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Old Feb 16, 2011, 10:03 PM
"Jesters" KC-135 Demo Team
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You are close, the Lawton -Fort Sill Army range is 20 miles from the Air Force base. The day of the flight there was a wayward shell that hit dead grass. It burned for three days...
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Old Feb 16, 2011, 10:14 PM
On the Edge of Space
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Exit 4, South Jersey, USA
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Originally Posted by kc135boomer View Post
You are close, the Lawton -Fort Sill Army range is 20 miles from the Air Force base. The day of the flight there was a wayward shell that hit dead grass. It burned for three days...
Gotta keep a close eye on those cannon cockers.
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Old Feb 24, 2011, 11:14 AM
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Okay, I've been reading much of this thread now that my SR-71 kit is sitting in my garage staring at me. Mocking me. (I can hear it..."So, how ya gonna wreck me this time? Another poor setup? Dumb thumbs? Wrong throws?")... There are various power combos and I want the best of the best. Amps/Watts/Draw Oh my!

I would like to use 4S. Am I looking to go 4800s or 5400s? 40amp Pentiums? 60? Or a whole new power config setup altogether (after all, the thread started two years ago)?

MUCHO thanks in advance all you seasoned Habu's!
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Old Feb 24, 2011, 03:25 PM
Wonderfully Wicked
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For 4S go the Wicked 4000 on a pair of 40 amp ESC.

Don
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Old Jul 08, 2011, 03:54 PM
Overconfidentii Flyis Caninus
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United States, WI
Joined Jun 2007
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Don,
I am putting together a NitroPlanes SR-71 and am using a pair of your Wicked 4800 motors and the Hobbywing Pentium 40A ESC's. They showed up earlier this week along with some other goodies. Thanks!
After reading/looking thru the threads of this build log I am not sure if I should mount the motors to the EDF housing using just the two screws that come with the motor and standoff or go with four. Also, my SR-71 kit came with aluminum 'rings' that I believe are to insure the motors (other brand I assume) are kept centered when mounted. They may also act as a stiffener. I can't use the aluminum rings as is; the ID of the rings would have to be opened up probably 0.010" (diameter) or a bit more to get the nose of the standoff to fit snuggly inside of it. Let me know your thoughts on this. I will post pics of what I am talking about in a bit.

Thanks.

Mike
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Last edited by WileCoyote; Jul 08, 2011 at 04:13 PM. Reason: added pictures
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Old Jul 08, 2011, 04:43 PM
Wonderfully Wicked
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The aluminum ring is for inrunner motor and is not needed. You can add two more screws if you want, you just have to drill the holes in the plastic with a 1/8" drill bit to fit the 3mm screws in to it.
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Old Jul 08, 2011, 05:24 PM
Overconfidentii Flyis Caninus
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Thanks Don for the reply.

I noticed on your SR-71 the EDF fans are 5-blade and mine are 6. Do you think the 6-blade will draw more amperage and will the 40A ESC's handle it?

Thanks,

Mike

Here are two more photos showing the fan/impeller assembled onto the EDF unit:
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Old Jul 08, 2011, 06:15 PM
Wonderfully Wicked
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The 6 blade fan pulls the same amps as the 5 blade fan I used in my build.

Don
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Old Jul 22, 2011, 12:08 AM
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Arlington, TX
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Is anyone still flying and/or building this bird besides me? My kit from Nitro Planes will be here tomorrow this afternoon and I'm chomping at the bit to "get 'er done".

OOOOOPS ! Dumb question. I just looked at the date of WileCoyote's post.

Maybe some of you more experienced guys could help me figure out a couple of things. I plan to use the included fans (after I balance them) and I have two Exceed 5000kv motors and two 40amp ESCs to control them. What kind of performance can I expect on a 3 cell battery pack in the 30C to 40C range? Do you think I could get away with using a 4 cell battery with these motors?
If I can get the performance Don got with his bird I'll be very happy. At my age, I don't think I could see it if it went much faster.

