Showtime 4D 90 problem
 

Flew my ST for the first time yesterday and man what a handfull. The wings rock back and forth for no apparent reason. Also while flying it will go to knife edge on either side with no stick movement. The servos are Hitec 645 metal gears. The wing rocking I could understand if I was trying to harrier but it does this just flying straight and level about half throttle. I don't think it's a hit because nothing else changes. The C.G. is right on the money according to my cg machine, I've checked it several times. What could cause this?

Also the plane will not take off then all of a sudden bam it shoots straight up in the air. So far I'm not impressed at all with this plane. It looks good but flies like crap. Anyone have any ideas? Thanks!

RE: Showtime 4D 90 problem
 

It might be tail heavy even though you are at the recommended CG. I had the same problem with my Funtana90, I had to move the CG up about a 1/2 inch, now it flies much better.

RE: Showtime 4D 90 problem
 

If the plane shoots straight up on takeoff then the cg is way to far back. Try balancing upside down.

RE: Showtime 4D 90 problem
 

Plane was balanced upside per the manual at 7 7/16" on a Great Planes CG machine. I may just have to add some nose weight and fly it again.

RE: Showtime 4D 90 problem
 

keep us posted i have mine balance per the instructions and she flies very well inverted

RE: Showtime 4D 90 problem
 

The Showtime elevators are in line with the wings and thrust line and it has a long tail. This keeps the plane on the runway until the take off speed is reached and causes the jump -- not necessarily the CG. Others have reported this in the other thread. It still kind of does it for me but not as bad since I used some taller tires, raising the angle of attack at the take off position.

RE: Showtime 4D 90 problem
 

dbl post

RE: Showtime 4D 90 problem
 

My old Funtana used to "HUG" the runway and then jump straight up..
ALSO had very BAD prop clearence...
Once in the air it flew normal..

Installed a 1" spacer above the main gear and larger wheels and is
perfect now...

I think the Showtime has that short gear setup also..

RE: Showtime 4D 90 problem
 

I Have Both Showtime 90 and Showtime 50. My 90 has OS 120 AX in it and I balanced it 1/4" forward of CG Recommended in the Instructions. It Flies Super and Very Stable. I didn't install Wheel Pants so I can land on Grass or asphalt. Almost needed zero Trimming. I love to fly Only with SFG's installed. Rock Solid performer with CG where I set it at 7 1/4" back from root of front leading edge. I set 2 Dots on Top & Bottom of wing in bright Orange and Green Repair Mono Film with strong adhesive on it that is made for accenting or Field repairs. Make them with Standard Office Single Hole Punch. Orange Dot I place dead on recommended CG and green Dot 1/2" in front. I Balanced Showtime half way between 2 dots on GP Balancer. Another Change I Did is mount My Engine Upright with the longest OS Extension on the Muffler. I'm Just breaking in OS 55 AX on My Showtime 50 built the Exact Same configuration. I bought it because I loved How Showtime 90 Flies and handles. And Economical to Fly smaller Version. Be Test flying it in next week or so. My E-mail [email protected] and I have Photos I can send if it would help. Showtime 90 My Best Flying Bird of My 10 Bird Hangar. I have New Goldberg Yak 54 Still to test Fly 67" Wingspan with OS 120 AX in it. I like use APC 16 X 4WIDE Props and works Super on 120 Engine with backing of throttle diving or back side of loops so don't over Rev Engine. Good Luck Working Bugs out Your Showtime IT'S GREAT PERFORMER!!! Well worth Time 7 Effort!!!

RE: Showtime 4D 90 problem
 

It also sound tail heavy to me. Did you set the CG machine right next to the fuse?

David

RE: Showtime 4D 90 problem
 

Ya it was next to the fuse about 1/2 inch gap on both sides.

RE: Showtime 4D 90 problem
 

I've had the same problem. I had also balanced it according to the manual. I've laid the CG far more to the front. I putted the 5cells NiMh RX-battery just before the wingtube, it was first mounted at the trailing edge of the wings and I put 150 gr of lead in the nose.

I have to say that in the beginning my showtime flew also like crap, but with the CG more to front I flew very very good. It is a plane you have to get used to...

