F-Twister photos

The airplane weighs 38 ounces like you see it in the the picture. It is a little bit tail heavy. I placed 4 pennies on the nose to make it balance on the spars. It is balanced on the wooden blocks you see in the picture. The wing tips are solid balsa and a lot heaver than I wanted but I had to scrafice looks for weight. I would like to cover it with something other than monocote but I don't know what to use other than silkspan. I am not sure how much weight the monocote will add, 3/4 of the weight will be behind the spar so I need to cut some holes in the elevator and stabilizer and try to reduce the weight a few ounces. All balsa is not created equal the 1/4" balsa on the elevator, stabilizer and fin are as hard and heavy as #2 pine, its all I had so I used it. I will cover the entire airplane with monocote except the tail then cut enough holes in the elevator, stab, fin to make it balance. The fuel tank will hold 6 ounces of fuel. I plan to put only about 4 ounces of fuel in the fuel tank for this OS 25 engine. I have a 5 ounce and 4 ounce tank I can swap out. If I ever decide to use a different engine I may need more fuel. The 1/4" wing spars are made of spruce. I put the stock muffle on the OS Max 25LA engine for nose weight. I have misplaced my paper that tells me how much the muffle weights. I think I can reduce the weight a little more by removing the muffle and cutting more weight off the tail. I have aluminum engine mounts so I can change the engine without drilling new holes in the airplane. I built the entire airplane with a 1 ounce bottle of CA glue an I still have 1/4" of glue left in the bottle. The twister kit I built about 5 years ago had 3 bottles of glue in it. This is not the prop I plan to use. I tested the engine and it will turn an 11x4 prop so I think I will try a 12x4 prop next. I think the first test flight will be a 10x4 prop. I noticed the fuselage was not very stiff and the tail twisted back and forth very easy until I glued on the canopy. I guess the CA glue made it stiffer. I think its fine now but if I need to make it stiffer I can probably put a coating of CA glue on the bottom side of the fuselage to make it stiffer. The aluminum landing gear weighs 33 grams. The wheels added some needed nose weight too. I still need to add a tail wheel and linkage wire bracket. I have been too busy to work on it as much as I would like. Normally when I start a project like this I wake up early thinking about it so I get up 4am start working, skip lunch, skip dinner, work to midnight, in a few days its finished. I didn't work in it all week. Not sure I will get to work on it much this weekend.

Gary:

Nice work.

Round the nose as you have done the aft of the fuselage cover with fiberglass and epoxy, will look better, add strength, and weight. Move the engine as far forward as you can before cutting holes in the stab. If you still need weight an APC prop will weigh about 1 to 1.2 oz more than the wood prop.

With the longer tail moment you should be able to use a little more rearward CG which will save a few grams more.

Let us see the final results.

Gary,
Very nice!!! I hope to start one this winter. So far I am winning one on ebay. I hope folks don't get clicker happy.
Can you email me a close up picture of how you attached the engine to the pads? Are they tapped?

Thanks
Paul

Uhmmm..

Why not cut the tips off and hollow then with a ball cutter, attached to a D-tool?. You can hollow the tips out till you can see light through them, w/o hurting anything.

Is your center sheeting overhanging the ribs? If so, sand it flush and save a few grams!

Also, round off the TE and flap tips to match the shape of the wing tip.

It looks as if you still have a BUNCH of sanding to do! If you're tail heavy now, every gram shaved off will help later.

You could also save some weight (More than you might think.) by cutting away the center of the fuse blank and, after adding a few ribs, sheeting it with 1/16th balsa or 164 ply. That will also stiffen up your fuselage a lot.

Check out "Building a better profile" On the PAMPA web site for more details.

BIGS

PS: Did you weigh your wood before starting this project? Sounds like substandard materials to me but maybe you started with too short a nose for that engine. You could allways swap to something a bit heavier.

>Gary,
>Very nice!!! I hope to start one this winter. So far I am
>winning one on ebay.

Sorry I ran the price up a few dollars. I bid $25.00 on that twister kit when it was first listed. I bid $25.00 on every twister kit I see haven't won one yet. Thats okay I only got about $10.00 worth of wood in this scratch built airplane so far.

>I hope folks don't get clicker happy.
>Can you email me a close up picture of how you attached the
>engine to the pads? Are they tapped?

The engine is attached to aluminum plates. The aluminum plates are 1/4" x 1/2" x 2" long. Engine holes are .555" center to center tapped 4-40. Aluminum plates are attached to the fuselage with 4-40 by 1" long SHCS (bolts).

