trim queston..

[Joe Yau]

I have this plane that seems to be light on line tension on part of the RWO maneuver..  It is fine on the upwind side on the initial vertical climb to near the top, then the line tension gets light or sometimes free air to about  45 degree point (down wind side) then it's fine, and same thing second time around.  I know its sort of strange.. usually the line tension goes light at 45 degree before the top..  I haven't tried anything yet, but I've added 2 grams of tip weight, and will have to wait till the weather clears again for the test flight.  meanwhile I'm just wondering if there is anything else I should try? or what cause this.

Thanks in advance

[Dave_Trible]

Joe these are sometimes guess work when you can't actually see or feel what's going on but I think it is one or more of the following.

1.  Maybe just to slow.  Or maybe need a bit more speed to overcome the other issues.
2.  Too much fuselage area behind the CG.  It's lifting the rear fuselage and weathervaining as you cross the top and wind gets under the rear fuse.
3.  Too nose heavy.  With not enough speed the nose is dropping past the top.
4.   Lead out position is too far forward.

Obviously the answer may be in reversing some of the above a little at  time and one it at a time until you find a better trim solution.  Do the easy stuff first.  Resist the urge to crank in a lot of rudder.  Just be sure it's not going the wrong way.  A little rudder ( maybe 5 degrees) to the outboard isn't too detrimental.  My real suspicion is its there in 2 and 3 above.  You might try getting the CG back a little and narrowing your handle line spacing to compensate.

[Joe Yau]

Joe these are sometimes guess work when you can't actually see or feel what's going on but I think it is one or more of the following.

1.  Maybe just to slow.  Or maybe need a bit more speed to overcome the other issues.
2.  Too much fuselage area behind the CG.  It's lifting the rear fuselage and weathervaining as you cross the top and wind gets under the rear fuse.
3.  Too nose heavy.  With not enough speed the nose is dropping past the top.
4.   Lead out position is too far forward.

Obviously the answer may be in reversing some of the above a little at  time and one it at a time until you find a better trim solution.  Do the easy stuff first.  Resist the urge to crank in a lot of rudder.  Just be sure it's not going the wrong way.  A little rudder ( maybe 5 degrees) to the outboard isn't too detrimental.  My real suspicion is its there in 2 and 3 above.  You might try getting the CG back a little and narrowing your handle line spacing to compensate.

Thanks Dave.

Some really good pointers.. It does feels like is #2 and maybe #3, or both.   and increasing the speed will usually cure most issues #1.  The design does have a fairly long/large surface area on the rudder (Primary Force), and because it is a flapless ship, the CG is more forward then my other planes.  and it is at the edge of nose heavy to o.k.. will have play with the CG as well, and maybe a little right rudder.   

[Randy Cuberly]

Thanks Dave.

Some really good pointers.. It does feels like is #2 and maybe #3, or both.   and increasing the speed will usually cure most issues #1.  The design does have a fairly long/large surface area on the rudder (Primary Force), and because it is a flapless ship, the CG is more forward then my other planes.  and it is at the edge of nose heavy to o.k.. will have play with the CG as well, and maybe a little right rudder.  

Joe,
You're on the right track by increasing the tip weight.  That almost always increases overhead tension.  The downside, of course, is that too much will cause other problems like dropping the outboard tip on squares etc.

I have to say nix to the rudder...that typically doesn't help much overhead...it might even make things worse.

Not knowing how the airplane is set up makes it difficult to make anything but generalizations about the trim problems.  Where are the leadouts in relation to the CG?   How long are your lines and what are your lap times.  What engine and prop are you using. 
Most often moving the leadouts FORWARD will increase line tension above 45 degrees...of course that is somewhat dependant on where they are now relative to the CG...Given what you've said I would NOT move them back first.
A little tail weight to put the CG where it belongs is also in order.

