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Author Topic: Born Loser embryo biplane  (Read 2483 times)
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billmz
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« on: April 11, 2013, 02:59:29 AM »

Here are a couple of pictures I took this evening of my freshly completed Born Loser.  Entirely scratch built from the FREE plan from www.flying-models.com .  Finished weight, minus the rubber, is 14.59g. Covered and trimmed with domestic tissue. Hand carved balsa 7" freewheeling prop (weight exactly 1g), prop covered with black tissue for strength and looks.  I haven't flown it yet, but initial test glides across the bedroom onto the bed look very promising.  Soon I will find some approriate rubber and see how it flies under power.
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Born Loser embryo biplane
Born Loser embryo biplane
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
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« Reply #1 on: April 11, 2013, 10:38:12 AM »

Vary nicely done sir! Grin
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Cee Gee
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« Reply #2 on: April 11, 2013, 12:40:32 PM »

Nice model.   Have you ever bought rubber from FAI Model supply?  http://domino-35.prominic.net/A55C2D/fai.nsf/nav?OpenForm&section=71FAA6431B54133886257742006D1051&start=10

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billmz
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« Reply #3 on: April 11, 2013, 01:12:17 PM »

This was my first attempt at an embryo, and now that it's done I see several areas where I can make it lighter. I think I could easily shave 2-3 grams off, and maybe more.

I have not bought rubber from FAI before, but I will certainly visit their website and see what they have to offer.  I have some rubber that I purchased from A2Z a year or 2 ago, I just have to find it as it is still in hiding after a recent move from Illinois back to Louisiana.
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
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« Reply #4 on: April 11, 2013, 03:59:19 PM »

I sell FAI rubber at VERY reasonable prices  Roll Eyes

--george
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lincoln
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« Reply #5 on: April 11, 2013, 08:27:26 PM »

Nice model.   Have you ever bought rubber from FAI Model supply?  http://domino-35.prominic.net/A55C2D/fai.nsf/nav?OpenForm&section=71FAA6431B54133886257742006D1051&start=10

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Skip,
I have bought several pounds from FAI over the years, but not for a while. I don't remember any problems, and it's what you'll get at most suppliers, and for good reason. Well, ok, sometimes I don't think they put enough ends on the rubber, I use up a few, and I can't find any more for a while. ;-) 

I suspect that, given his level of enthusiasm, combined with some years of experience, George is a good vendor as well.
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billmz:

To be more on topic for the thread, the Born Loser is popular in our club. It was the one design one year. Traditionally, we somehow select a one design that everyone struggles with, but the year we did the Born Loser seemed to be an exception to that rule. 14 grams sounds like a pretty decent weight for a biplane that size.

Al Backstrom, the designer, was also an aeronautical engineer and flying wing enthusiast. He was the creator of the Backstrom Plank and related aircraft. He's got some no cal designs for several flying wings that you can find here:
http://www.b2streamlines.com/Backstrom/

He also has a bunch of more normal designs out there. For instance, there are three others at Outerzone. And I think he published a bunch at the Windy Sock. That newsletter is defunct, but there's an archive of the plans somewhere. I just don't know where.

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billmz
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« Reply #6 on: April 19, 2013, 02:39:35 PM »

Ok, so I finally had a chance to dig through my modeling stuff and found my stash of rubber.  Turns out that I only have about 24" of 1/8" rubber left, but I have a decent supply of  3/16".  The plans call for  2 strands of 1/8", each 20" long.  How much 3/16" rubber should I try in this plane until I can get some more  1/8"?   My intuition tells me that one 20" strand will give me about 75% power, but 2 strands will be too much.

I'll be doing my trimming and flying outdoors since I don't have any place to fly indoors.  Any recommendations will be greatly appreciated!
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
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« Reply #7 on: April 19, 2013, 03:59:54 PM »

Hi Billy.  I may not be reading your post correctly... But for what it is worth:-)   2 strands is one loop.  So if they advise 2 loops of 1/8th, that is the same as one loop of 1/4"   So.... One loop of your 3/16th seems like a great starting point to me anyway.   (One loop 20" long of 3/16th.)   Go easy on the winds at first, to see how the model needs to be trimmed.

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« Reply #8 on: April 19, 2013, 04:19:02 PM »

I agree.  The plans/article do, indeed, state 2 strands (or one loop) of 1/8", but I would recommend 1 loop of 3/16" (2 strands, not 1 strand).  I also agree not to wind to full power until it is very well trimmed.

--george
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billmz
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« Reply #9 on: April 19, 2013, 06:05:49 PM »

I actually found some 1/8" in my Flying Aces Moth.  I had accidentally made that motor just a bit too short, but  it was plenty long enough to make up 2 loops about  9.5" long each after tying the ends.  I will probably start with 1 loop of 3/16" for initial trimming then progess to 2 loops of 1/8" as specified.  I still need to order some 1/8" to make a new motor for my FA Moth and a few peanuts I have which are in need of some fresh rubber, but at least I'll be able to give the Born Loser a try.  Thanks for the advice!
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
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« Reply #10 on: April 19, 2013, 06:16:45 PM »

I am pretty sure the article says "2 strands" of 1/8" rubber.  That is ONE loop.  Personally, I think that might be underpowered.  However, 2 LOOPS would be overpowered.  I think ONE loop (2 strands) of 3/16" would be just about right.

