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Author Topic: Lap times  (Read 3085 times)

Offline Paul Taylor

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Lap times
« on: September 24, 2016, 08:51:39 AM »
I just read something in SN that led me to think that a guy that flys faster has a better chance of winning the NATs.
(Or any contest?)

Is a 5.0 better then a 5.5 lap time. Or is the just to the windy conditions at the NATs?
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Offline Tim Wescott

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Re: Lap times
« Reply #1 on: September 24, 2016, 10:37:52 AM »
If someone who actually wins the Nats contradicts me, listen to them.

Based on my own experience, and what I read here, 5.0 second laps are a bit fast to be competitive, and 5.4 or 5.5 second laps are a bit too slow.  Somewhere in the middle is a nice compromise.  I know from personal experience that when you get to, or even past, the slow end of that scale you can get some really beautiful flights in -- as long as the wind is just right.  Flying faster makes the plane less susceptible to wind, as you point out, but 5.0 laps gets a bit rushed.

The really good pilots, AFAIK, goose the speed a bit in high wind conditions.  But even though I fly under-expert, I'm not good enough to do that reliably.
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Online Brett Buck

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Re: Lap times
« Reply #2 on: September 24, 2016, 10:43:54 AM »
I just read something in SN that led me to think that a guy that flys faster has a better chance of winning the NATs.
(Or any contest?)

Is a 5.0 better then a 5.5 lap time. Or is the just to the windy conditions at the NATs?

   Not really. You run the speed you need to run to get the performance you want. If you get too slow, you can lose the ability to just sit back and steer it around and you have to help the airplane by whipping, etc, But as long as you have sufficient tension everywhere, more doesn't help, and tends to hurt. For a reference, at last year's Golden State contest, we had about 15-20 mph sustained and smooth as silk, and I think someone got me at around 5.4 seconds, from a baseline around 5.25-5.3.

   Also, in general, you can fly slower when it is windy.. The wind can help you, almost too much at times. Crank the needle in in a 20 mph wind and your airplane is going to pull you over or pull the wings off. You need some speed in dead air to make up for the lack of assistance, and to barrel through your own turbulence.

    I end up flying slightly slower at Muncie than I do here in California. Instead of 5.25-5.30, I am usually around 5.4 in Muncie depending on the conditions. For whatever reason, I get slightly more tension for a given speed in Muncie, in all conditions, wind, calm, etc. But I don't target a speed. I just adjust the needle until it feels right to me, adjust faster in calm, and a bit slower in smooth heavy wind, and it usually works out.    How your engine responds to needling also makes a big difference. An ideal setup will get more aggressive if you back off on the needle, with more boost/brake as you slow it down. This is also very helpful in the wind, so you can have more power when you need it, and less power or more braking action when you get whipped up.

    Muncie is not at all bad for wind compared to many places we fly. Try going out at 2:30-3:00 in the afternoon at Whittier Narrows, or Napa. The only difference with Muncie is that you have to fly when it's time to fly regardless of the wind. Every place else, you just decide to skip it when its bad. It is absolutely no accident that the two most successful competitors both spent some of their formative years flying in very difficult sites (Paul Walker at Whitter Narrows and David Fitzgerald at one or the other of the Napa sites). Even David gives up about 11:30-noon at Napa.


      Brett

Offline Tim Wescott

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Re: Lap times
« Reply #3 on: September 24, 2016, 11:17:35 AM »
If someone who actually wins the Nats contradicts me, listen to them.

(Brett counts for this).
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Offline Steve Helmick

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Re: Lap times
« Reply #4 on: September 24, 2016, 03:35:07 PM »
Didn't Paul once say that since you need to fly faster in turbulent conditions, that you should fly fast all the time, so that  you'll be used to the speed? Probably doesn't mean that he wouldn't slow it down if given the opportunity. Maybe he meant to practise flying fast, so that you'll have a better feel for the plane when you are required to fly fast?

