Just posted a video of GP Super Stearman with Saito 170R doing a taxi test on RC Universe. I will be taking the plane to the club for its Maiden Flight in the next few days (Weather permitting).

I had my Maiden flight yesterday. I thought “my” plane would be magically immune to the “positive wing incidence issue”. Wrong! She lifted off and climbed faster than expected. I managed to push the nose down before it stalled and get things under control. Full down trim on my controller and the rest of the 12 minute flight was uneventful. The landing went fine. I’ll post a video of the last bit of my flight and the landing later tonight on RC Univ.
My plane is balanced at 5.5 inches as stated in the manual. I have not measured the incidence of either wing yet but I will now. I’ll do what I can to adjust the lower wing to 0 if this is required, as I suspect it is. As far as I can see, the only way to do this is to shave a little off each side of the fuse where the top of the lower wing meets so the back of the wing can sit deeper in the fuse to lower the angle. Has anyone done this? Any tips?? If the wing top is out, a few washers should do the trick. No problem there. I may also play with the C.G and bring it a little forward.
The Saito 170 seems O.K. power wise etc. I am running it fairly rich as it is new. I will try a 16 X 6 prop to compare it to my current 16 X 8. The other plane I am flying right now is a twist 150 with a Saito 180 in it. Definitely different birds. I’ll post again after I make the changes.

Before you go and start changing the wing saddle, try adding a little nose weight first. Sometimes it is easier to put a bandaid on the problem than going straight to the knife.

Thanks for the advice. I agree. Changing the saddle would be quite an operation. I will fly it again with a CG change first. I'll get a chance tomorrow to measure the incidence as well and just see how bad (if at all) it is.

mrcasey69,
I had the same exact problem. This is what I found. If they would have said check the incidence when putting on the upper wing we wouldn’t have this problem. I talked to a guy that used an incidence meter to install the upper wing. He said he push the center of the wing down and adjusted the small brackets at the ends until he zeroed the upper to the lower wing.
Stand to the side of the plane. Look at the lower and uppers wings you will probably see it, the upper is positive.
My lower wing and the horizontal stab are zero to each other. The upper wing was 4 ½ positive. I made some round wood shims with a hole in the center about 5/16 thick. I put them to the rear of the upper wing were the screws go in and used longer screws. If you put them right under the upper wing and paint them white you won’t even notice them. I also moved the CG a little forward. If flies great now.
You don’t have to cut or sand the saddle.
I hope this helps.
Shubova
[8D]

Thanks Shubova. I WILL be looking at the wings a little closer tomorrow. I also picked up an incidence meter. I will try moving the CG a little foreward and putting some shims on the rear screws where the upper wings mount. Anything is better than altering the Saddle. I'll report back. I'm probably going to fly again Saturday and/or Sunday. Check out the video.

I have the wing incidence issue also, only mine is the opposite of everyone elses, my bottom wing is out. With the stab and top wing at 0 my bottom wing is +2.5. Short of major surgery to the wing saddle there's nothing I can do about it so I'll just have to live with it. Right now I have to carry about a 1/4" of down trim.

very nice job mrcasey! use 4 aileron servos or are they slaved?.

Kvisto: Thanks, slaved servos on seperate channels for Ailerons. Hitec 5645 MG digital servos on everything. I beefed up the hardware for the clevises, rods and control horns on all flight controls.

I set the plane up on the bench and checked some things out. With the horizontal stab leveled at zero, the lower wing was at pos. 0.5 degrees, the upper wing was at neg. 0.5 degrees anf the engine thrust line was at - neg. 0.5 degrees. Needless to say I was surprised. None of this should cause too much in the way of the kind of flight characteristics I am experiencing. As far as I am concerned, the net result of that sould be pretty good. I am now suspecting that my C of G is the culprit. I did check it twice. I may have goofed up; or, perhaps, 5.5 inches from the leading edge of the top wing may not be the ideal C of G for MY plane's configuration?

