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Old Feb 15, 2010, 06:32 AM
Groundlooping is an art!
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Originally Posted by Wind_of_Change View Post
Weather tomorrow looks great for February. So it's going up, and it's coming down one way or another.
Fingers crossed and good luck!

Looking forward to your flight report

Cheers,
Terje
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Old Feb 15, 2010, 09:30 AM
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thanks. i have one retract servo, so last night i just modified the opening to accept it. its tight, but it worked. and yes, my name is todd also. im going to have a lot of questions about the build on this one, as this is my first, like how do you program the start/stop points on the servos? where can i put the receiver and batt. so they arent in the way? there doesnt seem like theres any room. you know, newbie questions. ive already hit up the lhs, but none of them have even seen this one yet! but, thanks again for the info, and keep us posted on the on the maiden voyage!
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Old Feb 15, 2010, 10:28 AM
More Combat Please!
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Todd,

This thread has some good pictures from other builders on how they did their battery tray. Mine is similar. My motor is mounted to the nose of the plane instead of to a custom motor mount like others have done. Seems to work okay, but I'll let you know after it flies.

The start/stop points on the servo motion is programmed in the radio, which of course means that the programming entirely depends on which radio you're using. As with any servo, it's just a matter of setting your "throws", or range of motion on the servo arm.

UPDATE: The weather man had his head up his fanny for today. 45 degrees with Partial Clouds at 10,000 feet, and 8% chance of rain SOMEHOW BECAME 34 degrees with Clouds at Ground Level and 100% chance of snow.

I'm loaded up, and waiting for the weather to improve. I'll post as soon as I get done with the maiden... whenever that is.
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Old Feb 15, 2010, 02:16 PM
Groundlooping is an art!
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Norway
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Originally Posted by Wind_of_Change View Post
Todd,

My motor is mounted to the nose of the plane instead of to a custom motor mount like others have done. Seems to work okay, but I'll let you know after it flies.
Great to hear that you have done what I was planning to do. My "no brand" C50-55 580kv fits at the front with only minor modifications to the engine bay. Easy way around.

Did you strenghten anything, or did you mount it directly to the front ply wood plate?

Cheers,
Terje
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Old Feb 15, 2010, 03:01 PM
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mounted mine to the plywood plate. its pretty thick and worked well. i just hope i have the correct angles on the motor so the prop sits right. guess thats what shims are for if its wrong! lol.
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Old Feb 15, 2010, 07:46 PM
More Combat Please!
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Well guys, the maiden flight was fantastic. I had decided not to go because the rain never stopped, but my buddy said "I used to live in Washington, if we weren't okay flying in the rain we'd never fly". So he talked me into going up and maidening in the rain. We waited for a window when the rain lightened, it was a light drizzle really at the time of the flight, nothing too serious.

So, on to the news -

This plane flies amazing, like it's on rails. It's an absolute joy to fly!

For those of you who were worried about weight, this plane handles weight fine. My setup seemed heavy at 7 lbs., but it took off quickly, flew smooth and graceful, and landed fine. Naturally it comes in little hot with this setup, but nothing a decent pilot can't handle. I was still able to cut throttle all the way on approach and glide it in nice and easy. It flies better than my P51 by a long shot, just seemed much smoother and more solid.

The rubber wheels were a bit of an issue, they bounce like rubber balls. I think I must have bounced 4 or 5 times down the runway on landing before it stuck. Kind of funny to watch.

The rubber stoppers on the wheels act like brakes, which made me nervous at first. They caused a bit of resistance to the spin of the wheels, and I thought it would make it nose over on landing, but it didn't... in fact, I liked the resistance because it helped slow my plane down! And it didn't cause any problem taking off either, so all is good there.

I had about 4 clicks of down elevator trim (forward on the stick) when I landed, which made me think maybe it was still tail heavy, even with all that weight I stuck in the nose (giant motor, big battery), but that wasn't it.

My CG was spot on at 4" from the leading edge (at the fuse) using my 4400 mah 5S lipo.

But I don't think that it was tail-heavy. On the second flight I stuck a massive 5000 mah 6S pack in it to make it more nose heavy, and the trim didn't change much, it still needed 3 clicks of down elevator to fly straight. An extra 150 grams in the nose and almost no change, well that leads me to believe that there may be a slight incidence issue with this bird. That or the motor needs to be shimmed. My spinner sat flush with the front of the plane, so I just assumed that was the proper motor thrust angle. Maybe not.

Nothing serious though, it flew great with that little bit of trim on the elevator. It needed a click of trim on the ailerons, and then it flew rock solid.

You should see this thing HAUL BUTT with a 6S 5000 mah pack on a 13x11 prop. WOOHOOOO! The Turnigy SK 50-55 580KV motor is great on this plane, and I would highly recommend it. The motor and ESC were only barely warm after my maiden.

All was not perfect, however. I suffered yet another XPS receiver lockout on the 2nd flight and piled my gorgeous new plane into the muddy dirt field. Plane's a total loss, but all of my gear survived except the two interior servos. I'm not sure why, but both the carbonite gear heads snapped. HS475 servos, you think they'd be tougher than that.

