Plane Feels Floating During Outside Loop of Horizontal-8

[Kafin Noe’man]

I’ve been flying my Brodak P40 ARF for quite sometime and I really like it so far.

Since the engine setup and basic trim have been solved, I start to make some flying progress. This time is the horizontal 8.

However, everytime I do the horizontal 8, I often feel a bit loss of tension or floating when doing the outside loop part. The plane is not going inside or whatsoever (it’s a relief for me), but it just feels like floating and not ‘pulling’ out when it goes down and up to the top. The tension comes back pulling out when I’m at the exit of the horizontal 8 maneuver.

The wing—stab are parallel and level. No warp on both flaps and elevator as far as I can see.
I still have to make sure about that by flying some inverted flying and regular outside loops though.

So, I’m attaching you the link to my latest flying video, and I must admit that my horizontal 8 is still far from perfect. 
https://youtu.be/yrn9C6bW9DY?si=v6xdRPtl0pAWwdUb




A review from a fellow flyer tells me that
my outside loop part is tight and I’m over-rotating the intersection and past vertical before giving down when transitioning from the inside to outside.

Could that be the culprit?
If so, what’s the best way to learn in making outside loop bigger? Doing more lazy 8?

Looking forward to hearing more from you guys.


Best,
Kafin

[Brett Buck]

I’ve been flying my Brodak P40 ARF for quite sometime and I really like it so far.

Since the engine setup and basic trim have been solved, I start to make some flying progress. This time is the horizontal 8.

However, everytime I do the horizontal 8, I often feel a bit loss of tension or floating when doing the outside loop part. The plane is not going inside or whatsoever (it’s a relief for me), but it just feels like floating and not ‘pulling’ out when it goes down and up to the top. The tension comes back pulling out when I’m at the exit of the horizontal 8 maneuver.

The wing—stab are parallel and level. No warp on both flaps and elevator as far as I can see.
I still have to make sure about that by flying some inverted flying and regular outside loops though.

So, I’m attaching you the link to my latest flying video, and I must admit that my horizontal 8 is still far from perfect. 
https://youtu.be/yrn9C6bW9DY?si=v6xdRPtl0pAWwdUb


A review from a fellow flyer tells me that
my outside loop part is tight and I’m over-rotating the intersection and past vertical before giving down when transitioning from the inside to outside.

Could that be the culprit?
If so, what’s the best way to learn in making outside loop bigger? Doing more lazy 8?

   I am at least a bit skeptical of the diagnosis - but if it is too tight, move the handle less! 

     What I suspect is something else - your control sensitivity is higher on insides than outsides, your neutral may be set wrong, you may have a warp or unintended tweak, your CG may be slightly too far aft, your engine may be running softer on outsides (which can cause both tighter turns AND loss of tension compared to inside).  And if you haven't sealed your hinge lines, go seal your hinge lines, and start over with trim. You may have different flap and elevator rates on "up" and "down" control, which can be partially compensated for by rigging in (in this case) "up" elevator with neutral flap. That's not a real fix to a control geometry/travel rate issue, but might get you by for the time being.

     If you are convinced it is merely a piloting issue - shift your handle to give you more "up" at neutral. Normally you can easily handle pretty big shifts in neutral position in level and inverted flight with little problem, but it it will have a significant effect on the apparent "control pressure" in maneuvers. This will make it harder for you to overly-tighten the transition from "inside" to "outside", which can lead to the top of the outside being too low, forcing you to pull it even tighter to miss at the bottom.

    This sort of thing is why it is so hard to fly stunt successfully, there are a vast number of things it *could* be, and part of the learning curve is to learn enough to figure out whether is it *you*, the airplane (a bunch of small details you may not be aware of), the engine (thousands more things), the air quality, your perceptions, your coaches perception, etc. and pick one of them as "the" problem. This gets better much quicker with experienced help, but no one is *ever* entirely sure what the problem is, and therefore, what the solution might be. You end up building up a series of experiences that allow you to refine it down to specific problem only after very extensive experience of trying things and evaluating the results.

