Not model RRing, but impressive modeling

"Geezer" wrote

The models *have* to be overpowered.

After all, where is anyone going to find the scale-length concrete-paved runway that would be required to get an accurately power-loaded model B-29 off of the runway? (The WW2 Tinian runway was 6,000 feet in length. If the model were built to 1/8th scale for instance -yielding a 17.6 foot wingspan- the scale runway would have to be 750 feet long...)

And there's another aerodynamic problem as well: it's known as "scale effect", and it means that a model-sized wing is considerably less efficient that it's full-sized big brother. So you have to drag it through the air at a proportionally higher speed to get the same amount of lift that the larger wing would get at much lower airspeeds.

Taken together, these factors mean that even if you had an accurately power-loaded model of practically *any* aircraft, and a scale length runway to fly it from, there's a very good chance that it would never be able to get off of the ground under it's own power!

All modelling suffers from either a power or speed imbalance to the prototype. It's not entirely uncommon for model trains to exhibit these symptoms as well. Voltage and gearing frequently make them start, travel and stop much faster than their prototypes.

Cheers, John

"John Fraser" wrote in news:48187a1e$0$4061$ snipped-for-privacy@news.aliant.net:

Not to mention the pure lack of mass compared to the prototype. There's just not enough mass behind a model engine (in railroading scales) to push the locomotive like what happens on the prototype.

Sometimes you see the effect in G gauge, but rarely in HO.

Puckdropper

Those problems can be got around in model railways by fitting sensible gearing and weighting as generally rigid structures hold our models against the force of gravity - model aircraft don't have that advantage.

Regards, Greg.P.

They do, but scaling power and weight IAW the weights and measure of the prototype can be difficult. In 1959, Canada scrapped its only supersonic plane. In the mid 90's, CBC produced a movie about the plane which included some footage of the real plane and its 1/10 scale model which represented the flying prototype. You can tell discern the model from the actual plane because of its movements. On a sidenote, the modellers discovered that the more power they put to it, the faster it wanted to go. This was similar to the prototype as its limiting factor was skin temperature. But, they never got the chance to find out.

If gearing and weights on HO were accurate, then 5 mph through a yard could be realistically modelled. But, who wants to wait that long?

Cheers, John

"John Fraser" wrote

Me.

And, I'm given to understand, a rather large number of others as well.

-Pete

The model train problem is more one of friction than mass. Our bearings have proportionately more stiction and friction than the real ones. In particular, overcoming stiction is far greater than for the prototype, so our trains leap from zero to an unrealistic speed very quickly. If you add momentum effect to your controller then scale speeds mixed with foreshortened tracks is quite taxing to operate.

Greg.P.

Sorry, but I'm not buying the "large" numbers of others. There's just too many "roundy-rounders" vs. those who merely operate their trains, let alone those that would move at 100% realistic speeds at all times. Let me put it this way: at my 60+ member club, I think there's maybe 1 or 2 guys that I have seen try to operate realistically while switching. The rest stop too abruptly (sometimes for magnets), accelerate too quickly, or couple up to a cut of cars that should be 10x the weight of the switcher and yet there is hardly a pause as all the cars instantly accelerate to the switcher's speed (one of these days, someone will invent -BEMF for decoders). It's not like they are zooming around the a layout at 200mph, but they are taking "shortcuts" to realism.

Paul A. Cutler III

************* Weather Or No Go New Haven *************

Since an HO model has 1/87^3 the volume of a full-size car, its mass should be in the same proportion. That makes a 200,000lb loaded car about 4.9oz in HO, and an MT of 100,000lb about 2.5oz. The NMRA recommended weight for 40ft car is 3.8oz. The NMRA recommended weight depends on car length, not prototype weight, and was arrived at after lengthy testing (in the 1950s IIRC.) It may be time to update the RP in light of better trucks, but it still won't change the fact that momentum does not scale at all well, neither does rolling friction, both of which determine how far the car will roll without braking. A full size car travelling at 5mph might roll 100yards or more on the level - there is no way other than a motor inside th car to mimic this behaviour in an HO model.

