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Indoor Free Flight Forum => EZB, 35cm, Ministick, AROG, Livingroom Flyers => Topic started by: dslusarc on December 28, 2012, 11:51:36 AM



Title: The sub 400mg EZB plunge!
Post by: dslusarc on December 28, 2012, 11:51:36 AM
I have built many EZBs over the years. Until recently, the lightest I have built was about 450mg back in 2000 that I flew in the USA vs Japan Cat I EZB contest. That model, which I called "Termite" was 14" long (7" body and 7" boom) and did 20:00 in a local 20 foot high gym. Now with all the 300mg EZBs performing well I decided it was time to try one out so here is some photos and comments as I go along this adventure! 


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on December 28, 2012, 12:36:44 PM
The Wing and Stab:

Wing Design:
I decided to follow the latest trend of a symmetrical wing that is glued offset to the motorstick. Typically I would build my models with the inner panel longer with the center rib always at the motorstick/wing post junction. I went with slightly longer tips at 4.25" to match what is currently being used. Spars were from some 4.2# A .026 sheet. Front spar is .060" high and rear is .050" high. Tips are from .025 3.7# A grain cut .045 high. Ribs are from .020" sheet 3.9# and cut about .050" high.

Weight of the two wings uncovered were 66mg and 63mg

Stab:
The stab is a template I have used for a long time. It is 21 sq inches and is 10" span. The shape is not a true ellipse, the tips have been "puffed" to allow less spring back from the wood. Outline was 3.8# .020 x .020 and the ribs are .010" C grain sheet 4#. Weight of both stabs uncovered 12mg each.

Covering:
Here is how I cover (see photos). I roll the Y2K film out on a towel then using a frame made from 1/2 x 1/4' balsa (my frame is 12.5" x 30") I spray the frame with 3M 77 then lay it on top of the film. The film once transferred to the frame billows up ad down a good 2" or do so sags on the frame so it fits airfoils just fin. Before covering I cut the film loose from the ends of the frame so the film is only attached on the two long edges.

Once it is on the frame, I hang the frame off the edge of my workbench then lay the parts to be covered on the film upside down. A diluted solution of 3M77 and naphtha is applied to the outline with a brush. The way to apply is dip the brush in the solution then touch the brush right where the film meets the wood outline. The solution will wick out several inches in each direction from where the brush has touched. The next place you apply the solution will be several inches away so the wicking from the next drop meets the wicking from the previous drop. You apply about every 3 inches or so. It kind of depends on the size of the wood. The stab for instance will wick about 4" per drop but the wing about 3". If you watch you can see he "wicking" take place as the film makes little crinkles as the solution moves. Once the outlines are done, I let it sit about 30 minutes then I flip the frame over and inspect for 100% coverage. Where the film touches the wood you will see the film and balsa imbedded into each other. If there is a bad spot you will see no such joint. I then reapply a drop in that area and let sit another 30 minutes. Once I am happy that I see 100% coverage is cut the parts out with a soldering iron.  

Weights after covering are:
wing1: 86mg
wing2: 89mg
stabs are both 22mg each.

To get the correct dilution of 3M to naphtha I do the following:
Using a small glass bottle (I use a Testors 1/2oz bottle from the local hobby shop), I spray the 3M into the bottle for about 2-3 seconds. I have found that you want to push down barely enough to get the 3M to come out, this way it comes out more like a stream not the fine mist of a full spray. I then wait a few seconds for it to stop bubbling then I fill the glass bottle with naphtha then shake vigorously for about 30 seconds. The solution will be a light milky color. Then to test the solution I dip a piece of left over wood. In this case I used a ~5" long piece of scrap wing spar material. Then I dip the end of it in the solution then immediately put the piece of wood on the Y2K film (near the edge of the frame) then let dry for about 30 minutes. Then I pull it off and see how strong it is. If the wood breaks easily before the film joint then the solution is too strong, add more naphtha. I like it to be about the same strength as the wood. This is a personal preference thing but remember the stronger the solution the more weight you will add when covering. Also stronger solution may need to be used for thicker film. The strength I use for Y2K is too weak for Polymicro, so you may need to mix multiple batches. Having covered with microfilm for years I have an idea of how strong the microfilm to wood bond was so I try to duplicate that bond with my Y2K and 3M solution.

By the way, the process I use to cover is exactly how I cover with microfilm. The only difference is that I use water for joining the wing and film together instead of diluted 3M77 spray. Also when covering a wing with microfilm it is best to attach the wing ribs to the film first then let that dry about 20-30 minutes as the ribs will expand from the water and by letting them dry it helps prevent wing spar waviness.

Don  
  


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on December 28, 2012, 01:35:13 PM
Don,

Great photos and write up.  Is that Y2K or Y2K2 you're using?  The covering and glue on the wing added only 23 mg, so the film is very light. 

Will wait to see more progress.

I'm interested in a plan or photo of your 7-7 model.  What prop and motor did you use for the 20:00 flight ? 

-Kang


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on December 28, 2012, 01:52:36 PM
I do have a plan for it. Looking in my notes I made it in 1996 not 2000. I will post it as soon as I find it. I drew it up on CAD so have the file somewhere. I recall having to launch it on my toes as high as I could reach as the prop flared so much it vibrated/shook and the model would descend for about 1-2 minutes, by then it was about a foot off the floor and if all went well it would climb out of it then go to the ceiling  ;D 


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on December 28, 2012, 01:53:09 PM
By the way it is Y2K2 film.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on December 28, 2012, 02:12:14 PM
I found the Termite plan. Here it is. It is actually a 7"' body and 8" boom. This was made when I use to love to make wing tips by bending over a soldering iron!


