[Ron Lee]

Assume speed of about 200 MPH. Have to cross a point then turn 120 degrees to the next turn point.

Is there an optimal bank angle?

Slow down then turn?

 

[Bob Axsom]

There probably is

Ron,

There probably is but I don't know the optimum bank angle. Since there are only two significant turns within the Memphis 100 after the start it will not be a major factor even if they are pretty sloppy. You certainly do not want to slow down either by intentionally throttling back or standing it on a wing a turning with your elevators. Coming to the turn a little wide so you can keep your speed up through the turn may not be a bad idea. Be careful not to cut inside the turn point as the penalties are severe as I recall.

I'll be watching you from behind I'm sure. Your speed will be higher down at 500 to 1,000 feet (I don't know what the race floor will be) than the 197 you saw at 8,000 ft.

By the way, they start in speed order to avoid in race passes so if you see more than one pass from your cockpit in the entire course that will be unusual.

Good luck.

Bob Axsom, Race 71 "Blue Bird"

 

[edneff]

I'm not an expert on this topic, but wouldn't you want to do a 90 degree bank, or something close to it? Pass the turnpoint and bend it around as hard as you can, and then point it direct to the next turpoint without correcting back to the straight line A-B.

 

[Kyle Boatright]

Years ago, Van wrote about his turn strategy in the Sun 100. His strategy was to fly a constant radius turn at a fairly relaxed G loading. I'm sure the G's were under 3, but I have not gone back through the stack of moldy RVators to verify the memory.

Is your aircraft FP or C/S? I would think a C/S airplane's optimum G might be a little higher than a FP aircraft, simply because the C/S airplane can generate full power all the way through the turn, wheras a FP airplane loses rev's and HP if it slows down.

 

[mark manda]

or do you bank hard and pull up and use the smash to get you up to favorable winds faster?

 

[Ron Lee]

Mine is a FP prop.

It probably does not matter anyway since I will be bucking Bob's turbulence anyway.

 

[groucho]

How long are the legs?

Just some quick math...given a constant 200mph TAS, here are the g levels, bank, the corresponding turn radius & time to turn 120deg:

2.0g, 60deg, 1552ft, 11.1sec
2.4g, 65deg, 1254ft, 8.9sec
2.9g, 70deg, 979ft, 7.0sec
3.9g, 75deg, 721ft, 5.1sec
5.7g, 80deg, 475ft, 3.4sec

If it were me, I'd do some turns through 120deg of heading at 2, 3 & 4g & see how much speed you lose on each. At the end of those, fly exactly level & see how long it takes to accelerate back out to 200. From there, you'd have to do some more math to figure out what gets you to the next turnpoint the quickest.

As long as the legs are long, your turn radius won't matter as much as how long it takes from the start of your turn until you're back at full speed on the new course (they're really connected, but my point is don't pick based on turn radius alone). Without any flight test on it & just guessing based on my 6's performance, I'd say pull about 3g's & forget about it.

HOWEVER, turns are certainly an important part of the race. A second lost in a turn can be the difference between winning or losing. I was in an EZ race about 10 years ago where two of the racers finished within a plane length of each other after over 100nm of flying. I say go do some flight test & figure it out to the gnat's a$$.

Edit: slowing down to turn won't help.

More Edit: This is blasphemy, but an autopilot tracking a GPS great circle direct-to route can save a bunch of time. My A/P is good to hold me within 0.02nm of course (120ft). That's way better than I can hand fly it.

 

[dan]

How about a half lazy 8 style turn? You'd exit the turn at the same altitude & airspeed at which you entered it, and you'd seriously "cut the corner." Just a thought from a NON EXPERT.

 

[az_gila]

45 degrees

In glider flying I was taught that the lowest loss turn was a 45 degree banked turn.

This sort of fits in with Vans lowish G, constant radius turn.

You will have to anticipate the start of the turn and the offset from a straight line to the exact turn point. You want the apex of the curve to be "just" outside the precise turn-point co-ordinates. With the new GPS systems and a bit of mathematics, this should be relatively easy to calculate...

Aerobatic maneuvers that involve changes of height might be considered a safety hazard if other competitors are nearby...

gil A

 

[rv969wf]

Go to RENO

Anyone needing advise, go to the RENO air races and watch the PRO'S.... I went this year and when they flew,,,, they were taking large radius turns around the pilons and keeping there elevation the same. Most of the pilots were not banked more than 35-55 degrees. Take this for what its worth. Been there, seen it, etc.

 

[dan]

Yeah, but what's the biggest heading change they have to accomplish on a turn?

