Thunder Tiger Pro .25

RknRusty wrote:

Mark Boesen wrote:...I must of flipped it 6 or 7 times before it started, went to unplug clip and it wasn’t connected!

Holy crap! Now there are some people I wouldn't believe if they told me that. I wish I could've seen the expression on your face when you realized what just happened.

Popeye, John? You mean the "I'm strong to the finnich 'cause I eats me spinach," Popeye? Hey that's nothing, I know a guy that can flip start a .46 without a glow driver!

Not the first I have heard of this. Happened one hot weekend my family was flying at my Aunt and Uncle's. My Dad ended up crashed in tall weeds, when I pulled it out the wrapped grass must have pulled the engine enough to bump start it. Since Dad still had the control, elevator check, thumbs up and release! This was one of his larger engines, probably a Mccoy .30.

Phil

I bought a couple of OS#8 plugs for $7.99 at the HS and my Sig 10% nitro came today, so first chance I had I went to the shop and tried it out. Yesterday I made a new mount of birch ply and bolted my vice to an old Pontiac front brake rotor. That ought to hold that mother down. My old fuel had been foaming like a hot PBR in July and I didn't have enough to try any anti foaming juice, so I had been holding the tank in my hand, a rather cumbersome affair. So the first thing I did when I unboxed the Sig was give it a hard shake and it foamed too and still had bubbles after 30 seconds. I put two drops of Armour All in it and shook it hard again and nary a bubble, nice.

I needed to learn to crank it without priming the exhaust in case I run it with a muffler(depending on the weight. And I also needed to find the right needle setting area, which I couldn't do before. With the old fuel and plug, if I riched it, it cut off, and it would not really respond to leaning it except to keep chugging along and worry me about overheating it.

So tonight I put 2 ounces of Sig 10% in the tank, blocked the venturi and pulled some fuel into it. No dice, just flip flip flipping. I squirted some in the venturi and got some action. Flooded action but when it cleared it took off running. And the next time it cranked easier; problem solved. And the engine speed no longer changes when I remove the glow driver.

As for needling it I found peak RPM and if I leaned it it slowed, and if I riched it I could hear it slow. It doesn't like to run too wet, it won't really 4 stroke like a Cox will, but it was easy enough to find the point where I could pinch the line for a moment and hear it speed up noticeably. Perfect, that's what I was looking for. From there I can find just how rich to launch the plane. So, it loves the right fuel. Maybe the other stuff just had more nitro than it wanted.

I timed 2 ounces of fuel and it runs 4:50 every time. I'll still buy the 3oz tank in case I ever need more, but I can decide how much I want to fly it with. I may like longer flights if they're not as frantic as my small planes. I'm interested to know if anyone thinks there's a reason not to use a slightly over sized tank. Or maybe it will use the fuel faster in the air. I was running it tonight with an APC 9x6, and I will try others including the 10x4 I bought. I also bought a wooden 9x6 and an APC 9x5 at the HS, to go with all of my others. I have a bunch of props to try out.

So, I didn't fool with the Shoestring tonight, but my day looks pretty clear tomorrow. I want to replace the leadouts and get the wings covered and start fixing the tail.

Rusty,

No reason you can't use a smaller tank for sport flying. Normally the tank size is selected so there is enough to fly the complete pattern. At least that's how I understood it. Keep in mind you will be on 60ft lines so you won't be spinning as fast. You probably won't tire as quick and therefore may enjoy a longer flight time.

Watch some youtube clips when you have time, if you haven't already. It's slow and methodical. 1/2A is much more intense in my opinion. Keep in mind I have only watched the big ones fly and have never held the handle myself.

Ron

EDIT: Since this has been read several times by now, I won't delete it. I'll just add that I am in fact... a moron. There is a head gasket. Upon re-checking, it's there, stuck tightly and blending in with the same colored head material. So, in the words of Roseanne Rosannadana, nevermind.
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I'd like to re-ask a question. I haven't messed with the Thunder Tiger on the Shoestring since my last flight. Just got some new fuel for it, and I bought Sig 15% rather than 10% this time. The manual says it'll run up to 15% with no trouble.

But before I fire it up with higher nitro, I want to make sure of one thing; Is this engine Really not supposed to have any head gaskets?

