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Author Topic: ETA .29 help  (Read 1433 times)

Offline Oldenginerod

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ETA .29 help
« on: November 15, 2020, 11:27:09 PM »
ETA .29 with a Merco muffler.  Also looks like it has an Enya NVA.  Clearly had quite a bit of early McCoy influence.

I'd like to attach pictures, but can't figure out how.  Sorry, this has happened to me before. b1

Had it given to me by a mate yesterday.  He wasn't sure where it came from, but believed his Father in Law may have retrieved it from a lake where a local RC club fly.  That doesn't really add up because it's a CL/FF engine.  Maybe someone had an old-time free flighter?  They were apparently popular for Team Race and Free Flight and from all reports were a very strong performing engine.  In fact, one report I read (Think it was Modelenginenews) said that they were timed for performance so much that they would run rough and spray fuel out of the inlet until you propped the engine to find the "sweet spot".  Also, I believe that the needle valve ran in a 2 piece spray bar, spanning the venturi in the open air.  I guess that means that the one piece Enya unit may be a little restrictive.

I had no real trouble dismantling it, but have opted to leave the piston in the cylinder to preserve the two (yes, two) piston rings.  Also, the crank bearings are locked solid, so they will require a good soaking.  Not keen on the A/Freeze boil due to the black anodised prop driver and head.  It's far from pristine, so will just get a tidy-up and test run.
« Last Edit: November 16, 2020, 12:40:41 AM by Oldenginerod »


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Offline qaz049

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Re: ETA .29 help
« Reply #1 on: November 16, 2020, 12:41:03 AM »
ETA .29 with a Merco muffler.  Also looks like it has an Enya NVA.  Clearly had quite a bit of early McCoy influence.

I'd like to attach pictures, but can't figure out how.  Sorry, this has hgappened to me before. b1

Had it given to me by a mate yesterday.  He wasn't sure where it came from, but believed his Father in Law may have retrieved it from a lake where a local RC club fly.  That doesn't really add up because it's a CL/FF engine.  Maybe someone had an old-time free flighter?  They were apparently popular for Team Race and Free Flight and from all reports were a very strong performing engine.  In fact, one report I read (Think it was Modelenginenews) said that they were timed for performance so much that they would run rough and spray fuel out of the inlet until you propped the engine to find the "sweet spot".  Also, I believe that the needle valve ran in a 2 piece spray bar, spanning the venturi in the open air.  I guess that means that the one piece Enya unit may be a little restrictive.

I had no real trouble dismantling it, but have opted to leave the piston in the cylinder to preserve the two (yes, two) piston rings.  Also, the crank bearings are locked solid, so they will require a good soaking.  Not keen on the A/Freeze boil due to the black anodised prop driver and head.  It's far from pristine, so will just get a tidy-up and test run.

The big question is which version is it? Quite a few different versions. I run mine with a slightly clipped APC 8x7" prop in a B Class team racer. They run fine with a 4mm dia NVA less speed more range. Replacement two piece NVA's are available on ebay as are rings. From memory the races are R-4 and R-6 the same as an Oliver Tiger diesel and a bunch of other British engines from the era.  I've seen one pull a sports stunter around quite well on a 9x6" prop. Should be ok with the Enya NVA. Some of the vintage British stunters used ETA .29 during the 1950's. The standard hole with the 2-piece NVA is too big for stunt.

Offline Oldenginerod

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Re: ETA .29 help
« Reply #2 on: November 16, 2020, 01:33:16 AM »
Thanks qaz049.  I've done a little more research (Modelenginenews) and deduced that it's a Mark 6 (Serial # starting with "0"), November 1964, so pretty late in the production run.  I hope to get the bearings freed up and should be able to give it a try with a couple of case gaskets to be made.  The 6BA prop nut may be a problem.  It has the original conical prop nut with flats either side, but it's rather butchered.

I'm still looking for a tutorial on inserting pictures.  Any help would be appreciated.

Rod.

Offline qaz049

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Re: ETA .29 help
« Reply #3 on: November 16, 2020, 02:11:09 AM »
Thanks qaz049.  I've done a little more research (Modelenginenews) and deduced that it's a Mark 6 (Serial # starting with "0"), November 1964, so pretty late in the production run.  I hope to get the bearings freed up and should be able to give it a try with a couple of case gaskets to be made.  The 6BA prop nut may be a problem.  It has the original conical prop nut with flats either side, but it's rather butchered.

