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Seagull Decathlon

Old 03-13-2005, 09:20 AM
  #1  
philg2005
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Default Seagull Decathlon

I have just finished building my first arf plane, a seagull decathlon, and ive noticed a few features that could be improved. First, the wheels are too small, i have switched the front wheels to much larger, rubber ones, but the rudder wheel is tiny, and has already snapped off whilst taxing! Does anyone have a design for a homemade rudder wheel assembly, as i have the two spare smaller wheels that came with the kit.
Also, the wheel axles keep getting loose when taxing ( i took the wheel spats off as i think they would be in the way for the first few landings), but would a bit of glue on the bolt prevent the wheels from falling off due to vibrations?

Any tips would be apreciated as i am new to rc flying.

Thanks
Old 03-13-2005, 11:29 AM
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IronCross
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Default RE: Seagull Decathlon

I found the tail wheel unit with the plane useless... Even if you get it to work the wire the wheel goes on is too soft and keeps bending.. I replaced the unit with a sullivan tail wheel unit with a 1" wheel... Works great... I also put in bigger wheels on the mains.. As for the wheels falling off ?.. I used Dubro axels and wheel collars on mine... No problems there.. On the wheel "spats", I glued a stip of 1/8 inch hardwood to the inside of the wheel pants. Then I slotted the bottom of the "spat" so it slipps over the axel snugly. Then used a small bolt and Tnut to attach the wheel pants to the landing gear.. You can tighten the axel up real good that way and the wheel pants (spats) go on and off real easy...
One other thing... The peice of hardwood in the fusalage with the two T nuts in it that the rear of the wing bolts to is apparently weak and the plastic T nuts are useless... I knocked out the plastic T nuts, epoxied a second piece of hardwood to the bottom
of the existing one. redrilled the two bolt holes and installed metal T nuts... Seems tp be holding well...
Hope that helps...
Old 03-13-2005, 12:02 PM
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forestroke
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Default RE: Seagull Decathlon

phil - i was afraid you'd be new to rc flying. this is not the plane to start out on. trust me, you don't want to try this plane as a first plane because it is not a beginner's plane. after all the advice, the best piece of it is to get a real trainer. it may not look as good but it will definitely last longer. you can learn how to fly first then come back and fly this plane as a second or third plane. i'm sure a dozen people will chime in to tell you that learning on this plane would be like trying to learn skiing starting from the black diamonds (most difficult slopes). in otherwords, you'll get down quickly and most likely not in one piece!
Old 03-13-2005, 12:12 PM
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IronCross
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Default RE: Seagull Decathlon

What fourstrke said...
I have three differenct Decathlons and this is the hardest of them all to fly... It handles more like a cub then a Decathlon... Mine is really squirlly on the ground... In the air it needs flying, not really all that relaxing to fly... In all fairness I am still playing with my CG and expos etc... Hopefully a lot of this can be adjusted out... Not a bigginers plane....
Old 03-26-2005, 06:48 PM
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c130j
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Default RE: Seagull Decathlon

I have about seven flights on my decathlon and the aircraft is real touchy in the air. I set the CG at 3 1/4 of an inch back from the leading edge with the fuel tank empty. The elevator and rudder are very sensitive almost like the aircraft is tail heavy. Has anyone found a good CG setting for this aircraft?
Old 03-26-2005, 10:35 PM
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Default RE: Seagull Decathlon

I set mine at 3 1/4 also and have since added 3/4 oz to the firewall... That and I have cut back on the throws and added 30 percent expo to the elevator and ailerons.. It is becomming much tamer and fun to fly.. I also have been having good luck holding a little up elevator on take off which has improved things considerably.. Just a matter of getting things worked out I guess. It a nice plane, worth working with IMHO.
]
Old 03-27-2005, 07:36 AM
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c130j
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Default RE: Seagull Decathlon

thanks iron cross, I also decreased the throws on the elevator and rudder. I would be curious if you have the time to check your balance with the 3/4 of a ounce to see where in inches it balances. I have been flying it with a super Tiger 51. I have been playing with a few different props and it seems like the engine likes larger diameter with less pitch. Probably due to its a little on heavy side. thanks again
Old 03-27-2005, 10:25 AM
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IronCross
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Default RE: Seagull Decathlon

Next time I get the wings on it I will see if I can get that for you.. I have a Mag .70 4s in mine with a 13x6 APC . I can fly it around half throttle just fine.. However when I go to full throttle the engine speeds up but nothing seems to change with the plane... Apparently there is a lot of drag with this pland.. I am thinking of trying a 14x4 as soon as I get a couple of gallons of fuel through the engine.. On take off I have started adding a little up elevator for control and it has prematurly jumped in the air a couple of times and momentarily just seems to hang there... The 70 seems to have enough power however to pull it out.. Usually on take off I like to advance the throttle as quickly as possible to get the tail off the ground for steering... That doesn't seem to work with this plane.. It just torques to the left off the runway... As I tweak this plane out and "we" get use to each other I am enjoying it more and more...
Got any pictures ?
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Old 03-28-2005, 10:10 AM
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john neilson
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Default RE: Seagull Decathlon

