"Run Time" / Altitude Change.... any Rules of Thumb?

[Skip Chernoff]

I've found that as I fly at higher elevations my planes use less fuel than at sea level. Are there any charts or rules of thumb to help me predict my fuel load "starting point"? Here's a hypothetical example:

At sea level I need 5oz of fuel with my La46 powered stunter to get the pattern in.Suppose I'm going to a contest at 2000ft. elevation. Because of travel I won't be able to practice or "time a run" prior to competing....how do I know how much fuel to start with?    Thanks,PhillySkip

[Dan McEntee]

  No rule of thumb that I am aware off. Just a matter of putting up a flight with your standard fuel load, get an accurate time, and adjust from there. It depends on your model , it's weight, prop, air temperature and how the engine is loading. Warm and thin air has less oxygen so you need less fuel for the same mixture. Colder or more dense air requires more fuel. You might ask local flyers what they are running and what they use in a typical flight.. here in St. Louis, we are any where from 200 to 400 feet above sea level. When we use to go to SIG in June, we used much less fuel, sometimes up to 3/4 ounce less, and they are around 800 feet, I think. Just try to get a few practice flights.
   Type at you later,
    Dan McEntee

[Brett Buck]

I've found that as I fly at higher elevations my planes use less fuel than at sea level. Are there any charts or rules of thumb to help me predict my fuel load "starting point"? Here's a hypothetical example:

At sea level I need 5oz of fuel with my La46 powered stunter to get the pattern in.Suppose I'm going to a contest at 2000ft. elevation. Because of travel I won't be able to practice or "time a run" prior to competing....how do I know how much fuel to start with?    Thanks,PhillySkip

    Trick question, because you are going to add nitro until you get the same run time from the same amount of fuel, right?

    I would guess that, all else being equal, that if you run the same fuel, you will be in the range of about 3.75-4 ounces and it will have to run in meltdown mode to get the same lap times. I also guess that if you normally run 10%, you should try some 20% nitro fuel to get about the same time on about 5 ounces. That's based on comparing Tucson to home, 2200 feet to ~0 feet.

   You should definitely test it, if not, start with your normal fuel and 4.5 ounces and whip and/or do cutoff loops if it looks like it is going to go over - then test it between rounds.

    Brett

[Skip Chernoff]

Thanks guys. This "run time" thing makes me nuts. At Brodak's this year I ran out of fuel on two different planes and on a third plane went overtime by 1 1/2 minutes. This was after I timed runs on all three planes the day before and thought I had my settings correct or at least in the ball park.

[Dan McEntee]

Thanks guys. This "run time" thing makes me nuts. At Brodak's this year I ran out of fuel on two different planes and on a third plane went overtime by 1 1/2 minutes. This was after I timed runs on all three planes the day before and thought I had my settings correct or at least in the ball park.

  That has happened to all of us at one time or another. That's why it pays to stick with one airplane and not skip around to two or three different airplane/engine combos. I time every flight even if I'm just goofing around. That way you can see trends if something like the glow plug or even your fuel is changing. I forgot to mention the nitro trick like Brett talked about. I never did get to master that skill, and just go with what I brought. You won't see much difference in power at a few hundred feet difference but from your location to say, Denver or even Tucson as mentioned will have you paying real attention to how things are working. test flights are still your best friend.
   Type at you later,
   Dan McEntee

[Chris Fretz]

I've found that as I fly at higher elevations my planes use less fuel than at sea level. Are there any charts or rules of thumb to help me predict my fuel load "starting point"? Here's a hypothetical example:

At sea level I need 5oz of fuel with my La46 powered stunter to get the pattern in.Suppose I'm going to a contest at 2000ft. elevation. Because of travel I won't be able to practice or "time a run" prior to competing....how do I know how much fuel to start with?    Thanks,PhillySkip

What kind of tank are you running?

Chris

[Chris Fretz]

   You should definitely test it, if not, start with your normal fuel and 4.5 ounces and whip and/or do cutoff loops if it looks like it is going to go over - then test it between rounds.

    Brett

What do you mean by whip and cutoff loops?

Chris

[Al Ferraro]

Skip at Brodak I had to turn my needle in a little more than a 1/4 turn to get the same engine run that I had in NJ, LA .40, 4-1/2 oz tank, Powermaster GMA 10% 22oil fuel. The first fight was 7:43 run time which is cutting it to close, so on the second fight I filled the tank and pulled out 15cc and got a 6:34 run time on the same needle setting. I'm new too this to and was also scratching my head trying to figure it out what was going on.
Al

[Brett Buck]

What do you mean by whip and cutoff loops?

   Whipping the airplane is a standard CL technique that allows you to drag the airplane faster by "leading" it with your arm. Its the reason speed planes are timed with the pilot's arm in a pylon - so you can't whip it. It's very easy and you can fly small airplanes entirely by whipping. You can take a slab-wing 1/2A and maybe double the speed by whipping, and fly it for a long time (until you get tired) after the engine quits. It's very difficult on a good stunt plane, because the engine/prop/pipe want to fight any speed increase, usually by going rich - which will make it run out of fuel faster!  I did it this weekend when I was trying to keep from overrunning (long and stupid story...) and it may have cut 5 seconds out of the run.

   Cutoff loops are just that, loops at the end to cut off the engine. If you just fly around level, you will generally run the tank completely out of fuel. However, it has long been known that if you do a positive-G maneuver when it is low on fuel, it will run the fuel away from the pickup and cause the engine to quit. Typically, you do a loop at relatively high elevation (say, start at 30 degrees) on the downwind side, and that will cause the engine to quit with a little fuel left. Depending on your tank, you might be able to cut it off with maybe 1/4 ounce of fuel left, which might be 15-30 seconds sooner than if you let it run out in level flight.

    The point being, there's something you can do if you have a bit too much fuel, so err on the side of too much rather than too little. If you are uncertain, put in a little extra, make sure you get through the flight, and then whip it to richen it up and cut if off with some fuel left.

    Brett

[Brett Buck]

Thanks guys. This "run time" thing makes me nuts. At Brodak's this year I ran out of fuel on two different planes and on a third plane went overtime by 1 1/2 minutes. This was after I timed runs on all three planes the day before and thought I had my settings correct or at least in the ball park.

     Carmichaels is 1004 feet, which is almost the same as the NATs. In the very unlikely event I ever fly there, going from dry sea level air, I would set up just like the NATs (Muncie is 962 feet and similarly humid), that is, 15% nitro and no other changes. That's probably a little much, so if you really wanted to hi-fi it, with 5 ounces of fuel, suck 2 ounces out of the 15% can and the rest out of the 10% can for each flight, that will get it very close.

