Trimming Problem

[Guilherme Souza]

Dear All

I'm flying Chupin (Brazil model  all demountable) Electric
I'm using Fiorotti´s timer , Hyperion 740 kv 5S battery 2700mhs (zippy and Fullymax)

What is happening ?

In all maneuvers I feel low tension in up part (top of looping for example) , but in inverse looping , second part of triangle I fell very very low tension .
Sometimes I need to pull the lines .

Some one could help me ?
thank you in advance

Guil 

[MikeyPratt]

Guil,
It sounds like you have to 2 (or) 3 things that need some adjustment, try adding a little tip weight, move leadout back, or a wing warp (most important issue). 

I’m sure you had a helper make sure the wings were level upright and inverted, but have another set of eyes look at it the next time you out flying.  Keep the model at four feet in both directions and have the helper watch carefully.  If the wing is low upright and high inverted, it has a warp.  Correct the warp or adjust the flap to level the model in both directions. 

Once you have the wing flying level now try to add tip weight until the the outboard wing drops in a hard corner, now take a little out and refly the model making sure the wing drop is not present.

If the model still has less line tension at or above 45, move the leadouts to the rear 1/8” at a time and refly the model.  It’s doughtful you will have to move the leadout more than a 1/4” than what the designer showed on the plans, but maybe.  Another way is to watch the position of the landing gear in flight, if the inboard tire is slightly ahead of the outboard wheel (1/4 of the wheel) this is a good indication that it’s pretty close (assuming the model sets level on the ground).

Good luck and let us know how it works out,
Mikey 

[Guilherme Souza]

Guil,
It sounds like you have to 2 (or) 3 things that need some adjustment, try adding a little tip weight, move leadout back, or a wing warp (most important issue). 

I'm sure you had a helper make sure the wings were level upright and inverted, but have another set of eyes look at it the next time you out flying.  Keep the model at four feet in both directions and have the helper watch carefully.  If the wing is low upright and high inverted, it has a warp.  Correct the warp or adjust the flap to level the model in both directions. 

Once you have the wing flying level now try to add tip weight until the the outboard wing drops in a hard corner, now take a little out and re fly the model making sure the wing drop is not present.

If the model still has less line tension at or above 45, move the leadouts to the rear 1/8” at a time and re fly the model.  It's doughtful you will have to move the leadout more than a 1/4” than what the designer showed on the plans, but maybe.  Another way is to watch the position of the landing gear in flight, if the inboard tire is slightly ahead of the outboard wheel (1/4 of the wheel) this is a good indication that it’s pretty close (assuming the model sets level on the ground).

Good luck and let us know how it works out,
Mikey

Thank you Mikey
Today I put my motor a little outside .
Tomorrow morning I will  do more flights  ( I have 5 battery's so 5 flights )
I will do the first flight and check if the motor outside had some difference  if not,  the second flight I will move back my leadouts , they are all forward (front)
Third flight tip weight

thank you a lot

Guil

[Mike Haverly]

Are you sure there is no warp?  Make sure it is not tail heavy.

[Guilherme Souza]

Are you sure there is no warp?  Make sure it is not tail heavy.

My big problem Mike is I fly alone .
I can record my flight and watch after.

Maybe some flap warp
One day I will do the system that let us adjust the flaps without tweaks the flaps .

thank you

[Target]

It sounds like the plane is rolling outboard in upright flight and rolling in on inverted flight? If so, it sounds like you might have a warp or need a flap tweek.
Good luck tomorrow.

[Massimo Rimoldi]

Hi.
The poor tension of the lines in the maneuvers can be caused by many factors and often some together.
Personally I suggest you read here: https://stunthanger.com/smf/open-forum/functions-of-trim-adjustments/msg66267/#msg66267
If you follow the directions you will find yourself in a starting situation without any particular anomalies.
You can find a lot of advice and opinions, but it is difficult for anyone to help you solve the problem without having a more detailed idea of the situation.
Without a VERY precise description of ALL the symptoms, no doctor can heal a patient without a good dose of luck.
Make sure the wings are horizontal in straight and reverse flight, ask a friend to look at your flight for a few minutes if you have difficulty doing it yourself.
If you still can not solve the problem, try to provide some information about the current trim condition of your model.

