Mooney M20J air racing technique

[jetdriven]

My wife and I are planning to enter the Lone Star 150 air race this weekend in our 1977 201, and we are trying to determine what to do to prepare for the race, what to do to the plane beforehand, and looking for input as to flying technique.  There are 7 waypoints that must be passed between 500-1000 AGL.  Legs are about 15-30 miles. 

 

 So far, the cowl flaps were rerigged, we plan to fly WOT (no ram air on this plane) and around 1000 AGL.  I'd guess 180 MPH indicated is what it would do.

 

 

[DaV8or]

Take off your boarding step if you haven't already. Watch your engine monitor like a hawk.

[sleepingsquirrel]

Get some of Thinwings sub atomic dimpleling wax. Keep your feet off the rudder pedals,except in the event you need to take off or land.

[Shadrach]

 

Clean and wax it.

Remove step.

Only carry enough fuel for the race, plus reserves.

Strap a ballast weight in the rear most area of the baggage compartment. The goal is to be as light as possible with as far aft CG as possible. 

I'd run the engine WOT 50-60 LOP adjusting to maintain 380df or less. Do a test flight to see how the bird responds to RPM changes as you may not see a huge benefit from running at redline.

Alternately, you could run 250ROP and make adjustments from there.

80ROP is a poor idea... The power curve is so flat ROP that "the abuse to speed benefit ratio is minimal and at low altitude your CHTs will shoot through the roof at 80ROP at high power.  

Fly low, fly fast, and very importantly, fly as straight/direct as possible to each check point!

Good luck!! 

[sleepingsquirrel]

Cool your fuel with bags of ice around the fuel tubing from the tanks. Psych out your competitors by putting bags of ice on the wing to pre cool the fuel in the tanks. Hell ,just for fun bring in ten gallons of fuel that you have left in the freezer , be sure it is in insulated jackets and that your competition sees you pour it in just before the race! Don't tell them what you are doing, they will be so distracted trying to figure it out around the course they will  give up time.

[testwest]

Ross is correct. At that power you need to be either ~250 degF ROP or ~80 degF LOP to be out of the red box...the boundaries are actually a bit fuzzy.

JimR, you are correct that 80degF ROP is max power, but it is also in the dead center of the red box (no fuzz, there!) when above 90% power. At that power and mixture you may eventually build up enough heat in the cylinders to cause detonation. It certainly is hard on the engine....

Jetdriven, take a look at some of the past CAFE air race results...from the 1980s at

http://cafefoundation.org/v2/research_cafe400.php

You will find several M20J entries in the races, some flown by none other than Roy Lopresti. He tried the "near peak" ROP technique as published in the POH for best power, and suffered detonation pretty badly.

I would run WOT and ~250 ROP. Try to get the RPM down "some". Higher RPM is more power, you may be able to trail the cowl flaps, but you'll start to run into transonic losses at the prop tips. Lower RPM is less prop tip drag, but you start to push the peak pressure in the cylinder earlier in the piston downstroke, which increases engine stress and will give you higher CHTs, meaning more cowl flaps.

I would wax the wings, put a small amount of ballast (not too much) as far aft as possible to lessen trim drag. Go flight test your configuration before race day. Try WOT, 250 degF ROP, all air vents closed, 2700 RPM, see where the cowl flaps need to be to keep CHTs 380degF or so. Record the IAS, alt and OAT. Reduce to 2650, stabilize, determine cowl flap settings, record data. 2600, 2550, 2500. Compute your TAS for each condition post flight. Somewhere you'll find a sweet spot of max true speed as the drag from prop tips and cowl flaps optimizes.

Then, fly straight on the straight legs and roll into and out of the turns without huge control deflections.

Good luck and let us know how you do.

[Cruiser]

Fly the absolutely shortest distance possible. At your speed every one tenth (.1) of a mile is worth 2 seconds in time.

Remember distance is not only left/right but up/down as well. Watch for turbulence, climbing may cost you more than the extra speed you can get at altitude.

[sleepingsquirrel]

Now that your ballast is ice bags for cooling fuel and keeping the cabin temps under control with all the vents closed over. (Without breaking the rules or making the aircraft un-airworthy) Work on induction . Cool fuel needs more air, use the thinnest least restricitve air filter you can feel comfortable with. I suspect I would leave mine out if I wanted the ram air effect. A nice stainless screen will keep the June Bugs out and the little ones that get through would serve to seal off heat carb heat inlet to the induction box until needed.  At least shave the center portion of a foam filter as thin as possible .

 

[Shadrach]

Quote: testwest

Ross is mostly correct. At that power you need to be either 250 degF ROP or 80 degF LOP to be out of the red box.

JimR, you are correct that 80degF ROP is max power, but it is also in the dead center of the red box when above 90% power. At that power and mixture you may eventually build up enough heat in the cylinders to cause detonation. It certainly is hard on the engine....

[Skywarrior]

Quote: Shadrach

"CHTs will tell the story as OATs will not be warm enough to not mask what's going on in the combustion chamber..."

FIFY.

 

Chuck M.

[jetdriven]

Great ideas, guys. Keep them coming.  I did a test flight today with me only, full fuel (bigtime forward CG) and at full throttle, 2700 RPM, full rich and got 183 MPH IAS.  Which is something like 178 MPH CAS.   Interestingly the FF was 17 GPH and the CHT (cowl flaps closed) was 340 average.  I think it can be leaned more.

We just put in fine wire plugs and cleaned the injectors, our GAMI spread is .1 GPH.   So everything is well balanced. I think lean to 380 CHT will be the limiting factor.

