Edwin

My Feedback: (2)

I use the dual clunk system too. Works great and is proven.
Edwin

Sparkie-RCU

My Feedback: (10)

I'm about out of ideas with this stupid GT-80.
I ran it without the exhaust stacks so I would be completely stock.
It has one of the smallest recommended props; A 23 X 10.
I bought another complete ignition system and swapped parts in-between runs looking for the problem, It now has the new one installed.
The most I can get out of it is 6000 RPM with a peak temp of 300 degrees.
This is without a cowl , it may as well be on a big ugly stick.

I'll never do Zenoa again.

Ram-bro

My Feedback: (101)

sorry to hear about your issues. Zenoah is usually a great product. what radio system are you using on yours? I am trying to set up the futaba 14 channel. I think I need a degree or a 5 yr old to do it for me.

FlyerInOKC

My Feedback: (6)

I feel your pain I have a 7C and a 6EX and they are a handful.

Sparkie-RCU

My Feedback: (10)

DX-18
It took a long while to learn the programing portion but I believe I can do about anything with this radio.
I still haven’t experimented with all the features but I tend to learn when I have to.

BTW
I contacted the horizon product support. ( very nice guys )
They said the 24x10 prop is just a “bench mark prop”.
The guys in the shop said a 22x10 prop should be used until 5 gallons of fuel has been ran through it.

So my take away is the prop chart in the manual is B.S.
And so is the statement that “No break in is required”
Also in the manual the motor came with.

Edwin

My Feedback: (2)

Love my DX18. It was tough figuring things out the first week, but once I learned the lingo, it became pretty intuitive.
Edwin

johnnyo

My Feedback: (7)

Sorry to hear your having problems with the GT80. I have the GT80 on my 39# T28, in performs great. Using a 24x8 Xoar, getting 6800-6900 rpm, going to try a 22x10 3bld. (just looks better)
Anyway, is your 80 a factory electric engnition or field conversion. Some of the electronic engintions supplied from off shore have a preset advance and will only function up to a certain rpm. I had a little 45cc gaser that I tried props from as small as a 16x8 to a 20x8 and the max rpm never changed, stayed about 5800. It kinda sounds like that is your issue. The GT80's are turning 9-10k on the GSRA models with no internal mods. As for the temp problem, and the poor rpm. that combination sounds like a timing issue, if the motor is firing to much ahead of TDC, the fuel in the combustion chamber is going to be way to lean at the time the ignition fires. Just some ideas to check.
johnnyO
www.scalercstuff.com

vertical grimmace

My Feedback: (1)

You might be well served to open a thread in the "Gas engines" forums, asking what to expect from a GT 80, and what the best way is to go about handling the engine. Zenoah are as good as it gets from a reliability standpoint. The GT 80 even has it's own Unlimited giant scale racing class. So there are defineately some guys that know how to get them to run well. Picking their brains might help your cause.

branded

My Feedback: (9)

Well, I run a 22-12 mejlik 3-blade on my Ziroli Corsair and get 6800 rpm. I do not have stock magneto, I removed it and installed an electronic ignition. Your repeated reference to temperature says to me that you're running this engine way too lean.

I have been absent from the hobby for about 8 years so I'm racking my memory trying to recall how I set up most gas engines... As I remember it goes like this; (note, regardless of the carb initial setting, this procedure works for all gasoline engines.....you are always starting from a rich run at full throttle and adjusting leaner (HI needle) only to the point where the engine runs smooth. You do not go any further)

1) open the high end about 1 1/2 ~ 1 3/4 turns (favor the richer side)
2) Open the low end 1~ 1 1/8 turns

******before starting

3) Make sure that the linkage opens the throttle fully (butterfly)
4) Likewise, make sure the linkage closes the throttle all the way (important)
5) Start engine (may need some throttle to open the butterfly slightly)
6) If possible, let it warm up a few seconds
7) Go full throttle slowly- open the HI needle until the engine runs RICH, then close HI needle just far enough until it smooths out at HI RPM (Leave it right here, slightly rich)
8) Adjust the low speed needle until you can bring the throttle down without the engine quitting, and the midrange becomes responsive to rapid throttle movements. DO NOT accidentally close off the throttle (recall you set your linkage to close the butterfly all the way).
9) Recheck the HI SPEED- once again, favor the rich side and then close off just slightly until it's running smoothly, and no more.
10) Recheck the midrange and throttle response and adjust the LOW speed needle for smooth transition
11) Once you have it running from low to high throttle smoothly then, and only then, should you adjust your linkage for a reasonable low throttle setting (with engine off of course).
Remember to give yourself some 'wiggle' room so that your TX trim can increase the idle if necessary and that if you wish you can kill the engine in the other direction too...

