|May 28, 2007, 12:35 PM|
Great Plane PBY Catalina build A-Z
I like to finish the plane and get a flight on it before posting a build thread so I know if what I did should be recommended to others and I can advise others not to make any mistakes I may have made. That said...
53.5" Wing Span
395 sq in area
18-19 oz/ sq ft wing loading (16.4 per my final weight)
This was the easiest ARF I've ever built. All the parts fit together wonderfully and Great Planes did a fantastic job keeping it light and setting it up for their motors.
2 lbs 13 oz -- Final RTF weight (w/battery)
Kokam 2000mah 15C --- three year old and yet very strong 3 cell
19.2Amps 209W 11.0V Static test
Commonsense 2100 15C -- two year old but still fairly stong 3 cell
16.5A 166V 10.1 V Static test
A short flight with each pack.
4.5 minutes on Kokam took only 610mah, escs at 107 F, battery 82 F. 10 minute flight should be no problem.
4 minute flight on CS pack used 475mah, esc at 105F, batt 92F.
On both set ups the packs are as far forward in the nose as I could get them. The CS pack is 6 1/4 oz and no weight added to plane. The Kokam has two 1/4oz weights on the end of it and now weighs 6.5 oz. Both flew fantastic.
The plane does not steer perfectly as you are trying to taxi in the water at very low speed as the water rudder is out of the water. When you give it more throttle the front starts to come out of the water and the rudder in the rear lowers. When you give it full throttle it nearly jumps out of the water. Very quickly gets up. The props do chop the water a little at full throttle when starting from going slowly to full power. Immediately upon getting out of the water you'll never need more than 1/2 throttle to get around as you please and gain as much altitude as you like. This is probably why there is so little amp draw. I noticed no bad tendencies and the 5mph wind seemed to have nearly no effect at all. Landings were the easiest part. Coming it at 1/4 to 3/8 throttle I chopped it and let it glide right down without trying to slow the plane much. It glides right in and skips across the water until finally settling down into the water.
A complete build thread like I do for chinese planes with horrible to no instructions would be an insult to even those of below average reading skills on this plane. Great Planes has provided fabulous instructions that are very detailed and have lots of pictures. I will point out what I did different and anywhere I felt directions could have been improved.
Here is a copy of the provided instructions.
|May 28, 2007, 12:54 PM|
I needed absolutely no servo extensions for this plane. They recommend having total servo lead of 9" for the elevator and rudder servos to reach the RX. The HS 55s have 10". There are servo leads and motor wire leads already provided and installed inside each wing. Also in my kit were two 12" servo extensions that I didn't need.
|May 28, 2007, 01:12 PM|
I have been told that Great Planes ordered 16,000 of these Catalinas and when they received the container there were 160! My LHS got the one I pre ordered but not the one that each HS was to receive for display. He also told me that tower only got 16 total! This would explain why they were gone in such a short period.
Great Planes was out of the escs that they recommend so my LHS asked them to send him the same esc that they private label under another brand name. That is Heli-Max HMXM3000 25A esc. Some esc makers do not suggest using both red wires from the different escs into a Y harness to power the rx and servos. I read of no problems in the esc instructions so I left all wires as is and Y'd all together. No problems.
EDIT: After many flights I have now had the receiver get some condensation on the inside and cause a servo lock up fully in one direction. As the rx dried out all was fine and I've flown since. I am letting it dry thoroughly and will then put the rx inside a large balloon and silicon the end with wires sticking out. I had a semi rough landing that didn't hurt anything but allowed maybe 1/8" water in the bottom of the fuse. I guess it doesn't take much to condensate an rx.
|May 28, 2007, 01:21 PM|
I tend not to use dual rates so I set all control surfaces to move to the maximum suggested throws and programmed in about 50% exponential on both ailerons and elevator to calm down the movement around the middle of the stick.
I put velcro all the way up into the nose and the full length of the battery and found that this made it extremely difficult to get the battery back out as it is pushed as far forward as I can get it in the fuse. I removed the front 1/4 of velcro from the pack and this made it easier to remove. My batteries are not long enough to use the supplied velcro loop attached to the battery tray.
If you are looking for the ability to fly 1/2 the day without pit stopping for a battery I did notice that my 3s 3700mah 20C PQ pack would fit in the plane and was only slightly nose heavy when positioned as rearward as was possible. I prefer a light set up and 10 minute flights are plenty long enough.
Page 3 of this attached thread has a pair of great videos on the full size Catalina. Worth checking out!
|May 28, 2007, 06:21 PM|
If you gently bend and pre-curve the music wire pushrods to about the same curves that are needed, that helps a LOT with drag.
