I have two sets of ribs and fuse formers for a 23” span Skylark and want to install a baby Bee .049 in it.  I thought I could double the formers and use thicker strip stock for the fuse than the plan called for, then extend the wingspan 50% using the extra ribs, but spacing them closer.

I purchased true LE/TE balsa that will widen the chord at least 1/2 inch and will modify the fuse wing mount (high wing aircraft) to accommodate.

I simply do not know if there is an algorithm for how much you can extend a wing span without scaling up the chord 1:1.  In my mind it will simply make more like a glider with long, thin wings, but still retain a conventional aircraft look.  In reality though, am I asking for trouble?

Thoughts?

YJ,

I don't know what your 1/2A Skylark looks like. That would help. It would also help to understand your performance expectations for the plane. Scale(ish)? Loops? Wingovers? Fly only in the dead calm, or in light breezes? Or full stunter?

I can say that a Baby Bee only has a given amount of power. Since these engines are often not stock and came in different vintages you will want to know if it is a single bypass or dual bypass engine. There's a noticeable power difference. And, has it been swapped around for other performance parts? High compression head? Larger venturi?

In full-scale aircraft design, the engineers use power loading as a metric. Same ideas apply here.

Upsizing the span by 150% makes it 34.5 inches.  If you only want to fly level, upright, and in calm wind this gives you your floaty glider. I have a design I call the Spring Break Special with 32" span and uses a Cox Medallion. With the Bee, I would keep it (well) under 30" unless you are after the floaty thing.

You are increasing the drag with the larger wing and you need to have enough power to get it up to the speed you want to fly. You can offset the power requirement somewhat by using shorter lines. There is more drag from the lines than the plane itself if the plane is reasonably streamlined. So with limited power, you can shorten the lines to reduce drag. And by all means, use either some light Spectra or .008" stranded steel to keep the drag down. The steel lines require careful handling to avoid damage.

Another way to bound your sizing question is to look at the weight. For a Cox engine, I wouldn't want the plane to weigh more than maybe 12 oz. So you can't simply keep growing the size without the weight going up or making a (more) fragile plane. The weight plays back into the power issue: the wing has to lift it, and the increased weight causes increased induced drag. If you are using a fat symmetrical airfoil then you already have a good amount of form drag from the wing.

As an example, a Baby Clown with a wingspan of 25-1/4" and chord of 5-9/16" (140 square inches) flies really nice with a dual-port reed engine. I haven't tried a single port engine, but it would likely do pretty well.

At the other extreme, consider the Baby Pathfinder. An excellent plane, by all accounts. A 35" wingspan and 236 sq. inches of area. But you are going to need a strong Medallion, a Tee Dee, or one of the .061 "half-A" engines. For a Baby Bee on a stunt capable plane you should be looking for something smaller.

I hope this helps you plan out your project a bit,

Dave

That, and the fact that I too am just learning stunt flying means I need a really stable plane and high wing Al has always been that for me all the years growing up building Comet and Giillows models.

I have an Sig 1/2 A handle for it with the string, not wires, so hopefully that makes it ok?  And yes, it is a flat bottom airfoil, with no symmetry.

    I would suggest just building it as designed might be better. One of the things you need to be able to handle is a few crashes, making the wing twice as long will cause it to be much more prone to damage on a crash.

    I am not sure what you are talking about here - is this a Guillows airplane, like,  a Cessna Skyhawk scale plane?   I wouldn't think that a good choice, either, as it is pretty fragile for crashing work. Despite the fact they might show you a CL conversion, it's not up to any crashing. Bear in mind, this will be going 30-40-50 mph into the ground a few times. Or more than a few times.  And the "high wing" is not a generally favorable characteristic and not more stable for CL than a mid-wing design, and the asymmetrical airfoil will be much more troublesome than a flat plate or symmetrical airfoil,

     I might suggest something a lot simpler and much sturdier. One of the advantages that 1/2A airplanes - 1/2A CL airplanes, that is - is that they can fly about as well as possible AND still be  strong enough to take a lot of crashing. Fly them over grass and they will survive. Converted FF airplanes certainly will not. Something like a CG Wizard, SIG Skyray (the 049 version) , etc. will get you past the "getting dizzy" and "losing your orientation" stage.

