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Old Feb 17, 2013, 10:53 PM
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Originally Posted by Adam Stang View Post
I finished mine a few days ago and was able to maiden it Thursday...I used the recommended power setup and balanced it to spec. It was a little bugger...tail heavy and underpowered...so I went home and added 2 ounces to the motorbox and went from a 12-6 prop to a 12-8 apc...this took me from 360 watts at 32 amps to 450 watts at 37.5 amps. (e flite 480 and castle ice 50 amp speed control...and yes...you can push the 480 to 40 amps with good cooling-which this plane has) I took it back out Friday and it flew much better...but still just a bit tail heavy and a bit underpowered. I have added a half an once to the cowling and I intend to try a 12-9 prop. My Christen Eagle weighs in at 49.7 oz. with the added ballast and a 2200 3 cell ready to fly.
Adam...I am using a power 10 with a 10X7 prop for some speed, I haven't maidened mine yet due to the weather, but I did check the recommened CG with 75mm from the leading edge and the 2200 all the way forward and it seems fairly neutral because the power 10 is 1.2oz's heavier then the park 480 and the nanotech 2200 65C is also 1oz heavier then the 25C I normally use.

I also didn't balance as per the instructions....by placing the balance marks on the top side of the top wing then turing the CE upside down and trying to balance it.
I placed the 75mm marks on the bottom of the top wing and balanced it right side up on my Great Planes CG balancer with the 2200 all the way forward.

I was wondering at your prop selection..why a 12" diameter for a motor that is rated for a 9" to 10" ??
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Old Feb 19, 2013, 11:26 AM
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Cobra,

The 480 is rated for a 10 to 12 prop. I chose the 12 to get enough power. This plane needs 450-500 watts to fly properly. I could not get in the right watt range with a 10 or 11. Most manufacturers highly underrate their motors and list worst case scenario specs (motor in tight closed space with no cooling at all). The little Christen Eagle has great cooling with the large openings on both sides of the cowling. With enough cooling, the 480 can be pushed to 43-45 amps. I mentioned that I liked your motor choice before as you will be easily in the 500 watt range with a power 10 with the right prop selection (I ended up with a 12-10 prop/510 watts at 44 amps). As for the balance, I totally understand why you would balance the plane right side up as I have done this as well with other biplanes. I found out the hard way that there is a reason the manufacturer recommends turning this plane over and balancing it up side down. I balanced it right side up and ended up with a plane that was very tail heavy. I'm a decent stick and have experience with squirrely airplanes. I ended up with a tiny ground loop upon landing on my first flight. It could have been much worse. I recommend balancing the plane as the manufacturer suggests as when I did this I could easily see my plane was tail heavy. I would use a Great Planes CG machine or an equivalent and balance the plane 69 mm from the leading edge of the top wing with the plane up side down. On your maiden, if you're a little nose heavy, you will be fine. You can remove weight later as you wish. If you try your maiden tail heavy, there may not be a second flight. Good luck with your maiden and I hope this information helps.
Adam
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Old Feb 19, 2013, 06:13 PM
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Adam.....I was definately wrong about the prop, I don't know where I got 9" to 10"....
My thinking was to go with less of an amp draw and more speed and possibly flight time with the smaller prop, but I guess I have to ask how did you determine that the Christen Eagle needs 450-500 watts to fly properly, as they only spec a 10X5 with a 480.