Randy Cuberly

[Joe Yau]

Joe,
You're on the right track by increasing the tip weight.  That almost always increases overhead tension.  The downside, of course, is that too much will cause other problems like dropping the outboard tip on squares etc.

I have to say nix to the rudder...that typically doesn't help much overhead...it might even make things worse.

Not knowing how the airplane is set up makes it difficult to make anything but generalizations about the trim problems.  Where are the leadouts in relation to the CG?   How long are your lines and what are your lap times.  What engine and prop are you using. 
Most often moving the leadouts FORWARD will increase line tension above 45 degrees...of course that is somewhat dependant on where they are now relative to the CG...Given what you've said I would NOT move them back first.
A little tail weight to put the CG where it belongs is also in order.

Randy Cuberly

Hi Randy,

The plane is pretty much in trim other then that one issue.. It has a Evolution .36 with a 3-blade Tornado 10x4. (launch at 9000rpm) Lines are .015 /61.5' i-i,  the CG is at 2 3/16" from LE. leadout are 1" behind the CG. I wasn't going to add offset to the rudder unless it's really necessary.. as it had a slight yaw issue before, and moving the LO forward helped. I guess will have to see if the tip weight works or not before trying something else.  Thx

[Ted Fancher]

Hi Randy,

The plane is pretty much in trim other then that one issue.. It has a Evolution .36 with a 3-blade Tornado 10x4. (launch at 9000rpm) Lines are .015 /61.5' i-i,  the CG is at 2 3/16" from LE. leadout are 1" behind the CG. I wasn't going to add offset to the rudder unless it's really necessary.. as it had a slight yaw issue before, and moving the LO forward helped. I guess will have to see if the tip weight works or not before trying something else.  Thx

Joe,

Give us some info on the airplane.  If it's a well known design some people might have some first hand experience.  Just knowing its size, weight, configuration (flapped/unflapped etc.) would be of benefit.  How far apart are the leadouts and where are you measuring their distance aft of the CG: to one or the other leadout?  to the midpoint between them? etc.

Off the first read however I'd question 9K revs on a four pitch prop.  Most any more or less four pitch I've worked with has required a minimum of 97-9800 or so to move the freight.  Unless the engine is picking up considerable RPM at launch 9K is unlikely to be a good setting for it.  I've no experience with the Evolution engine so can't predict what might be happening with it.

Ted

[Steve Helmick]

First, I'd suggest a different prop. From my experience, those Tornado 3 blade props don't work well. Try the TT Cyclone 11 x 4.5 and launch at about 9.5k to 9.7k.

Add more tip weight.  Add 1/4 oz and see if there's a change. If it's better, add another 1/4 oz. When it starts throwing the tip, start taking weight out. Some really good fliers (i.e., not me) will be able to tell the difference of 2-3 gram changes, but for most of us, 1/4 oz changes are at least noticeable. Eventually, we might want to revisit the tipweight and get more precise.

FWIW, I had the same problem with my "OPP" Eagle. Added three 1/4 oz weights in the tip box so far...at least it's safe, and my skilled (and highly paid) observer says it's not "throwing the tip" on hard corners.  Steve

[Bob Reeves]

First, I'd suggest a different prop. From my experience, those Tornado 3 blade props don't work well. Try the TT Cyclone 11 x 4.5 and launch at about 9.5k to 9.7k.

This is the first item I would try, you never did tell us what your lap times were. First indication of a wimpy powered airplane or one flying too slow is loosing line tension overhead.

[Joe Yau]

Joe,

Give us some info on the airplane.  If it's a well known design some people might have some first hand experience.  Just knowing its size, weight, configuration (flapped/unflapped etc.) would be of benefit.  How far apart are the leadouts and where are you measuring their distance aft of the CG: to one or the other leadout?  to the midpoint between them? etc.