Well fellows, put your tail between your legs and install a GYRO on the rudder! There is no sense in fighting all the possible combos of rudder to elevator to throttle. I have mine plugged into the retract switch and as soon as airborne and about to turn, switch it off. On final, switch it on for centerline landings. It is a very small investment to have more enjoyable flying with this very sensitive plane. I prefer a tad nose heavy which is easy to control with trim. If pride is in your way, don't tell anyone you have one installed!

JOHN
Old 03-28-2005, 10:23 AM
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IronCross
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Default RE: Seagull Decathlon

What kind of gyro are you using John ?... Might not be a bad idea
Sure could not let the word get out at the club though.. []
Old 03-28-2005, 11:26 AM
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john neilson
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Default RE: Seagull Decathlon

I have an older Futaba installed, discontinued. Just checked Tower and they have one for $120. I use JR but just clipped the alignment sleve off and it works. As far as your club buddies, I went through some harrasment from mine. A funny story...after about three sessions of fighting it on the ground I installed mine without telling anyone. On the next outing, typical bantering, " you gonna get it right this time"! So I offered one buddie, Scale Masters type guy, the challenge of getting her down the centerline. After two aborts he got going off to the left, typical torgue. Refuled and I of course said I'm ready to try her again. Switch on she went sraight down the centerline with very little input to rudder.
Landed and off again to their amazment. I had the hardest time keeping a straight face and they all said I must of been praticing. This same guy was beside himself and asked to try again! Ok, and turned the switch off and a repeat performance. He gave up and I took over, switch on and perfect take off. He was talking to himself while I was getting all this praise. Not until the end of the day did I let any of them (10 guys) know what was going on. It turned out to be the funniest thing that has ever happened within our club and they are still asking this guy when he is going to get a GYRO!

Just buy one!

JOHN
Old 03-28-2005, 11:50 AM
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IronCross
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Default RE: Seagull Decathlon

Great story John... Like to have seen that Kind of had the same experiance.. First couple of take offs were realy ugly.. Got it in the air but the aiplane gods were with me that day.. Well everyone is giving me the what for's, "you need to go back on the trainer cord" etc. So I got our club "expert" to show mr how it should be done... His/there theory is pour the coals to it to get the tail off the ground to steer it... Well he did that and the plane made a 90 degree left turn into the grass and flipped over... Foutunatly there was
no damage and it did setteled them down a little Last few takeoffs have been a lot better.. I am holding a little up elevator in it until I "gradualy" get the speed up. Makes steering it a whole lot easier.. Now if I can only remember to release the up elevator at the right time...
Old 03-28-2005, 12:22 PM
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john neilson
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Default RE: Seagull Decathlon

I start off with about a third to half throttle depending on a headwind and when the tail is flying, gradully ease in full. She requires very little elevator to make a nice lift off and as I said before, I then turn the gyro off. If you don't it will fight and skid while turning. You should use rudder and alieron for coodinated turns with this plane. I have fun doing flat turns with opposite inputs. Looks very scale. In all honesty, I would not of bought this plane because of having them before. I believe they were called Easy Arfs. A foam type backed covering. Anyhow, they were horrible but when I saw the Quality of these Seagull models, I had to have one and accept the challenge again.

Invest in a GYRO and start enjoying it even more.

JOHN
Old 03-28-2005, 01:50 PM
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IronCross
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Default RE: Seagull Decathlon

I know what you mean by coordinated turns... The first flight on my first bank for a turn the tail was hanging way down... At first I thought I had really screwed up the CG but then it dawned on me that I need to make coordinated turns... I did however take out about an 1/8 inch down aileron on each side and that improved things greatly.. As soon as the weather straights out and I can get some steady flying in I want to work on those flat turns too..
Old 04-02-2005, 08:15 AM
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forestroke
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Default RE: Seagull Decathlon

Gyros have been used in twins for a while to compensate for an engine out situation. You can find some good information in the twins forums. They have been known to give the pilot just a few seconds of controllability right after a flame out so that the plane doesn't enter into a spin and crash. This, however, is the first time I've heard of someone using it on a single engine plane. Can't say that it's not a bright idea!
Old 04-05-2005, 05:48 PM
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c130j
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Default RE: Seagull Decathlon

Iron cross have you had time to find where your CG is with the weight you added to the nose?
Old 04-05-2005, 07:52 PM
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Default RE: Seagull Decathlon