--george
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« Reply #11 on: April 19, 2013, 10:59:10 PM »

Maybe this will help: I corresponded with Al B several years ago about the BL,and I believe he even posted this in another BL build thread---"I had more than enough power from a loop of 1/8" tan SS. I put about 1/3 more turns in for outdoor flying. Basically a 20" loop with 1500 turns indoor and 2000 outdoors."
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billmz
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« Reply #12 on: April 20, 2013, 12:31:12 AM »

I re-read the article and it does say "a 2 strand 1/8" motor about 20" long, and install it doubled."  I interpret that as a strip of rubber 40" long to make a 20" loop, and doubled would equal 4 strands of about 10" each.  I made 2 strands, each 20" long.  Each loop is @ 9.5" long.  Putting both loops in is 4 strands.  Not sure if my interpretation of this is correct, but with 2 loops I have the option of using two loops if I find that one is not enough.

I did get a few trimming flights in this evening at 6pm after the winds died down a bit.  I did make up a loop of 3/16" and put it in.   Put in about 80 turns by hand and got a nice right hand climbing turn about ten feet high and a nice but straight glide for a flight of 10-15 seconds. I will need to add a bit of right rudder to keep it turning after the turns run out.  I also need to address an issue with my freewheeling prop which isn't freewheeling.  My homemade plastic thrust washers are too tight on the prop shaft, not letting shaft move forward and override the catch on the prop.  Because I have a fairly wide bladed prop that wasn't freewheeling, it caused a lot of drag and a subsequent stall when it ran out of turns.  I'll fix it this weekend and give it some more turns and see what happens.  Based on the initial trim flights, I might leave the 3/16" motor in it!
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
billmz
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« Reply #13 on: April 20, 2013, 12:37:15 AM »

I also understand that my shorter loops will limit the amount of turns I can put in it, but based on my rather small field, this is probably a good thing.  Should I gain access to a bigger field, I can add a longer motor.
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
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« Reply #14 on: April 20, 2013, 01:39:52 AM »

Hi Bill
This is probably a bit late but my Born Loser flys indoors on a 15" loop of .140" and is a bit overpowered, I have to keep the turns down to keep it off the ceiling. I think your 3/16 (.187") motor should be OK, just experiment with the length. Good luck they are great flyers.
Dave
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billmz
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« Reply #15 on: April 20, 2013, 10:37:06 AM »

You're not late to the party at all, Dave.  I can use all the data I can get. I appreciate the info you have provided.  I'll probably keep the 3/16" in it for outdoor flying for now, and will try 1/8" if I ever get the chance to try indoor flying. 
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
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« Reply #16 on: April 20, 2013, 04:32:18 PM »

My BL (Tick-Tock) weighs 16.82 grams w/o rubber.  The reference to the doubled loop is for balancing only.  Mine flys very well on the recommended single loop of 1/8th SS, but has to be wound at least 800 turns to get any climb. at 1200, it starts to perk up,but due to my small flying area I have only had the 20" loop to 1500 turns.  The motor should take 1950 without complaining.

I might get brave this summer and put two loops (4strands) of 3/32nd at 20" and wind it tight - just to see what it does.
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Re: Born Loser embryo biplane
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« Reply #17 on: April 20, 2013, 06:16:55 PM »

Hi Bill.  Just to add more info... I noticed on the "Outdoor Embryo" section of this website there is a 8 page thread about the Born Loser bi-plane.  Skip.
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billmz
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« Reply #18 on: April 20, 2013, 11:02:22 PM »

I'll have to go to the outdoor embryo section and see what I can learn from it.  I've already got two 15" loops of 1/8" already made up that I "borrowed" from my FA Moth that i might eventually try in the BL. One at a time, that is...

BTW, my final weight minus rubber is 17.3g, due to the 2.7g of nose weight needed to bring it into proper balance.  I guess the weight of mine seems to compare favorably to others.  I'm looking forward to doing more flying with the BL very soon.
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
billmz
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« Reply #19 on: April 21, 2013, 09:05:39 PM »

Well Sunday evening brought perfect conditions for some trimming flights.  After playing around with elevator trim and a tiny bit more down thrust I've got it climbing very well in nice gentle right hand turns (single 10" loop of 3/16", 300 hand-wound turns for now), but I cannot get this thing to turn in the glide.  It glides beautifully, as long as it's trimmed to glide straight.  As soon as I try to add any right rudder, it goes into a tight spiral in the glide and comes down rather quickly...  not sure how to get this issue resolved. Perhaps I'll try some left rudder and see if that works.  That would be ok for outdoors, but probably wouldn't work out well if I get to fly it indoors.  Any thoughts?  I'm anxious to get the trim finalized so I can crank in some more turns!
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
billmz
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« Reply #20 on: April 22, 2013, 11:08:09 PM »

Ok, so a few trimming flights Monday night in nearly dead-calm air, with left rudder trim, only resulted in a slight yaw to the left under power, and no real left turn in the glide.  On 300 hand-wound turns on the 10" loop of 3/16", it's still climbing in a nice controlled turn to the right to an altitude of about 25-30 feet AGL then transitions into a nice straight glide of 120 feet or so.

I've checked all surfaces for warps, everything is nice and flat.  Dihedral is per the plans, 3/4" per side on both upper and lower wings.  No banana shape in the fuselage either. I just can't figure out how to make this thing turn gently to the right in the glide. I'm running out of ideas.  Anybody else have any thoughts on this?
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
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« Reply #21 on: April 22, 2013, 11:16:21 PM »

Can you incorporate any stab tilt?
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billmz
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« Reply #22 on: April 23, 2013, 01:31:31 AM »

I may be able to do that. The slot for the stab is rather generous as shown on the plans.  I will look at it Tuesday after the chores and honey-do's are done and will try it if it's possible.  As my stab fits in the slot right now, the top surface of it is 1/16" below the top longeron, so there should be a bit of wiggle room to tilt the stab.  I will report on the results...  Thanks for the suggestion!
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Billy

"According to the NTSB investigators, the cause of the crash is still unknown..."
Well DUH!  It was GRAVITY that caused the crash!
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