Comparison of Engines

[Zuriel Armstrong]

I have been reading about 60's era stunters and find many European and Australian modelers used the Merco 35.  Having never seen one, could someone give a comparison to what modern engine my be it's equal.  Power, weight, etc.  It seemed they flew some rather large planes with this engine.  I already know I could put an LA46 in most of these designs

Thanks.

[Robert Zambelli]

Z-man - seems like there were a number of Merco 35s and I'm sure someone else is more knowledgeable than I but it seems like the earlier ones with the one piece crankcase (Like a Fox) were very good stunt engines. I have a .29 and a .35 and they both to run exactly like a Fox, with possibly a bit more power. They were redheads.
We experimented with the later versions that had separate cylinder fins but we never had much luck with them.
There was yet another version with an interesting muffler setup that appeared to run quite well.

There's a fellow caller "Rustler" who as I recall is quite the specialist with Merco.

Bob Z.

[rustler]

Z-man - seems like there were a number of Merco 35s
it seems like the earlier ones with the one piece crankcase (Like a Fox) were very good stunt engines. I have a .29 and a .35 and they both to run exactly like a Fox, with possibly a bit more power. They were redheads.
We experimented with the later versions that had separate cylinder fins but we never had much luck with them.
There was yet another version with an interesting muffler setup that appeared to run quite well.

There's a fellow caller "Rustler" who as I recall is quite the specialist with Merco. Bob Z.

There's only one basic Merco 35, but the company passed through various owners' hands. Those made by the first two owners, Merco (Model Engine Research Co.) and Denis Allen (Allen-Mercury) were excellent motors. Subsequently quality could be a bit variable. Forest Engineering were not too bad. Gotta say that because I was half of Forest!
The first ones had bushed c/shaft bearings, but this was later omitted and a bigger shaft fitted.

Ones with separate cylinder fins - would be by the Premier Co., or possibly Merco Engines. Could be variable.

The "interesting" muffler setup might mean the 40 I do. Entirely new design, and strictly speaking a Rustler-Merco.

Recommended reading is under "Merco" on Dave Day's web site.

The early ones which were used in some bigger/heavier models would have used a %age of nitro in the fuel, and no muffler.

[Zuriel Armstrong]

Bob and Ian,

Thanks for the responses.  Did they weigh comparable to the Fox 35?

[Robert Zambelli]

Hi, Z.

Not sure on the weight but I suspect it was close to the Fox.
Possible a bit more as it had a 4-bolt backplate.

You've encouraged me to do a test. My Merco redhead has very little time on it - basically new-in box.
I will run it in and try it in place of the Fox 35 on my Nobler.
Should be interesting.

Ian - question. My Merco does not have a muffler. Do you know if there any issues in fitting one?
Speaking of the 40 - a few years back, someone sent me one to test. I flew it and then passed it on. It ran like a clock - virtually perfect stunt runs, after I made a new venturi.
Bob Z.

[dennis lipsett]

I got my first Merco 35 Redhead from a friend in England in the late 61. It became my favorite engine for quite awhile and was in my opinion a far better engine then Duke's 35.I retired it for awhile when I lost the propnut and couldn't get a replacement for it. S.A.E/ whitworth threads were impossible to find in my neck of the woods.
I ran the 49/60 and a few of the blackhead 35/40's in the late 60's to the 80's
I had the Premier plastics 30/40 and 30 diesel. My diesel was carefully broken in and ran well but broke it's shaft on the first flight. Hobby lobby replaced it with a new one and I still have it NIB. I managed to get the 60 diesel before they went belly up. The Premier 30 glow was actually a nice running engine and I used is on a few sport models. The 40 is still NIB.
The early 49 and 60 were absolute jewels and ran like Swiss watches..
Oh and the redhead 35 likes about an inch more pitch then the fox.
Dennis

[Bill Little]

Hi Z-Man,

I really like the early Red Head Merco .35  I recently got another one in trade from a friend in England, and I am waiting to fly it.  The one I first had was a great stunt engine.  It reminded me of a Veco .35 Stunt, and almost equal to a McCoy .40RH.  Nice break, and more power than a Fox .35, with same nitro, etc..  Very similar to the OS .35S in power IMHO.  A really good engine, as far as I am concerned.  A "modern" equivalent?  Don't guess there is one.  Not as strong as an OS .46LA, never tried a .40LA (and probably never will), and doesn't compare in power to an AT .36.

I would like to try one of Ian's "new" .40s.  The ones I have seen are excellent.

I am looking forward to running this one.  it will be in a 1956 Ken Taylor (Australia) design called the Centuar.  A nice looking stunt ship, very much akin to the '60s USA designs, and it has an upright engine!  So the old Red head sticks right out.

Bill

[Zuriel Armstrong]

Bob & Bill,

I am interested in building an Australian Classi called Angelique.  It is a large airplane and was originally powered by a Merco 35.  I have had the plans for a few years now and would like to get it done.  It has a 62" span and a long slender fuselage.  I have no idea of the weight of the original or those that followed.  It was an Australian Nat's winner and I suspect a good flyer if build light and true.

This photo is from Peter White's plans service.

[dennis lipsett]

Bob & Bill,

I am interested in building an Australian Classi called Angelique.  It is a large airplane and was originally powered by a Merco 35.  I have had the plans for a few years now and would like to get it done.  It has a 62" span and a long slender fuselage.  I have no idea of the weight of the original or those that followed.  It was an Australian Nat's winner and I suspect a good flyer if build light and true.

