Author Topic: Thunder Tiger Pro .25, do I need a hotter glow plug?(solved) (Read 2554 times)

RknRusty · « **on:** July 22, 2013, 09:53:37 PM »

On the Shoestring that I sport fly(my first larger than 1/2A plane), I'm using a Thunder Tiger Pro .25 with a ST venturi and needle valve. With a 9x5 Master Airscrew prop, once I get it needled to run at 11,600 rpms for launch, it consistently gives me 5.2 second laps on 58' lines and a dependable Rich Lean Rich break between level laps and stunts. I can't really call it a 4-2-4, because it isn't even close to the clean 4 stroke you hear on others like a Fox, but it's still getting the job done very well. My run times are always 5:13 on 3 ounces of Sig 15/20, and I always get a nice lean warning one lap before it shuts off.

My problem is, before every flight, I have to re-adjust the needle. It really hates getting over rich, and to get it to recover, I have to pinch the line to lean it out and go back to adjusting. It must get the plug wet when I'm cranking it. I always manage to get it right, because my run times and lap times don't vary. But I waste up to a full minute fiddling and walking out to the handle. I'm using an OS #8 medium heat plug, and was wondering if maybe a hotter plug would make it more cooperative. Does my diagnosis sound sensible, and if so, what would be a good hotter plug to try? Is my current OS#8 medium and an OS#7 medium-hot plug interchangeable? Or even a hot OS#6.

If you want to hear my engine run, here's a video of a couple of flights. Yes, they're ugly, but I'm just getting started.

(It's a lot less jerky if you click the Youtube logo in the bottom right of the video window)

Thanks,
Rusty

Air Ministry . · « **Reply #1 on:** July 23, 2013, 02:03:55 AM »

Id run 10 gallons through one , hauling 47 Oz Plane .
Ran a Tornado 10 x 6 worn down to 9 1/2 on the concrete ,
with the L.E.s rounded on the grass .
If it got really windy I threw the 9 x 6 on .

Used it in a combat wing with the big prop to get slow for the 3.5 limit .4 strokeing .

I definately used a Glow Plug in it.

probly a S T , Enya 3 , or whatever else was closest to hand .

The Big Seret was the Fox 25 schneurle intake whittled down to fit the hole & the rattly old Taipan spray bar .
Sometimes I sealed it with a bit of fuel tube , but normally the needle was a loose fit & bled Air ,
so if adjusting , youre fingers touch leaned it , and it took a few seconds finger off to settle again .

This gave it a nice burble , & the spraybar being on the outer face of the tank , the speed increased with the hight.
So you could set max. lean in O/H 8s ( as in good power there ) and itd drop off rich @ half circle hight ,
but cut in vertical inloops , or in the Square Turns .

So Fluked it perfectly with what was to hand . Only ever ran 5 % or 10 % whatever was going juice .
Still runs good , but some people have trouble starting it when I used it in Bendix with a 7x8 Tornado ,
Supriseingly it kept up , near enough . AND Id thought Id wrecked it the first time I ran it ,
in a plane ( Goldberg Shoestring ) Leanish in the 40 degree heat , last centurie .

So , theyre not a bad Injun. The intake gave 15.2 Sq mm . maybe underproped ? if it wont chunter round rich.
I usually used 55ft of .018 stranded wire . So it steered in hurricanes without stretching them .

It stuggled with the full 10 x 6 , till I tried a touch & go in a bit of a gale on the concrette resivior .immediate improvement evident .

will throw this picture on , as it shows the Tornados a bit meatier , AND thats the 9 x 6 . & theres the Top Flites , which are good ' vertical . So dont sneeze at Either

Thats an absconded pic of a backward prop . Ive got White Ones ( & a few Black , R & L H . ) and a pair of GP 25s with the Old ST 35 S intakes , which seem better than my ancient one , on them .

Akihiro Danjo · « **Reply #2 on:** July 23, 2013, 02:05:57 AM »

Have you tried a new plug?