I will double check my C of G and perhaps move some things around to bring it more foreward, regardless of the new measurement. I will also add a 4 washers (not too thick) to the back bolts for the top wing where it attaches. I am including a few shots from the side of the Stearman. The way it looks (in person at least) seems to confirm the readings I took tonight.

I would like you to know how happy you have made me with the selection of aircraft engine and frame. I am building the same combination but behind you a few weeks. I had just started looking at the firewall design changes needed when I was called out of town for business. Setting here in a hotel this evening decided to look for some ideas and found the excellent work you have posted. I will be sending results from my work to compare but it won't be for a couple of weeks because I have to get back from this trip. Thanks again for posting.

jimm

Jimm, thanks for the kind words. Rcten from this forum has been a good source for me in the same way. One additional tip I learned from contact with him is: Place the battery for your glow driver system in the same part of the fuse as the fuel tank. Even the 170R needs a little help to balance this plane. I am now considering moving my reciever battery to the same spot.

Just because it is an ARF does'nt mean every one of the same model will balance at the same point. Some of the may have different grades, weights of wood, the gear the builder decides to put in them etc. I don't remember the exact cg of my Stearman, but I do remember it was not quite where the instructions said it should be.

I have not started mine yet, but it would be nice know where the C. G. is on the plane after you have test flown it. I wonder if most of them are the same or not. Thanks guys for all the good information!

Capt. Ron,
As the guy said before not all ARFs are built exactly the same. Depending on things like the materials used, the engine you install and even the way you built it. The practical thing to do is set it at the recommended CG then go from there.
That being said I ended up setting the CG a little forward ¼ in. Just to be safe I would recommend setting it forward just a little to make sure you can land it, and then go from there.

On this plane I found that incidence is just as important (if not more) as the CG. Make sure you check the incidence of the Upper and Lower wings and the horizontal stab, they should all be “0” to each other.
As I mentioned in a previous post if I had known that the incidence on the Upper wing was going to be off I would have adjusted it while I built the plane. I ended up using shims to solve the problem.
In this scenario I would recommend attaching the Lower wing in the saddle, level the plane until the wing is at “0” incidence then install the horizontal stab. Set it to “0” (while gluing) then do the same to the Upper wing.

I spoke to someone who also has a GPSS he had the foresight to use an incidence meter when he installed the wings. A practice I indent to do when building my next planes. He said he had to adjust the brackets and force the Upper wing into the “0” position before attaching it with the screws but when he finished if flew with no problems.

The last thing a would like to say is; I mentioned the engine before because that could throw off the lateral balance of the plane. I always check and adjust the lateral balance. I would rather do that then to add in a lot of trim in the air to make the plane fly straight.
You may or may not already know many of the things that I said before but I hope this helps.
Good Luck,
Shubova
[8D]

PS: You have been threatening to build that thing for a while! [sm=biggrin.gif] LOL…get ’er done!
Believe me it's a great feeling when you see that baby fly! It is sweet! It gives me goose bumps just thinking about it.

I know that I am the new guy on the block but in response to your “battery locations” thought, what I have done is placed both of the 5 cell NiMh batteries (ignition and radio) on either side of the gas tank similar to what iflyfastashell posted in a photo on the 28th of September. If you place the 2.4 GHz receiver auxiliary unit somewhere else it will fit with foam just fine. Since I have not finished the engine mounting I cannot tell you how that balances, but it fits great. Also instead of placing the auxiliary receiver unit there, I placed it back and down so I could have the antennae at 90 degrees to the main and also be perpendicular as stated for “best practices” in the manual. That is what I have done, offering it to any that want to read.

jimm

I always have other things to do around the house. I have to many hobbies. The last three years I have been building a garden rail road in my front yard. I have been fixing some of my other airplanes. I just finished building the Sig King Cobra. I hope to get a good start on my Stearman real soon. I'm all so having my son making a mold of Snoopy. Snoopy and his brother will be flying the plane. I want to have Snoopy's head to turn with the rudder servo. Thanks for all the good information !!!

