GP 1/3 Pitts arf
 

Hi
I have read about the upper wing brackets breaking problem, I think I got the old version (they are brilliant, polish looking), so I am looking for a replacement from GP. My real question has to do with the red painted cabane struts itself ( metallic ones, holds the wing to the fuse), does anyone had problems with them (broken)? Shouldnt be better to make them doubles by ordering also another par of them?
I have a bme 50 for it.
THANK YOU FOR YOUR HELP.

RE: GP 1/3 Pitts arf
 

Like so many others I have had the breaking brackets problem. I also
had an issue with the struts, I held them up to a bright light after the holes were
drilled so I could see where they ,(holes) were in relation to the reinforcement area.
It was not very good and a new set was sent to me by GP.

Regards
Roby

RE: GP 1/3 Pitts arf
 

Hi Roby, thank you, I re-edited my post because I am talking about the painted cabane struts, the red metallic ones that holds the upper wing to the fuselage. I committed a mistake, I omitted the word "cabane". It is good to know what you said, thank you very much. I hope GP replace me the brackets, I am willing to pay for them as I am in Denmark.

RE: GP 1/3 Pitts arf
 

Hi guys, just thought I'd tell you about my Pitts. I have had it for a year now and am just now finishing it. I have never trusted ARF's to be sound and safe without a little going through. One of the things I did was to install blind nuts where strut and flying wires went. One thing I do know about wood screws is that if you put them in and take them out on a regular basis, they will weaken the wood anchors and finally work themselves out with vibration.
It was a rather easy process to install them. I am also putting an O.S. 3.20 in it for power. they say that you can put a 300 twin in it safely. So, I figured that, if you can put a .46 in a .40, then why not a 3.20 in a 300?
This required the removal of the firewall box down to the firewall bulk head. I added a large 3/8 " thick firewall plate and that set the engine up just right. It really looks nice. I was just looking for the disc with the photos on it and can't find it. I will look for it and post them if you are interested.
I made a new instrument panel, that fit, because the one that comes with it is too narrow. I have also built a seat and floor board with a stick and even monocoted the side panels in the cockpit!
One thing I would like to ask you guys is if you know of any headers for the 320. The last one I saw was in 1984. The tech's at GP can't find one any where in their liturature. I have had to fabricate my own.
Anyway, I just thought you might like to know what I am doing with my Pitts. bird.

RE: GP 1/3 Pitts arf
 

Hi bigbird3,

I think that the improvements you have made with the blind nuts is a good idea. I am just starting those steps, thank you for your input and wise recommendations.
Welcome to RCU.

Alex

RE: GP 1/3 Pitts arf
 

I had one until this pasted Sunday when it came apart in the air. top wing came right off and the rest of the plane went in hard, will I get anther one, YES, it was a great flying plane. I had the updated version.

RE: GP 1/3 Pitts arf
 

Thank you Redrata for the welcome.
Funfly, sorry to hear about the demise of your bird.
I finally went out in the shop and took some more photos of mine so I could post them. The only one I have with the wings on it is my wall paper and I don't know how to get it here from there!
I kind of wanted to explain how I put the blind nuts in so here goes.
I took an owl that I made out of a sharpened piece of wire and poked it straight up through the hole where the wood screws are supposed to go and punched a hole top or bottom side, depending on which wing it was, and that marked my point. Then I took a sharpened piece of 3/8" K&S brass tubing and bored a hole in the skin. Be careful not to interfere with the spar. Drill the prepunched hole to the size of the threaded end of the blind nut. Use a 4-40 threaded pushrod and push it through the wing and out the bored hole and screw the blind nut on and pull it though. Thread the guy wire bracket on the smooth end of the pushrod and then slide a 4-40 nut on and thread it down and pull the blind nut in. Be sure and set the bracket in its intended position so it makes the indintation in the correct place.
The bottom wing is easier on a couple of holes and can be accessed from the servo hole. Just a little crook in the wire and it will go.
When you are ready to patch the monocote, use a larger brass tubing, sharpened, and cut perfect circle patches. You will hardly see them.
It's a good idea to make a series of sharpened tubing for your shop. You sharpen them by using a #11 exacto and shave the inside until it is sharp. Makes a nice hole without jagged edges like a drill bit leaves. Of course the secret to the drill bit is to start is backwards for the first part and then go the right way for the rest.
I had a bit of trouble fitting the belly pan. It was about a quarter of an inch too tall. I had to uncover it and take it down. Then I had to buy a full roll of covering. I also sanded the chin air exit and covered it too. I just thought that it would look crummy flying over and be able to see wood color behind the cowl. I'm just particular that way.

