A question occurred to me in relation to Ted's famous (and very interesting to me) experiment.  If it were possible to produce a scaled-up 60-size version of Ted's Tucker in which all else is identical: balsa density, number of dope coats, proportionally higher engine weight, etc. is it likely that the same need for extra weight would occur?

In other words, would the larger control surfaces require sufficiently greater control force so that additional weight might be required, OR, would the greater absolute mass of the larger plane without ballast alone be sufficient to eliminate the problem?  Thanks in advance for replies.  

I am far from an expert in this kind of thing, but I think there is an optimum weight for every plane. I have an old Nobler that was given to me that weighs 52 ounces and is the best cornering plane I have ever flown. It turns extremely tight corners with no bounce and comes out right on line. Even with the Fox 35 that's in it.

I am far from an expert in this kind of thing, but I think there is an optimum weight for every plane. I have an old Nobler that was given to me that weighs 52 ounces and is the best cornering plane I have ever flown. It turns extremely tight corners with no bounce and comes out right on line. Even with the Fox 35 that's in it.

BINGO! That is exactly what I was trying to express in the other (DELETED) thread.  

Brett, Not being an AE I like that squared & cubed thing....  I have experienced it in my past (Glider Competitons) The bigger ships fly better for that application.

Will we see you in Napa on the 6th?

Cheers, Jerry

When you increase the size of an airframe, unless you are building with solid wood, the final density of the skinned and finished airplane will be lower than a smaller ship.  This is a large function of built up construction containing mostly air volume. 

A large plane that is too light may benefit from ballast at the CG...although how much in CL?  I know RC gliders, particularly slope gliders, will benefit from ballast under windy conditions. 

The general rule of lighter is better probably still holds.

Phil

    The fraction of "air/balsa" is constant if you scale everything up (including the wood thicknesses).

    The Tucker experiment definitively showed that lighter was not always better. That doesn't mean that heavier is always better, either. It depends on a multiplicity of things far beyond the overall mass or wing loading.

    Brett

   The fraction of "air/balsa" is constant if you scale everything up (including the wood thicknesses).

    The Tucker experiment definitively showed that lighter was not always better. That doesn't mean that heavier is always better, either. It depends on a multiplicity of things far beyond the overall mass or wing loading.

    Brett

No.  It's not.  If you have a round hole, and increase the diameter by 2x, it has 4x the area but only 2x the perimeter.
  
If the material sizes are increased by the same percentage as the increase of overall scale the density is still going to be reduced.

Phil

    Perhaps, judging as usual, but likely not flying.

     Brett

C'mon Brett.  You can beat me with the Ruffy again.  I added 10oz to the CG and it flies grrrrrrreat!

Ted

p.s.  Actually, I was just joking about the weight.  It's fine at 42 (the Tucker was 34 before adding the lead).  I did, however, make some changes that you'll find salubrious.

C'mon Brett.  You can beat me with the Ruffy again.  I added 10oz to the CG and it flies grrrrrrreat!

Ted

p.s.  Actually, I was just joking about the weight.  It's fine at 42 (the Tucker was 34 before adding the lead).  I did, however, make some changes that you'll find salubrious.

   I will likely not find out this weekend, seeing as how I will be at work 10PM-6AM both days. I supposed I could sleep on the drive up, but I am not sure the other people on 680 would be too happy with me.

   Brett

I don't have the higher math skills that some of you have on this forum but I always thought if you took 34 and added 10 it would be 44. Is this some new math or a form of calculus?

Just poken at ya

   It was 8 ounces added at least when Ted and I were doing it.  I recall different starting and ending numbers.

     Ted was referring to adding 10 OZ to the Ruffy (to "help" me, no doubt, at this weekends contest, while he flies something else). The only number 10 that I recall associated with the Ruffy was the $10 I won when Ted and I both flew it at the NWR.  Some wagering was involved. The recollection is really vague, it came out something like this:

CLASSIC STUNT (15 entries)
1. Brett Buck, 549 (no appearance points)
2. Ted Fancher, 537.5  (17 appearance points)

   I paid for it the next day in real stunt.

    Adding 10 oz to the Ruffy may possibly be less than advantageous, but I am sure my ole buddy wouldn't be steering me wrong here. Alas and alak, we won't know since I am on graves for the weekend and going to contests from 8 to 4 with 2-hour drives each way is not in the plan.

