Once the cowl lips were done I went back (or forward) to Chapter 25 to do primary finishing on the canopy, then to Chapter 15 to do the firewall. Chapter 16 and 17 snuck in again while I refitted the control linkages, finished off the rudder cables and fitted the electric trim.
Note: I made the cowling later. See Covers & Fairings
The distance from the firewall to the flywheel on Jeff's IO-360 installation is 31.75 inches. Jeff has a 2 inch flange and an 8 inch prop extension making the distance from the firewall to the forward face of the prop 41.75 inches. Nat tells me that the plans engine mount is 10.5 inches, the distance from engine mount to flange is 22.2 inches and the prop hub extension is 8 inches giving 40.7 from firewall to prop. I got the following numbers from Nat:
A, Firewall to mount point = 10.5 (plans) B, Mount point to engine flange = 22.2 (plans) C, Length of prop extension = 8 (measured) D, Firewall to prop = 40.7 (calculated) E, engine C of G to engine flange = 14 (estimate) And the following numbers from Jeff: A + B, Firewall to flywheel = 31.75 (measured) C, Length of prop extension = 10 D, Firewall to prop = 41.75 (measured) E, C of G to engine flange = 14 F, Firewall to engine C of G = 18.75From these numbers it seems that, either Jeffs engine is one inch further back than Nat's, or we have a minor measurement error. I suspect the later. Anyway, I think the ideal distance from firewall to forward face of prop is about 41 to 42 inches, and the plans engine C of G is about 18.7 aft of the firewall.
Nat says that the 0-360 Lyc weighs in at around 310 not including prop extension. I weighed my '93 13B REW and accessories on a UPS scale as follows:
Engine less oil pan 178 Smog pump 7 Starter 8 water pump 10 Alternator 11.5 total 214.5Add in the redrive at 35 lb, the mount plate at 5 and about 5 lb of water and we come to about 260 lb for the 13B compared with the Lcy at 310. Of course there will be other items like prop extension, oil and mount, but these will be about the same on both. So, if we have a difference of around 50lb, does this mean I should mount the 13B aft of the plans point for the Lyc to keep the airplane C of G in the same place? If the recommended engine C of G is x inches from the aircraft C of G how far aft should the 13B go back to compensate for 50 lb? Hmmmm. I'm thinking that I might be able to move the engine back and shorten (or do without) the prop extension. ....or perhaps I'm being a bit anal trying to calculate all this stuff. So be it. The plans engine C of G is 18.7 aft of the firewall. Given Lyc weight of 310lb this equals a moment on the firewall of 483 ft lb. The 13B weighs 260lb. Lets add 20lb for some extras. Say 280. To get the same moment the C of G of the 13B needs to be 20.7 inches from firewall (2 inches aft). If we use the 260 lb figure the C of G goes at 22.3 The 13B is a small, short engine. It will be interesting to see where this puts the prop flange. Interesting stuff. I hope I get it right.
Bulent, Ed and I worked for about 9 hours to get the engine firmly positioned where it needed to be in relation to the false firewall. We began by marking off the engine mount points and center of thrust on the firewall. Next we installed the Barry mounts and washers. The firewall was aligned at 90 degrees to the metal work table and bolted firmly in place. Bulent had prepared a 1/4 inch AL plate to go between the sump and the engine to act as a mounting support. After match drilling a few holes, this plate was installed and the engine suspended in rough position. Vertical position was set with the thrust line at WL 21.5 (1.5 below the top of the longerons). Now came time for positioning forward and aft. I had calculated that we wanted the C of G 20.7 inches from the firewall. Bulent knew we needed the prop flange at 41 inches. There was a lot of discussion as to which measurement should direct the position. I felt that the prop flange position should be adjusted with a prop extension. Bulent suggested that the C of G could be moved by alternate battery placement. I argued that I'll be using a very light battery and I know where I want it. I won the debate and we positioned the engine C of G 20.7 inches from the firewall. Once we had it in place we measured the position of the prop flange. Wow. Thank you Tracy Crook. You made the redrive the perfect length. 41 inches on the dot. We spent hours making minor adjustments to all three planes using rulers, a spirit level and angle finder until we had the engine perfectly placed horizontaly, verticaly and fore aft. As we got each plane correct, Ed ran around welding steel bars to the metal table to hold everything in place. Ed uses welds like like most of us use clamps. We added a 1.5 degree angle to the thrust line (prop higher than firewall end) to counteract the angle of the fuselage at cruise. Later Ed suggested that we change this to 2 degrees. Why 2 degrees? "Everything sags!", says Ed, "Everything!". We made it 2 degrees.
While all this was going on, I had a problem restarting my big old Suburban truck and had to install a new starter, then a battery. At one point I came back to the truck to find Dion Curtis, who works in a nearby shop, under the truck. He just decided I needed some help and pitched in. What a guy! With Dion's help and Ed's tools I eventually got back on the road.