Sparkie-RCU

My Feedback: (10)

I got the first flight in yesterday.
22x12 two blade prop pulls the plane very nicely.
RPM is at 6600 but didn't like the transition to idle , with a small turn to rich the motor performs to it's needs.
Still well below the specs from the factory manual. I suppose some of you may wonder what my problem is.
The attitude may be because I've been an Airline aircraft mechanic for 30 years. I have grown accustom to having parts and equipment perform per the documentation that is published for it. I guess the piece of the puzzle I lost was marketing .
My rant is over and I appreciate all the help you guys posted .
I'll continue the thread in hopes to help others.

vertical grimmace

My Feedback: (1)

You may wanna try going down in pitch. Maybe a 22-10 or a 23 -8. It seems that 12 pitch is kinda high for a model like this. As you know, disc is more efficient thrust than pitch, and more appropriate for a model such as yours.

Sparkie-RCU

My Feedback: (10)

I have a 22x10 in the flight box.
At the field I was told by other GT.80 owners that the 22x10 it would lack in the top end after the prop unloads.
The 22x12 did reduce the static RPM by about 150 but at 6500 I figured it might go to 7000 by the time it unloaded.
In short they said the zinger prop (22X10) is trash because it flexes and the 22X12 prop did better much better on his Corsair.
I will continue to experiment with the props but now that it has flown I’ll be tweaking CG and control throws.
Thanks for the suggestion 23X8 is on the list now.

Sparkie-RCU

My Feedback: (10)

After several high speed runs I got a feel for how the model responds to the torque.
Very little rudder needed. So the shims used on the fire wall was right on the money. ( taken from another thread)
The tail comes up at the slightest touch of the throttle so I knew I had a nose heavy model on the runway .
After the wheels left the ground the nose heavy condition was confirmed , full trim nose up was needed before it would fly hands off.
I went with the suggestion that the CG was off by 3/4 inch ( posted elsewhere) My computations came up with 1 1/4
I'll cover this later.
After about twelve orbits I started with approaches slowing it down a bit more each time.
When the wheels touched down I was ready for the nose down pitch associated with a nose heavy model but I still overcorrected resulting in one bounce.
Once I get this CG thing corrected I'll have one fantastic flying plane. A real predictable ***** cat.
BTW- the throws listed on the plans are will get you past a test flight. The aileron throw is a tad high but dialing it back is better than needing more.

vertical grimmace

My Feedback: (1)

Your flying buddies are right about the Zinger prop. Those are considered paint stirrers. When I first got into the big gas engines I wasted a lot of time and money on props. Your best bet is XOAR or Vess. If you have the coin, then go with Mejlik. I only fly Xoar props thoguh as they are easily available and fit my budget. They do not flex, and seem to give the best thrust of anything else I have tried.

Sparkie-RCU

My Feedback: (10)

I was told if you know what your motor temp is you don’t know what you are doing.
This guy nailed it on the head. I had no idea what is should be but I knew it was much higher than any of my yard tools. (175 degrees F)
The motor manual stated that if the motor is to be enclosed baffles are needed. Nothing about how much and where to direct the air.
Back to the weed eater.
He entire cylinder is covered hogging any cooling air it can get. How to apply that to the model.
I wrapped the cylinders with press and seal sandwich wrap plastic.
Rolled out some modeling clay to ¼ thick and pressed it against the cylinders .
After repeated cowl fits and adjustments I had a shape I was happy with.
The clay got a coat of the sandwich wrap and I started laying up fiberglass over it.
There was a struggle to get them off but they fit like a glove.
A simple zip tie holds it to the base of the cylinder and holes was cut to match the holes in the dummy radial engine.
My cylinder temp went from 260 to 190. This was not measured with a gun .
I clamped a thermocouple to the base of the sparkplug and read it on a Fluke meter while the engine ran.
Great results in IMO.
4 flights later and I have no cracks in the baffle so I think I’m done with this “hump”.