I am sad to say the plane was rekitted yesterday.. I was taking off, there was a left to right cross wind (5 to 10 mph), the plane went airborne, made a 90 degree right turn and flew into a fence.. It tore the wings off along with the cabin part of the fusalage.. Pretty well totaled it.. I had no control over the plane when it did that.. Everything checked out fine (except for the plane) afterwards... Possiblity it went into fail safe but who knows... Neither I nor anyone who saw it can really explain it.. Prevailing theroy at the moment is the plane left the runway before it had enough airspeed for the controls to function and the light croswind took it from there..
Old 04-05-2005, 08:42 PM
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Default RE: Seagull Decathlon

Aww geez IC, sorry to hear that
Old 04-05-2005, 09:59 PM
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Default RE: Seagull Decathlon

Thanks MF... I plan to order another one in the morning... After some deep thought on it I am pretty sure it was my fault... I was holding a little up elevator on it to track straight, I released the positive elevator and the plane started turning to the right... I poured the coals to it to try and get the tail off the ground to stear it and it went airborne and into the fence before I had enough speed to fly it... Just a bad decision on my part...
Old 04-06-2005, 12:46 AM
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Default RE: Seagull Decathlon

Well guys, when are you going to pay attention? Iron Cross and all others on this thread, I have told you, invest in a GYRO!. The Decathalon will bite you eventually. The airplane does not know there is a cross wind, the pilot does, and so does the GYRO! Now IC, you are going to buy another one for $150 bucks but not spend another $100 or so to protect your investment? Think about it, your time, your pride, your loss! Or, are you too proud to say," this plane needs a GYRO to be flown"? You are not sitting in the seat so that you have that seat of the pants feel for what it is doing. We all make the mistake of not being ahead of the airplane at takeoff or during flight or landing, for that reason alone. Think about it and put your tail between your legs!

JOHN
Old 04-06-2005, 01:11 AM
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Default RE: Seagull Decathlon

Iron Cross, I'm sorry to hear about the crash, this is the worst part of this hobby-sport. The description of the wind conditions leads me to believe that you still had rudder authority, and that something other than the cross-wind led to the turn to the right.

I am very interested in the gyro application to the rudder, as suggested by John Nielson. It just might solve a lot of problems specially with the WW2 fighter planes.

I don't believe YET that the Decathon is uncontrolable on the ground without a gyro, but it might be just the right plane to test a rudder gyro on, while someone is in training to fly some WW2 fighter planes. That would be us, my youngest son and I. We have a Hangar 9 Corsair, and a Seagull Zero, all ready to go. The Corsair has had 4 flights, the Zero has zero.

We are just emerging from winter here, only a few flyable days since before Christmas, everyone has cabin fever with their new planes.

Regards from old bird.
Old 04-06-2005, 09:41 AM
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IronCross
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Default RE: Seagull Decathlon

John
You are right [sm=crying.gif]. My next one will have a gyro. Biggest problem is finding a reasonably priced one that will do the job...
This plane is a lot tougher then I thought.. The firewall/fuslage are still in one peice.. The wing rippred off takeing the center portion of the fusalge to below the side window and the windshield etc with it.. Busted the plastic spinner off it, ripped the landing gear out etc but the fusalage did not fold and the firewall held.. I was impressed.. Probably would not have been even that bad but I had the wing bolt mount really beefed up.. It held but took the side of the fusalge with it... Nylon wing bolts held well too...

Old bird
On the ground once I released the up elevator the rudder was useless.. It alsmost seems like by the time it gets enough speed to be effective it goes airborne.. Till then your all over the runway unless you hold up elevator.. Once airborne I did not try the rudder unfortunatly.. I was trying to bank it but to no avail...
I have tried adding expo and removing expo on the rudder.. Have toed the wheels in which made things much worse.. Seems if one wing lifts before the other the wheel on the ground starts steering the plane off the runway.. I set them back parallel and that seemed to work best.. Consensus of the "experts" at the field seems to be that the short moment of the fusalage is the reason for this...

I like this plane.. The next one will be even better. With John's gyro of course
Old 04-06-2005, 12:16 PM
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Default RE: Seagull Decathlon

A picture of the results []
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Old 04-06-2005, 12:20 PM
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john neilson
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Default RE: Seagull Decathlon

Thanks IC & Old Bird for acknowledging my input. Too bad about your loss IC but without offending you, I hope, " I told you so". This plane, as you mentioned, is short coupled as are allot of the scale tail draggers and WWII era planes. You will experience much more satisfaction when you succumb to a gyro. I have been flying RC since 1967 and this is a first for me and I can assure you, there will not be another witout one! My 81" J3 Cub is about to recieve one even though they are not as bad as the Decathlon and I can't wait to see it run down that centerline.

Best of luck guys and keep me posted,

JOHN
Old 04-06-2005, 12:24 PM
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Default RE: Seagull Decathlon

And another[&o]
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