>
>Thanks
>Paul
.

>The airplane weighs 38 ounces like you see it in the the
>picture. It is a little bit tail heavy. I placed 4 pennies
>on the nose to make it balance on the spars. It is balanced
>on the wooden blocks you see in the picture. The wing tips
>are solid balsa and a lot heaver than I wanted but I had to
>scrafice looks for weight. I would like to cover it with
>something other than monocote but I don't know what to use
>other than silkspan. I am not sure how much weight the
>monocote will add, 3/4 of the weight will be behind the spar
>so I need to cut some holes in the elevator and stabilizer
>and try to reduce the weight a few ounces. All balsa is not
>created equal the 1/4" balsa on the elevator, stabilizer and
>fin are as hard and heavy as #2 pine, its all I had so I

Gary;

38 ounces less finish is getting a bit heavy for the LA 25. After flying my FT with an FP 25 and an LA 25, I am rethinking what should go in the nose. The LA 25 will work if you keep the ship very light and the weather is right. Throw in some wind, elevation, etc, and it gets a little challenging. My next FT will have something with a little more grunt in the nose. Me thinks either an FP or LA 40, or perhaps a Brodak 40 will do the trick nicely.

You are faced with a plane that is already tail heavy. It will get worse as you finish. You will have to add weight to the nose to get it to balance up right. If you have to add weight, you might as well add power. So, why not look around for a used LA 40 to put in the nose, and use the LA 25 in something like a Flite Streak or something else you might build in the range of 400-450 sqi (and kept light).

The longer tail moment means that you need to keep your stab/elevator/rudder as light as possible. I would also suggest keeping control movements to a minimum while trimming.

V/r

Fred has a good solution for your problem. My F/Twister has a modified Tower .40 engine, and weighs 42 oz. if I remember correctly. It really flies well, but likes to fly about 4.75 sec. laps on 60 ft. lines. I am using 63 ft. lines at this time to slow the laps down some.

Mine will have an OS 35 FP, boost port filled, swinging a 12-5 prop. Should be enough power... I'm assuming mine will end up on the heavy side, but hopefully not as porky as my Smoothie. I'd have some more pictures up by now, but I did a dumb thing... I made the outboard flap the same size as the inboard one... forgot to continually consult the plan... now I have to make a new one before continuing, but I'm also getting snagged in "home improvement" projects now. As far as I'm concerned, the best home improvement would be to hang planes all over the walls, but for some reason, the wife has other ideas...

>Mine will have an OS 35 FP, boost port filled, swinging a
>12-5 prop. Should be enough power... I'm assuming mine will
>end up on the heavy side, but hopefully not as porky as my
>Smoothie. I'd have some more pictures up by now, but I did
>a dumb thing... I made the outboard flap the same size as
>the inboard one... forgot to continually consult the plan...

Tim;

Fahgetaboutit. The stock Twister has identically sized flaps and flies fine. The flap is a little "tweak" that most folks just won't need.

Put the plane in the air (or get it ready for spring).

V/r

Hi Tim:

It will be PLENTY of power...but I suspect that over time, you will learn that the 12" prop will do funky things on that small a plane.

The thrust will get you out of alot of jams however. When you get to the point of trying to smooth out the rough edges of your pattern is when you will notice the problems of the gyroscopic effects of that big prop.

FWIW

The OS 25LA does seem a bit small but I am willing to try it because that is what it shows on the plans, others have used this engine and it works, and I have a Sterling Ringmaster and Flite Streak that fly good with this engine. I also have an OS 25 FX that I can use. I have 3 new OS 40LA engines, 2 OS 46LA engines, 1 torpedo 40, 2 Fox 36X one new with a muffler, all possibilities. It might be fun to try the Torpedo 40 on this airplane. I am hoping I can make this airplane fly very slow and do the manovers like something is holding it up.

I just came from the hobby store. Econokote is $8.99 a roll, Monocoat is $22.99 a roll. I think I am paying for the name. They have the color I want only in Monocoat so I did not buy anything.

Now you wonder why I don't buy Monokote at the hobby shop anymore. Tower has much better prices. DOC

>The OS 25LA does seem a bit small but I am willing to try it
>because that is what it shows on the plans, others have used
>this engine and it works, and I have a Sterling Ringmaster
>and Flite Streak that fly good with this engine. I also
>have an OS 25 FX that I can use. I have 3 new OS 40LA
>engines, 2 OS 46LA engines, 1 torpedo 40, 2 Fox 36X one new
>with a muffler, all possibilities. It might be fun to try
>the Torpedo 40 on this airplane. I am hoping I can make
>this airplane fly very slow and do the manovers like
>something is holding it up.