   A big part of the problem is what psychology calls the "unreliable reporter" syndrome, where the person talking about their own problems is among the least objective observer and the most likely to color their interpretation of their own experiences. Same thing here.

      Brett

[EricV]

   I am at least a bit skeptical of the diagnosis - but if it is too tight, move the handle less! 

     What I suspect is something else - your control sensitivity is higher on insides than outsides, your neutral may be set wrong, you may have a warp or unintended tweak, your CG may be slightly too far aft, your engine may be running softer on outsides (which can cause both tighter turns AND loss of tension compared to inside).  And if you haven't sealed your hinge lines, go seal your hinge lines, and start over with trim. You may have different flap and elevator rates on "up" and "down" control, which can be partially compensated for by rigging in (in this case) "up" elevator with neutral flap. That's not a real fix to a control geometry/travel rate issue, but might get you by for the time being.

     If you are convinced it is merely a piloting issue - shift your handle to give you more "up" at neutral. Normally you can easily handle pretty big shifts in neutral position in level and inverted flight with little problem, but it it will have a significant effect on the apparent "control pressure" in maneuvers. This will make it harder for you to overly-tighten the transition from "inside" to "outside", which can lead to the top of the outside being too low, forcing you to pull it even tighter to miss at the bottom.

    This sort of thing is why it is so hard to fly stunt successfully, there are a vast number of things it *could* be, and part of the learning curve is to learn enough to figure out whether is it *you*, the airplane (a bunch of small details you may not be aware of), the engine (thousands more things), the air quality, your perceptions, your coaches perception, etc. and pick one of them as "the" problem. This gets better much quicker with experienced help, but no one is *ever* entirely sure what the problem is, and therefore, what the solution might be. You end up building up a series of experiences that allow you to refine it down to specific problem only after very extensive experience of trying things and evaluating the results.

   A big part of the problem is what psychology calls the "unreliable reporter" syndrome, where the person talking about their own problems is among the least objective observer and the most likely to color their interpretation of their own experiences. Same thing here.

      Brett

Or even simply just starting too far past down wind...
EricV

[Ken Culbertson]

Wind position in the maneuvers is very important.  The intersection of the 8 needs to be as close to dead down wind as possible.  This means starting the inside with a tail wind.  It is not easy.  IMHO watching the video what appears to be happening is the positioning and size of the inside loop.  Ted Fancher suggested an exercise to me to help with exactly what you are experiencing - tightening of the outside loop.  You mentioned the "lazy 8".  He suggested that I move the bottom of the first loop up to about 20 degrees and fly the 8 smaller until I got the intersection centered and the positioning and size of the outside even with the inside.  I was to do 10 consecutive eights this way.  It worked for me but I still have an issue every now and then with the final outside tightening up.  Another exercise that may help get the maneuver centered is to do a series of inverted lazy eights (turning down on the sides instead of up).

None of this is very important until you have addresses all of Brett's comments.  I am assuming here that it is not the plane, but you are at a severe disadvantage in that you don't have an experienced flier (one that knows what a "perfectly" trimmed plane feels like) to fly the plane and tell you what is wrong.  Difference in turning rates is something that is easy to compensate for and you may not even think you are doing it.

Another thought, line tension is not always the same in the pattern and you learn where to expect it and compensate or avoid it.  Each plane is different and this really takes time to develop a feel for.  Without flying the plane, it might be acting perfectly normal.

Ken 

[Dennis Toth]

Two things, first check that the bellcrank is at pushrod connection is straight out at neutral, if it is off it can give just slightly more control in one direction due to the arc path it follows. Second thing to check is the flap to elevator position. Some ships need s slight alignment tweak between flap and elevator. I have had ships that feel like it is kitting around the outside top, dialing back the flap deflections a bit solved this.

