2BFlying

Thanks to all

I appreciate all the helpful tips and suggestions that were given to me during my
TWISTER construction. It finally made it in the air Sunday evening, a great day for flying around here. Here are the results:

I am using an R/C motor, a TT GP42. I have posted pics of my throttle lock on the engine and it worked excellent, at about 7/8 throttle.

Flight 1
Leadouts about center on main spar, slightly rich on needle setting. Got off the ground fine and was just putting in level laps to see how the controls reacted. About 3 minutes into the flight I went too low and landing gear hit and prop broke. No damage at all, picked up the wheels and put them back on. This was an 11-5 prop, didn't have any more. Line tension great on level, but dropped off with elevation.

Flight 2
Went to 12-6 prop, no low pitches in the box. Refueled and made no change to anything, took off. Good flight, almost 6 minutes, seemed sluggish in turning but no hunting, wingovers okay, but still line tension drops the higher I go. Prop definitely too much. No loops or nothing yet.

Flight 3
Changed to 10-6 prop. Moved elevator rod up one hole for more deflection. Went 5 clicks richer on NV. By the way, running Uniflow with muffler pressure, goes slightly lean about 2 laps before shutdown. Refueled and took off. Also moved leadouts forward 1/2 inch. WOW This thing took of and line tension was great, even flying at 45 degree angle. A little fast, 5.0 sec/lap. But it pulled even going vertical. Controls very responsive, feels like my planes of old. Okay here we go. Big lazy loop Piece of cake. Next lap another. Wingover. Up and downs. Another loop, tighter this time. Okay, I'm at 5 minutes into the flight, Level for a while. This thing really moves going level. No wing dipping or wobble. Gas gone, nice 2 wheel landind and roll on the pavement. I'm flying at my work. Big paved parking lot.

Flight 4
Refuel and go 1 click closed on NV. Takeoff. Afew level laps. Loop. Another and another. Big 1/2 loop and invert. 4-5 laps inverted. Outside to upright, 1/2 circle back to inverted.go upright and high outside loop,into figure 8. Motor never missing a beat, sounds good. Steady pull from it, even vertical. Wingover to inverted, and so on. Time's up, motor goes slightly lean, 2 laps later. another landing.

Flight 5
No changes it's flying really well and sun is about to go down. Parking lot lights are coming on. I really wring it out , flight times are now 6 to 6 1/4 minutes.

That is the most fun I've had in a long time. I'm flying on 60 foot lines and there was a gentle breeze. I will get some more props this week, my 12.25 by 3.75 was at the house on an R/C plane, and I wanted to try that one. But a good day was had by all.

My flying buddy couldn't make it so my wife went with me. It took a lot of explaining when I told her she was going to be the STOOGE, didn't think I was going to get out of that one.

Thanks to everyone. One of the joys of life is 2 B Flying.

kdheath

Well done, RW! Sounds like it was a total blast. How does your wife feel about being blasted with castor oil exhaust?

Didn't know you were running the 42. That's a fine stunt motor. I doubt that you'll be able to make it happy with a 12 inch prop. The 42 will want to run in a rich 2-cycle, as you noted, without much of a break. Some other possible props might be: APC 11-4, APC 11.5-4.5, Zinger 11-4 0r 11-5, Zinger Pro 11-4 or -5. I run a Zinger 11-4 (with thinned blades, rounded tip and cleaned up LE) on my Neumann Tower 40. Pulls a 53 oz Pathfinder with authority.

Ryan and I were all lined up to go out Sunday and the rains came and went and came and went...then the wind blew. Bummer.

Congrats again and welcome back!

Kelvin

2BFlying

I'm definitely going to pick up some props this week. Wish i hadn't trashed my 11-5, it seemed pretty good with that one. I think 11-4 or 11-5 would be the way to go. It is definitely fast in level flight and I need to slow it down some.

On my 4th flight I removed the hose for muffler pressure and it didn't change anything. Ran the same with the uniflow vent facing into the prop blast.

I can get more RPM out of the motor, it's not close to wide open. But for now I will stay with what I have until I get some props. Does Leonard carry APC props? I like them over MA brand. And for the price, they are hard to beat. I don't want to tie a lot of money up on props. I can't find his tel. no. to call and order. I wanted to do some business with SSW.

Yeah, my wife did mention the oily smell on her before we got home. Still haven't gotten myself out of the doghouse for calling her a stooge.

2BFlying

kd

I'll keep adding tidbits of info as I go thru my night here at work. I have absolutely no idea where my CG is on this plane rught now. I remember working with it when it was finished, but have forgotten where it is.