This photo is from Peter White's plans service.

That is a really nice looking model.
Dennis

[rustler]

I will run it in and try it in place of the Fox 35 on my Nobler.
Ian - question. My Merco does not have a muffler. Do you know if there any issues in fitting one?
Speaking of the 40 - a few years back, someone sent me one to test. I flew it and then passed it on. It ran like a clock - virtually perfect stunt runs, after I made a new venturi. Bob Z.

Hi Bob. Yours sounds like an early Merco 35. If so, don't be discouraged that it needs a lot of old fashioned running in. If I recall correctly, 2 hours plus on the bench? Do this and you will be well rewarded. (Rather like the old Enyas).
So many customers complained at this that later they were set up looser.

Mufflers - I guess yours does not have muffler lugs on the exhaust. The first Merco muffs had a threaded rod which went round the back of the engine. This should not be overtightened in case it distorts the case. Best gently firm with shakeproof washers. I usually have these in stock, but am out at the moment. And of course, it will take any muff which is made to fit, with no worries other than whether the muff is of sensible design, e.g. if it has a 1/16" outlet it might cut the power a little!

[Russell Bond]

I have spoken to stunt fliers that were around in the '60s and saw models like the Angelique fly and they said the plane flew well but was VERY light on the lines. (With a .35.)
You had to be careful flying them or you would lose line tension easily.
Also, these (.35) motors were run with no mufflers in those days which gave them more power.

There is a flyer here in Adelaide (South Australia) that has an Angelique that has an LA46 fitted. Seems to fly well.
I certainly would not put anything smaller than a .46 into an Angelique and also keep it light as the wing is thin.

In regards to the Nobler, the Merco is a little heavier than the Fox so you may have to add tail weight. The Merco has more power than the Fox, so no problems there.

[Brett Buck]

Hi Bob. Yours sounds like an early Merco 35. If so, don't be discouraged that it needs a lot of old fashioned running in. If I recall correctly, 2 hours plus on the bench? Do this and you will be well rewarded. (Rather like the old Enyas).

   Heck, same as the Fox, too. While you can frequently get them to run reliably (i.e. without just quitting unexpectedly) with as little as 45 minutes of bench time, both of the engines I had extensive experience with took an absolutely incredible amount of flying time and fuel to get really right. On the order of 10 *gallons*, which is an awfully long time and a lot of flights at 4 oz. per. I am pretty well convinced that the culprit is the bushing, not the piston/liner fit. Some had clearly gotten to the point that the compression was at least past its peak but they still had better overall power and much better run characteristics. I think this was pretty well known back in the day, but I didn't know that and it came as a surprise to me.

  I also think that grinding away for hours on the bench is not enough. Even current engines need at least some actual flying time, but these old guys seem to need a tremendous number of flights to get good.

   Brett

[Paul Taylor]

Bob & Bill,

I am interested in building an Australian Classi called Angelique.  It is a large airplane and was originally powered by a Merco 35.  I have had the plans for a few years now and would like to get it done.  It has a 62" span and a long slender fuselage.  I have no idea of the weight of the original or those that followed.  It was an Australian Nat's winner and I suspect a good flyer if build light and true.

This photo is from Peter White's plans service.

Zuriel,
I am glad you picked a plane that has a rudder, now if we can just keep you from painting it PINK!

I think you are a little "Out of your Mind". You have to finish your current project before you can start on anything new. And Oh yea.... you have to get your Bi-Sob repaired.

[Robert Zambelli]

Hey, Brett - good point about the long run-in times.
Although the old Enyas and Os engines seemed to require lots of time, the Foxed were just plain inconsistent.

Case in point. I found two old but NEW-in Box Foxes at my local hobby shop. They were manufactured around the same period.
Both were removed from the box and put on a test stand - no disassembly whatsoever.
After around 20 minute run time, one engine would hold a perfect lean setting, the other would not. 
I put it one a plane and it ran perfectly without ever an abrupt stop in flight. I run it on my Stinger, screaming lean with a 9 1/2-6 APC.
The other one required almost another 1 1/2 hours before it would run properly. Regarding stunt runs and two-four break, it has become the best running Fox 35 stunt I've ever owned.
Both were run exclusively on 10-22 or 10-23 fuel with 50/50 castor/synthetic.

But, back to the original discussion - Merco.
Here are some pictures comparing the Fox to the Merco.
All dimensions are different so there is no way to bolt the Merco in to replace a Fox - everything is bigger.   

Bob Z.

[Bill Little]

Thanks for the pictures, Bob!  Like I said, the Merco reminded me a LOT of the Veco of the same period.  Almost a copy from the looks of it back in the day.

I missed the part of any one saying it was a direct bolt in.  the only engine I know that is a direct bolt in for the Fox .35 is a DS .40 (almost a perfect swap).  And with proper venturi, head shims, etc., the DS does become a fairly strong .40, although nothing along the lines of the Aero Tiger .36 and such new "CLPA" stunt engines in the .40 range (PA, Ro-Jett, etc..)

[john e. holliday]

I had one of those Mercos.   The guy I got it from bought and then decided it would not make a racing engine for Rat Race.  About the third flight in the air, it was a great engine for stunt as it came, the glow plug went somewhere.  The threads were gone in the head.  Fortunately for me an old Fox Combat Special head fit like it was made for it.  Still ran great and was an easly starter.  Don't know what happened to it as I haven't seen it in years.  Maybe still in my stash somewhere.