Engine/Prop Construction
Engine/Prop Construction |
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Date: October 2002 |
Chapter: 17.0 Engine / Propeller |
Section: Power Plant |
This is a really good section that basically requests that you buy the factory engine/prop installation kit, which we did.
Before the mounts can be installed, the firewall protection (a layer of Nomex covered with stainless steel) needs to be installed. First I created a paper template of the firewall to get the shape correct.
Firewall Template
Next I made a rigid template out of poster-board to trace to the stainless.
Poster-Board Template
Then I cut the stainless with tin snips (no easy task, and a good way to ruin a pair of tin snips...).
Stainless Steel Firewall Protection
The next step in preparing for engine mounting is to fit the cowling to the fuselage, and support the lower cowling from below into the position that the upper cowling would support it to. To do this, we built a 2"x4" frame to hold the cowling up. Next the engine will be hoisted into place, with the mount attached to it. The engine will be centered against the lower cowling, and leveled (and the plane is also leveled side-to-side), and mounted 3/8" above center as it will sag when removed from the hoist. Here we've mounted the cowlings and supported the lower cowling.
Engine delivery! Here we're installing the engine mount onto the engine. Luckily we got the folks from Magnum (Gene and Gary) to come out to help, as well as Ray our EAA Tech Counselor, as this was quite a chore.
Gary Works on the Engine Mount
Here we are installing the engine onto the fuselage. First we centered the engine on the lower cowling left-to-right, and then hung it slightly above the center.
Hanging Engine
Hanging Engine
Expanded engine pictures
Fitting the cooling plenum to the engine. Note that the rear-most set of two ignition coils from the previous pictures had to be moved forward to clear the plenum and cowling. Note that once the plenum was fitted, and the runners where sanded slightly to allow them to slide into place, we started to fit the attach points. First the firewall and top three sides of the plenum where masked off with duct tape, and the runner was sanded to accept 2 BID layups for flanges. Once cured, the mating surfaces were drilled and clecoed together, then the bottom of the runner was masked, and the plenum sanded for its flange. Putting this flange on the plenum makes it much easier to install and remove the runners.
Cooling Plenum Fitting
Runner Fitting
Runner Fitting Pilot and Co-Pilot Sides
Runners from NACA Inlets to Cooling Plenum
NACA inlet to Runners and Plenum
Laying Up Flanges on Plenum
Finished Lower Flange and Plenum Opening
Plasma III Ignition Controllers
Here I'm making a notch on the front of the plenum for the LSE ignition coils to fit into. With all six coils mounted on top of the engine, this was required. However, I never really liked how this worked out, since to get to the bottom spark plugs the ignition wires would have to pass through the plenum with a grommet, so I changed the mounting (see next section).
Forming the Bump-out
Glassing the Notch
Another late addition to the bump out, at Jerry's recommendation, was to create yet another piece of glass mated to this surface (in the usual duct-tape over top way), then join them with nut plates, cut opposing slots in them for the wires and hose for removal, and then silicone the lower section to the engine "permanently". Here is how it turned out.
Lower Plenum Half Caulked down
Lower half of split with nutplates and wires/Hose
Finished Plenum
Unlike the in the pictures above, I've moved the ignition coils for the lower cylinders to the firewall, on a custom bracket that I made for them, so the wires wouldn't have to pass through the cooling plenum. Here are pictures of the bracket.
Lower Coil Brackets
Lower Coil Mount
Installed Lower Coils
Lower Coils with Wires
Coax to Upper Cylinder Coils
Here I'm creating holes in the plenum to allow access to the sparkplugs for maintenance. Once I'd created the holes and fiberglass covers, I drilled screw holes and mounted nut plates to secure them with.
Drilled Holes with "Universal Release Agent"
Laying up the covers
Fuel Servo Induction Air Ducting
Rear Oil Cooler Ducting
EGT Probe Installation
The fuel servo installation has been fun. I ended up doing a fair amount of research, and even bought "Aircraft Fuel Metering Systems" from Aircraft Technical Books to make sure I knew what was going on here. Here's a nice drawing I found. From the schematic you can see that the manual mixture control arm is nearest the fuel inlet, and the throttle is near the safetied end nut of the fuel strainer. Thus in the figure below, the throttle has the idle mixture adjustments. The mounting brackets for the control cables are the standard kit from Velocity, but it was a little unclear whether it should go under the servo flange or not. So, concerned that I wouldn't get a good seal that way (see picture below), I decided to mount it on the bottom side.