Off the first read however I'd question 9K revs on a four pitch prop.  Most any more or less four pitch I've worked with has required a minimum of 97-9800 or so to move the freight.  Unless the engine is picking up considerable RPM at launch 9K is unlikely to be a good setting for it.  I've no experience with the Evolution engine so can't predict what might be happening with it.

Ted

 The plane is a Sig Primary Force / flapless profile.  (Pic below)  Weights 41oz,  LO are spaced 1  1/8" apart. and the 1" was measured at the mid point between them.

On the prop.. I had an APC 11x4 that worked quite well, but its heavy. (launch rpm was 9400), and I also have used a Xoar 11x4 wood prop.  launch at about 9400rpm as well.  The Tornado is a wide blade 3-blade, so the rpm is slightly lower for about the same lap time.  I like it around 9000rpm, but I do bring it up to 9150 or so in windy conditions. ( 5.25/ lap on 61.5'  i-i)   




 

First, I'd suggest a different prop. From my experience, those Tornado 3 blade props don't work well. Try the TT Cyclone 11 x 4.5 and launch at about 9.5k to 9.7k.

Add more tip weight.  Add 1/4 oz and see if there's a change. If it's better, add another 1/4 oz. When it starts throwing the tip, start taking weight out. Some really good fliers (i.e., not me) will be able to tell the difference of 2-3 gram changes, but for most of us, 1/4 oz changes are at least noticeable. Eventually, we might want to revisit the tipweight and get more precise.

FWIW, I had the same problem with my "OPP" Eagle. Added three 1/4 oz weights in the tip box so far...at least it's safe, and my skilled (and highly paid) observer says it's not "throwing the tip" on hard corners.  Steve

 The Tornado prop seems to work quite well in this set up..  the biggest difference I notice is the corners are much smoother comparing to the APC.  and seems to have good line tension everywhere other then part of the RWO maneuver..    I actually got less line tension from the Xoar.   

First indication of a wimpy powered airplane or one flying too slow is loosing line tension overhead.

I don't think this is the case..  as I have good line tension on the OH-8, just part of the RWO was an issue.  Lap time was around 5.25.

[Steve Helmick]

Did it do the same thing happen with the APC?  Steve

[Joe Yau]

Did it do the same thing happen with the APC?  Steve

It still goes light at times when the wind kicks up (same spot).   but the APC does have the best loc-on in level flight feel.. which I like. 

[Randy Cuberly]

Joe,
Since I understood you to say that this occurs when the wind "kicks up", can you tell me where relative to dead up wind you enter the wingover.  If it's dead upwind or slightly past up wind this line tension problem will nearly always occur.
Enter the wingover just slightly befor dead up wind...maybe 3-5 degrees before that point and the line tension will remain much more stable.  This is a truism that I learned from Bob Whitely many years ago...try it.
Obviously this applies to tension lost when the wind is blowing.  If the situation occurs in calm air then it is another trim problem such as those discussed before.

I do have to say that your statement that the airplane is well trimmed but loses line tension really doesn't make sense to me.  Well trimmed airplanes don't lose line tension except possibly under the circumstance I mentioned above.

Randy Cuberly

[Rick_Huff]

This may be a little off topic, but where do you measure (say for the LineIII program) the leadout position.  Front line, rear line or average of the two?   
Rick

[Randy Cuberly]

This may be a little off topic, but where do you measure (say for the LineIII program) the leadout position.  Front line, rear line or average of the two?   
Rick

Center between the two!

Randy Cuberly

[Joe Yau]

can you tell me where relative to dead up wind you enter the wingover.  If it's dead upwind or slightly past up wind this line tension problem will nearly always occur.

It is possible that it is dead upwind or slightly passed.

Enter the wingover just slightly befor dead up wind...maybe 3-5 degrees before that point and the line tension will remain much more stable.  This is a truism that I learned from Bob Whitely many years ago...try it.

much appreciate the tip..    I'll give that a try as well. 

Obviously this applies to tension lost when the wind is blowing.  If the situation occurs in calm air then it is another trim problem such as those discussed before.

