I am thinking about putting together a 4* 60 and perhaps? shortening the wingspan by one rib bay on each end, and adding more rudder athority by making it larger or of the balanced type. For engine I am thinking of a ST 90, mounted at such an angle that a mousse can setup would come out right down the bottom center of the fuse, right between the landing grear. Or perhaps I would put a new Saito 125 on it.

Any 4* 60 ideas or stories? Thanks!

Ernie

To mount a ST 90 at a 45 degree down will require a little different thinking as far as a cowl goes. Part of the strength of the original firewall is gained from the cheek plates. So if they are removed, you need to pin the F1 bulkhead or something?

Reduce the size of the vertical stabilizer by the amount of your counter balance. Do not make the rudder much higher with a counter balance across the top. Cut the counter balance part mostly into the existing fin. Look at the vertical stabilizer/rudder on a Venture 60. There is a Venture 60 site on the web. The Venture is a later design take-off on the Four Star. Still not 3D but has better knife edge characteristics.

The rear of the turtle deck could stand to be raised a little for more stability.

The landing gear is normally too far forward. As a minimum, place the gear so the taper part points to the rear. The forward gear tends to want to bounce the plane back up into the air unless you are completely stalled at touch down.

i increased the length of the elevvator and rudder by about 1.25 inches and added ounter balances to the end...
no change to the stab lengths...

flys great... nice flat spins, water falls... very fun

Why would you want to reduce the height of the vertical stabilizer by the amount of the added counter balance? I added 1.5 inches to the length of my rudder, and 1/2 inch counterbalance on top, and it flies great. I dont see the point of the extra work, unless it's purely cosmetic.

As far as the other mods go, shorten the wings by one bay on each side (if your building from the kit, I would also consider sheeting the wing leading edges back to the spar) and lengthen the elevators by an inch or so. Some guys rework the canopy by cutting it down to a more form fitting shape, but I personally like it the way it is. Get rid of the stock tailwheel and install a Sullivan. This is just a start, and you are pretty much limited by your own imagination.

Ernie,

I've had 2 4*60s, both were bashed into a Kawasaki Tony, but with shorter wings. Both flew great.

I would definitely cut off 1 rib each side. For rounded wing tips, I cut off 2 ribs and added about 1 1/2 back with the round tips.

It needs more rudder, at least an inch. It can also use more elevator, but the rudder is woefully small. I moved the servos to the rear.

I moved the gear to the wings. Straight as an arrow take off with no rudder correction. I used ply doublers on the forward half of 3 ribs and installed landing gear blocks. I also used 3/16 wire.

Both my planes had .91s. The first had an OS .91FX. The stab came off and totaled the plane. My second had a Magnum .91XLS with an Ultra Thrust muffler. Unlimited vertical. Rotate on take off and go up forever.

If you have any other questions, drop me an e-mail.

W8eye, interesting observation about foreward gear making for bounce. I am aware about that making for the erratic takeoffs and ground loops though!

Ed, you get the prize for the most re-worked 4*'s! Also, the Magnum 91 XLS is a powerhouse I bet, especially with the Ultra Thrust muffler. I bet a mousse can would be awsome too. That engine is very overlooked I'll bet.

Lots here for me to look back over. Thanks a lot guys. You are all the best.

Ernie

The wing is a Turbulator design for better low speed lift. If you sheet the leading edge back to the spar, you will destroy the original design intentions of Bruce T.

Enjoy,

Jim

Did Bruce Tharp design the 4* series for Sig?

I suppose with a sheeted wing, we could add a turbulator or "trip strip" with a couple of layers of thin tape or striping.

Does anyone want to know what a turbulated airfoil is?

Ernie

sheet your turtledeck..

http://www.rcuniverse.com/forum/How_...2465127/tm.htm

Not to burst your bubble, but who cares about the "design intentions" of Bruce Tharp? I know full well about the wing design and what it is for. But, the fact is, sheeting the leading edge does a lot to get rid of one characteristic that alot of people dont like about the Four Star to begin with... the tendency to float forever on landing, BECAUSE of all that low speed lift. That, coupled with taking one bay out of each wing will make this plane land exactly where you want it every time, instead of floating halfway down the runway. As far as the design goes, the "design intentions" never included cowlings, enlarged and counterbalanced control surfaces, main gear relocated out to the wings, shaped wingtips, etc., but we do those mods all the time now, dont we! Besides all that, if you go to Bruce's website and read his description of the Venture 60, it states that the leading edge is not sheeted primarily to reduce weight and speed build time, and that the turbulator spar design "MAY" increase low speed lift and handling.

The Four Star 40 was designed by Bruce. He then did the 120. Then left Sig to do his own stuff. He brought out the Venture 60 which he claims to be a improvement over the Four Star.

I think Claude McCulloch designed the Four Star 60? Cannot remember? The 60 was the last of the three to come out. The proportions of the 60 are a little different than the 40 or 120.

There were some planes that preceeded the Four Star 40 that led up to the idea to bring it out.

There was the Ace 4-40 or something like that which was more or less like the Sig Mid Star. Then there was the Ace Bingo 60 and Big Bingo 120. These planes reminds one very much of the Sig Four Star series. These planes had more of a Doc Mathews origin. The airfoils were thinner and less symetrical than on the Sig planes. Balsa USA brought out planes like these 10 years or so ago. They have since dropped by the wayside.

Low Level, your the one in a bubble? You are the one that dreams of spectator applause after you fly?

I have no problem with my Four Star 60. It is not modified except for moving the wheel position aft. It doesn't float half way down the runway. I approach at the correct speed and it lands like any other plane.

I'll fly my plane the way I want to and you can fly yours all you want and I will not care what you do.

There are other problems with the design from a aerobatic point of view that you have not begun to address.

Enjoy,

Jim

whatever, Mr. expert, sir... Mine flies just fine, will do all the maneuvers I need it to do, and lands perfectly. And, I could care less about spectator applause, dont know WHERE you got that from. This thread was started by a guy who wanted to know about mods that can be done, not a pessimistic view of why they shouldnt be done, or that they shouldnt be done just because the designer didnt intend it to be that way. Yes, there are other problems with the design from an aerobatic standpoint. It wasnt designed as an aerobatic aircraft, I'm aware of that, thank you. But, with a few mods, it WILL fly respectable aerobatics, and will perform the IMAC basic and sportsman sequences pretty well. But like you said, you fly yours the way you want, I'll fly mine the way I want. You have a nice day yourself.

Add 1 1/2 inches to the elevator. Also notch the elevator halves so you can get more rudder travel. Make a Cap 230 style fin and rudder. Leave the turtle deck alone. Cut down the stock fin so that it goes from the stock turtle deck and is the same height as the stock fin but cut down the area of the fin. Make a big counter balanced rudder and small fin. I did this and it would do a true knife edge loop easily. Before that I left the stock fin alone and just made the rudder bigger. It worked a little better but not nearly as good as the Cap style fin and rudder.
Put 2 inch airlerons on it instead of the stock set up. Don't clip the wings. For landing it is a floater. Hook up air brakes if you have a computer radio. Program in ailerons UP and it will cause drag and the plane will not float on landing any more. You will also have to program in a little down elevator with the air brakes because the nose will pitch up when you put on the air brakes. Make the elevator bigger because when you land a stock 4 star 60 if you slow it down too much to land it will run out of elevator and just drop out of the air and bounce. With the bigger elevator this problem will no longer exist.

I suggest you do all these mod's and then give it the power it deserves with a 120 2 stroke