If you think that scaling the mass to 1/87th in hopes of getting corresponding momentum, well, 1/87th of 200,000 lbs is 2,299lbs... ;-)

HTH

ph through a yard

s. =EF=BF=BDThere's just

Do the old John Allen " ball bearings and buzzer" in a box car idea and have the club vote to approve a .25 or $1.00 fine for anytime an operator buzzes the buzzer during an operating session. It's a great way to pay for the Christmas party AND make operators learn to operate more correctly.

momentum

I lived in Roseville, CA for several years, and enjoyed watching flat- switching in Roseville yard. The cars would coast majestically forever, even at almost imperceptible speeds, the empties coupling with huge echoing crashes. This fascinating action all seemed to happen in super-slow motion.

With absolutely frictionless bearings and cars cast from depleted uranium we might be able to replicate that, at least in F-scale.

I seem to recall an article in RMC or MR some 40 years ago that involved a rubber band around an axle drum, passing through a hole in the boxcar floor to turn the axle of a substantial brass freewheel. A few of those in the cut, and jackrabbit starts and stops might be reduced.

You know what?

On Thu, 1 May 2008 09:16:13 -0700 (PDT), I said, "Pick a card, any card" and the OTHER Mike instead replied:

This reminds me of the Top Post/Bottom Post argument. It drains the fun from any discussion when the train police show up.

-- Ray

"Ray Haddad" wrote

Sure, but you learn to expect that attitude from some people. I see the same exact situation in the music profession almost every week: "Drummers aren't

*really* musicians.", "You can't play the Blues on a banjo!", yadda-yadda-yadda...........and in most cases the best thing to do is just smile, say something non-committal, and go your own way.

But when there are a majority of them in charge at your club or whatever, and they begin leveling fines on anyone who doesn't operate the way they think you should, it's time to politely leave and either form your own club or build that railroad you've been planning all these years.

-Pete

This comes back to the dream which i have had for a long time for DCC - I want to see a throttle with the control features of the old TAT-IV throttle. IOW, not just basic acceleration and deceleration momentum effects, but both a throttle and a brake handle, with release, service, lap, quick service and emergency positions on the brake. You can shut off the throttle but your train would continue to coast, only decreasing in speed very slowly like the prototype until brakes are applied. Like in TrainSim. Let's get some realism in trying to bring your train to a stop at the right spot, with over or undershooting the station or siding.

Ya mena, like "What's the difference betweena drummer and a large pizza? THe pizza can feed a family of four."

or

"A gentleman is someone who knows how to play the banjo - and doesn't."

bada bing

This may get someone "Off the Dime" so to speak. Because doing this would a fairly 'trivial' thing 'electronically speaking'.

Chuck D.

"Steve Caple" wrote

Nope, but you score extra points for knowing a couple of generic musician jokes.

What I'm speaking of are the guys who really and truly think that Ged appointed them personally to police the way other guys run their trains, play music, or any other occupation you can name. And who are more than willing to get in your face and tell you all about it.

For instance: I recall an occasion on this newsgroup a few months ago when I posted asking if anyone knew where some old Walthers folded-paper passenger-car diaphragms could still be found, and one sanctimonious soul began his reply with "REAL modelers use such-and-such diaphragms"...

...There's a wonderful old-time musician named Doc Watson who was once being interviewed by a somewhat arrogant young writer, who began her interview by asking, "Doc, you don't really play Bluegrass or Blues music, so what do you call the stuff you play?"

And Doc, who was quietly simmering at that point, replied "I don't know what you call it. But it's my guitar, and I play whatever the hell I want to play on it".

Good for Doc.

-Pete

[...]

The really dangerous ones are the folk who decide that they have the Truth about politics and religion. 'Cuz G-O-D told them so.