I got kind of carried away with some of my detail but I figured since I didn't have to build the plane, why not put some scale detail in it. The instrument panel supplied is too narrow. I split it in half, spread it and put some more paper in the middle and shaped it from there. First, I copied it so I would have something to work with instead of tearing up the stick on. I used the instruments from the stick on for my new panel. If you screw up the instruments on the stick on, you can use the copied ones. The gloss finish will make them purdy
Using a circle template I located the proper places for the instruments on the back plate and then the same on the intended face plate. Then I cut the face plate out. Stick the instruments on the back plates and glue the face plate on and add screws. Sig sells 1/8" brass screws that are just right. I used solder for the beauty rings. Just find a dowl or something round and wrap several wraps and cut them off. Thin CA them in place and use Deft poly spray, gloss, for the finish. As you can see, it looks great!
Well, hope I haven't bored you to death but I just wanted to share this thing of beauty with you guys. bird
Well fellas, I guess you are going to have to tell me how to post these pictures. I know I saw a function the other night and now it is gone! Hurry, I'm dying to put them up.

RE: GP 1/3 Pitts arf
 

Hi Bigbird 3,
I dont know how to place pics here, I always have problems . Try at your gallery, it is easier somehow.
Question again: the red metallic cabane struts that holds the upper wing to the fuse(#14 in the kits contents), are they strong enough ???, it seems to me that they could easily break after vibration and some flights, any problem with them? Recommendations? (Im using 50 cc bme). I would like to order an extra ones to make them doubles, enlarging or making new screws holes in the new ones as needed in order to get them properly fitted over the others. What do you think?

RE: GP 1/3 Pitts arf
 

Hey Red, thanx for the reply. To answer your question about the strength of the cabane struts, I haven't flown my Pitts yet so I don't know about any problems with the structure other than what I have read in this thread. I will tell you though, I think that the struts are strong enough but the real strength comes from the flying wires. The way they are anchored and what strength the wire is, is very important. They will hold the wing on if something else fail. Within reason of course.
The struts seem to be made of a pretty strong aluminum but if you have any doubts, go to your local airport and buy some aircraft aluminum from the A&E shop and band saw out a new set. Be sure and taper the holes on both sides after you drill them this might relieve the stress cracks from developing. In fact, it probably wouldn't hurt to taper the new ones in the kit. If you do buy some new stuff, get it thicker by about 1/16".
Something I just thought of, if the screws are not completely tight at the wing end of the struts, this might offer any vibration a place to work on stress cracks not to mention the bolts themselves. It is a good idea to do a complete 'walk around' as in any full size aircraft. I know it is difficult to break down these big birds after every flying session but it must be done every few just to make sure that the radio components are still in place and that none of the structure is disintigrating. This way you will be familiar with any cracks or elongated holes that are starting to appear. I use 4-40 bolts and fiber lock nuts on my struts, inner and outer. It is a good idea to replace these fiber lock nuts perhaps every other time you break the plane down as they wear out and will loosen up just enough to let the parts move and chafe each other. As I said, this is very much like full size. The bigger the bird the more stress and scale like the material and weight. The fiber lock nuts are like the rubber bands holding on the wing of a trainer. You cut the bands off after each flying session! Never use them twice! It is cheap insurance for a long lived airplane. If you can't afford to buy a new box of bands (fiber lock nuts) that often, then you surely can't afford the plane or even to fly it. My point? What's cheaper to replace, nuts or plane? I have about 2100.00 in this one! The engine alone cost 1300.00, 400. for the plane and 425. for the radio. That doesn't even get close when you add the detail I have put into it.
Red, I hope I have put some light on your question and helped in some way.
I will try the gallery for posting my Pitts. Later, bird