Best,  DennisT

[Ty Marcucci]

I  had a similar problem and fixed it by moving the leadouts forward about 1/16".. At that point in the loop, the model is slowing slightly and losing lift, but not actually stalling..

[john e. holliday]

The experts have spoken, but what I see is the inside is too small and the intersection is started too late with you pushing the outside start.    You  also  need to get lower level flight.  Most of all is the handle in neutral on level flights?    

[Brett Buck]

   I couldn't watch the video earlier, but now that I have, the assessment is correct - you are definitely hitting it WAY too hard right as you exit, after having flown a big flat spot. The outside turn clearly "wraps in" on you, that is, it seems like it wants to tighten up after you start. That is *usually* because the control pressure is lighter (i.e. if "floats", or "turns on it's own") than inside, so when you switch from inside pressure to outside pressure, you overshoot,  The question is why.

Any of the guesses above could be the cause. But I am going to guess that you have a flap/elevator rate difference from inside to outside, where you are getting a lot of "down" elevator but not much corresponding "up" flap,  and less "up" elevator with "down" flap. You can *sort of* fix that by rigging in some "up" elevator at neutral flap.

   What I suggest is this: make a template that fits the trailing edge of the wing (minus the flap) and with 0, 10, 20, and 30 degree marks each direction. Make another with the same marks that fits the stabilizer. The reference for the lines is the hinge pin. Then, hold the flap down at 10 degrees, and note how far up the elevator is, repeat with 20 and 30, and then 10, 20, and 30 with the flap down and the elevator up.

    It should probably be 1:1 ratio in both directions, that is, 10 degree flap down gives you 10 degree elevator up, and that 10 degree flap up gives you 10 degrees elevator down, same with 20, same with 30 in each direction. What you might find, however, is that 10 degree flap down gives you less than 10 degrees up elevator, and 10 degree flap up gives you more than 10 degrees elevator down. And progressively further off the more you deflect it. Just for example:

ideal

flap     elevator
-30      +30
-20      +20
-10      +10
0          0
+10     -10
+20     -20
+30     -30

Example (extreme example in the direction yours might be off):

flap     elevator
-30      +20
-20      +15
-10      +8
0          0
+10     -15
+20     -30
+30     -45

   If it is off like described, you can sort of fix it by putting in a bias at 0 flap deflection, that is, maybe 0 flap and +5 elevator (which is extreme...). To actually fix it, you would need to move the elevator horn fore/aft. In the example, the elevator horn would have to shift further forward (towards the hinge line) or be tilted forward to the same effect, then shorten the pushrod to get it back to 0-0.

   Note that an alternate version of this is that the "up" rate and "down"  rate is different at the bellcrank instead of the flap/elevator. A similar test where you move the leadouts to 1/2" "up", measure the flap angle, 1" "up" measure the flap angle , same with down, etc. 1/2" one way should give you 1/2" the other way, of course.

    This sort of thing is the level of "attention to detail" that we always talk about. Stuff like this is far more important that picking just the right airfoil, 2-3 ounces of weight, etc.

     Brett

*I will post a picture of my flap quadrant tool shortly....

   

[Kafin Noe’man]

dialing back the flap deflections a bit solved this

What do yo mean by dialing back the flap deflection?

[Kafin Noe’man]

   If it is off like described, you can sort of fix it by putting in a bias at 0 flap deflection, that is, maybe 0 flap and +5 elevator (which is extreme...)

Is it the same thing as your trimming tips, “Most airplanes of conventional layout need some down elevator at neutral flap to fly best.”?