   Note that the point is to make the engine run like it normally does. Of course you could just figure out the reduced fuel load for your regular fuel (which will be around 4.25 ounces or a little more, I guess) but in that case it will run much leaner and with much less power than you are used to.

      If you have everything working, and you are living in the eastern US as your baseline, it will require less of a change than I would. But the basic idea still works. Note also that  flying around here, I can use the same settings and nearly the same fuel load at any temperature. I have to make sure and get the tank absolutely full in the mornings with temperatures in the 60's, and I might pull out 1/4 ounce or so (from a 6.7 ounce tank) in the afternoon when it's around 100. It clearly does lose power but not enough to make much difference. Note that that is density altitude change of around 3000 feet and no consequential changes are required. But go to Muncie at ~1000 feet and otherwise similar temperatures, and it takes a pretty big change, and 2200 feet at Tucson takes an even bigger change

     Brett

[Randy Cuberly]

I believe the real key is Nitro, as Brett said in the beginning!  When you go to a higher elevation or area with much higher heat (density altitude increase much the same as going to higher elevation), what you're really interested in is getting about the same power that you're used to using at home.  The easiest way to do that is simply add nitro to your fuel.  Most of the experts carry two different nitro levels of fuel with the same amount of oil in each, then just mix the higher content with the lower content fuel in the syringe.  For instance 2 oz of 10% nitro and 2 oz of 20% nitro in the syringe give you 15% nitro with still the same percentage of oil.  I'm sure you get the idea.  Stick to the half and half and it's easy to calculate.  I usually carry 15% and 30% with 20% oil for my PA's.  I typically fly at high altitude and high heat!

AS Bret alluded to earlier, when you get to a mix that gives you about the same type of run you have at home with a similar needle setting you will use about the same amount of fuel.  

Seriously, it's not as complicated as it may sound!

I would add one thing.  If you're going to compete always get to a contest early enough to get in a practice flight or two.  If you're really serious go at least a day early and fly, fly, fly!

Randy Cuberly

[Chris Fretz]

  Whipping the airplane is a standard CL technique that allows you to drag the airplane faster by "leading" it with your arm. Its the reason speed planes are timed with the pilot's arm in a pylon - so you can't whip it. It's very easy and you can fly small airplanes entirely by whipping. You can take a slab-wing 1/2A and maybe double the speed by whipping, and fly it for a long time (until you get tired) after the engine quits. It's very difficult on a good stunt plane, because the engine/prop/pipe want to fight any speed increase, usually by going rich - which will make it run out of fuel faster!  I did it this weekend when I was trying to keep from overrunning (long and stupid story...) and it may have cut 5 seconds out of the run.

   Cutoff loops are just that, loops at the end to cut off the engine. If you just fly around level, you will generally run the tank completely out of fuel. However, it has long been known that if you do a positive-G maneuver when it is low on fuel, it will run the fuel away from the pickup and cause the engine to quit. Typically, you do a loop at relatively high elevation (say, start at 30 degrees) on the downwind side, and that will cause the engine to quit with a little fuel left. Depending on your tank, you might be able to cut it off with maybe 1/4 ounce of fuel left, which might be 15-30 seconds sooner than if you let it run out in level flight.

    The point being, there's something you can do if you have a bit too much fuel, so err on the side of too much rather than too little. If you are uncertain, put in a little extra, make sure you get through the flight, and then whip it to richen it up and cut if off with some fuel left.

    Brett

So it won't cut off unless you whip it to richen it up?

Chris

[Brett Buck]

So it won't cut off unless you whip it to richen it up?

Chris

  Two separate techniques, you can use either or both.

    Brett

[Dennis Moritz]

I count laps when adjusting run time. I work up to the full pattern when adjusting to field conditions and altitude. I fly through the hour glass, if engine sounds right. Then count laps after. If all seems ok I'll fly the rest of the pattern and adjust fuel load from there. This assumes some practice flights are possible. If I'm getting a temperamental needle setting I add nitro by mixing higher nitro fuel with milder fuel. Go through lap count again when engine is happy. Brodak flights benefit from this process. Same with the NATs.


Sent from my iPhone using Tapatalk

[Chris Fretz]

  Two separate techniques, you can use either or both.

    Brett

Ok I'm confused then. Wouldnt everyone cut out on the clover being it's the last stunt and the tank should be pretty empty at that point?

Chris

[Dave_Trible]

Ok I'm confused then. Wouldnt everyone cut out on the clover being it's the last stunt and the tank should be pretty empty at that point?

Chris

Absolutely can if you aren't careful.  Tank design can be important here.  You'll still need to know your equipment  pretty well.  You'll need enough to safely get through the pattern and just enough for a handful more laps after- so you may still need to pull some out.  I can try to shut mine off over and over but until I hear the engine step up a little leaner and perhaps get the first light burp I'm wasting my time.  Hence,  I still have to measure out fuel to get that to happen at the right time after the clover.

Dave

I think it might be a waste of time to try to cypher it.  Just get there early and fly.  KC and Muncie are at about the same elevation and when I get to the Nats I don't usually need to touch the needle much or change prop pitch.  However I need to pull out nearly a full ounce more fuel.  It's been said that Muncie is like someone put a dome over it and pulled the oxygen out.

[Brett Buck]

Ok I'm confused then. Wouldnt everyone cut out on the clover being it's the last stunt and the tank should be pretty empty at that point?

   You have to have enough fuel left to get through the clover, and then run a few (3-4 laps), at which point the fuel is low enough to cut it off. If you run short on fuel, it *will* cut off in the first loop of the clover (like it did to me at the 1995 NATs on Top 20 day), and many of them go lean for a while then.

    Brett

[Dan McEntee]

Ok I'm confused then. Wouldnt everyone cut out on the clover being it's the last stunt and the tank should be pretty empty at that point?