I've read the entire thread here and all of this info will be of great value to me as I build mine. I plan to keep it simple and use the stock control system but, will definitely add thrust tubes and plug the exhaust.

This is going to be a fun project and a good flying plane ...providing I get it right the first time..

RJ
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Old Jul 22, 2011, 06:41 AM
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Hi RJ. I'm also working on one...as you noted. It's on the 'back burner' for the time being until I get my NitroPlanes A-10 done, which should be this weekend. I was hoping to have it done and flyable for the AMA 75th Anniversary but other things (work) got in the way.

My plan is to also balance the factory fans, add thrust tubes, install LED afterburners, upgrade the retracts and wheels, add carbon fiber for increased strength and rigidity and maybe add functional rudders. Whew....so much for being ARF! I'll be posting pics and information as I progress on it.

When your plane arrives let me/us know how many blades the fan units have, etc. Pictures would be good. I'm curious to see what the similiarities and differences your ARF is from mine and the others who have posted here.

Mike
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Old Jul 22, 2011, 09:20 AM
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Originally Posted by WileCoyote View Post
Hi RJ. I'm also working on one...as you noted. It's on the 'back burner' for the time being until I get my NitroPlanes A-10 done, which should be this weekend. I was hoping to have it done and flyable for the AMA 75th Anniversary but other things (work) got in the way.

My plan is to also balance the factory fans, add thrust tubes, install LED afterburners, upgrade the retracts and wheels, add carbon fiber for increased strength and rigidity and maybe add functional rudders. Whew....so much for being ARF! I'll be posting pics and information as I progress on it.

When your plane arrives let me/us know how many blades the fan units have, etc. Pictures would be good. I'm curious to see what the similiarities and differences your ARF is from mine and the others who have posted here.

Mike
Wow, you really plan to "pimp" your ride. Sounds like an ambitious but, great plan and I'll bet it all works out great. I'm anxious to see yours finished.
I'll take and post pictures as I go through the build but, will have to put the camera on the build bench so I don't forget. I usually get so involved in the build I forget the pictures. My "forgetter" is working overtime these days.
I too plan to reinforce with CF where necessary. It's great stuff.
Didn't realize there would be differences in the kits coming from the same seller but, I'll post the blade count, etc. here for comparison.

Don't want to forget to thank the Pioneer on this project ....Thanks Don for all you've done to help us. Your templates, experience, and expertise will be invaluable during my build.

RJ
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Old Jul 22, 2011, 12:01 PM
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I keep going through airframes like I change clothes. Don't pelt me with tomatoes but I ended up using a different power plant (nothing personal, I just was presented with a great deal on a different setup...I still plan on having a Wicked-powered SR-71 one day)...

I'm waiting on my next airframe from Hobby King. They went out of stock after I placed my order a month ago and I still wait. I got Joe 1320's AMAZING LED system ready and waiting, I can't wait. I tried doing Don's thrust tube mod but I just couldn't seem to get it right. Do you tape the ends of the thrust tube to the fan housing unit before you install the motors? I couldn't keep them taped to the fans. I really need to do this mod since I understand it really gives the 'Bird that additional thrust you need for folks like me who hand toss.

The next question is: For those who do hand toss, what is the best area or method of gripping? My hand tosses are always pure drama because I don't have a solid grip on the base when I let go so she's all squirrelly until I get that vital air moving through the nacelles.

My flying fields are all grass so I don't even bother installing LG.

I had an accomplished RC flyer hand toss her the last time and he tossed her straight into the ground at WOT.

I did fly my last airframe at a fly-in and it was by far the biggest "stop what you're doing, turn and watch" flight of the day. SO COOL!
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Old Jul 22, 2011, 01:02 PM
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.....I'm waiting on my next airframe from Hobby King. They went out of stock after I placed my order a month ago and I still wait.

