Estes Falcon

You need an angle of incidence between the horizontal stabilizer and the wing AND the horizontal cannot be buried in the turbulence that comes off the wing.

It has to be able to pull out of a dive. The horizontal at an angle to the wing will provide lots of deflecting force to help pull the nose up when the glider starts out pointing downward.

-Fred Shecter NAR 20117

You need some difference between the angles of attack between the stab and the wing to get this bird to glide.

I originally took to putting a small wedge under the trailing edge of the stab to force this angle into place. If this wasn't done JUST precisely right, the bird would glide great, but loop into the ground under power.

The secret to getting good Estes Falcon performance is to put the incidence in the WING. (I stole this idea shamelessly from Kevin Stumpe, husband of NAR HQ manager Marie Stumpe.) He suggested 2-3 degrees of incidence in the wing to me during one of my NAR HQ visits. Putting the incidence there means it's close to the boost CG, and will thus have less of a moment arm to work through during boost.

As soon as the engine spits, then the CG shifts, and the moment arm gets a lot longer, and more effective. Instant pull-out from a dive.

How to get that angle in there, you ask?

You could try eyeballing it, but I prefer to cut a couple of small balsa triangles to the 2 degree angle, glue them first to the fuselage, then glue the wings in place using the triangles as a guide.

When I used this trick on my Canon City NARAM Falcon, it worked perfectly for 6th place in teams. Not bad for a 30+ year old design whacked together in less than 2 days. . .

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Mark B. Bundick mbundick - at - earthlink - dot - net NAR President www - dot - nar - dot - org

"A closed mouth gathers no foot."

Of course, the Falcon is really poor structurally in this area. Gluing the wigns to opposite sides of the keel makes it both weak, and difficult to align!

I never had the guts to try 3 degrees, but a little bit sure helps. It will work at 0-0 just because of vertical CP-CG misalignment, but it takes a while if it get's nose-down. The neat thing about a 1/2A6-2 is that the ejection charge has more impulse than the propellant. That's where I got the idea for the "cannon dart" B Altitude model.

At my first organized launch in 20 years (~98 or so), I took to Falcons to the LUNAR launch. Worked like a charm, of course, but I was truly a celebrity for a while, because very few of the people there had ever seen any BG work correctly. I was truly hurt when the LSO called my first launch a "heads up"!

Brett

Fred,

Thanks. I pulled out the sad remains, and yep, looks like 0/0 incidence between the wing and stab. I've already started cutting parts for the second one.

John

I was concerned about the wing butt-glued to the keel, but the joint did not break, the wings are in pieces. All that nice airfoiling, gone. I have started cutting new pieces for the second one. Thanks Mark and Brett. I give it some wing incidence and see what happens.

John

first launch a "heads up"!

With some of the unconventional looking stuff I fly (scratch scale air-to-air, & air-to-ground misslies with varying amounts of forward fin area, odd-roc, & unseen Shrox prototype stuff), I often get a heads-up call, or "everyone on their feet" from the man on the mic. I used to be hurt when they'd do that, but I realized they're just playing it safe...alerting the crowd to something with the potential for an unpredictable flight path. Afterwards, it's fun to watch 'em scratch their heads & comment on their surprise about what a stable flight it was......usually. -- Richard "they put me on the B-rack for my scratch Bell X-1 on an E15 & it flew very well.....I don't what went wrong 2 months later...bad motor, too windy..?" Hickok

Well, maybe I was exaggerating, just slightly...

Brett

Please describe this one. Sounds intriguing.

Scott McCrate NAR 71680

I've also done this by putting a standard glider wing airfoil on the wing, and an UPSIDE DOWN glider airfoil on the stab, producing stab downforce that way. But I haven't used this for MANY years...

The rest of Bunnys tip is being stolen for the RMR Glider FAQ.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Bunny's upgraded Falcon plans can be found in NARTS publication NIRA1, a collection of glider plans from our newsletter.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Speaking of 30 year old BG's and death-dives-

Of course, the Falcon was a ripoff of/inspired by/heavily influenced by the Sky Slash II. Pretty much the same thing, with the tip plates left off the wing, and a T-beam fuse. Even had the same structural oddity of gluing the wings directly to the fuse sides (and was even harder to align). But I wondered why it was the "Sky Slash II" vice "Sky Slash" or "Sky Slash I". I asked Larry Renger about it at a model airplane contest a few years back, and it turns out that Sky Slash I was pretty much the same design, but with a trigger to pop up an elevator, neatly solving the death dive problem. Problem was that on the very first flight it thermalled away! So he flew the other, non-pop-elevator model, the Sky Slash II - it didn't transition as well, but it also didn't thermal out on the first flight, so that's the one that got published.

Even with the less-than-ideal transition charactersitics, it was still on a different planet, performance-wise, from rear-engined models like the Space Plane and the like, so the rest, as they say, is history.

Brett

I remember talking with Larry about the same thing. The SSII was heavily edited by Estes from his original submission, because it didn't look enough like a rocket or even jet fighter. What he submitted looked much more like a conventional HLG of the 60s than the SSII. Don't remember getting into pop up elevators.

It took BG evolution several years to get back to where Larry started :-(

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Bob Kaplow wrote: The SSII was heavily

He mentioned that to me, too.

He's a pretty neat guy - a little eccentric (really into some strange corners of C/L stunt), but aren't we all...

Brett

The SAI Hawk is also a ripoff of the Falcon...

Thanks for that historical anecdote.

Alan

Indeed. Proving once again, the essence of good engineering is knowing where to steal good ideas!

Brett

plans?

Less lever, yes. Less force, no. How to practically "tweak" if you put in too much positive wing incidence? Reglue the wing or add down elevator...ouch. I'd stick to tweaking the stab.

Kooch

One other Falcon tip I thought of today.

Introduce some roll on boost.

I do this by canting the pod a bit to one side.

DON'T overdo it.

To get the alignment right, I center a 1/8" dowel in an expended engine casing, insert that into the body tube, and then align the tube on the pylon such that the thrust line is about 1" to the right of center at the trailing edge of the stab. If you more than 1", the model expends too much energy spinning and won't get any altitude.

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Mark B. Bundick mbundick - at - earthlink - dot - net NAR President www - dot - nar - dot - org

"A closed mouth gathers no foot."

Too touchy for my taste, Kooch. I tried that on some of the models, and couldn't get consistent results. Some worked great, while others did the loopy thing into the turf. And it's honestly not that hard to get nearly perfect alignment of the wings.

You just need a rectangle of 1/16" balsa as long as the root edge of the wing.

Now split the rectangle into two triangles, by measuring a 2-3 degree angle and cutting it on that diagonal.

Build the Falcon fuselague stock.

Now take the triangle, and glue the straight edge of one of your triangles such that the 2-3 deg. angle is located at the wing glue location.

Glue wings in place, and voila!

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Mark B. Bundick mbundick - at - earthlink - dot - net NAR President www - dot - nar - dot - org

"A closed mouth gathers no foot."