RknRusty · « **Reply #3 on:** July 23, 2013, 04:54:38 AM »

Quote from: Akihiro Danjo on July 23, 2013, 02:05:57 AM

Have you tried a new plug?

Akihiro, the one in it now is new. It's clean, shiny and glows brightly. I bought two OS#8s and put one in it when I got the engine, fairly new but already run in. I haven't tried the other new plug in it, but I've run 2-1/2 quarts of fuel since I've had it.

Matt, I'm still working on my coffee, so give me a while to digest your response, and I'll get back to you on that.
Thanks,
Rusty

Brett Buck · « **Reply #4 on:** July 23, 2013, 07:13:38 AM »

Quote from: RknRusty on July 23, 2013, 04:54:38 AM

Akihiro, the one in it now is new. It's clean, shiny and glows brightly. I bought two OS#8s and put one in it when I got the engine, fairly new but already run in. I haven't tried the other new plug in it, but I've run 2-1/2 quarts of fuel since I've had it.

Matt, I'm still working on my coffee, so give me a while to digest your response, and I'll get back to you on that.
Thanks,
Rusty

Just an observation, you are running it FAR richer and slower in flight than I would have expected possible. I am very surprised that it will remain at that speed reliably. It may be that you are running it so rich that it won't reliably start at that setting. That, and/or some interesting tuning effect in the muffler.

I am not telling you to change anything since it seems to be mostly working now, but I would be sorely tempted to put on a 10-3 APC and crank it up to normal operating RPM and in a solid 2-stroke in level flight.

Brett

RknRusty · « **Reply #5 on:** July 23, 2013, 08:09:46 AM »

Quote from: Brett Buck on July 23, 2013, 07:13:38 AM

Just an observation, you are running it FAR richer and slower in flight than I would have expected possible. I am very surprised that it will remain at that speed reliably. It may be that you are running it so rich that it won't reliably start at that setting. That, and/or some interesting tuning effect in the muffler.

I am not telling you to change anything since it seems to be mostly working now, but I would be sorely tempted to put on a 10-3 APC and crank it up to normal operating RPM and in a solid 2-stroke in level flight.

Brett

Maybe I should, Brett. I'm pretty sue this engine was never meant to run the way I'm forcing it to, but when I hit on the current configuration I went with it. I started out knowing nothing about what I was doing with this type of model, and am really enjoying learning about it. It's such a good flier, always tight on the lines and turns faster than I expected. I already have a 10x4 APC and a 10x4 TopFlite woody, so next time out I'll try those and launch it at the edge of lean before I buy a 10x3. Also before I switch props, I will try cranking it lean and riching it down to my launch rpm, which might keep it dry enough to tune it more quickly. I bet with a 10" prop I'll get some longer runs too.

I sure am gonna have a lot of props in my box before it's all over.

Thanks,
Rusty

Brett Buck · « **Reply #6 on:** July 23, 2013, 10:49:38 AM »

Quote from: RknRusty on July 23, 2013, 08:09:46 AM

Also before I switch props, I will try cranking it lean and riching it down to my launch rpm, which might keep it dry enough to tune it more quickly. I bet with a 10" prop I'll get some longer runs too.

Much much longer. If you just want to lean it out temporarily, don't fiddle with the needle, just put your finger over the fuel tank vent until it speeds up, then let go. Standard operating procedure to get the engine to the proper operating temperature before needling.

Quote

I sure am gonna have a lot of props in my box before it's all over.

You ought to see my prop collection, although it pales in comparison to Ted's. As you to through different engines, you tend to collect a wide variety of props. Not to mention random things in your toolbox.

Brett

RknRusty · « **Reply #7 on:** July 23, 2013, 11:21:40 AM »

Quote from: Brett Buck on July 23, 2013, 10:49:38 AM

...If you just want to lean it out temporarily, don't fiddle with the needle, just put your finger over the fuel tank vent until it speeds up, then let go. Standard operating procedure to get the engine to the proper operating temperature before needling....