My kit was complete with all parts...sounds like one of the two little boxes that supports the fuselage was empty in your kit. Mine were both full of parts and I think one of those boxes had all the parts you are missing.
I bet you did carefully check both of those fuse support boxes, though. How annoying to get shorted parts on a new model like this.
|May 28, 2007, 07:02 PM|
Wow, thanks! Really appreciate the effort you put into you posting!! I've got a few tough choices to make here in the near future--ie next plane after Alfa Dora. Is it just me, or does thing land a little hot? Seemed pretty quick in the video.
|May 28, 2007, 07:14 PM|
Hand launch would scare me.
It has alot of wing area and plenty of power. It glides very well. Still....
You might try and pull some wing load comparisons with something like the EasyStar which is similar in overall dimensions and easily hand launches. Don't recall the weight on that one. I would be on a hill and toss it for my first attempt.
Agreed that the wing floats would be an issue on landing. Get an easy star for 1/3 the cost. If you get near water I'm sure you could land it on water.
Yep, pretty bummed about missing parts. They did a good job with getting replacements to me quickly.
|May 29, 2007, 04:53 AM|
I wouldn't call it a sail plane but it can really slow down pretty well without tip stall. I think the landing may look faster than it is because the boat bottom is pretty wide and the plane is fairly light and this combo allows it to skip along the surface of the water (almost no friction to slow it) until is slows enough to drop into the water. Think hydroplaning.
I've only had two flights so far and have not attempted to use the flaperons to slow it down or to use a higher angle of attack to slow it down because I'm more afraid of a tip stall on landing than I am coming in with a little speed. Will likely slow it down even more as I get used to the plane. Would like to be able to fly out of any puddle I can find!
|May 29, 2007, 08:42 AM|
Your post has given me confidence so I'll order prior to Towers $30 @ $150 purchase coupon expiring this Thurs.
|May 29, 2007, 10:12 AM|
so carl, how is overall orientation in the air? I'm adding blue stripes and checkerboard onto mine turning it into what i call "Crazy Cat".
|May 29, 2007, 03:49 PM|
Seems pretty easy to follow in the air. It seems like it would be hard to get it upside down and the shape of the fuse makes it pretty easy to tell which way it is going even at a distance. I had three more flights this morning and am still impressed. There was a little bit more cross wind today than on the maiden flights of Sunday. The first flight was a picture perfect landing as there was no wind. I now have takeoffs figured out. Get it going in the direction you want and gun it! Once gunned it takes just a second or so to lift up and travel on the boat looking bottom portion as opposed to a large part of fuse that was in the water at rest. Then it is nearly immediate that the plane "shoots" out of the water and climbs rather quickly. It really builds alot of speed once hydroplaning on the boat portion of the fuse.
1st flight was no wind and perfect skipping landing.
2nd flight was a little more cross wind and I was trying to bring it in without using rudder so it was off by about 30degrees from the direction I wanted it facing. I was using ailerons to correct and one wing float hit first. To my suprise it planed along on that float until the rest came down and it did its skipping for a shorter distance.
3rd flight was likely the worst water landing without anyone dying! More wind, I slowed down way too much by cutting power too early. I think I stalled just above the water and it seemed to nose in and drop a wing at the same time. The water cushioned it I guess as it just popped back up and I taxied it in. Not really a water crash but not much of a landing either. Nothing damaged that I know of. Both motors working to bring it in. Heard a humming that sounded like it was coming from one motor. Unplugged battery quickly. I know at least one motor got wet. The motors are really well covered but there is an air outlet in the bottom of the cowlings and a small gap where prop adapter exits front of cowl.
1st flight with kokam pack and I goofed up my timer. It landed the best, had the least wind but also weighs 1/4 oz more than the CS packs (due to the 1/2oz I added to it).
6 min 15 sec flight on CS2100 used 549mah. This was likely an easier flight than maiden as I was more aware of how little throttle was needed to fly the plane. Did a loop with no problem.
6 min flight on another CS2100 pack used 500mah. One esc is 110 deg and the other 100 deg. Neither are high by any means but interesting one higher than the other. Battery at 99 degrees which is also not a problem. Clearly I can push this to 10 minutes without fear.
I have now added 1/4 oz to each CS packs and will see if this helps the landing. I don't like tail heavy for sure and the lighter weight packs are shifting CG back slightly.
The plane will turn quickly at the max suggested throws but is very docile around the middle where I have around 50% expo. Also noticed that it does not like to turn when the wind is at its back. So don't head towards a large tree and wait too long when traveling with the wind!
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