Gary;

As I did the plans, and I have flown a couple of the ships, I can tell you now that your unfinished weight is pushing the max as to what the 25LA can haul. Add a finish, and you will have trouble. My scratch built FT with a 25LA came in at 37 ounces - finished. On windy days I had trouble. I put an LA 40 in it, retrimmed, and was able to keep tighter lines. I ended up using an APC 12.25 x 3.75 trimmed down to 11.25 inches. You might as well set yourself up for success now.

But, what the heck. You may just need to find out for yourself.

Best of luck.

V/r

>I just came from the hobby store. Econokote is $8.99 a
>roll, Monocoat is $22.99 a roll. I think I am paying for
>the name. They have the color I want only in Monocoat so I
>did not buy anything.

Gary;

While I hate to pay the price for Monocoat, I have learned the hard way that for a colored film, it is about the best that's out there. Back when I lived in Clarksville (about 50 miles west of where you live now)in the early 1980s, I built a couple of Twisters and covered them with one of the lower cost films. It was all right in cool weather, but we know just how hot it can get in central and western Tennessee in the summer. To say the film sagged is an understatement. It also peeled, delaminated, and did everything else short of self immolation. I ended up pulling the covering off and going with silkspan and dope.

Hard lesson learned: If you are going through the effort to build a ship, you might as well spend the additional $10 and cover it with a good film (if film is your choice) that will hold up. I have found nothing with color in it that comes close to Monocoat.

Perhaps someone else has a better colored film covering. If so, I am always interested in finding out what it is.

V/r

I have been looking at this design lately because I was so impressed by a standard Twister which I flew. I downloaded Ted's article from the Aeromaniacs web site, see my post below under "F-Twister.....I give up....etc.". I notice Ted used "Supercote" and said it was good. He also says a Fairlead (which is apparently an eyelet half way along the fus to brace the pushrod) is essential. I notice you don't seem to have one. It may be worth fitting one.
The std. Twister I flew had a Fox 35 with standard heavy Fox muffler, and certainly did not lack power. I read that a 25 FP or LA is equal to or better than a Fox 35, so I'm a bit puzzled about now hearing that the 25's may be a bit marginal.

I'm flying the FT version from Ted's original series of MA articles. Covered and painted, mine weighs 32.5oz with an FP 25 mounted but no muffler, prop or tank. I built it from a stock Sig Twister kit and it has been crash repaired once.

Finish is fiberglass cloth on the fuse/vertical fin with LusterKote rattlecan spray finish and UltraKote on the wings and stab/elevator.

I've been flying it with the stock OS muffler, a Tornado 9-4 prop and Sullivan 4oz plastic R/C tank on uniflow. I added a Prather 1/2oz prop washer to achieve the desired CG.

I've not flown it in heavier winds but on 58'x.015" lines in light to moderate stuff it does commendably well. Engine runs have been VERY consistent. I think I was getting 4.6 to 4.7 lap times.

>The std. Twister I flew had a Fox 35 with standard heavy Fox
>muffler, and certainly did not lack power. I read that a 25
>FP or LA is equal to or better than a Fox 35, so I'm a bit
>puzzled about now hearing that the 25's may be a bit
>marginal.

Ian;

I have flown the venerable stock Twister with the Fox 35, Fox 36, Enya 35, OS Max-S 30 and 35, as well as the OS 25F and FP. All worked and had sufficient power for 58-60' lines, but I had the most trouble out of the Foxes due to vibration.

When I did the plans for the FT, I wanted to show an engine that is currently in production. None of those mentioned above are. So, after picking up a 25LA, I decided to try it on a FT, and added it to the plans. Since that time I have owned two 25LAs. My opinion of them is that they are a fine engine, but they don't have the ponies of the 25FP. My 25LA ship had some real trouble in the wind - even with 58' lines. So, I picked up a used 40LA, put a venturi and NVA in it, replaced the tank, retrimmed, etc, and went back out with 60' lines. Much better. Overall weight increase was 2 ounces, but the Twister wing can handle it. What it did give me was sufficient thrust for windy conditions. I could probably add a couple of feet of line length and still be fine.

