The resonant frequency of the .015s will be higher than the .018s. Resonance is usually more of a problem when line size increases, so it's probably not a big deal. The .015s are stretchier than .018s, although you could use Staystrates, available from PAW or Eric Clutton. They are stiffer than seven-strand .015s. I haven't compared them to seven-strand .018s, but maybe I should, because I'm now entitled to use .015s. I'd try them and spend a few flights fiddling with trim before deciding which to use.
Under the new rules I can fly my 54 ounce ST 51 powered Skylark on 15's. Been flying it on 18's and thinking if I went to 15's I could add a foot and still reduce the line drag by 0.8 sq/inches and line weight by about 1/4 ounce.
Thought this might be an intresting topic for discussion, wouldn't think I'm the only one that has an airplane that falls into the range where 15's are now an option.
with the kind of furious whip-up you get with 4-2 motors or 4-strokes, no way.
I hear yah...
Gordy's Saito 72 powered Tony sucked that year.
Constantine's high pitch/low RPM 4-2 motor was horrible in the wind too. n~
Gordy didn't fly both flights that day. In Open, only seven guys did: three piped PA's, one piped RO-Jett, one piped OS .40 VF, Konstantin's, and whatever Dan Banjock was flying. Dan, of course was laughing throughout both his flights. The thing that impressed me about that group is that three of the top five built their own engines.
Gordy didn't fly both flights that day. In Open, only seven guys did: three piped PA's, one piped RO-Jett, one piped OS .40 VF, Konstantin's, and whatever Dan Banjock was flying. Dan, of course was laughing throughout both his flights. The thing that impressed me about that group is that three of the top five built their own engines.
Unless your airplane needs a lot of line force to deflect the controls, I'd guess you would prefer the .015s. I am not sure that the .015s are stretchier than .018s, because .018s have more of a curve because of drag. Does airplane weight affect the combined delta stretchiness? This is on my list of stuff to think about.
You can use whatever you want, though, and show us how. Alternatively, you can use actual facts to support your argument. But if you tell us that four-strokes dominated the 2003 Nats, somebody's going to call you on it.
All I did was address Brett's comments. Something to the effect that only pipes do not wind up... "I wouldn't trust .015s in those conditions even with a piped engine (the PA61 was 16-stroking and sounded like it had a potato in the exhaust at the bottoms of the loops, to the point I though the plug was going to cool and the whole thing quit), with the kind of furious whip-up you get with 4-2 motors or 4-strokes, no way" which is load of you know what, and he knows it.
Back to line stretch, has anybody calculated the effective stretch due to the lines bowing back from drag compared to the elastic stretch of the material? I kinda suspect that the .015s would compare more favorably for stretchiness to .018s for light airplanes. Relating this to the 2003 Nats, I wonder if the reason you crashed and I didn't was because I was using .015s.
OK, Brad, everyone is paying attention to you again! I hate to dignify yet another delusion-of-grandeur hissy fit with a sensible response, but hopefully everyone else will learn something even if you are incapable.
5.5 was a little pokey that day. I was screwing in the needle valve.
Now that I think of it, I'll bet Bob Reeves is chuckling at this four-stroke-in-the-wind discussion. He's been flying four-strokes in Tulsa for years, and, as I remember, Tulsa isn't exactly the Horse Latitudes.
It is kinda ironic that the engine that gave me the confidence to make the jump from being afraid to fly in anything over 10 MPH to competing in almost anything anyone else will fly in was a Saito 56 turning a 13-7. This was after a solid year trying to get a Stalker 61 working in all conditions without success.
That won't work, it will whip up ferociously... a guy on the Internet told me.
Yah, Brett, I am throwing the hissy fit...
Gordy didn't fly both flights that day. In Open, only seven guys did: three piped PA's, one piped RO-Jett, one piped OS .40 VF, Konstantin's, and whatever Dan Banjock was flying. Dan, of course was laughing throughout both his flights. The thing that impressed me about that group is that three of the top five built their own engines.
