Thanks for the details. It will be interesting to see, how the models
will evolve for lower ceilings, where VP is needed... I guess winding
the motor to the max would still be needed, but would the climb trim be
less crucial then?
> Both Cornel and Zoltan's model used a spacer of 200 mg, so for the
> airframe, they are flying the old rules models. Zoltan moved his rear
> hook from 1-2" behind the wing to just in front of the rear wing post.
> ... Cornel's rear hook position remained in the same place as his old
> rules model.
Did they use a ballasted spacer or was it just to relieve the motor?
What I'm aiming for is did they move the center of gravity of the models
more forward, or was it the same as with old setup?
>
> Their models have very fast climbs to 160 to 165'. ... Once to the
> top, the models have very efficient cruise and descent. The
> combination of an aggressive climb and efficient cruise/descent is
> what most people struggled with. For models that don't have the right
> combination, when trimmed for a good climb, the trim would be under
> elevated in cruise and descent. ...
I think this was the case already with the old rules. You need to trim
the model for cruise, and then work the trims so that the initial climb
is efficient. Interesting point that shortening the motor tube would
reduce the impact of stick bow.
>
> Zoltan used a new small 16.5" diameter p! rop. Cornel's was ~18.3" and
> shortened from his old rules prop of ~18.9". Last year, Brett and I
> used 18.3" props. Cornel's average RPM was about 46 and Zoltan's about
> 55. It is likely that a smaller prop with thinner rubber, climbing at
> lower torque, makes the climb easier to trim. But is the smaller prop
> more efficient in the climb than the larger prop? I don't know. If
> it's true, it's not for reasons obvious to me. Is the smaller prop
> more efficient in cruise and descent? I don't think so, but I also
> don't really know.
>
The prop theory says that the larger the prop, the more efficient it is.
However I think that a smaller prop makes trimming the model easier. If
I may make a crude comparison to outdoor FF models, I find that my P-30
with 250mm prop is much more forgiving to launch than my F1B. For the
latter, a bad launch easily leads the model hanging on the prop until
the prop stalls, whereas in P-30 the smaller prop with higher rpm goes
on unstalled and can pull the model through improper position and
gradually lower the nose, thus getting through without losing much
altitude. Parallerly I'd assume that a smaller would stall later, and
also give less torque, so it would make it easier to manage the initial
climb phase.
From the RPM:s I count that the guys must have winded 1300 to 1500
turns to their motors.
-Tapio-
>
>
>
>
> ---In Indoor_Construction_at_yahoogroups.com, <tapio.linkosalo_at_...> wrote :
>
> Most people seem to be pushing in the 20 to 23 minutes range,
> yourself included. I recall you mentioned before that you fly with
> your old rules models, using 2/3 motor and 1/3 ballast, is this
> what others are using too? It seems that Zoltan and Cornel and
> Popa have cracked the new rules, discovering something to adapt
> their models to the new rules? What is that? In previous message
> Karol mentioned that people are desperate for smaller props, so is
> that together with thinner motor the answer for longer flights?
>
> I am impatiently expecting a report / an analysis of the models of
> the winners!
>
>
>
>
> -Tapio-
>
>
Received on Thu Apr 02 2015 - 22:42:31 CEST
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:48 CET