The original question asked about the optimum way to produce a 120 degree change in heading.

I've been thinking more about this and I stand by my "lazy 4" analogy. Anything more than about 120 degrees and I'd be looking at that 3rd dimension VERY seriously. Go out and test it. I plan to.

 

[Chappyd]

This may or may not be relative. I used to race model planes. Little F-1 models that went 200 mph, had about 3 hp and turned props at about 25,000 rpm. Smoother is faster. Yank and banks will slow your airplane. Any control surface deflection creates drag.

From a minature perspective, but physics are physics.

 

[dan]

physics are physics.

Yep, they sure is.

Think about it. If you just bank hard and then haul on the Gs, as others have noted you would end up exiting the turn having bled off some of your energy. Now you're going to WASTE precious time accelerating back up to full straight & level max speed. As we all know, that last few% of the speed band takes the longest amount of time to achieve.

So DON'T GIVE AWAY that last bit of speed.

If you add vertical to the mix, yes, you will slow down in the process, but you EXIT at the SAME airspeed you entered. NO TIME WASTED. Yes, you slowed down during the maneuver, but you change heading JUST AS QUICKLY and you don't sacrifice one bit of the top end speed on exit. I'm not talking about going straight up. I'm not talking about abrupt maneuvering. I'm just talking about adding a dimension to the maneuver on sharp heading changes.

Am I the only one smoking this crack pipe?!

Groucho, Kahuna, somebody out there who understands a HI YO-YO in the context of energy management, chime in.

 

[RV6_flyer]

How about a half lazy 8 style turn? You'd exit the turn at the same altitude & airspeed at which you entered it, and you'd seriously "cut the corner." Just a thought from a NON EXPERT.

When I raced my RV at Mesquite several years ago, (it may have been back in the 20th century) they did not allow us to change altitude in the turn. I wanted to do what you say but they would disqualify you if you did.

 

[Nuisance]

If you look at the Reno diagram Sharpie posted, the red lines are the "deadlines". The penalty for cutting a pylon is a few seconds, but if you cross the deadline you are DQ'd. So, the near 90 degree angles you see at Reno are required by the course and the speeds.

In the late 1920s Jimmy Doolittle developed a technique where he would fairly gradually climb before the corner, then dive as he went through the corner to take some of the g-load off the plane and keep the speed up into the next straightaway. Soon all the racers were doing it.

The altitude change is not illegal in our racing, but it does increase the possibility of a mid-air. Mostly we are racing single-file, but if someone doesn't give his correct speed to the race boss then some passing may happen. So it is important to have your head on a swivel.

My technique has been to fly a line that is about 1/2 mile outside of the direct point-to-point course. Then I can hold a 45 degree turn and cross over the turn spot, and hopefully not lose too much speed, and not travel too much extra distance.

Good luck, John

 

[Kahuna]

Yep, they sure is.

Think about it. If you just bank hard and then haul on the Gs, as others have noted you would end up exiting the turn having bled off some of your energy. Now you're going to WASTE precious time accelerating back up to full straight & level max speed. As we all know, that last few% of the speed band takes the longest amount of time to achieve.

So DON'T GIVE AWAY that last bit of speed.

If you add vertical to the mix, yes, you will slow down in the process, but you EXIT at the SAME airspeed you entered. NO TIME WASTED. Yes, you slowed down during the maneuver, but you change heading JUST AS QUICKLY and you don't sacrifice one bit of the top end speed on exit. I'm not talking about going straight up. I'm not talking about abrupt maneuvering. I'm just talking about adding a dimension to the maneuver on sharp heading changes.

Am I the only one smoking this crack pipe?!

Groucho, Kahuna, somebody out there who understands a HI YO-YO in the context of energy management, chime in.

G is a turn speed killer. Unlike a power boat which can jump back to speed in an instant, our medium takes too long.

As for using the vertical, while you might enter and exit at the same speed, you will not have covered the same distance due to g, angle of attack drag, and so forth. Since a race is about distance to target, forget the vertical for the turn.

Vertical in the yo yo is about displacement into another plane(dimentional plane) and gaining an advantage of position, timing, and sight picture against a target. Used to fix a potential overshoot by decreasing closure rates and gain advantage out of plane. Too complicate for me to type.

Also I do not think the formulas are useful because if you look at the factors affecting entry and exit speeds for a turn, weight, power, prop, and other factors play big in this game. I do not have a clue what the answer is, but I suspect gentle is better than yank.

my 2 cents,

 

[Christopher Murphy]

race turns

Anyone needing advise, go to the RENO air races and watch the PRO'S.... I went this year and when they flew,,,, they were taking large radius turns around the pilons and keeping there elevation the same. Most of the pilots were not banked more than 30-40 degrees. Take this for what its worth. Been there, seen it, etc.