Brett

Ah, see, I learned another tidbit today, even if it should have been a no-brainer for me. I'm an old pressure bladder guy learning to use hard tanks. When I get it all sorted out and can concentrate on precision stunts, I'll show y'all a good video of my exploits. I fly at Fort Jackson, so occasionally you can hear mortars and machine gun fire in the background, good for exciting emphasis.

Reptoid · « **Reply #8 on:** July 24, 2013, 02:19:13 PM »

Rusty;
In your flight video your engine is leaning out (breaking) alot more in outsides and inverted flight. This generally indicates that your tank is too high. This can cause flooding or rich running on start-up with some engine tank combos. Try moving the fuel tank lower 1/16" at a time until you get even break/speed on inside/outside loops. This will make it easier to get consistent manuevers and will likely help your "rich at start-up" issue.

Brett Buck · « **Reply #9 on:** July 24, 2013, 06:25:44 PM »

Quote from: Reptoid on July 24, 2013, 02:19:13 PM

Rusty;
In your flight video your engine is leaning out (breaking) alot more in outsides and inverted flight. This generally indicates that your tank is too high. This can cause flooding or rich running on start-up with some engine tank combos. Try moving the fuel tank lower 1/16" at a time until you get even break/speed on inside/outside loops. This will make it easier to get consistent manuevers and will likely help your "rich at start-up" issue.

It *might* mean that the tank is misplaced. What frequently happens if you run it too slowly is that it will tend to run differently in one direction turn than the other. This was one of the serious flaws with most schneurle engines, more usually with upright and inverted, but sometimes on profiles, too. This is what made Ted Fancher (and I, by extension) stick with ST46s until piped engines came along. It's still a problem with some piped engines, and a lot of the work we have done since they became available was to try to reduce or eliminate the effect.

if it is the same speed upright and inverted but different in the maneuvers, try to shim the tank. Sometimes one G is not enough to make tank shims evident. If you can't get it the same on positive and negative G maneuvers, AND level flight, the problem is almost certainly not the tank, it's something internal to the engine or engine setup. In this case I expect that it is exacerbated by low in-flight revs/running a 1 hp engine at .3 hp.

Brett

RknRusty · « **Reply #10 on:** July 24, 2013, 07:12:16 PM »

My tank is adjustable up and down, so I can tinker with that. I have the rear shimmed out a couple of degrees farther than the front since the plane yaws out slightly, thinking that helps keep the pickup and feed line parallel to the circle. I might be over thinking again. Right now, the edge of the wedge sits about 3/16" higher than the venturi center.

Brett, I think you had the best advice. I'm making this engine do something it was never designed to do, and run a rich-lean break. Tomorrow morning, barring rain and weeds on the field, I'm going to try my two 10x4 props and let the engine run in its happy rpm range. I don't have a 10x3 like you suggested, but maybe I'll get an idea of how it runs that way. I've heard APCs are under pitched, so if that's true, it might like that one best.

I'm also going to go back to uniflow. I don't think I've mentioned it on this forum, but my first tank was passing a steady stream of bubbles(not foam) from the uni vent right into the feed line, so I went normally vented. Mr. Brodak was nice enough to replace it, and I test ran the new tank with no sign of bubbles. So After the first test flight with the 10" prop, I'll switch over to uniflow and see if it makes any difference. I don't know what to expect from uniflow. I hope it still gives me a warning burp when it's about to suck air. I haven't gotten the hang of knowing my run times yet, as you might have witnessed if you saw the end of that video I made Sunday. But tomorrow, I promise myself that I'm going to use all of the air and not try to compact my stunts. Those old sport 1/2A habits are hard to break. And the plane... is easy to break. I've been lucky so far.

Thanks everyone for your interest in my training adventures.
Rusty

Steve Helmick · « **Reply #11 on:** July 29, 2013, 09:58:45 PM »

"I've heard APCs are under pitched, so if that's true, it might like that one best."