We left Ed with the engine fixed in place, ready for him to build the mount. He will be making two, one for Bulent and one for me. He'll build a jig around the first one so can make a second identical unit. If you're planning to mount a 13B to your Cozy IV using Tracy's redrive, now might be a good time to call Ed (954-784-0134) and have him build one for you. The more the merrier!
Ed took a while to get around to making the mount. I dropped in a few times to "shake his tree" and finally, one day in March '01, I actually caught him working on it. The mount was completed on April 1st. Hmmm. I drove down to Ed's in my truck to collect the mount and engine. To my untrained eye the mount looks like excellent work. It weighs in at 16 lb including the 1/4 aluminum plate which makes up almost half the weight. Ed had painted the finished mount with black epoxy paint, and even added a welded steel stand to the firewall. Ed tells me that he already has another order for a Cozy mount.
An alternative which has since surfaced is Fred Breese at Conversion Concepts As of August 2002, he makes a nice looking production 13B mount for RVs, and is working on one for the Cozy IV. In retrospect I think I'd prefer Fred's setup with the rubber mounts on the oil pan plate, and it sure would have been easier to just call and order, rather than invent. Of course someone has to fly the first one, but things are improving in Wankelworld!
Anyway. The dimensions of my mount shown in the picture are:
A - Long top tube - 26.5 B - Short top tube - 17.5 C - Short lower tube - 18.5 D - Long lower tube - 27.5 E - Vertical tube - 15.5 G - Mount plate - 15 (fore aft) * 16 (width) 1/4 al plate F - Firewall to forward face of flywheel - 27.7The above figures are approximate for the longest part of each tube. The mount points on the firewall are per plans, except that the lower two are about 1/4 inch inboard to make room for the bushings. If you look at my weight and balance figures calculated in the prefilght section, you'll see that it wouldnt have hurt to have the engine an inch or so closer to the flywheel. For relatively light pilots like myself this would have reduced the amount of solo ballast needed.
I dropped in to see Buly at Ft Lauderdale Exec on the way home - he was at lunch - and gave Chris a final call at 12:30 pm before heading North. He picked up. He'd been up late the night before and had just woken up. He needed some time to eat and get a shower. He'd meet me at the shop in an hour. I drove back to the shop and waited again. Chris finally showed at 2:00 pm and announced that he had to be somewhere at 4:00pm. Damn. To his credit he worked until 7:00pm, but we were interrupted a bunch of times by "Mazda junkies" with their race tuned RX7's. They needed Chris to adjust the carbs etc. etc. It was nice to hear a 13B run, but unfortunately it wasnt mine. We had to cut a hole in the AL sump plate for the oil pickup. Next we had to take a run to the hardware store [which was closed - it was Sunday] for some bolts. Chris was thirsty, so we had to stop for a couple of beers. Well - it was Sunday after all. Eventually we assembled the sump and sump plate onto the engine. We didn't seal it because we didn't have all the bolts. By then it was 7pm. I explained to Chris how I need the engine, redrive and mount at my house so I can make the cowlings, so we loaded everything into my truck and I politely said goodbye. Chris agreed to come up to my house and do the work there later. Chris is basically a good and honest guy who knows his stuff. Unfortunately he's (always) very backed up with work and its hard to get his attention. On top of this he lives in the USA, but on Island Time. I needed to get control of the project, so now the engine will be configured at my house. If Chris can get up there to do it when I need it done - wonderful. If not, it'll get done anyway, and it'll get done under my supervision and in my time schedule. I may even end up learning enough to do it myself. The engine now sits, mounted on the false firewall and on it's stand next to the hot tub. A hell of a conversation piece.
I had planned on going NA (normally aspirated), but I liked Greg Richter's logic concerning using a turbo. It's a relatively simple way to quiet the exhaust and get rid of the heat. What I didn't like was the price of his Turbonetics unit. The trouble with the stock turbo for the 3rd generation 13B is that its a complex twin turbo setup which is quite heavy. During discussions with Paul Lamar on his ACRE website I found out that the single turbo on the '89 - '91 2nd gen engines was an excellent piece of work. It is relatively light and simple, has water cooled bearings, and it fits my '93 engine. Paul told me that he and a number of other builders are planning to use it. The Mechanair firewall forward engine from Switzerland is using it. I'm not sure if anyone is flying one yet. I decided to try and locate one. The bad thing is that they're fairly rare. I found one in "oz" at Japperformance for US $424 inc. shipping. The next day, Bulent called. He'd found one locally at a better price so I snapped it up.
That evening, while in the hot tub Char and I were looking at the engine and discussing the turbo. I decided to see if it would fit. This is probably the first time a 13B turbo has been assembled by a naked engineer. I slid the turbo onto the exhaust studs (two of which are missing). It fits beautifully. It barely misses the mount, but it does miss. Next I put the alternator in place and slid the redrive on. Hmmm. I got the starter and smog pump. This is starting to look like an engine. All I need is a few radiators and tubes and I'm done. Well, not quite - but I am starting to see some progress.