insight to my findings

[RC Storick]

This thread all started to express how and what I think works for me. This is not a power train war of which drive is better. All the figures and spread sheets are just that numbers on paper and that's a great brain exercise but in the real world may or may not reflect the feelings in responce I seek.

It had been stated in one thread about responsiveness in the aircraft can be a equal in both gas a glow. I agree as long as weight distribution is equal. The notion of a 13 ounce engine at the farthest from the CG will give the same flight feeling as a 6 ounce one at same distance is incorrect and like living in dreamland. As long as CG remains close to the same. The adage of a body in motion tends to stay in motion unless acted upon by a equal and opposite force. It takes more force to leaver 13 than 6. These are all basic principles people want to over look for what ever reason.

The next thing to look at is TE sweep and a swept forward TE will allow the CG to be farther forward than a straight one. Or in reverse swept back the CG would have to move back. Another basic principle.

I by no means am a real life aerodynamic or physicist but I do know about toy airplanes . I can only offer my opinion after building hundreds of diffrent layouts and designs. I use the SWAG method and it works almost every time. As a mechanic I know that I do not know everything and do not claim to.

In one thread I read about checks and balances, this is a good thing and that is the same reason for a test flight. If it worked on paper every time there would be no need for a test and trim flights. We could just do a math equation and a spread sheet analysis and build a world beater. It don't happen like that.

There is a vast amount of talent and knowledgeable people on this forum to draw from. But when a I read some of these threads there are a few here that know everything about everything and if that's the case please answer the question here."what is the meaning of life?" Sure you can try to answer this but it will vary from person to person just as the feel I seek in my toy airplane.

I am lucky (if you call it that) to be able to build quickly and proficiently. This offers me the opportunity to try a vast range of things. For the last 20 years I have been playing follow the leader and now its time to do my own thing. I offer reports on my findings as a tool for others to benefit from the countless hours I spend at the building table. I just wish in 1991 I would have stayed on my path.

There is no one way, there is only the right way and the right way may vary depending on the person.

Sarcasm  Those people who think they know everything are particularly aggravating to those of use who do!

[john e. holliday]

Myself I don't know everything and am still learning.   When I quit learning is when they put this old piece of flesh in the incinerator.

[Derek Barry]

."what is the meaning of life?"

Answer: 42

Derek

[RC Storick]

Answer: 42
Derek

One

[Derek Barry]

On a serious note; Sparky by all means do what makes you happy. If you try something new and it works for you great, if you try something new and it does not work you know not to do it again. I know a lot of really good builder/finisher/fliers that like to tinker and they have a great time doing it. In the end all that really matters is that you're having fun.

Derek

[Tom Niebuhr]

Sparky,

I couldn't agree more. Yes, I have an engineering degree. If everything worked exactly as on paper, there wouldn't be a need for any flight testing. There is a very big need for common sense in engineering.

I am currently working on something very different. I no longer have the $$ to go the Nats and VSC every year, or to practice 4 or 5 days a week. So this is another reason for me to push the envelope. The new airplane will be top secret in Tom's Skunk Works except to say that it will be unique.  I am jumping into electrics with both feet, retracts and all. The learning curve will be very steep, but the challenge will be worth it.

[Dennis Moritz]

Tethered planes are complicated (vastly complicated) aerodynamic machines. Equations describing flight response must always leave factors out. Which is why I think evolving design approaches is the best way to determine what works best. I think it important to note, as well, pilots can differ vastly in what they like. Sparky's point about the mass up front favoring electric has been made before. Less mass front and back, easier to turn, less momentum. But I think, as in many things controline stunt, the answer is more complicated than it first appears. If a good stunt turn (or corner) was only a question of less momentum  at the ends of the fues, combat plane configurations would dominate this sport. They do not. A certain amount of resistance to a turn (a minimum amount of momentum?) is needed to smooth maneuvers out, making the maneuvers appear better formed. I think it interesting that some who fly electric have decided to move the cg forward of the cg location favored for a given design when using IC. Increasing momentum numbers fore and aft and perhaps improving other factors we have not identified here.

[Will Hinton]

Quote from Sparky: Well Now my eyes have opened. Will I ever win the NATS? Doubtful but my planes will be more fun for me to fly.

And THAT, my friend, is how you spell success!!
Will

P.S. Derek left off the .0072135 in his answer to what is life.

[Eric Viglione]

This guy says it's 1.  
EricV

Answer: 42

Derek

[RandySmith]

 That works for you and is great !  

