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RV-8 13B Turbo Rotary makes second flight

SHIPCHIEF

Well Known Member
Today I made out my second test card. The simple second flight to assess controlability and let the engine run.
I climbed to 1000 ft. above the pattern, accelerated to 160+ MPH, then reduced power to 120+ MPH. Total flight about 30 minutes of pure bliss.
I'm running a Mazda 13B Turbo engine, approximately a 1988 model. I'm burning 92 Octane ethanol free unleaded Mogas.
Power passes thru a Tracy Crook RD-1A 2.19:1 reduction gear with left turning Catto propeller. The only flight adjustments were mixture to observe and reduce exhaust temp, and the pitch trim knob. (Oh, and 1/2 flaps for the landing) This is such an easy plane to fly.
I've posted here about some of my pre-flight engine tribulations and developement leading up to the first flight.
Now I can reap the rewards of all that work. The RV-8 is a dream plane. I have a Thorp T-18, which I have enjoyed tremendously, but I always kept working toward the RV-8 13BT. To those of you building: Keep at it, the feeling of satisfaction is deep and lasting!
Ross, thanks for the help sizing the Turbo, the engine behaves very well now. I plan to eventually add an intercooler as many have advised, but as of today, the take-off performance is equal to or better than an O-360 w/ fixed pitch prop, so the basic requirement has been met.
Temperatures & pressures all stayed in 'the green'. The next flight will follow another under cowl inspection, but right now, no changes are anticipated.
To those requesting video of the first flight; it's pretty shakey, and some of the side bar conversations about neighbors with long propellers might not be appropriate. :rolleyes: However, 89SE is actually pretty quiet.
 
Congrats Scott on getting the project flying. Good luck with the flight testing, and the powerplant installation.

I thought long and hard about a Mazda engine before I started my RV-8, but eventually took the more travelled road of a Lycoming. It is good to see people trying alternative engines, as long as they have a good understanding of the extra work involved and the additional risks.

I?m looking forward to reading some performance numbers once you have determined those, and your weight and CG. What prop do you have?

Fly safe. Have fun.
 
Scott, Excellent news. I have always followed your progress reports closely and have admired your reasoned approaches to problem solving. I really hope for continued success for your experiment, and continued satisfaction from it.
 
Congrats Scott, nice to see a positive report! Looking forward to more numbers when you get them.:)
 
Today was a beautiful cold blue sky day. After an engine compartment inspection, and a couple of drop-in conversationalists, I got a 30 minute flight in. I burned about 3 gallons of (for Bill H) Union 76 92 RON+M/2 ethanol free Mogas with 1 Oz/gallon 2 stroke oil for the tip seals.
I don't have data logging, so I need to get a GoPro camera or such, and mount it so the panel can be observed, along with a flight view.
I set take off power to about 34" Hg manifold pressure which yeilded about 5050 Engine RPM, 2306 Prop RPM. We climbed out from 470' field elevation to just under the 5000' Class B floor. I tried to maintain 100 MPH indicated airspeed, and the sustained climb rate was 'about' 1500 fpm I really didn't spend much time watching it. The initial throttle and mixture settings were retained during this climb. The mainfold pressure dropped to about 28" Hg at the top, and the oil temp just arrived a 200 F at the top as well. Today the shaded areas near the hangars never thawed, so I presume the OAT was below freezing at 4970'MSL.
The jacket water temp at the top was about 156 F, good, but oil cooling might be a problem as the weather warms. I'll try climbing at 120 IAS next time.
I followed the usual procedure of some climbs and glides, 20, 30, 45 bank angle turns, and initial stalls clean, 1/2 and full flaps. Clean stall is just a mush, but with 1/2 and full flaps at the 1500 Prop RPM power setting gave me a little warning and a break to the right. Maybe I need more left rudder. This left turning prop thing, I'm getting used to it...eventually.
The Tracy Crook Engine Control Unit mixture control is very powerful, maybe +/- 15%, so this was explored during decents & a simulated landing approach.
I came over the numbers a little slow on landing and dropped in just enough to feel the RV-8 leaf spring gear work, kind of a levering back into the air feel, very different than an RV-4 or my Thorp T-18.
Right now, the whole powerplant assembly seems very reliable and operable, but I'll be the first to admit that I'm treating it with 'kid gloves'. I cannot fully advance the throttle for fear of exceeding the maximum mainfold pressure design limit of the Engine control unit. Also I'm a big chicken ;)
Kevin H, I shamelessly copied and ammended your checklists and use your V speed data as an initial guide. Thank you. I'll have to get back to you on the W&B & prop data, I'm not at the plane + Documentation, but it's Empty Weight is very close to 1100, CG is about 1/3 back from the forward limit at the full fuel test flight condition so flight weight must be about 1590 lbs with gas, me, some resources and a fire extinguisher. The prop is a 2 blade Catto, I think 68x74, (not sure) Craig and I decided to have him make it a left hand version of the same prop he was making at the time for an RV-8 with an O-360 180 HP engine. It makes for an interesting comparison to an O-360 powered RV-8, the closest this engine will ever get to a Dynomometer.
 
I cannot fully advance the throttle for fear of exceeding the maximum mainfold pressure design limit of the Engine control unit.
If I understand correctly, you'll need to be very careful if you ever do an unplanned go-around from a landing approach. It might be wise to craft some sort of spring loaded throttle stop. The basic idea is that the throttle stop would stop the throttle at a position that was guaranteed to be within the MP limits, but still give more than enough MP for good go-around performance. So, you could push to the stop without concern, then when you have a spare moment you push the stop out of the way and gently advance the throttle to the desired MP. The stop would automatically go back into position when you retarded the throttle.
 
Correct, no waste gate. Keeping the weight down is a never ending challenge.
I'm trying to achieve a nice balance of parts to minimise the number of sub-systems. I have a light blow off valve that should attenuate boost gains above 38"Hg.
I flew it again today for 30 minutes, I got 2 crumby iPhone pics to capture data in a stable modest power cruise:
5000'MSL, 7C OAT.
5157 RPM (2355 Prop RPM), 23.7" Hg, 161 MPH TAS according to EM-3 data
Water temp 169F, Oil Temp 193F, EGT 1734F
No gear fairings yet.
I briefly saw 191 MPH when I let the nose down to return to the pattern. Slippery airframe!
The mechanical Turbo charger discharge pressure gauge is from a twin. during this moment it indicated 36" before the throttle, 24" after the throttle ie; the manifold pressure. This indicates a 12" Hg pressure drop across the throttle, or approx 6 PSI. However, compared to 30.04", today's atmospheric pressure, 36" is about 3PSI, a modest boost. I am rationalising that this is a very acceptable condition for a common cruise setting.
 
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