samparfitt

My Feedback: (43)

Re-build (cont)

I used 80 grit to sand the finishing resin until a satin sheen appears on all surfaces.
I then removed the masking tape and sanded with 220 to get a smooth finish and remove the edges that the masking tape left behind.
The damages areas then, were re-masked using masking paper to protect non-damaged areas.
I used to use the 'house brand' 2-part epoxy primer but the local auto paint store now stocks PPG JP375 and JH3770, which they said is the same stuff. Since the area to 'shoot' is small, I just used my air brush. Only a very small amount of primer was prepared and the air brush allows covering small areas without a lot of 'over spray' and runs.
For me, primer is mandatory as it shows all the imperfections that I missed, no matter how long I sand the area to make it smooth.

samparfitt

My Feedback: (43)

Re-build (cont)

A couple dings on the stab from large weeds needed some easysand.
Easysand also applied to the dings along the belly pan (bummer: all that natural weathering from the scale exhaust is going to get painted over!).
One corner on the bottom of the cowl was broken off. Epoxy fixed that along with using some heavy duty FG cloth from the local auto shop to mend some stress cracks in three other locations.

samparfitt

My Feedback: (43)

re-build (cont)

The pin hinges on one flap were all snapped off so I had to drill them out with an 1/8" bit and then a round burr bit to get the needed diameter. Yellow aircraft is the only manufacturer that I know of that sells black pin hinges which blends in nice with dark colored planes without having to paint them.

Some solartex was used to cover several tears on the underside of one elevator.

One of the servos for the elevator had to be replaced. It appears the motor burned out and, also, the circuit board is toast. (Most people don't know that smoke is used to power circuit boards and once you let the smoke out of them, they never work again!)

samparfitt

My Feedback: (43)

Re-build (cont)

Bottom white (actually a creme color) 'shot' with an air brush, completed this evening so it'll dry overnight and be ready for the dark blue.

samparfitt

My Feedback: (43)

Re-build (cont)

Rivets were re-added over the damaged area. A ruler and jewelers screw driver were used to make panel lines.
The areas needing painting were masked off using the next (or best) panel line as a demarcation for the masking tape.
A touch up gun was used for the large areas whereas the air brush for a couple small areas. The primer was over sprayed 3-4 times until it matched the original paint and then the entire area was covered, last.
I've been using aluminum tape for fake hatches, etc, thinking I would later come back to weather the paint and have the aluminum show through. I used blue, low stick tape over the area that needed to be masked but, after painting, some of the old paint pulled off from the aluminum tape.
To solve the scraggly line, I used an xacto knife to cut along the edge of the ammo hatches and used some masking tape to remove all the tape from the hatches, giving the impression that these have been replaced, but not yet painted.
I never have any problems with paint lifting off the 2-part epoxy primer but I need to roughen up the aluminum tape before 'shooting' it with paint.

samparfitt

My Feedback: (43)

Re-build (cont)

Continued from previous post:
The cowl is the last item that needs painting, using the light blue.

Scott Prossen

Nice quick work there Sammy! Looking forward to seeing you at Macs. Only two weeks away. My buddy Doc will be there with his 1/4 Scale scratch built 120" Hellcat. We'll all have to line up our 'Cats for a group photo!!

Drive safe!

samparfitt

My Feedback: (43)

Yo Scott,
Sounds good.
I'll leaving the Tuesday before to maximize the long trip and get a lot of flying done.

===========
Re-build (cont)

Well, the plane is done but the engine isn't!
There was no 'sputtering' so I moved the sensor closer to the fly wheel and got a 'kick' when I slowly turned the prop.
The engine 'sputters' for several turns and stops. I rebuilt the carb and checked the plugs and they are wet but the same results.
I checked the ignition switch and battery but still no luck.
The engine was converted to electronic ignition using CH ignition by the previous owner.
Looks like I'll have to send it to B&B specialties, assuming they work on GT-80's.

OldScaleGuy

My Feedback: (2)

Sounds like a failing ignition module. Is it trying to run on both cylinders or just one?

samparfitt

My Feedback: (43)

OSG,
I took the plug off of each side but it wouldn't 'sputter' so I'm not sure but I'm also leaning toward that.
Contacted Denny via email at B&B and told him the symptoms.
Tried searching Horizon's web site for cost of ignition for the new GT-80's but no luck on finding them.

Check6

My Feedback: (427)

Hi Sam,
Another awesome build!! I will be building one of these with a glass fuse. Using a GT 80. What is your all up weight and how much weight did you need for balance.
Thanks,
Fred

samparfitt

My Feedback: (43)

Fred,
I don't have a scale but I'm guessing in the low 40's. With the short nose on the fuse, I used about 8-10 lbs. The GT-80 flies it but it takes a couple 100 extra feet to get her off the ground. A scale take off is needed: After take off, no steep climbs, neutral elevator, gear up quickly and gain speed and gradually gain altitude. Once on the back side of the circuit, she has enough speed.
Drill out the baffles in the stock mufflers through the exhaust pipes for extra RPM's. I used a Mejzlik 24X12 to get max RPM's (about 6500).
I have two elevator servos in the stab, full Dbalsa cockpit and a sliding canopy so mine is going to need extra weight up front.

samparfitt

My Feedback: (43)

Engine:
Electronic ignition test and sensor test:

I talked to Adrian at CH ignitions and he told me how to check the ignition and the sensor:
http://ch-ignitions.com/index.php

The wires going to the sensor is black, red and white: the two outsides are black and white and the center is red (do not touch the red wire or the ignition will be damaged).
I cut a paper clip in half and put half of each paper clip (hard to find those, now!) into the two outside connectors and laid the two plugs on the cylinder heads and got sparks on each plug when I momentarily touched the two pieces of wires sticking out of the two outside connector pins. Then, I re-connected the sensor and it also worked fine when I turned over the prop.
Again, I tried to start the engine but it only sputters so the 'guts' need fixing on the engine.
I don't know if all sensor wires are connected this way but it worked on the Zenoah GT-80 with electronic ignition. I also didn't know that both plugs fire at the same time.