The above technique is the best I have found. Keep the rpms up and make a nice smooth turn around the pylon. The most critical point is to make sure you roll out on the correct course to the next turn. You will loose much time if you have to bracket the direct course. When your plane is totally stock, no aftermarket plenum,wing tips,cowling,etc one must use every trick in the book to go fast. Precise flying will make up for some of these handicaps.

RACE 34 ( still working to get to MEM 100)

 

[groucho]

So DON'T GIVE AWAY that last bit of speed.

Groucho, Kahuna, somebody out there who understands a HI YO-YO in the context of energy management, chime in.

A Yo-Yo/whifferdill is certainly one way to get your turn rate up, but like Kahuna said, there are many other variables you throw in there too. I can't say for sure which way would be faster, but, IMHO, I think you could get within a second of the no-kidding fastest race turn by just varying g to figure out what gets you pointed the right way & at full speed the fastest.

The math does matter in this, but only once you start to get close to the best solution. A good technique was mentioned...offset pylon by whatever your turn radius is (plus a margin so you don't cut it), then pull however many g's through the turn you planned on (2, 3, whatever).

Over a cross country race, there are many, many other things that can matter more. If you start on the runway & have to climb to altitude, what climb airspeed to you use? If the finish line is back at runway level, when do you start decending? What altitude do you fly? Lots of other things to think about too.

FWIW, I sat at Pylon 1 during an unlimited race in 2006 & they were probably close to 70 deg/bank...which matches the 500mph spec on the course layout. Cross country races are different than Reno though...tons more time in the straights.

Alright, where's the next race near SoCal? I'm in.

 

[Ron Lee]

Memphis 100 race course

~ 100 nm, Relatively equal legs. The start is while airborne.

Details here: http://www.sportairrace.org/id132.html

Since this will be my first race, I am clueless about many things. I am assuming that they want you to fly right over the turn point for timing purposes. If not, then being a bit outside during a turn like John does won't matter.

I know that I won't be first. Maybe not even second or third. But I need to beat the person whose posts motivated me to enter the race.

 

[az_gila]

Offset your track...

......
My technique has been to fly a line that is about 1/2 mile outside of the direct point-to-point course. Then I can hold a 45 degree turn and cross over the turn spot, and hopefully not lose too much speed, and not travel too much extra distance.

Good luck, John

Hey... that's what I said earlier....... but John put it better describing the offset in your course to the actual turn point.

I think some of the previous posters assumptions are that a ground track is required with a "sharp" corner of the 120 degrees at the turn point...

A smooth turn with minimum losses and low control deflections will win....

gil A

 

[dan]

As for using the vertical, while you might enter and exit at the same speed, you will not have covered the same distance due to g, angle of attack drag, and so forth. Since a race is about distance to target, forget the vertical for the turn.

I thought a race was about TIME to target. I would argue that covering less distance in your turn is a very good thing, especially if it takes less time to do so.

Previously somebody mentioned "slowing down for the turn," which I think we all agree is bad due to the lack of acceleration in general at the top end. But if you can "virtually" slow down without losing speed on exit, all the better.

 

[dan]

A smooth turn with minimum losses and low control deflections will win....

Not in all cases.

Only way to settle this...let's go out and side-by-side it, lock the power in so we're sync'd speed-wise in straight&level, and see who comes out ahead after the turn. I'll turn right up against the pylon and you'll go wide. By the time you roll out on heading and wait to accelerate that last little bit again, I'll already be there, on the inside track, full speed.

 

[Kahuna]

I thought a race was about TIME to target. I would argue that covering less distance in your turn is a very good thing, especially if it takes less time to do so.

Previously somebody mentioned "slowing down for the turn," which I think we all agree is bad due to the lack of acceleration in general at the top end. But if you can "virtually" slow down without losing speed on exit, all the better.

To clarify, a climbing turn yo yo will cover a lesser distance per given amount of time than a level turn, although your exit and entry speeds might be the same. Since the race is time vs distance, using vertical would be bad. I can not explain why Doolittles plan worked.

 

[az_gila]

I concede....

Not in all cases.

Only way to settle this...let's go out and side-by-side it, lock the power in so we're sync'd speed-wise in straight&level, and see who comes out ahead after the turn. I'll turn right up against the pylon and you'll go wide. By the time you roll out on heading and wait to accelerate that last little bit again, I'll already be there, on the inside track, full speed.