EDIT: I finally found it, a parts list. It is supposed to have one. Or maybe more but it shows one as item #12. I definitely need to get a couple before I run it again. That might be why I blew a plug early on.

My brother uses a Thunder Tiger in one of his R/C racing planes. He asked me to change the gasket after it was broken-in. I looked for a brass, or copper colored one, and it isn't. The factory gasket is shiny aluminum-colored, and stuck to the head of the engine. I had to use a sharp object=delicately= to pop it free from it's position around the head screws. The darn thing matched perfectly to the machined surface inside the head, but it's there, and about .0015" thick!

Look again, I'll bet you find it. Good luck.

GUS THE I.A. wrote:My brother uses a Thunder Tiger in one of his R/C racing planes. He asked me to change the gasket after it was broken-in. I looked for a brass, or copper colored one, and it isn't. The factory gasket is shiny aluminum-colored, and stuck to the head of the engine. I had to use a sharp object=delicately= to pop it free from it's position around the head screws. The darn thing matched perfectly to the machined surface inside the head, but it's there, and about .0015" thick!

Look again, I'll bet you find it. Good luck.

Hey Gus, thanks. You are spot on, the damn thing is invisible. Re-read the quote(pasted below) from when I updated my last post. I found it. Then I promptly admitted my guilt as being a moron on public display. I was happy to find that I was mistaken and had overlooked it. But thanks. If I hadn't found it, your advice would have bailed me out.
Rusty

RknRusty wrote:EDIT: Since this has been read several times by now, I won't delete it. I'll just add that I am in fact... a moron. There is a head gasket. Upon re-checking, it's there, stuck tightly and blending in with the same colored head material. So, in the words of Roseanne Rosannadana, nevermind.
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If I cut the down pipe off of the larger of these two mufflers and use it as a tongue muffler with a pressure tap in it, will it likely provide enough pressure for a 3oz uniflow tank? And is there any reason to/not to restrict the exit opening? I'm guessing the answers are going to be to try this and that, but I figured I should ask before getting out the hacksaw and drill.
Thanks,
Rusty

The muffler on the left which looks Thunder Tigre or a OS clone. If indeed it's similar to OS, it has that useless cone inside. Others will claim you need it, it does nothing but impede the run. Take it out , the bolt that goes through the entire unit, take it out, JB weld the back half onto the front half with just enough JB weld to cover the part. You just saved a considerable amount of weight. Grind, sand and get rid of all the ribs on the muffler. It will look like the one pictured next to it on the right. The exit holes on OS mufflers have what's known as draft angles on them. This is so when they're casted, they can come out of the mold. The hole you see looking into the opening is MUCH larger than the actual hole up inside. Drill that hole as physically open as possible. Maybe, at that point the muffler will work suppressing noise and possibly run the whole tank without overheating. Drill and tap a muffler pressure fitting if not already on the muffler.

The next option would be to contact Randy Smith and see what fits. Seeing that many of the Magnum's Thunder Tigre, ASP's, are pretty close clones of OS engines, it may just be possible that Randy would have one of his Aeroproducts Tongue mufflers. These are extremely light and well made. The LA.25 sounds to me like it may just have the same bolt pattern as the Thunder Tigre, but Randy could confirm this. His mufflers are about $22 a piece and comes with a fiber washer and pressure tap and the mounting hardware for the muffler. He will also tell you this, that rather than drill more holes in his muffler, carefully open them up to the next size drill bits to assist in your engine runs. Ken

That big one is an OS muffler. I think the small one is a Thunder Tiger. It's completely empty inside. The OS interferes with the LG. Since nose weight is at a premium max, I'll check with Randy. Thanks.
Rusty

I'm trying to tame my TT a bit and want to add a head gasket. The Fox .35 gasket is too big. The one in the TT is really thick at .016". I'd been thinking of using Coke can aluminum, but it's so thin I'd have to make several. I'm wondering if it would be okay to use the metal from an alcohol can. I guess it's steel or some sort of alloy with tin.   Ding... that just gave me the idea to cut up an old perfect fuel tank. Anyway, I don't want any galvanic action going on. Would any of those metals be okay paired with the aluminum gasket?

Meanwhile I'll see if I can order one, but I want to try it tomorrow or Thursday.

Thanks for any input.
Rusty

Dissimilar metals will eventually disagree although, for testing until you get a new one it should be fine.