Cheers, Koenieboy

RE: Showtime 4D 90 problem
 

Anyone experience the Showtime not recovering from Inside snaprolls? I have one that pancaked in becuase I couldn't recover it.I finally full throttled out of it at about 4 feet but needed a couple of more feet.Took out the L.G. and the firewall.I counted 8 extra rotations and tried everything to get it out of the snap...Any ideas?C.G. is at 7.00 inches.

RE: Showtime 4D 90 problem
 

IscarRep
what are your ailerons, rudder, and elevators throws for your snaps?

RE: Showtime 4D 90 problem
 

Well I rebalanced at 7 1/8 and it flys tons better. The only other changes I'm going to make are a smaller tail wheel and more expo on the rudder on high rates. The only bad thing I can see is when it stalls it likes to snap but I can deal with that. Thanks for all the help.

RE: Showtime 4D 90 problem
 

I have well over 20 gallons of glow fuel through my ST-90. I liked it so much, I bought a back-up which is ready to go, just in case. ( I don't fly either of them any more).

The behavior you are describing in your Original Post is nothing like what I have experienced. My CG is WELL behind recommended and the plane is as stable as can be. It rocks like crazy in harriers, but that is because I am still new and learning harriers.

I had to change my servos, hinges, batts and add regs; because the recommended setup is JUNK. You will not be happy with the recommended set-up. This plane needs 8411's and 8611a on rudder to fly right. (or equivalent).

I never bothered to set any rates. This plane is fine at maximum throws and tons of expo.

Good Luck!!!

RE: Showtime 4D 90 problem
 

CAP232CM
site down your ailerons trailing edge. Mine was warped pretty bad. I had to take the trim off the top of the aileron and wet the aileron down with water and ammonia. From here I laid a 4 foot level on top and bottom of the ailerons with 4-10 lbs weight plates on there and let it dry over night. Now I have a straight aileron trailing edge. also check the wings indence with a meter mine were off when I put the plane together.

RE: Showtime 4D 90 problem
 

Same here! The incidence between the wing halves was off by 1 degree and the ailerons are about as twisted as twisted gets. Other than that the plane flies great on the recommended balance point. This was my first Hangar 9 and I'm not sure about the quality. I'm a bit picky but charge me another $50 buck for the "kit" and make sure that everything is right so that I don't have to reegineer the thing on the bench.

...I did fix both problems. There is no way it would fly straight without the "repairs"

RE: Showtime 4D 90 problem
 

A smaller tail wheel? more expo on rudder? sounds strange.....if you were the one with it shooting straight up that sounds a bit counter-productive in fixing the problem...i have a big sullivan tail wheel on mine, which is for airplanes up to 35 pounds, i have a ys110fz in it with a 16 x 6 prop tank is on the center of gravity and battery is behind the wing tube. and my rudder servo is in the tail. all of my rates are very high with expo at 45-60%. it flies awesome, snaps a little but not too bad, it flies knife edge almost no coupling ( lateral balance is good aswell as the one it says in the book ) it flies upside down almost hands off which indicates good balance, servos are 5625mg's except a 5945 on rudder, i use airwild aluminum arms 1 and a half inch ( half arm ) or 3 inches ( full arm ) i think to try to get most throw and they are threaded for the included ball links from the factory which reduces slop compared to having just a hole in the servo arm.


edit: forgot to mention why i said more expo on rudder is strange.....i find ( and this may be just me other people might not think the same ) that rudder is best with only like 10% expo because then you don't have to move your rudder so far to knife edge and the difference between a perfect knife edge and starting to angle upward ( if you can understand that ) is more of a marginal difference on the stick and makes it harder to maintain a good knife edge.

RE: Showtime 4D 90 problem
 

put a bigger tail wheel on it. i put the biggest sullivan one i could find for aircraft up to 33 pounds. it works awesome. and mine is way tail heavy from the recommended point but still flies stable and awesome.

with a bigger tail wheel the amount it has to move to make the wings paralell to the ground is less, so its already at a flying atitude while on the ground. onece it reaches sufficient airspeed to take off it does so looking very smooth and its hard to tell when it lifts off the ground.

