TwistStang goes on a diet

[Paul Taylor]

Well I never have been satisfied with the way my pig of a Twister has flown after the rebuild. It was already heavy and picked up a ton of weight on the rebuild. 52oz. !!!
It is not a real good flyer compared to other planes I have flown.  So tonight I pulled the engine and tank off and have started cutting wood. I am also going to sand off a lot of paint. It has about 6 or 8 coats of paint on the fuse that is wrapped in silkspan.

Anyone have an idea of what my target weight should be? Maybe give me something to shoot for?


The next time you see it, it will look a lot different. (I hope)
And maybe fly better.

Paul 

[Paul Taylor]

Thanks for the info Ty.
I will do my best to get it as light as I can. I will try a tougue muffler. Also this is a F-Twister. So I added 3 in to the fuse and made the stab bigger. Not sure I can get it that light but will work on it.

Paul

[Harleyman]

Sig Twister and Banshee are similar in size and construction.
My Banshee with metal tank and FP40 with stock muffler weighs 42 oz.
After you strip the paint off, consider this:  draw a center line on the very top and bottom of the fuse.  This is a reference line for additional sanding.  You can remove more wood from the top and bottom sides of the fuse being careful not to break that center line.
Make sense?

[Alan Hahn]

Here's my suggestion.
Remove everything which is removable and weigh each part, including the plane itself. Then look at what else exists in the same categories (lie differnent engine, tank, landing gear, wheels..... to see how much weight you might save by simply changing components---note I didn't say actually do it yet, but see what might be easily achieved. Lighter engine and muffler but original landing gear could be a few ounces, maybe more. Also are you running tailweight to balance the front end?

[Paul Taylor]

I am down from 52oz down to 48oz!!!   
I still have some more sanding to do and shape it some more. Getting all those layers of paint off might help too. I also took the bafel out of the muffler.
I thought about drilling holes in the landing gear but I fear it might make the gear bend when landing. I do make some hard landings at times.


What else can I do?

Thanks
Paul

[Paul Taylor]

Yea I use a ProZinger 12x4 cut down to a 11x4.

[Dennis Moritz]

You may have gotten some hard and heavy wood, if you built from a kit. Half inch square leading edges can vary an ounce or two in weight. Carving back the inside helps. Contest wood used in planking, a plus. When building from scratch it's possible to find a fairly light and stiff piece of half inch for making the fuse. Lots of kits err on the heavy and hard side when it comes to fuse wood. Especially true in older kits. My latest Twister came in at around 40 ounces with an FP40, tongue muffler, wingtips and half ribs. Light wheels and tongue muffler should lighten the front of your plane. Also, I like the idea of a wood prop.

Check the trim thoroughly. If you're outboard wing is low or up at any point in the pattern you're loosing lift and turning ability. If there's indication of a warp, check it out and correct. A few weekends back a friend with lots of CL experience helped me trimmed out an ARF Cardinal. We wound up removing nearly all the tip weight. A small outboard trim tab kept the wing level during insides. A half an ounce of tail weight also helped. The result was a much quicker turning stunt friendly bird.

You might consider adding wingtips even now. This can smooth out turbulence a bit and help wing lift. Resulting in a more responsive airplane. Is the airplane turning quickly enough? If the airplane stalls go to less line spacing or try adjusting the ratio of flap to elevator throw. Taking weight off the front, adding a bit of weight to the tail, quickens airplane response. Watch it tho. A cg that's too far back will make a touchy plane that won't groove. Trimming can turn a borderline dog into a nice flying usable comp plane.

[Perry Rose]

If it's that heavy is it worth the effort and time to lighten it? Ted Fancher's article on building the Twister states 35 to 40 ounces. I just framed up an F-Twister and it weights 32 ounces before finishing/covering. Monokote/Lusterkote/Fox .35. I figure 36 to 38 ounces ready to fly. I would save the wing and stab and build a new fuse. I actually did just that on my first Twister after a crash.
Perry Rose

[Paul Taylor]

If it's that heavy is it worth the effort and time to lighten it? Ted Fancher's article on building the Twister states 35 to 40 ounces. I just framed up an F-Twister and it weights 32 ounces before finishing/covering. Monokote/Lusterkote/Fox .35. I figure 36 to 38 ounces ready to fly. I would save the wing and stab and build a new fuse. I actually did just that on my first Twister after a crash.
Perry Rose

Thanks for the info Ron.
I have already crashed and repaired this plane more then once. The first crash had me glueing the wing back together and then I sheeted the LE back to the spar. I also added sheeting to the ends of the wing and more sheeting on the TE. I also added cap strips to the ribs. So my guess is my wing is heave also. Not much I can do to remove weight from it. I will shave as much as I can off the fuse and tail feathers. If I can get close to 45oz I will be happy. I am trying to get in touch with Randy Smith to get a tongue muffler that will save me 2oz alone. If I get it down to 45oz and it still flys bad, it will become a trainer for someone or a hanger queen.

As for your new F-Twister- I thought the plans call for at least a LA .40? Seems like the Fox 35 may not be enough engine for a F-Twister?
But then you build a light plane. You need to show us some pictures please.
Paul 

[Just One-eye]

The Twister wing is only 490 squares, and a Stunt Fox 35 is a reasonably good match to that size plane, as long as it weighs less than about 44 Ounces; it is, after all, the engine that the Twister was designed to fly with.  I've thought that the Noblers were as large a plane as the old Fox should be expected to handle, at approximately 525 squares (I know, TF's ads all said 550 squares, but that was incorrect).  Of course, I did fly a Skylark during 1965/67 with a Fox 35, and it had 560 squares, with a weight of 48 Ounces. 

My second Skylark, with an OS Max S 35, performed much better, even though it weighed 49 1/2 Ounces.

[Will Hinton]

Hi Guys,
The old flight instructor days leap out and make me write this - remember fellows, thrust (engine power) does not overcome weight, but rather overcomes drag.  Lift overcomes weight.  The four forces acting on an airplane are consistent in their overall affect on the flight characteristics and a bigger motor won't help an overweight ship.  Only weight loss will do that.
Will

[Alan Hahn]

Will,
What you say is true until you point the nose up! Then lift abandons you and all you have is thrust.

But the truth of what you say is lift gets you though the corner, and as long as the Lift/Drag ratio isn't too bad for the angle of attack you need to use to generate said lift, then you will have preserved much of the original velocity of the plane. That makes the engines job in lifting a lot easier. A lighter plane vs a heavier plane of the same tight will need a smaller AoA and  believe a better L/D ratio, so should keep more of its speed if both corners are identical.

[Will Hinton]

Alan,
You are right on.  The main thing I run into with an overweight plane (betcha you guys are shocked to think I ever built one!) is the potential mushing in the corner approaching the vertical climb for the squares.  I tend to tip stall my ships anyway and that corner spells death to the manuevor for me if I'm not careful.
Yes, lots and lots of POWER (Binford?) in the vertical is wonderful.  (Or maybe more judicious application of elevator for yours truly?)  Some day. 
Blessings,
Will