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on December 28, 2012, 02:43:17 PM
That is an interesting layout.  A big stab to compensate for the short boom. 

No wing offset.  Is this to fight the tendency of the model to roll right (aka right "wing tuck")?  How much left thrust did you have?  Was there any wash on the wings at rest?

What size motor did you use?  Do you have info on launch torque and turns backed off?

How consistent was the model in flying 20 minutes?  Were there any problems with ceiling bumps turning into dives to the floor?

Thanks for answering the questions!


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on December 28, 2012, 06:33:58 PM
Yes the big tail was to keep tail volume up. The lack of offset was actually to try and make the model intentionally crab/stagger around with the nose up to prevent a fast climb to the ceiling. If I recall correctly it was about 1-2 minutes of staggering around down low to the ground then about 4-5 minutes to get to the ceiling then ceiling bumping until ~15 minutes on the clock then about 5 minutes to come down 20 feet from the ceiling. I came close to setting the Cat I EZB record one day I was at the ceiling at 18 minutes and was BSing with some guys and it drifted a few feet and the wing tip touched the side wall and it slid down the wall. It would have done ~23, I wound for another attempt and the model flew straight for some reason and hit the far wall, I tried to nudge it with the steering pole but then one of the wing struts broke and then the wing failed and the model hit the ground then rolled itself into a ball on the ground in a "death roll".    

The model had about 1/16" opposite wash. I will have to see if I still have notes on the motors used. It would do 18-20 pretty consistently in the gym. Stability was fine during bumping, it is when I added more turns and torque to try for the EZB record is when the "fun" really began. The body was really not strong enough but low ceiling flying typically required stiffer bodies than high ceiling as to keep the rubber weight high you had to use short heavy loops, I think it flew on about .039 x 10" long. My high ceiling EZBs at the time which were heavier flew on longer thinner loops, like 11" of .035, the EZB I did 28:10 with at USIC weighed in at 610mg but used less rubber size than my Cat 1 EZB weighing much less. CAT 1 EZB flying is quite different than high ceiling flying. You basically are flying the model overpowered so it needs a stiffer body. I once took an EZB I had flown in the gym to Akron and wound it the same way. It eventually climbed about 80 feet and deadsticked about 50 feet up.    


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on December 28, 2012, 10:52:07 PM
There's a dearth of information on Cat I EZB flights.  If you can dig up the motor info, that would be great.

Before Coslick set the current Cat I record of 21:44 in 1996, the previous record was 18:40 or so, also set by Coslick in 1995.  Coslick tells me that he only had one other 20+ minute EZB flight of around 20 minutes.

Here is the info on Coslick's Flight

model weight .455 g
motor 8/93 Tan II, .028" x 8" (~ .300 g motor)
1800 turns, backed off 150, launched at 0.1 in-oz
prop ??

Interestingly, Coslick used a shorter, thinner, and lighter motor than your 20 minute flights.

Josh Finn has recently flown a 18:44 flight at the Cat I site, St. Luke's, in Atlanta.

In 1994, in the USA vs. Japan EZB Postal, Satoshi Kinoshita of Kawasaki City flew 20:04 using a .738 g model.

Does anyone know of any other 20+ minute Cat I EZB flights?


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on December 28, 2012, 11:09:43 PM
Don,

That's very clever to induce a crab in the model under high torque.  2 minutes is a long time to do that and adds to the flight time.  4-5 minute climb to the 20' ceiling is very very slow.  I'd be curious how you wound the motor and how much you backed off.

-Kang


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on December 28, 2012, 11:55:04 PM
I wanted to reduce the time the model was bouncing on the ceiling. If you hit the ceiling too soon with too much torque you can break a prop or sometimes the model will fly in larger circles or go straight as the bouncing is so violent so I tried to get the ceiling contact time at a point that was less "violent" so the bumps were more controlled. The site we flew in was a small gym, about 100 x 75 feet so it was easy to get a flight to get out of control on you. In that USA vs Japan contest we flew in, Larry Loucka flew a 17:44 with an EZB weighing about 850mg. His model had a pyramid on the top of the wing center section which we had been trying to help control wing twist.

I am surprised Coslick used such little rubber. I have found that my EZB time suffers with rubber to weight ratios below 1.2 to 1.  I always try to maintain that rubber ratio or greater. I am still digging through my notes to see if I can fly my records from then.  I recall backing off little on those flights and landing with less than half a row of turns. The low backoff is why it was so unpredictable at launch. Sometimes it would climb to the floor and land! The prop flared so much that the blades fluttered, we called it the vibrator prop and it barely pulled which is why I had to launch as high as I could reach, only after the torque fell off and the prop stopped fluttering then it would start to pull.


Title: Re: The sub 400mg EZB plunge!
Post by: Maxout on December 29, 2012, 10:14:51 AM
Sounds like Don's EZB strategy is similar to mine with the exception of the flopping about. It takes me about 45 seconds to get to the ceiling on most flights, with the climb being about 45 degrees nose-up. I suppose this could be remedied with a decent flaring prop, but I haven't had much success with them. The 18:44 flight was made with a narrow blade non-flaring prop. I did make it close to 18 with a flaring one, though. My props turn pretty fast...2800-3000 turns is the norm.

Don, I wish I had some of that Y2K...getting under 300 mg is really a pain with OS (but it can and has been done many times). What stiffness specs are you using for your tail booms?