I made a tongue muffler out of aluminum for it, around 20 grams, I think, the original muffler weighed 85 from Thunder Tiger.

So what will playing with the CG do for me? Will more nose weight make it turn quicker? I improved the turning by moving my rod on the control horn for more deflection. I might try reducing the flap movement next.

kdheath

I'm in over my head a little with these adjustments. Ther rate of turn is effected by at least four things: the elevator-flap ratio, the CG, the total throw of the surfaces, and the line spacing at the handle.

But based on what I do know, I would set the flaps and elevator in a 1:1 ratio-same amount of throw on both. Some of the classic planes work better with the flaps a little slower, like 2:3 ratio. But the Twister should be OK at 1:1.

A good starting CG is right at the wing spar. If it is a little "jumpy", try adding a little nose weight until it grooves in level flight. Then you can adjust the turn by changing the throw of the surfaces or adjusting the line spacing at the handle.

Typically, 30 degrees of control movement is plenty for our purposes. A lot of older plans show 45 degrees, but it's really too much for stunt. I think the surfaces on my Pathfinder move 26 degees and it turns very nicely. Too much motion just stalls the surface and defeats your purpose.

The contemporary theory is that you make the plane really stable in pitch, then add enough tail volumn to make it turn a square corner. If it overshoots the corners, narrow the handle spacing or back off the control sesitivity until you can make a tight corner without overshooting.

One of the Fancher mods to the Twister is to enlarge the horizontal tail about 20% or so, and lengthen the fuselage 2 inches at the rear. The change brings it more into line with current thinking. Not a miracle worker, but it will make the Twister fly a bit smoother and with more authority.

FWIW, most nice stunt ships now use a 4 inch bellcrank rather than the 3 inch that is so common. It gives greater leverage, and guys describe it as being like power steering.

Oh yeah, don't run the engine for peak RPM. If you have good airspeed and tension over the top, you probably don't need more speed. The problem with these Schneurle RC motors in stunt planes isn't a shortage of HP, it's keeping the power regulated. If it tries to run away with you (going way lean and "winding up" in loops), you may need a smaller venturi or more restrictive muffler. In fact, an easy way to play with the CG is to go to the stock muffler and see what the weight and the extra muffling do to you.

Gads, getting tired from thinking too much...

jehold66203

That is what makes it so much fun flying model airplanes. Expeirmenting with things. The engine going a little lean the last two laps is great. It is a warning sign not to do anything but get ready for landing. Also if you are happy with the way a plane flies and handles, why change anything? DOC Holliday

2BFlying

Hello DOC

Yes, I am really pleased with the way the first flights went. This is my first flapped bird and I just am interested in the differences between my non-flapped stuff I flew in the 60's. My RINGMASTER with a McCoy29 (42 span) would turn tighter than the TWISTER, but I have just started to work with it. I should be able to get my corners a little more square, I think. But I have something to work with.

When my flying partner goes with me, he will be able to tell me more about the plane's attitude while flying from a perspective outside the circle. I think this is a good first plane and I plan on putting a lot of time on it. I want to go with a built-up fuselage for my next one, but time is going to be the problem. I am covered up at work right now, and we just got 2 new guys in, so they will take 1-2 months to get up to some sort of speed. I am going to get something from SSW that is a pretty basic design and build it. I even want to try doping this one, make it a little better than my TWISTER.

You are right, its all about having fun. I doubt I'll ever compete, but it would be nice to have somebody to fly with and compare notes. All I learn is what you guys on the forum tell about.

2BFlying

Hey kd

You said you had a Pathfinder. What kind of plane is it? Full fuse? Was it a pretty straightforward build? You have me interested. Does it fly well? I have a K&B 40 something that I can machine venturis for rather easily. It is an R/C engine but it really runs well. The carb mount on the TT GP 42 will be a little complicated to machine to accept a venturi, but the reason I used it was it is absolutely dependable. Haven't flown the K&B that much.

Jim Thomerson

If you are flying a stock Twister, the CG should be at 15% Mean Aerodynamic Chord. I'm too lazy to go out to the shop and check, but I think that is 1 5/8 back of the leading edge (maybe 1 3/4).,rather ahead of where it is shown on the plans. If you are flying off grass you will need to move your landing gear as far forward as your CG is from where it is shown. Off blacktop, the plan landing gear position is perfect. If you are loosing tension up high, your leadouts are too far back. Move them forward 1/8 in at a time until the airplane flies to suit you. A Twister with the CG in that position will fly a very nice stunt pattern.