Chris

       One thing to keep in mind in all of this, is that you have 8 minutes from signal to the judges ( and you flip the prop or hit the switch) to do the pattern and land until the wheels stop. If you are a "typical" Joe Bellcrank, most guys fly in the 5 to 5.4 seconds per lap range. If you don't take any extra laps, you should be finished with the pattern between 5:45 and 6 minutes. As you practice and even sport fly, time every flight from engine start to when the model stops to get a real good base line on what you need. Some guys count laps after the clover, and adjust fuel for a certain number of laps after the clover, 8 or 10 laps which is another 50 to 60 seconds. When you do the clover, if you have at least a half ounce or more of fuel in the tank, you should be OK in the clover unless you make the loops really tight. Making the maneuver the proper size here is important. If you find that you are running long at say, 7 minutes and 15 seconds, you can try a nice big loop followed by a nice tight loop and see what happens. If it continues to run normally, give it another few laps and try again. This is something that takes some practice also, so by timing each flight with a given amount of fuel, you can tell by your watch when you think it will quit on it's own, and try a cut off loop 30 seconds before that time to see what happens. Like the rest of the whole pattern, practice makes perfect! NOW!!! One thing to keep in mind also after this whole long discussion is that the cut off loop doesn't really work with a clunk tank. It basically only works with a metal tank with stationary fuel pick up. So iff you use a clunk tank, Bretts whip method is your only recourse, and keeping the model low while doing that will help also.
  There sure is a whole lot more to this competition stunt game than a lot of people realize, isn't there??? If you want to split the hair even further, in FAI events, you only have SEVEN minutes to do all of this!
    Type at you later,
   Dan McEntee

[Steve Helmick]

Worth noting that clunk tanks are not willing to agree to a "cutoff loop", but tin tanks are. Getting in your pattern within the 8 minutes with an engine is more challenging than with an electron burner, but in exchange, we get to savor the thrill of the grease, noise, vibration and glory.

I've never done this, but Brett may or may not have posted before about adding nitro as density altitude increases to get somewhere close to the same NV setting as at baseline. It makes sense. That should let you run about the same volume of fuel.

The other thing Brett may or may not have posted before is to always fill your tank and then remove the known quantity, or quantity that you'll have to determine on site.

Then again, if you are flying when the density altitude is much lower than normal, you'll be stressed to get enough run time, so then you make a quick run to buy some Coleman lantern/stove fuel and add a bit to the fuel you'll run that day...4 to 6 oz per gallon will get it done, so 1 to 1.5 oz per quart. We flew one contest at something like negative 1,100' density altitude...high baro pressure, low temp.   Steve

[Gary Dowler]

Ok, Ill bite.  What does the Coleman fuel do for you?

[Brett Buck]

Ok, Ill bite.  What does the Coleman fuel do for you?

    Adds energy density, and changes the required fuel/air ratio, with the net effect of slightly increasing the power per unit fuel consumption, or alternately, reducing the fuel consumption for a given amount of power. It's not very effective but if all you need is 15 seconds, it will work in most cases.

    Brett

[Chris Fretz]

The other thing Brett may or may not have posted before is to always fill your tank and then remove the known quantity, or quantity that you'll have to determine on site.

Why not just put less in the syringe instead of taking it back out?

Chris

[Dan McEntee]

Why not just put less in the syringe instead of taking it back out?

Chris

  If for some reason you don't burn all the fuel from the previous flight, that fuel is still in the tank and adds to what you put in next, making your next engine run longer. If your engine is running consistently and your engine shuts down out of fuel within a few seconds each flight after flight, then yes, you can just pull a syringe the correct amount. It pays to pay close attention to what amount makes your tank over flow also. Some tanks can vary a bit from their advertised capacity, and it's just good to know what the capacity is with the model sitting on it's wheels.
   Just as an aside to add, we all that are answering know this stuff because we have been there in your place and experienced the cause and effect. This was long before Al Gore invented the Internet!
   Type at you later,
    Dan McEntee

[Gary Dowler]

    Adds energy density, and changes the required fuel/air ratio, with the net effect of slightly increasing the power per unit fuel consumption, or alternately, reducing the fuel consumption for a given amount of power. It's not very effective but if all you need is 15 seconds, it will work in most cases.

    Brett

And now I know!  The amount you mentioned would have little effect on the oil percentage as well. 

[Brett Buck]

Why not just put less in the syringe instead of taking it back out?

     That was a different post the other day, but if you *do* cut it off with a cutoff loop, the whole point is to cut it off with some fuel remaining in the tank. If you do that, you are never quite sure how much was left over, so if you put in a fixed amount, you are never quite sure how much the total might be. Even if you fly around level and let it run "all the way out", that can mean different things in different conditions. It will be different if the engine is surging up and down from the wind, or running at a constant speed in the calm.

    Fill it up, then suck it out, you always know how much is in the tank.

     This might all seem excessive, but it's all part of mastering the craft. With AMA you have pretty good tolerance. I have flown maybe 100 flights at the Team Trials and haven't underrun or overrun even once, and I don't time my flights or do anything special aside from being careful.

     Brett

[john e. holliday]

I like how complicated this can get with all the different quantities of fuel being used per nitro and oil content.   I've witnessed guys putting up practice flights early in the AM in this part of the country and getting a needle setting.   Then when it came time to put up an official wonder why the run isn't the same because of temperature and humidity changes.  When I was playing with F2C we notice that Buder Park in St Louis was the worst.  Even in the later part of the day the humidity would be changing.  I still like the guys that say if a plane doesn't fly a certain lap speed it is not flying right.  To me it is a total of the pilot, the plane and engine run.  Of course as most will tell you the old DOC doesn't practice enough.  I do try to make my plane/engine combo as consistent as I can.

[Chris Fretz]

     That was a different post the other day, but if you *do* cut it off with a cutoff loop, the whole point is to cut it off with some fuel remaining in the tank. If you do that, you are never quite sure how much was left over, so if you put in a fixed amount, you are never quite sure how much the total might be. Even if you fly around level and let it run "all the way out", that can mean different things in different conditions. It will be different if the engine is surging up and down from the wind, or running at a constant speed in the calm.

    Fill it up, then suck it out, you always know how much is in the tank.

     This might all seem excessive, but it's all part of mastering the craft. With AMA you have pretty good tolerance. I have flown maybe 100 flights at the Team Trials and haven't underrun or overrun even once, and I don't time my flights or do anything special aside from being careful.

     Brett

I like how complicated this can get with all the different quantities of fuel being used per nitro and oil content.   I've witnessed guys putting up practice flights early in the AM in this part of the country and getting a needle setting.   Then when it came time to put up an official wonder why the run isn't the same because of temperature and humidity changes.  When I was playing with F2C we notice that Buder Park in St Louis was the worst.  Even in the later part of the day the humidity would be changing.  I still like the guys that say if a plane doesn't fly a certain lap speed it is not flying right.  To me it is a total of the pilot, the plane and engine run.  Of course as most will tell you the old DOC doesn't practice enough.  I do try to make my plane/engine combo as consistent as I can.