Can anyone tell me how much success Louka had with his wood cabanes? I've been considering those for some time now as a means of building lighter wings without the wing tuck issues.

-Joshua Finn


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on December 29, 2012, 01:33:26 PM
The pyramid works but can break easily which is why I stopped using it. We made them from .025 x .025 and they extended about 2" on either side of the center post. I use to make a cabane ~5" span about 1.5" high then glue it to the wing at a diagonal. Then once it was dry I glued the other two remaining pieces on to complete the pyramid. We used them back when models were much heavier so they may have been taking more abuse back then than they would now.

Not sure on my tailbooms yet have not cut them out. That is todays work.

The lack of Y2K2 is why I proposed years ago that microfilm be allowed on EZB and Int. Stick as some of us predicted back then that the supply would run out and it would no longer be "commercially available" (as per AMA rules), mainly due to the fact it was an experimental run of film not a production thickness. When Y2K2 first came out it was almost banned because there was no certainty if it would be around years later and consequently would no longer be "commercially available" however it survived the vote of the indoor board so was allowed. So now years later what some of us predicted has unfortunately come true. I was basically tarred and feathered for my proposal to lift the covering restrictions on EZB and Int Stick but I still stand by my reasoning. Those who have the Y2K2 now have an advantage in these events, if microfilm was allowed then you can pour your own "Y2K2" as the weights are nearly identical. In my proposal the weight difference I calculated on an EZB was ~8mg saving with microfilm vs Y2K2. I could not get most people to see the logic of the argument, they simply knee jerked when they saw the word "microfilm" and then personal perceptions of the "difficulty of microfilm" took over and it was voted down. Once it was voted down I then bought 4 rolls of Y2K2 and saved them for only EZB and Int Stick use exclusively.



Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on December 29, 2012, 01:48:29 PM
You save about 15 mg overall using Y2K2 instead of OS film.  May be Don would consider selling a small length of the film for EZB enthusiasts.  I used OS film on my EZB except the ultra light one.   The Y2K2 came from Mark Bennett.  More recently, I received about 5' of Y2K2 from Bob Loeffler, a modeler from Phoenix.  I'm saving it for my HLS.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on December 29, 2012, 04:13:59 PM
Additional Info on Coslick's 21:44 Flight

model weight .455 g
motor 8/93 Tan II, .028" x 8" (~ .300 g motor)
1800 turns, backed off 150, launched at 0.1 in-oz
prop 13.25" D x 23" P






Title: Re: The sub 400mg EZB plunge!
Post by: adanjo on December 29, 2012, 06:30:50 PM
>Does anyone know of any other 20+ minute Cat I EZB flights?

Hi Kang san. I joined this Forum just now.
I have done 25mins 30secs at a 7.4m gym over 10 years ago.
Cat2 flight was 26mins 24secs at a 9m gym.
My ezbs were about 0.5g.
Good flying, Aki


Title: Re: The sub 400mg EZB plunge!
Post by: lincoln on December 29, 2012, 08:32:01 PM
Wow! Thanks for all the good info. I don't fly EZB's these days but maybe I'll get back to it. Meanwhile it's safely (I hope) stored on my hard drive.

I'm afraid I don't  belong in such rarefied company. My best EZB weighed around 0.6g, but it was pretty rigid, or at least the wing was, as I had one little piece of fantastically good wood for the spars.  Best flight was 14:48 at Glastonbury CT, but as I recall it was a no touch that didn't even get up to the retracting barriers that hang from the ceiling around the edge of the central area. Does anyone know how high they are? (Those blue things.) I think it was probably about Cat 1 height or a bit lower. Certainly the ceiling in the middle is much higher.  Wish I could have flown my EZB at a site with a clean ceiling. Or learned how to get my model to climb before it was destroyed. Unfortunately, a careless scale flyer launched into it, and busted it into many pieces. Can't bring myself to build one since then. Maybe if the Weymouth hangar was still there, but they tore it down when I was getting interested in airplanes.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on December 29, 2012, 09:21:54 PM
Hi, Aki,

Those are incredible times.  Do you have information on the motors (length, weight, turns, turns remaining) and the prop?

-Kang



Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on December 30, 2012, 12:44:01 AM
Here is my tailboom and motorstick. The tailboom is from some tapered 3.7# stock I got from F1D biz years ago. My boom is .070 x .060 tapered to .045 x .030 x 9.25" long. I cut two and they both weighed in at 19mg. I put one on deflection gage and with a pin (120mg) deflection is about 0.8 inches.  If I put the actual stab on it it barely deflects as all.

The motorstick is from the thicker side of the 3.7# tapered stock. I am going with a 6" stick. The front is .070 x .134  then middle .083 x .151  then rear .076x .130 . The weight of the blank is 63mg. For the "EZB Challenge" I will be rolling a motorstick from .008" 4# and the blank should be about 30mg. I may roll a tailboom for the challenge as well, I have not decided yet.

Don


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on December 30, 2012, 01:33:43 AM
Looks like the EZB will be very light ...


Title: Re: The sub 400mg EZB plunge!
Post by: adanjo on December 30, 2012, 07:04:33 AM
Hi, Aki,

Those are incredible times.  Do you have information on the motors (length, weight, turns, turns remaining) and the prop?

-Kang


Prop D340 P590

Cat1, 7.4m, '02,Mar,18, 25:30
Tan2 May99, 298mm, 0.59g, 2360-190turns, 9.5gcm, 275

Cat2, 9.0m, '01,Mar,13, 26:24
Tan2 Jul99, 315mm, 0.62g, 2500-180turns, 8.4gcm, 400
It was cold, only 13 degC indoor. So, lots of turns remaining.

