A member of our club just purchased this airplane and did not know the name of it. It really looks great and I wanted to see if anyone could help identify this airplane and share any information about this model.

It has an older O.S. Max-H 80 engine (late 60's early 70's) that started up just fine with new glow plugs. The fuselage is all fiberglass and the wing appears to be a foam core with sheeted balsa.

Thanks in advance.

Jim

It gives me a little Quick Fli MK III feeling.

Anybody notice the 4 digit AMA number and the slots near the wing tips? Very nice looking model though.

FB

Beautiful looking airplane!

Enjoy it.

It looks like a marriage of a Quick Fly III and a Sr. Skylark. No clue.

I can't identify it either. Someone already mentioned the wing slots. The wing tips are not very 'Quick Fli'-ish. They seem to flare outwards at the trailing edge. Kinda matches the stab shape. Pretty plane though.

Jim, is the airfoil symmetrical?

Tom

Could it be an Andy Lennon design? He uses slots and flaps and all kinds of high-lift devices in many of his designs. Most of his plans are available through M.A.N.

I would be surprised if the slots are combined with a fully symmetrical airfoil.

Kris

Did anyone notice the OS .80 dual-plug engine? A rear intake engine that wasn't very powerful, even for its day. I think they also made a .60 in the same format.


Ed Cregger

I had one of the 80s years ago but never could find any use for it and sold it.

Looks like this one has everyone stumped!!! I've never seen anything like it.

-----------------


I saw a few models fitted with this engine back in 69 or so, and the engines had a few years on them then. Everyone bowed in reverence, because it was one of the largest glow engines made at the time. Getting props for them could be tough. Not many hobbyshops stocked them.

In the very late Sixties and early Seventies, occasionally someone that was particularly enamored with a certain design would go nuts and reproduce them in plastic (Europe) or fiberglass and foam (USA). Some would change the model just a taste so that they could avoid paying royalties on particular kit designs (swept rudder hinge line). This appears to be one of those models. It looks a lot like a pseudo Kwik-Fli.

Back in those days, when most R/C pilots learned to fly, they used basically free flight models with R/C interuption (Sterling Mambo series, Midwest Squire). Pattern models, specifically the Kwik-Fli series, gained a reputation for snap-rolling on takeoff and landing. Today they are considered just average models, but our pilots have different expectations today (simulators DO help a lot). Remember that in those days, a new four-channel radio could easily cost a month's salary, hence the cautious attitude and the preservation and common use of stable aircraft. I suspect that this is the reason that this model's wing is equipped with slots, to tame down the snappy nature of such a model. Of course, the addition of such slots probably killed the model's pattern flying ability.


Ed Cregger

So the slots spoiling the airflow, would help keep the plane from tip stalling?

Not quite - see [link]http://en.wikipedia.org/wiki/Leading_edge_slot[/link]

Ray

"A leading edge slot is a fixed (non-moving) opening behind the wing’s leading edge. The slot does not operate at low angles of attack, like those found in cruise flight. At low angles of attack the airflow just passes over and under the slot.

At progressively higher angles of attack air starts to move through the slot from the higher pressure air below the wing to the lower pressure air on top of the wing. The mixture of the air coming over the leading edge and through the slot has greater momentum and thus sticks to the upper surface of the wing to a higher angle of attack than if the slot were not there"


Makes more sense to me now!
Afterthought, Why would you want them on a pattern plane if it will affect the higher speed performance though?

You wouldn't, especially not on a thick, constant chord wing as used on the mystery model. This is the first pattern design I've seen with them although someone will probably prove me wrong!

Ray

Hey Ray! Would you have a copy of RCM September 1993? TIA!

FB

BTW .... Your Troublemaker package should go out this weekend.

FB - sorry ain't got that one - 1993 is way too up to date for me. Decent magazines, like decent music, stopped about 1970!!

Great news about the Troublemaker. The Rhoms are working and the Enya 61 is run in so i'm keen to make a start. Haven't seen much on the Banshee recently - how's progress.

Ray

I guess that makes Britney Spears the 'Backyard Flyer' of the music world. I know what you mean Ray. I'm sort of rediscovering classic music as well as classic planes.

Tom

You mis-read that description you posted. The slots do not come in to play at lower angles of attack (usually equated to a higher airspeed, but not necessarily). Having the slots on the tips allows the stall speed on the wingtips to be lower than the wing root, reducing the liklihood of a tip stall on takeoff or landing.

Sorry to be pedantic but I would rephrase that as " the stall angle at the tip to be greater than the root"

Airfoils have a stall angle not a stall speed.

Ray

---------------


Yes, they could make autorotation upon demand nearly impossible with any level of predictability.


Ed Cregger