Jim

kdheath

RW, the PF is a Brodak kit design by Gordan Delaney. Terrific flyer and a pretty easy build. The structure is kind of like a big, light Twister. There is an ARF/ARC version somewhere in the Brodak pipeline. I have the John Miller plans for the original full fuselage PF, too, and it's a beaut. CAD drawn, plotter printed plans.

Here's the SSW thread about PFs- lots of photos, mine is the red and cream one about 2/3 the way down with AMA 8607 on the wing. Just finished repairing it after last fall's crash...
http://www.clstunt.com/htdocs/dcforu...ID1/11107.html
Sorry, I forgot to add the link....

Has the SSW Tower 40, Brodak uniflow tank, and Tom Morris control parts. Monokote and Rustoleum. Nice nice to fly! Lone Star Balsa has the kit-last time I looked- for $63. Cheap.

2BFlying

Hello Jim

I did move the leadouts forward on flight 3, I think, and it DID make a difference. It may not have been 1/2 inch but I could tell the difference. You are the one that gave me the instructions back in December about how to build the adjustable leadout setup and it works great. I posted a pic of the result somewhere. I really appreciate your input. It worked.

kd, I did what you said to do in a post about line tension and it worked,too. It was the difference between night and day. Thanks for your help.

So the PF is a profile, but a big one. Sounds good to me. That's about my price range for now, I am really not ready to go the 125 dollar and up stuff just yet for a kit. Yes, they sound really great, but I have to learn to walk before I can run.

But I have one question for tonight. Why was there no difference in my engine performance between running muffler pressure and then going to just straight uniflow, or airstream, pressure. Was my muffler tap of too low a pressure? I don't know. I thought there should have been some difference.

Jim Thomerson

There should have been a difference. I have had the muffler line come off in flight a couple of times and the engine went noticeably lean. I don't have a good answer; maybe a leak in the tank? Even so there should be a difference.

Jim

kdheath

I agree. The engine should go lean if the pressure line is taken off and the needle valve isn't adjusted. But I've seen varying results. Some quite dramatic and others not much change.

You don't have any real control over the amount of pressure the muffler produces. Maybe the size of the hole in the tap would make some difference, but I wouldn't think it would be much. And the actual pressure isn't all that high anyway. I don't know that anyone has a real answer to the question. Mostly we just go with what works....I have good luck with the muffler pressure, but then I don't know any better.

Yeah, I think the PF is a real bargain, too. Big (620 sq inches) and light, flies fine on a garden variety motor. OS LA 46 is another good way to go. I saw at least one with a 40 four stroke. Only bugs I've seen are that they are a little vulnerable in high winds and the tricycle landing gear takes some extra care when flying off grass. Not much prop clearance, either. But I've been able to work around those with bigger wheels and 11" props. When you get the takeoff and landing right, they're really pretty. Last night I made up an Al Rabe style jig to assemble my new PF and it looks like it will be among the straighter things I've built. That jig is a great idea.

2BFlying

Jim

I got to checking my CG today with the same jig that I use for my R/C planes and it looks like my CG on the Twister is about 1 inch from the leading edge. My Jig is just a flat plate with two one inch dowels, rounded at the top and far enought apart to catch the bottom side of the wing at the sheeting on each side if the fuselage. I don't balance it upside down, do I?

Jim Thomerson

If it is not cornering and turning tight enough to suit you, I'd suggest moving the GC back 1/8 in at a time. If it starts getting squirrelly on you move the leadouts back as well. The whole secret of trimming is to make small changes so you don't mess things up and have a repair job to do.

Jim

kdheath

One inch from the LE sounds a little nose-heavy to me. But I don't have Twister plans handy to check. Jim is right on-move the CG back a tiny bit at a time and see what you think. I don't think it matters whether you check it right side up or inverted. Do whichever is more comfortable. Some builders include a weight box or some way to attach weight to the tail for the purpose of trimming the CG.

2BFlying

That's what I have done. I drilled a5/16 hole straight up thru the bottom right next to the tail wheel about 1 inch deep and I can put lead weight in it and put a plug back in. You can't tell it's there unless you look hard.

I rechecked the balance and the CG did move back about 1/2 in. I'm going to try from there and adjust a little at a time.

Now I know why I enjoyed CL so much. You can make changes and go right back and immediately fly. My RC stuff has to be charged between flights and eventually after 4-5 times you are pretty much done for the day unless you bring spare battery packs for everything. After 4 flights I worry about my voltage and it getting low enough to lose control or response. Especially the Chipmunk with flaps and retracts. They take a lot of juice. Happy flying