These times may be good, but it is not very important.
I could do good times just only because I could fly at very good gyms.
Aki


Title: Re: The sub 400mg EZB plunge!
Post by: Maxout on December 30, 2012, 08:41:11 AM
Don, that is some really good wood. I wish I could even approach those weights. Most of my booms are 35-40 mg and smaller dimensions.

I rigged up a pyramid cabane for my 75 mg EZB wing last night and the results were impressive. I think that will allow me to launch with much higher torque. I'm thinking about making a longer motorstick, but that will have to wait a little.

With your rolled tube fuselage, what do you project the weight will be?


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on December 30, 2012, 01:17:36 PM
My final weight is really going to be dependent on the prop. I was reading my 35cm notes and found a nice 12" prop blade shape I will use on my EZB. I wish EZB had built up props, my 35cm prop was 45mg. I am also actually considering making two new wings.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on December 30, 2012, 02:56:56 PM

Prop D340 P590

Cat1, 7.4m, '02,Mar,18, 25:30
Tan2 May99, 298mm, 0.59g, 2360-190turns, 9.5gcm, 275

Cat2, 9.0m, '01,Mar,13, 26:24
Tan2 Jul99, 315mm, 0.62g, 2500-180turns, 8.4gcm, 400
It was cold, only 13 degC indoor. So, lots of turns remaining.

These times may be good, but it is not very important.
I could do good times just only because I could fly at very good gyms.
Aki

Thank you for the info, Aki.  They are incredible.  Is the Cat I building the same one where you set your F1M and F1L records?

One day, some of us would like to come to Japan and fly with you.

What are your best times in Ministick in these gyms?

-Kang


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on December 30, 2012, 02:58:30 PM
Lincoln,

Why don't you take the EZB challenge and join the fun?  Give it a shot.


Title: Re: The sub 400mg EZB plunge!
Post by: adanjo on December 31, 2012, 06:49:17 AM

Thank you for the info, Aki.  They are incredible.  Is the Cat I building the same one where you set your F1M and F1L records?

One day, some of us would like to come to Japan and fly with you.

What are your best times in Ministick in these gyms?

-Kang
Yes, I set F1L and M records there. And Kinoshita san also flew EZB over 20 mins there.
I have never flown Ministick there.
My best time in Ministick in cat2 9m gym is 11mins 51secs.
The 9m gym is the best one to fly Ministick, though we have to install a ceiling bumper because the ceiling vents catch Ministick.
Aki


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 02, 2013, 05:11:38 PM
Aki,  Your 11:51 Mini Stick flight is also better than the AMA Cat II record, like your EZB flights.  Well done!


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 04, 2013, 12:36:36 AM
Here is my EZB update. Made two fins, covered them and attached to the booms. Each fin was 3mg. Also cut out a second motorstick. I decide I will have two lightweight AMA EZBs then one for the "EZB Challenge" with a rolled body and boom (I found my wood I will be using for that). I also cut out tapered prop spars, enough to make 4 props. Also I separated out all my potential prop wood. I have lots of .007, but have a few .006 sheets and a one that is close to .005" but sure feels lot weaker for that extra .001" thickness difference. I also found some .003-.004 I had specially ground for me years ago by F1D.biz that literally looks like paper it is so thin. I had it ground like that as I once thought about making a built up EZB prop and covering it with this near paper thin balsa so it would be all wood so AMA legal but also hoped it to be more truer in pitch distribution since it would be stiffer. This wood though is so fragile that I think a few bumps would just blow holes into it. Anyhow, I also cut out enough wood for two more wings. I want to try two a little lighter.

After I covered what I had for EZB the other day, there was enough on the frame for a ministick wing and stab.  My last ministick was destroyed years ago when the wire bearing pulled out of the fuselage after I launched so decided now was as good of a time as any to make a new one. so I am building a copy of the one I had years ago and the wing and stab are now built and covered with dihedral added.

Don


Title: Re: The sub 400mg EZB plunge!
Post by: Maxout on January 04, 2013, 08:37:38 AM
This wood though is so fragile that I think a few bumps would just blow holes into it.

Well Don, you could always send that wood to me. ;)


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 05, 2013, 02:43:15 PM
To new wings made. Uncovered they are 45mg and 46mg. Covering them is next. Then onto my wire nose bearings.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 05, 2013, 02:56:17 PM
These are substantially lighter.  Well done!


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 05, 2013, 05:00:02 PM
.008" music wire thrust bearing. ~5mg

Don


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 05, 2013, 05:05:18 PM
These are substantially lighter.  Well done!

Hopefully not substantially weaker as well!


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 06, 2013, 10:24:23 PM
Both motorsticks are finished. 73mg each.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 06, 2013, 11:04:44 PM
Those sticks look pretty strong.  Did you have the tail hook leaning to the left a little? 

It looks like the models will be in the mid 200's.  Very nice.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 06, 2013, 11:14:50 PM
Those sticks look pretty strong.  Did you have the tail hook leaning to the left a little? 
It looks like the models will be in the mid 200's.  Very nice.

Yes hooks leaning to the left. I learned that lesson the hard way many years ago! I think ~250mg is a reasonable projection. It really will come down to these props. I never had good luck with superthin wood EZB props in the past, the blades would get wavy on me. So need to come up with something other that they way I use to make EZB props.

Do you know what Richmonds EZB weighed that he set the Cat II record at Kent with?


