RE: 4*120 Build Thread
 

Hi Guys,

I've got a 4* 120 in progress and thought I'd post a few pics of my kit bashing. I dropped one bay from each wing and added a balsa tip, enclosed the nose, re designed the canopy (I still may use the stock one), and did a little modification to the wing tips elevator and rudder.

Build well,

Ben

RE: 4*120 Build Thread
 

Looks sharp. Keep us informed.

RE: 4*120 Build Thread
 

Yes looks good indeed. Are those wing tips solid balsa? How far did you go on the Rudder?

RE: 4*120 Build Thread
 

Thanks guys,

Yes, the wing tips are solid balsa, a little bit more weight but I think it makes the wing a little sturdier waaayyy out there at the end:D Plus, I can shape them the way I want...

I extended the rudder by about 1/2" on the trailing edge, and added a little "swoop" to the top...

Another thing I did was to modify the aileron servo mount so the connecting rod doesn't have to be bent.

Build Well!

Ben

RE: 4*120 Build Thread
 

Very good ...
I am going to keep the bend out of my push rods as well.
My Kit should be here today!!

RE: 4*120 Build Thread
 

I just started my 4*120 build last night. I plan on doing something similar to what your doing. I'm going for sort of a cross between a 4star and a super chipmunk :) I'm going with the Crrcpro Gp26R engine (just had one handy) and one of the things I was thinking about doing was raising the forward portion of the fuselage a bit and bringing the bottom down a bit then making a cowl for the front that looks similar to that on the chipmunk.

Something I'm kinda stuck on though is that I'd like to raise the engine a bit (head mounted down) so I can get more of it in the cowl. However, I'm really not sure what that might do to the flight characteristics. I'm sure I'll have to (at a minimum) adjust the CG but does anyone else know what else I'm getting myself into if I were to do this. I'm thinking maybe an inch above the center line on the plans.

Thanks,
Russ

RE: 4*120 Build Thread
 

To raise the engine will be like adding some down thrust to the engine. I doubt you will notice it.

RE: 4*120 Build Thread
 

Thanks w8ye, I suppose if I did see too much down thrust I could always decrease that by slightly changing the actual thrust angle.

Thanks,
Russ

RE: 4*120 Build Thread
 

See how the plane flies first for you may not notice any difference.

RE: 4*120 Build Thread
 

<span style="font-size: larger; "><span style="font-family: 'Comic Sans MS'; ">I've been really considering this plane for my next build. I've done the 4 Star 60. Will a DLE-20 be ok for this plane? I want to move into gas next, but don't want to start too big.
Lamar</span></span>

RE: 4*120 Build Thread
 

The DLE 20 will fly it just fine. I've seen them fly with 91 two strokes. The DLE 20 has power about like a Saito 150.

Most 4*120's nowdays have 30cc engines but one would fly great with a DLE 20.

RE: 4*120 Build Thread
 

<span style="font-size: larger; "><span style="font-family: 'Comic Sans MS'; ">Thanks w8ye. I happen to have an OS GT-33. Is that engine too much for the 4 Star 120?

Lamar</span></span>

RE: 4*120 Build Thread
 

The GT 33 is not too much and will be a lot more exciting. But the plane will fly fine with the DLE 20

RE: 4*120 Build Thread
 

I am also wanting to build a Four Star 120 and I am on the fence about what size engine to use. Initially I was set on a DLE-20 but now all this talk of bigger engines has me re-thinking my choice. Does anybody have a video of the Four Star 120 flying with a DLE-20? I have searched high and low and I cannot seem to find one. I am not a 3-D guy but I do like good vertical line performance. I generally build pretty light and don't plan on any heavy modifications. I have also been thinking of using a RCGF 26cc if that would be better. Does anybody know if the RCGF 26cc would be a better choice or would they about the same? By reading through several threads I have received all kinds of reports from being able to hover the 4 Star 120 using a BME .90 (converted to gas) to marginal verticle performance with a Zenoah G-38 (really??). The DLE-30 seems like it would be overkill to me...

RE: 4*120 Build Thread
 

Four Star 120's flew very well for many years with 120 four strokes and everyone was happy. The DLE 20 is a 122 gas two stroke that puts out the same power as a Saito 150.

The DLE 20 and 30 have been more successful with more sales and support than the RCG/RCGF line of engines.

The DLE 20 weighs less than the DLE 30.

