Groovy 90 3A
 

Planning on getting a practice pattern plane in 90-110 size. Right now I'm planning on getting a Groovy 90 since its available in our LHS. Anybody experience this particular plane? For the price of $259 it comes with wing and stab adjusters, engine mount, carbon landing gear plus the usual stuff of an ARF.

RE: Groovy 90 3A
 

HI pmr

You can read here and learn more about the groovy.


http://www.rcuniverse.com/forum/m_31...tm.htm#3182791


Good luck

Ram Zahavi

RE: Groovy 90 3A
 

thanks ram z.

RE: Groovy 90 3A
 

I have a question...How do I adjust the angle on the stab with the wing? How do I know what angle to use?

RE: Groovy 90 3A
 

That's a big subject with a lot of interactions involved----
But basically, all modern pattern designs have a symmetrical wing section, so the wing needs to be at a slight positive angle relative to the tailplane,to provide lift to defy gravity when the model is flying level and upright.
Sooo----set the model up on the bench so that it looks "right" in the side view, i.e. how you'd have it looking flying level.
Then set the tail,with the elevator absolutely neutral, at 0 degrees with your incidence meter.
Then set the wing at 0.25 to 0.75 degrees positive relative to the tail(Wing T/E lower thanWing L/E)
Use the lower figure if your model is at the light end of its possible weight range, and go higher if it's at the heavy end.
There's a lot more, re. C.of G., trimming for straight down lines, etc., but hope that's answered your question!

RE: Groovy 90 3A
 

Yes, thanks very much, I will do as you say. I always thought that I should set the wing and stab at 0 degrees, without the slight positive angle. Is this not correct for a pattern plane?

RE: Groovy 90 3A
 

It all depands on how you would like the plane to fly. I have always set all of my planes to 0-0 to start with, I like them to be fairly neutral both upright and inverted, with very little down elevator input. However, other pilots like to fly with more down ele while inverted.

According to a few of my friends with the Groovy, they are a bit on the tail heavy side to start with, all of them ended up adding weight on the nose.

Adrian

RE: Groovy 90 3A
 

I called Fai at Airborne Models when I ran into the same problem building mine. The trick with the Groovy 90 is to use the built-in down-thrust angle of 2 degrees as your reference for setting the stab: Block up the fuse so it doesn't move on the bench and put your incidence meter on the thrust washer (motor is installed). Now, you can either set it to "0" or "-2" degrees, whatever you like. If you set it to -2 (that's what I did) when you move to the tail, set your incidence to 0. Next, set your wings at +.5 for starters. This will get you in the ballpark. If you start with a reading of "0" on the thrust washer, make sure you think it through as you set everything. You'll need to use +2 for the stab. and +2.5 for the wings. Make sure the meter is facing the same direction for all of these operations or your readings will be wrong (ask me how I know this).
Mine was tail heavy with an OS 91Fx. I guess a carbon stab. tube would help. One other thing - the rod that is used to hold the stab incidence was a loose fit in the little brass tube on my model. I think it's 3mm (can't remember). I used a piece of 1/8" music wire instead - nice tight fit.
This plane is good for Sportsman and even Intermediate, but try to keep the weight down. Mine came in at about 9 lbs. With a 91 (w/o pipe) it's marginal for Intermediate.

John Pavlick
http://www.idseng.com