  If for some reason you don't burn all the fuel from the previous flight, that fuel is still in the tank and adds to what you put in next, making your next engine run longer. If your engine is running consistently and your engine shuts down out of fuel within a few seconds each flight after flight, then yes, you can just pull a syringe the correct amount. It pays to pay close attention to what amount makes your tank over flow also. Some tanks can vary a bit from their advertised capacity, and it's just good to know what the capacity is with the model sitting on it's wheels.
   Just as an aside to add, we all that are answering know this stuff because we have been there in your place and experienced the cause and effect. This was long before Al Gore invented the Internet!
   Type at you later,
    Dan McEntee

Boy fellas I do/have done everything wrong!

[Brett Buck]

I like how complicated this can get with all the different quantities of fuel being used per nitro and oil content.   I've witnessed guys putting up practice flights early in the AM in this part of the country and getting a needle setting.   Then when it came time to put up an official wonder why the run isn't the same because of temperature and humidity changes.  When I was playing with F2C we notice that Buder Park in St Louis was the worst.  Even in the later part of the day the humidity would be changing.  I still like the guys that say if a plane doesn't fly a certain lap speed it is not flying right. 

    What you have to do to be competitive at a high level is different from noodling around with sport flights.

    No one is compelled to do anything anyone says, but if people *do* want the benefit of others experience, why is it necessary to mock them?

    Brett

[tom brightbill]

     That was a different post the other day, but if you *do* cut it off with a cutoff loop, the whole point is to cut it off with some fuel remaining in the tank. If you do that, you are never quite sure how much was left over, so if you put in a fixed amount, you are never quite sure how much the total might be. Even if you fly around level and let it run "all the way out", that can mean different things in different conditions. It will be different if the engine is surging up and down from the wind, or running at a constant speed in the calm.

    Fill it up, then suck it out, you always know how much is in the tank.

     This might all seem excessive, but it's all part of mastering the craft. With AMA you have pretty good tolerance. I have flown maybe 100 flights at the Team Trials and haven't underrun or overrun even once, and I don't time my flights or do anything special aside from being careful.

     Brett

Sometimes it's been hard to accept, but I'm starting to understand. Brett and those who volunteer valid information based on experiences, not just opinions,  offer information that has brought me  forward. This is another example. Thank you.

[Chris Fretz]

     That was a different post the other day, but if you *do* cut it off with a cutoff loop, the whole point is to cut it off with some fuel remaining in the tank. If you do that, you are never quite sure how much was left over, so if you put in a fixed amount, you are never quite sure how much the total might be. Even if you fly around level and let it run "all the way out", that can mean different things in different conditions. It will be different if the engine is surging up and down from the wind, or running at a constant speed in the calm.

    Fill it up, then suck it out, you always know how much is in the tank.

     This might all seem excessive, but it's all part of mastering the craft. With AMA you have pretty good tolerance. I have flown maybe 100 flights at the Team Trials and haven't underrun or overrun even once, and I don't time my flights or do anything special aside from being careful.

     Brett

I have just this week been trying to learn the full pattern. I got through it Monday but ran way over 8 minutes.  Today I started using the fill it up suck it out method. First try ran 8min 10 sec.  Second try it started cutting out on the 2nd downward loop of the clover. So I abandoned the stunt and it ran 1 minute after that.  Is that normal or a tank problem?  Next I tried sucking out a little less but the flight was screwed from the beginning, stooge line popped off. By the time my helper launched it the test flight was no good. Flew the pattern anyway and it actually did cut off on the 2nd downward loop of the clover. Needless to say I landed upside down. Broke off my muffler pressure port. Tried another flight without pressure and it just went lean the whole time. So never did get a good timely run, then it got dark. Anyway besides the tank question, when does the 8 minute countdown start? When you raise your hand that you are ready to go or when the engine starts?

Chris

[Dan McEntee]

I have just this week been trying to learn the full pattern. I got through it Monday but ran way over 8 minutes.  Today I started using the fill it up suck it out method. First try ran 8min 10 sec.  Second try it started cutting out on the 2nd downward loop of the clover. So I abandoned the stunt and it ran 1 minute after that.  Is that normal or a tank problem?  Next I tried sucking out a little less but the flight was screwed from the beginning, stooge line popped off. By the time my helper launched it the test flight was no good. Flew the pattern anyway and it actually did cut off on the 2nd downward loop of the clover. Needless to say I landed upside down. Broke off my muffler pressure port. Tried another flight without pressure and it just went lean the whole time. So never did get a good timely run, then it got dark. Anyway besides the tank question, when does the 8 minute countdown start? When you raise your hand that you are ready to go or when the engine starts?

Chris

    The 8 minutes starts when you first flip the prop or flip the switch on your timer. You signal the judge as a courtesy, and I'm pretty sure by the rule book they start their watch when you flip the prop or flip the switch. If you are THAT new to the full pattern,put your emphasis on on getting confident in all of the maneuvers, but try to keep track or time and how much fuel you are using, and it won't hurt to put a little more in and push that 8 minutes just so you don't needlessly crash and airplane. As you get confident that you can do each trick right after the two laps between tricks, then start whittling away at being precise with your run times. getting to really know your engine and what it takes to start, and run time on allotted fuel is just part of it. Getting a good, one flip start at the beginning gets you on the way and buys a lot of time. Really practice that and do it the same way every time once you figure out what it takes as far as how much to choke it and such, and always have a really good battery for the glow plug. It's a lot of little things that once they all come together you will feel more confident at contests and even test flying.
  Good luck and have fun!
    Dan McEntee

[Brett Buck]

duplicate- still have a security certificate issue, this site show non-secure

[Brett Buck]

I have just this week been trying to learn the full pattern. I got through it Monday but ran way over 8 minutes.  Today I started using the fill it up suck it out method. First try ran 8min 10 sec.  Second try it started cutting out on the 2nd downward loop of the clover. So I abandoned the stunt and it ran 1 minute after that.  Is that normal or a tank problem? 

   It's a tank problem. The maneuvering is causing the fuel to slosh away from the pickup. When you do a loop near the end of the tank, the fuel wants to sling to the front of the tank, and towards the bottom of the tank. It wants to go to the front for two reasons - the drag of maneuvering slows the airplane rapidly, which makes the fuel want to run to the front. If it is an inside loop (like the first loop of the clover), the airplane will usually yaw the nose away from you, with tilts the entire airplane in such a way to make the fuel want to run to the front. Of course, the load of maneuvering makes the fuel want to move to the bottom of the tank.

   The net effect is that you can get air at the pickup, temporarily. This causes the engine to go lean a short time later - about where you said it did. This is how the cutoff loop works, if you had a little less fuel, it would have sucked air long enough to quit. In fact, if you had bailed out as you did, flew around level for 3-4 laps, then tried again, it would certainly have quit - thousands of stunt flights have ended that way on purpose.