RSA Fuel Servo Diagram
Here is another drawing, a schematic showing how these things work, and here's a troubleshooting guide for the servo. We've installed dual throttles, so here you can see them converging on the throttle side of the RSA fuel servo - the mixture is on the co-pilot side.
Throttles Converge on Pilot Side
Mixture Control
Fuel Servo from Rear
Servo Control Mounting Brackets
Now we've got to finish up the rest of the connections to the motor. I opted to buy pre-fabricated fuel and oil lines from my engine shop rather than do the factory 'roll-your-own' solution, well, because Gene recommended it and gave me a good deal.
Fuel Pump Outlet to....
Fuel Servo Inlet Side
Servo to "Spider" Valve on top of Engine
Oil Pressure Sensor Outlet
Fuel Pressure Sensor and Switch
Reworked Oil Pressure Manifold
Drilling and Tapping AL Bar Stock to Make Oil/Fuel Sender Manifolds
Here are a couple of interesting points. The first picture is one of dumb luck (bad). I need to drill 2 holes in the fire wall to mount my manifold, and there was nearly nothing inside the firewall. Just this one 3/8" tube. I measured where the tube was, and then where the hole was going to go, and was confident that there was plenty of room to spare. When I drilled the hole, I noticed and odd sense of change-in-resistance as I drilled, and when I peeked inside, found I had managed to dead-eye the center of the tubing. Never in a million years could you do that on purpose. Second is a extra detail, both the electric and engine-driven fuel pumps have internal drains in case they fail, which are routed out of the cowling. Pretty simple stuff.
WTF?
Plastic Fuel Pump Drains
Here, and miscellaneous picture of a detail often unmentioned. As it turns out, at least the way I routed my control wires for the LSE crank pickup, the wires would rub against the fly wheel (it's heavily dished). Here is the poor-man's solution, an AL bracket formed to hold the wires back away from the flywheel. And before anyone mails comments, this fix was recommended to me (and, in fact the part made by) my EAA Technical Counselor/A&P buddy.
LSE Direct Crank Wire-Tie
8/23/07 Here is something else we ran into. After having trouble building RPM and having a very rough running engine that seemed to want to run very lean, and ran relatively well at idle, but not at WOT. We tested the fuel flow from the injectors and found the below. Very uneven flow. After removing the nozzles the flow was healthy and balanced. We cleaned the injectors with an ultrasonic jewelry cleaner and with Hoppe's Elite gun cleaner. After that I still had to blow air from my compressor back through them to get all of the debris out. We then cleaned up the spark plugs with a propane torch per a recommendation from Klaus at Light Speed and now everything seems to be in order.
Fuel Flow testing at Injectors
Two runs of 1/2" 3003 Aluminum tubing are run from the firewall up to the nose of the aircraft, and then covered in heat shrink tubing to add some insulation value to the line. At the aft end, the lines are installed with nuts and unions to a pre-made (by the factory) plate, and safety-wired. At the nose, we needed to install a 2-way valve so that we can select to heat either the fresh air oil cooler/cabin heater, or the recirculating air cooler/heater. An aluminum bracket was installed to hold the valve steady against the load of operating the valve, and stainless steel flexible tubing was run to and from each cooler/heater.
Oil Tubing with Heat Shrink
Oil Lines at Firewall
Oil Diverter Valve Installed
Oil Tubes Return Tee and Supply 3-Way valve
Oil Tubing to Both Nose Coolers/Heaters
Here I'm fitting up the prototyping components from Aircraft Exhaust.Net. They sent use 6 stubs to mount to the engine exhaust ports and a collector, though I elected not to use the collector. The nice thing about this system, is you can get what you think you want exactly in cheap PVC, and then send it to them for fabrication to your specifications. I think that this is going to work out really well for us. We're going to eventually mold exhaust augmenting ducts on to the cowling so the high pressure exhaust flow pulls a slight vacuum on the cowling (and lower portion of the engine) to improve cooling air flow, especially on the ground. This will also cool the exhaust stream before it reaches the prop, and provide some thrust (rather than the typical aerodynamically ruinous rooster-tail effect the factory exhausts create). Jack Morrison of E-Racer fame has done this sort of thing with his supercharged Magnum engine, and is very pleased with the result, so we're hopeful (check him out in the November 2003 Sport Planes Magazine).