There is more that need to said ,Just for reader's  info, a  12.5 to 14 ounce battery pack (which most all are using) in the same place or farther forward,vs. a 6 ounce fuel tank with fuel ( 5 oz plus 1 for tank)  is a whopping amount of difference and is also concentrated weight at the  EXACT same place in stunt ships, or in the battery case can go even farther forward, So this is info you will have to take into consideration when thinking about this, you cannot ignore this weight either, that one item is a 6.5 to 8 ounce difference, and is much more than an equivalent 8.4 ounce IC engine vs, a more farther foward 6.5 ounce EC .
Just facts for thought if anyone wants to use them.

"There is no one way, there is only the right way and the right way may vary depending on the person. "    Agree   

Regards
Randy

meaning if life =   mass - appropriated    

[RC Storick]

Just facts for thought if anyone wants to use them.

How much concentrated weight is 2 inches behind the spinner for each? Its the same tune over and over only it's not the same. It would be the same if you put a fox 35 in the nose and used 14oz of fuel but we are not talking about a fox 35.

Or if I was using a 10 ounce motor. I am not. I am using something that is the same weight as a fox .35. and a battery that weighs 12.5. Next plane is a AXI 2826/12 at 6.5 and a 10 ounce battery. Dropping another 2.5 off the nose and to balance I will need to drop 1.5 off the tail. That drops my total gross weight a whopping four ounces. Keeping in line with my last plane. However I am changing it up some to lose some more weight. Almost the weight of a motor.

After I wrote this last edit I think that's were some interpretation of mine is lost. Measure back 2 inches from the spinner back plate and tell me which set up has the highest amount of concentrated weight

When I built my 48 oz piped .65 viper 8 it took me a few try's to do so. I would like to see a 660 inch 50 ounce plane for my next one. It's hard to do but that's what makes it a challenge.

[RandySmith]

"Next plane is a AXI 2826/12 at 6.5 and a 10 ounce battery. Dropping another 2.5 off the nose and to balance I will need to drop 1.5 off the tail. That drops my total gross weight a whopping four ounces. "

That is going to help you tremendously in the next plane! that much weight lost will be huge .

If you really want to know the numbers I will be happy to run them on just one component , the old and new weights ofthe moment of inertia .

   Only the battery            Your old battery                       vs.                                Your new battery
            Moment (contribution to CG), inch-oz   96.88               Moment (contribution to CG), inch-oz   81.38         
            Moment of inertia about CG, inch2-ozm   750.78               Moment of inertia about CG, inch2-ozm   630.66


                                                  The second one, below,  is average of 5 ounces of fuel  vs  the old battery         



   Fuel average of 5 ounces                 battery 12.5 ounce version   
   39      vs. >         Moment (contribution to CG), inch-oz   98.81
   253.5      vs. >         Moment of inertia about CG, inch2-ozm   765.8

[RC Storick]

Maybe I am stupid I don't know. But I am not sure what this exercise is trying to prove.

All I know is that 2 inches behind the spinner 6.5 ounce is less than 11.5. that's 5 ounces less. 2 inches behind the spinner where it counts most at the farthest away from the CG. These figures are not imaginary they are indisputable. Trust me I can feel them in flight. Once again I am not saying electric is the way to go they have issues too but 2 inches behind the spinner they are lighter in my set up.

Just as I can on the dyno the numbers can be manipulated to represent anything. I am not after numbers I am after a specific feel.

This experiment was done on Viper 8.

[Douglas Ames]

You can get the same CG with IC vs. EL, but Polar Moments of Inertia might be very different. Keeping the wing loading in check is another big factor. That's what I got out of the last thread.

Year ago we added Hush kits (muffled exhaust) to our aging 727's (A'A Airlines) and had to add ballast on the Radome bulkhead to keep the CG within range. Also there is ballast weight on the tips of our 757's with winglets due to the verticle surface area (increased PMI for gust dampening)

[Spell Check] ...it's easy!

[RC Storick]

You can get the same CG with IC vs. EL, but Polar Moments of Inertia might be very different. Keeping the wing loading in check is another big factor. That's what I got out of the last thread.

Year ago we added Hush kits (muffled exhaust) to our aging 727's (A'A Airlines) and had to add ballast on the Radome bulkhead to keep the CG within range. Also there is ballast weight on the tips of our 757's with winglets due to the verticle surface area (increased PMI for gust dampening)

[Spell Check] ...it's easy!

Did this change the feel in responsiveness? Of coarse its fly by wire and I have no clue if the feeling is transmitted back to the yoke.