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 07, 2013, 05:06:19 PM
Yes hooks leaning to the left. I learned that lesson the hard way many years ago! I think ~250mg is a reasonable projection. It really will come down to these props. I never had good luck with superthin wood EZB props in the past, the blades would get wavy on me. So need to come up with something other that they way I use to make EZB props.

Do you know what Richmonds EZB weighed that he set the Cat II record at Kent with?

Richmond's EZB was approximately 305 mg at Kent.

I make my prop blades in the usual way (a la Coslick's Hobby Shop EZB article).  This method works well for me.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 10, 2013, 11:44:08 PM
OK, the two new wings are covered. Both are ~65mg. I think these may be too weak but hard to say as I have no real reference to what they need to be. These wings also have 5 ribs in them. I may put the pyramid on these wings if needed. Props are next!

Don


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 11, 2013, 12:11:45 AM
That's what my wing weighs so it's on track. 

You could test glide the wing with the fuselage ballasted with the right weights and see how it handles the load.

My EZB flies slower than a F1D.  Sanborn's F1D passed my EZB when we flew in Atlanta last month.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 11, 2013, 12:26:39 AM
Well them maybe all will be OK. All in all I am pleased with how these new EZBs are turning out. Not sure on prop size, was thinking of a 12" diameter 24" pitch flaring shape. I tried a 10/20 once years ago on a light EZB and the prop was very light for the time about 65mg but rpm was rather high so went back to 14" and it flew better but then that model was ~500mg. I was thinking of trying a 10" but with over 2:1 P/D. My ministick prop is a 7/17 prop which is 2.4:1 so why not a 10/24 for EZB?


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 11, 2013, 03:37:56 AM
My prop was 11.75 x 23, symmetric blade, for Cat IV and 11.75 x 19, moderately flaring blade, for Cat I with scrubbing.   For no touch Cat I or II, I would think 12x24 full flaring would be good.  I have a 13.25 x 26 full flaring prop that I would like to try in a low ceiling site.

Have fun experimenting!


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 17, 2013, 07:50:45 PM
Sorry for the lack of updates. I have been getting my butt kicked by the latest flu bug going around. Just getting over it now. Hope to get back to these props over the weekend.

Don


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 19, 2013, 04:37:24 PM
Here is my first prop. Seems I do not have the lightest wood for the blades. The blades are 66mg for the pair. 81mg with spar wood. This will be a 12/24 prop. 


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 19, 2013, 08:22:43 PM
Yes, 66 mg for a small prop is heavy.  Do you have another sheet of similar thickness and density?  If so, I would like to know what is the weight of the sheet divided by its area -- a figure in mg / in^2 (or mg/si).

The lightest wood that I have used is just under 5 mg/si.  My 11.75" props have ~4 si per blade.  My total weight budget is something like:

blades x 2                 40 mg
spar x 2                    18 mg
glue (blades to spars)   2 mg
hook                          3 mg
total                        63 mg

I have some of this light wood if you would like a sheet.

-kang



Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 19, 2013, 08:52:19 PM
That is good info. My blades are 4.63 sq inches each and .005" thick so that comes out to 5.4# wood. The sheet was not marked for weight so I will try other sheets. This wood calculates to 7.13 mg/sq inch so I am guessing your 5mg/sq inch wood is ~.005" 3.8# density?

Don
 


Title: Re: The sub 400mg EZB plunge!
Post by: green-man on January 20, 2013, 03:52:55 AM
Hi Don,

It's very difficult (but not impossible) to cut these ultra-thin sheets without surface compression from the spinning blade increasing the density of the finished sheet.

Nick.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 20, 2013, 12:46:06 PM
Another thing is to try a blade with slightly smaller area.  Richmond's prop is only about 3.5 si, and so was Max Zaluska's.   Both had narrow chord blades.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 20, 2013, 02:28:46 PM
Nick: I have heard that surface grinding and cutting thin sheets can compress the wood. Maybe that is the case on this sheet. 

Kang: 3.5 sq inches may make these blades usable after all! Is there a plan for Jims prop anywhere? What was his diameter and pitch? 

Don


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 20, 2013, 03:16:59 PM
Don,

I copied Richmond's prop for my "BS 6" EZB.  A plan is available in the Builder's Plan Gallery.

His prop is 13 3/8" x 30" -- a rather "large" and high pitch prop.  Probably a little too "big" for the 250 mg EZB.  I have mine pitched lower, around 24 to 26", but  I think the true pitch during flight is much higher than that, as the blades flare significantly.  I haven't used this prop, yet, for the ultra light EZB, but I would like to try when the opportunity is there.

-kang


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 21, 2013, 12:00:01 AM
All the .005-.006" wood I have comes out to about 6.5 mg sq inch. I did find one sheet of .007 C that weighs  6.5 mg/sq inch so if I can sand it down a little that might work. My new blade design is 3.5 sq inches so now I am looking at ~46 mg or so for a pair of blades.  I also finished my blade form today, I added some fiberglass cloth to the back side of it to keep the twist and to make it stiff so I am now ready to form some blades. I have to also figure out how much to dilute the wood glue used for attaching the blades onto the spar. I have never used thinned out wood glue to attach prop blades before, I guess I will start with a 50/50 glue to water mix  ???

Don


Title: Re: The sub 400mg EZB plunge!
Post by: Olbill on January 21, 2013, 12:11:24 AM
I don't like wood glue for my F1L blades. The last couple I made I just used tiny spots of thinned Duco. When I had to redo them to replace the spars, it was easy to get them off the old spars with acetone. Of course my models are Mack trucks compared to EZBs this light.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 21, 2013, 01:07:53 AM
I don't dilute wood glue because it's hard to pick up a *teeny* drop when the glue is sopping wet.  Wood glue in its original viscosity is easy to pick up, in very small amounts, with end of a 007 or 008" music wire.  A big blob of diluted glue is the last thing you want -- it's going to be heavy.