There's no problem in calm air.  The plane is quite well behaved through out the whole pattern.    maybe just on the consecutive maneuvers, when the plane flys through it's own wake.. and I have to step back.

[Joe Yau]

Thanks for all the replies..    

Lots to think about.. CG, LO, prop, etc..  will check the tip weight first,  fly 5-7 degrees pass fly 3-5 degree before  the direct upwind for the RWO and see how that goes.  

[Brett Buck]

This is the first item I would try, you never did tell us what your lap times were. First indication of a wimpy powered airplane or one flying too slow is loosing line tension overhead.

  Something strange is going on with the engine for sure. Ted (as usual) is absolutely right, there is something odd if you have to launch at 9000 rpm to get a reasonable lap time. The Tornado 3-blades (the black GRP types, anyway) are excellent props and a pretty light load for this engine, so I would expect even a higher-than-normal launch RPM due to lack of unload. It sounds as if it unloads a huge amount, which doesn't sound right at all, like the engine is wimpy for some reason. Maybe the venturi is too small, perhaps? I think the Rustler-Merco 40 Metamorph launches at maybe 96-9700 with the same prop, and it's 4-stroking.

  Nonetheless, it also show some classic signs of yawing inboard.  At this point, even *I* would try adding a tiny bit of rudder offset and then adjusting the leadouts for minimum yaw reaction in squares, then see if it improves. I would also check that the fuselage is straight right before every flight. Profiles are absolutely notorious for not having stable alignment over environmental changes, in particular, they tend to bend like the metal thing in your wall thermostat if the Sun is on one side for any length of time. We have some unfortunate experiences with that, too.

   Brett

[Randy Cuberly]

It is possible that it is dead upwind or slightly passed.

much appreciate the tip..    I'll give that a try as well. 

There's no problem in calm air.  The plane is quite well behaved through out the whole pattern.    maybe just on the consecutive maneuvers, when the plane flys through it's own wake.. and I have to step back.

Joe....I said 3-5 degrees before dead upwind...not past!

Randy Cuberly

[Tim Wescott]

Something strange is going on with the engine for sure. Ted (as usual) is absolutely right, there is something odd if you have to launch at 9000 rpm to get a reasonable lap time.

I hope I'm not hijacking Joe's thread too much here -- but I launch an OS LA 46 with a 12.25x3.75 prop at 9050 RPM.  It audibly speeds up to a fast two-stroke for the first lap, then settles down to barely-not-four-stroke, two-stroke run for all but the last few laps where it speeds up again.

And I'm loving the flights, and doing well enough to get respectable 'middle of the pack' scores in Advanced with it.

[Joe Yau]

  Something strange is going on with the engine for sure. Ted (as usual) is absolutely right, there is something odd if you have to launch at 9000 rpm to get a reasonable lap time. The Tornado 3-blades (the black GRP types, anyway) are excellent props and a pretty light load for this engine, so I would expect even a higher-than-normal launch RPM due to lack of unload. It sounds as if it unloads a huge amount, which doesn't sound right at all, like the engine is wimpy for some reason. Maybe the venturi is too small, perhaps? I think the Rustler-Merco 40 Metamorph launches at maybe 96-9700 with the same prop, and it's 4-stroking.

Not sure if this makes any difference..  The Tornado prop is actually labeled as a "10x6". but it measures out to 4" at the tip,  and 5" at station 6 on the Prather guage, I put it on the plane and it performs close to a 4" pitch then a 6".

[Joe Yau]

Joe....I said 3-5 degrees before dead upwind...not past!

Randy Cuberly

Thanks for pointing that out.    not too awake on a Monday I guess..   

[Brett Buck]

Not sure if this makes any difference..  The Tornado prop is actually labeled as a "10x6". but it measures out to 4" at the tip,  and 5" at station 6 on the Prather guage, I put it on the plane and it performs close to a 4" pitch then a 6".

