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Old Feb 04, 2013, 12:17 AM
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St.Catharines, Ontario
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that too.
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Old Feb 04, 2013, 05:37 AM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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What's better , looking fast or going fast, they ask?

I answer, what's worse, looking slow or going slow? But then again, they usually go hand in hand. So it's pretty easy to have both. LOL

The same holds true for going fast.
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Old Feb 04, 2013, 11:04 AM
Carbon fiber is our friend
Steve C's Avatar
United States, CA, Lodi
Joined Feb 2001
4,221 Posts
Having the fan blow back on the tail is something to consider. If you change the angle of the air hitting the horizontal stabilizer, it can affect trim quite drastically. Back in the 90's, I built a racing Pitts and fortunately made the stab incidence adjustable. Air from the top wing was driving down on the stabilizer and causing the nose to pitch up. I ended up with +3 deg on that for neutral trim.

I'm sure some small adjustments to the "fan on pylon racer" could have it behaving itself just fine.
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Old Feb 04, 2013, 12:22 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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The problem is that the trim can change drastically with the power level/efflux speed. I don't think that pdawg ever solved those issues on his Blowdart. It was basically like the model above, but in a 30mm fan size.
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Old Feb 10, 2013, 10:58 PM
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Canada, ON, Mississauga
Joined Nov 2011
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We have started well ,wing testing , Maiden #8 B58 wing shape finally succeeds , power held back to a 4 cell Nano , HET blade, but flying at mostly less than half throttle . The EDF tube under the delta makes it balloon when full power is applied . Partial video caught by a friends cell phone , more to follow .
B58 Experimental (1 min 16 sec)
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Old Feb 11, 2013, 12:09 AM
BVM Viper Fever
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United States, OH, Dayton
Joined Apr 2004
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Quote:
Originally Posted by Knife Liddle View Post
The problem is that the trim can change drastically with the power level/efflux speed. I don't think that pdawg ever solved those issues on his Blowdart. It was basically like the model above, but in a 30mm fan size.
No attempt was ever made to alter the original design. This is distinctly different than attempting to solve an issue. The pitching tendency was anticipated long before the first flight and definitely not a surprise. Any changes to the original design imo would have resulted in a slower airframe. Instead I learned the unique flying qualities and flew the model accordingly. Not every model is supposed to fly like a piper cub...with high speed stuff it seems each model has its own personality. It can be fun learning those nuisances. The Blowdart was never crashed and it was retired after winning. It was never meant to be a sport plane. You'll see in the video it was a very solid flyer when it came to going fast in a straight line.

Blowdart 30mm edf on 3 cells (3 min 23 sec)
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Old Feb 11, 2013, 02:29 AM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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Good job Rocketboy! I enjoyed your video. Thanks for posting.
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Old Feb 12, 2013, 09:28 AM
Electric Nut! Zirfnat!
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Canada, ON, Toronto
Joined Feb 2007
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Quote:
Originally Posted by Knife Liddle View Post
Good job Rocketboy! I enjoyed your video. Thanks for posting.
That was me standing next to Scott during the flight
It has come a long way since the first test flight. Hopefully he can get the rest of the problems worked out and get that thing screaming across the sky. We'll see how fast it can go. Nice work Scott!

Hey Lee, I've been reading this thread and was wondering if you ever test flew your bird. Looks awesome BTW.

Eric
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Old Feb 12, 2013, 05:43 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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Thanks Eric, no I'm still fiddling with the power system, and life seems to be getting in the way some too. I may put a lower powered system in it just to get it in the air and dialed in. Hopefully I'll do a maiden in the next few weeks.
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Old Feb 12, 2013, 05:51 PM
High Dynamic Thrust
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United States, FL, Mt Dora
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well put pdawg. every model is different with its own characteristics. some good some not
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Old Feb 12, 2013, 10:26 PM
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Canada, ON, Mississauga
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Impala under construction with mods!
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Old Feb 16, 2013, 05:20 PM
Victim of C.D.O.
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United States, TX, Lubbock
Joined Oct 2007
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FINALLY I got my Spear up and moving!

The first Spear was plagued with little problems that led to big crunches.
Took my time on this build, and followed my tried-and-true power system approach of working my way up the power scale so there are no surprises when it doesn't hold up like it should on paper.

Really it's just such a relief to have it flying well. Was getting seriously frustrated with it for a while there. Now I got something to build on.

This thing sounds good...
Not moving overly quick, but it still has lots of room to grow.
And it sounds gooood...


Spear 8S maiden (4 min 6 sec)
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Old Feb 16, 2013, 05:52 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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It does sound really good, but some of that whoosh sound may be from turbulence around the intake area since it`s probably not from the 5 bladed rotor. They always sound better live than on video, and it sound great on vid, so I`ll bet it is awesome in person.

I set RC Speedo at 50 F and it`s showing 131 and 132 on two of the middle passes. It didn`t want to read the final pass. Not bad. Congrats on getting something in the air. It`s more than what I`ve done.
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Old Feb 16, 2013, 05:57 PM
Ginger or MaryAnn ??
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United States, TX, Garland
Joined May 2005
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Intake is choked down to far I think. He is going to have to open up intake a little more as it looks like it might be 60-70% FSA. Not to bad though for 1800watts.
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Old Feb 16, 2013, 06:00 PM
Victim of C.D.O.
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United States, TX, Lubbock
Joined Oct 2007
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Thanks Lee. The intakes are very smooth, so there shouldn't be much in the way of turbulence.
They may be too small though. I took a stab at it when fairing them in to get rid of the "pie plate" intake of the stock Spear smooth the air out, so not really sure what size they should be.
That's part of the equation, though. Intake area will go in the geeky data book along with thrust tube, blade pitch and area, and the speed, watts and RPM. Only with a bunch of tests can a big picture start to come together.
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