Marcos Nieto

Hi guys..............Finally I´m ready to test fly tomorrow my Funtana90/OS 120 combo. The final RTF weight is 9lb 12oz with a 2000 mAH 6Volt sub C Hydrimax batt. pack. Every thing else standard. From what I have read in this forum, this plane is in the heavy end. What is your opinion on this issue and if possible please give me some feedbacks on weight/performance experience.

Thanks

Marcos

Razor-RCU

My Feedback: (50)

Marcos- Good to hear you are RTF! I have been researching this airframe and it seems the goal is to be near 9LBS AUW/dry. Most folks using the Saito-100 have been near 9 or below - That does not mean yours will not fly well but it does seem to be on the heavy side---

How much does that RX batt. weigh? Also, how much does the 120 weigh?

Mine will be with an OS-160, ST-2300, or Saito-150 so I am sure I will be heavy also---

Let us know how it goes!

P.S. What servos are you running?

codiddley

My Feedback: (4)

Mine is in the same weight class- plus a few extra OZ's for a 180. I also live at 5,280', and the field I fly at is about 6,000'- so yes mine few a little like a "heavy" but is still extremely nimble- I only got two flights before an engine failure forced me into the ground (engine leaned hovering about 30' off the deck).

I did however order a new set of gear from Fiber-Lite, and combined with titanium axles and light foam wheels I should lose about 4 oz's off the airframe weight. There are lots of way's to keep the airframe light- lighter fuel tanks, pushrods, wheels, props, spinners, the throttle servo, and other hardware. The cheapest way is with wheels, and maybe an OZ from a new tank. You shouldn't be dissapointed with it once it's airborne.

Good luck

Cody

3dbob37n

Golly, weight or no weight, this is absolutely the lightest model I have flown. Understand that I mean it flies light, like a feather. It is one of the most enjoyable experiences in a model.
I fly mine with a Saito 150 and put in a bigger fuel tank.
I don't know how one could get a model any lighter than the F-90 and still hold together.

enjoy

3dbob

chesie2

My Feedback: (55)

I have a funtana 90 with a YS 91 on it flies great !
I am looking for what prop to run??

STG

My Feedback: (26)

Mine is 10 pounds with the OS108. This plane comes in heavier than advertised, but is still very light. With 1100iches stable wing area and at 10 to 10.5 pounds it flies great...you just have to power it properly if you want unlimited performance. Think of it as a F120 and not a F90.

Ditch those Sub C batteries and get a nice 1800 mah 5 cell 6V pack the weighs 5oz.

http://www.cheapbatterypacks.com/main.asp?sid=327570

wind junkie

My Feedback: (1)

Don't worry so much about the weight. What size tank are you using? Did you ever weigh the plane with a full tank? Ask yourself if you can really notice the weight difference between a 9 lb plane and a 10 lb one, because that's what you have at the end of a flight vs the beginning. While it's certainly a good idea to save weight wherever you can (and can afford), a plane this size doesn't need a 5 oz saving on any single component.

I find a plane this size can carry the extra weight for the power you really want to use for 3D.

My prior experience was mostly 40 size 3D profiles, and I find the F90 (or F180 in my case) very easy to fly.

The E conversions I've been reading are much heavier than ours here, and nobody says they are too heavy.

3dbob37n

Hi guys- I think I have uncovered a major flaw in the Funtana series. The reason they added the wedge at the trailing edge of the wing at the root where it joins the fuselage is also discovered.
Our three Funtana 90's and a 40 all have the same problem. Pull up and they roll to the right, against the engine torque. Almost impossible to do a good Humpty Bump or a square loop.
BUT, we got it fgured out. On the bench, holding the Funtana, run your engine up to full power. Put your hand on the right side of the vertical fin. Now put your hand on the left side of the vertical fin. You will note that there is a lot of prop blast going over the right side of the vertical fin and none on the left side. VOILA! The prop blast is curling under the bottom of the fuselage (P factor I recall) and at a high angle of attack, it is sufficient twist to push the vertical fin over to the left, giving you a right twist during the pull up. And, that is why they added that wedge between the wing and fuselage, hoping to interrupt the airflow hitting the vertical fin. Unfortunately, it did not work but so far, the designer did not want to reveal the problem. As we know, prop blast tends to curl around the fuselage and in this case, hits the right side of the vertical fin. There is no obvious cure to the problem but at least the cause of the problem is known. We had earlier added a taped on dorsal fin ahead of the vertical fin but that had no effect. Seemingly just a freak situation on the Funtana's.

3dbob

Not24

My Feedback: (1)

I put a dorsal fin on mine, and I think it improved knife edge a little. Also, I would tend to agree with your theory, except for one tiny problem. The model will roll right during a hard pull, even without power. I think it may be a function of lateral balance moreso than anything. The bottom of the fudelage is flat, which is not very aerodynamic when you point it into the wind. There are many factors that cause this right wing drop,and the wing rock, we are all accustomed to. Did they put the fillets on there to help with this? Probably. What is really needed is to put those wings on a different fuselage, like an Edge or Extra, which have rounded undersides to see if the problems persist. Personally, I suspect the airfoil itself has its own set of quirks that cause the tip stalling. Also, sweepback angle plays a major role in roll coupling with rudder inputs. The sweepback has a positive dihedral effect the couples wildly with sideslip. The straight leading edge of the Edge would have zero roll coupling to yaw inputs. That is assuming you are just flying the wing and not the fuselage, because the fuse can induce roll moments itself, independent of wing planform.

EYB

3dbob37n

I have looked and looked and flown that quick pull up maneuver time after time and all I see is a rudder type input. There is no tip stall and this would be almost impossible with this type airfoil. Keep in mind that the airfoil starts at about 12% at the root and progresses to 14% at the tip which means the tip keeps flying well beyond the root.
I really don't agree that the bottom of the fuselage would have any impact as well. The airflow is simply rolling under the fuselage and swings down from the prop tip underneath and then up the right side.
if you don't believe me, do the same trick I used and you will find a heavy air flow on the right side of the vertical fin and none on the left side. By all rights, the flat bottom of the fuselage should smooth the air flow.
Anyway, try the vertical stabilizer thing I mentioned and see if you don't agree.
Would like to have more input on this.

3dbob

Not24

My Feedback: (1)

Could the reason for the flow being stronger on the right side of the vert be due to the massive amount of right engine thrust? I appreciate your interest in finding the fix for this problem, but P factor causes a left yawing tendency, as the spiralling slipstream pushes on the left side of the vertical. I have designed and flown several models of various planforms and layouts, and I also am a private pilot, so I have much experience with the effects of P factor in aircraft design. Unfortunately for me, I have all my gear in another plane right now and can't try the test you suggested. I certainly would if I could. As for the airfoil section, you are right in that it is not constant, but it varies much more than 12 to 14%. It is more like 12 to 24%, and this may still be the cause of the tip stall. I have flown another aircraft with this type of constant thickness tapering planform and it tip stalled very easy. It was just a little more pronounced than the Funtana's, but it also reacted much worse to hard pulls. Just because the airfoil is fatter, with more curvature, doesn't mean it stalls at a steeper angle. In other words, there are more variables to consider when determining the stall characteristics of a given airfoil than just the overall thickness. Look closely at the tip airfoil on your plane. The shape is not smooth at the point of the main spar. There is a break there that is not there at the root. Could this be the culprit? I wonder. Keep it coming.

EYB