EDIT: for those who do not understand the term fly by wire. This does not mean they are attached to cables. It means the Yoke/stick is actuating a potentiometer signaling a computer input to the hydraulic actuator. I would think much would be lost in the feel but never having flown one (or for that fact any)I have no clue.

[Eric Viglione]

OK, I promised myself I was not going to add to any potential strife in this thread, but I'm thinking maybe I can actually help calm things down a little with what I see as lack of communication.

Sparky, I think what some of us are saying but you're not hearing can be helped by some pictures.

You can put a 1 ounce motor out on the end of a 30 inch nose moment if you want to make an extreme example. All some of are saying is it's potato / potato when you take the moments into account. You seem to ignore comments that place the front mount ELC motor in a different place than the IC motor. The IC C/G is based on balancing a motor on a wire to see where it's C/G was in relation to the bolts, and it balanced towards the front 2 holes because of the crankshaft counterweight and rear bearings I think. But, the front mount ELC puts most of it's weight on the vertical front mount and it's C/G might be slightly behind the mount with the motor hanging back there. See pic's.

I think it would be an interesting experiment if you had potential to rear mount your ELC motor in the same plane and see if you could feel a difference.

Maybe I am stupid I don't know. But I am not sure what this exercise is trying to prove.

All I know is that 2 inches behind the spinner 6.5 ounce is less than 11.5. that's 5 ounces less. 2 inches behind the spinner where it counts most at the farthest away from the CG. These figures are not imaginary they are indisputable. Trust me I can feel them in flight. Once again I am not saying electric is the way to go they have issues too but 2 inches behind the spinner they are lighter in my set up.

Just as I can on the dyno the numbers can be manipulated to represent anything. I am not after numbers I am after a specific feel.

This experiment was done on Viper 8.

[RandySmith]

   Only the battery            Your old battery                       vs.                                Your new battery
            Moment (contribution to CG), inch-oz   96.88               Moment (contribution to CG), inch-oz   81.38         
            Moment of inertia about CG, inch2-ozm   750.78               Moment of inertia about CG, inch2-ozm   630.66


What your after is a lower moment of inertia..ie  lower weight  as in the above numbers are better for you with the 81.66 vs 96.88
and   630.66 vs   750.78    this is your current  battery  vs you new battery.

Now weight is not but a part of the equation, you have to look at where the weight is and how much it affects the plane,CG,Feel ,what happens when G forces are acted upon the  parts in your plane....whatever you want to use
The graph is a good way to find out how much the 2 different battery weights affect the moment of inertia.
You can do the same thing by plugging in 2 different weight electric motors,  2 different weight  ESCs, different timers, spinners, props, ie everything you could select from to run in your plane, including different mounts .

Randy

[RC Storick]

I think it would be an interesting experiment if you had potential to rear mount your ELC motor in the same plane and see if you could feel a difference.

Interesting you would say that as it makes no difference 2 inches is still 2 inches. Also the Viper was mounted like that.

2 inches back from the back plate of the spinner still weighs 6.5 for one and 11.5 for the other. Why is this so hard to grasp? Viper 8 same plane same spinner local. 2 diffrent set ups IC/ele. I felt the difference big time. And I moved the CG 1/2 forward on the electric plane. It still had a better feel.

All the speculation and Pi radius square and spread sheets can not convince me any diffrent how it felt.

My new electric airplane still has some trim issues and if I don't get them sorted out before the NATS I will fall back to my Continental but this does not change my mind on feel.

[john e. holliday]

Well Sparky I hope you get it working before the NATS.   As I've stated before, "What works for one may not work for another".   Now go show them that hard work is what pays off.  Also pulling for our local guy, Dave Trible, that he will have a great NATS.   Be neat  weeing you two fight it out for first and second.   And don't say it can't be done.

[RandySmith]

This is pretty simple, the program is just a  **tool **  you can use if you find any information that you would like to use, know, or if it would help you in calculating your specific moments of inertia, which are the forces you feel  acting on your plane.
 You have a computer, the program can be plugged into it, and used, you can use it to find how the weights, and where they are will affect your plane, you can use these on only EC parts, or any other part. You can also use it on the other end of the plane by plugging in the stab, elevator, rudder, adjustable hardware, removable hardware, or any other part of a plane.
You do not even have to have Excel , the  FREE   Spreadsheet program in Open Office runs it perfectly.