     Of course if you fly around level, the fuel goes back to the normal spot along the wedge of the tanks and it runs most of the fuel out, so you get 8 minutes. You probably also get a lot of back-and-forth surging for several laps before it quits. Same thing, the airplane slows down, that sloshes the fuel to the front, that leans it out, it speeds up, sloshes the fuel to the back, picks up fuel again, goes rich, slows down, repeat.

     Some people think this is great, because it gives you lots of warning it's getting low on fuel. For competition, it's terrible, for the reasons you found - it screws you up in  the 4-leaf AND causes you to risk an overrun. What you really want is a tank that will run without changing anything about how it runs in the maneuvers, gives you no warning but will cut off very abruptly.  

  There are a few improvements you can make compared to standard hobby-shop tanks that will prevent this. The standard tank is either a copy of or a newly produced version of the Veco T21 tanks from the early 50's. Looking from the top/plan view, it is rectangular, and from the end, it's like a 3-story doghouse. Usually, it is shown with the inboard edge (bottom of the doghouse) flat up against the profile fuselage.

    The easiest thing to do is to put a shim under the rear of the tank, between the tank and the fuselage, to tilt the tank to the rear is kicked out. That make the fuel want to run to the rear of the tank under normal circumstances. 1/4" on a 4" tank is a good starting place. A variant of that is to make your own tank where the tank is tapered to begin with, the front being 3/8" or so narrower than the rear.

      The other problem is that the angle at the wedge (the roof of the "doghouse") is too flat. It needs to be about twice as sharp as a Veco T21. To fix this, you more-or-less have to make your own tank. It's actually quite easy. A very poor second alternative is to take a standard tank, remove both end caps (probably a good idea anyway so you can make sure the tubes are in the right spot and to clean it out), bend the wedge sharper, and then make new end caps to fit the weird new shape.

     Do those things, and it will cut off cleanly in most cases. One additional factor is the trim of the airplane. If it is yawed out a lot under normal circumstances, its like shimming the front end of the tank and will make the fuel tend to the front more than the back, and exacerbate the cutoff issues. That's why inside cutoff loops work, and outside cutoff loops don't work as well - the airplane yaws nose-in on outside loops, which runs the fuel to the rear of the tank.

 

Next I tried sucking out a little less but the flight was screwed from the beginning, stooge line popped off. By the time my helper launched it the test flight was no good. Flew the pattern anyway and it actually did cut off on the 2nd downward loop of the clover. Needless to say I landed upside down. Broke off my muffler pressure port. Tried another flight without pressure and it just went lean the whole time. So never did get a good timely run, then it got dark.

     Can't help you too much there, I think you learned something, anyway (if you have a problem, stop and fix it). If you tried without muffler pressure and without tweaking the needle out, then going lean is predictable. If you tweaked it out to run the same, then it ran away in the air, your venturi is probably too big.

Anyway besides the tank question, when does the 8 minute countdown start? When you raise your hand that you are ready to go or when the engine starts?

      I presume you mean AMA since you are talking about 8 minutes (vs 7 minutes in FAI), which matters because it's one of the few differences. In AMA, the time starts when you signal for start, and ends when the wheels stop rolling on the landing (or you crash). If you don't get it stopped on the ground before the 8 minutes, you lose the landing points (since you didn't complete the landing) and pattern points (because you did not attempt and complete all the maneuvers). I did it 3 days ago, cost me about 60 points and put me last in expert after the first round. I did better the second time around...

   In FAI, the timing starts *when the engine starts*. This is a very important, recent, change that was, near as I could tell, an accidental side effect of removing the 10 starting points. DO NOT hand signal,  just start cranking when you are ready.  When it starts, the timing should start. This saves you the time it takes to start the engine. Normally this is a few seconds, but if you have a problem, you get a huge amount of additional time over normal. This more-or-less solves the problem of having to take many attempts in FAI because now you don't have to worry about starting issues and running over at the end.

    Brett

[Brett Buck]

    The 8 minutes starts when you first flip the prop or flip the switch on your timer. You signal the judge as a courtesy, and I'm pretty sure by the rule book they start their watch when you flip the prop or flip the switch.

   I don't think so, it's at the hand signal.:

8. Duration of Flights.
Eight ( minutes total elapsed time is allowed from the time the contestant gives a hand signal prior to starting his engine (this should be done with a prearranged plan, and upon signal to or from judges) to start, take off, complete the flight pattern and land. Timing ends at either 8 minutes, when the model stops moving after successful landing, or when the model crashes. No maneuver, including the landing, will be scored after the eight ( minutes allowed have elapsed.

    In fact, if you don't give a hand signal and fly the flight anyway, you will get charged with an attempt (because you never signalled the beginning of your attempt, so it isn't an official flight, but you used up the 5 minutes):

7. Flight Procedure.
Each contestant will be called to the circle when it is his or her turn to fly. From the time they are called to the circle, contestants will have a maximum of five (5) minutes to give the hand signal to begin starting their engine(s). Once the starting hand signal has been given, contestants will be allowed a maximum of three (3) minutes to become airborne. A contestant may make as many starts as necessary, or may take off, land and restart if necessary, as long as the three minute time period has not been exceeded. If a second takeoff is made during the three minute time period, the first takeoff score will be canceled and a new score given. Failure to give the starting hand signal within five minutes of being called to the circle, or failure to become airborne within three minutes of giving the starting signal, shall be charged as an attempt. Contestants shall be allowed three (3) attempts to make two (2) official flights.

     Brett

[Tim Wescott]

    The 8 minutes starts when you first flip the prop or flip the switch on your timer. You signal the judge as a courtesy, and I'm pretty sure by the rule book they start their watch when you flip the prop or flip the switch.

In a world with Internet, there is absolutely no excuse for being "pretty sure" about the rules.  It's right there, in the book, and your PDF reader will let you search on key words like "hand" or "signal".  At any rate, it's 8 minutes from the hand signal, with various other fillets and decorations around how long you have to get airborne after the hand signal and how long you have to give the hand signal after you've been called to the circle, etc.

   I don't think so, it's at the hand signal.:

Unless the contest officials are feeling particularly generous.  I just checked the rulz.

    In fact, if you don't give a hand signal and fly the flight anyway, you will get charged with an attempt (because you never signalled the beginning of your attempt, so it isn't an official flight, but you used up the 5 minutes):

Or you might be chatting with a fellow competitor right after your flight and hear some former world champion loudly announce "I'm giving the hand signal now, TIM".