The FT will pick up a couple ounces due to the nose doublers and lengthened fuse. That may push the ship over the threshhold of what a 25LA can easilly handle. BTW - unlike some here, I don't consider the 25LA to be as effective as a well broken in and good running Fox 35. That's a subjective call on my part - and it is based solely on feel. I have no dyno to test engines with, so it is probably a moot point to debate. Opinions are like backsides - we all have one.

I fully realize that most Brit flyers have far more experience with flying in the wind than us Yanks - that is just the reality of your weather patterns. So, you may find the 25LA fully sufficient for your needs. Me personally - I like to have the thrust to claw through the wind if necessary.

So, try both...

V/r

I suspect that the 25FP has more poop than the LA version from what I have seen. My 25FP flew a 47oz twister with not much trouble at all. The problem I had that drove me to the 40fp was one of balance. The f-twister, like Gary's, was tail heavy with the small engine and req'd tank. (the 25FP will do a pattern on three oz). I had to add 4 oz of lead to the nose to get the plane in balance. The finish was heavy and the tail group was extended a full three inches.

When I added the 40 fp, I replaced the original elevator with a specially fabricated 4 lb balsa piece with a CF joiner, clear finish, and CF horn.

I was able to remove the balance nose weight and the plane now flies extremely well--even out to 64' lines.

Gary's plane, regardless of the finish chosen, will get more tail heavy when finished. And that is a weight-costly problem because of the difference in moment arms.

FWIW

Bob and Curt - Thanks for your input. This really brings home to me the value of this forum. Looks like I may be in luck, as it happens it is a 25 FP I have in stock, so it looks as if it's at least worth giving it a try. Thinks - have I hijacked somebody else's topic? Sorry Gary!

What is NVA? I have seen this many times before and I have no idea what it is.

I have an OS 25FX. From what I can tell this is the ball bearing version of the 25FP. How do you think this will work on the F-Twister?

I had the 25FX engine on my Flite Streak. I tried it on my Ringmaster too. I can tell it has more power than the 25LA. Its a toss up when compairing it to the Fox 36X its hard to tell which one is best the Fox 36X is heaver but the 25FX will do everything the Fox will.

I tried a Fox 35 on my stock Sig Twister. I remember it flew and seemed under powered but that was a long time ago I don't remember anything else. I had an OS 40LA on the same airplane and it was too much engine but flew great until I ripped both wings off at 75 mph.

I don't want to over power this new airplane with too much engine and too much weight.

"What is NVA?"

Gary,
NVA stands for Needle Valve Assembly.
DennisV

>I tried a Fox 35 on my stock Sig Twister. I remember it
>flew and seemed under powered but that was a long time ago I
>don't remember anything else. I had an OS 40LA on the same
>airplane and it was too much engine but flew great until I
>ripped both wings off at 75 mph.
>
>I don't want to over power this new airplane with too much
>engine and too much weight.
>
>Gary Weaver

Gary;

You control speed with propeller pitch. If you are running a 10-6 or 11-6 on the LA 40 and running at a two cycle, you will get lots of speed. Put an 11-4 or a 11.25 x 3.75 on it, and you will slow it way down. What you will have is a reserve of useable thrust to get you out of situations you wish you hadn't gotten yourself into.

V/r

Gary, what kind of camera/program did you use to do your pics? I was going to show you a couple I have, but the attachment is limited to 50KB. My camera/program is an Agus DC1730, PhotoImpression4. I can E-mail pictures reduced to 23KB, but if I store them in a folder they only replicate around 170KB????? I was going to show you a Modified Twister that I'm currently flying. It weighs in at 38oz. It has a 3" extended fuselage which was drilled and skinned with 64th ply. The tail feathers (drilled) and flaps were increased to 1/4". Added half ribs to the wing along with the landing gear.(i.e. Mustang) Light wheels, adjustable carbon fiber push rods, adjustable lead-outs, transparent Ultra-Kote, 4oz. Sullivan uniflow-clunk, Brodak .40 with stock muffler, 2" spinner, modified 11X4.5 APC prop and 1oz. in the wing box.
Credits: Gil Causey (Bi-liners, Baton Rouge) and Joe Bowman, Camden, AR and a few added touches by me.
You have already recieved alot of good info to lighten up your bird, maybe some of the things I did to mine could still be incorporated into your ship, especially the Ultra-Kote or Econo-Kote:

Gary, I may of figured out a way to send the pics, may have to go two times to get both, but will try.

My camera is Kodak easy share cx6200. I don't use the camera program I can't figure out how it works. I use graphic work shop.