So anyone that finds a use for it ,can run and use it, no one has to use it, just do what you like. But please keep in mind inertia affects everything, of all weights, nothing is immune.

Randy

[RandySmith]

Eric was just simply saying basically  this, take a 6 ounce EC motor mount it right on the nose ring, then remount the same motor in the same plane back 4 inches from the nose ring by extending the shaft... the moment of inertia will be way different, the feel of the plane will also be way different, same EC motor, same weight.
And in comparing two types of power plants they need to be plugged in by the point of their CG weight, the EC motor is center of the motor or slightly forward, the IC motor is much more rearward because the bulk of the weight of the IC motor (CG of the part ,Motor) is much farther back toward the CG of the plane and away from the nose ring.

Simply said 2 planes with the same nose length, that have an IC and a EC motor set at say 10 inches will have 2 different points when the CG of the motors are calculated.
You can even have them weigh exactly the same..ie IC motor weighs 7.9 ounces and the EC motor weighs 7.9 ounces, the EC motor will have a more forward point that the weight is concentrated in.


So when you design your next plane, and are using lighter parts, but you want the feel to be the same, and you want to know  where to locate the parts...what the nose moment should be, you can use this to find out.

Randy

[Howard Rush]

As I've stated before, "What works for one may not work for another".  

This Newton stuff pretty much works the same for everybody.

[BillLee]

This Newton stuff pretty much works the same for everybody.

None so blind as those who will not see.

[RC Storick]

None so blind as those who will not see.

Yup your right! I have done it in a practical application not on paper. The paper does not feel like anything but paper.

The title of this thread is incite on MY findings done on the same airplane with both power systems. Viper 8 which led me to my next project. The title of the thread reflects actual real time finding not hypothetical charts,figures or formulas. The best test is build one and see if you can feel the difference and if not stay the course.

[RandySmith]

Here is just one thing you could do that you may find helpful with the program, If you want to build a another new stuntship with the new light weight battery and AXI motor and you need to know about the weights to CG you could do this. Notice the light battery is moved forward 1/2 inch and the motor 1 inch, this give the same number,  (contribution to the CG).


                                                 old setup                                                                                            new setup
            Moment (contribution to CG), inch-oz   168.75               Moment (contribution to CG), inch-oz   168.68         
            Moment of inertia about CG, inch2-ozm   1628.13               Moment of inertia about CG, inch2-ozm   1803.85         
                                          

Yes the moment of inertia is different, but that is where trimming and tweeking come in.

Randy

[BillLee]

Yup your right! I have done it in a practical application not on paper. The paper does not feel like anything but paper.

The title of this thread is incite on MY findings done on the same airplane with both power systems. Viper 8 which led me to my next project. The title of the thread reflects actual real time finding not hypothetical charts,figures or formulas. The best test is build one and see if you can feel the difference and if not stay the course.

Definition of INCITE
: to move to action : stir up : spur on : urge on
Synonyms
    abet, brew, ferment, foment, instigate, pick, provoke, raise, stir (up), whip (up), set in motion

Definition of INSIGHT
1: the power or act of seeing into a situation : penetration
2: the act or result of apprehending the inner nature of things or of seeing intuitively
Synonyms
    discernment, wisdom, perception, perceptiveness, perceptivity, sagaciousness, sagacity, sageness, sapience

Which is it, Sparky, that you are really trying to do? I suspect you THINK the latter when, in fact, you have achieved the former.

I have watched these threads with interest, not because I wish to go out and build a stunt ship (far be it from me!) . But I am, as are MANY here, interested in the WHY things are what they appear to be. You experience a "feel". Why? What causes it? How to use the physics that you "feel" to produce the same results for others?  And, again, for MANY of us, intuition or arm-waving explanations are not enough.

As I re-read these threads, I hope to find that NOBODY is calling you down for what you "feel". Everyone is saying "That's great, Sparky, come on down and fly with us and have fun!". I think most all have attempted to be civil with you. However, it behooves you to allow the scientists and engineers among us to question what you "feel" in an attempt to explain the "WHY" of it. Nobody is saying that your empirical evidence is wrong, or that what you "feel" is not actually there, but trying to rationalize it for understanding.

Regards,

Bill

[ptg]

?!

[BillLee]

?!

Phil, the original title was "incite to my findings" or "incite on my findings" (Not sure which exactly since Sparky changed it after I made my post above.)

Bill

[RC Storick]

Phil, the original title was "incite to my findings" or "incite on my findings" (Not sure which exactly since Sparky changed it after I made my post above.)

Bill

It don't matter!