Thunder Tiger Pro .25

That's the replacement gasket, Phil. Thanks for locating it for me. I should probably get a spare.

What I need for engine tuning is either some slightly thicker ones to replace the original, reducing the compression, or some much thinner ones to stack on top of the original one. The second option is preferable to me, but I haven't tried the soda can method yet. I'm pretty convinced I don't have whatever I need to do a good job. Ron may be right, that it will seal fine, but I worry about a lick of flame working at the inside edge of one that doesn't fit around the head snugly resulting in a burnt liner deck or head(kind of like when an exhaust valve leaks in a 4-stroke engine). Next time I take off the head I'll show you what I mean. A good description escapes me.

Let's see how my flying goes tomorrow before we take off on another one of my frantic runaway topics that end up with me looking like a doofus again. Thanks for y'all's attention though.
Rusty

Here are the dimensions in inches of the original, which is actually probably a metric component.

roddie wrote:I was at my local Lowes today, they had the .025" copper and also the tin and brass, in the specified thicknesses on their website. It wasn't for the lack of searching though... It was in an "un-marked" drawer in the hardware aisle... near where the hobby items/un-finished wooden knobs drawers are. Did you look there?... or did an associate tell you they didn't have any?

I looked in the slots where they had welding metals like 12x24x.025 aluminum, steel and thicker diamond plate. No copper. I know where you're talking about. I'll look there because I need some copper for a new battery box. But after trying to make a gasket from the .030" aluminum I had, I believe it's outside my tool set or my skill set.

Rusty, I'd add the one you made to the original, and fly it. Then maybe remove the original if needed. Not sayting it right, but I've see guys run four .015 gaskets on their O.S. FP's! The sidewall on a aluminum can is not very thick and i don't think your gonna gain much.

remember slightly snug, then little more torque in a star pattern, then more again, twice around to draw head down even.

Mark Boesen wrote:Rusty, I'd add the one you made to the original, and fly it. Then maybe remove the original if needed. Not sayting it right, but I've see guys run four .015 gaskets on their O.S. FP's! The sidewall on a aluminum can is not very thick and i don't think your gonna gain much.

Mark Boesen wrote:remember slightly snug, then little more torque in a star pattern, then more again, twice around to draw head down even.

That's an idea, on top of the old one it would be safer. Four, really, that's .060". I had assumed the two might reduce the compression too much, but that'll make mine .040"(mine is probably .015 instead of .016 too). This engine isn't much different from an FP. I'll try it in the morning. I'll put it in before my first flight.

And yes, I'm keenly anal about cross tightening. Usually at least 3 times around, checking for any stiffness as I go. Thanks for checking that I knew that.

If that is too thick I have some .001, and .003 brass shim stock if you are interested. It is water damaged and discolored on the edges. I can pop a couple pieces in an envelope with a stamp or two and send them off.

Phil

lol, i knew you probably knew, but i threw it out for the new!

I had Lew Woolard redo a FP40 for me and i almost think he almost hogged out too much, it was amazing how much material he ground out of the head, but again he also reported the cylinder as well.

i don't think that thin of stuff will do much good, most use .010 or .015

I shall file a report on how my extra .025 clearance works.
I'll video at least one or two flights since that's the only way I can count lap times. My Walmart stopwatch is a worthless POS. The buttons either don't click or click twice. I almost crashed one day trying to fly and work the stupid thing. If it flies slow enough, I should be able to complete the pattern pretty well. Hell once in a while I can do it at screaming rocket speed.

Going to bed now. Up at 6, slam some coffee and toast, slap the extra shim in, load the car and go flying. Hopefully I won't lay awake flying patterns in the bed. I hope to be done well before noon.

See ya later, dudes.
Rusty

good luck buddy!

I'm back. Wearing a few bandaids and my knuckles look like I've been in a fist fight. I really need to use a chicken stick.

I got about six flights. The TT is much more manageable with the lower compression. even with the extra ,025" clearance it has a healthy pop over. I guess I'll post the flight report here in the Thunder Tiger thread since that's what it's gotten to be all about now.

For the first flight I tried a 9x4 MA prop and it ran good, but it went richer about the time I was pulling into my overheads and I lost the lines and aborted. Maybe the panty hose was getting clogged or something. I've never had it richen up during a flight. I suppose the needle could have moved. Anyway, the second run I went 1/8 turn leaner and it was too lean, so it's very picky. This is where dropping to lower nitro might help. I'll order that tonight.  After those two flights I tried the 10 x 3.5. With the big prop, I can't leave it running rich long enough to pick up the lines. I had that trouble with the TF wood 10x4 too. If I set it so that it stays lit long enough, she's bust ass lean in the air again and coughing out in every loop. Nothing but aborts with those.

So I decided to try my MA 9x4 which I had clipped the tips on. It was running pretty good but I shouldn't have been flying by then. I could barely walk straight. I did about like the first flight but the camera ran out of juice and quit. Pretty much a carbon copy. My usual squares were loopy today and I think I've learned something. This plane is not going to perform at or over 5 seconds. It needs more speed to stay tight, so if I'm going to compete, it's going to have to be in the high 4s. I was flying just over 5 seconds today. I wanted to try it without the panty hose, since it was choking a little near the end of the patterns. I wish I had more endurance because I wanted to give it another try and get it right, but I decided I was more likely to wreck it, so I packed out after 2-1/2 hours of stooging... figuratively and literally. Other than my aborted overheads, a HUGE disappointment, I flew some decent patterns. Still too tight sometimes, but passable for a beginner.