We also removed the old LORAN antenna from the belly so that might be a couple MPH, and replaced an ACK ELT antenna with a Pointer unit, so there another MPH maybe.  Cinder blocks in the bag compartment to get a reasonable aft CG too, our elevator is deflected up a few degrees in cruise.  We have no step or ram air.  Cowl flaps rigged tight up against the cowl.  I figure 750-1000 feet altitude and smooth control deflections, bank angles of 45-60 degrees around turns.  Tape baggage door shut. keep scoop vent tight closed. Probably should tape it too.

 

@ Testwest, great idea about trying different RPM. We will do that.  Also with the configuration and mixture settings. What kind of WOT low altitude IAS do you get?

@ JimR.  good idea with the tiedown rings, CG, and antennas. Just removed one today.

here is the link to the race. http://lonestarairrally.blogspot.com/  We are "Team Chaos", as we are branded troublemakers around here.

 

[jetdriven]

Quote: sleepingsquirrel

Cool your fuel with bags of ice around the fuel tubing from the tanks. Psych out your competitors by putting bags of ice on the wing to pre cool the fuel in the tanks. Hell ,just for fun bring in ten gallons of fuel that you have left in the freezer , be sure it is in insulated jackets and that your competition sees you pour it in just before the race! Don't tell them what you are doing, they will be so distracted trying to figure it out around the course they will  give up time.

[Shadrach]

Quote: Skywarrior

Quote: Shadrach

"CHTs will tell the story as OATs will not be warm enough to not mask what's going on in the combustion chamber..."

FIFY.

 

Chuck M.

[testwest]

Quote: jetdriven

@ Testwest, great idea about trying different RPM. We will do that.  Also with the configuration and mixture settings. What kind of WOT low altitude IAS do you get?

[sleepingsquirrel]

Quote: jetdriven

I think I will bring xome jugs and pour the "special Nitro fuel blend" into the wings in front of them. Perhaps put some hazmat stickers on the cans.   That would be hilarious.

[Kwixdraw]

Have  a look at the leading edge of your prop. I would get a good prop man to take out any little defects and polish that baby(the leading edge, not the whole prop) bright with flitz and wax it too. Check your cooling baffles to make sure they are sealing as well as possible to minimize the need to trail the cowl flaps. You might want to check the prop balance and tracking if it hasn't been done in some time. Remember it's an airfoil too.

[Shadrach]

Quote: testwest

[Becca]

Quote: testwest

Good luck with the race and fly safe. You will have an absolute BLAST. As you can tell by the response to this thread, there are a bunch of us who wish we could be racing there as well. Make us proud and be sure to beat those Bonan(z)as while burning 50% less gas.

[N33GG]

I like to watch the Red Bull races with the cameras in the cockpit.  It is very interesting to see what makes the difference between winning and losing.  These guys are squeezing out tenths of seconds.

Aircraft smooth, slick, light, low drag, and aft cg...check.  As much hp as you dare push throughout the race...check (after all, it's your engine, you can do whatever you want!).

Now for the biggest issue... your flying.  As previous posts have stated, smooth in and out of turns to reduce induced drag.  From watching the Red Bull races, the biggest killer of time is any unnecessary up and down variation in altitude, especially in turns. (Again, as mentioned in a previous post.)  As much time and effort you are spending getting your plane ready, be sure to spend twice as much time getting your flying technique up to the task.

Good luck!

[Bennett]

Back in the early 1990s I raced my Mooney 261 (my Mooney at that time) in the Sun and Fun 60 Mile sprint, and managed to win our class, and then the next week raced her in the Columbus 500 from Freeport, Bahamas to Provo, British West Indies, with a dog leg at Stella Maris.  We won that race, but only by a half fuselage length over a Malibu.  This was 500 miles of WOT racing, with about 40 aircraft competing. It was just plain fun.  My advice: Like so many others - keep her as light as possible with aft CG, minimum fuel (with a reasonable reserve), polish everything - drag is your enemy.  Make sure the gear doors are actually tight when the gear is retracted, likewise the cowl flaps, and anything that could hang down. Check aileron and flap seals if you have them, and consider taping over the cockpit vents. At one time LASAR had tail-cone seals, and perhaps they still do.  I had them for the 261. The advice about the prop is right on. Full power however you can get it without letting CHTs get over 375 degrees, and watch oil temperature to keep under 200 degrees.   If possible make a trial run to calculate fuel flows, (deciding on fuel load), best altitudes for TAS, time to climb, etc., play with prop settings, as 2700 RPM might not be optimum, study winds aloft direction and speed predictions, and above all, fly as smoothly as you can with the ball centered at all times.  Have fun, and best of luck.

[Amelia]

Quote: Becca

We're hoping to learn a lot, because I'd like to fly the Women's Air Race Classic next year in this plane.  Need a co-pilot though, any takers out there?

[DaV8or]

Quote: JimR

[DaV8or]

I only use mine above 5000 ft, but I don't have a real 201 cowl, so it does boost at least one full inch, sometimes a tiny bit more. For me, it's free performance.

[testwest]

So, here are the results from jetdriven, called "Team Chaos" in the race!

RACE 201     TEAM CHAOS     MOONEY 201    FAC3RG       57 MIN 26 SEC    152.2 MPH       132.26 KTS

Interesting....any comments from the racers?

[sleepingsquirrel]

The other purpose for the ICE for ballast and keeping the fuel cool and moving the center of gravity aft is:

The BEER in the baggage compartment would be just right for the after race festivities! Win ,lose , or draw

Nobody likes a conceited winner,or  a sore loser, but everyone likes the guy with the coldest beer!