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UMX B-17

Old 01-25-2016, 02:26 PM
  #26  
firemanbill
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Cool! nice find then.
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Old 01-26-2016, 11:23 PM
  #27  
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Ha Ha, almost had a use for it already...

Maiden flight today, beautiful morning without even a whisper of wind. Pre flight and range check all good. Roll out nice and straight. And it nearly went south from there. I applied too much up elevator, and it was darn close to GB's video. She jumped off the ground, and went vertical!

Time seemed to slow down, I watched as she clawed upward, slowly loosing the battle with gravity. As she lost momentum I went full down elevator, and she snapped 180 degrees, headed down and then I managed to pull her out. Funny this is exactly how my Multiplex Cargo takes off, so I guess practice with it, helped here.

After unclenching a part of my anatomy, time came back up to speed.
At full throttle she was climbing pretty aggressively, took two clicks of down trim and she continued to climb but at a more easy rate.

Backed off the throttle and made a couple of circuits. Set up for a landing and If I say so myself, it was a thing of beauty. She slowly lost altitude, came down on the mains and then settled on her tail.

Man that was sweet! Let's do it again, so I did. This time though was much better on take off. Eased into the throttle, not touching the elevator. She rolled a couple of feet, her tail came up, got light on her wheels, and like the real deal she lumbered into the sky on a shallow climb.

I swear I could hear Pratt and Whitney radials thundering as she rose up and flew overhead.

To add to the effect, the sun had just cleared the nearby rise, lighting up the sky in a blazing red. Silhouetted, with that as the back drop made it look like the real deal coming home from a night bomb run.

Flew her till I could tell the battery was getting low, set up and made a second beautiful landing, followed by a roll out to my feet where I shut her down.
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Old 01-26-2016, 11:41 PM
  #28  
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Originally Posted by Glacier Girl View Post
Ha Ha, almost had a use for it already...

Maiden flight today, beautiful morning without even a whisper of wind. Pre flight and range check all good. Roll out nice and straight. And it nearly went south from there. I applied too much up elevator, and it was darn close to GB's video. She jumped off the ground, and went vertical!

Time seemed to slow down, I watched as she clawed upward, slowly loosing the battle with gravity. As she lost momentum I went full down elevator, and she snapped 180 degrees, headed down and then I managed to pull her out. Funny this is exactly how my Multiplex Cargo takes off, so I guess practice with it, helped here.

After unclenching a part of my anatomy, time came back up to speed.
At full throttle she was climbing pretty aggressively, took two clicks of down trim and she continued to climb but at a more easy rate.

Backed off the throttle and made a couple of circuits. Set up for a landing and If I say so myself, it was a thing of beauty. She slowly lost altitude, came down on the mains and then settled on her tail.

Man that was sweet! Let's do it again, so I did. This time though was much better on take off. Eased into the throttle, not touching the elevator. She rolled a couple of feet, her tail came up, got light on her wheels, and like the real deal she lumbered into the sky on a shallow climb.

I swear I could hear Pratt and Whitney radials thundering as she rose up and flew overhead.

To add to the effect, the sun had just cleared the nearby rise, lighting up the sky in a blazing red. Silhouetted, with that as the back drop made it look like the real deal coming home from a night bomb run.

Flew her till I could tell the battery was getting low, set up and made a second beautiful landing, followed by a roll out to my feet where I shut her down.

Awesome!
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Old 01-27-2016, 10:31 AM
  #29  
Don Sims
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Enjoyed reading about that first flight!
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Old 01-30-2016, 07:28 PM
  #30  
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Originally Posted by fhhuber View Post
Its just a lesson in the need to verify having the CG correct.

One of the local guys flew a plane for over 2 years complaining about how it flew every time...
Eventually he gave it away and I ended up with it ( a few owners down the line)
NO ONE checked the CG before I got it...
I had to add 12 oz to the tail... then it flew fine.

