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I blew an engine

Old 02-09-2008, 12:43 AM
  #26  
bigedmustafa
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Default RE: I blew an engine

The Thunder Tiger GP-61 is one of the best bargains out there! It'll be interesting to hear how long your next one lasts.
Old 02-09-2008, 12:59 AM
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Default RE: I blew an engine


ORIGINAL: XJet

My TT61GP was one of my favorite engines and has provided two years of kick-ass performance on a 40-sized trainer that has been clocked at over 175Kph (110 mph) on the straight and level.

Now I'm no sissy-boy, I fly hard-out so this engine was fitted with a tuned pipe and propped to pull around 15,500 on the ground, unloading to about 16,500 in the air -- maybe a little more in those full-power vertical dives ;-)

Everyone who saw this engine run and saw the plane it was in fly could not believe just how much power it put out and were amazed to discover that it was only a plain-bearing .61 that cost $85 brand new.

Unfortunately all good things must come to an end and today the engine stopped unexpectedly and left me to perform a perfect dead-stick landing, the roll-out stopping at my feet.

I went to refuel the plane and noticed the engine wasn't its usual self -- offering some resistance to turning.

On close inspection I saw the damage shown in the attached pictures.

Yep, I split that baby right down the middle!

It's worth noting that this engine has never been crashed and has only ever been in the one airframe. The props were always well balanced and it was run on a diet of 5% nitro and 20% oil (the same hi-castor blend of oil Morgans uses in its Omega fuel).

I guess the TT61GP just isn't built to take this kind of punishment but I figure that I sure got my $85 worth of fun out of it. In fact, I'm going to buy another!

------------


If that is all of the damage that there is, why not replace the crankcase?


Ed Cregger
Old 02-09-2008, 03:47 AM
  #28  
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Default RE: I blew an engine


ORIGINAL: Ed Cregger
If that is all of the damage that there is, why not replace the crankcase?
Getting TT spare parts around here is not easy.

I even tried to get some prices from ThunderTiger4U but they ignored my requests -- but I know that RadicalRC will ship me a new one and it'll be here within the week.

It also means I'll be able to use the old engine for spares -- hell, it still had plenty of pinch left before it blew.

And TT parts (when you can find someone willing to sell them) are often priced like gold anyway.

Old 02-09-2008, 06:23 AM
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Default RE: I blew an engine

Not sure why you were waiting for an e-mail from www.thundertiger4u.com, the crankcase for the GP-61 is right on their website. Search for PN0065 and you'll get a price of $25.21.

The folks at www.infinitehobbies.com list the same part for $27.39.

Even www.eHobbies.com showed the GP-61 crank case as available for $27.29.

Lots of good Thunder Tiger resellers out there with pricing available simply by punching the part number in and clicking on "search." Why does everyone say Thunder Tiger parts are so hard to come by?

Edit: I thought $25.21 for a .60-size crank case seemed pretty reasonable, so I pulled up some comparable engine parts for fun:

$49.99 Natural crankcase for O.S. Max .65 LA
$40.99 crankcase for Super Tigre G-61/G-61 ABC
$29.99 crankcase for Tower Hobbies .61
$49.00 crankcase for Magnum XLS .61A
$18.95 cranksase for Evolution .61 NT (wow!)

Apparently Thunder Tiger parts are not only readily available, but they're cheaper than most of the other major brands.
Old 02-09-2008, 06:32 AM
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Default RE: I blew an engine

One of our guru members at the club had a TT 4 stroke do similar. He had crashed it previously but it passed a thorough examination and clean before being fitted to a new plane. A couple of flights later, while running the engine on the ground it blew apart with a similar centreline crack as you show. Luckily, no injuries to anyone or the plane. All we could put it down to was a hidden crack, caused by the previous crash.
Old 02-09-2008, 12:53 PM
  #31  
XJet
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Default RE: I blew an engine

ORIGINAL: bigedmustafa

Not sure why you were waiting for an e-mail from www.thundertiger4u.com, the crankcase for the GP-61 is right on their website. Search for PN0065 and you'll get a price of $25.21.
I was waiting for an email because I needed to know the total amount -- including shipping to New Zealand. I guess they're not interested in shipping outside the USA.

Why does everyone say Thunder Tiger parts are so hard to come by?
I don't know about the USA but I live in NZ where there is just one importer and their range of spares is very low -- quite the opposite of their prices which are very high.

Old 02-10-2008, 05:04 AM
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Default RE: I blew an engine

Sorry, XJet, I wasn't really talking about your comments in particular. I have no idea what your shopping circumstances must be like in New Zealand. You're a Thunder Tiger engine owner, and not one of the folks who critisizes them out-of-hand without ever having owned one.

Thunder Tiger engines get bashed here in the states by folks for hard-to-find parts when it simply isn't the case here.

Hopefully you will track down your crank case quickly enough if you don't replace the whole engine outright.
Old 02-10-2008, 05:37 AM
  #33  
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Default RE: I blew an engine

Bruce,


This failure might actually be metal fatigue related, after... if I calculate 100 hour x 60 minutes x 10,000 RPM average...

This engine must have undergone ~60,000,000 stress cycles... If any metallurgist would care to chime-in and remark, that would be nice.

Unlike steel, which reduces in strength and eventually loses about 30% of its original strength, at ~6,000,000 stress cycles, after which weakening is virtually stopped; aluminium will continue to weaken until it would disintegrate...
Old 02-10-2008, 09:13 AM
  #34  
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Default RE: I blew an engine

LOOKS like the bearing went then it split. is my guess, thats right there's no bearing.

there is a bronze sleeve there
Old 02-10-2008, 11:36 AM
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Default RE: I blew an engine

Probably a pre existing casting fault. A tool mark or something aggrevated the fault and it grew to ultimate failure. There are by its nature stresses place on the crankcase casting. You just had a bad one. To bad it is not under warranty.

Cheers,

Chip

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