OK ... I concede... your RV-7 will beat my Tiger....

gil A

 

[gmcjetpilot]

Good advice

Assume speed of about 200 MPH. Have to cross a point then turn 120 degrees to the next turn point. Is there an optimal bank angle? Slow down then turn?

You already got good advice. However the "slow down" part is not necessary, turning normally slows you down plenty. If you ever want to slow down, a steep high G turn will do it. That is the basis of the 360 overhead military arrival. Each plane flies over a spot, say end of runway and does a descending high G turn to final, slowing drastically while lowering gear and flaps.

If your POINT its a repeated turn or part of a course, taking it wider, with lower G's is usually best, verses flying just next/over the point and pulling harder to make the next gate/point. As per my acro advice, try to stay under 3g's as a max if at all possible.

If its a one time deal, say for example like a dive to the last or finish point, like baseball, over running first base, just go for the finish line/point and than make the turn.

 

[groucho]

Only way to settle this...let's go out and side-by-side it...

Yup. Flight test. Some RV's will be higher drag than others though. So even if they are matched at a given airspeed it doesn't necessarily mean equal drag profiles once you change the speed.

If you really want to know, record your flight (EFIS, GPS, whatever) and compare the results of different techiques. Once you know the answer, share an incorrect answer with the rest of the guys you are racing.

 

[RV8N]

In the late 1920s Jimmy Doolittle developed a technique where he would fairly gradually climb before the corner, then dive as he went through the corner to take some of the g-load off the plane and keep the speed up into the next straightaway. Soon all the racers were doing it.

According to Jimmy Doolittle's book, he made those wide, flat turns because the GeeBee R2 was almost uncontrollable. He is the only one to fly one of the originals and walk away from it. He was scared to death of it...

Of course it didn't hurt that he was way faster than everything else on the course and could afford to turn that flat and wide.

Karl

 

[gmcjetpilot]

Red Bull Air Race Video

If you watch the RED BULL air races on FSN you will see the affect of turns both in the horizontal and vertical.

If not familiar here is their site: http://www.redbullairrace.com/

The cool part is the "Dartfish" (sp?) video replay, shown after a heat between two planes. The planes fly the course separately for time, but after the heat the dartfish superimposes the images of each seamlessly into one. The times can vary by fractions of a second. The video shows where or how one pilot gained or losses on the other plane.

Because the course has turns in the vertical and horizontal its fascinating. BTW these guys are nuts and excellent pilots, but flying so low and fast is just amazing.

 

[Bob Axsom]

One Other Thing - Visibility

This race is being flown with all right turns and the turn altitude is fairly high. Our friends in RV-3s, RV-4s and RV-8s will ask "So what?" Well if you are close in to the turn point at several hundred feet of altitude in an RV-6, RV-7, etc. you will never see the turn point from the left seat. You will have to pick a reference that is off to the side to know that you have completed the previous leg before turning to the new one. Since the race leg ends at a fly-over point it might be safest as far as completing the course is concerned to fly directly to the point and begin the turn as soon as you see your offset reference pass by. If you do this you want to hit the Direct To button on your GPS after the turn for the next turn point or finish rather than make a teardrop back to the point to point course line. The photos in the race package are good enough to allow you to pick out a visual turn point offset reference.

Bob Axsom

 

[Bob Axsom]

Well Done Ron

It was good to meet you and now you can tell others how to go about it. Good job on the race course.

Bob Axsom

 

[bswat]

Red Bull race pilots pull heavy Gs

The earlier post on watching the Red Bull racers is right on. If you watch them race, you will see that they regularly pull 9.5+ Gs in horizontal and vertical turns. They do horizontal turns banked at nearly 90 degrees and the comparison of racers almost always shows the tighter turn as the faster airplane. A 30 degree bank at ~250 mph would take the airplane out of the Red Bull race course.

Bill Swatling
RV-7 fuselage center section almost ready to join the tail cone

 

[groucho]

Just one note...the Red Bull guys are required to go through some gates horizontally & some vertically. The course is set up so that you have to pull lots of g's to make it through. On a long cross-country race, I doubt a max-g turn in an RV would be the best way to get there fast.

Still, it's worth trying a couple techniques & seeing what's the fastest. Turn your GPS on record mode & see what you can come up with.

Have fun,

 

[N941WR]

The secrete to going fast is?

never slowing down.

That is the mantra we used in auto racing anyway. You will have to tell me if it applies to airplanes.

 

[TOAD]

Never slow down is right.