I'm still looking for a tutorial on inserting pictures.  Any help would be appreciated.

Rod.

An ETA 6C will have threaded holes in the exhaust. Might be one of those. I believe that hundreds (a pallet full) were "dumped" in Oz and sold by Ivor F when ETA decided that it wasn't profitable to make engines any more and the Super Tigre .29's were blowing them away in competition, were cheaper, and held together. From memory the prop "sleeve nut" should be 1/4" x 26tpi BSF like an Oliver Tiger as well. The screws in one of mine were 6 BA x 1/2" long. I bought a packet of socket headed versions  off Ebay. Should be available from any Model Engineering supplier.

Offline Oldenginerod

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Re: ETA .29 help
« Reply #4 on: November 16, 2020, 02:49:57 AM »
Thanks again.  I'll check tomorrow but I don't recall exhaust mounting holes- Maybe a MK6 rather than a 6C.
I also have a pack of 6BA cap screws on the way from a local supplier.  I would normally opt for original style, but as this engine is already a little knocked around I will focus on function rather than form.

Offline qaz049

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Re: ETA .29 help
« Reply #5 on: November 16, 2020, 03:04:16 AM »
Here's some pics of one of my 6c's bench running slow and very rich. The other is a Czech ETA .29 mk4 replica mounted on an engine plate (unfinished) almost ready to go into a B Class Teamracer. These had a proper NVA (not two Piece). Not as strong a runner as the 6c. The latter turned an APC 8" x 7" prop at +17K on 10% Nitro fuel.

The secret to posting pictures seems to be to reduce the size of the file to around 1200x 900 or so pixels before uploading. The combined size of the attached files needs to be less than 1000K bytes.

Offline qaz049

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Re: ETA .29 help
« Reply #6 on: November 16, 2020, 03:06:54 AM »
Thanks again.  I'll check tomorrow but I don't recall exhaust mounting holes- Maybe a MK6 rather than a 6C.
I also have a pack of 6BA cap screws on the way from a local supplier.  I would normally opt for original style, but as this engine is already a little knocked around I will focus on function rather than form.

I see what you mean about the prop nut. Can you make one or get someone to make one? I don't think I have any spares. I don't use a muffler, but they are ear-shatteringly noisy  :)

Offline Brian Hampton

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Re: ETA .29 help
« Reply #7 on: November 16, 2020, 07:07:43 PM »
Ah...memories. Back in about '58 when I was 15 my very first engine was a second hand ETA 29 which needed new rings which I got from my LHS and fitted myself to the great surprise of the guy who gave me the engine :). He also showed me and two of my school friends how to build a solid wing trainer so we could learn to fly. So there was me with an ETA 29, one with a McCoy 29 RR and one with a Dooling 29!!

About 5 years ago I picked up another ETA 29 off the 'bay just for memory's sake which needed some tidying up. A stripped screw hole and a new cylinder head then onto the test stand for a quick, but quite rich and noisy, run. This one is a Series 4, serial #42985.

Offline Air Ministry .

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Re: ETA .29 help
« Reply #8 on: November 16, 2020, 10:44:27 PM »
Theres a lot of info out there , if you search for it. Barton Forum is into classic british stuff . ' B ' team race . info here here . https://stunthanger.com/smf/rat-racing-and-team-racing/classic-b-team-plans/  S?P



Really should go in something like this ,



https://www.hippocketaeronautics.com/hpa_plans/categories.php?cat_id=29&sessionid=5a2ea021d277194d1f6018abf8dd097f&page=2

good for 115 mph on 20 % nitro , in a aerodynamically c lean machine .


Offline Oldenginerod

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Re: ETA .29 help
« Reply #9 on: November 17, 2020, 12:15:54 AM »
Ah...memories. Back in about '58 when I was 15 my very first engine was a second hand ETA 29 which needed new rings which I got from my LHS and fitted myself to the great surprise of the guy who gave me the engine :). He also showed me and two of my school friends how to build a solid wing trainer so we could learn to fly. So there was me with an ETA 29, one with a McCoy 29 RR and one with a Dooling 29!!

About 5 years ago I picked up another ETA 29 off the 'bay just for memory's sake which needed some tidying up. A stripped screw hole and a new cylinder head then onto the test stand for a quick, but quite rich and noisy, run. This one is a Series 4, serial #42985.

