Rffs-100 Ifo

[pease1]

I'm thinking of making my first RFFS-100 plane be an ultra slow flying IFO. I'm figuring the CF frame will take the punishment of flying indoors, and the IFO design is maximum wing area for minimum of materials (weight)

I'm thinking about 1mm CF rod for the frame, and 1/32" balsa for the elevons. I'll aerodynamicly balance the elevons, although I'm not expecting IFO like acrobatics from the DU KP-00 setup.

Here's my question: what size IFO do you all suggest? I was thinking like 60% of the mini-IFO. I'm also planning on leaving off the wheel, opting for just a skid to protect the prop.

Support? Ideas? Laughing? tell me!

[Fwilly]

go down a few threads to the "micro ifo" thread it has some discussion about using actuators on an ifo towards the bottom of the page
you might want to try the other kp00 ratio it has a gear with the teeth on the inside and is suposed to swing a 5" prop. this might give you more ifo like aerobatics. good luck

[KeithK]

Pease,

I thought of the same thing. I have had several different sized IFO's and like the way they fly. The problem I see is that they have to have a bit of reflex. I thought of a typical carbon half circle front and 1/32 balsa elevons, but not sure if the actuators should have power to them at all times to hold the "up" (reflex) or if some up should be built into the balsa pieces holding the elevons (piece between the CF and the moving elevon). I was planning on a 14" IFO and about 1 ounce. After playing with my converted hangar rat, I decided to wait on this till I can get a better gear system to swing a bigger very low pitch prop. All my IFO's have a tendency to tuck when flown fast and the actuators may have a hard time overcoming this trait without a big prop to help them slow down. Will be interesting to see the first aerobatic plane with actuators.

Keith

[Fwilly]

Now you've got micro ifos stuck in my head again and now I want to try one. I was thinking of using push rods and putting longer control horns on the surfaces and short ones on the actuators to get more tourque. how much control surface deflection (in degrees) do you need for an ifo to be fun to fly?

[Dave Robelen]

Hi Guys,
My first machine with the RFFS-100 was a 13.5" span delta that weighs 25 grams with 3 cells. There are a couple of ways to get the reflex. The first is to use a strip of balsa to mount the coils and set the reflex in that. The control can then be streamlined with the mount. It is also possible to offset the magnets in the coils so that the system neutral will hold the elevons in a reflexed position.
For IFO type flying, I would sure vote for the higher gear ratio. The low ratio driving an U-80 prop was great on my clean little delta, but the low speed thrust dropped off pretty quickly. I am very pleased with a drive I assembled using 1 mm ID ball bearings from Dave Lewis supporting a 1mm propshaft and the 4.2-1 gears from Cloud 9. This drives a respectable size prop and is very smooth.
Cheers, Dave Robelen

[pease1]

I'll post a page with pics when I get to work tomorrow. Here's the skinny:

I got the micro-IFO to fly - controlled flight with the RFFS-100. My plane had a span of 22", and a chord of 10", total area estimated at 190 square inches. All up weight with 4-cell 120 mah NiMh pack was 39g. I had to go with the 4 cell pack for 2 reasons. First was to get the plane to balance, second was to get enough power in the actuators to move the somewhat large elevons sufficently to control the model.

I put a tiny bit of reflex in the elevons by mounting them up a half degree. The rest the actuators hold fine with trim. Balanced correctly the model really doesn't need any trim.

The plane flys well from 1/3 to 2/3 throttle. It's completely controllable but not what I would call nimble considering it's size and wing loading. It would fly in 1/2 a basketball court fine
though. Figure eights even. Above 2/3 throttle I get control surface flutter as the actuators fight the air. I did aerodynamicly balance the control surfaces, but probably should have gone for more forward surface. I may cut down the rear of the elevons a bit to help that.

All in all I'm sure this isn't the best use for the RFFS-100, but it proved my theory that it would work and was an easy build taking only about 4 hours total time to build. I'll fly it this way for a while, maybe order another set of actuators and another KP-00 to put in something more reasonable maybe a tiny sopwith pup!

[pease1]

OK, here's the skinny!

http://pease1.sr.unh.edu/aew/rc/DU-IFO/tiny-ifo.jpg

More photos and info as always are on my Micro-IFO Page (http://pease1.sr.unh.edu/aew/rc/DU-IFO/)

[pease1]

Film at 11 - or whenever you decide to download them.

I have posted 3 videos of my RFFS-100 IFO flying outside in near dead calm conditions.

They're on my Micro IFO website: http://pease1.sr.unh.edu/aew/rc/DU-IFO or you can download each individually here:

http://pease1.sr.unh.edu/aew/rc/DU-IFO/DSCN1709.MOV - ~6MB
http://pease1.sr.unh.edu/aew/rc/DU-IFO/DSCN1710.MOV - ~6MB
http://pease1.sr.unh.edu/aew/rc/DU-IFO/DSCN1711.MOV - ~4MB

Enjoy!
Al