   Seriously, however, given that the Ruffy has no problem deflecting the small control surfaces with the available line tension, it does appear to suffer severely with induced drag due to the low aspect ratio. Adding 25% more induced drag (needed to overcome the weight) doesn't solve any problem the airplane has and exacerbates the one it does have, so not likely to be a good idea. You diagnose and solve the problem you have, and it's not always the same problem, so the solution is not the same every time.

     Brett

I now have personal experience with 10 ounces of dead weight (the battery) with my electric plane. I know for a fact that 10 ounces above or below tether will make the plane roll.

A general reminder here to no one in particular---if we get into controversy, please play nice to avoid having this thread get bounced.  Thanks in advance.

Brett,
Do these planes all tend to have the same problems, or are the problems all over the place?  

  Not all the same. The problems with what I will suggest are "too light" airplanes tend to fall into two categories - inadequate line tension to move the controls, and/or inadequate roll and yaw restoring force. A thrid category of "too light" might also be called "too much flap" and can be solved with trim, so lets forget about that one for this discussion.

   The Tucker is an example of the first problem  - just not enough tension to move the controls far enough. Speeding it up increased the line tension but also increased the control force necessary so it didn't help very much. Let's assume that Ted Fancher and his caddy know how to trim a stunt airplane and would have fixed any underlying trim issues. Adding weight to the airplane and changing nothing else increased the ratio of the line tension to the speed, so the control authority went up with more weight, and the control effort stayed the same, so it came out ahead. In fact, the extra weight allowed the airplane to fly more slowly because it could be slowed down and still have adequate line tension for other reasons, so the end result was much slower lap times and much better cornering. I want to say the last flight without was around 4.6 seconds, and the best flights in the same conditions were around 5.2 with the full 8 ounces. At no point was the lift inadequate to the task, to no harm came from that issue, and it had no problems making it to the top of the circle with a Rustler-Merco 40/Tornado 10-4 3b, so no harm there, either.

   The second issue is that with low line tension, there is less roll/yaw restoring force, particularly roll. Yaw get some passive stability from the aerodynamics (rudder/fin), but there's not much in roll aside from the line tension. That's why tipweight is so critical. If you have a large engine with a large prop, there's a lot of roll and yaw torque variatons, but there's not much line tension available to keep the nose pointed the right direction, nor is there a lot of tolerance for any sort of slightly-off trim condition. Speeding up the airplane does help some depending on the problem but many of the possible disturbances are speed-dependent, too. Changing the line tension at the same speed provides more restoring force and is more robust.

   An example of the latter- two airplanes, both about 585 or so square inches, both with PA65s. They aren't the same design, but not way off. One weighs 54, the other 66 ounces. The first was essentially untrimmable, because the massive amounts of torque, p-factor, etc, cannot be handled with the light line tension available. It may also have the "not enough line tension to move the controls" issue but that doesn't make any difference if it can't be put into proper trim.  The second suffers a bit from weight in hot conditions but is otherwise a solid flier. Both airplanes have stellar vertical performance, a PA65 is still just loafing in either case.

    The first airplane could benefit greatly from several changes - either put on a smaller prop and smaller venturi, and let the PA65 8-stroke at 11,000 rpm, replace the PA65 with a 40VF and run it with the small prop, same effect, or, add ballast (like maybe 6-8 ounces) to increase the line tension without the speed.

   The second airplane would likely benefit from being 4-6 ounces lighter, it would increase the sensitivity to trim errors but eliminate the cornering issues in hot weather. It has also benefitted from a different engine setup that reduces the prop diameter, and removes some of the power variation, but not nearly to the degree that would be needed to fix the first airplane.

    Brett

p.s. in the first case someone might also be tempted to "trim for more line tension". Usually, that is a loser in almost any case, because if you have to manufacture line tension with trim tricks (like lots of rudder offset or excessive tip weight) you get wild variations on the line tension as the speed changes.

Brett,
Thanks kindly for your detailed response to my question.  The concept of dependence on weight for roll recovery is new to me, but seems intuitive once pointed out.  Looks like the BHE approach (Big Honkin' Engine) is not an unmixed blessing.  I find this kind of high-level trim analysis fascinating and informative. 

..... Let's assume that Ted Fancher and his caddy know how to trim a stunt airplane and would have fixed any underlying trim issues......
 

This does seems like a....uhhhhh....fairly reasonable assumption.   