  Ah! That does make a difference, a huge one. I would say it is performing like a 10-6, by not having particularly good vertical performance.

   Brett

[Mark Scarborough]

I hope I'm not hijacking Joe's thread too much here -- but I launch an OS LA 46 with a 12.25x3.75 prop at 9050 RPM.  It audibly speeds up to a fast two-stroke for the first lap, then settles down to barely-not-four-stroke, two-stroke run for all but the last few laps where it speeds up again.

And I'm loving the flights, and doing well enough to get respectable 'middle of the pack' scores in Advanced with it.

its frikken amazing what a prop can do huh Tim
no seriously,, not poking at you,,

[Randy Cuberly]

I hope I'm not hijacking Joe's thread too much here -- but I launch an OS LA 46 with a 12.25x3.75 prop at 9050 RPM.  It audibly speeds up to a fast two-stroke for the first lap, then settles down to barely-not-four-stroke, two-stroke run for all but the last few laps where it speeds up again.

And I'm loving the flights, and doing well enough to get respectable 'middle of the pack' scores in Advanced with it.

9050 RPM with a 3.75 pitch prop....That seems really odd.  How long are your lines?

Typically on any of a half dozen airplanes I've flown or seen flown with prop pitches that shallow need something between 10,000  to 10,500 RPM to fly a reasonable speed.
I suspect that your engine must be really unloading in the air and picking up about 12 to 1500 RPM.
What size venturi are you running on the 46?

Curious,
Randy Cuberly

[john e. holliday]

He may have very dense air also.

[Joe Yau]

 Ah! That does make a difference, a huge one. I would say it is performing like a 10-6, by not having particularly good vertical performance.

   Brett

So the 4" pitch on the APC is huge difference vs 4" pitch on the Tornado prop (both measured at the tip)? I did notice the Tornado prop is slightly undercambered.. but no phillip entry.

[Joe Yau]

9050 RPM with a 3.75 pitch prop....That seems really odd. 

I have come across an APC 12.25" x 3.75" that actually measures out to 4" pitch, both station #6 and at the tip. and a few that is really a 3.75 pitch. not sure if that's the case..

[Brett Buck]

So the 4" pitch on the APC is huge difference vs 4" pitch on the Tornado prop (both measured at the tip)? I did notice the Tornado prop is slightly undercambered.. but no phillip entry.

    I was comparing the Tornado 10-4 that you said you had to the 10-6 you actually had. We have run both props and knew what they needed to do and that's why the numbers didn't look right to Ted and me. It's a lot more like it assuming it was a 10-6, that sound like it could be in the ballpark.

    The camber makes a huge difference in the effective pitch, and the semi-symmetrical airfoil affects the measurement, at least. At the tip, particularly, the angle gauge greatly underestimates the effect of the camber.  APC vs Tornado= apples and oranges.

   By the way, don't overlook the second part of my answer above. With the prop/engine speed issue resolved, look at the rest of the trim.

     Brett

[Tim Wescott]

9050 RPM with a 3.75 pitch prop....That seems really odd.  How long are your lines?

Typically on any of a half dozen airplanes I've flown or seen flown with prop pitches that shallow need something between 10,000  to 10,500 RPM to fly a reasonable speed.
I suspect that your engine must be really unloading in the air and picking up about 12 to 1500 RPM.
What size venturi are you running on the 46?

64 feet.

Yes, it's definitely unloading.

The venturi is, um, about that size -- it looks pretty much like others that I've seen, but with three layers of fine-mesh purple nylon net over it, 'cause that's what I needed to keep the engine from running away.  I haven't looked down it's little throat since I got the plane dialed in last spring.

[Joe Yau]

   I was comparing the Tornado 10-4 that you said you had to the 10-6 you actually had. We have run both props and knew what they needed to do and that's why the numbers didn't look right to Ted and me. It's a lot more like it assuming it was a 10-6, that sound like it could be in the ballpark.