The receiver had a ton of juice, with 2 bec's feeding it, so I know it wasn't a low voltage issue. I've decided to buy a new radio system, that makes 5 planes I've lost in a year to the exact same lockout issue. It's frustrating, because I'm a good pilot... I haven't crashed a plane from pilot error in half a decade at least. It's always these darn receivers that just decide to go AWOL.

Doesn't make me feel any better, a lost plane is a lost plane.

I've already stripped out the gear and started on the 2nd one. Boy am I glad I got two of them! You know a plane is awesome if you toast it and immediately want to build another one. It was that much fun to fly.

I expect the 2nd build to go very quickly, since most of the time I spend on a plane is trying to figure out how to put everything in. There's only a couple of things I'll change. 1st, I'll use metal clevises (just to be safe), and 2nd, I'll do a pull-pull elevator too. The pull-pull rudder worked great and saved on tail weight.

I'll probably settle on a 5S 5000mah pack. My original 5S 4400 maiden flight felt plenty fast, and I still had 3.9 Volts in each cell when I landed, so a 5000 pack will give me great speed and great duration. The 13x11 APC is a great prop for this.

The good news is, I got video of the maiden. The bad news is, my video guy didn't get the crash on video. Bummer. According to him, my big fat head was in the way. My head does seem kind of big when I'm wearing my fur hat.

I'll try and get that video processed and up after work tomorrow. It's okay to go ahead and make fun of me, that fur hat is pretty funny looking. But it keeps my head warm and dry, so I just take the teasing like a man while all my flying buddies stand around with cold red ears and wet heads.

I guess my biggest question at this point is, how in the heck are you guys able to balance this plane with a tiny 36mm motor in the nose, or even a 42mm, and a whimpy little 3600 mah 4S battery pack? I mean that's like a pound lighter than my gear was, and all that weight is in my nose. If anybody can actually build this plane at 6 lbs without adding a lb of weight in the nose, I'll be seriously amazed. I actually made my tail lighter than stock using a pull-pull rudder system, so I'm not seeing how that's possible.

SAPSPIT - I didn't do anything to strengthen my nose when mounting the motor. I needed 2 centimeters of spacers to set the motor back a bit so that my spinner would line up properly. It was solid.
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Old Feb 15, 2010, 07:56 PM
Glenn
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United States, WI, Oconto Falls
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I'm sorry bout' the crash Todd, you certinly can take a loss of a plane alot better than me! Hope you have better luck with the second one.
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Old Feb 15, 2010, 09:13 PM
Cut the yellow wire
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United States, NJ, Trenton
Joined Jan 2004
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Todd-- Great news on the maiden but sorry to hear about the crash. That sucks. You've got a good outlook on it though. I get less upset when a crash is my fault than when there's an equipment failure. I expect me to screw up now and again but not my radio! A buddy of mine and I were discussing whether or not to go 2.4 on some larger scale planes and big fast gliders and we decided to go 2.4 on the smaller models but to stick with 72 for the bigger models. Personal choice I guess. Both of us have TX's modified to select between 2.4 and 72.

In any event congrats and condolences at the same time. I may have been first to buy bit you're the first to fly! Can't wait to see the video (YouTube it so I can watch it on my phone at work tomorrow).

Mike
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Old Feb 15, 2010, 10:09 PM
Team 3DHS
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Winds of Change...may I ask what types of BECs you were using? Linear or Switch-mode? How did you have 2 BECs "feeding it"? (How were they hooked up?) If they were both switch-mode...that right there could very well have been your problem. From what I understand, you can't have 2 switch-mode BECs working together (wired in parallel)

I'm still curious on why/how you had 2 BECs feeding the receiver?

Just trying to help you (and me) figure out what happened...
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Old Feb 15, 2010, 10:28 PM
TMO
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Windy,
Sorry to hear of the loss. I salute you and your attitude. To endure is often greater than to dare and only those who dare to fail greatly can ever achieve greatly. It just sucks when it's the equipment fails.

Damn that radio- that's intolerable. Although it's little consolation, we fly big stuff around here on spektrum and futaba with no issues. If you went back to FM I wouldn't blame you though. And I'd be on the phone with Hitec......

Was the 4" at root CG good, from what you could tell, incidence aside?

It's funny that you brought up the motor/weight issue- Bob and I switched to the BP A4120-7 in his Spit. We had the 35 on the test stand and weren't real confident in getting 600+ watts sustained out of it. Now with a 1000watt setup, I feel a little better about our maiden. The 35 found a home in another project.

But the weight is what it is. With the much heftier new motor, we're still 6lbs and small change- maybe 4oz. We even had to put a couple grams in the tail. I don't know how he did it. Your experience has me puckering a bit. Whenever I get nervous about it, Bob says: "the real ones went down too ya know." He has your attitude. We'll have our video up just as soon as the snow melts.

