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Old Apr 30, 2012, 07:23 PM
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Thanks for the info, dLdV, it was exactly what I was hoping to hear, much appreciated. I can quit worrying about the maiden now.

Galand, the retracts are Chinese, no-name avaialble States-side from several sources, the ones I used are the smallest ones at around 20 grams each, they come with a metal trunion block and 3 mm strut mounting holes which makes them ideal for 70 mm size jets. I get mine from Toysonics in California who have been excellent in their service level in terms of getting orders out. I haven't had to deal with any issues with them so far. Here's the link for them: http://www.toysonics.com/digital-ser...5094m-1pc.html

LK2TINKR
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Old Apr 30, 2012, 07:51 PM
Ennnnncommmming!!!!!
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Bellevue, WA
Joined Sep 2008
920 Posts
LK2TINKR- My three 262s vary widely in weight.
#1 is 1050 grams with landing gear.
#2 is 882 grams as a nacelle lander.
#3 is 1010 grams also a nacelle lander.

I should note that all three have been fiberglassed, polyC'd and painted.

#1 has a battery access in the nose. I found it to be more of a pain than helpful.

I like your convertible top and never thought of opening that portion of the airframe. Beef it up well as the airframe will break there on a crash landing.

Can't wait to see it fly!
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Old Apr 30, 2012, 09:41 PM
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Quote:
Originally Posted by LK2TINKR View Post
Galand, the retracts are Chinese, no-name avaialble States-side from several sources, the ones I used are the smallest ones at around 20 grams each, they come with a metal trunion block and 3 mm strut mounting holes which makes them ideal for 70 mm size jets. I get mine from Toysonics in California who have been excellent in their service level in terms of getting orders out. I haven't had to deal with any issues with them so far. Here's the link for them: http://www.toysonics.com/digital-ser...5094m-1pc.html

LK2TINKR
Yes, from the looks I guessed they were PingZheng. I have a bunch of them on the FMS 1400mm foamies, but these seem to be a size smaller, good to know they exist.
http://www.pz-servos.com/en/products...etail&P_Id=835
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Old May 01, 2012, 06:59 AM
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C/Z,

Thanks for the info, good to know that my weight will be close to what has already flown successfully. I re-inforced the enlarged battery bay with some 3 mm carbon tubes and installed two 6 mm carbon tubes on the insides of the hatch opening, preliminary eye-ball testing shows that the area is now plenty strong. Once I join the fuse and the wing, it will be a little stronger plus I'll be adding 2 more carbon tubes in the front joint between the wing and the fuse to take care of the landing loads on the front strut.

Galand, thanks for posting the manufacturer's site; I never knew who made those retracts.

Hope to be able to work on the project some more this week...

LK2TINKR
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Old May 05, 2012, 04:52 PM
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Update

Greetings everyone,

Got some more work done on the schwalbe last night and again this afternoon. Now, the airframe construction is complete. I have installed all the servos, the tail feathers and glued my wing on. I added a single carbon spar in the wing, just ahead of the main factory, 2-piece spar. For the cockpit area, I added a pair of 6 mm diameter, thin-wall carbon tubes just under the opening edges, they run a couple of inches past the ends of the opening on each end. Overall, the frame is strong and stiff so I'm attaching the cockpit with some strong magnets.

I decided to use the sky angel, 6-blade fans and a pair of 4000 kv, 28 mm outrunner motors. They pull around 30 amps initially for around 440 watts and the thrust is around 16 oz., after a minute, they're at 27 amps, 380 watts and 14 oz. of thrust steady. The motors are rated at 26.5 amps so they should be ok for this level of power. When both motors are hooked up to the same battery, i expect the power may drop to around 330 to 350 watts per motor which will be close to my original goal.

Now that the power train has been sorted out, I need to finalize the installation of the ESC's (inside the ducts) and the nacelles onto the wing and she will be ready for the final sanding and paint
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Old May 07, 2012, 03:12 PM
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Is that 14oz total thrust from 380 watts?

I'd expect more like 14oz *each*, so more like ~30oz total for ~380 watts.

Mine flies on 360 watts with home made motors and GWS rotors, and it's got near 30oz of thrust. I haven't measured it in ages, but it was much, MUCH better than 0.5 thrust-weight...
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Old May 07, 2012, 07:13 PM
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Hello rdeis,

The test was with 1 fan, so 28~30 oz for both fans. Power was 380 watts for 1 fan as well, so around 760 watts for both fans. Don't forget, these are 50 mm fans not the stock 64 mm fans. The smaller fans generally have less thrust effciency than the bigger fans. I'm fairly confident that 28 oz will fly the plane comfortably, I'm finishing around 38 oz, ready to fly so T/W ratio of 74%. I'm getting ready to attach my completed nacelles to the plane which would be about the last thing I'll need to do before she's flyable. How much did your bird weigh?

LK2TINKR
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Old May 08, 2012, 02:50 PM
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Quote:
Originally Posted by LK2TINKR View Post
Don't forget, these are 50 mm fans not the stock 64 mm fans.
Ah- that makes more sense. It still seems like you should be able to do better? You're using literally double the power and getting the same, or a little less, thrust than I did with twin 64s.

Quote:
How much did your bird weigh?
Around 35oz. Pneumatic retracts and poly/glass skin. I dropped off a nacelle on a rough landing last summer and put the nacelle back on crooked-- made for a very exciting post-repair flight!