Massimo

[MikeyPratt]

Thank you Mikey
Today I put my motor a little outside .
Tomorrow morning I will  do more flights  ( I have 5 battery's so 5 flights )
I will do the first flight and check if the motor outside had some difference  if not,  the second flight I will move back my leadouts , they are all forward (front)
Third flight tip weight

thank you a lot

Guil
[/quot

Guil,
Lots of good help and suggestions here.  The outthrust should help but I think it's still a warp and/or a tip weight and leadout position from you posting.  I know it's very hard to know exactly what's going on with out seeing the model fly but we all want to help you. 

I have a few more questions for you,
Are you running a right hand prop on the motor?
What is the glide like when the motor stops?  Does the model climb, stay the same or drive?  What you are looking for is a smooth steady glide till just about touch down for a landing.
On outside loops & squares is the model loose (week line tension)?

Again, let us know what's happening with your model,
Mikey

[Guilherme Souza]

Thank you Mikey
Today I put my motor a little outside .
Tomorrow morning I will  do more flights  ( I have 5 battery's so 5 flights )
I will do the first flight and check if the motor outside had some difference  if not,  the second flight I will move back my leadouts , they are all forward (front)
Third flight tip weight

thank you a lot

[/quot

Guil,
Lots of good help and suggestions here.  The outthrust should help but I think it's still a warp and/or a tip weight and leadout position from you posting.  I know it's very hard to know exactly what's going on with out seeing the model fly but we all want to help you. 

I have a few more questions for you,
Are you running a right hand prop on the motor?
What is the glide like when the motor stops?  Does the model climb, stay the same or drive?  What you are looking for is a smooth steady glide till just about touch down for a landing.
On outside loops & squares is the model loose (week line tension)?

Again, let us know what's happening with your model,
Mikey

Hello Mickey

Today I did 5 flights
1  Flight  - Put the motor a little outside .  Very little difference , in this flight I increase rpm in Fiorotti´s timer . I´m using 3 blade 12x5 prop carbon prop

2 Flight - Add tip weight 10 gr and did a small twist in flaps , because I can see when I´m flying some part of my wing ( the flaps must be small twist because if was right I could not see this part)
Good flight tension increase a lot .

3 Flight - move my leadouts 1/8 back the problem come back  and need to stop my flight soon , I was using a repaired battery but one cell get very hot .

4 Flight - return the leadout to full position  (in front ) - the tension come back again not like flight 2 but better

5 flight - Just flight did all square maneuvers and a lot of hourglass

I checked that my plane is getting slow when climbing to hourglass

Answering your questions

Normal prop - Carbon prop 12x5 tri blade , Igor style .
When motor  stop the gllide is normal , did not have up or down movement .
and yes , Outside and square loopings I have weak tension .

thank you

Guil

PS : Sorry my English

[Guilherme Souza]

Hello Mickey

Today I did 5 flights
1  Flight  - Put the motor a little outside .  Very little difference , in this flight I increase rpm in Fiorotti�s timer . I�m using 3 blade 12x5 prop carbon prop

2 Flight - Add tip weight 10 gr and did a small twist in flaps , because I can see when I�m flying some part of my wing ( the flaps must be small twist because if was right I could not see this part)
Good flight tension increase a lot .

3 Flight - move my leadouts 1/8 back the problem come back  and need to stop my flight soon , I was using a repaired battery but one cell get very hot .

4 Flight - return the leadout to full position  (in front ) - the tension come back again not like flight 2 but better

5 flight - Just flight did all square maneuvers and a lot of hourglass

I checked that my plane is getting slow when climbing to hourglass

Answering your questions

Normal prop - Carbon prop 12x5 tri blade , Igor style .
When motor  stop the gllide is normal , did not have up or down movement .
and yes , Outside and square loopings I have weak tension .

thank you

Guil

PS : Sorry my English

My plane

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[Steve Helmick]

My experience is that thrust offset does little for line tension, BUT it vastly speeds up regaining line tension after the lines have gone slack. As that improves the chance of keeping your plane from becoming splinters, that is a very good thing.

I think I would also add tip weight (for more safety), adjust the warps or flap tweeks, and then start reducing tip weight. It is harder to trim a broken airplane, and usually not much easier to trim a repaired one!