[Dan McEntee]

  I got the " time starts at the flip of the prop" in my mind because we were discussing that at a local contest one time and some one looked it up, and it was there. Maybe a recent change or he had an old rule book? At the same contest I think we had to deal with the "parts shed in flight" rule. I had a wheel pant come off in flight and was told I got a zero for the flight. I argued against that as it was a "foul" and should be charged an attempt. I had the rule fresh in my mind because I has a muffler bolt fail in flight on me at VSC the year before and was told the same thing. As I was fixing the muffler, Kieth Trostle told me that I should have a reflight coming and to argue for it. I forget who the judges were but they were 'known" in the stunt world and good judges, just not aware of the rule as it really doesn't come up very often. I was given the reflight and all was well. At this same local contest all sorts of stuff came up and I think wore the rule book out! Just one of those days but lots of lessons were learned all around. I just seem to remember that I was surprised at the "flip the prop" language and always figured it was the hand signal. In all the years I've done this I have never seen anyone that had an over run by a few seconds ever ask the judges when they started their watch!
   Another rule a lot of flyers are not aware of, (and some judges) is the flight doesn't become official until you pull out inverted in the reverse wing over. I have been the benefactor of that rule twice in my contest history. I went into the reverse wing over and got really blown out of it at the top. I saved the model by pulling out up right, did another lap to settle it down and then went into it again.  Bothe times the judges gave ne a zero for the maneuver and no patter points. I argued against it as it wasn't official until I pulled out inverted. A consultation with the CD both times got me a reflight. It is another one of those things that you really don't see very often  and so you're not used to what the routine should be. I haven't done a lot of contest flying in recent years and with the recent changes in line sizes and such I could use a good long sit down with the current rule book just to keep updated. I go back far enough in the event where we still had the 1 minute starting 5 point bonus rule in efect, and I sure did ALWAYS want that extra 5 points!
   Type at you later,
    Dan McEntee

[Brett Buck]

  I got the " time starts at the flip of the prop" in my mind because we were discussing that at a local contest one time and some one looked it up, and it was there. Maybe a recent change or he had an old rule book? 

   It's been that way for as long as I have been doing it, at least 35 years.

At the same contest I think we had to deal with the "parts shed in flight" rule. I had a wheel pant come off in flight and was told I got a zero for the flight. I argued against that as it was a "foul" and should be charged an attempt. I had the rule fresh in my mind because I has a muffler bolt fail in flight on me at VSC the year before and was told the same thing. As I was fixing the muffler, Kieth Trostle told me that I should have a reflight coming and to argue for it.

    It used to be that way, we called it the Howard Rush Rule. That one has changed recently (last 10 years or so), by a proposal from Howard himself. Dropping parts in flight now gets you an official flight with a score of zero  (which is how we had all incorrectly been reading it forever - now it really does read that way).

   

Another rule a lot of flyers are not aware of, (and some judges) is the flight doesn't become official until you pull out inverted in the reverse wing over. I have been the benefactor of that rule twice in my contest history. I went into the reverse wing over and got really blown out of it at the top. I saved the model by pulling out up right, did another lap to settle it down and then went into it again.  Bothe times the judges gave ne a zero for the maneuver and no patter points. I argued against it as it wasn't official until I pulled out inverted. A consultation with the CD both times got me a reflight. It is another one of those things that you really don't see very often  and so you're not used to what the routine should be.

     That's definitely right. What you did amounts to a warm-up maneuver, which was explicitly mentioned for years, somehow fell out of the rule book, and I put back a few cycles ago. I think it was *always* legal, even back to when we used a in-flight hand signal instead of the inverted pullout. The inverted pullout rule was put in to accomodate the problem of people ENDLESSLY forgetting the hand signal for official flight, and then doing 8-minute attempts on the circle. I still hand-signal sometimes out of force of old habit, but the in-flight hand signal now means nothing.

    Brett

[Chris Fretz]

 
 
     Can't help you too much there, I think you learned something, anyway (if you have a problem, stop and fix it). If you tried without muffler pressure and without tweaking the needle out, then going lean is predictable. If you tweaked it out to run the same, then it ran away in the air, your venturi is probably too big.

    Brett

The stooge line failed one other time this yr practicing the beginners pattern,  I think I just skipped the over head eights .So sadly  I didn't really learn anything from both times now that you mention it. But I do plan to fail proof the line now. Hopefully next time I'll stop and fix the problem, sometimes you can't fix stupid...

 

      I presume you mean AMA since you are talking about 8 minutes (vs 7 minutes in FAI), which matters because it's one of the few differences. In AMA, the time starts when you signal for start, and ends when the wheels stop rolling on the landing (or you crash). If you don't get it stopped on the ground before the 8 minutes, you lose the landing points (since you didn't complete the landing) and pattern points (because you did not attempt and complete all the maneuvers). I did it 3 days ago, cost me about 60 points and put me last in expert after the first round. I did better the second time around...

   In FAI, the timing starts *when the engine starts*. This is a very important, recent, change that was, near as I could tell, an accidental side effect of removing the 10 starting points. DO NOT hand signal,  just start cranking when you are ready.  When it starts, the timing should start. This saves you the time it takes to start the engine. Normally this is a few seconds, but if you have a problem, you get a huge amount of additional time over normal. This more-or-less solves the problem of having to take many attempts in FAI because now you don't have to worry about starting issues and running over at the end.

    Brett

What is FAI?

PAMPA contests are strictly AMA right?

Chris

[Chris Fretz]

  Whipping the airplane is a standard CL technique that allows you to drag the airplane faster by "leading" it with your arm. Its the reason speed planes are timed with the pilot's arm in a pylon - so you can't whip it. It's very easy and you can fly small airplanes entirely by whipping. You can take a slab-wing 1/2A and maybe double the speed by whipping, and fly it for a long time (until you get tired) after the engine quits. It's very difficult on a good stunt plane, because the engine/prop/pipe want to fight any speed increase, usually by going rich - which will make it run out of fuel faster!  I did it this weekend when I was trying to keep from overrunning (long and stupid story...) and it may have cut 5 seconds out of the run.

    Brett

If little Johnny spent hours building his beautiful stunt ship and it cut out inverted. Could you whip it and successfully get the airplane upright? Or are your chances better just just land it upside down?

Chris

[Brett Buck]

If little Johnny spent hours building his beautiful stunt ship and it cut out inverted. Could you whip it and successfully get the airplane upright? Or are your chances better just just land it upside down?