Why wait? Nitro Planes has the MaxJet kit version for sale at $60. Is there any difference between the kits?

Yep, the blackbird is a show stopper and I love to see them fly. Got to see one on the ground and the air while stationed in Korea in '79. The pilot did a fly-by after takeoff and shot her straight up at the end of the runway and she disappeared quickly into the wild blue yonder on a clear day. Wow!
I still think there's some alien technology in that bird.

RJ
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Old Jul 22, 2011, 03:07 PM
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Don't even get me started on the alien technology stuff. I'm a big UFO buff!

(One of the many reasons I love that bird).
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Old Jul 22, 2011, 04:26 PM
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USA, CA, Oakley
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Just maidened mine this morning. Here's my setup:

Nitro Planes SR-71 airframe
Don's Wicked 4800 w/ EDF's and balancing (thanks Don)
Two 40A Pentium ESC's
Tower Pro MG90 servos all around (except the nose gear steering which is a SG50)
Thrust tubes per Don's setup exiting 80% of FSA.
Two Sky Lipo 3S 2200 40C.

AUW 2lbs 15oz
905 watts at 80amps peak according to my meter.

I cut open the bottom of the plane to give me room for the wiring, and plenty of space for battery positioning. Used a piece of FFF and parts from the battery and receiver cages to secure the opening. I also reinforced the top of the fuse where the two halves meet with carbon fiber square tubing to provide additional strength. A 1/4 length of toothpick into each of the three vanes of the inlet cones through the nacelles to hold them in place. A touch of black paint hides the tip in the nacelle. My hinges were pretty solid, but I still added blenderm over each hinge, top and bottom, as I do with ALL my planes. Cheap insurance. Also, on my arf the exit nozzle covers were loose and one popped off when I was installing the exit rings. I removed both with ease and re-glued them in with foam safe CA.

Rates were set up per advice here at 25mm for elevator and 15mm for ailerons, although I switched to high rates on the aileron in flight to enable tighter turning in the limited space I had to fly. CG was set at 75-80mm from front of nacelle.

I set about 3mm of up trim and hit full throttle to take off. After about 45 yards (~135 feet) it took off. A bit more up trim and right aileron were required to trim. I ran out of air space quickly and discovered the stalling tendencies of the plane were not exaggerated. Without a fair amount of throttle behind it the plane falls pretty quickly. As others have mentioned, this plane loves to fly straight, fast, and level and nothing really more. It eats up space quickly as it gets going pretty fast in a level line. The plane is big which helps visibility, but it is certainly not a parkflyer. The weight of my setup made it especially touchy and turning was always the challenge. Turns had to wide and fast, or potentially fatal. I spent most of my time at 80% -> Full throttle. Anything less than 60% was spelling trouble. When it came time to land, the fun began. The plane comes in hot, and reducing the throttle makes it drop fast. You're not going to flare this plane much either. I overshot my landing area and had to come around again. With practice I'm sure I'll become more proficient, but I would suggest planning some extra time to become comfortable with your approach on the maiden. I was only up for about 5 mins and my batts were at 3.7v afterward. The stock gear does not lock well and although my MG90 held up on landing, a hard turn that followed collapsed them.

I'm thinking about removing the retracts to eliminate some weight, and hand launching. The retracts either need to be upgraded or not used at all. I was considering different packs as well to eliminate some weight, but after weighing my 3S 2200 batts, it's negligible:

Sky Lipo 3S 2200 40c - 6.9 oz
Turnigy nano-tech 3S 2200 25-50c - 6.3 oz
Turnigy 3S 2200 30-40c - 7.0 oz

Going to a smaller capacity pack to save weight compromises flight times, so it's a wash and not worth it IMO.

The best advice I can give for maidening is to have plenty of runway, plenty of airspace, and lots of altitude before turning the first time. Keep the power on it through turns and apply a good amount of bank angle until you get a good sense of it's stall point. Not a beginner EDF at all.

-Eric
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