My plane has to fly fast because it's a porker. This doesn't help me at all, but it'd scare me to find out what the lap times are, so I don't bother to check. Probably somewhere under 5.0 sec., tho. If somebody times it, please don't tell me!  n1 Steve   
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Offline Howard Rush

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Re: Lap times
« Reply #5 on: September 24, 2016, 04:28:49 PM »
Doug Moon, who won the Nats, putts along at about 5.6 seconds per lap.
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Offline john e. holliday

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Re: Lap times
« Reply #6 on: September 25, 2016, 03:53:14 PM »
Doesn't the line length have a lot to do also?    I don't believe every one flies the same length and diameter lines.  I see also where some guys say they launch at a certain RPM.   
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Online Brett Buck

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Re: Lap times
« Reply #7 on: September 25, 2016, 04:03:15 PM »
Doesn't the line length have a lot to do also?    I don't believe every one flies the same length and diameter lines.  I see also where some guys say they launch at a certain RPM.   

   Yes, which is why you don't pick a lap time. You adjust it until it feels right, then measure it as a relative number. If you later make a trim change, then you can know whether what you felt is because of the change you made, or just a matter of faster or slower settings.

    Lots of people "launch at a certain RPM" - so that they can either repeat the same feel, or to be able to adjust it up or down depending on the conditions. So, again, it is relative to what you felt the last time. It is a big mistake to screw the needle in and out to hit a particular RPM unless you base it on something. I will adjust about 25% on the measured RPM, about 25% on the sound, and 25% on the way it felt the last time I flew it in similar conditions, and 25% with relative needle movement.

     Brett

Offline Steve Helmick

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Re: Lap times
« Reply #8 on: September 26, 2016, 06:39:04 PM »
Was launching for an unnamed flier this Sunday. Uniflow, tachometer, etc. Every time he reached for the NV, the engine leaned out, because his hand was blocking the prop blast into the uniflow vent. It went like this: Adjust, tach, adjust, tach, adjust, tach, adjust, tach. Not a good methodology, IMO. Furthermore, he crashed. Probably not related to the NV setting (this time).

I encouraged him to run a hose into the backplate cavity to be hooked onto the uniflow vent after filling. I know Brett sets his plane up so he has this option. I have my bEagle setup the same, but just use it all the time. If it's already there, I see no reason not to use it all the time. Anyway, ideally, we'd hold the tach steady, adjust the NV, get the rpm desired, and walk to the handle. Blocking the prop blast at the uniflow inlet doesn't help at all.  R%%%%  Steve

"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Mike Haverly

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Re: Lap times
« Reply #9 on: September 26, 2016, 11:39:44 PM »
I wondered where that piece of prop I found came from!
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Online Brett Buck

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Re: Lap times
« Reply #10 on: September 27, 2016, 12:22:25 AM »
Was launching for an unnamed flier this Sunday. Uniflow, tachometer, etc. Every time he reached for the NV, the engine leaned out, because his hand was blocking the prop blast into the uniflow vent. It went like this: Adjust, tach, adjust, tach, adjust, tach, adjust, tach. Not a good methodology, IMO. Furthermore, he crashed. Probably not related to the NV setting (this time).

I encouraged him to run a hose into the backplate cavity to be hooked onto the uniflow vent after filling. I know Brett sets his plane up so he has this option. I have my bEagle setup the same, but just use it all the time. If it's already there, I see no reason not to use it all the time. Anyway, ideally, we'd hold the tach steady, adjust the NV, get the rpm desired, and walk to the handle. Blocking the prop blast at the uniflow inlet doesn't help at all.  R%%%%  Steve

   And when it is hooked up for ram air, it does exactly the same thing. The trick, of course, is to tweak the needle, move your hand away so it has the ram air, then measure, repeat as necessary. For the PA, I routinely used the loop to suck air from the engine compartment and any sort of wind. For the Jett, the effect is very minimal and I usually just use ram air.

     But of course, merely dialing up a particular number without considering the other aspects is not the way to go. At local contests, particular if I don't have any recent practice, I will target 10,000 rpm as a safe starting RPM, within reason. If my last flight was in 100 degrees, and it's 60 degrees now (which is pretty common), I will open the needle regardless of what the tach says, or if my morning flight was OK, I will tweak the needle at least a few needle-widths regardless of what it says, that sort of thing. I last flew my #1 engine in 2007 when it was about 95 degrees, when I fired it up the next time  (in 2016), it was about 65 degrees, so I opened it up about two needle widths from the despite the fact that it seemed a little lean because it measured a little slow. Sure enough, once it cleaned itself up, it settled in very nicely. Of course, you have be able to remember stuff like that, but for good or bad,  I can usually recall what I had done before.


