Manifolds

Building Tips
Introduction Wing Joining Wing Ribs Graphics Thrust Angles Manifolds Exploding the Myth

On a recent model aircraft (a Dave Smith Models Excelsior 150) that I was building and which was to to include a tuned pipe, it looked like I could almost totally enclose the pipe if the manifold could be brought out the rear of the engine and through the firewall. The engine in question was an MVVS 61 which I had bought from Just Engines and was just looking for a new home. This engine can easily be converted to a rear exhaust port by removing the four head bolts, removing the four cylinder to crankcase bolts, rotating the cylinder 90° and re-fitting all the bolts.

The neat installation of the MVVS 60 and manifold can be seen here. The manifold comes out of the rear of the engine and through the firewall. Only the needles protrude through the cowling. Despite being a "longstroke" engine, the Excelsior cowling hides the engine well. The engine has 3° sidethrust and 1° downthrust with offsets to match and a Perry pump and the manifold coming out the rear. Shoehorn is an optional extra! Move mouse over image to see another picture.

With this thought in the back of my head, I build the model up to the point of engine installation and with all the nose region finished. Now came the problem! I 'phoned Paul Landels at Just Engines to see if they had any rear exhaust manifolds for the MVVS. From past experience, I knew that they carry a wide range of exhaust, pipes and manifolds so this would be my starting point. Paul told me that if I could send him a sketch of what I was looking for, they could probably have it made for me. A bit of paper, ruler and some measuring later, I had produced a rough sketch showing engine position, exhaust port, firewall and surrounding structure. I used AutoCAD LT (once again) because I have it. I figured Paul probably wouldn't be able to use an AutoCAD file so I converted the drawings to gif format so a web browser would be able to open them - we're not talking ace drawings here, just enough to let Paul know what I was looking for.

I e-mailed the files and followed this up with a 'phone call the next day. As you can see, the installation called for a fairly sharp bend coming out of the manifold. The (inverted) engine has 3° of side thrust and so the exhaust port is 4mm (0.150") offset to the fuselage centreline. Much to my surprise, Paul seemed to have no problems with my design - that's a first for me! Obviously, I could use the trusty Dremel to remove any required material from the firewall and tank floor to accommodate the manifold.

Because of my usual "ace" planning, I wanted the manifold over the Christmas/Millenium period - so it would probably be a couple of weeks before I got it.

The manifold duly arrived pretty much with the first post of the Millenium - an outstanding achievement!. Ten minutes later and surrounded in a cloud of balsa dust, the manifold was fitted and it was perfect - it's amazing when a plan comes together! The manifold is completely concealed in the fuselage and it fits perfectly. This makes for a really neat installation.

The wings and pipe are strapped on and you can see how well the manifold and pipe are concealed in the Excelsior's pipe tunnel. Not at all bad for a model having only a 1.5m (59") wingspan. The neat installation of the MVVS 60 and manifold can be seen here. The manifold comes out of the rear of the engine and through the firewall. Only the needles protrude through the cowling.

 

 

 

 

 

Normally I just buy "off-the-shelf" parts and make the model fit the parts. Having seen how easy it is to get something custom made, I will definitely change the way I go about fitting tuned pipes to my models.

Building Tips
Introduction Wing Joining Wing Ribs Graphics Thrust Angles Manifolds Exploding the Myth

The neat installation of the MVVS 60 and manifold can be seen here. The manifold comes out of the rear of the engine and through the firewall. Only the needles protrude through the cowling. Despite being a "longstroke" engine, the Excelsior cowling hides the engine well. The engine has 3° sidethrust and 1° downthrust with offsets to match and a Perry pump and the manifold coming out the rear. Shoehorn is an optional extra!
The wings and pipe are strapped on and you can see how well the manifold and pipe are concealed in the Excelsior's pipe tunnel. Not at all bad for a model having only a 1.5m (59") wingspan.
The neat installation of the MVVS 60 and manifold can be seen here. The manifold comes out of the rear of the engine and through the firewall. Only the needles protrude through the cowling.