No, that's bad info. The APCs act like they have a little more pitch than the rating. Master Airscrew products are well below the rated pitch. I doubt that it'll go fast enough (for the Shoe) with the APC 10-3, but it's still something I'd try.

I suggest you get the tank working on Uniflow and muffler pressure piped into the Uniflow inlet.

Steve

RknRusty · « **Reply #12 on:** July 29, 2013, 10:10:54 PM »

Quote from: Steve Helmick on July 29, 2013, 09:58:45 PM

"I've heard APCs are under pitched, so if that's true, it might like that one best."

No, that's bad info. The APCs act like they have a little more pitch than the rating. Master Airscrew products are well below the rated pitch. I doubt that it'll go fast enough (for the Shoe) with the APC 10-3, but it's still something I'd try.

I suggest you get the tank working on Uniflow and muffler pressure piped into the Uniflow inlet. Steve

I keep coming back to the MA 9x5 every time, so I'll fly it tomorrow. It gets the right lap times and plenty of go in the maneuvers. One problem, though. I ordered a couple of spare MA 9x5s and the new ones are 1/8" narrower than my old one.

After I balanced it and put it on the plane it looked different so I measured it. That'll probably throw a kink in the works, I'm really irritated with it. I'll try it, but I might end up with the old fat one back on it. It's had more punishment than I'm comfortable with though. It's still balanced, but scuffed up. No nicks and I polished the edges with some 600 grit paper. The new one is not even one of the ones advertised as "Now narrower for higher RPM." Jeez, new and improved always sucks. First New Coke, now new improved props.

Rusty

RknRusty · « **Reply #13 on:** July 29, 2013, 10:13:24 PM »

Also, regarding the title of this thread; no, my glow plug is just fine now that I've gotten the hang of cranking the engine.

Timothy Payne · « **Reply #14 on:** August 10, 2013, 10:00:01 AM »

Just seen your Utube clip of your fox 35. - The fox engine you should look out for (if you can find a decent one) is the fox 36X. They're basically a tuned 35, although I can highly recommend them - I'm in the process of building 46" combat which will progress to a 36X after I've got used to it with a McCoy 29 Redhead (another goodun').

Tim

RknRusty · « **Reply #15 on:** August 10, 2013, 12:37:44 PM »

Quote from: Timothy Payne on August 10, 2013, 10:00:01 AM

Just seen your Utube clip of your fox 35. - The fox engine you should look out for (if you can find a decent one) is the fox 36X. They're basically a tuned 35, although I can highly recommend them - I'm in the process of building 46" combat which will progress to a 36X after I've got used to it with a McCoy 29 Redhead (another goodun').

Tim

Ah, good, I'm glad my videos are getting some play time, though I did fumble about getting that one to run. It was my first time cranking a Fox. It has some serious compression. I usually crank my Thunder Tiger with bare fingers, but this Fox is a real bone breaker. Leather gloves are definitely in order. Okay 36X, I'll commit that to memory for future reference. Thanks, Timothy.
Rusty

Brett Buck · « **Reply #16 on:** August 10, 2013, 12:39:02 PM »

Quote from: Timothy Payne on August 10, 2013, 10:00:01 AM

Just seen your Utube clip of your fox 35. - The fox engine you should look out for (if you can find a decent one) is the fox 36X. They're basically a tuned 35, although I can highly recommend them - I'm in the process of building 46" combat which will progress to a 36X after I've got used to it with a McCoy 29 Redhead (another goodun').

Tim

Be advised that the 36x is not a good stunt engine, it's a very hot combat engine.

Brett

RknRusty · « **Reply #17 on:** August 11, 2013, 09:41:13 PM »

Quote from: Brett Buck on July 23, 2013, 07:13:38 AM

...... I am not telling you to change anything since it seems to be mostly working now, but I would be sorely tempted to put on a 10-3 APC and crank it up to normal operating RPM and in a solid 2-stroke in level flight...