My engine has serial #0361164, according to Modelenginenews makes it a Mk6 (0), 36th engine built in the 11th month 1964.  There is some conjecture about the dating system- nothing is confirmed but the method is "strongly supported".

I soaked the front housing in fuel today and after a little persuasion the bearings freed up fine.  Gave it a good lube and they feel fine, so I won't be removing them prior to a test run.

Offline qaz049

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Re: ETA .29 help
« Reply #10 on: November 17, 2020, 04:48:13 AM »
My engine has serial #0361164, according to Modelenginenews makes it a Mk6 (0), 36th engine built in the 11th month 1964.  There is some conjecture about the dating system- nothing is confirmed but the method is "strongly supported".

I soaked the front housing in fuel today and after a little persuasion the bearings freed up fine.  Gave it a good lube and they feel fine, so I won't be removing them prior to a test run.

Probably a good idea to leave the bearing. I put some high quality BB's in one of mine, got them off SMR. David Owen kindly put them into the front housing using a jig he either got from Ken Bedford or made to his specs. Apparently it correctly aligned the bearings and the crank and this was critical. Wonder what happened to it?

I didn't know that Ken Bedford was a New Zealander either. Interesting story here.

http://aerosports.net.au/LS/Model_Aircraft_Stuff/B_TEAMRACE_WARS_1953.html

Offline rustler

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Re: ETA .29 help
« Reply #11 on: November 19, 2020, 08:29:03 AM »
Remember Gus Johnson who came over to Britain and won 29 class speed at our Nats with an ETA 29.
Ian Russell.
[I can remember the schedule o.k., the problem is remembering what was the last manoeuvre I just flew!].

Online Robert Zambelli

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Re: ETA .29 help
« Reply #12 on: November 21, 2020, 06:32:47 AM »
I wish I could help but Iíve never had to disassemble my ETA engines.
I will state, however, that in my opinion, they are some of the finest engines to ever come out of Great Britain.
I purchased the two shown at a swap meet in NJ around twenty years ago, both brand new for
$25 each.
I installed the glow engine in my Icarus Jr as it was shown on the plans. The combination was perfect. I installed an ENYA NVA and used a Top Flite 10-6 prop. Running on Brodak 10/23 50-50 fuel, itís a perfect OTS plane. The photo shows the muffler that came with the engine Ė I assume itís the factory unit. Due to the design of the muffler, it quiets the engine but also increases the power. There is a slight gain in RPM and the plane performs much better. The only modification I made was the ENYA NVA.
The other engine, (S/N 50269) is still brand new and was skillfully converted to spark ignition.
I hope you enjoy your ETA as much as I do mine.
Bob Z.

Offline Oldenginerod

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Re: ETA .29 help
« Reply #13 on: November 21, 2020, 05:06:01 PM »
Thanks Robert.  It's interesting to hear that your engine had an Enya NVA installed, as mine has.  It was commented to me that the Enya NVA would severely restrict power and that the MERCO muffler would destroy the internals of the engine.  I really don't see that the muffler would be detrimental apart from maybe running a little hotter.  Then again, the Enya NVA would be increasing fuel draw (good for stunt) which would in turn richen the mixture and keep things cooler.  Well, that's my theory.   H^^

Offline qaz049

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Re: ETA .29 help
« Reply #14 on: November 21, 2020, 10:39:17 PM »
Thanks Robert.  It's interesting to hear that your engine had an Enya NVA installed, as mine has.  It was commented to me that the Enya NVA would severely restrict power and that the MERCO muffler would destroy the internals of the engine.  I really don't see that the muffler would be detrimental apart from maybe running a little hotter.  Then again, the Enya NVA would be increasing fuel draw (good for stunt) which would in turn richen the mixture and keep things cooler.  Well, that's my theory.   H^^

Your informant may be talking about the muffler strap distorting the crankcase. Just don't tighten it too much. 

Online Robert Zambelli

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Re: ETA .29 help
« Reply #15 on: November 22, 2020, 10:47:00 AM »
Thanks Robert.  It's interesting to hear that your engine had an Enya NVA installed, as mine has.  It was commented to me that the Enya NVA would severely restrict power and that the MERCO muffler would destroy the internals of the engine.  I really don't see that the muffler would be detrimental apart from maybe running a little hotter.  Then again, the Enya NVA would be increasing fuel draw (good for stunt) which would in turn richen the mixture and keep things cooler.  Well, that's my theory.   H^^

Hello, OER!
Actually, I installed the ENYA NVA. The engine was originally equipped with a speed type NVA, with no spray bar. Designed for pressure only, it will not draw fuel. The ENYA NVA is the perfect size and provides great fuel draw. My engine has two tapped holes for the muffler which, I believe, is factory original.

