jon_focal_plane

Actually, I don't fly hard crashed receivers. When you think of how much time/money you have in these rascals, it's just not worth it. They just become bench equipment or go in a boat in the pool. If the crash wasn't that severe, I will usually replace the crystal and cycle them onto a slow testbed aircraft and subject them to the vibe/shock environments of flight for several hours before letting them go back into a higher performance ship. All that assumes successful engine off/on range checks. Pretty much the same story for servos as well.

Jonathan

Gidusko

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hey guys,

I have a 60lx on a weston magnum and it totally rips the sky apart, but i cant seem to keep a glow plug more than one or two flights. The plug usually deforms and is useless i have tried os-8, fox plugs, mc-9, various os plugs i had in my box. they all have the same fate of black and melted or blown out elements. The mc-9 actually starts to fall apart! the pin in the center seems to be getting blown out. I am using 15% omega and a APC 9-9 cut to 8-9 and static on a new os-8 is about 18500 to 19000 rpm. I set it by leaning to max rpm and then backing off about 500 rpm. It seems if i go richer it doesnt get on pipe. Do you all have any ideas for plugs that will not fail each flight cause i am at a loss. i love the engine and it has amazing power but it is damn expensive to put a new plug in after each flight. oh, i have run about 3/4 of a gallon or so.

daven

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I would raise the head by .003, go richer, or mess with other prop sizes.

Bob should chime in on the prop.

HighPlains

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Dave is correct that raising the head will help. But why are you leaning it out to peak each time? If you know the rpm it peaks at, start it richer and lean it to a figure below where you know peak is located. I used to know a guy that would lean his racing engine out to peak on the ground looking for every last rpm until he would burn a hole thru the piston top. Didn't take him too many engines before he figured it out. You may want to try an uncut prop too.

MJD

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Is it possible that the pipe is a hair on the short side for the prop you're using? If it is stubborn to get on the pipe unless the mixture is leaner than you seem to want to set it, it may be going on the lean side once it stages as it cannot satisfy fuel demand. If you lean it a bit and it goes on the pipe, does it fall off immediately when you richen back from that point? If you back off to where it seems to be falling off, can you stage it with a quick line pinch and does it stay there or try to?

Just curious, I could be off base. Paging Bob27!!!

MJD

bob27s

My Feedback: (19)

The prop and RPM are fine. No issue there. Maybe back off more like 600-700 - might help. You may want to try an APC 8.8x9.25 prop, and clip that to 8" diameter.

The engine should stage and stay on the pipe at any rpm over 17,500 (60LX with the SS muffler). The SS muffler also re-stages and re-peaks near 20,000 rpm but it looks like you are a bit short of that yet.

However....

If you are not using either a Tetra or Jett fuel tank, install one very soon, or you will toast the engine.

Blowing plugs comes from the engine going lean. Blowing insulators/posts out means its getting VERY hot. A head shim might help as dave noted, but lets evalue the fuel system first.

(if the head shim is the problem, fire up the engine with your 8x9, a new plug and full tank of fuel. Let it run full throttle for 1 minute, just short of peak rpm about 200-300. Shut it down. Check the plug. If its blown or distorted - shim the head up. If the plug is fine, the problem is most definately the engine going lean late in the flight - fuel system)

We wasted plugs for years in pylon. That last 1/3 of a tank, with a conventional tank, will guarantee you a blown plug - the clunk has no option but to suck some air as it bounce around. And at those rpms, it is bouning around a great deal. It only takes a few seconds of air bubbles to cause the engine to go over the edge. Our only option was to take off rich, and wait for it to go lean. With a bubble-jett or tetra tank, the engine simple never sees air bubbles, and holds the needle setting all the way to the last drop in the tank.

Let me know about you tank setup.
Bob

deckerv

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I have a Jett BSE FIRE 50 in my Whiplash.. pic is in my gallery and in Jett Engineering's hall of fame pics of delta planes

Gidusko

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Thanks alot guys i guess ill order a new tank today as to avoid frying my engine. ill also try one of the pylon props. i hope i can get this figured. ill let ya know what happens.