While I'm not an electric guy, I don't believe I would be doing "all squares and a lot of hourglasses" with an electric, because those will drain the battery faster. I think you'd be good until the ESC says it's time to shut down the flight early (because of battery drain limit) and that can be sudden and badly timed (resulting in a crash). Maybe an electrified guy will comment on that? I have seen them shut down early, and as I recall, it was quite sudden and not much of a warning, like a good glow engine gives. But it was a few years ago, and memory fades. If it had been mine, I probably would have a better recollection?    Steve

[MikeyPratt]

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Hi Guil,
From the photos, it's a nice looking model and well built.  OK now that we have a better base line I think we are starting to get somewhere.  I would suggest changing the flight time to a short 2 minute flight to keep from risking the model until we have it trimmed properly.  It can't be to far off if you doing many of the maneuvers in the pattern.  At this point I would try adding more tip weight and see what we get.  If that helps, move the leadout forward and fly again.  It would be good to seal the hinge lines with clear tape, Fastcall, 3M, or something similar.   That should make a big difference in the flight trim.  As a note I seal the hinge lines before flying the model the first time.

The one thing I know about electric systems there are many ways to set then up.  With loosing power in the climb up to the hourglass is a set up problem.  Turn off the function of the timer until the  model is trimmed and go back to a 2 blade prop for now, we don't need the headaches at this point.

Let me know how the above suggestions work,

Mikey

[Fred Underwood]

Agree that you should go through the trim process and suggestions first, but a few comments about the timer.

I assume a V4.4 programmed by Jeti Box?

Are you sure of the sensor mount and install?  Is it leveled and calibrated properly, sensor not inverted?  Where is it in the plane?

What are the settings for functions 4, 5, 6 and 7?

Does the propeller sound indicate that the rpm is going up, down, or stable in the maneuvers?

As suggested, it is easy to turn 4 - 7 off or to 0 and take the accelerometer out of the equation.  Also, it may be more efficient for the process to fly shorter flights and a couple of maneuvers that demonstrate the problems.  You could get say 10 short flights, not full patterns, and make adjustments.

Nice airplane!

[Joe Ed Pederson]

Last week I discovered Paul Walker's articles on trimming stunt models in PAMPA's magazine "Stunt News."  The articles are simply titled "Flying" in the index at the front of each issue.  The articles start in the 2014 March/April issue of Stunt News and run through the 2015 January/February issue of Stunt News.  He has a flow chart for setting basic trim and advanced trim.  The flow chart tells you where you start trimming and how subsequent changes to trim can effect earlier trim and where to start over in the flow chart if later trim changes cause problems that had been solved earlier.   I consider these articles alone to have been worth the price of electronic membership in PAMPA.

A few weeks ago I joined PAMPA for $28.00 (US).   I would imagine the price is the same world-wide since there is no publishing and postal expense.  Membership with print copies of Stunt News is $58.00 (US).  For the electronics subscription you can down load issues of Stunt News back to 2009.

Hope this helps.
Joe Ed

[Steve Helmick]

A lot of Paul's technical, trimming and flying articles are available on Flying Lines. I believe they are archived back a good many years if you want to dig a bit. You can start here http://flyinglines.org/walkerstunt.html and it's free, although donations are appreciated.  Steve

Edit: I am wondering about wing asymmetry. If it is equal panels inboard & outboard, then the 10 g. added tipweight is very little, almost insignificant. Better to start with too much and reduce if the outboard tip dips on hard corners.   

[Guilherme Souza]

Dear  all

Today I did more 4 flights

I reduce my lines 50 cm  (half meter almost 19 inch's) and did a 2 min flight , but this time I record the  flight .
So ........ I was flying very slow , after reducing lines the lap times was 5,6 Sec .

the second flight I change the prop , I was using  12x5 tri blade prop and change to 12x6 2 blade prop .
The flight was better , the lap time increase to 5,2 / 5,3 and the tension problens  finish . ( OK  I still have tension problens but with higher speed  I fell less)
Third flight was 4 minutes , a lot of triangles and hourglass and ok
4th flight 4 minutes  a little more wind   almost all pattern and ok

Now I have other problem  BATTERY

what do I should do to save more power  ?