I didn't know there was actually a 10-4 version.. I just went with what was measured.

Nonetheless, it also show some classic signs of yawing inboard.  At this point, even *I* would try adding a tiny bit of rudder offset and then adjusting the leadouts for minimum yaw reaction in squares, then see if it improves. I would also check that the fuselage is straight right before every flight. Profiles are absolutely notorious for not having stable alignment over environmental changes, in particular, they tend to bend like the metal thing in your wall thermostat if the Sun is on one side for any length of time. We have some unfortunate experiences with that, too.

It already has a bit of right rudder (1-2 degree), and the fuse is quite straight. The LO was adjusted with the set rudder position.  I guess I could try more rudder, but the plane flys fine as is. and has good line tension in all maneuvers other then part of the RWO in windy conditions.
 

 

[Mark Scarborough]

64 feet.

Yes, it's definitely unloading.

The venturi is, um, about that size -- it looks pretty much like others that I've seen, but with three layers of fine-mesh purple nylon net over it, 'cause that's what I needed to keep the engine from running away.  I haven't looked down it's little throat since I got the plane dialed in last spring.

Tim Tim ,, thats like soldering a transistor into a PCB and saying,, well it looks just like the other ones,, sigh,,

now that we have you using a tack I suppose the next thing is to get you to look at your ventruri size,, 

[Paul Walker]

Joe,
Chris is right near you. He should have a look to help you.

[Brett Buck]

I didn't know there was actually a 10-4 version.. I just went with what was measured.

 
It already has a bit of right rudder (1-2 degree), and the fuse is quite straight. The LO was adjusted with the set rudder position.  I guess I could try more rudder, but the plane flys fine as is. and has good line tension in all maneuvers other then part of the RWO in windy conditions.
 

 

      OK, Joe, I thought it didn't "fly just fine as is", hence you were asking for advice.  I don't know what to tell you at this point, this was just my best guess.

   In any case, flying of faster, or at least using less pitch at the same level flight speed, will likely improve this point in the pattern.

     Brett

[Paul Walker]

Don't hesitate to have Alan take a test flight either!

[Mike Haverly]

Don't hesitate to have Alan take a test flight either!

Perfect!  Just figure out how to put the lead outs in the other wing.

[Tim Wescott]

Tim Tim ,, thats like soldering a transistor into a PCB and saying,, well it looks just like the other ones,, sigh,,

Uh -- that's not how it's done?

Boy, this could go a long way to explaining some problems I've seen.

[Paul Walker]

Perfect!  Just figure out how to put the lead outs in the other wing.

OK Mike, so you want everything perfect, and it's not even your plane!

[Mike Haverly]

OK Mike, so you want everything perfect, and it's not even your plane!

   Probably a habit I've picked up from the company I keep.

[Joe Yau]

Joe,
Chris is right near you. He should have a look to help you.

Hi Paul,
I haven't seen Chris or Alan at the field since New Year day's Polar bear fun-fly..  It must be the cold temp or something.

Don't hesitate to have Alan take a test flight either!

Oh yes..  I'm sure he would test fly it. 

[Alan Resinger]

Actually, Paul let me fly his test bed piped ship back in the late 80's.  If I remember, correctly, it was the day you came up on a Sunday to fly with Arden.  It was the day he arrived from China.  Paul flew his quickly assembled 4 stroke, as his Skywriter was still in his travel box.
Paul trusted me with it although he looked a bit concerned when I went out and picked up the handle upside down.  I flew the whole pattern starting from inverted flight.
Alan

[Steve Helmick]

Actually, Paul let me fly his test bed piped ship back in the late 80's.  If I remember, correctly, it was the day you came up on a Sunday to fly with Arden.  It was the day he arrived from China.  Paul flew his quickly assembled 4 stroke, as his Skywriter was still in his travel box.
Paul trusted me with it although he looked a bit concerned when I went out and picked up the handle upside down.  I flew the whole pattern starting from inverted flight.
Alan

Ah, just like Mike, who picks up the handle upside down every flight...on purpose. Jim Johnson also, IIRC.