RE: GP 1/3 Pitts arf
 

Hi bigbird,

I think maintenance is important, it is not precisely a day to day trainer. On the other hand, I have been reading that the flying wires are not necessary and that it takes long time at the field to have them installed. I think that the interplan wing struts will help the structure, so there is not need for a double reinforcement of the painted cabane struts. I have also checked at the galleries and other forums, and no one seems to had trouble with that or make any comment. So I guess I will be safe the way it is. Since I opened this forum, no one have made any comment. In short: No news, good news.
Thank you again, I would like to see your pics.

RE: GP 1/3 Pitts arf
 

Hi Red,
Just to touch on your comment about the wires not being necessary. Didn't you say that you have a BME 50 for it? Since you are putting such a powerful engine on this thing, as I am, I feel that you need all the insurance you can get. How much time do you have to build another one or go to a funeral because your plane broke up and hit someone?
Once you get the wires set up they will go on quickly. Faster as you go on and get familiar with the bird and it's set up. If you intend to ring it out when you fly then you need all the help you can get to hold the top wing on. Funfly RCU had his top wing come off the other day. If all you do is putter around then no flying wires will be okay but don't take a chance. Not only with the plane but what if a structure failure caused your bird to hit someone? You say 'no news is good news' how about 'better safe than sorry'?
Hope I have changed your mind Red. Don't risk the plane or someone elses safety because you are in a hurry to fly it. I have had mine for over a year and am just now getting close to flying it. After all, safety is the first rule of R/Cing. Right? Okay buddy, hope you didn't take this as a *****ing out. I would never do that but I will point out the common sence of it all if I can. Take care. Bird

RE: GP 1/3 Pitts arf
 

Hi Bigbird, I am not in a hurry(I am planning to fly it next year), but I will think about the flying wires again. People are not using it, they said that they are not functional. Take a look a the other forums. To be safe, I will write to GP. Thanks.

RE: GP 1/3 Pitts arf
 

Hi Red, good to hear you aren't in a hurry. The reason the wires aren't considered functional is because they are mounted with wood screws. If you put in blind nuts and 4-40 screws as I did, then they will be functional. We both are putting engines in that will be taking our birds to their limit. It won't take many snap rolls or tight loops to take the top wing off. I just hate to see you put all that work into your model and loose it over something as simple as flying wires.
If any of you guys want to see mine, just put your e-mail address and I will send them to you. I can't seem to post them. Bird.

RE: GP 1/3 Pitts arf
 

What happened to everybody? Hope I didn't offend anyone. It certainly wasn't my intention. bird.

RE: GP 1/3 Pitts arf
 

Redrata, the cabanes that come with the plane are fine, a guy at our field has been flying his with a Fuji 64 and no problems with the cabanes. I have a Fuji 50 in mine and no problems. Another guy in town has a 3W-75 on his and no problems just make sure ALL bolts and screws are tight. Also not one of these planes has the flying wires for the wings installed, the wood screws have NOTHING to do with being functional. They are not functional because they do not provide structural support!! The wires on the wings are for LOOKS only. The reason old bipes and mono-winged planes had wires was to support the wing NOT hold the wing to the plane incase a wing bolt broke.