RE: 4*120 Build Thread
 

A few years ago, I put an XYZ 50 cc engine in my 4 * 120 (see post #333). I know these are not the most powerful engine , but vertical seemed to be unlimited. FUN to flyjb

RE: 4*120 Build Thread
 

w8ye, I appreciate the comments...I am going to stick with my original plan and get the DLE-20...I just needed a little reassurance....

RE: 4*120 Build Thread
 

I've enjoyed going through this thread. I intend to replace my old "beater" 4 Star 60 with a new 120 soon. I'd like to bring up the topic of building the wing as a 2 piece version, as was mentioned about 3 years back. I was wondering if it were possible to replace the wood ply joiner with an aluminum joiner (crutch?) as I believe was done on the ARF version. Any thoughts on this? That's a long wing when not clipped. My intention is to use a DLE 20cc. My personal feelings on 4 Stars are that they are what they are[8D] . I love to drop back to a relaxing 4 Star after flying my other "hotter" models. I want the 4 Star to be a floater, and don't look for unlimited performance.
Pete

RE: 4*120 Build Thread
 

awesome. This thread is 7 years old. Still going strong!

RE: 4*120 Build Thread
 

I have a dle 30 on mine. I havent flown it as of yet bit it balanced perfect. Better a bit more poer than not enough. Theottle control.

RE: 4*120 Build Thread
 

<span style="font-size: larger; "><span style="font-family: 'Comic Sans MS'; ">I've got my 4 Star 120, and I'm ready to start my build. I'm going to order a DLE-20 from Tower to power it. I would appreciate some advice on other items I will need to run this engine so I can get them ordered at the same time. What would be the recommended prop size for break in and flying. What size battery for ignition is recommended. What size fuel line do I need. Looking at the measurements for mounting this engine, it seems that it will fit ok, but the cowl may have to be cut to accomadate the muffler. I want to mount the engine inverted. Can someone give me any advice on this. Any advice on these questions would be appreciated plus anything I may have left out for the engine.

Thanks
Lamar<br type="_moz" /></span></span>

RE: 4*120 Build Thread
 

Go to badbradgraphics, and get what you need there for the DLE. Get the Optokill switch, the mini tach, 1/8" fuel line, and the fuel dot too.  They also have the CM6 spark plug, dont use the stock dle one.  He usually has batteries too, but I dont see them on his page. I get stuff from him when O go to swap meets as he usually goes to them around here.  I used the charge jack/lighted switch for the ignition, the Ubec regulator, and the Optokill for my DLE20.

The battery you want to use is a 4 cell Nimh of 2000 mah or better. Dont use a 5 cell unless you have a voltage regulator too, the ignition may say it can run on 6 volts, but others have had the ignition go bad on the higher voltage. I run mine on a 4 cell and the charge lasts a long time.


I joined the 4*120 club tonight, picked up the ARF version in red from my LHS, they had it hidden on a top shelf.  Got it for $275, and knowing how hard these are to get, jumped on it.

I have the same question as Lamar does about the engine mounting, can it be upside down with the DLE20?    Did you guys do anything special for the switches and fueling for the gas engines?

RE: 4*120 Build Thread
 

Just found this thread. Have had a 4/120 for many years. I'm thinking I got it in 1990. I used to use it for a testbed for my larger motors. I think, among others , it has flown with a ST90, OS 120fs, Maloney 125, Zenoah G23, and ST 3000. Great flying airplane. It really moves with the 3000, would like to get it converted to gas someday.:D

RE: 4*120 Build Thread
 

I goofed up today mounting the switches. Dumb@$$ me put one right in line with the throttle servo.  Didn't notice until I get them all in and flipped it over.   OTOH it didnt look like there was enough room for full travel alongside the fuse with the current placement and may flip the servo 90*. 

RE: 4*120 Build Thread
 

I resolved my goofup without having to move anything I installed so far. Turned out the throttle arm was in line with the motor mount so it would not have worked along the side after all. I flipped the arm 180*, and the link runs right down the middle of the fuse now.  Last item before the tail is assembled is figuring out how to set up the choke since it can't be reached now. <div>
</div><div>Question on inverting the engine though, I flipped the mounts over and mounted the engine on them as though I was mounting it upright, and it looks like the crank is centered on the lines marked on the FW, so is this correct?   Everything fits nice and snug, and I have a Pitts on order for it. Maybe next week it can have its first flight.  </div>