Applying a small drop of glue takes work, because you have to place it exactly where the wood is touching -- and no more.  You might want to practice a little before gluing down the real prop. 



Title: Re: The sub 400mg EZB plunge!
Post by: albisko on January 22, 2013, 03:45:48 AM
hi,
my first attempt for EZB light prop.
blade 0,2mm C-grain


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 22, 2013, 10:23:27 PM
Those props are very nicely done.  Show us photos of your EZB, too.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 22, 2013, 11:44:00 PM
I am finding these super light EZB props a pain to work with. I have one blade on and drying. I had to thin the wood glue a little mainly because it was getting a skin on it in a matter of ~60 seconds so had to thin it so I could apply it. I will have blade #2 ready to put on tomorrow. These props are taking way too much time to make. I think I am going to start on my F1L structure and work on these props a little bite at a time due to the long delays needed between steps. These EZB props are not like the old days when I would bake them on a form in the over then have the blades glued on the spar and finished within 30 minutes. Hope these are worth the effort going into them! EZB was so much easier when a "light" one was 500-600 mg!


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 22, 2013, 11:51:30 PM
I don't like wood glue for my F1L blades. The last couple I made I just used tiny spots of thinned Duco. When I had to redo them to replace the spars, it was easy to get them off the old spars with acetone. Of course my models are Mack trucks compared to EZBs this light.

Bill,

I normally use Duco for props as well but I do know from my past experience trying when using this thin .005" thick wood the blades would twist or distort as it dried. So I would add plasticizer to the glue to stop that but then I had to double glue the joints as the pasticizer slowed the dry time so much that glue soaked into the spar wood on the first application. So maybe the wood glue will work OK for me. I think I recall Jerry Nolin using white glue on his "Serendipity" EZB props.   


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 23, 2013, 12:54:56 AM
Well I was going to wait until tomorrow but the first blade looked so good after I took it off the block that I decided to get the second one on before heading to bed. This time I again used the thinned wood glue but did glue dots about 3/8" apart down the spar then put the blade on. The other one I did the tip, root and middle, then went back and added glue in between after it dried. This is all locations at once since I have more work time on the thinned glue. Will weigh it tomorrow.

Don


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 23, 2013, 02:04:12 AM
No complaining allowed when you're going down to 250 mg for the model.  This is not an easy to build 350 mg EZB !

In the end, I think you'll be happy that you went the extra length to minimize glue usage on the prop.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 23, 2013, 07:18:17 AM
Just took the prop off the block and weighed it. I get 74mg. Not too bad since these blades were about 50mg for the pair. The next one should be a little lighter since they are from lighter blade material. So my weight projection is:

wing: 65mg
stab: 22mg
boom w/fin: 22mg
stick: 73mg
prop: 74mg
Total= 256mg plus wing post and tissue tube weight needs to be added.

Don


Title: Re: The sub 400mg EZB plunge!
Post by: albisko on January 23, 2013, 09:52:50 AM
Those props are very nicely done.  Show us photos of your EZB, too.

the rest of the model is under construction
:)


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 23, 2013, 10:56:52 AM

wing: 65mg
stab: 22mg
boom w/fin: 22mg
stick: 73mg
prop: 74mg
Total= 256mg plus wing post and tissue tube weight needs to be added.

Don

Well done.  Welcome to the 250 mg EZB club !

When will you get a chance to fly it?  Perhaps some test flights in the living room can be made.



Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 24, 2013, 12:44:04 AM
I should be able to test fly Tuesday next week. I ran the weights and numbers through the spreadsheet and I get a CG of about .07" forward of the trailing edge (about 97%) which required a short nose length of only about .5". I hope the prop does not get caught under the wing.   

Don


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 24, 2013, 01:35:07 AM
FYI -- I have my nose at 1", CG .27" in front of TE, and 17% SSM. 


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 24, 2013, 01:49:15 AM
I think a little extra SSM is good for a flexible model.

Also, I remember that I have had the 65 mg prop tuck under the wing  a couple of times: once on a 330 mg model and another on the ultra light one.  Both have the nose at 1".


Title: Re: The sub 400mg EZB plunge!
Post by: albisko on January 24, 2013, 03:48:20 AM
Blades after shaping and cutting.


Title: Re: The sub 400mg EZB plunge!
Post by: Wout Moerman on January 24, 2013, 06:04:28 AM
I love the colour of the blades. Is it just the ink you used to draw the outline?


Title: Re: The sub 400mg EZB plunge!
Post by: albisko on January 24, 2013, 06:40:57 AM
I love the colour of the blades. Is it just the ink you used to draw the outline?

I use food colors dissolved in water.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 29, 2013, 01:20:11 AM
Spent today rolling some tissue tubes. I rolled some .032", .039" and .047". I plan on either using the .032 or .039 for the EZB. I also have the tail booms glued to the bodies now so just need to get the tubes and posts on. I laid out the model to see how it is going to look, see photo below. Wont be able to test fly tomorrow though, so will have to shoot for next Tuesday evening.

Don


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 29, 2013, 10:49:14 PM
I originally intended to save weight by not using wing posts nor tissue tubes.  I ended up using very short wing posts, and only one tissue tube for the front wing post.  I glue the rear wing post in place at the flying site and remove it to put the wing back in the box.  I will put a second tube on in the near future. The tube ID is .047".