Sparkie-RCU

My Feedback: (10)

I know the solid resin motors have much more detail but you have to consider their weight.
I tend to go with vac formed plastic simply because I can make them .

With a little paint and aluminum pieces it does the job.
the ignition ring was made with an aluminum tube bent around a spray can and spliced. Very small screws hold it in place.
the push rods and ignition wires are held in place with a dab of silicone on the back side of the motor face.

Sparkie-RCU

My Feedback: (10)

Sorry about not keeping up with this thread, My job with the airline and what has turned into a second job ( parkflyerplastics.com ) has kept me away.
Production runs on the kits and the many parts I sell keeps me occupied during the building season.

I did have time to work the Dauntless and kept up with the photos.
I doubt I can show them in order though.

Sparkie-RCU

My Feedback: (10)

The tail gunner may be the most noticeable feature about the dauntless.
I took about two weeks scratching the gun and I think it paid off.
I started with the barrel and if you have ever tried to drill holes in an aluminum tube you would know why a drill guide was necessary.
There was several failed attempts at it but once I got the sequence down they came out nice.
Alignment is every thing here.

The gun its self was made with a block of Bondo body filler. Cuts and sands well, loves super glue and paint.
The trick here was to cut and shape two pieces at a time to ensure they would be the same.
Lots of fit checks too!


Now I have a gun but no ammo

I took some time to try to cast plastic bullets and it simply didn't work due to their size.
The only solution I could see is machining them from brass, good god what a chore!
if that was not hard enough I had to bind them together with spider wire fishing line.
they came out great though.

Sparkie-RCU

My Feedback: (10)

The tough part about the ammo box was the brackets that hold the wood feeder pins at the opening .
Tiny parts are a pain to keep from using too much glue.
In the end I had to move the box aft because it didn't align with the belts as well as I wanted.

Sparkie-RCU

My Feedback: (10)

This plane was built like a tank.
Without the rivet details you are just wasting your time.
I know it is the lazy approach but I am fond of using hair combs to apply my rivets.
Normally I hit the dollar store and buy a pack of ten or so and go to work cutting out teeth.
Having several rivet per inch tools is necessary to make it look convincing.


I wont bore you with the masking and paint application.
Patterns, tape and masking paper ,bla, bla

FlyerInOKC

My Feedback: (6)

Great job Sparkie! And thanks for the update. I'm sure I'm not the only one here happy to hear parkflyerplastics.com is thriving!

Sparkie-RCU

My Feedback: (10)

Since we are on the subject ( website)
When I ordered the windows for this model I had every intention of using them.
However when it came to fitting it on the model the window line at the windshield was going to force me to make the panel line way too high.
(Shown with masking tape.)

As it is I had to fudge a bit with the window I made since the window line should be flush with the top of the plane.
eliminating the bottom panel line in the new tooling made it much better.
When it came time to cut the canopy into the five pieces I found that getting them to overlap so I could open and close them would be impossible.
So I made a window set for my plane and they are offered as individuals or as a set on the website. Parkflyerplastics.com


I used brass square tubing to make the slots for the windows to slide in and the fit is very snug.
At the aft end there is a piece of bent steel bonded to the window that holds the last window down since it can tip like the real plane.
I was worried that it may suck off in flight.
You can see the allan wrench stuck to the embedded magnet in the last shot along with the magnet that will hold the gunner in place .
The two tracks for the back windows couldn't have worked out better.

Does anyone know if the model handles any different with the windows open?
to date I have only flown with them closed.

FlyerInOKC

My Feedback: (6)

WOW! Just seems to fit it.

Sparkie-RCU

My Feedback: (10)

Lets take a step back to the fuselage construction.
I took two aluminum straps and made them a part of the light ply frame box.
The screw holes was reenforced with aircraft grade ply wood.
The straps are attached to a cable /clevis arrangement like the full scale plane.
It is a bit oversize but it is used to lift the model for storage like they did on the carriers.
Yes, they stored them on the ceiling.
This feature is also used at the field to check CG..

Sparkie-RCU

My Feedback: (10)

I did what I could about the instrument panel.
A little drawing on the computer and some plastic work and it was ready.