Check6

My Feedback: (427)

Hi Sam,
Thanks for the info. Wow 10 lbs. of lead to balance. I remember when The whole 60. size fighters weighed 10 lbs. RTF and we thought that was heavy. LOL You have to balance them. I was hoping around low 30's in weight but we'll see what happens. I'm thinking of making mine a 2 piece wing where the break is directly in the middle of the center section. This keeps all the flaps and landing gear in one section and eliminates the problem of the spar tubing going through the landing gear well. What do you think. This will be similar to what Meister does with there wings.
Thanks,
Fred

samparfitt

My Feedback: (43)

Fred,
Like I always say, there is no 'right way' to build as we build to meet our own needs and what we are comfortable with. At my last fly in, I was just watching a pilot assemble his Meister ME-109 where the wings join in the center. If you don't put all the 'junk' that I put on mine, you should be able to reach that weight.
I extend my fuse nose (on wood fuses) and engine out farther than the plans to help on reducing nose weight. No one notices the extra length.

OldScaleGuy

My Feedback: (2)

Sam,
Have you checked the screen inside the carb?

samparfitt

My Feedback: (43)

Yep, did that when I rebuilt the carb.

samparfitt

My Feedback: (43)

Engine:

I think I've found the problem.

The sensor mounting got pushed back when it hit the fence.
I used adjustable pliers to gently bend the mounting and the engine seems to run fine, now. The plane was upside down on a stand so only a quick 'run up' and no tach'ing: will do a more thorough test, later. This still doesn't answer the initial problem of why the engine died while flying! (not sure if I'll ever solve that!).
(before/after pictures)
I re-binded the receiver as some servos were 'jumping' across their full movement range when I turned on the receiver.

p51tom

My Feedback: (1)

Hi Samparfitt,
I am building a Don Smith 86" Hellcat and want to add panel lines and rivets. I hate to paint markings so I am very interested in your method of using decals. I think you must have used water slide decals. Did you use any kind decal setting solution or a heat gun to let the decal form around the rivets ? Also do you have raised rivits on the Fus? Where did you get you decals? How did using the wind to close the front doors work? Thanks showing your build, the Hellcat looks great.
P51Tom

JPate147

Hi Sam,

I remember on those old style pickups (sensor) that turning the magnet inside the sensor housing can have an immediate effect - good or bad You may want to try testing the engine as before, while turning the magnet. It may spark stronger and better than it is now.

Regards,

Jerry

samparfitt

My Feedback: (43)

Jerry,
I'm not sure what you mean by turning the sensor magnet as the magnet is firmly imbedded in the fly wheel. It's possible to turn the sensor.
.
.
.
After thinking about it, I'm assuming you just meant the sensor: I wasn't aware that it's orientation is critical as the magnet approaches it but I'll try to see if it rotates. The sensor is inside a black tube and there is only one set screw mark on it so the tube hasn't rotated but maybe the sensor is rotating inside the tube.

===============
Engine:

Well, all went well, at first!
The engine started and I adjusted the low/high needles as the low needle needed to be open as the engine was hesitating when 'throttling up'.
After I had the engine running pretty well, it died. I figured it was no fuel since I didn't have much in the tank, so I added more but the engine went back to it's old habits of just sputtering a few times.
I tried another battery, again and tested the spark plugs against the cylinder heads and they both were sparking and there was fuel on the plugs. I tried some new plugs and she ran for about 2 seconds and died. I also replaced the tubing from the crankcase to the carb.

I called up Adrian at CH ignition and he says that maybe my timing is off.
He says he has a timing wheel on his web site that I can print off with instructions.
He said timing should be 28-30 degrees.

I'll try that tomorrow as it's getting late.

samparfitt

My Feedback: (43)

Tom
I used water transfer decals from Major decal for the stars-n-bars.
http://www.majordecals.com/
I just let the decals dry naturally and then I over sprayed the decals with minwax polycrylic satin.
I removed the decals from the water before it separated from the decal paper to insure the glue didn't get washed off.
The rivets are a combo of flush and raised rivets.
You'll have to look at my thread to see where each goes: I think the raised started at the cockpit.
The wind works great on closing the hinged gear door on the wing.

All Day Dan

My Feedback: (5)

Sam, this video has helped out a lot of guys. Dan.

JPate147

Hi Sam, yes - I was talking about the magnet in the sensor. Sometimes, that sensor can get too close to the flywheel, and it will be shaved off in about 2 revolutions. I have an old 'tester' from C&H that allows you to test the sensor and the ignition without running the engine or connecting the sparkplugs. It's just a small black plastic box with a red LED and two sets of wires coming out of it. Maybe someone has one for sale. If you can't figure it out, let me know and I'll send you mine to see if you can pin down what's wrong.

samparfitt

My Feedback: (43)

Jpate,
Thanks for the info. Yeah, I probably put the sensor too close to the fly wheel and it may have been damaged, I can have Adrian send me a new one: can't be too expensive for a sensor.
First, I'll try checking the timing.

All day dan;
I assume you see the missing attachment on your post.