Pilot Side Exhaust Stack
Close-Up Pilot Side
Pilot Side Cowling Cut
Exhaust Mock-Up Looking from Rear
Cowling with Mock-Up from Rear
The Finished Exhaust
Exhaust from Behind
EGT Probes Installed
Exhaust Safety
Coming out of the sump is a fuel shutoff valve, ours is controlled remotely from a T-handled lever glassed into a pocket on the keel (Section 14.7), and then exits the firewall through a bulkhead fitting. On the firewall, the fuel tubing goes to a cleanable strainer, the electric boost pump, and then to a Floscan fuel flow transmitter. I've allowed a fair amount (though not quite the recommended 12") of straight tubing before any 90 degree bends to get more accurate flow readings. A 3 ply Triax layup was made to create a fuel pump and fuel filter mount.
Making a Fuel Pump Mount
Pump, Filter, and Flow Transmitter Mounted
This section is not compete.
The Pilot's side controls have been installed. After the panel was modified in Section 13.2, the engine controls were installed in their usual order. The throttle is a simple push-pull with friction lock, whereas the prop and mixture are vernier style. The copilot side will later get a non-friction locking push-pull throttle for flight operations from that side. We are planning this for simplicity, with the limiting assumption that this will not be the primary flight station. If the copilot controls are used for relief and emergency only, then the pilot can set the mixture and prop full in for takeoff and/or landing prior to giving the ship to the copilot. We felt that we wanted the vernier style controls on the prop and mixture, and trying to connect these in a fully redundant system was considered overly complex. Towards the aft end of the control assembly, a second triax support was installed to aid the controls in resisting any twisting moments. We saw this installed on the factory birds and thought it was a good idea.
Engine Control Bracket
Engine Control Bracket Installed / Run Aft to Engine
Pilot Side Controls
Copilot Side Controls
Pilot Side Close-up
Copilot Side Close-up
The control cables enter the pilot side duct/conduit behind the instrument panel and discharge under the oil lines at the aft end / firewall.
Engine Controls at Firewall
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Pressure check was completed as part of the strake completion work.
Site gauges installed in Strake chapter.
The engine plenum that we showed you above was a little too big, it was for the 300HP IO-540-K "angle-valve" motor. We have the IO-540-D, which is normally a 260HP motor, although ours is pumped up with high compression pistons and electronic ignition to above 300HP. Here are pictures of us glassing the fore and aft halves of the plenum, so that there's a lip from the aft section over the lip of the ore section. This will have nut plates installed for screws later.
Preparing the Fore Plenum to Release Fiberglass Lip
Lip being Glassed onto Aft Plenum
Here we're glassing flanges onto the runners. The runners have lips on the firewall end on both sides and the bottom, the top has to be flush against the cowling when mounted, and it shares the retaining screws with it on top. On the plenum side, the runner has flanges on top and sides, and the plenum gets a flange on the bottom side to allow for easier installation and removal. Once the runners are glassed, the plenum is trimmed inside the runner mouths to allow for the cooling air to pressurize the top side of the motor, and flow down through it's cooling fins.
Runner to Plenum Flange Preparation
Runner to Firewall Flange Preparation
Glassing Lower Runner Flange
Finished Flange and Runner Opening
Next we need to make access holes for routine maintenance items so that we don't have to remove the plenum to check the oil or change a spark plug. Here we're preparing the oil dipstick access hole and cover. I started to make a screw-down cover for the dipstick, but after seeing Rich Guerra's setup I decided to go with the 'recessed cup' configuration. I took a wax cup that I cut the bottom out of and then cut the side of to create this cup. I taped the wax cup wall back together in the diameter that I needed, and then made a 4 BID layup on the outside. I then cut that to extend just below the dipstick, where the diameter of the dipstick tube changes, and glassed to the plenum. I think took a piece of 2 Triax that I'd laid up flat previously and cut a dipstick-tube sized hole in it, and cut the outside diamter to fit the bottom of my cup, and then glassed it to the plenum as seen below. Sound tedious? I assure that it is. The upside is I got mine tight enough that I have to remove the dipstick to pull the fore section of the plenum off. NICE.
Oil Dipstick Access Hole
Abandoned Oil Access Cover
Oil/Dipstick Access Cup
Oil/Dipstick Cup Internal Detail
Also in this section, we have to make a mating flange for the fuel servo, where the fuel is mixed with induction air. Here I've taken a piece of scrap aluminum with a paint cap glue to it, and then waxed and covered with a mess of BID. Once cured, just pop it all apart and trim.
Fuel Servo Flange
This section is not compete.
This section is not compete.
Our Catto prop is on order with Craig Catto, though we still need to give him final horsepower figures from our test runs with the engine. We believe that this will give us the best overall performance, although we may switch to a constant speed prop later if we find the takeoff performance unacceptable. The folks flying Velocitys with Craig's props are all reporting good results and high satisfaction.