  Usually you are *much* better just taking your medicine and landing it inverted. I can recall only a few cases where someone managed to get it upright successfully, and only in a heavy wind where you could "wind-fly" it (another technique that you can learn) AND it wasn't already in level flight. I have *never* seen anyone managed to get it upright from inverted level flight. Usually even if you realize what to do and start immediately, it will go 1/3 way around the loop, run out of speed, yaw over into the middle of the circle, and crash near the pilot. I have seen it attempted *many* times and the result is highly predictable. Smaller airplanes, 1/2A's, etc, you can whip indefinitely, however, they won't make it around the loop.

    Stunt planes are particularly difficult to whip, because everything about them - the intentionally high parasitic drag, speed-regulating engine setups, and pretty large on pretty long lines  - is intended to keep external forces from causing a speed variation.

    Land it inverted and patch up the damage afterwards. We have also found that $53 Australian 3-blade propellors make excellent landing skids and usually keep at least the nose and canopy off the ground. You still have to fix the fin/rudder.

    Brett

[Brett Buck]

The stooge line failed one other time this yr practicing the beginners pattern,  I think I just skipped the over head eights .So sadly  I didn't really learn anything from both times now that you mention it. But I do plan to fail proof the line now. Hopefully next time I'll stop and fix the problem, sometimes you can't fix stupid...

It's a process

 

What is FAI?

PAMPA contests are strictly AMA right?

      In this context, this means FAI stunt rules, which are used for World Championships and the Team Trials, and essentially nowhere else in the USA.  They are used for foreign contests. The primary difference that matters here is how the flights are timed, and the fact that you get 7 minutes from engine start, instead of 8 minutes from the hand signal.   The scoring is different but (so far...) the maneuvers are all the same and the conduct of the flight is the same with one very minor exception.

    "PAMPA" contests use the conventional AMA rules (AMA official events 323-326), usually straight out of the rule book, with the rare and unfortunate exception that some East Coast contests omit appearance points.
 
     I included the comment because other people read this thread, too, and many people in the US have massive confusion about what the differences between FAI and conventional rules are - and it amounts, from the pilot's perspective, to the difference in the flight timing. It's much more critical to get the stuff we are talking about here correct in FAI.  Otherwise, and to your good fortune, no one in the USA really needs to know about the FAI or the FAI stunt rules, until you want to try to make the WC Team.

The FAI is the Federation Aeronautique Internationale, the self-appointed arbiters of all things in "world" aviation full-scale to model. Not surprisingly, it was started/was an outgrowth of early French aviation enthusiasts clubs.

   "World Records" are issued by them for anything that has the word "airplane" in it. Neil Armstrong had to go get himself an FAI sporting license in order to be recognized as the first man on the moon by foreigners, for example, and they recognized Yuri Gagarin as the first man in space*.   They don't consider some of the X-15 space flights to have been "real" space flights because they exceeded the recognized (but arbitrary) altitude threshold of 50 statute miles, but not the "FAI" requirement of 62 statute miles (the equally arbitrary 100 Km)

     The FAI is a collection of "international aero clubs". For the USA, this is the NAA, the National Aeronautic Association, which covers all forms of aviation from full scale to models. The AMA is a subset of the NAA, for example, as is the IAC (International Aerobatics Club) and some others.

      As it turns out the NAA is *by far* the largest National Aero Club in the FAI, and the AMA is *by far* the largest subset of the NAA, by orders of magnitude. So, the AMA is FAR AND AWAY the largest distinct section of the FAI.

      To further confuse the situation, PAMPA is a "special interest group" of the AMA. So as a hierarchy:

    FAI
           NAA
                AMA
                    PAMPA
                    IMAC
                    LSF
                    IRCHA
                    ...
                IAC  ( International Aerobatics Club)
                BFA (Balloon Flyers of America)
                ...
           French Aero Club
                ...
           Canadian Aero Club
                MAAC
                ....
        etc

   Brett


*the issue of FAI "spaceflight" records is particularly ridiculous and illustrative. The USA provides astronaut wings to anyone who goes above the almost entirely arbitrary altitude of 50 miles. The FAI chose the equally arbitrary 100 KM (62 miles), and later came up with the "Karman line" that is calculated from standard atmosphere parameters t justify it - which just happens to, through random luck that the universe apparently approves of, 100 Km, to justify it. The difference is negligible from the standpoint of aviation, there's no consequential air at either altitude .

    Also, well before the fact, the FAI had decided that to be a "true" spaceflight, the astronaut had to launch from the ground and stay with the spacecraft all the way back to the ground. Why they felt it necessary to define it that way, who knows, it's not like any of the other FAI member nations were doing anything at all to achieve it. Anyway, the USSR, being a proper "international" (read European) power, of course got all their cosmonauts including Yuri Gagarin and Gherman Titov FAI sporting licenses so they were "official" participants by FAI standards. As far as anyone can tell, no one in the USA bothered with that, "cowboys" that we are, although it's possible that some of the Mercury 7 were FAI members by extension of NAA or AMA membership.

    So, off goes Gagarin, first man in space. Of course, the FAI observers were nowhere to be found (and weren't invited) to his flight. Turns out, Gagarin (and later Titov) both ejected from their Vostok capsules because if they stayed with the capsule, they would probably be killed or heavily injured in the *far too hard* landing on the ground. It wasn't possible to meet the FAI rule of staying with your craft, so the ever-lovable USSR lied to the FAI about it and said they did, who was going to say different? So, technically, they hadn't met the FAI standard and didn't make an "official" space flight.

   Next up,  month later, Alan Shepard. He exceeded both the standard 50 miles and the FAI 62 miles, landing with the capsule. So, the "real" first man in space, an FAI hero, right? Oops, he doesn't have an FAI sporting license? Disqualified.

   Later, Joe Walker gets to 57 miles in the X-15. Less than 100 KM, non, disqualified.

      Of course, the real answer (which is the one the world currently goes with) is that ALL of these were "official" flights, the FAI rules be damned, they ALL went to space, Yuri Gagarin was first, it "counts", and the world moved on without the FAI sanction. You still get pissy little arguments about the X-15 flights above the threhold but below 100 Km, but for the most part the right thing was done -  without FAI input....

[Fredvon4]

This is why I try to read everything on theses sites

Especially Cox engine forum and here...

On the Cox engine forum I learn a LOT about other countries
and here I learn a lot of new things almost every day

Thanks Brett for the comprehensive answer!

[Brett Buck]

This is why I try to read everything on theses sites

Especially Cox engine forum and here...