Got anything rational to say about speed stability for 4-strokes that might actually help someone?
My Shrikes are 50 oz planes PA 40 on pipe 63 ft lines 5.3/5.4 and they are about all i would be comfortable with on .015s,
Any thing larger or heavier are on .018s.
Busby
Now, if we add in something like line stretch or bowing of the lines or whatever muddies up
the control function, the flier is indeed able to feel it. Whatever minimizes such effects would
be desirable.
I'm still watching
Whoah! Your Shrike only weighed 50 ounces?
Watching what?
So no bickering continues. I am also interested in this tread as I plan to fly my PA.65, 53 oz Viper on 0.015 lines unless the wind becomes severe then I will switch to 0.018 lines as to why take a chance on loosing my plane.
I think the plane needs to be 54 oz or under to have any *advantage* on .015's.
So no bickering continues.
Yep BUZ's plane weigh 50 ounces...Curt's weighed 48 ounces...someone else had a 60 ouncer ::)
I'd like to see some calculation--just of the static stuff--to show why. I'm too lazy to do it myself. Maybe we can goad Brett into doing it. He knows how.
Two pros, neither of which will convince the other of righteousness of their viewpoints...
I was thinking about 90 degrees to the wind. Does it calculate the line shape there?
I was thinking about 90 degrees to the wind. Does it calculate the line shape there?
ie, plane directly downwind? or, as in the lines 90° to the wind (plane heading directly into the wind)
Wouldn't this become a vectors problem? All the program has to do is calculate the relative wind to the plane and lines at any point of the circle.
Not really, it basically assumes the wind cancels itself out for one complete lap. I can't remember how the wind parameter is used in the calculations and didn't play with it when I was writing the user interface.
I'd like to see some calculation--just of the static stuff--to show why. I'm too lazy to do it myself. Maybe we can goad Brett into doing it. He knows how.
I'd like to see some calculation--just of the static stuff--to show why. I'm too lazy to do it myself. Maybe we can goad Brett into doing it. He knows how.
Curt's weighed 48 ounces
Interesting, mind expanding on how resonance of the lines effects our stunt ships?Think of them in terms on guitar strings;if you,re a picker, and the thing begins to make sense.
Have read Brett and your comments on 15's being stretchier, could be interesting to try to find the magic point of line length and airplane weight where the reduced drag is offset by the lines being too much like rubber bands.
Think of them in terms on guitar strings;if you,re a picker, and the thing begins to make sense.
long scale necks Vs. short scale necks (tuned to same pitch). .009 string tuned to E pitch Vs..012 string tuned same.
try and push a .009 now a try and push a 012 enough to raise the the pitch to the same point as you did the .009.
If you can, you probably have the strength to break the handles off your pliers.light guage hard to keep in tune compared to heavy
Curt's plane was smaller and lighter, and the judges did not know it... kind of shoots down the idea that "you must fly a big plane to score" idea.
I would point out that Curt's airplane (and Phils, during the "small airplane revolution..." a few years ago) aren't really very small at all. They are right in range of most of the planes I see and fly. David's WC airplane is smaller than Curts or Phils. They are small compared to some of the 700 sq in models flown back East (and Paul's super-giant electrics) but larger than the grandaddy of our airplane designs, theImitation.
Brett
My Vectra, from 1987, used a 40 but had a 51 and 61 in it, it was 647 sq in, but seemed to perform as well with a hi powered 40 as the larger cube motors. I gleemed from that test maybe matching the power plant to the plane , could give as well if not better results than stuffing in all you could. This works for some designs but is not conclusive on other. I know my KATANA perform no better or worse with a 65 in it rather than the stock 51 it has ran .
It was interesting about 15 years ago Brian Eather asked for plans to my Vectra Dreadnought. after getting them his comment was "why so tiny".