Brett, it took me a while, but I finally got an APC 10x3, as you suggested. It's mounted up and ready to fly and I'm itching to get out there and try it. Last week I quit trying to make it 4-2 and ran the T.Tiger in its 2 stroke sweet spot and it ran very well, though faster than I like. At the time I only had a pair of TF wood 10x4 props, a wide one(must have been an older one) and a narrow one. My laps were pretty quick for me on 58' lines(4.8 sec) and my stunts were ugly, though I did get all of them attempted. When I try out the APC 10x3, I'll take two sets of lines, my 58' and my 61' set. Unfortunately the HS only had one 10x3. I also have a narrow MA 9x4 that I might try, just because I haven't yet.

Something else that made the engine much happier is I inverted the spraybar so I eliminated more than 3" of fuel line, now going straight out of the tank over the top and plugging into the engine, rather than over, under and back up. It's been a first flip starter since I did that. And my new uniflow tank that Brodak was nice enough to replace makes a world of difference. No more wasting fuel after leaning out for 10 extra laps. No more bubbles crossing over from the uni pipe into the pickup. That's why I had been running normally vented in my past flights.

I'll post back in my flying thread with the results of the 10x3. My helper is out of town, but I might stooge a couple of flights this week.
Rusty

Brett Buck · « **Reply #18 on:** August 12, 2013, 12:48:59 AM »

Quote from: RknRusty on August 11, 2013, 09:41:13 PM

Brett, it took me a while, but I finally got an APC 10x3, as you suggested. It's mounted up and ready to fly and I'm itching to get out there and try it. Last week I quit trying to make it 4-2 and ran the T.Tiger in its 2 stroke sweet spot and it ran very well, though faster than I like. At the time I only had a pair of TF wood 10x4 props, a wide one(must have been an older one) and a narrow one. My laps were pretty quick for me on 58' lines(4.8 sec) and my stunts were ugly, though I did get all of them attempted. When I try out the APC 10x3, I'll take two sets of lines, my 58' and my 61' set. Unfortunately the HS only had one 10x3. I also have a narrow MA 9x4 that I might try, just because I haven't yet.

Something else that made the engine much happier is I inverted the spraybar so I eliminated more than 3" of fuel line, now going straight out of the tank over the top and plugging into the engine, rather than over, under and back up. It's been a first flip starter since I did that. And my new uniflow tank that Brodak was nice enough to replace makes a world of difference. No more wasting fuel after leaning out for 10 extra laps. No more bubbles crossing over from the uni pipe into the pickup. That's why I had been running normally vented in my past flights.

I'll post back in my flying thread with the results of the 10x3. My helper is out of town, but I might stooge a couple of flights this week.
Rusty

Just going from a 10-4 Top Flite to a 10-4 APC would have a tremendous effect. The APC has far, far less parasitic drag. I tried every kind of 9-4 and 10-4 there was in the earlier experiments and just changing the brand with otherwise the same parameters was extremely dramatic. The 9-4 APC was like magic on the 20FP, it was not as magical on other engines, but that's usually what I ended up with.

You just have to get an assortment and try them, and then do a fair test of them. I can make somewhat reasonable guesses what I need from what we can call "extensive experience" (being an old fart that has done this forever) but I am still occasionally surprised.

Of course, while you are doing you lengthy and extensive experiments, you are also getting flight time, so it's not wasted.

Brett

Author Topic: Thunder Tiger Pro .25, do I need a hotter glow plug?(solved) (Read 2554 times)

RknRusty

Thunder Tiger Pro .25, do I need a hotter glow plug?(solved)

Air Ministry .

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

Akihiro Danjo

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

RknRusty

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

Brett Buck

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

RknRusty

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

Brett Buck

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

RknRusty

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

Reptoid

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

Brett Buck

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

RknRusty

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

Steve Helmick

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

RknRusty

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

RknRusty

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?

Timothy Payne

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?(solved)

RknRusty

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?(solved)

Brett Buck

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?(solved)

RknRusty

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?(solved)

Brett Buck

Re: Thunder Tiger Pro .25, do I need a hotter glow plug?(solved)