[Dan McEntee]

  I finally had a chance to watch the video also. After you check out the controls as suggested, I would agree with Doc in that you are really hitting to outside portion of the * too late and too hard. The outside loop is so high it's almost over your head. The inside loop portion is in the ball park, so you need to concentrate on making the outside portion of the 8 the same size.  This isn't anything that the rest of us hasn't had to go through while learning the pattern!! You are still in the early stages where you tend to focus too much on looking at the airplane while  flying and you can't "see" where the airplane is related to the ground and sky.  Go search out the topic in the "At The Handle " section that Ted Fancher made some good comments on the subject. I'll try to add a link here. Somewhere during your learning practice process you will have this "AHA! Moment" where you understand and can execute things better. It just comes with time and practice and after any kind of lay off from flying, it's easy to go back into!! You will get to this point and having a decently trimmed out airplane will be of great benefit because you know the airplane will go where you want and turn like you want it to. You have been at this long enough that you can relate to what Ted has to say in the thread. It's pinned at the top of the "At The Handle " section.
   Keep Flying! Type at you later,
   Dan McEntee

   

[Brett Buck]

What do yo mean by dialing back the flap deflection?

  He means to reduce the ratio of flap movement to elevator movement - that is, change the ratio of flap to elevator from 1:1 (or whatever it is) to 1:2, or something like that.  That will lighten it up on insides AND outsides. That may be an improvement if you are having to switch from heavy pressure on insides to light/no pressure on outsides.

      My suggestion of biasing the elevator "up" as expedient will decrease the load on the "up" turns and increase it on the "down" turns. That is sort of a fix, but also will cause you to have to apply some force to just keep it level. A better fix is to fix the rates as described, that will give you no pressure to hold it level but also even out the pressure between inboard and outboard turns.

      The idea is that you want the rate of turn to be consistent with the control pressure required to deflect the controls. What I think is happening in your case is that to get a given radius turn, it takes way more pressure on insides than outsides, so when you go through the intersection, you have to switch from relatively heavy control pressure on the insides, to nearly no control pressure on the insides.

    To first approximation, the rate of the turn is a function of the elevator *angle* and what you actually do to move the handle is apply a torque or "control pressure" to achieve that angle. If a given turn rate in one direction takes very light pressure and the same turn rate in the other direction takes a lot of pressure, it is very hard to switch from on to the other abruptly.  That's what it looks like is happening above. This may be due to the control setup - which is what I suggest you explore - or a design issue.

     In this case the fact the airplane is sort of a low-wing affair and presumably has different flow over the elevator in inside and outside turns, that may be hard to solve or require a "off-nominal" asymmetrical control setup to correct.

    But start with the simple stuff, it will take you 15 minutes on the bench to figure out what your control system is doing and if there is some asymmetry built in, which I suggest you correct before you start in on any other eyeball or other fixes. This is because you can fiddle around with a bunch of different things, you have to have some idea which one needs a fix, or you just try stuff, it would be easy to just create another problem instead of correcting the root cause. This happens all the time, we are all prone to it to one degree or another (check here for a WHOPPER that I did that lost me 2 seasons of being competitive : https://stunthanger.com/smf/open-forum/my-admittedly-self-indulgent-nats-story/msg641251/#msg641251  ). The engine forum runs on this phenomenon, virtually every "fix" described is stacking one problem on another, many times taking a simple problem with a straightforward fix and stacking on one additional mistake, creating another problem, which is "fixed" with another mistake, etc.

   Brett

   

[EricV]

Just one more thought that popped into my mind reading the other posts, being a profile, you might double check motor alignment... on a profile it can be quite easy to end up with excess down thrust as you tighten a drooping motor down, especially if the lugs have been opened up at all. A little down thrust can be a great thing to fix or prevent a hunt, but too much can really mess with turn rates.

EricV

[Brett Buck]

Just one more thought that popped into my mind reading the other posts, being a profile, you might double check motor alignment... on a profile it can be quite easy to end up with excess down thrust as you tighten a drooping motor down, especially if the lugs have been opened up at all. A little down thrust can be a great thing to fix or prevent a hunt, but too much can really mess with turn rates.

EricV

   That would be step 2 of my plan above. Given this is a profile, I would suspect that little or no consideration was given for control geometry, has classically short control horns, and so any tolerance stackup could easily put in incorrect geometry. And in any case, it should be checked and I am going to go out on a limb and say the idea of checking the rate by measuring it is new to 50+% of the people reading this.   