We've elected to go with a spinner from Ken Miller, with the 'reverse taper' design and a lampshade flowguide to get the best airflow through our prop.
Ken Miller 'Hershey Kiss' Spinner and Lamp Shade Flowguide
Fitting Propeller
The Propeller arrives
Catto Propeller
4/11/2006 - We've begun to fit the prop and spinner. We have to put the propeller on and take it off several times to get the spinner installed. First we have to mark where the blades intersect the spinner bulkhead, and then make templates of the blade so we can cut the openings for the blades to stick through. I've got a 4" Saber extension, but it seems most folks are running 6" extensions, so I'm deciding if I want to swap it out now, or wait to see how our Weight and Balance works out first. For more detail on the prop/spinner check out this page.
Catto Prop
What an awesome site - This is one of THOSE days
The nose oil cooler takes air from a NACA scoop installed on the left side of the fuselage. This opening was prelocated by the factory, and cut and installed it during Head Start much like the other NACA scoops. Then the supplied ducting was cut, the upper section was covered with foil tape and laid up with BID to create a mating flange on the lower (outlet) section. Then a hole was cut in the lower fuselage to allow the oil cooler to vent overboard. This is tricky all-round, and I chose to clamp the cooler in place on the NACA to get the best positioning possible (and still ended up back filling some).
Fitting the Oil Cooler Duct
Setting the Oil Cooler Duct
Next two holes are drilled in the duct for the hot air outlet, and the aluminum sheet is cut per the template to form the flapper valve. Once the hinge is attached to the flapper, it can be located and attached to the duct, and then the outlet tubes can be glassed into place and the control cable attached. Finally the oil cooler is attached to the NACA with #10 sheet metal screws.
Making the Duct Center Flange
Making the Oil Cooler Flange
Dry-Fitting the Oil Cooler
Protecting the Oil Cooler for Flange work
Setting the Outlet Ducts
Oil Cooler NACA Duct
Next, we added an additional cooler in the nose for supplemental heating. This cooler (or heater from the perspective of a passenger) will heat on very cold days were we want to recirculate cabin air through to warm it, instead of bringing in zero degree outside air. This was an idea from Bill Stockmon, a builder from Dayton who was kind enough to take me flying. He had rigged a somewhat less elaborate system of using a computer fan and things. We'll be using a marine bilge fan and a permanently installed secondary heat exchanger, ducting, and 3-way valves to select which is active (on the oil side). My thinking is that I'll switch over from say September to March here in Oil. As you can also see in the attached pictures we'll be taking the cool air from the copilot side NACA duct and running it to mixing valve from Spruce along with the hot air, thus providing air of just the right temperature to the cabin (I hope, anyway). This should do away with the Cessna-style (exhaust muff) phenomena of getting no heat, or a rush of 150 degree air on your leg (especially nice in Fall when you're wearing shorts, but it gets cool at altitude....). We're also going to use the keel as a heater duct to route the air to the passengers (which is possible with the fixed gear plane, with far less equipment in there), which is an idea that the factory kind of liked.
Fan, heat exchanger, and exhaust plenum
Recirculation Heater Installed
Ducting from Front
Ducting from Rear
Heater Outlet Nozzles
We recieved overhead NACA scoops rather than the older style Belly Scoop. This is discussed here. The combustion air will be ducted once the engine is hung.
This section is not compete.
The rear mounted oil cooler comes as a kit from the factory. After some playing around with the three pieces and looking at the pictures on the factory website, it becomes apparent how this goes together. Basically you drill a 4" diameter hole in the cover-plate and install a ducting flange with pop rivets, then rivet the standoff brackets such that they form a chamber with the firewall. The exit of the cooler dumps into the cowling. We will be installing an exhaust augmentation system that will draw this hot air, along with that coming down from the roof-mounted NACA scoops, out of the cowling through Bernoulli effect of the exhaust pipes jetting through an escape duct (thereby creating a slight vacuum).
Rear Oil Cooler Bracket
Now that we have the mounted and figured out where the fuel components will go, I've mounted the rear oil cooler. Here, I've opted to make some 'ears' for the rear of my factory-supplied oil cooler mount since there was a significant gap back there where air could escape without going through the cooler. First I made a cardboard template, and then cut these out of some scraps of multi-ply TRIAX.
Oil Cooler Ears
Rear Oil Cooler Mounted
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~ End of Chapter ~ End of Section ~