Thanks kindly for your detailed response to my question.  The concept of dependence on weight for roll recovery is new to me, but seems intuitive once pointed out.  Looks like the BHE approach (Big Honkin' Engine) is not an unmixed blessing. 

   It's the dependence on line tension for roll recovery, and if there were some way to make more line tension without adding weight, and without causing the roll and yaw forcing functions to go up too (like lots of rudder offset, engine offset, or tip weight), then you would be set. With very limited power, like Sparky's example, then you might be willing to live with some of the trim issues to create more line tension than you would have otherwise. With overkill power, there's no reason to have to make that compromise since adding weight causes no problems but solves the Netzeband wall and roll restoring force issues. It was not a close call in any way, it was WAY better with more weight.

     Brett

I was talking to Ron and he said they flew their 32 ounce planes at 5.8 -6 second laps with fox 35s in the wind no line tension problems. I find that interesting. My guess is one could say ENGINE OFFSET as they did when that plane was designed.

Sparky,

One of my favorite stunt memories was flying as a junior at the 1959 Nats where watching the Tucker Specials from St Louis was one of "the" best parts.  One of the things that doesn't belong in those memories is any instance of people "timing" laps at the stunt circle.  I've heard others (George Aldrich, for instance) say they flew Fox .35 stunters at six second laps but, with all due credit for their skills, I simply don't buy the numbers.  I remember George flying his replicated Nobler at a VSC at or around six seconds a lap and being unable to complete a pattern, let alone a competitive one.  Billy Werwage won the Walker Cup that year with the Ares/Fox .35 flying smoothly but almost certainly closer to five than six seconds a lap.

In more recent times I remember Bob Gieseke flying 5.5 laps competitively with the Gieseke Nobler.  Big difference from the Tucker, however.  Very small chord flaps... and quite large with very soft corners.  The difference was most everyone was flying that way back then.  That is no longer true.

Bottom line, I've flown stunt competitively since about 1957 and never even considered buying a stop watch to do so until I started attending the Nats regularly in the mid '70s and the whole 5.5 second lap thing surfaced via the Bear.

I believe the real secret to lower lap times isn't light weight as much as it is power train (within reason).  The slowest I ever flew competitive stunt was with the original Trivial Pursuit (650-60 squares at 68 to 70 oz) at the 1992 Nats where it finished second.  It was powered by a VF .40 revving more or less 12K with a 3.25 pitch Bolly.  I still didn't time it, by the way.  Randy Smith, many years later told me he had video tapes he had timed and the lap times were 5.8...which surprised me although I knew they were slower than I flew my previous ST .46 ships with-generally-six pitch props.

Don't get me wrong.  I'm not a fan of "heavy" airplanes.  I do, however, believe that wing loadings lighter than necessary to fly competitively may be more of a problem than a solution.

Ted

Ted - For what it's worth, I flew a Nobler with an ABC Fox 35 at 36 Ounces for a few years. I got away with it, and had reasonable line tension, and it had a great corner and flat pull outs.

I think the reason I got away because of a few unconventional trim options(for Noblers anyways). First, I ran the ABC Fox in a wet 2 cycle, second, I ran rather short lines, these were Tom Morris 19strand .015's I pulled off my Ringmaster that were 57ft eye to eye, and lastly, I sure as heck wasn't running any 5.5 lap, it was more like 5.0. This combination may be why the plane felt very competitive in it's state of trim to me. The other side benefit I believe I will attribute to the short lines, is it gave the feeling of invincibility as far as bottoms went, I never feared pulling out as low as I wanted with that combo. If I wanted to be nuts, it gave the confidence to drill 2ft bottoms on a regular basis if one was so inclined to temp fate.

Near the end of that Noblers duty, it had gained some castor oil ballast, to the tune of 41 ounces. I noted it could be flown "smoother", and wasn't as floaty on landings. The corner wasn't as good, but I think it was more to do with our hot humid florida conditions and the Fox not pulling the weight quite as easily. Looking back, a little tip of the Nitro can was probably in order.

Gave the plane away to a retread pilot who wanted to buy the motor, for just the cost of the Fox. Good thing too... because I heard the plane was so fuel soaked it didn't last very long.

At any rate, I thought the line length/lap time comparison was worth mentioning.
Later,
EricV

An excellent addition to the conversation, Eric.  I couldn't agree more.  "G" forces (another description for line tension) for a given weight and airspeed increase as the radius of rotation increases.  As you note, however, as the radius of rotation decreases so does the resulting lap time.  5.0 at ~59' handle to center is very doable and would be competitive in any game.  I expect you weren't running a 10 X 6EW at a wet two either.