     Since we are doing the trimming by remote control, I am very concerned about stacking up one problem on top of another. Because even if the control geometry is off, you can "fix" it, sort of,  by intentionally adding some up thrust. Which makes it even tougher to "unwind" the various fixes later.

   This sort of thing is where lack of experienced help, right there at the field, makes it a lot harder, because an experience modeler would take about 30 seconds to work through this and as far off as it seems to be, could probably just eyeball a control asymmetry or thrust line issue and fix it, probably on the spot. We are watching a video and making (educated) guesses and trying to explain ways to diagnose it from 10,000 miles away. So going through and methodically, step-by-step, go through the various possibilities and eliminate them one by one, makes sense to me.

  But sure, absolutely, try to measure the thrust line, too, that is another basic setup step that has probably been skipped or glossed over.

     Brett

[Jim Svitko]

The only thing I can add here is the importance of proper alignment.   It does not take much to throw things off and make for a poorly performing airplane. 

No doubt many modelers have their preferred way of making sure of alignment.  If it works, stay with that.  One of the tools I use is these small levels.  I found them in a hardware store.  I make sure that the engine thrust line, wing chord, and stab are parallel. 

I am not sure I would trust my eyes for this.  It may look straight, but you know how that goes sometimes.

[Ken Culbertson]

This is what I use to do what Brett has suggested.  They are simply printouts of a protractor that I copied from the internet images selections and posted into MS Paint.  You can size them however you like when you print then cut thom out.   I tape them to the fuselage centered on the horn.  It is just as accurate as a $70 angle gauge and disposable.  Whenever I have a new plane I have a starting ratio that I want so I mark it on printout.  As you can learn from the posts below how the flaps relate to the elevator is a big deal.  I have played back you video several times in slow motion and drawn the conclusion that your inside ratio is entirely different than your outside.  To be sure I would need to see an inside the size of your outside and an outside the size of your inside.  A lot of things go into how a plane turns and where the center of rotation is.  Some prefer a plane that turns from the tail.  It would look like the nose leading the tail.  Some like them to do the opposite and have the tail turning faster than the nose.  I prefer the trim in the middle where it looks like the plans is tangent to the arc.  There are many successful designs out there for each.  What you don't want is a plane that leads with the nose inside and the tail outside.  Yours appears to be doing that.  You may be inducing that by the positioning of your intersection, but it is equally likely it is the geometry of your flaps but before I can be sure I need to see a normal outside loop that is not being entered into going past vertical.  There are so many forces working against you by that position that is difficult to see which one is dominant. 

One parting thought.  In getting the controls doing what you want keep in mind that it is the equal turning rate of the plane for equal movement of the handle that is at the heart of all of this, not necessarily equal movement of the control surfaces.

Ken 

[Brett Buck]

One parting thought.  In getting the controls doing what you want keep in mind that it is the equal turning rate of the plane for equal movement of the handle that is at the heart of all of this, not necessarily equal movement of the control surfaces.

   That's sort of true, but I think you want the *pressure* required for a particular turn rate to be equal in both directions, rather than making sure the handle movement gives the same rate. If you get it right those two will be the same, what we are apparently dealing with is a case where it isn't.

   This is just the first step trying to diagnose the issue.I think what you ultimately want is that you get the same turn rate with the same pressure in each direction, that the pressure for a given turn rate (either way) does not have significant discontinuities, and that the pressure for a given amount of line tension is, for lack of a better word, "harmonious". For example, I have flown A LOT of electric planes (and a few IC planes)  that have massive line tension but very light control pressure for a given turn, and it's very difficult to be able to apply the necessary fine and light control pressure while also holding 20 lbs of line tension.

      These sorts of problems are why beginners get so frustrated and why most of the "trainers" are counterproductive. Because beginners don't know how to check out things like control rates and what to do about them, and many of their mentors either don't know either, or they figure it is not worth the effort because the person is just learning to fly and can't tell the difference.