As for Joe's "Primary Force"/Evo .36...I'd bet (Joe's) $2 that the TT Cyclone 11 x 4.5 would make a better combo than either the Tornado or the APC.  And possibly more tipweight. In one of Ted's essays, he suggests adding more tipweight (among other trim changes) for a windy day.    Steve

[Ted Fancher]

Joe,
Since I understood you to say that this occurs when the wind "kicks up", can you tell me where relative to dead up wind you enter the wingover.  If it's dead upwind or slightly past up wind this line tension problem will nearly always occur.
Enter the wingover just slightly befor dead up wind...maybe 3-5 degrees before that point and the line tension will remain much more stable.  This is a truism that I learned from Bob Whitely many years ago...try it.
Obviously this applies to tension lost when the wind is blowing.  If the situation occurs in calm air then it is another trim problem such as those discussed before.

I do have to say that your statement that the airplane is well trimmed but loses line tension really doesn't make sense to me.  Well trimmed airplanes don't lose line tension except possibly under the circumstance I mentioned above.

Randy Cuberly



Good catch, Randy.  Joe's comments about the wind slipped by me because I didn't yet know enough about the airplane itself.  Bob's advice is right on.  Be interesting to see what Joe has to say about it (I'm reading this in order a few days late so will read on to see if you've scored!)

[Doug Moon]

I flew a primary force for a while.  I built mine from Mike's plans and one of the first laser kits he made, but it should be pretty much the same plane.

I flew mine on an FP 25, LA 25, and an OS26 4s car motor on a tiny aluminum pipe with a tiny prop at an insanely high RPM.  It worked but FP was the best option.  

I flew on APCs of the 10" variety and the flattest pitch I could find. IIRC I think I had a 3 pitch.  Making sure to run the engine in a mildly rich 2s on the ground with only a minor burp here and there in level flight throughout the pattern.  No 2-4 stuff here. I ran Omega RC 10% nitro fuel and the FP LOVED IT!!  My FP 40 ran its best on that stuff too.  No, it's not stunt fuel but then again we aren't talking about a stunt engine either. Can't remember the RPMs off hand but it was well over 10K at launch. I wanted the RPMS as high as possible with the smaller motor keeping the engine in its designed power range.  I don't know off hand the timing of the evo 36 but if they are near what their RC counter parts are then you would want the recommended fuel to get the most consistent run. Horizon says the operating range for the evo 36 is 9300 to 17000.  You are just barely touching the operating range at take off.  This may lead to what I describe below about speeding up.

Things to try...

Take a lap time right before the RWO.  Then take it again after the round 8, and again after the clover.  You are describing a situation where it is just too rich for the over head pass in the winds, especially if you miss the wind.  The motor is still kind of cool at this point and has had no load placed on it yet.  It's probably still breaking and sounding normal but it is still a tad rich.  The lap times throughout will tell you right away if this is your issue.  It may not feel that way on the handle as the flight progresses because the performance increases with speed/power and you are able to properly fly the plane. If you are getting a large speed up by the end of the tank, more than .03 tenths.  You will want to look at how you have the tank plumbed or shimmed and see if you can get it down to .01-.02 speed up by the end of the flight.

I would also recommend taking the lines down to 60' i-i.  This was the max length I could get before the model would start faulter.  In your case you will go down on lap time to around 5 seconds but that wont be bad at that length.  it would actually be pretty good especially if the lap times are consistant beginning to end. The increased speed will pull it through the RWO that much better.

I would recommend staying with the flattest APCs you can find, even if you have to go down in diameter, get the RPMs up, way up! With that restrictive muffler you can mimic a piped system with high RPMs and flat pitches.  Run it 2-2 and you can hear the soundwave rattle on the ground before launch. It' works really good once you get it the right range.