RE: Showtime 4D 90 problem
 

I can't imagine that it flew so horribly and then moving the CG 5/16" forward made that much of a difference. The manual was, last I heard, STILL being printed with the wrong method for balancing. It incorrectly said to measure from the wingtip. That has claimed a lot of ST's I imagine...

RE: Showtime 4D 90 problem
 

Can you tell me how many onces the fuel tank can hold on the Showtime 90 because a plan to put my OS 200 in it

TK's

RE: Showtime 4D 90 problem
 

16 or 17 oz fuel tank

RE: Showtime 4D 90 problem
 

I think the 200 would be way overkill for the plane. You'll have to add some weight to the tail to get it to balance without a doubt, and you're fuel won't last long without adding a larger tank, which may not even fit.

There are other airframes that would work better for that engine.

I've heard of people putting a Saito 150 on the ST, and they reported that it was just too much, so the 200 would really be pushing it.

RE: Showtime 4D 90 problem
 

The OS 200u have les weight then OS 120 Surpass and praticly the same dimension



This is the O.S. Max 2.00 FS-200S Surpass Four Stroke Engine.

FEATURES: Ideal for scale and sport aircraft
80N carburetor can be reversed 180° for easy adjustment
Multi-directional F-6010 silencer for mild 4-stroke sound
Two year limited warranty

INCLUDES: O.S. Max 2.00 FS-200S Four Stroke Engine with type "F"
glow plug, F-6010 muffler, header pipe, instruction manual

REQUIRES: Fuel: 5-30% nitro with at least 18% lubricant content
Propeller: 15x12-14, 16x12-14, 17x10-13, 18x6-10, 17x12-13, 18x8-12,
20x8 (break-in engine with prop intended for use on model)
Electric Starter: High torque
Glow starter and field equipment

SPECS: Displacement: 1.98 cu in (32.4cc)
Bore: 1.50" (38.0mm)
Stroke: 1.13" (28.6mm)
Practical RPM: 1,800 - 10,000
Output: 2.9 ps /9000 RPM
Weight: 30.68oz (870g) including exhaust header pipe
Crankshaft Thread Size: 5/16-24


now OS 120

This is one of the O.S. Surpass series of 4-stroke model engines.
The Surpass series is the 2nd series of 4-stroke engines (The 1st series was
the FS series, discontinued and replaced by the Surpass series around 1986-7).
"Surpass" refers to this series gaining 30% more power than the previous
FS series.

FEATURES: Specially developed PD-07 pump
New 70N carb
Ball bearing-supported camshaft and crankshaft
New F-5020 Silencer
Two year warranty

INCLUDES: One Assembled Engine w/Carburetor and #F Glow Plug
One Muffler w/Manifold
One Set of Instructions, O.S. Poster, and Decal
(Mounting Template Is No Longer Included per O.S.)
One additional coarse needle for less sensitive carb adjustment.

REQUIRES: Fuel: 5%-15% nitromethane with 18% lubricant. Synthetic, castor, or
a synthetic/castor blend may be used.
NOTE: Certain four-cycle fuels cannot be used due to low oil content.
However, SOME four-cycle fuels such as the Wildcat 4-Cycle 15%
(CATP9109) may be used because it has 18% oil content.
When choosing fuels for this engine, the modeler must be sure to
select a fuel with at least a 18% lubricant content.
Starting and Field Equipment.
Propeller (see SPECS)

SPECS: Bore: 30.4mm (1.20")
Stroke: 27.5mm (1.08")
Power Output: 2.1 BHP at 12,000 RPM
Practical RPM Range: 2,000 - 12,000 RPM
Weight-Without Muffler: 32.5oz (921g)
Weight-With Muffler: 35.3oz (1000g)
Crankshaft Thread Size: 5/16-24
Valve Clearance: Between .04mm and .1mm (or between .0015" and .004",
measured between the valve tip and rocker arm)
Length: 102mm (4.09") from backplate to the front of the drive washer
Width: 47mm (1.85") width of engine neglecting the mounting flanges
58mm (2.28") distance between the mounting hole centers
Height: 139.5mm (5.49")
Suggested Prop(s): 14x9, 14x10, 14x11, 15x8, 15x9, 15x10, 16x6,
Construction: Aluminum and Aluminum alloys



And th YS 110 is good choice but little heavy for the power it can give 26.9 oz