Telemaster (8 ft span) with a 26 cc weedeater conversion grafted on the nose...
they'd been flying it with CG 1/2 inch from leading edge.
Originally Posted by firemanbill View Post
Amazing how many people never check that.

What is even worse is when you set it by the manual and it is so far off it's crazy. Happened on a 27% Pitts of mine. Biggest plane I had ever flown at the time and my buddy who is a RC rock star came out to help that day, glad he did or that plane would have ended itself on the first flight. Best CG was a full inch in front of there forward most recommendation.
I agree gentlemen. Before the B-17 I just plopped the battery in because all of my HH planes up to that point were perfect. The oddest part is I actually checked the CG and I deemed it "close enough" with the battery is came with 100% forward.

Since then of course I have been VERY particular about that as I do not want to experience an issue like that again. Even with my new UMX J-3 Cub I was very focused on making sure that was dialed in nicely.

If is great to see Glacier Girl having a great time with this plane. It truly is a very fun flier to see fly by at eye level nice and slow once properly tuned.

GB
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Old 01-31-2016, 02:53 PM
  #31  
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Well I took #2 out yesterday, was a little windy but what the heck. First this one balances with the cell half way under the fuselage, where the nose cone attaches.

I slid the battery forward to give a little more nose heavy to combat the wind, and was a pretty much uneventful maiden. Okay nearly hit the truck on landing when the wind caught it, but snuck by and landed softly.

Anywho, I removed the inner cowls from #1, and the tape from them to the fuselage. Made up a pair of landing gear/retracts out of wire and control rod tubes. Amazingly they dropped right into the wire channels, all I had to do was remove a slight rise in the foam at the fuselage entry point to have them lay flat. Even better the hole in the center of the wing for the wires to run into and the one in the fuselage allow the arms of the retracts to clear.

Soon as the new servo arrives I'll install it and make up the connections.

I left the lower cowls off,that way I can fine tune the retracts, before notching the cowls for the wheels to fit up into.

Only downside to all this was removing the cowls. Like the other parts, they are taped to the upper cowls at the front. But, from the wing LE back they were glued in. Took some careful cutting with an Xacto blade bent 45 degrees to get them loose. Plus they run the tape over the wire runs under the cowls, so I had to cut them loose too or have the tape I didn't want removed pulled loose.

I'll take some photos of what I have so far, tonight after work.

If this continues to work like it's gone so far, it will be an easy one for others to copy.
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Old 02-01-2016, 01:23 PM
  #32  
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Well as stated some shots of the workings. Once the servo arrives, (now three days since ordered from Horizon, and still not shipped) It will make more sense on the layout. Bare with me.
Attached Images
File Type: jpeg
B17 retract.jpeg (79.0 KB, 473 views)
File Type: jpeg
B17 bottom.jpeg (75.5 KB, 431 views)
File Type: jpeg
B17 top.jpeg (54.2 KB, 388 views)
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Old 02-04-2016, 01:56 PM
  #33  
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Well the Weather Girl lied again yesterday. Said 3 to 5 mph winds and rain in the p.m.
No rain, and if that's her idea of 3-5, I'd hate to see 10-20.

Spent the day discharging packs and cutting up the lower cowls to fit the retracts.

And like always the first one was a bugger. I knew I would have to cut a slot for the retract to pivot through, but didn't realize I also had to do some trimming inside the cowl for it also. Because of the bends to keep the height and wheels centered. And for the cutouts for the tires to fit up into.

Took me 4 hours of cutting, installing, removing, cutting, and so on. Followed by gluing foam back in to places I had cut out. Second one took me maybe 15 minutes.

Got both under Spackle so I can make them look nice again. And figured out a way to do it faster. Next time, I'll cut out the center section of the cowl, slice it lengthwise and then it will be easier to trim up. Once done, just glue em back in.

Orrrrr, Leave the retracts sitting inside of the cowls on the fuselage, and just have the tires fit up into the cowls. Oh well, live and learn.