I do not know if it applies is correct but... I have sailed hundreds, thousands? of sailboat races. Several things have been said that you can not ignore. It is most important to not get lost. Know exactly where you are and where you want to go. That means entry to the mark and knowing exactly where it is and where you want end up on the exit. Unlike racing cars with bales of hay and tires, you will need reference points some where way out there... to line up on. Look first before starting a turn or have a copilot visually site the 120 degree turn before you start. Take a line like before starting an aerobatic maneuver. Fly the course first if you can. Look for the church steeple to line up on exit. You wish you could be so lucky! Don't get lost for even a second.

The fastest way to know what is fast for your plane is to have a second plane to test against, a trial horse. Like in the Red-Bull stuff the only way they see where the time was made. The super imposing images tell the story. There was not much difference... Just enough to win or come in second. Look at the small entry-exit differences. That was what the pilot thought was fast. He could have flown it differently just ask him. It is my experience also that you can not beat testing. How to be fast is learned and different for each craft. Each plane will have an optimum way it flies based on HP, Drag, Time to recover to full speed etc. I have had some experiences trying to make my Citabria go as fast as it can. I would bet that what works there are about worthless for our RVs. Be careful what advice you take. It may be good but not applicable for your plane.

Gotta get the RV flying!!!

 

[mike newall]

Smoothness always wins.

Years ago, I did the Schneider Cup on a couple of years in a Piper Lance - 186 mph declared speed - handicap air races in the UK.

Don't pull more than 3 g - wastes energy.

Smooth roll in, roll out and push always seemed to work well.

If it's a flat out race, it will be won on the navigation, if it's handicap racing, calculate your declared speed and don't bust it

 

[N916K]

I would think that with a data logging GPS and Google Earth you could do some very nice back to back comparisons. Also may help practicing simulated race corners instead of waiting for the race to figure it out.

If anyone in SoCal wants to use a bit more advanced IMU to record data let me know and we can set something up. Maybe I'll even run some tests once I get my 9 back in the air.

 

[N98HK]

Constant airspeed, maximum g...and all 3 dimensions.

Sliceback - if constant altitude is not required.
Firewall the power (if its not already there).
120 deg of bank, and g as required to maintain a constant airspeed. You'll have less than 1000' of altitude loss, and you will use the 1g that god provides to help change the direction of your aircraft.
Two things need to be taken into account when turning your aircraft:
1. Turn radius.
2. Rate of turn.
Both will change depending on if your are sustaining energy (constant airspeed) or depleting energy (increasing g and decreasing airspeed). You will turn around quicker if you keep the aircraft's kinetic energy high, and sacrifice some potential energy (altitude).
If you fly a 30 deg bank turn and do so for 120 deg of turn, you will get left behind by the aircraft that smartly sacrifices some altitude to turn inside.
Some flight test and a rate/radius diagram at the expected altitude will deliver the most accurate answer. There is a balance between sacrificing some airspeed to turn a little quicker, but then you also have to take into account acceleration rates. An RV will go from 160 to 190 pretty quickly, but getting on top of the air and cruising above 200 takes a little time. The answer is flight test to find what works for your aircraft. Too many variables to provide the perfect answer, but the 90% solution is to hold constant airspeed and sliceback.
If the turn was 180 deg, a split S would get you going the other way in the least amount of time. You get a free g through the first 90 deg of turn!

I ramble...on and on...and none of this matters if you can't change altitude.

 

[Bob Axsom]

Question Ron

I am gettineg ready for the Rocket 100 on the 17th. Seriously, did you learn anything I should know about turns in the race (this one has a 150+ degree turn)?

Bob Axsom

 

[Ron Lee]

Turns

Bob,

I did so many things wrong that the turns were the least of my concerns.

 

[penguin]

All airplanes are not equal in turns

A low aspect ratio parallel chord wing, as all RVs have, is meant to be slow & draggy (that's why gliders have long high aspect ratio wings), but if you run it at very low angle of attack (as we do at cruise, and even more so in a race) it doesn't matter as the induced drag is very low. While you might get away with tight, high g turns in an airplane built for turning (Red Bull racers) on a course that demands you fly exactly where the organizers specify, in an x-c air race in an RV its different. If you load up an RV wing to 4 or 5g the induced drag will go way up, and your speed way down. I would have thought 60 deg AOB/ 2g would be the max for any kind of significant turn? I don't have any data, so this is all speculation. If you can select your own course wide in & out and gentle turns would seem to me to be best? How about collecting some data? How long does it take to turn 90 deg at various bank angles from max speed, and what is the speed lost?

Pete