[Ted Fancher]

Thanks for all the replies..    

Lots to think about.. CG, LO, prop, etc..  will check the tip weight first, fly 5-7 degrees pass the direct upwind for the RWO and see how that goes.  

Joe!


No, no, no!!!  You need to start before directly upwind.  Your goal should be to have the airplane vertical at or just before directly upwind.  In the case you've described I'd suggest having the "up track" slightly prior to directly up wind as you will find the wind actually gives you a boost up and over. 

A number of  years ago I wrote several consecutive Model Aviation Stunt columns entitled Fly Like a Champion that covers a lot of material about dealing with winds and other of Mother Nature's attempts to destroy our patterns.  Send me a private message with your email address and I'll try to scan them and forward them to you.

ted

[Tim Wescott]

A number of  years ago I wrote several consecutive Model Aviation Stunt columns entitled Fly Like a Champion that covers a lot of material about dealing with winds and other of Mother Nature's attempts to destroy our patterns.  Send me a private message with your email address and I'll try to scan them and forward them to you.

Post the issue dates?  I'd like to read those, and if I don't have them in my archives I'll be able to snag them off the AMA site!

Thanks.

[Ted Fancher]

Not sure if this makes any difference..  The Tornado prop is actually labeled as a "10x6". but it measures out to 4" at the tip,  and 5" at station 6 on the Prather guage, I put it on the plane and it performs close to a 4" pitch then a 6".

Glad you clarified that, Joe.  Didn't make sense if it was the Tornado 10X4 three blade.  I used the 10X6 on some of my ships but mostly use the four pitch and have started doing so on my Ruffy since I went to higher nitro, all castor fuel with a bigger intake.  The little Merco grew some balls after those changes.  I launch in the vicinity of 10K and that's where the run described by Brett comes into play.  It's strong and speed consistent.  With the 10X6 it was just too fast to fly really well at an RPM that let the engine run with any gusto.

By the way, I've absolutely loved the way the Tornadoes have flown several of my classic ships, including the smushed Nobler, the Tucker Special and the Chizler all of which had good records at the VSC and Nats events, even winning a couple.  

Ted

Ted

[Ted Fancher]

Post the issue dates?  I'd like to read those, and if I don't have them in my archives I'll be able to snag them off the AMA site!

Thanks.

Tim,

I'm at work right now saving the world from aviation disaster.  When I get home I'll look it up in my um...er...sorta...library.  I know they're there somewhere because I sent copies to Don Chandler a month or two ago.  Send me a PM with your email, too, Tim.

Ted

[Trostle]

Joe!



A number of  years ago I wrote several consecutive Model Aviation Stunt columns entitled Fly Like a Champion that covers a lot of material about dealing with winds and other of Mother Nature's attempts to destroy our patterns.  Send me a private message with your email address and I'll try to scan them and forward them to you.

ted

I hope that Ted does not mind that I step in here and help him avoid his search through his vast archives of stunt lore and trivia.

Ted wrote the Stunt Column in Model Aviation from May 1984 through April 1990.  His three-part series on "Fly Like a Champion"  appeared in his column in the June, July and August 1986 issues of Model Aviation.

For those doing a search:

June 1986 started on page 63
July 1986 started on page 69
August 1986 started on page 69

About 10 pages in all.

Over the years, a common practice of the devoted people who wrote these stunt columns in the magazines was to devote several columns on flying the pattern.  Ted's was one of the best.

Keith

[Ted Fancher]

Thanks, Keith.  I appreciate the assist!  Can you actually search for MA ariticles at the AMA site?

Ted

[Joe Yau]

       In any case, flying of faster, or at least using less pitch at the same level flight speed, will likely improve this point in the pattern.

     Brett

I might repitch the prop to 3.75" but will see.