Crazy4Flight

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untill you get a new furl tank last third of your flight cut back on your throttle... at least 2/3 of flight is fast!

cncswiss1

you can always use the baby bottle liner trick, get the liner pinched in the stopper inside the tank, apply muffler pressure outside the bag, get fuel from inside.

Ramjet

OK, I have a Great Planes F-15 with a Jett 50 in front. Note the avatar... The Jett hauls it around very well. This plane was built by a local modeler that makes the most beautiful planes, but they are HEAVY. So is mine.
A Webra 40 would not / could not get it off the grass!!! The Jett 50 has no problem at all.

Ramjet

Strykaas

The Jett has 25% more power than a .40, based on displacement... The webra .50 would not compare to the jett but would perhaps allow you to get airborne
There are some videos around, showing a t-38 prop pusher with a webra .50. Worth a look.

Kmot

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I have two Jett's. Both in need of an airframe.

I bought a FIRE 120L because it was a Jett. I didn't know squat about Jett's but I figured bigger is better, lol. Well turns out it is for a scale warbird or something, not a speed plane.

I just got a Jett 40 Quickie from a cool RCU member and it is slated for an ARF Shrike.

bob27s

My Feedback: (19)

Jett 120 - Thunder Tiger's September Fury - 14x10 prop - turbo-jett muffler

(or if you want to try an experiment, one of supercool's AT-6 racing 16x8.5 props clipped down to around 15.25")

Kmot

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Thanks Bob. Actually, I posted the wrong pic. I have a rear exhaust.

Kmot

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Uh yeah, maybe it was the right picture. Like I said, I don't know squat about these yet. Anyway, here is Poppa Bear and Mama Bear!

bob27s

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ok, so we will have to work out something for a pipe tunnel

Methanolover

First, I must thank you Bob for your great work here!!

In my case , Angels' "The Rifle" isn't wide enough to accomodate my Jett 12 oz bubbelless tank. How about the hopper tank setup? does it help somewhat from going lean?

Henrik

Mods-R-Me

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Bob,

I looked on the Jett website for a 16-18oz tank, but the biggest they had was 12oz. What is the best alternative?

Mods

Rudeboy

Tettra bladder tanks... the pattern guys use 'em...

Check Performance Specialties.

HighPlains

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I have 18 oz tettra tanks for sale, about 15 left. To the US only, sorry.

bob27s

My Feedback: (19)

Id say go with an 8oz in the Rifle. You will get 5-7 minutes of flight time.

Also take a look at the various size Tetra tanks .... one of those might fit better.

Consider this.....

You can only effectively use 2/3 of the fuel in a conventional tank. With a 12 oz tank, that gives to 8 oz of usable fuel. You can safely draw about 9 oz from the tank without uncovering (at least partly) the clunk inlet, in at least a minimal flight attitude other than level.

With the bubble jett tank or tetra tank, you can use 100% of the fuel.
Also, you can litterally cram it in place - no foam padding needed (other than physical protection of the plastic tank)

A regular tank, combine with a hopper is an alternative, if it means you can properly foam pack both tanks... in that case, it would be a good alternative.

bob27s

My Feedback: (19)

Hey, if Highplanes has 18oz tetras left..... grab one !!

Central Hobbies stocks and sells other size Tetra bubble tanks.

Also, as a different alternative, we have in the past rigged up two bubble-jett tanks in parallel. Actually worked very well. Deflating and fueling sometimes is tricky, but not impossible once you get the technique down.

Methanolover

Thank you very much Bob !

Yes, 1/3 unusable is 8 out of 12. Should have thought of that.....why didn't I?

Also, I've been thinking about using 2 of 8oz bladder tanks. But I'll test hopper alternative first , see how it works.

VBR Henrik

Methanolover

[/quote]
Also, as a different alternative, we have in the past rigged up two bubble-jett tanks in parallel. Actually worked very well. Deflating and fueling sometimes is tricky, but not impossible once you get the technique down.
[/quote]

Could these two bubbless tanks be of different sizes, or do they need to be equal ?