Still waiting on my servo to show up, so at least I'm still making progress.
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Old 02-06-2016, 03:58 PM
  #34  
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Well change in plans. I redid the retracts to they sit inboard of the cowls. Was a real PITA trying to get the bends all correct to keep the gear inside the cowls, keep the height, keep the tires centered, and then hacking up the cowls to allow proper travel. Least this way the wheels will fit up into the cowls when retracted so it looks right.

Got my servo last night. In a box the size that a pair of shoes would fit in.

Thought I had screwed up when I opened the box. I ordered a long throw servo alright, but missed that it was an off set 70/30 version.

Well good news, two parts. YES, the X-port will control a servo, off the gear channel.
And when used on the gear channel the servo operates 50/50 throws.

Made another mock up and the servo is strong enough to operate the two retract with ease. Now it's a matter of adjusting the short arms on the retracts to get the proper throws.
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Old 02-08-2016, 01:34 PM
  #35  
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SUCCESS!!! Sorta...

It actually works. The servo has just enough travel to fold up the gear. Only after at least a dozen or so bending of control rods to get the correct angles.

Not for the faint of heart doing so, as I had to use a magnifying glass and surgical forceps to do the surgery. Trying to fit the rod and pivots among 6 sets of leads and not catching on something was a PITA.

Thinking I may just go ahead and unplug everything so I can get the board out of the way and then reroute the leads to also stay out of the way.

I probably qualify for micro heart surgery now, working all that stuff in a 1/4" diameter hole.

I'm off tomorrow, so I'll get the rx board off so you can see better the set up. But at least you know it does work.
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Old 02-09-2016, 03:41 PM
  #36  
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Well crap. Somehow I lost the photo of the rx board removed. Oh well, it works!
Shots below show all those wires and rx in place, of course hiding the darn part I wanted to show. And the underside, leads all run behind the retracts, and tacked into place with Beacon Foam-Tac.

Since I screwed up on the photo, I diagrammed the set up so you can get an idea of how it is.

Anywho, I'll get the lower cowls sanded and painted, re-tape the the wire runs and install the tires. She's then ready to go.

Now if the Weather Girl will just co-operate...
Attached Images
File Type: jpeg
b17 retract 2.jpeg (67.1 KB, 417 views)
File Type: jpeg
b17 retract 3.jpeg (41.7 KB, 412 views)
File Type: jpg
retract diagram.jpg (120.6 KB, 425 views)
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Old 02-09-2016, 03:44 PM
  #37  
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Oh and a tip/warning. After hooking everything back up I had one motor not spinning.
So I pulled the plug and reinstalled it. WHOOPS! Remember the board has 3 pins and the motors only use two of them? Well if you plug the motor into the wrong pins it runs wide open!!!
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Old 02-10-2016, 01:02 AM
  #38  
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Well she's back on her wheels.
Got the retracts buttoned, and started putting her back together. Along with the retracts I'm modeling her after the YB-40 Gunship variant. Still have to add the second upper turret, but got the twin .50's installed for the side gunners, and the six gun chin turret done up. Even snuck in some weathering.

Couple of notes. Wheels won't fully retract into the cowls as due to the needed height of the gear the wheels hit the back of the gearboxes when folded up.

But a good thing or two. One, if someone goes brushless on these, it will allow more room, and the full travel hasn't been used up on the servo. And if the retracts fail to deploy, the wheels stick out enough keep the bird off the ground. May scrape the blades but the rest will be safe.

The retracts add some spring or a bit of suspension if you will. Should help with the bounce when someone comes in a little too hot.

What else? Oh, the servo I used is just one of the aileron long throw versions, 3.5oz. of torque, just enough. I've already gone ahead and ordered the heli version for my other one. It packs a whopping 11oz. of torque, to help with any binding or such someone may run into. It's only like $3.50 more then the other so no big deal.