BTW, my other favorite customer/friend Phil just bought the CMPro Corsair, and he's doing it up with the robart rotating retracts and everything. That thing is gorgeous too.

Anyway, sorry again.

"we shall never, never, never give up"

-Tim
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Old Feb 15, 2010, 10:55 PM
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ok, looked over all the posts in this thread, and am i the only one using a nitro engine in this plane??? lol. im still trying to figure out how to mount the receiver and batt without being in the way of the rods. think i also want to mount a starter in this thing also, provided there is any room left.
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Old Feb 15, 2010, 11:25 PM
More Combat Please!
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Utah
Joined Dec 2003
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djmoose,

Good question. The ESC I'm using has a BEC in it, it's this one.

http://www.hobbycity.com/hobbycity/s...eed_Controller

This is the fifth plane that I've lost to reciever lockout on the XPS system. Every time I talk to them about it, they say "it's low voltage cutoff, give it more power". So this time I figured I'd let the ESC provide what it could (3 amps), and feed in a second power source from another battery using an independent BEC, found here:

http://www.hobbycity.com/hobbycity/s...oise_Reduction

My receiver can take power in on any channel, but I just used the standard channels. The ESC was feeding power through channel 3 along with the throttle signal, and the independent BEC was hooked into the battery input on the receiver.

All my ground tests seemed to work fine, and the maiden went without a hitch. Seems like if it didn't want to work, it wouldn't work at all.

But let me know your thoughts. This is the first time I've tried doing it this way. If I'm doing something wrong, let me know so I don't do it again.
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Old Feb 16, 2010, 06:33 AM
Team 3DHS
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hmm...so, I'm not that familiar with the XPS stuff.

However, I have two of your ESCs (exact same model) that I will be using in my H&M Corsair and FW190. Those are very decent ESCs with switchmode BECs.

Your stand-alone BEC is another decent BEC (I have 4 of them and have used one a LOT in my TWM Zero EP with no problems.)

Here's what I DO know:

Whenever I've used a stand-alone, BEC, I've been instructed to un-hook the red wire from the throttle connection from the ESC. (disabling the ESC's BEC)

With switch-mode ESCs, they are constantly monitoring the voltage against a reference voltage. (ie...is the voltage 5V? no, it's a little lower. ok...I'm going to widen my PWM to raise the voltage a bit.) << very simplified terms.

When you have 2 switch-mode BECs together, they start to "battle" each other and thus cause problems.

What does this mean? I'm guessing that could have played a part in your problem...however it all depends on how your receiver handles the power...maybe it keeps both power sources isolated? or...does it just put it all onto the same power bus.

Some stuff to think about...

Quote:
Originally Posted by Wind_of_Change View Post
djmoose,

Good question. The ESC I'm using has a BEC in it, it's this one.

http://www.hobbycity.com/hobbycity/s...eed_Controller

This is the fifth plane that I've lost to reciever lockout on the XPS system. Every time I talk to them about it, they say "it's low voltage cutoff, give it more power". So this time I figured I'd let the ESC provide what it could (3 amps), and feed in a second power source from another battery using an independent BEC, found here:

http://www.hobbycity.com/hobbycity/s...oise_Reduction

My receiver can take power in on any channel, but I just used the standard channels. The ESC was feeding power through channel 3 along with the throttle signal, and the independent BEC was hooked into the battery input on the receiver.

All my ground tests seemed to work fine, and the maiden went without a hitch. Seems like if it didn't want to work, it wouldn't work at all.

But let me know your thoughts. This is the first time I've tried doing it this way. If I'm doing something wrong, let me know so I don't do it again.
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Old Feb 16, 2010, 01:10 PM
DELTAS RULE
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tehachapi, CA
Joined Jan 2006
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aww bummer dude! sorry to hear that, but glad it flies so nice!!!!!

i use a airtronics RDS 8000......over 2 years of flying, not a single glitch. i fly them in everything from large warbirds and large jets to foamies, fiberglass, carbon fiber, balsa, even alum skin on my sabre....rock solid, and very affordable.

after a few BEC issues, i strickly use flight packs for rx. you may have had something weird going on with the esc feeding power as well. and using 2 bec's seems odd, never heard of that beeing done either. id look into a A123 pack. very light, and affordable.
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Old Feb 16, 2010, 02:56 PM
TMO
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I don't want to pile on to the BEC thing, but.... The castle BEC is the way to go- or go with a rx battery. Even the switcher's lose some amp capacity when run at high voltage. An hs425 is capable of peak amp draws at 1A+ Four of them plus retract servo(s) have the potential to be drawing 5+ Amps.

The BEC's (both linear and swithchers) are rated at 2s voltage. Even the CC BEC, which has a nominal 10A rating, is only rated for 6.6A continuous at voltages above 12V, and 5A at 24V. Those ESC based switching BEC's are probably not as efficient.

Another advantage with going to a large capacity BEC like the Castle, is that if something happens to the ESC (like the magic smoke comes out in flight), you still have control of your airplane. If you rely on one of the BEC's from the ESC, if something happens you lose control.
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