I once flew a Nobler of Don McClave's with a very strong Fox running that way with a lower pitch prop.  Very positive result.

Ted

p.s.  The "nitro" thing is like magic in a bottle when it comes to the emaciating effects of altitude and temperature on air density.  Bumping pitch is often a good idea as well but "demand" the nitro be tipped first when puny thrust is the issue.

I take it you mean "decreases", as evidenced by your next sentence.  Likewise, line tension increases proportional to radius for a given lap time. 

Oooops!

Thank you.

Ted

Just to add fuel to a fire, (or injury to insult) I wonder if the brains trust would give their opnion on Ron Adams Marut Jet stunter from the 60's

It was running a ST 56, and apparently wieghed in at over 100 ounces. If I recall the article on it, He said it flew better than it had any right to.

Thoughts?

I found this on SSW

http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=44955

In, IIRC, 1977 Bob Whitley won the Walker Cup with a Derringer weighing somewhere around 82oz powered by an ST .46. The airplane would turn tight corners and settle on bottoms like it was sitting on a pillow!   Using my carefully calibrated and nurtured "design thief" eyeball I noted the leading edge shaped like a baseball bat and promptly decided a blunt leading edge was worth plagiarizing and pretending it was my idea.

Ted

p.s.  At the 1974 Nats I placed a reasonably competitive 15th in Open flying the Moby Dick...a jet styled, Nobler winged derivative that weighed 64 oz.  While I don't necessarily recommend either extreme example I did pretty much retire my triple beam balance gram scale after those experiences...except for medicinal purposes, of course.

Just reread this after a year or so.  It's a good thread that can stand an encore.

Ted

Yup. I had forgotten (or not noticed) EricV's comment about the shorter lines...confirms what I found out, more or less by accident. A foot shorter lines may feel slower than you'd expect, simply because the increased line tension is more comforting than the quicker lap time is disconcerting.  Steve

I shortened the lines to my Thundergazer a foot and it was so much easier to fly and fly good bottoms with as opposed to flying with the longer lines.  Also, with everything else being equal, the plane will be flying the same speed with the shorter lines, but it has less distance to cover than with the longer lines, which is why the lap times go up without feeling like the plane is flying any faster.

At the risk of contributing to thread drift, here's a pix of Ron Adam's Marute.  I'm pretty sure it was around 70" span and something like 850 squares. The aft fuselage was 4" in dia.  I am also pretty sure it used a Veco 45 - Ron's big Intruders used the ST56 & 60.  I remember the Marute as very attractive design (shape & color scheme) and that it flew very well.  What is notable is that it was NOT Ron's largest nor his heaviest airplane.

Also worth noting from that picture is the narrow chord  way less than full span flaps!!  Another topic for another day inasmuch as probably nobody is going to read this length "OOOOOLD" thread far enough to read it!

Ted

The Olde Girle Has a BIT OF SIDE AREA . Id be thinking IF you Enlarged it . Say the figure was 120 % , If voiticly it was 110% , Due to Mr Renolds Number & somesuch , and longitudeinally & crossways 120 % 

AS IN , Say FUSE is 120 % longer 11% deeper . WING is say 120 % more Span but only 110% on the Chord , Tailplanes 120 straight , and flap chord maybe .  Like it was SPREAD .

The P S S Slope Soarer things often get the cross between what was & a  High A R trip . Stretched n Slimmed . That Fuselage looks near porky , ON THE PLAN .


Get the Picture . Cut out a Cardboard or Foam Sheet one , to access practicality . This is 76 od PSS Foljkerts .

The Stingy Englishmen ( somebody took all there lolly ) whack em outta foam , and throw butchers paper on with watered down PVA .
( please sir , can I have more gruel )

Amazingly Durable in fact .

https://www.pssaonline.co.uk/2005/04/15/power-scale-soaring-part-3/ likum thisum .

Very interesting stuff. It is also interesting that in the original article published in April 1962 American Modeler, Tucker states that a weight of 40oz is what the final version weight in at, very close to what Ted & Brett found.

https://outerzone.co.uk/plan_details.asp?ID=1528

Maybe there is a wing load somewhere around 11- 12oz/ft^2 that for the normal design numbers (basically, Nobler moments and ratios with some tweaking but around those) that gives good performance and line tension.

Best,   DennisT