I know my other biplane (e-flite 20-300 ultimate) is in that watt range, with a power 10 and a 12X6....althouh it's lighter and that's just what e-flite recommended so I used it.
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Old Feb 19, 2013, 11:06 PM
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Hey Cobra,
Sometimes bud...I don't know where they get these specs from...lol. There is no way this thing will fly well with a 10-6...well...maybe with a 1800 kv motor.I came up with my specs for this plane by flying and testing...I started with a 12-6 prop, at 360 watts, 32 amps...way underpowered...went to a 12-8, got 450watts at 37.5 amps...much better, it would be ok with 450 watts but it takes a downhill run into some maneuvers...for instance a nice loop is really lazy at the top...some of that is the fact that it was still just a little tail heavy at the time and I had to make lots of corrections to keep it from falling out of it, but still needs just a bit more punch...so...now I run a 12-10 prop, I get 510 watts at 44 amps...this...with the plane finally balanced perfectly should be the ticket...in my opinion. I understand the want for less amp draw and longer flight times...and if the desire is touch and gos and just watching a beautiful plane fly...then certainly 500 watts is not needed. For me...this is a scale example of a plane I saw at airshows as a kid...a Christen Eagle...and I want mine to fly like one...I'll take 5 min of ripping up the sky like the planes I saw as a child over 10 min of struggling to complete maneuvers any day. With your power 10 I would go to a 13 prop...experiment a little with your watt meter and try to get to 500 or 550 watts...just see what works for you. Fly it balanced right...maybe even a bit nose heavy and with plenty of power...you can back off both later as you see fit. I want everybody to have success in the hobby and I'm trying to help guide you to as successful a maiden as possible based on my experience...and mistakes with this plane. I promise you bud...if you fly this plane at 75mm balanced right side up...and with less than 450 watts of power...you're gonna have your hands full. Hope this helps,
Adam
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Old Feb 20, 2013, 09:38 AM
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Adam...I appreciate your comments and hands on testing is invaluable info....and I will definately test the larger props.

With your setups do you test rpms to have some sort of reference of pitch speed between different props ???
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Old Feb 20, 2013, 04:49 PM
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Originally Posted by LICobra View Post
Adam...I appreciate your comments and hands on testing is invaluable info....and I will definately test the larger props.

With your setups do you test rpms to have some sort of reference of pitch speed between different props ???
Cobra...I don't have an rpm meter. I thought about getting one just to satisfy my curiosity, but since I fly electric only my watt meter will do the trick. I have a "watts up" watt meter made by rc electronics usa...I think Tower hobbies sells it. It gives me volts, amps, and watts. With this info I can set up my planes any way I want...as long as I stay within the amp range my speed control and motor can handle I can tailor it towards more flight time (less amp draw) or horsepower (watts). Since the KV rating of a motor is rpms per volt...I can figure out my total rpms...as the motor will turn its KV rating with any prop it is rated to handle...doesn't matter if its a 10 or a 12...my 1020 kv 480 is going to turn 1020 rpms per volt...so with a 12.6 volt 3 cell I'm going to get 12,852 rpms...no matter what the prop...it wont spin a 10 any faster than it will spin a 12...that's why the bigger the prop or the more pitch=horsepower. Heck, the motor wont spin faster than its kv rating with no prop at all. The only thing you have to watch out for is if you put a prop on that is bigger than what the motor or speed control is rated to handle. You could put a 15 on a 480 and it and the speed control will do everything they can to get that prop to the kv rating of the motor...including burning themselves up. A good watt meter tells you everything you need to know other than cooling...which you have to figure out on a model by model basis...obviously the more cooling you have the harder you can push it. A good watt meter that gives all this info is around 30 bucks...
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Old Feb 21, 2013, 08:23 AM
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Blessed with decent weather today so gonna fly the CE...I'll let you guys know how 500 watts and another half once in the nose works out...
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Old Feb 22, 2013, 08:50 AM
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Blessed with decent weather today so gonna fly the CE...I'll let you guys know how 500 watts and another half once in the nose works out...
No report back....
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Old Feb 22, 2013, 01:16 PM
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No report back....
LOL Ok fellas here goes,
My buddy Kevin and I went yesterday-Kevin is a wiz with electrics and explained ohms law to me when I got started in the hobby...the guy taught me everything I know about setting up electrics...and I continue to learn. I was glad he came with me because Kevin is also a good stick and I wanted his impressions of the CE. We both flew it and we both agreed that 500 watts is enough but shes STILL a bit tail heavy. Also...Kevin had another concern...he mentioned that although we had enough horsepower we are at the edge of the motors capability to get it and that there is a need to be at or near full throttle most of the time...so the flight time is much shorter than if we could throttle way back between maneuvers. So he suggested something that would be useful and kill two birds with one stone...fly her on 4s. Its an awesome idea...heres why: My Turnigy 2200 4s batteries weigh exactly 2oz more than my 2200 3s...so theres my extra weight in the nose...I may even be able to remove some of the lead ballast later. The really big plus is easy horsepower...with an 11-5.5 apc prop on 4s I am getting 609 watts at 39.5 amps! So that's 100 more watts with 4 amps less draw at full throttle! Now I truly have CE vertical performance plus I can make enough watts at half to 60% throttle to comfortably fly around and really increase my flight times. And theres more...since the motor is spinning faster but not working harder on 4s I don't need so much pitch in my prop...it will maintain its speed AND pick up low end performance (climb rate)!! 4s is a no brainer...its a win-win in every aspect of performance. I know all this is a lot to grasp...what's needed being so far removed from what the manufacture recommends...but this happens all the time...don't get me wrong...companies like Horizon usually nail it when its a brand that their product developers are in charge of like Eflite or Hanger 9...but Seagull is its own entity and they have primarily been a nitro or gas plane company...electrics are fairly new to them...and the science and development of an electric is very different than a gas plane. This is still a great model but as in many cases the early numbers are simply not right. There are threads all over rcgroups where when people get experience with a particular plane this becomes obvious. This is not the first plane that will need "tweaking"...and it wont be the last. Don't get discouraged...this is a stunningly beautiful airplane and it flew good yesterday...it will be so much better though with 4s power. Take a little extra time to set her up right...and she wont disappoint!
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Old Feb 22, 2013, 04:57 PM
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Adam...That was a great report....much appreciated.