       That video sure looks like beginners can "tell the difference"!  People starting out actually do know what a circle is, but we have, for years, been crippling beginners with combinations of bad airplane, bad engines, and bad advice, and for as much "help" as they get (i.e. "hold your arm straight out and stiff, and just move it up and down", etc), a lot of it is counterproductive. Don't you suppose you, or me, or David Fitzgerald could fly it better? Of course - but why? Because we can overcome problems with the airplane to make respectable-looking flights. Beginners can't, and in some ways they need more "honest" airplanes that you/me/David needs, because they can't overcome the problem as easily. Nor can they figure out what is wrong with it and fix it, at least not without help.

        Brett

[Ken Culbertson]

I apologize for not including pressure.  I was actually referring to your earlier comment on pressure.  I tend to equate them as one and the same because I am one of those lost souls that uses a light weight wide spacing hardpoint handle and fly almost entirely with my fingers.  With too much line tension is nearly impossible to fly that way.  It has to be firm but not excessive.

Ken 

[Dave_Trible]

It's hard to tell without seeing it in person and/or flying the airplane to know if there is something that could be improved with the trim.   Just by what the video shows you are for sure overturning the first loop (inside loop)  then allowing the airplane to climb way too high for the outside portion which is likely where some of your line tension is going away and then your pullout or bottom of the outside is way too high.   You may also be getting too far into the wind from your left which is causing trouble.   As your line tension returns the added pull puts more force into your down elevator adding to the problem of the loop tightening up.   To correct I'd say you should start your intersection and switch from 'up' to 'down' a little sooner,   Not let the outside loop travel higher than the inside was-make both loops at equal height then relax a little as it is coming down the outside portion.   It will take practice if you are tensing up on the outside downward portion.   As I think someone mentioned you may also be waiting just a little late to begin the maneuver-start it a little further to your right with the wind direction so that the airplane isn't going directly into the wind at the top of the outside portion.   I would try to determine if YOU are the problem before I'd start messing too much with the airplane.   You can waste a lot of effort chasing a problem that might not actually solve what you need to conquer.   Once you are flying maneuvers reasonably close to correct and you still have problems you'll find the solution easier to understand.
Just a point of terms;   You keep mentioning "lazy eight".   This is NOT a lazy eight.   This is a HORIZONTAL eight.   The lazy eight has the inside loop on the LEFT not right.   It's not in the pattern and I suggest if you are flying that-don't.   You want to fly only pattern maneuvers in training so that you don't get confused at the wrong time and accidentally go the wrong way and maybe even put the airplane in the ground.   

You are doing well though

Good Luck

Dave

[Doug Moon]

Watch the video of yourself. The inside loops has a nice size to it. The outside is way too small and higher. Practice 3 insides come out inverted then fly inverted for a few laps then 3 outside loops exit upright. Once the insides and the outsides start to look the same your eight will start to come around as well. Make sure the intersection is dead down wind. Even if is just a light breeze it matters. The bottom of the inside loop isn't dead down wind the intersection is dead down wind.

Another thing that can help is always fly your level laps at 4-6'. Start this as soon as you can. This will get you used to the altitude and you will have much more time to complete a maneuver when starting from the 4-6 alt. If you miss it high and come out a 10' who cares, no big deal. But if you are always flying level flight at say 8-10' and you miss is 6' high now your flying in an area of the hemisphere that makes line tensing a little harder to trim out. Flying for 4-6' to the prescribed 45 degrees is the easiest way to get the best trim. I know you're not ready for that but you will be soon if you keep at it. So start working that level flight at the lower alt. It will help you later.