RE: GP 1/3 Pitts arf
 

Thanks Navy,

Bigbird, I took another look at the instruction manual and it states that are not functional (it is written in bolt black letters, but I am the one who looks always after small little letters....). I think that Navy have a good point here. I am going to use blind nuts and 4-40 instead the original wood screws anyway, I think it is much safer the way bigbird is doing it. That means to open an observation window at the top of the upper wing to install those blind nuts and a little bigger piece of plywood over the original, just in case. I think that with that kind of modification it will be much better and I will feel more confident about flying it, even tough the model seems to be good as it is after GP took care after the original problem. Any other good idea or advice that have been not posted yet in the forums are very welcome, feel free to post them here in order to help us who are building the pitts now.
Thanks.

RE: GP 1/3 Pitts arf
 

Please forgive the retort about the flying wires but, other than the rigidity caused by the flying wires, why wouldn't they hold the wings on. I am in the big middle of restoring a full size stearman and the flying wire anchors are intigrated into the wing structure. This leads me to believe that they would hold the wing on as well as make it ridgid! This airplane is capable of 12 G's pos. and 9 G's neg. If you see how the strut anchors are built, you would question it's integrity even with the wires. The strut anchors look like a 'C' shaped shackle with bolt holes and then flash welded to the stud. Then they are screwd into the strut base. The wire anchors are bolted into the spars that are about 1X8 but substantially more with the anchor at an angle. In our case with this model, the anchors are not intigrated into the spar and the spar is not full depth as in the full size but, it will help as long as the material holds together. Besides, why take the chance? When you max the power out with the size of these birds, you start to approach a different material and power envelope than the .40 to 1.20 size planes. It becomes more and more like full size.
Think about your wing coming off for a moment. After all of the strenuous aerobatics you have done sofar. What if it did fail and shed a wing and it flew into the pit area? Who do you hope it doesn't hit? If only I had- If I hadn't- Oh I wish I had taken the time!
At that point it is too late. SAFETY IS THE FIRST RULE OF R/C! NOT PRESUMPTION! Just because it has not happened before doesn't mean it won't. Actually it has happened. Just ask Fun Fly R/C.
Hey Funfly, What did you think about in the few hours after the wing came off? I really would like for you to post those thoughts.
As I said, I'm not trying to get into a pissing contest here, but fact is fact from my prospective.
It has been said that there is no reality only perspective!. I could be all wet! bird.
P.S. I also know that the pilot could not survive a 12 pos and 9 neg but it states in the manual that the plane will not come apart in that envelope. It would probably crash in tact with the pilot blacked out or dead!
One other point, it was said that wood screws have NOTHING to do with the wires being functional. That is because if you keep putting a wood screw in and out all of the time, it will cause the wood to fail eventually because you will strip the thread holes in time and weaken them. Also, it was said that the only reason for flying wires is to support the wing. Actually, it is to also hold the wings on, otherwise they would break at the root because the structure was/is not capable of sustaining the forces, at least until they figured out how to build them so they would. Even then, there were still flying wires on the biplanes. The 'I' struts lock the wing together and they flex together but the flying wires keep them from flexing so they don't break.
Question- Did anyone see how well these Pitts were built? Do you think they built them like you would have? Safety or Presumption? Which one will you gamble someone elses life on?
Again, I'm not 'shooting' at anyone, I'm just trying to make a safety point. I have been in the modeling field for nearly forty years and I'm not tooting my horn because many of you have been in much longer but forty ain't nothin' to snort at!

RE: GP 1/3 Pitts arf
 

BigBird3: Thanks for the photos. I put the open cowl on my puter wallpaper!
Can't wait to hear how it preforms.
Very nice shop you have also.
Dennis

RE: GP 1/3 Pitts arf
 

Thanx buddy, just posted on giant scale back to you.
mighty impressive plane. I sure have my eye on the super stearman. I am helping a friend rebuild a full size at the airport. Just like building a BIG model airplane! I'll gather up a few more pix you might like. I may also have a video stream of it flying. Let you know. bird.