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 29, 2013, 10:54:59 PM
My model at Lakehurst:

https://picasaweb.google.com/108052131825905862674/Indoor?authkey=Gv1sRgCKHGy8us3vTxJw#5795630470249402450

At home with a smaller, lighter prop:

https://picasaweb.google.com/108052131825905862674/Indoor?authkey=Gv1sRgCKHGy8us3vTxJw#5767286610287325698


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 04, 2013, 01:12:18 AM
Well it is ~260-265mg, hard to tell the scale bounces around with the model sitting on the scale. I test flew it in the house and I am amazed these tiny wing spars hold up so well. I used a 8" loop weighing 235mg with 800 turns and it was climbing and I was able to see how it handled bumping my ceiling. Seems as stable as my other EZBs. I am not sure how much opposite wash it will need. Right now the wing has none. But need to test fly in the gym to see how it handles once I add more torque. Usually I need about 3/32" opposite wash in an EZB.   


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 04, 2013, 02:01:37 AM
It looks really nice.  Total flying weight is only around ~500 mg, so the wing can be substantially weaker than a 500 mg EZB with a flying weight of 1 g.

I think you will really enjoy flying it.


Title: Re: The sub 400mg EZB plunge!
Post by: Wout Moerman on February 04, 2013, 04:52:28 AM
What do you mean with "opposite wash in an EZB"? Is that wash out?


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 04, 2013, 07:19:04 AM
Opposite wash means the wash in is in the outer wing instead of the inner wing (when at rest). The reason it is done is because the motor stick twists when the motor is attached and causes the outerwing to have washout. Too much washout can make the wing tuck in at launch. By adding opposite wash in, when the motor is attached, the outer wing goes flat (the wash in in disappears) and wash in appears on the inner wing from the motorstick twist. So opposite wash means wash in on the opposite wing.

Don    


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 04, 2013, 12:47:13 PM
Don,

My guess is that you won't need much "opposite wash", if any.   Your motor stick is stout for this size of model.  My model has a very small amount of opposite wash at rest (less than my other EZB's), but my motor stick is about 10 mg lighter than yours.  Of course, it all depends on the amount of torque you want to launch the model.   You should be able to launch at a higher torque than mine.

-Kang


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 07, 2013, 09:42:17 PM
Don, did you have a flying session, yet?


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 07, 2013, 11:02:36 PM
There was one this past Tuesday but I forgot my brother was giving his first lecture at the local Audobon Society that night so went to support him. However, I am geared up for this upcoming Tuesday. So will be cutting some rubber this weekend and making up some motors and half motor sticks.

Don 


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 07, 2013, 11:29:54 PM
I see that your brother is a birdwatcher.  So am I!  Any other birders in the family?


Title: Re: The sub 400mg EZB plunge!
Post by: Tsova on February 08, 2013, 12:31:43 PM
Don,    Do you have weekly flying sessions? At Andrews?


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 08, 2013, 12:49:24 PM
I see that your brother is a birdwatcher.  So am I!  Any other birders in the family?

Big time into birds and airliners actually. Here is his facebook page you can see some of his photos:
http://www.facebook.com/chuck.slusarczyk/photos_stream

Here is his airliner website:
http://www.opshots.net/


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 08, 2013, 12:51:55 PM
Don,    Do you have weekly flying sessions? At Andrews?

Weekly indoor RC session at a gym on Tuesday nights from 6:30 to 9:30pm but they have a second gym the size of the small Andrews gym that we can have for ourselves. There are only about 10 people in this club and they will pause to let an indoor model fly in the main gym. 

Don


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 11, 2013, 11:12:34 PM
EZB is in the box ready for test flying tomorrow night. I made up some half motors tonight. Will let you know how it goes.

Don


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 12, 2013, 08:02:26 PM
No flying today. Got to the gym and a musical rehearsal was starting, so went to the side gym and was filled with chairs and the air system blowing. Will try again next week :-(


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 12, 2013, 09:16:06 PM
Oh NO!  Still, the wait will be worth it ...


Title: Re: The sub 400mg EZB plunge!
Post by: Olbill on February 12, 2013, 09:24:28 PM
I feel your pain Don. I've had many similar experiences.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 12, 2013, 10:19:35 PM
I think this means this EZB will fly well! Usually a plane that has roadblocks thrown in my way will always fly the best :-)  So I am working on covering my F1L tonight instead.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 21, 2013, 02:41:12 AM
Any updates, Don?


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 21, 2013, 07:52:12 AM
No, school was closed Tuesday for teacher service day or something similar. The good news is that we may have found a new Cat 1 indoor site. The church my parents go to has a fairly nice sized gym and the ceiling is smooth tile in the center up until about 6 feet from the wall. I have never seen a gym like this before, it is like a typical open girder gym then they decided to install a flat ceiling over most of the ceiling, the ceiling stops about 6 feet around in all four sides. I suspect there will be easier access to this site so I am quite hopeful!

Don


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 21, 2013, 11:57:18 PM
That's great to hear.  Any chance it would be available Saturday night before the Kent contest :) ?


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 26, 2013, 11:13:11 PM
Test flew the EZB today. Did one half motor flight that went up about 15 feet did ~7:30 then wound a few extra turn in it as my goal for the day was 10 minute half motor no touch and I overdid it a little, I did find the model will need a little opposite wash. It started to tuck some and I decided to let it keep going as it was slowly going down and I though it would pull out after a few laps but the prop hit the floor and after a few hits to the ground one prop spar broke. It is an easy fix and I will add a little opposite wash to the wing. I do think this wing is a little too weak though, it flexes more than I like and I still have the slightly heavier wing I initially built that I will try and see if there is a flight time difference. The inboard leading edge spar seems to be the one causing issues. Perhaps I should have used a tapered wing spar. I took some video, it is uploading to youtube now.