Unfortunately the only 4S lipos I have are 3000's and 3200's for my e-flite super cub. I was really counting on using my 2200 3S 65C Nanotechs that I also use in my E-flite Ultimate and modified PZ P-51.
I guess I'll have to run some numbers on ecalc to see if the power 10 can muster up more watts on 3S with the right prop....if not, it looks like I'll need some new lipos.

Could it be possible the CE needs a power 15 to easily get the 500+ watts it needs to fly with authority

Now that figures, ecalc is not working for some reason...
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Old Feb 22, 2013, 06:41 PM
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Originally Posted by LICobra View Post
Adam...That was a great report....much appreciated.

Unfortunately the only 4S lipos I have are 3000's and 3200's for my e-flite super cub. I was really counting on using my 2200 3S 65C Nanotechs that I also use in my E-flite Ultimate and modified PZ P-51.
I guess I'll have to run some numbers on ecalc to see if the power 10 can muster up more watts on 3S with the right prop....if not, it looks like I'll need some new lipos.

Could it be possible the CE needs a power 15 to easily get the 500+ watts it needs to fly with authority

Now that figures, ecalc is not working for some reason...
Cobra...I have the power 15 in my E-flite Stearman...I'm getting 405 watts at 34 amps with a 12-6 apc prop running on 3s...on 4s you could get 600 watts with the same amp draw with the right prop...but you can do this with your power 10 as well. The 15 is a lower kv motor with more torque...so lower rpms per volt but bigger prop capability. The 405 watts works for my Stearman because it has more wing area and no need for more power to fly scale...but on 4s with the right prop the power 15 can do 800 watts all day long. If it where mine I would stay with what you have. If you haven't already added lots of ballast to the front of yours...see if you can get your 3000"s to fit and then see how she balances...if they will fit you might just have the perfect solution...
she may be balanced with totally useful ballast...4s power and the added flight time of not only drawing less amps but adding milliamps. If they wont fit...turnigy 2200 4s lipos are 24 bucks from hobbyking...you can get 3 of those for the price of a power 15...besides...your power 10 will do 600 watts on 4s with the right prop (11-4) and draw around 35 to 37 amps at full throttle. You can get 500 watts on 3s but you will need useless ballast up front and your flight time will be very short. I don't mind 4 or 5 min. flight times if shes flying right, but I still need more ballast and the thought of getting her balanced right, adding 100 watts of power and increasing my flight times by simply changing batteries and a prop...count me in!!
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Old Feb 24, 2013, 05:08 PM
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Adam...this weekend we had a regional RC tarde show and I was able to pick up a 2500 4S lipo to test some props with the power 10.