Got her down OK, though, and she's waiting in line to get that nacelle mounted correctly before going up again. Maybe in time for the June Warbird meet in Falcon...
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Old May 08, 2012, 09:21 PM
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Hello rdeis,

Thanks for the reply. I dug around the threads and found your build, you were definitely an early adopter. I remember when it came out I was turned off by the humongo fans and never did take a second look until the 2 kits came my way at the field a couple of weeks ago.

As you have pointed out, these fans are not all that efficient for static thrust but the other factor is eflux velocity which they seem to have an advantage over a larger fan. The tail pipes are around 40 mm which is right around 80% FSA for these fans and the eflux velocity is easily over 100 mph, so I'm hoping the fans will have more thrust at flight speeds and help push the top speed higher.

I'm on the home stretch with the build, one way or another she'll be proving her mettle soon. Good luck getting yours back in the air. BTW, have you seen the 59" w.s. 262 that Dynam is bringing out, it looks like a must have for sure...

LK2TINKR
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Old May 08, 2012, 09:42 PM
Stop scaring my donkey!
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Remember, maximum groundspeed before rotation, then flatten the angle of attack until the fans "bite," then climb like a sunny beach!
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Old May 08, 2012, 10:48 PM
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Quote:
Originally Posted by LK2TINKR View Post
the other factor is eflux velocity which they seem to have an advantage over a larger fan. The tail pipes are around 40 mm which is right around 80% FSA for these fans and the eflux velocity is easily over 100 mph, so I'm hoping the fans will have more thrust at flight speeds and help push the top speed higher.
It will be plenty fast, those extra 300 watts have to be good for something! Heh..

Actually, the 80% FSA exhaust is the reason you're so power hungry. Fans are happiest at around 95%. Restricting it further can indeed make you more speed, but at the cost of power and therefore flight time.

Haven't seen the bigger one yet, that would be really fun...
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Old May 12, 2012, 01:13 PM
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She flies!

...
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Old May 12, 2012, 01:26 PM
Stop scaring my donkey!
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Congratulations, you avoided the entertaining but deadly GWS 262 cartwheel!
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Old May 12, 2012, 01:35 PM
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She flies!

Greetings all,

After a busy week, I was able to get back to my build Thursday night and a few hours more last night and the plane was ready for a test flight (minus paint). All systems are installed and operational and tested. There are still some reinforcements that I would like to install for the nose gear area but the airframe weight has already ballooned to just over 900 grams or 32 oz, with the 8.9 oz battery I was looking at 41 oz for a take off weight. This works out to about 22 oz / ft^2 wing loading so I decided to do the maiden before adding any more weight of any shape or form. I did paint the cockpit area and added a home-made luftwaffe jockey before gluing te canopy on. I also just taped the nose cone in place for now, I need to make it removabe for service access to the nose retract so it needs to be removable.

I soldered up a brand new 2200, 45/90 C nano-tech 4-cell and charged it up. First test showed 63 amp at approximately 900 watts Thrust was good too, it almost seemed 1:1. I re-charged the pack after my short test and went to bed fo an early start today.

The weather was cool and a stiff breeze was already up by 8:30 am. We're not allowed to fly until 9:30 so we cooled our heels while we waited. I realized I didn't have my camera so if the plane was lost on the maiden, I wouldn't have any record of the event but I was already set up so decided to go without any video

After flying some of my other planes, and with the wind picking up, I decided to go for it. The first attempt to take off resulted in a near disaster as one main gear wheel locked up on application of full throttle resulting in a spin. I used 3 mm bolts as axles and the one that was being "tightened" by the wheel rotation torqued up and locked the wheel. A little CA on the bolt and a quick adjustment on all the wheels and she was ready for another try. I rolled on the throttle smoothly and the fans went on song after a couple of seconds, she took off down the runway at an incredible rate and I held off from applying any elevator as advised by the group. After it seemd like she was going 50 or 60 mph, she lifted off without my prying and started a fairly steep climb out. It was not too sudden and I applied a little bit of forward stick to keep her from ballooning. Gear up, turn downwind and throttle back to around 70% and she was cruising really fast. Everyone on the flight line is saying stuff like wow, holy shxx, etc. The trim was a little nose heavy so I trimmed that out. Roll rate with the reduced length ailerons was just fine on my low rates which were set to 60% with 20% expo. I also mixed in 30% rudder into my ailerons and the turns were nice and groovy just needing aileron input and then elevator to adust the radius. I wanted to test the stall so I climbed high and throttle back with zero flaps and the gear up. She seemingly hovered into the 12~15 mph breeze and then snapped into a stall by dropping the left wing. I powered back up knowing that she will slow down reasonably well for the landing. The high wing loading required a fairly high throttle setting and she would start decending at anything below half throttle. After another couple of circuits I came in for the landing. Apprximately 1/3 throttle and full flaps resulted in a nice approach and a nice landing into the breeze. I remebered to breathe afer that.

Overall, the plane did not fly like a brick as I had feared . Now that I know it flies fairly well, I'm going to add a little bit of reinforcement around the nose gear and apply a paint job. Here are the stats of my plane at the time of maiden:

All up weight: 1163 grams (41 oz)

C.G. 65 mm from wing joint

wing loading: 22.4 oz/ft^2

Power: 900 watts

LK2TINKR
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Old May 12, 2012, 02:03 PM
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Long Island, NY
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Congratulations LK@TINKR
Gear and flaps look so good I might consider building another one!
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