    Tachometers are very useful tools  but there's more than just the RPM reading.

     Brett

   

Offline Steve Helmick

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Re: Lap times
« Reply #11 on: September 27, 2016, 03:01:46 PM »
  "And when it is hooked up for ram air, it does exactly the same thing. The trick, of course, is to tweak the needle, move your hand away so it has the ram air, then measure, repeat as necessary. For the PA, I routinely used the loop to suck air from the engine compartment and any sort of wind."

Exactly. There's a problem, and there's a solution. I'm encouraging folks to see that it's a problem, and informing them of the solution. Muffler pressure is another potential solution. A lot of folks don't see problems and just try to live with them, I guess. I'd rather see the problem and find a solution. It's my Vulcan/German heritage, I reckon.  D>K Steve 
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Online Brett Buck

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Re: Lap times
« Reply #12 on: September 27, 2016, 03:27:59 PM »
  "And when it is hooked up for ram air, it does exactly the same thing. The trick, of course, is to tweak the needle, move your hand away so it has the ram air, then measure, repeat as necessary. For the PA, I routinely used the loop to suck air from the engine compartment and any sort of wind."

Exactly. There's a problem, and there's a solution. I'm encouraging folks to see that it's a problem, and informing them of the solution. Muffler pressure is another potential solution. A lot of folks don't see problems and just try to live with them, I guess. I'd rather see the problem and find a solution. It's my Vulcan/German heritage, I reckon.  D>K Steve 

    It is quite amazing how people just live with very simple problems, or create problems and never solve them, even when the solution is trivial.

    Brett

Offline Pat Chewning

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Re: Lap times
« Reply #13 on: September 27, 2016, 08:32:51 PM »
Lots of great comments about speed and performance of the airplane and of the pilot for various speeds and lap times.

But what about the judges?  Assuming that two flights are identical in shape of the maneuvers, do the judges give equal scores to a fast flight vs a slow flight?

I know that I like the looks of a pattern that is slow and majestic rather than quick.

Online Brett Buck

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Re: Lap times
« Reply #14 on: September 27, 2016, 09:31:59 PM »
Lots of great comments about speed and performance of the airplane and of the pilot for various speeds and lap times.

But what about the judges?  Assuming that two flights are identical in shape of the maneuvers, do the judges give equal scores to a fast flight vs a slow flight?

I know that I like the looks of a pattern that is slow and majestic rather than quick.

   If anything, you might get a higher score with a slightly faster speed, but I doubt that is because of the "impression", just that the airplane is usually more positive in the maneuvers instead of floating around.

     Judges want to see figures that look like the rule book, and anything else is at best speculation. Fly whatever speed it takes to make the flight more accurate, whether that's faster or slower.

    Brett

Offline Steve Helmick

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Re: Lap times
« Reply #15 on: September 28, 2016, 08:12:38 PM »
Yep, but I do keep urging Chris to bring out his .40VF Saturn. I loved to watch that thing fly, slow and precise. Not the blazing corners that Paul and Howard fly, and I miss the "slow-motion" pattern it showed. Bigger corner, thus downgraded. Don't get me wrong, I like the hard corner, but I still miss watching Chris flying his Saturn.  y1 Steve
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Tim Wescott

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Re: Lap times
« Reply #16 on: September 28, 2016, 08:50:22 PM »
Yep, but I do keep urging Chris to bring out his .40VF Saturn. I loved to watch that thing fly, slow and precise. Not the blazing corners that Paul and Howard fly, and I miss the "slow-motion" pattern it showed. Bigger corner, thus downgraded. Don't get me wrong, I like the hard corner, but I still miss watching Chris flying his Saturn.  y1 Steve

I wonder how much I downgrade big corners vs. other people -- I know that if you give me a tighter than usual corner followed with a wobble or a bow, I'm going to give you a lower score than if you give me a bigger than usual corner with a dead straight line following (if you give me a big round loop with itty-bitty flat spots -- I'll grade you down).
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