The first was a 12X8 with a 2200 3S, 44 amps/470 watts
next was a 12X6 with a 2500 4S, 60 amps/900 watts...and and last was a 11X7 also on 4S, 57 amps/850 watts...as you can see tha amps are pretty high, I might try an 11X5 to bring the amps down a bit more.
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Old Feb 24, 2013, 08:55 PM
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Originally Posted by LICobra View Post
Adam...this weekend we had a regional RC tarde show and I was able to pick up a 2500 4S lipo to test some props with the power 10.

The first was a 12X8 with a 2200 3S, 44 amps/470 watts
next was a 12X6 with a 2500 4S, 60 amps/900 watts...and and last was a 11X7 also on 4S, 57 amps/850 watts...as you can see tha amps are pretty high, I might try an 11X5 to bring the amps down a bit more.
Cobra...bare in mind your 10 is a higher kv motor than my 480...by 80 rpms per volt...so 1184 rpms more than I'm getting...so you will have to prop her down.. try an 11-4...or maybe you will end up with a 10-6 or so...but the right combination is a matter of prop selection for sure...600 watts at 35 to 38 amps...let me know how it goes
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Old Mar 04, 2013, 05:53 PM
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Finally!

Ok fellas...
Went out to the field today and flew her on 4s...its finally right!! She flew better than she ever has...clue...I have no wingtips to patch! The plane is balanced perfectly with the heavier battery and the performance is awesome...she's fast, has plenty of vertical, and she tracks like an arrow. You have to bring it in a little hot on final but as you flare she slows down a good bit and is not so darn squirrely after you touch down...one word of caution...you have to grease her in with the bouncy landing gear but this is much easier to do now. I did a few things I haven't mentioned yet so here is the final list of mods:

1. I have 2 1/2 ounces of weight up front...1 1/2 on the very front of the motorbox and 1 oz. stuck to the very front of the cowling just clear of the intakes.

2. I went to an E flight 910 kv 480 my buddy had with a 11-6 apc prop on 4s. I am using Turnigy 2200 30 c 4s lipos. I position my battery so that the back of my battery is dead even with the back of the battery tray.

3. I mounted my speed control forward of the firewall on the right side of the motorbox(inside). If you put your battery on the left side of the battery tray it slides right past the speed control.

4. The hatch on this thing is heavy and of course far rear of the CG, so I cut the bottom out of it (including the pilot...he weighs 1.6 oz.) from about 1/4 in. behind the instrument panel to about 3/4 in. from the rear (just forward of the magnets) and about 1/4 in. from both sides. I also removed wood from the back of the hatch. I then covered the bottom of the hatch with black ultra-cote. It looks clean and went from 3.6 oz. to 1.7 oz. (this was important to me...easy way to remove weight from the rear to make up for all I added up front). I like pilots in my planes but I like planes that fly well better...besides... pilots can be had that only weigh a few grams (Precision Aerobatics is one place to get them).

So...the verdict is...I love this plane. Its beautiful and ultimately it fly's great. Don't let the mods scare you away from this baby...I'm so glad I went to the trouble to get it dialed. Horizon has a winner in my book, its a shame the CG and suggested power system is so far off what is really needed, but as I explained in earlier posts this is not Horizons fault...they didn't develop it and Seagull...good as they are...are more experienced with gas and nitro planes (put a nitro engine and a gas tank in this thing and it wouldn't be tail heavy or underpowered). Anyway, buy it, balance it, run 4s and have a blast!




3.
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Old Mar 04, 2013, 07:15 PM
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Nice Adam! Thanks for the great info...
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