The muffler is a true extractor - if you're interested, I can post a sketch of the innards and you'll see how it functions.

Bob Z.

Offline qaz049

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Re: ETA .29 help
« Reply #16 on: November 22, 2020, 03:46:33 PM »
Only the last model ETA .29 had the tapped muffler holes in the exhaust. It was the 6c. They will run on suction with the big venturi hole. But only as a racing engine.

Offline Oldenginerod

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Re: ETA .29 help
« Reply #17 on: November 22, 2020, 03:48:42 PM »
Thanks Robert, it's nice to know the Enya NVA is a positive addition.  I'm not fussed about the muffler.  I have no plans for an airframe to suit the engine, so it will only be bench run.  The MERCO muffler will do for that.  My engine doesn't have tapped muffler mount holes.  The MERCO strap has done a little damage to the top corners of the by-pass bulge, but nothing serious.
I just need to find (or make) some gaskets and wait for the replacement socket-head screws to arrive.

Online Robert Zambelli

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Re: ETA .29 help
« Reply #18 on: November 22, 2020, 05:28:31 PM »
You don't need to make or buy gaskets - use this stuff.
I always replace the paper gaskets with this.
I use it in ALL my engines and never had a failure.

Bob Z.

Offline Air Ministry .

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Re: ETA .29 help
« Reply #19 on: November 25, 2020, 07:55:56 PM »
I think youd better make a free flight open power model for the ETA . Be plenty S/H & cheap about too, Id think .

Online Robert Zambelli

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Re: ETA .29 help
« Reply #20 on: January 16, 2021, 06:47:08 PM »
This sketch represents the internal structure of the ETA muffler.
Exhaust gases enter from the engine into the area surrounding the internal venturi tube.
Ram air enters the venturi and accelerates toward the Vena Contracta, where the pressure becomes lowest.
There is an array of .100 inch diameter holes around .20 inch downstream of the Vena Contracta where the exhaust gases are drawn in by the low pressure.
The combined exhaust gases and ram air exit at the rear.
I tested this system on my Icarus Junior with the ETA 29 as furnished, with the following results (All tests were done on the same day, calm wind, around 75 degrees ambient):
1)   I did not have a sound meter but it was definitely quieter, both on the ground and in the air.
2)   Running Brodak 10/23-50/50 fuel and a 10-6 Thunder Tiger prop, the maximum RPM I could get was around 10,600 on the
        ground with no muffler.
3)   With the muffler, the max RPM increased to around 10,800.
4)   For flight testing, the needle was backed out by four clicks from max.
5)   With the muffler, the lap time decreased from 3.8 second to 3.5 seconds.
6)   Flight time decreased by around twenty seconds with the muffler installed.

The engine is completely stock except for the installation of an ENYA needle valve assembly.
I welcome and suggestions or comments.
Bob Z.

Offline Oldenginerod

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Re: ETA .29 help
« Reply #21 on: January 17, 2021, 04:13:46 AM »
Thanks for the information Bob.  Very useful indeed.  I particularly like the fact that your engine used an Enya NVA, as mine has.
The MERCO muffler is not flow-through and I don't have the skills to fabricate one like you have pictured, although your drawing is very good I must say.
I do have a Macs flow-through muffler but it's rather large, being on a Torpedo .40

Rod.

Online Robert Zambelli

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Re: ETA .29 help
« Reply #22 on: January 17, 2021, 03:24:07 PM »
Hi, Rod.
The sketch does indeed simplify the design but it's definitely more complicated.
There are actually five parts: 
The main body - inner part connects to the engine.
Outer body - connects to main body.
Venturi tube - inside the inner and outer bodies.
Threaded end caps - secure the outer body to the inner body, capturing the venturi tube.
Works very well once I learned that it has to be safety wired!

Bob Z.

Offline Air Ministry .

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Re: ETA .29 help
« Reply #23 on: January 17, 2021, 07:25:26 PM »



Offline Air Ministry .

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Re: ETA .29 help
« Reply #24 on: January 17, 2021, 07:35:07 PM »


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