Engine Mount

[lv2plyguitar 172]

Hi,

 

Is 4130 the typical tube steel used to fabricate a motor mount?  If so what should the inside diameter be if I am going with 3/4.

 

Thanks

[akflyer 1427]

what engine are you putting on it?

[lv2plyguitar 172]

o-200.  I saw a Cessna 150 mount and it is pretty light.   I am looking a engine mount plan for a o-200 in a merlin.  It does not specify whether its 4130 or the inside dia.  Just says 3/4 x 035.

Engine Mount Drawing.pdf

Edited 12 Feb 2015 by AVID STOL HH

[EDMO 1078]

Sometimes you are better off to buy a standard mount for the engine, and modify the fuselage to fit it.

EDMO

[thebriman 69]

If its tubing its most assuredly 4130.  3/4x.035.  3/4" is the O.D., .035 is the sidewall thickness.  to figure your I.D. you can take 3/4" or .75 minus your sidewalls (.035) being .070. and you get .68.  That's your I.D.   

[Luked 71]

Looks like the drawing specifies 1025 steel. Most motor mounts I have heard of are 4130 though.

[lv2plyguitar 172]

Im thinking 4130 also.  A Cessna 150 with a o-200 motor mount is actually smaller than 3/4 tube.  IT is very light and is 4130.

Edited 12 Feb 2015 by AVID STOL HH

[akflyer 1427]

1025 is the tubing piper and most other AC manufactures used 100 years ago before the 4130.  Most all tubing used now is 4130.  If the .035 wall 1025 was good enough to hold, .035 4130 will be an upgrade.  I would use .035 4130 in a heart beat and not think twice about it.

 

[lv2plyguitar 172]

Attached is a Merlin with o-200 installed.  The mount in the picture is what is on the plans. The second picture is the engine I bought out of a federal repo.

 

 

Edited 13 Feb 2015 by AVID STOL HH

[akflyer 1427]

The drawing you posted uses 5/8" and 3/4" tubes.

 

[Avid90 12]

     ...So the engine mount drawing is for a Piper Vagabond with the Continental 65 horsepower engine.  Piper used lots of 1025 tubing in their steel tube structures.  They used just a few sticks of 4130 in the more highly stressed areas.  I've been told that the cost savings per airplane for doing this was about $4.00.
     That Vagabond engine mount sits pretty close to the firewall.  Are you intending to use a starter and generatior on that 0-200?

[EDMO 1078]

Wasn't the Vagabond PA-15 equipped with the C65-8, with no starter, generator?

What about the Piper Colt? Didn't it have electric?

Does the mount for the C65-12, C75-12, C85-12, and C90-12 fit the O-200? There should be plenty of them around.

EDMO

[Av8r3400 1179]

The PA-15/17 had th C65 as the stock motor, no electrics.

Piper PA22 Colt had a O235 Lycoming, the PA20/22 Pacer and PA16 Clipper had an O290 Lycoming, all with electrics.

I don't believe the C and the O Continental mounts will interchange without some mods. Obviously the Lycoming mounts are totally different.

[lv2plyguitar 172]

_{My engine definitely will sit out further from the firewall.  The drawings are definitely the firewall dimensions for a Merlin GT as the measurements line up perfectly.}

[EDMO 1078]

For 3/4 x .035 wall 4130, the tube that would fit closest to the inside would be 11/16 or .680 OD.

EDMO

[Av8r3400 1179]

Remember, you're putting a 200+ pound engine in a plane designed for a 75 pound two stroke. You will need to do something to balance it out.

Have you looked at the fuselage stretch?

[lv2plyguitar 172]

_{The online Merlin Brouchures advertised a Rotax 912 as a power option.  The Merlin has had no structural changes to the firewall or airframe since the Merlin GT.  However I will be carrying an additional 20 pounds up front compared to the Rotax 912.  I am planning a battery in the back, heavier tail wheel and some structural additions to keep everything within CG and safe.  Stu in Canada put a o-200 in his merlin with no structural modifications but only putting the battery in back.   He flew it for years with no issues.  He actually did a trip from Canada to California.  The Merlin is longer than an AVID Plus and has a 42" wide cockpit.  No real big issues to deal with. There are also several merlins online that have the corvair engine in them as well.} 

[akflyer 1427]

I'm thinking your going to have a very fun bird Jeff!  Are you going to use an avid mixer system in it?? I would keep the separate flaps and ailerons. 

 

[lv2plyguitar 172]

I am going to use the avid mixer system in it.  The merlin had not flaps, only the full length aielrons.  When I was flying my avid they were very effective as a flap.

[lv2plyguitar 172]

Leni, you can get a Macair Merlin with a C-85 for 12,000.  Needs recovered, new plexi, and engine gone through.

[akflyer 1427]

Leni, you can get a Macair Merlin with a C-85 for 12,000.  Needs recovered, new plexi, and engine gone through.

 

I gotta get the 180 repainted and back in the air before I even think of another plane project

[lv2plyguitar 172]

You have forsaken your people by owning a certified airplane. 

[Av8r3400 1179]

Just say hi to Leni as you go past the cardboard box he will be living in, next to the airport.

I just hope he has Internet there to keep the site up and running.

[akflyer 1427]

I have not forsaken my beloved brethren, I still have the Avid and its not leaving the stable anytime in the foreseeable future.  I have a partner in the 180 so I at least get to live in a 2 story cardboard box   I got wifi in the igloo mr so no worries about keeping the site up and running

 

[EDMO 1078]

Here is the scoop on Continental motor mounts - There should be lots of old Piper mounts around. But remember, lots of Pipers didn't have starter or electrical. It has to be for a -12 engine to have enough space for the starter.

When the C-65 was replaced by an O-200 on my friend's Luscombe, he used the C-65 motor mount - The O-200 uses the same case as the C engines, but the mount holes in the O-200 case are larger and use larger rubbers - They put bushings in the O-200 case holes to take the smaller (bolts?) rubbers. Guess this makes sense?

The C75,85,90 mounts are the same as the C65 - I would bet that Piper never changed the mount design for any of them. When we put the C90-8 in the J3, the original C65 mount and rubbers was used.

I don't know which Piper models used Continental engines with starters.

EDMO

Edited 14 Feb 2015 by Ed In Missouri