Next time out, it's 9x4s and dialing them in. I'll crunch a movie tonight.

Rusty

PM sent

Today's movie is cooking. As soon as it's done I'll shoot it up to the tube.

I had a minor glitch coming out of my inside loops, almost forgot to flip inverted. That's the kind of crap that happens when your mind is on the engine rather than the pattern. I flew the outsides blind, looking right into the sun. I was really proud of my loops on the last flight with the APC prop, but the camera didn't finish the flight, so it's not included in the movie..

Loose lines is why I bailed on the OH8. When they went slack I caught it and turned out early. Looking back, if I had just waited, it might have tightened up again after coasting over the top and I could have done the maneuver. Too late now. There was almost no wind today and that was a first for me. I've grown so accustomed to using it, I freaked when I didn't have a tailwind to carry it over the top. I think I need to fly this plane a little faster than I've been striving for.

When the movie is up in about 45 minutes, it'll appear here:
https://www.youtube.com/watch?v=1x4JTuNm450&feature=youtu.be

Rusty,

Your loops are opening up nicely and your horizontal eight looks very pretty. I think the 9x4 is your prop. Not sure what was going on with the 10" prop, but the engine wasn't happy at all.

Almost there man, keep at it. You have the skills down, now If you could only get a clean run!

Thanks for the video.

Ron

A different way to slow it down is to make the lines longer. For trimming purposes you can use 65# spectra and tie up a pair each of 1 ft, 2 ft, and 3 ft lines. Clip them in and see what it does. You can add up to 6 ft in 1 ft increments.

If you find a significant improvement it will force a purchase of new lines though.

Phil

RknRusty wrote:
Hey that's nothing, I know a guy that can flip start a .46 without a glow driver!

That's nothing. We once had a Prime Minister whose wife could kick start a Jumbo Jet  .

dinsdale wrote:

RknRusty wrote:
Hey that's nothing, I know a guy that can flip start a .46 without a glow driver!

That's nothing.  We once had a Prime Minister whose wife could kick start a Jumbo Jet  .

Hey, I knew a girl that could suck start a Harley Davidson.

But back to being cereal,
After flying Thursday I hadn't had time to inspect the engine after running with my home made head gasket. I was worried a little about blowby burning the top end since the gasket didn't fit perfectly. But as per Mark's suggestion, I stacked it behind the original gasket, hoping that would seal it up. It did. I took it apart today and it's all clean. And with the added .025" clearance it's not as aggressive and should allow me to fly manageable lap times, so now when I fly my last two practice outings before I take it to Stuntersville, I can concentrate on pattern flying rather than diddling with the engine. I may try some other types of the same size prop, 9x4, but that's the only changes I'll be making. I'll be going out to the field Thursday and hopefully one more time next week.

roddie wrote:So Rusty, are you now at .025" total thickness? (by adding an .010" to the stk. .015")

No, Rod, I added .025 to the original .015, so I'm at .040" clearance. I ordered a pair of stock gasket sets but won't have them in hand for a few days. If after I fly some more, I think it's too under powered, I can drop it back down with one of those to a clearance of .030".

I mentioned above that I wouldn't be changing anything except maybe prop brands from here on, but I neglected to say I had ordered 10% fuel. So that may require a gasket swap. In my usual way of complicating matters.

Note: I posted earlier that my stock gasket was .016", but that was with my old beat up dial caliper. Mark then quoted the size of the OS shims at .015", so I'm guessing that's the thickness of mine too. After all, the TT is an OS knockoff.

The over complicating Rusty

My spare set of bearings came in the mail from Boca Bearings, free shipping too. The old ones seem to be trouble free still, but I couldn't help worrying that they had gotten dirt in them a while back. So I'll have them if needed.

I also got my Sig 10% fuel today and added 2% more castor and a couple of drops of Armour All. My .015" head gaskets will be here Friday. Meeting Wayne at the field at 10:00am, and just got an e-mail that it's freshly mowed. So a flight report will follow. I'll take it back to the Shoestring thread since I think I have the Thunder Tiger under control now.
Rusty

I got my two new gasket kits today. They include one head shim, venturi gasket and backplate gasket. When I first got the thunder Tiger, the sprinkler style venturi was loose enough that I could spin it with my fingers. The compressed gasket and spraybar hold it in place. I stacked a smaller Norvel o-ring under the gasket and it's very snug and tight, so I'm not going to mess with it before next weekend.

I'm going to remove my home made .025" head gasket and put these two in with the original one. It will increase the clearance by another .005" to .045". Hopefully that'll only mean a slight needle adjustment and no noticeable power loss. But I'll feel safer using uniformly thick shims instead of my comparatively wavy hack job. If the engine doesn't like it, I'll go back to my home made one.

I don't have time to complicate things this week. This time next week I'll be in Stuntersville. Looks like it's a big event. It took me a while to realize how well known this gathering of flyers is. I'll probably practice one time this week, and then some on Saturday up there.