 oz with muffler and electronics. I don't think that is very heavy compared to some engines used in this thread. As I read through this thread, it lookes like most people ended up with a tail heavy plane, so I think I will do all I can to keep the weight more forward. It will take a lot less weight to balance a nose heavy plane than a tail heavy one.
You may have noticed from my tail feather build that I did some bashing there. Besides rounding them I also added 1" to fin and rudder height, 1" wider rudder and elevator. I also framed them up with 3/8" stock instead of 1/4" and I"m not putting the 1/16" sheeting on top. I'll be covering with Koverall. Don't know how that will affect the tail weight, but I'm hopping it will lighten it up some.

Lamar

FlyerInOKC

My Feedback: (6)

Good luck Lamar! I have been waiting for you to start up again. I too have suffered from stalled builds in the past.

Mike

lamarkeiko

My Feedback: (1)

Last night I proceeded to remove one rib bay from one wing half. I was a little hesitant at first, but it was really very easy. I did some calculations to see how many square inches of wing area I will have on completion.
With the rounded wing tip, which also includes the aileron being tapered at the end, I am reducing my wing area by 169 sq in. The Four Star 120 is listed at 1205 sq in, so that will leave me with a total of 1036 sq in and a reduction of 14% in total wing area. Of course I did add 1" to my elevator width, which I think may be included in total wing area which I didn't figure in.
With my total wing span at 72" now, and plane length at 66" which includes the 1" extra rudder & elevator, will the straight line tracking improve?

Lamar

kmeyers

Wing taper, wing length, larger ailerons, more deflection and lower total mass for roll rate improvement.
Fuselage profile square surface increase for tracking improvement.
You have some of these going for you. Not much really, but, your new higher flying speed may change the presentation to appear so.
MHO
How much change over stock are you looking for?

acdii

I removed a bay on each wing, and made rounded wingtip blocks, which added a total of 3" to the shortened wing. The blocks are fully rounded, not flat on the top and bottom like on a trainer, but like on a full scale plane. The plane floats forever. I would not worry at all about wing loading, this plane has more than enough, especially with a DLE20 clone. Mine is getting the DLE20 replaced with a DLE30, as soon as I get the correct standoffs for it. That can help reduce some dead weight in the nose, maybe even all of it, and that extra 10CC of power should have this plane moving! Although, I have to admit, with the DLE20, it moved so fast the covering started peeling off the stab.

If you are looking for fast roll rate, you have the wrong plane. The dihedral and large wing and tail slow it down a bit when rolling, but it does great knife edge, inverted, and amazing snap rolls for something so big and heavy, and because its so long, it tracks as if on rails. With a larger elevator, be careful when pulling up, you may overload the wings, the stock elevator can pull this plane up pretty fast, and larger ones will increase the G-forces even more. The larger rudder will be fun though, I can see that being much more helpful with doing crazy aerobatics. Dial in plenty of expo for taking off though, or it will be all over the place, it needs very little rudder when the tail comes up, and the larger rudder could be a hindrance taking off.

One more tip, add a little more right thrust with a couple washers on the left motor mount, trust me on this, I have had 2 4*120, both needed it, one was an ARF, the other I kit built, both with the DLE20. The ARF suffered from wing separation of Extreme Prejudice effect(see note about pulling up above), and broke apart during a barrel roll. The kit built one I started from plans, and it too needed added right thrust, it made a huge difference in taking off.

lamarkeiko

My Feedback: (1)

Other than what I've already done, I don't have any other plans in bashing this plane. I may make the canopy a little smaller and try to stiffen up the LG, which seems to have been a problem. I may also make a hatch for access to the fuel tank & electrics.
I know I'll never achieve a fast roll rate with this plane, but I would like it to be a little faster and not float as much.
Thanks Acdii for the info on the elevator. Maybe I didn't need to increase its width, but now it's done, so I'll be keeping a close eye on how it pulls up when I first fly. With the DLE 20 installed in you 4 Star, I assume you needed more nose weight to balance. How much weight did you add, and where did you end up placing your servos, batteries and electrical? I don't want to add any dead weight if I can help it.

Lamar

acdii

On mine, the tank is on the CG, the ignition, and both battery packs are in the nose, and the throttle and rudder servos in in the stock locations. I added a choke servo to where the elevator servo goes, and moved that one to the tail, which added some tail weight that I had to compensate for. I made a belly hatch right behind the firewall that I can remove to access the packs and put the weight on that. I have had that hatch fall off in flight making it tail heavy , and was probably the easiest landing I made with it. It was balanced with the goldberg plane dumper, which I no longer trust to properly balance a plane, so when I swap the 20 for the 30 I will hang it with the Vanessa Rig and balance it with that. I would not be surprised to find it is too nose heavy at the moment, which is probably why it tends to slam into the ground when it lands and not kiss it smoothly like all the other planes do that I balanced with the VR. With so many hard landings the gear is permanently splayed and will need to be replaced. Once the tension in the aluminum is gone, there is no getting it back without heat treating it.

lamarkeiko

My Feedback: (1)

Thanks acdii for the info on you 120. I'll be just putting my servos in the standard location per plans, or as far forward as I can get. Won't be using a choke servo.
Are the pushrods that are supplied with the kit acceptable to use, or would there be a better option?

I had a little set back last night while in the process of epoxying the wings together. I epoxied the dihedral brace on one wing half, and sat back watching the Warriors basketball game while the epoxy set up. At half time I went back to finish epoxying the wings together. When I slid the other wing half on to the dihedral brace, I then instantly realized that I had epoxied the brace upside down in the wing half. I spent the next hour trying to get the brace out of the wing. 15 minute epoxy can set up real good in 30 minutes. Fortunatly it wasn't rock hard, and I could cut the epoxy out with a chisel. I squirted alcohol on the epoxied area to soften it. Then after lots of pulling I got it out and no damage was done.

brockettman

I put all servos in the standard location too, and also used the pushrods that came with the kit, the configuration seems to work fine. One thing I did upgrade are the control horns and I also reinforced the aft fuselage with carbon fiber tape and epoxy to stiffen her up between the wing and tail feathers.

Lamar, sorry to hear about the setback with the dihedral brace... Glad you got it apart without any damage!

Super08

My Feedback: (2)

Something else that works is to hit it with a heat gun. The high heat will liquefy unset epoxy.