RE: GP 1/3 Pitts arf
 

Red, The easiest way to tell if you've got a version that needs attention is the builders manual. Look on the cover and see if it's version 1.0 or version 1.1. Tech updates are on the GP website.

Hi all, This seems to be a little friendlier thread for the Pitts than others I've seen so I thought I'd give my 2 cents worth.

I'm on my 2nd GP 1/3rd Pitts. The 1st was wrapped around an 8" steel vent pipe at our field (I wasn't flying it). The top wing was twisted about 45 degrees but the cabanes didn't break and the hardware didn't pull out of the wing or fuselage. This is where correctly hardening the threaded holes pays off. Since the wood screws aren't removed ever, I just check them for tightness before assembly on each flight. The cabanes are made of a ductile steel that'll resist breaking due to vibration. It sure proved that in the wreck. They were twisted unbelievably. That's also the problem with the original little metal brackets. They were much harder steel. The later, heavier ones are fine. If Hobbico won't upgrade the brackets for free, Tower Hobbies has the set listed in the accessories for the Pitts.

The "fishing tackle" clamps for the flying wires isn't the issue. Well sort-a. One, if really put under a load, they'd slip. Secondly, the skinny cheap wire would break in the threaded coupler. I had a nose over and cracked the leading edge of the fin. I made structural wires for the tail from some 2-56 rod, silver soldered into clevis's and used the same brackets. If these had been installed, the load would have been transferred through-out the tail and I'm sure the fin wouldn't have been stressed to crack.

There are 2 different kinds of "flying wires". There are "flying wires" and there are "landing wires". Flying wires (attached at the tip of the top wing) help absorb lift and gust loads. Landing wires (attached at the tip of the lower wing) do as the name implies. They absorb loads to the spar during landing and ground manuvering. On this model, they're just for decoration. I've made a set using an old Nick Ziroli trick by epoxying silver plastic lacing into clevis's. Since there's no way to put two of them on the little brackets, I'm making a small bar (4 total) to bolt to the brackets and that will have a pair of holes for 2 clevis's. They look much better too.

My last comment concerns wings leaving planes. If you over power any plane then over stress it, something's going to fail. This is beyond a safety issue. This is a bigger is not always better issue. Marginal workmanship, big engines, and flying a model beyond it's design is the recipe for disaster. Would you pull 12 G's in your full size Pitts just because it's designed to that limit? I doubt it.

I'm not trying to shoot anyone down here. I've also read all the threads about this model and cringe at what some guys are doing to them and then they complain when they tear 'em up. It's a good model. Treat it right and it'll be around for a good long time.

OS 300 twin
RAM twin glow driver
Slimline "Showtime" smoke pump
TNT gear.
17 pounds 3 ounces (without fuel or smoke oil)

RE: GP 1/3 Pitts arf
 

Amen Dave,

We can 'what if' anything we do to the point where we might as well not do anything. The GP Bipes were designed to be flown without flying wires, the wings are structurally strong enough to support flight and aerobatics. Yes if they are over stressed they are going to fold-up just like a full size bipe would if you exceed its G-limit. Whether you have wood screws or bolts, the flying wires on these ARF's is not going to hold the wing to the plane.

http://www.airbum.com/articles/Flyingwires.html
http://www.centennialofflight.gov/es...ane/Tech13.htm
http://www.thosemagnificentmen.co.uk/glossary.html

RE: GP 1/3 Pitts arf
 

Navy, I rest my case.

I'd like to hear from others (who have one of these) what special equipment they've installed and how it's working. I've seen a few of these well over the 20 pound mark that still fly very well.

I've gone to Sky-Lite 5" tires (I've yet to modify the wheelpants for these bigger tires) with the TNT gear which is 2" wider and 2" taller. This combination sure seems to take out the "biplane dance" during landing on our less than perfect grass field. It also gives the plane a more scale stance. No I wasn't after scale looks, just a more managble beast!