I also had the same issues as most others on this post, with 7-1/2 degrees of down elevator needed to trim the plane level at 2/3 throttle with a Zenoah G26 and CG at 5-1/2 inches. Using the stab as "zero" (there is no datum) I found the bottom wing was at +1/2 degree and the top at + 1-1/2 degrees. Changing the top wing to + 1/2 helped some but not enough. I ended up modifying the wing saddle to get the bottom wing to -1/2 and set the top at zero. Now the plane is much better but far from perfect. I still need about 3 degrees of down elevator and in a power off vertical dive it moderately pulls out. My next change will be to try moving the top wing to - 1/2 degree. This is about all I can get and will include drilling new holes in the cabane struts as otherwise the front holes would miss (below) the hard points in the fuse.

Modifying the wing saddle was not as hard as I thought once I figured out how. With the airplane inverted on my bench I first placed a piece of single ply (not corregated) cardboard inside of the saddle and had a helper draw a line on the cardboard following the saddle profile. I cut along the line to create a saddle-shaped template. I put the template against the inside of the saddle dropped down 0.20 inches at the rear and zero inches at the front while my helper drew a line along the template edge against the inside of the saddle on both sides. Next I used a hacksaw laid across both saddles to cut narrow vertical curfs into both saddles, simultaneously, down to these lines, switching sides frequently to judge the depth of cut when nearing the lines. I cut multiple curfs spaced about 3/4" apart along the entire length of both saddles. I purchased a 2" diameter by 1-1/2" wide drum sander at Ace hardware and chucked it into a drill that has a horizontal level built in. I used this setup to evenly remove saddle material down to the bottoms of all the curfs and to smoothe the shape from curf to curf. This is not hard because the material being removed is mostly balsa and one piece of light ply on edge. I used the template again to cut 5/8" wide pieces of MonoKote to finish the saddle edges and keep the side covering secure (Balsarite helps here to secure the MonoKote and oil-proof the saddle wood). The hacksaw was also used to cut the trailing ends of the saddle into the corners where the drum sander radius is too big. A dremmel tool helped here too.

This provided a 3/4 degree change in incidence. Such modifications should never have to be made if an ARF is well designed and well built. However, the Stearman is such a nice looking plane I felt it was worth the effort to make it fly as well as it looks.

Shubova,
Who makes a good incidence meter that will do a good job and not cost an arm and a leg? Are they hard to use? Thanks

Sorry to short stop, but I think the great planes incidence meter has been discontinued, leaving the excellent robart version out there. http://www3.towerhobbies.com/cgi-bin...ncidence+meter

Capt Ron,
I agree with kivisto, I use the Robart and it's been fine. I understand there is some ditials but I don't have any names. My RC guru likes the Robert too. He fly’s completion aerobatics and scale, and he trained me so I trust his word.

As long as you don't have a problem seeing it's great. Also if you think about it when you start you don't really have to level the plane to "0". As long as the other surfaces read the same number they all should be “0” to each other.
Now in the case were a wing is to be either positive or neg. to another surface lets say the horzi. stab. Then I guess it would be better take the time and level it to“0”.
I hope that makes since, if not read the instructions, I found them very informative. Then you can work out a procedure that you like.

Again here is the link that kivisto posted.
http://www3.towerhobbies.com/cgi-bin...ncidence+meter
Good Luck!
Shubova
[8D]

Thanks guys ! I will order one today. How do you find out what the settings should be? Are the settings basic for all planes? On the Super Stearman is everything best at "0"? I have a few planes and I would like to check everything out on them all so.

Why do you even need to check, are you have problems flying your plane out of the box or did you have trouble assembling the ARF?

R/C Foolish

The way I understand, the guys that just built the Super Stearman had problems. I never had to use one. This is my first double wing airplane. I thought maybe I should get one to make sure everything is OK. Do you have one?

I have the Robart one, I did not check my wings but my Stearman flies great, so I never had a reason to check.

R/C Foolish