Ron

roddie wrote:Hey Rusty, for a temporary test... aluminum step-flashing sheet averages .010" and you may even have a pc. laying around somewhere. It's pretty easy to cut, and if you make two, you thicken your stock gasket by .004" (.020")

Got any K & S .005" brass sheet? If so; one pc. added to your stock gasket thickens to .021"...

I could climb up on my neighbor's roof and get some flashing. 
Hobby Lobby might have some thin sheets of K&S copper or brass. I tried steel and took an exacto point square in the safety glasses, so steel is out.

I forgot the Termite guys are coming tomorrow morning, so if I fly this week it'll be Thursday. I'm looking forward to flying slower. I think I can do it pretty well now. Hell if I can complete 1 out of 3 patterns at a hundred freaking MPH(that's an exaggeration), I ought to be pretty good at normal speed.

Try an autoparts, bearing or machinist supply house -- many times they will carry shim stock in brass of varying thicknesses.  Some custom or engine machining shops will also carry shim stock.

Thanks for the search, Rod. A copper .025" might just what the doctor ordered. Lowes is just around the corner from my house. I don't know if a fresh piece of copper will need annealing before I cut it. Couldn't hurt, I guess. I believe slow cooling after cherry red, is right way to soften it. I have a pile of old Cox gaskets I need to rejuvenate like that.

Hi, Andrew, thanks for reminding me, I need to go to the auto parts store too. I'm out of brake parts cleaner. That's the best stuff since zip ties. I'll go there first and check out their shim stock.

 Whoever posted the products on the Lowes site doesn't know .25" from .025"

Copper doesn't matter how it is cooled, once it is heated to red it is annealed. (cherry might be melted) Quench in water and be done with it. It is a "normal" metal, quite unlike the most prevalent "abnormal" metal called "Steel" which can harden when quenched.

Phil

Rusty, if you have a way of giving me measurements, I just may have something here. I personally feel many of these engines share similarities . Hobby People still has Magnum XL head shims http://www.hobbypeople.net/index.php/magnum-head-gasket-xl-25a.html I also feel the OS LA .25 might be an option as well. You would be really better off to make these adj in small increments vs. one . I also feel before changing your fuel you might want to run it using what your currently using. Once the gasket is in place, this could change your duration of run time . Change one thing at a time and jot the findings down. You don't want a over run in the pattern although many turn their heads when your new to flying it. However, the .25 could run a long time on a little amount of fuel. Noting your fuel economy is another important tuning guide as to knowing if your venturi is large enough. For those that use them in stunt, they would know better than myself. This is where the east coast pilots and the west coast pilots differ. I always see differences in venturi openings when discussed on the other forums and I'm quite sure sea level plays an important factor. Where I fly the sea level is less than 20 feet. Ken

Hi Ken, I agree with all of the above. There are plenty of gaskets for the GP 25 available. I'd bet anything they're the same as the Pro 25., so I think I'll get a spare set in case I booger one up. I wrote the dimensions down in the shop, so if I need to, I can give them to you. Also, yes small increments, maybe approximately .005" at a time. I can thin them down between a glass pane and a sanding block. I have a full quart of 15% so that's what I'll start testing gaskets with. I'm at about 300' altitude here. I need to know pretty soon what fuel to order to fly with in Huntersville. I can borrow some 10% to test from Wayne if need be, when he gets back in town next week.
Thanks,
Rusty

Lowes didn't have anything listed on the internet, even at my specific store. So I tried cutting a gasket out of a piece of .030" aluminum I have in the shop. Then I thinned it on sandpaper until it was .025. I was going for .020, but realized the thickness was varying by about .002 around the circumference. If that was all, I would have kept sanding, because that much might squish out. But it's not perfectly round where it matters, on the ID, so doesn't didn't hug the head tightly. The original one fit so snugly, I had to walk it off, and I was afraid blowby would damage it with the looser fit. I'm going to fly Thursday morning, so I'll worry about it after that. If I can't do it with a soda can, I'll grab the sheet with the dimensions written on it and forward it to Ken.

Here's the old one next to my home made one:

I'd be more than happy to try and help you out. I have shims of various types that just may prove worthy. It just depends on how big it is. Ken

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXAHNP

Looks like you can get if you wanted. Making probably is better since $3 turns into more after shipping.

Phil