I'm building an outstanding version of the CAP 232 from www.stevensaero.com

This is an electric airplane with 240 squares and flying weight of 15 to 20 ounces. Construction is exactly like the rubber free-flight we used to build. VERY light, but adequate, for excellent performance, even as an electric.

I hope to make mine come in at 12 ounces and use a Norvel .061. The mount is also going to have provision for a Norvel .074,,, just in case I need it. :devious:

The plans call for the usual right thrust but there is no down thrust. A call to Bill Stevens yielded the information that this plane doesn't need downthrust and in fact, tends to pitch up when the power is taken off rapidly,,, so that some are even putting in a little UPthrust. This all seems counterintuitive to me.

I do know how downthrust works and why its needed in many cases. A search on the net shows that Bill's assertion is generally true. I'm also converting a small electric ARF Extra 330. this one has the usual right thrust but also includes the expected downthrust. Both planes have similar force arrangements although the Extra has a semi-symmetrical airfoil while the CAP is fully symmetrical. In my experience a fully symmetrical airfoil doesn't necessarily negate the need for downthrust. Or am I wrong?

Can anyone confirm that all CAPs don;t need downthrust? Why? Any other comments?

Caps often need up thrust because of the high thrust line. Most of the drag of the airplane comes from below the thrust line, hence the up thrust to compensate for this. Relative to caps, Extras have a lower engine and higher wings so something between 0 or some down thrust is what is seen.

Hope this helps.

You ain't seen a tip stall 'til you've flown a Cap! Be warned! Extremely sensitive to elevator when going slow... and yours is a small twitchy version.
I had a lot of fun with this one.. 1/4 scale Byron, 35cc gas motor.
Vanished in a foam snowstorm one day.... (sob!)

3D Joy,

Aha, that makes sense. Something like a seaplane with a pod on top for the engine. Low center of drag = pitching down, = need for some upthrust. Many, many thanks for that.

Hey Paul,

Twitchy? Well, that's what 1/2A USED to be,,, in the old days with heavy radios and weak engines. Many of these needed full bore just to stay in the air and many were almost near the edge of a stall just to maintain altitude. NO MORE.

With light radios, batteries and powerful engines, I've got 1/2A planes flying just like the big stuff,,, and in some respects, better. :devious:

My first was an Ugly Stik with 34" span and 14 ounces. With a Norvel .061, it can do anything including touch and goes which transition immediately into stall turns, inverted all day, spins, inside and outside loops, etc. etc. Take off from grass fields are no problem, to boot. You can see this one in the May 97 issue of Flying Models, titled "Kit Bashing 1/2A Carbs" Follow up article was "Kit Bashing 1/2A Engines" in the August 01 issue. Finally, you can see a Norvel .074 powered Tsunami in the latest issue of FM in Randy Randolph's SMALL Steps column. Like the Stik, the Tsunami was built from reduced plans. They were built to exact scale, so to speak, using contest wood and light covering. I use a field charger and 150 mAh packs in the plane. Micro servos tops it all off for a very light airplane. The trick to making exact copies in 1/2A that perform just like the original is to make it LIGHT and have a powerful engine that throttles reliably. With modifications to the Norvel, I can idle all day and get perfect, no hesitation transition.

The Tsunami has unlimited verticals from take off and will do it all, including knife edge at 10 feet down the length of the runway.

Pardon my enthusiasm, but done right, the small stuff CAN compete. The CAP 232 that I'm building from StevensAero is truly unique with laser cutting and very, very light construction. A bit of beefing up for glow is all it takes.

Thanks for the tip stall warning though. I suspect, maybe, that this might be due, at least in part, to a bit of a heavy wing loading. Then again, we DO want snap capability,,, don't we?

Thanks for the input guys, I feel like I've got a tiger by the tail that won't disappoint.

I have a 1/8 scale Extra 230 that will be ready to sell in the next few months. Here is a pic of it. The thrust line is dead center of the wing on it so that should be nice for what some of you are looking for.

Clean fast snap performance comes with a price keep the wing loading down and your throws conservative and you'll have a blast. This little guy minds it's manners relative to wing loading.

Just to clarify, Many pilots of larger IC powered 232's that I have spoke with felt the need for a bit of up thrust. On this little 1:8 scale 232 I have yet to find a thrustline that works better then dead zero.... unless you run the semi-symmetric wing. I would be curious to hear how it goes for you.

12oz - now that is gonna be a hoot! Thanks for the feedback.

-Bill

Bill,

Yes, 12 ounces will be something to behold. Slow going (my fault) but the fuse and tail are built but not covered. Total weight, a whopping two ounces. That's even with a bit of extra sheeting and other bits and pieces to reinforce just for the bang, bang of an IC engine. The wing ought to be no more than that. So, we're starting at four onces for the airframe. Engine, 1.75 ounces, Radio, 2 ounces. Gear, covering, control rods, maybe 2-3 ounces.

Twelve ounces should be about achievable. Can't wait. Will keep everyone posted.

That sounds exciting! - 12oz in the thick air of low alt... life should be good.

-Bill

Yes,

In some parts of the world they call it Nirvana. Say, that sounds like a good name for an airplane.

Andy,

So far the lightest I can muster E-Powered is 14.5oz - 8.5oz / Sq.'

It's no slouch either - vertical is unlimited - If you can get it down to 12 oz you will be in for a real treat! I have been flying this prototype based on the 232 wing E-Powered the airframe weighs in at 10.25 oz and 13.125 oz with the Battery RTF - that is 7.7oz / Sq.' - Again unlimited vertical and a very nice flight envelope.

BTW your PTEG cowl was a bit delayed but it has been sent off - you should have it within the week.

-Bill

Thanks Bill,

I'm loath to admit it, but at 14.5 ounces and the higher efficiency of a large, electric prop, your version just might be the better performer. At least in certain aspects.

That's where, perhaps, a diesel may be a better choice. Have done up a dieselized Norvel. It's going to be interesting comparing glow to diesel on this plane.

Still slow going but the wing is done. Darn near was able to build it in my lap. Amazing, with perfect parts fit and everything lines up and comes out straight. I did, however, sheet the center section and just the top of the wing forward of the spar with 1/32" contest wood. Again, only to resist the vibration of the engine. A few bits and pieces here and there for nylon bolts and it sure looks good. Many thanks for a remarkable kit.