Hopefully the weather changes tomorrow, today was 10-20 winds with gusts to 35+ so not test flight weather.
Attached Images
File Type: jpeg
b17 retract 5.jpeg (39.9 KB, 412 views)
File Type: jpeg
b17 retract 4.jpeg (43.7 KB, 402 views)
File Type: jpeg
b17 retract 6.jpeg (20.5 KB, 396 views)
File Type: jpeg
b17 retract 3.jpeg (55.2 KB, 389 views)
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Old 02-12-2016, 01:57 AM
  #39  
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Well she returned from a test flight unscathed. Roll out was normal, no abnormal traits.
Landing was honestly a thing of beauty. I swooped in and instead of a bounce I got a shock like effect, gear took the load settled slightly and she planted her mains. No bounce just like the gear took the load and compressed to accept it. I'm pretty sure she would have bounded back in the air if the stock gear was in it.

So concept proven, I shall start on #2, for a finalized product.
I'll try and do a better job with measurements, and of course photos.

oh nearly forgot, was so happy with her performance I finished up herYB-40 conversion. She now sports a 6 gun nose turret, a pair of single nose guns, lower turret, twin .50 for the side gunners, tail guns, and a pair of top turrets.
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Old 03-03-2016, 03:07 AM
  #40  
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Update: Second one converted using the stronger servo, and it works like a charm.
I listed build photos and descriptions over on RCG.
http://www.rcgroups.com/forums/showt...57337&page=162

She's a beaut in the air. Take off, and the gear slowly lifts up into the cowl, leaving just about the same amount of wheel hanging out like you would see if you used the optional wheels up version instead of the stock gear.

Come around on final, hit the switch, and the gear slowly extends to full travel.

And I'll be honest it has more shock absorbing capability then the stock gear it seems.
I made one of those not so pretty landings where normally she would have bounced way back up in the air and gotten ugly. Not now! Instead of a big bounce, all she did was a little hop and sat right down.

I'd call this mod a success.
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Old 06-23-2016, 04:01 PM
  #41  
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It seems there are two approaches to this aircraft, either add nose weight or give it down trim. Which do you recommend and why? Is the battery change to help with CG primarily or just performance? If you give it down trim, how much?
And how much throttle for hand launch, vs. how much for ROG takeoff? I got one of the $69 Black Friday 2015 ones but have been too chicken to fly it.

What would the best source be for the Turnigy Nanotech 600mah battery?

Last edited by Griff Murphey; 06-23-2016 at 05:04 PM.
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Old 06-24-2016, 10:15 PM
  #42  
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Well I guess this is a dead post or my questions are kinda elementary, my dear Wattsons!
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Old 06-24-2016, 11:15 PM
  #43  
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Generally you solve a CG issue with CG change... and a control surface alignment issue with trim.

The trick is figuring out which you need.

Its SAFER to move the CG forward slightly if there's any doubt about CG, then you take the plane up and do a trim check series of maneuvers, which will positively identify what change(s) might be needed.
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Old 06-25-2016, 02:31 AM
  #44  
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Thanks! I would agree that adding nose weight has advantages over adding down elevator trim. For one thing the trim won't vary at different speeds. However the UMX B-17 has been reported as slightly underpowered... In those cases sometimes trim is your best option. That's why I was hoping to get some advice from someone who owns one.
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Old 06-25-2016, 04:20 AM
  #45  
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I don't own one... but a local club member does and I helped him get it flying right. His needed just a little weight in the nose, then the trims centered was perfect.

There's also minor variances in the center value for the TX sticks of different radios. 2 "duplicate" DX6i's used for buddy box and one needed 4 "clicks" of elevator trim when the other was centered.

These models turn out with varying CG due to natural inconsistencies in the foam density and paint thickness.
Some are dead on perfect CG from the box with the OEM battery placed by the instructions.
Some are tail heavy.
I have not heard of one that was nose heavy yet. (but it could happen)

So... even with supposedly identical stuff... your results may vary.
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Old 06-25-2016, 04:35 AM
  #46  
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Ok I will check the CG as best I can. Thanks!
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