On the Cox engine forum I learn a LOT about other countries
and here I learn a lot of new things almost every day

Thanks Brett for the comprehensive answer!

  You are welcome. Despite the dismal reputation the FAI in general has in the aerospace industry ("who the heck put you guys in charge?"), the *modeling* people are of the highest caliber, and are more-or-less the same as modelers in the USA. Peter Germann has, for something like 20 years, been running a FAI rules forum which has done very good work for everyone, sometimes to be thwarted at the annual meeting, but you have to try or nothing happens. He just posted the FAI rule  change ""plan" and schedule (I would hesitate to call it a process since there are several black boxes that tend to confound the best-laid plans) in the Rules forum.

     Brett

[Dan McEntee]

   I didn't know that the Russians had to eject out of their first capsules!!!!! I have never really read much about the early Russian endeavors anyway, but that is quite a surprise! At what altitude did this little maneuver take place? Anywhere near what Joe Kittinger  did on his record jump? That had to be as hairy as that first ride back into the atmosphere hopeing that the heat shield held and the 'chute opened!!??
   Type at you later,
   Dan McEntee

[Brett Buck]

   I didn't know that the Russians had to eject out of their first capsules!!!!!  I have never really read much about the early Russian endeavors anyway, but that is quite a surprise! At what altitude did this little maneuver take place? Anywhere near what Joe Kittinger  did on his record jump? That had to be as hairy as that first ride back into the atmosphere hopeing that the heat shield held and the 'chute opened!!??

   Not at high altitude, just before it hits the ground, presumably a few thousand feet. The capsule (spherical) had a heat shield and parachute, but the parachute wasn't *nearly* big enough to permit a safe ride all the way to the ground. So, they reentered, let it stabilize on the descent, down to pretty low altitude, then they ejected. All the Vostoks were that way. That's why they recruited Valentina Tereshkova - she was a civilian skydiver.

     The first Russians that landed in the capsule was the first Voskhod. There were three of them packed like sardines inside a Vostok with the ejection seat/capsule removed, and were seated at 90 degrees to the normal capsule axis, so all the instruments were tilted 90 degrees from the normal orientation from their perspective. It was so tight they couldn't wear spacesuits, either. It was just as much of a stunt as it sounds like, maybe the only space activity that you would normally classify as a stunt. On later Voskhods they reverted to two cosmonauts with spacesuits, but after the one spacewalk where Alexi Leonov had to mostly-deflate his spacesuit to get back in (because it ballooned and restricted his movement), they more or less scared themselves out of flying more missions. It was a complete death trap, if the booster failed, they all got blown up, because there was no escape system of any type.

  Of course, they waited for Soyuz and had a big lag in flights, which clearly lost them the "space race" since we were launching a mission every two months. And they rushed Soyuz, and after a series of serious failures in flight, they managed to accomplish a safe re-entry, but the parachutes failed, killing Vladimir Komarov.

    The reason that the Voskhod could land on solid ground was that they attached a rocket pack to the parachute shroud lines that applied a retro-fire when it was about 20-30 feet off the ground to soften the landing. They still do that on Soyuz, same arrangement and only slightly larger. You can see it work in the landing videos. Soyuz has a launch escape system as well, and it has been used and saved the cosmonauts.

   Mercury could safely land on the ocean and marginally safely on the ground because it had an airbag system. After re-entry, the heat shield was blown loose from the hard mounts and it fell down about 6 feet with a skirt, which formed an airbag to soften the hit. (see below). That's why there was a big flap during John Glenn's flight - the limit switches that indicated whether or not the heat shield had detached came on in orbit which, if true, means the heat shield was already loose. They left the retropack on to try to hold it if it was. Turns out, like most problems, the issue was only with the switch giving false telemetry.

   Gemini solved the landing shock problem by suspending the capsule horizontally so the load was "up/down" for the astronauts (and had a plan for a Rogallo wing/gliding parachute for horizontal landing, although that was abandoned as was a similar scheme for Apollo). Apollo seats had a shock absorber system inside but it was going to be *very* rough with a land landing.

    Brett

[Larry Fernandez]

Are there pattern points in FAI?

Larry, Buttafucco Stunt Team

[Brett Buck]

Are there pattern points in FAI?

   No. If you skip a maneuver, then it gets a zero. It is ambigious what happens otherwise (say, if you exit the maneuver improperly, there may be no penalty at all).

   Brett

[Trostle]

   No. If you skip a maneuver, then it gets a zero. It is ambigious what happens otherwise (say, if you exit the maneuver improperly, there may be no penalty at all).

   Brett

The FAI rules do define when a maneuver can receive a 0:

"Maneuvers omitted or not attempted at all.
"Maneuvers started but not completed.
"Maneuvers with an incorrect number of repeat figures (either too few or to many).
"Maneuvers flown out of sequence.
"Maneuvers flown without a minimum of 1 1/2 laps interval after the previous maneuver.
"Maneuvers performed after the maximum flight time of 7 minutes has elapsed.

The FAI rules also have the interesting bit to go along with the "out of sequence" item above:

"When a maneuver is omitted or not attempted at all, the remaining maneuvers shall be scored provided they are attempted in the correct order."

Then, there are paragraphs on how to score other than normal landings (like crashes, flip-overs, etc.)

An "improper exit", whatever that is for any particular maneuver is not really defined in the FAI rules.  Each maneuver is defined when it starts and when it ends.  Anything the model does during that maneuver that is not in accordance with the rules will be an error.

Keith

[Skip Chernoff]

Getting back to the original question of Run time /Altitude.....Yesterday at Hazelton Pa. with temps in the 90's and 1700' of altitude I ran 15% nitro in my HP40 powered Nobler I had great success. With gusting winds I ran the engine a bit leaner that I normally do. On 4 oz of fuel my run times were 6:30

I did win Intermediate PA but by the skin of my teeth. Chris Fretz( "Liner") flying Intermediate for the first time pushed me all day. We tied for high score on the 2nd round,but I had a better 1st round and got 1st. Chris is a fine flyer, a tough competitor,and a very nice guy. Congrats to Chris,....and to Bernie and Alan for putting on a great meet!

[Brett Buck]

Getting back to the original question of Run time /Altitude.....Yesterday at Hazelton Pa. with temps in the 90's and 1700' of altitude I ran 15% nitro in my HP40 powered Nobler I had great success. With gusting winds I ran the engine a bit leaner that I normally do. On 4 oz of fuel my run times were 6:30

   Congratulations!   Didn't have the guts to go all the way to 20%?   Could have gotten back to a normal fuel load/operating temperature.   But you can see the approach works.

        Brett