Re: weights without rubber?
Tim,
As you may know, there are three different plans out there for the Rat. At least in the club I fly with, no one really mentions which plan you're supposed to use, just that it has to be per plan. So mine is built to the plan that says zip about wire sizes.
That said, considering that the model remained usable as it gained probably two grams in glue and balancing weight to counteract this and that, the motorstick need not be terribly strong. Mine was not from high grade wood. A decently selected 4 lb motorstick is plenty (it's thicker than my pennyplane motorsticks and uses less rubber). If anything, you want a little bowing so that the model will run flat for a few seconds and gain 4-5 ft of altitude before pitching up and mushing about for then next minute.
Good flying,
Joshua Finn
--- In Indoor_Construction_at_yahoogroups.com, "timjohnston878" <timjohnston878@...> wrote:
>
> Joshua,
> could you please expand a bit on how you achieved a weight of "around 4 grams" for a hangar rat? My understanding is that if they are built to plan there is in excess of 1 gram just in the wire parts.
> Did you use 32 thou wire?. Also most 4lb wood would not cut it as a motor stick I would think. Have you got an idea of the weights of individual components? and was is according to plan?
> Best regards
>
> Tim
>
> --- In Indoor_Construction_at_yahoogroups.com, joshuawfinn@ wrote:
> >
> > Tim,
> >
> > I finally tossed it because it just plain wore out (meaning it was mostly glue), but I had a Hangar Rat which would do 3:30 in Cat I. You have to work hard to get this level of performance from them. I was flying on a loop of .075-.080, 36" strand before tying. The model was somewhere around 4 g finished, and this was achieved by using 3 lb wood in the tail, 4 lb elsewhere. Even after gaining a full gram of weight it would still do 3:20 or so, which was enough to win consistently in local HR mass launches. Flight profile was to run in tight right hand circles by using plenty of right thrust and right rudder with left wing washout. You need the CG to be around 40% chord to do this. Launch was a fairly quick leap into the air with the model pitching to 30 deg nose up after reaching 5 ft altitude, where it would stay for about 30 seconds before slowly climbing away to about 20'. Around 2 minutes it would level out and slowly come back down in circles widening to about 25' diameter. This flight trim setup takes a while to achieve, but operates on loading the prop down as much as possible to limit climb while slowing the RPM's until later in the flight.
> >
> > This trim setup also works to a lesser degree on FAC Phantom Flashes, which will do 2:30 in Cat I if tweaked just right.
> >
> > Another fun model is the old Comet nickel ROG, which takes 30 minutes to build and will do about 2 minutes in a Cat I site. Unfurtunately, you do need pretty thin rubber to make it go.
> >
> > Good flying,
> > Joshua Finn
> >
> > --- In Indoor_Construction_at_yahoogroups.com, "timjohnston878" <timjohnston878@> wrote:
> > >
> > > Hi all,
> > >
> > > I'm new here, and am keen to learn from the many experienced builders that kindly share their knowledge. I have been building some indoor planes along the lines of penny planes, and smaller to fly in my living room, and I think I am getting better at building light.
> > > Seems like a lot of it is selecting the most suitable wood for the job! ( and practice !! )
> > > I have recently built my second Hangar Rat, and have a question about the expected weight. Is it usually quoted as without the rubber?
> > > The plane complete is 6.4 grams, and the rcommended rubber weighs an additional 2.5 grams. I have not seen any mention of the expected weight of hangar rats, so I don't know what to expect. I did put a bit of effort into selecting the best wood for this plane, but have not been able to find any weight anywhere? Anyone got some experience with Hangar Rats? I know they are pretty crude compared to the creations that you guys can come up with, but I am hoping that I can have a plane that will be somewhat competitive in a fly off at an indoor meet.
> > >
> > > Thanks for any assistance.
> > >
> > > Tim
> > >
> >
>
Received on Sun Apr 07 2013 - 05:09:26 CEST
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:47 CET