Also while watching you I noticed your walking towards your plane while it is flying. Your right leg is coming around your left leg. You need to flip this as soon as you can. Walk away from the plane. Left leg coming around the right. This will help you keep constant tension and if you need to step back for any reason it's just an easy step. Also this allows you to have your body open in front of plane you while flying instead of your arm flying across your body as the plane flys ahead of you. It doesn't seem like much if anything but once you get this switched it makes maneuver placement much much easier. In many cases that's half the battle when getting even line tension across the entire maneuver.

You're doing great! Keep it up!!

[Crist Rigotti]

Good stuff Doug!

[Doug Moon]

Good stuff Doug!

Thank you. 

The basic stuff is stuff I still work on every time I fly. Good basic fundamentals sets a strong foundation for the rest of it. Without it all the rest is nearly impossible to do with any kind of consistency.

[Brett Buck]

  OK, trying again...

     This *might* very well be a flying technique issue, and maybe the entire issue is just lack of flying skill, no doubt that it could be improved and that a more skilled flier would be able to do a better job. Maybe there are some posture issues, too.   I grant all that. And I am sure it is all well-meant.   

    But if it is what it looks like - a wild mismatch between the inside and outside turn quality/response/pressure, with all the absolutely classic symptoms - we are trying to solve the wrong problem with the "just fly better" advice. At best this leads to learning bad habits and that stunt is really hard. At worst it ends up just getting frustrated and giving up. You should never, ever,  try to "fly around" or "practice out" trim issues unless you have absolutely no other choice. I note that this is not just a problem for beginners - *lots* of people try to do this at all experience levels, and maybe some of them manage pretty good results, but that is definitely the hard way.

   So, whether it falls on deaf ears or not, I think he still needs to *carefully check the control setup* and otherwise systematically, step by step,  make darn sure there is no underlying trim, control setup, or engine run issues before trying to go beat it to death with practice. A few hours of careful work in the shop  can easily avoid wasting time or frustration in the few precious hours you can get in the field.

      Brett

[Ken Culbertson]

   So, whether it falls on deaf ears or not, I think he still needs to *carefully check the control setup* and otherwise systematically, step by step,  make darn sure there is no underlying trim, control setup, or engine run issues before trying to go beat it to death with practice. A few hours of careful work in the shop  can easily avoid wasting time or frustration in the few precious hours you can get in the field.

 

BUT - It is a P-40 profile he is flying.  The ones I have seen do seem to naturally turn tighter outside.  This is purely personal opinion but I would rather see him learning on something different.  I wish there was some way he could get an experienced flier to fly it once.

I hope he takes Doug's advice and posts what it looks like after he masters it.

Ken

[Colin McRae]

BUT - It is a P-40 profile he is flying.

Ken

It's the same Brodak P40 ARF that I have. I don't know if the original author upgraded the controls. The ARF kit has a flap control surface-mounted control horn, and an elevator control surface-mounted control horn. And the kit flap and elevator joiner wires are very undersized causing extreme differential flex in the control surfaces. This causes the model to roll significantly during hard maneuvers.

On my P40, I stiffened the joiner wires which helped my model fly better. But I still have the flap and elevator control surface-mounted control horns so there is still some degree of differential flex between the inner and outer control surfaces. (Can't avoid differential control surface flex with control surface-mounted control horns.

Not sure if this type of issue is contributing to the authors flight experience.

[Howard Rush]

You got some good advice above.  The video was quite helpful, thus getting you better diagnoses than the usual Internet analysis.

The wing isn’t doing what the elevator is asking during outside maneuvers.  Are there holes in the wing bottom?  If there are no obvious anomalies on the wing lower surface, the next thing to check is whether the flaps are taped.  If not, tape them and fly it again.  If the problem remains, heed Brett’s elevator-vs.-flap advice (disregarding his sign convention).  A quick fix would be to bias the elevator up relative to flap position. 

[Steve Helmick]

Watching the video, I counted 4 inside loops prior to the H8. That leads to some binding of the flying lines, and should be avoided. Doing the full pattern only results in two twists, because of the triangles. Some guys choose to start their flight with one reverse twist, so they'll end up with only one twist after the flight.