RE: GP 1/3 Pitts arf
 

Hi Dave,

Here are a few photos of my GP Pitts. It has an OS 300 Super Gemini twin, Slimline Pitts muffler, Slimline Ultra Fueler, Charlie Hillard graphics, 7 Futaba digital servos, Futaba Matchbox for the 4 aileron servos, 2 6v Ni-Mh battery packs, MPI Onboard Glow Driver, Du-Bro inflatable tires and all flying wires installed. I have never had a flying wire break and this bipe always draws attention wherever it goes. The sound coming from the engine through the Slimline muffler is awsome and many say it sounds like the full size flying around. The engine is very smooth running, which may account for the flying wires staying put. The OS 300 supplies more than enough power for my Pitts and I truly love flying it.
By the way, this Pitts received the "Pilot's Choice Award" given at our club's Spring Fling Scale Fly-In this spring.

RE: GP 1/3 Pitts arf
 

Hi
Dave: I have the 1.1 version but I did replace the cabane and upper wing wood screws for 3mm bolts with blind nuts. I finished today the reinforcement of the firewall area, opening a hatch at the angled wood between the LG and the firewall. The job was a piece of cake that way. I have also new brackets that GP sent me really fast here (Denmark) and at not cost. These new brackets are dull metallic color, different to the bright metallic color I had originally. Good to heard about the red metallic cabanes that hold the upper wing to the fuse, I had a Midwest Super Stinker and one of them broke sometime ago, but nothing happened.
I am a "four stroke man". I really like those beautiful twins in your pitts (rcjacket included). What a great combo!. I decided to use gas. Let me tell you that my bme 50 cc has a very nice sound at idle (my second gasser). It idles very nice at 1200 rpms, but of course it will never match your 4 stroke twin sound. Well, I am quite happy anyway.
Did you reinforce the LG area? This would be my next step, but not so sure if it is necessary, looks good the way it is.
Also my upper wing incidence seems that is going to be 1 negative, I think I am going to leave it like this, I have another bipes and it works good that way. My bipes flies better, I think. ( not an expert just an opinion)
Bigbird, I am going to send you my mail I would like to see a picture of your pitts, sounds really nice.
Thank you. I am getting really nice answers/advise from you.

RE: GP 1/3 Pitts arf
 

I now have roughly 100 flights on my Pitts with a DA 50. This is my second model as well. I see a few others have had to get back in the saddle after a mishap. I won't go into the details of how I lost Pitts-I . It's too embarrassing. Pitts-II has held together very well with no signs of cabbane problems or anything else coming loose. As was previously mentioned, just make sure you check the nuts and bolts closely for tightness. I did reinforce the the firewall, which I'm sure has been a big help in keeping the firewall good and snug. Mine weighs in at roughly 17-18 lbs dry. I have a simple smoke system, which I'm very pleased with. I wish I had put a 32 oz smoke tank in and a 20 oz fuel tank. I currently have 24 oz for both. Smoke runs dry too darn fast. If you happen to have a DS at this weight it really doesn't fly well without power. Flies more like a rock, so watch trying to make a turn down wind. It's better just to get it down by keeping it stright if you can. Just be prepared for what you will do if a DS happens.

I fly mine pretty much to scale. The DA-50 is a beautiful engine for this bird. I had a few problems getting the take off roll nice and straight. It takes off a lot like a Cub, but with much more power. If you aren't ahead of the rudder and the throttle it's better to abort and do it again. Once you get the feel it tracks very nicely. Mine flies like a baby and lands fast, but no problems with bouncing if you come in a little hot. It slows quickly when you chop the throttle.

BTW, I have no flying wires on mine. Just didn't want to mess with them during field assembly. I guess you can install them so they will help to support the wing, but as the directions said, the stock wires don't provide any structural support.

Good luck with the new birds.