Use low pitch prop (like 12x5 ) and more RPM or  use larger prop 13x6 ?

Here in Brazil TP is very very , very expensive . So I use Zippy compact battery's .

thank you

Guil

[Mike Haverly]

Active timers use more energy.  I think Fred switched to a 6S set-up for that reason.  Those of us using Igor's system use 6S and it is adequate but not way too much.  Did you say how much you have left at the end of your flight? 

[Fred Underwood]

I started with 5s 2700 Zippy batteries and 64' lines, eyelet to eyelet, and KR timer.  I quickly learned that many used 6s pack for more total watts, and if active timers, for more potential top rpm/head room.  I switched t 6s packs and 66.5' lines and had battery to spare.

With an active timer, I fly slower lap times and use a little boost, more braking.  Net result is about the same battery use, perhaps a bit less than with essentially fixed rpm.

You may have to go to 6s, or shorten lines a bit more since 6s may not be economically practical.  TP may have a little more amps therefore watts, but not enough to make the difference.  6s is about 16% more amps than 5s if I understand correctly.

I had reasonable battery usage with Xoar 12x5 2 blade, but 700 kv motor and 6s pack.  I found 12x6 more amperage conservative on 5s pack and that kv range.

What plane weight, line length, and timer settings?

[Guilherme Souza]

I started with 5s 2700 Zippy batteries and 64' lines, eyelet to eyelet, and KR timer.  I quickly learned that many used 6s pack for more total watts, and if active timers, for more potential top rpm/head room.  I switched t 6s packs and 66.5' lines and had battery to spare.

With an active timer, I fly slower lap times and use a little boost, more braking.  Net result is about the same battery use, perhaps a bit less than with essentially fixed rpm.

You may have to go to 6s, or shorten lines a bit more since 6s may not be economically practical.  TP may have a little more amps therefore watts, but not enough to make the difference.  6s is about 16% more amps than 5s if I understand correctly.

I had reasonable battery usage with Xoar 12x5 2 blade, but 700 kv motor and 6s pack.  I found 12x6 more amperage conservative on 5s pack and that kv range.

What plane weight, line length, and timer settings?

Hello Fred

My plane is heavy   2030 gr 71 oz  with battery and  19 meters /62 ft the lines
Battery is Zippy compact 5S 2700 mha
Propeller  2 blade 12x6 carbon Dynan
Fiorotti timer
rpm parameter is 96
nose up 11 70 %
Ukrainian lines

Using Hyperion meter my battery finish the 4 minute flight with 25%  .
 

Thank you
Guil     

[Fred Underwood]

You may have difficulty with enough watts in the battery for that weight plane, but the short lines may help. 

I still don't understand your settings. Nose up is setting 4 and I see that.  What is setting 5, 6, and 7?

What is the actual rpm, not the setting?

The reason for 6 cells it total watts available and for rpm boost.  Also, the 6 cell 2700s seem to have better weight than going to 5 cells with higher amps.

What ESC?  Do you have datalogging?

[Mike Haverly]

Using Hyperion meter my battery finish the 4 minute flight with 25%  .

Flight time for a complete pattern is around 5 min. 15 sec.  According to this info. you won't make it, you need 6 cells.

[Guilherme Souza]

Good morning ALL

I did a Lot of tests and I Will use 12x6 2 Blade carbon prop.

I measure the Amps, Watts and Trust
In static test with this prop I have more Trust with low amps.

Today is a Holliday here só I Will fly today.
After flight I Tell what happened.

Thank you

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[Guilherme Souza]

Using Hyperion meter my battery finish the 4 minute flight with 25%  .

Flight time for a complete pattern is around 5 min. 15 sec.  According to this info. you won't make it, you need 6 cells.

Hi Mark

After do some propeller changes ( come back to 13*6 carbon prop) Im using 2000 / 2050 tô one flight Full pattern.
My lap time is fast 5.0 sec I can reduce and save battery. 5.2 is my ideal.

My plane is heavy 2000 Gr almost 70 Oz só I need a big prop.

After tweaks the Flap the problem of tension decrease a Lot . Now Im confortable .

Thank you
Guil


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