I'd like to see some outside loops from inverted flight, exiting to upright level flight.

The cramped and high outside per the video will naturally reduce line tension because the model slows, plus gravity.

It looks to me like the model pulls pretty strongly when in upright level flight. I'm wondering if it pulls the same inverted level flight. If not, you need a flap tweek.

Two more points are handle and neutral setting. Absolutely critical. Dedicated lines and handle for each model. I hope you use a "hard point" handle. If not, try one and you'll never go back.
  Steve

 

[Kafin Noe’man]

Hi all,

Thanks a lot for your responses and advice. I really appreciate it—big time!

After reading all the comments above, I immediately checked everything that was mentioned in this thread. The results were that the flap and elevator had equal movement at full up and full down, and their deflection angles were also the same. I tried to set the neutral position as close to 0-0 as possible. The hinge lines are sealed, and the handle spacing is the same for both the up and down lines.

Then, I went flying. My level upright flight felt better. I did the horizontal eight differently this time—entering the outside loop sooner than before—which eliminated the floating sensation. I felt consistent tension throughout the maneuver, and the shape was nice and round, although the outside loop was still smaller than the inside. At least it wasn’t tight and oval-shaped anymore. I still had some hesitation about making it bigger, as I’m still getting used to this plane. It’s not my beater plane, though.

After the flight, I noticed that the elevator was actually slightly down by about 2 or 3 degrees (hard to tell the exact number, but definitely less than 10). This might be a contributing factor, but I think my flying technique played a bigger role. I’ll need more flights to confirm.

Unfortunately, I only managed one flight with this airplane due to bad weather and tall grass at my flying field, so the P40’s trimming process is still a long way to go.

-------

Since my flying field wasn’t in the best condition yesterday, I decided to fly my other plane, the XEBEC (a Japanese-made ARF, 25-engine size).

I think this plane is trimmed better. One of the things I noticed is that the tension remains consistent throughout the flight, even if I make mistakes like flying too high or giving input too early or too late.

Knowing that the plane isn’t going to "betray" me gives me a lot more confidence to fly bigger. By correcting how I performed the horizontal eight—just like I did with my P40—I was able to execute a better figure-eight (big, round, and equal in size for both the inside and outside loops). This plane has crashed several times, and I treat it as my beater, so I have nothing to lose.

Thinking back, I remember experiencing the same floating sensation when flying the horizontal eight with my XEBEC a while ago. But at the time, it didn’t bother me much—probably because my LA25 runs a bit faster and more in a straight 2-2-2, whereas my LA46 is set up in a wet-2 mode.

Too bad I didn’t get any of it recorded, as the downwind was too close to the pit.

In conclusion, I feel like my flying technique has played a bigger role in the issues I’ve experienced so far. So, I’ll keep working on improving my flying while continuing to trim my planes. The more I fly and get comfortable, the better I can understand and see to what Paul Walker explains in his trimming chart articles.


Best,
Kafin

[john e. holliday]

That is good to hear.  Now keep working at it and remember to have fun.

[Ken Culbertson]

Hi all,
Thanks a lot for your responses and advice. I really appreciate it—big time!
Best,
Kafin

I am so glad to read what you just posted.  I came up in the hobby pretty much the same as you are having to but there was no internet or Stunthangar.  I was flying at what we would call today the advanced level without ever practicing flying with anybody better than I was from the age of 14 until I was in my mid 30's.  There isn't a message box big enough to list all of the bad habits I formed.

It seems you are catching on that the things we ask these planes to do is not easy even if it looks easy when done by an expert.  I am glad that you realize that what was happening was a combination of plane and pilot.  Tomorrow, I get to fly my new twin through a full pattern and as soon as I have confirmed that it will, I will be asking one of the best fliers in the US to fly it and tell me what he thinks it needs. I truly wish you had that option.  Keep up the videos and the questions and, like John said HAVE FUN!

Ken