Weight wins out over power!

[RC Storick]

I took both my S6B and the Jet out tonight. I have been flying my Jet for the last couple weeks because I thought POWER was the way to go. I had been flying it so long I had forgotten what the sporty feeling the light planes give. So after flying both planes back to back tonight I have made the decision to fly the Super Marine at the NATS this year.

I did have some trim problems tonight. The problem I was having was the prop had lost its pitch and the most I could get out of the engine was a 5.6. The wind was blowing pretty good but it still pulled through OK. I think after the NATS I will retro fit the .75 in the nose of the 56oz Supermarine.

So survey says S6B!!!

[Steve Holt]

In Phil Granderson's article on the Diva, he commented on how when he switched from his PA airplane to his classic how much more he enjoyed flying the classic.  His direction with the Diva was to get full PA airplane performance in a slightly smaller, lighter airplane.  Diva power is a .36 on a pipe.
Steve

[the original Steve Smith]

I saw it for myself today!

I've been watching Bob fly the Jet and the Supermarine.  What a difference.  The Supermarine just "grooves" better and Bob flies sharper corners and smoother overall than with the Jet.

Good luck at the NATS with the Supermarine Bob. 

[Bill Little]

This is a classic example of the discussion we had a while back on airplane design with Ted.  We all have our preferences as to how we want a plane to fly!  And Robert, you have found your preference, which is good.

Some guys fly so nose heavy that another topflight pilot cannot fly the same plane; the same for tail heavy, overall weight, etc., etc..

I tend to go with the "lighter set ups" because that is what I am comfprtable with.  Now, what I've found is that I like a LIGHT plane with a BIG engine!  My Geo Juno is in the low-mid 50's and it now has a PA 61 in it.  Best set up so far for me.  I am working on two more "PAMPA" planes that I am looking to keep under 60 oz. and they will be powered by '61s on pipes.    I just don't like a plane that pulls hard at all.  (funny coming from a 6'2" ???lb. ex-middle linebacker, huh!)  I just really love the feel of a 36 oz. Ares on the ends of the lines and want my "big" planes to feel the same.

[Randy Powell]

I think it's a very good point. My current plane (project) is finally in the ballpark. I can actually fly a complete pattern on it, though it's still a bit too exciting. The problem is, the plane weighs about 68-69oz. Now, it's close to 770 square inches, so I thought it would be able to carry the weight OK. The engine, an OS46VF, seems to have plenty of power, but the plane is a dog. It's a dog, not because of the weight (I've had heavier planes that flew much better), but because of the design. It's largely a Bill Werwage wing with a fairly thin airfoil. The thing just doesn't have the carrying capacity for that sort of weight. If I can figure out a way to get 2 or 3 oz off the tail, then I can take the 5oz of lead out of the nose and get the thing down to around 62-63oz and it will probably fly OK. But as it is, it's a pig. I could probably up the pitch on the prop and increase from the 5.3 second laps I've flying to the 4.8-4.9 range and alleviate some of the problems, but certain not "fix" them.

If, on the other hand, I had used my favored airfoil (more like Ted's airfoils), I suspect that, while lighter would be better, it would fly just fine where it is.

I feel like it's a combination of design numbers, weight and available power. Lighter is better generally, but not always. I think there is a weight envelope for a particular design and power combination. Stay within the envelope and you have a good flying plane. Overweight creates certain problems while underweight creates a different set of issues.

[Bill Little]

Hi Randy,

No arguments at all about your "design" and th eongoing discussions. 

There are two distinct camps for the "weight" question, and both are from excellent flyers!  IT IS the dsign thoughts that go into the weight equation.

"I think you can build a stunt plane too light.  But I have never done it", Bob Hunt.

As you know, Bob and Billy design, and build, for the lightest weights they can.  I guess that is a statement some would argue, but it has come straight from them!

The USA-1 wing, as we discussed, was designed for airframes all up at less than 55 oz.  Billy's "big" Junars and his Geo XL were based on the USA-1 wing.  Those planes were in the sub 55 oz. range.   Even his Razorback Geo Bolt is, and that wing will carry much more weight!  My 54 oz. USA-1 had absolutely no "kite effects" in the wind, but again, it was designed to weigh in that area.  I would NOT have been as pleased with that plane if it had been 60 oz.  The design just would not have performed as well.  It's like the difference in a 36 oz. '59 Ares vs. a 44 oz '59 Ares.  I have flown both and the heavy one just would not perform.  Regardless of engine used.

So, all I'm saying is that there ARE (in agreement with you) design parameters that dictate the upper weight limit that a plane can fly at and do so successfully.

A Werwage/Hunt design had better be kept light, while a TP, PM or other such "more modern fatter" wing will carry much more weight.  Ask Bob Lampione about his 80 oz. plus PM!

My personal preference (and again "my") is for a light on the lines plane.  I have found out that a plane entering the 70 oz. weight area just pulls more than I like, and I trim to get light tension.  Some like the "heavy" feel.

Bill <><

[phil c]

I'd agree that weight wins over power, but low weight and even more power is better.

One of the weight arguments has been about trimming.  Brett Buck made a very good point.  If you have to add a couple ounce of weight to a 58 oz. plane to trim it properly, do it.  The improvement in flying from getting the trim just right will far outweigh a couple percent extra weight.

The other weight argument, as Bill Little says, is in the building.  If you take a proven design and build it 8-10 ounces lighter you no longer have a proven design.  A lot of other things have to change to fly well at the lighter weight.  If the light weight means the plane isn't as stiff as the original, it will not fly as well.  Too much weight reduction will also let the structure wear out more quickly.  A design that flew 1000+ flights for the designer may only be good for a couple hundred if it is built a lot lighter.

Sparky's building is a great lesson for everyone.  If the underlying structure is built up nice and level by careful fitting, you'll need barely any filler and primer to get a nice base for paint.  And a level surface means the color coats can be thinner and lighter.

Too much glue, too much epoxy, too much filler, and not weighing every piece of balsa and getting just the right grain, stiffness, weight are all killers for overweight planes.

[Randy Powell]

Phil and Bill,

I mostly agree. The wing on my plane is USA-1ish. But not a USA-1. The wing is fatter (about 3%) and has much bigger flaps. I'd imagine that a weight in the range of 57-60oz would be fine. Much more than that and it's starts to wallow. I think the ideal weight for a plane is likely design dependent. It's been proven around here repeatedly that the ideal weight for an Impact is 60-62oz. You can get away with as much a 66-67oz, but after that it's starts to have pretty bad problems. Many around here have been built at 70+ ounces and they just don't fly very well. A few have been built at near 50oz too. They also don't fly very well. They are unpredictable and it's hard to get them to fly the same twice in a row (and yes they have very stiff structures). If you add weight to them near the CG, they start to get better. The ideal weight for the design envelop is right on the 60-62oz mark.

I just finished framing up a new plane. It's 626 square inches. I built one before that was upwards of 80oz. It was, as you can imagine, quite a dog. The new one is on track to weigh about 50oz. Should be better.

On the other hand, I had a lot of experience with high aspect ratio planes with very fat airfoils and blunt leading edges. I had several that were around 650 squre inches, anywhere from 7 to 1 aspect ratio to as much as 9 to 1 AR. Most were around 60oz but one one about 48oz (a profile) and two were in the 70-73oz range. without a doubt, the heavier planes flew better. The light jobs just wouldn't turn consistently. I suspect, now that I've built a bunch of them, that they just generated too much lift in the corners and in any sort of wind made them unpredictable. The best was the last one that was right on 70oz. Great flying plane.