   Your handle and dacron lines are OK, they are pretty durable. They will also be *very short* which means the rotation rate will be very high.

       If I have misinterpreted, please clear it up. I am sure we are all very happy to help and can get you going, just let us know what you are planning.

   I also note your location as "South Texas" - if you can specify a bit better we can probably find someone nearby to help, particularly getting over the first few flights.

      Brett

Thank you, Brett!

We live in the Houston area and I am currently researching clubs that have C/L flying circles, but nothing solid yet.

As far as clarity on the plans go, my Uncle gave me these former and ribs sets, along with a plan, that he purchased somewhere on-line.  This is built with very light balsa framework and designed for rubber power.  I hate rubber power and love the site, sound and smell of small nitro engines :-)

So instead of throwing these in the trash, thought I could beef up the structure, extend the wing span, and make something useful out of it for C/L purposes.

But if this is simply folly and over ambitiousness on my part, please let me know and it will go to file 13.

A Sig Dewey Bird or Sky Ray appears to be what I need but since Sig is out of commission for an unknown (at least to me) period of time, thought I would make do with what I had before my sons and I fly the two Sig Shoestring Racers I made for them (and they look really nice, spent a lot of time on them and do no want to smash them up training the boys with them).

Does that help provide a bit more perspective?  Thanks again for your input!

      I think you are OK, but you definitely want to start with something else, if you haven't flown CL before. The converted FF models are way too fragile to start with. Houston has a very active group with numerous national-level competitors, and they should be able to get you going and maybe let you fly a trainer enough to make it safe to fly your model.

   The Shoestrings would be fine for early flights and you can get help to reduce the chances of a crash. Fly over grass and these small models will tolerate a lot of crashes.

     In case it wasn't clear, do not just extend the wing, that will just increase the likelihood of damage in a light crash, and not make it perform any better. This will be a roundy-round airplane, that is, it will just be able to fly level, probably.



     Brett

As far as clarity on the plans go, my Uncle gave me these former and ribs sets, along with a plan, that he purchased somewhere on-line.  This is built with very light balsa framework and designed for rubber power.  I hate rubber power and love the site, sound and smell of small nitro engines :-)

So instead of throwing these in the trash, thought I could beef up the structure, extend the wing span, and make something useful out of it for C/L purposes.

Egad!  No!  You'll just be disappointed if you try to turn a rubber powered plane into CL.  You're much better off starting with a kit that's designed for CL.  Save the pieces you have; sooner or later you'll meet someone who flies CL and free-flight; give the stuff to them.

As to high wings and CL -- high wings are great for RC and free flight, but don't help a CL plane much.  If you have adequate line tension that gives you all the roll and yaw stability you need -- high wings just complicate the control system.

Buy a kit, that's intended as a trainer.  If you have the space to fly it, get something that's powered with a 15 or bigger.  Unless you already know them inside and out, 049 engines can be extremely frustrating to run.  Something sized for a decent 15 should be much more reliable, and it won't spin you into the ground.

Thank you, Brett!

We live in the Houston area and I am currently researching clubs that have C/L flying circles, but nothing solid yet.

As far as clarity on the plans go, my Uncle gave me these former and ribs sets, along with a plan, that he purchased somewhere on-line.  This is built with very light balsa framework and designed for rubber power.  I hate rubber power and love the site, sound and smell of small nitro engines :-)

So instead of throwing these in the trash, thought I could beef up the structure, extend the wing span, and make something useful out of it for C/L purposes.

But if this is simply folly and over ambitiousness on my part, please let me know and it will go to file 13.

A Sig Dewey Bird or Sky Ray appears to be what I need but since Sig is out of commission for an unknown (at least to me) period of time, thought I would make do with what I had before my sons and I fly the two Sig Shoestring Racers I made for them (and they look really nice, spent a lot of time on them and do no want to smash them up training the boys with them).

Does that help provide a bit more perspective?  Thanks again for your input!

    I wouldn't throw the old parts away, you may want to build it as a free flight model, or even C/L scale. As the old saying goes, "Parts is parts!!" They can't take up that much room, and maybe even one of your kids may take an interest seeing as they are family heirlooms!
   My vote is nag on to them with as much provenance with them as possible.
  Type at you later,
   Dan McEntee