Don

    


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 26, 2013, 11:46:56 PM
The first video did not get processed correctly so uploaded again. Here is the new link:

http://youtu.be/WtxHLm_xcu0


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 27, 2013, 02:00:37 AM
Nice video.  It seems to fly really well.  Slow and steady.

The center span of the wing looks good, but the tips look to be deflected up a lot, although I don't know how they look at rest.  Because the wing tips are usually really wimpy, I make sure that the first 1/2" to 3/4" of the tips are strong enough.  My LE is .023" thick, 6.1# wood, tapered from .040" in the center to .030" at the dihedral.  My tip is .015" thick, 5.7# tapered from .035" to .025".

As you say, the opposite wash should do the trick to combat the tucking.

What's the prop diameter?


Title: Re: The sub 400mg EZB plunge!
Post by: _shadow_ on February 27, 2013, 09:04:33 PM
The first video did not get processed correctly so uploaded again. Here is the new link:

http://youtu.be/WtxHLm_xcu0

Nice video....is that speed slower than F1D?

Regards


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 27, 2013, 10:27:22 PM
The wing does flex too much in my opinion. I have added some struts on this wing to see if it will be salvageable. But a new wing is already in process of being built. Prop is 12" diameter and has been repaired.   


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 27, 2013, 10:28:41 PM
Quote
Nice video....is that speed slower than F1D?

Seems pretty close!


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 27, 2013, 11:34:06 PM
The 250 mg EZB should be slightly slower than a F1D.  Sanborn's F1D passed my EZB in the air when we flew in Atlanta back in December.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 28, 2013, 10:47:47 PM
Framed up two new wings today. Hope to get them covered tomorrow. Then back to the F1D build.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on March 01, 2013, 01:21:30 AM
I had built two ultra light wings, but my cat, I believe, destroyed the first one.  Luckily, he destroyed the "heavy" one.  The only thing left is a wing tip that is now the rudder on my F1D.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 01, 2013, 01:30:16 AM
My 1st microfilm model ever (I was about 14 years old) and I had just finished it and started to put it into a box as it was late at night. Just then our cat came by and jumped into the box as I still had the lid open as I was getting ready to put the prop in the box. Smashed it all into bits in about 2 seconds.

Don


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 03, 2013, 06:40:26 PM
New wing is covered and now just adding in the dihedral. This wing is VERY stiff and is 30mg heavier but that is fine with me. I will still have a 300mg EZB.


Title: Re: The sub 400mg EZB plunge!
Post by: albisko on March 03, 2013, 08:06:19 PM
New wing is covered and now just adding in the dihedral.
How to make a dihedral "cut"?


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 03, 2013, 08:24:10 PM
When I glue the wing together the tips are made from a separate piece of wood. I glue them together with minimal glue then after it is covered, I use a razor and cut the joint loose then reglue with the dihedral added. This time I make a stronger glue joint than before. 


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 05, 2013, 12:10:32 AM
I got the second EZB wing covered tonight. Needs to have dihedral added. But now time for bed! Here is a photo of the EZB wings next to my new F1D parts.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 07, 2013, 09:13:46 PM
My new razor plane came yesterday, so I started messing with it and planed me a bunch of .005-.008" thick sheet. Need to do some fine tuning to the razor plane to get more of the .005" thick more consistently but this is a slick way to get EZB prop wood! This photo is of the planed sheets which I dipped in hot water then placed on a glass board to dry. Most of the sheets are about 18" long and 1" wide.

Don  


Title: Re: The sub 400mg EZB plunge!
Post by: jakepF1D on March 08, 2013, 02:49:51 PM
This is interesting.  I have a 1920's Stanley #4 plane that I'm planning to restore.  It would be neat to plane some of my own prop sheet wood.  Where did you get the block you're planing?


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 08, 2013, 04:49:46 PM
Some SIG contest grade wood I already had from years ago.


Title: Re: The sub 400mg EZB plunge!
Post by: Dave Andreski on March 08, 2013, 04:55:34 PM
Don, Which razor plane did you buy?
Thanks,
Dave


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 08, 2013, 04:57:24 PM
This one.

http://www.skykingrcproducts.com/accessories/david/david_razor_plane.html


Title: Re: The sub 400mg EZB plunge!
Post by: Dave Andreski on March 08, 2013, 05:00:47 PM
Thanks Don.
I have one of those from a different source. Great tool.
Dave


Title: Re: The sub 400mg EZB plunge!
Post by: hastf1b on March 09, 2013, 10:01:18 AM
The "David's" are very good. I use my for over 30 years.
I always make different strengths then I can work without change.

Heinz


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 11, 2013, 12:45:15 AM
First photos is sawn cut blades next to shaved blades. The shaved blades are 60mg for the pair, which is not too bad. Just need some lighter wood stock to shave from but for some left over pieces of contest grade wood they are not too bad. The other photo is a block I found at the local hobbyshop this weekend, density is 3.6# so I will shave some prop wood off this block for sure. The wood was actually Midwest balsa. The hobby shop I was at just got a shipment or Midwest wood. I ended up getting about 10 sheets in the 4-5 pound range. Spent probably 45 minutes weighting all the wood they had, but it was worth it. 


Title: Re: The sub 400mg EZB plunge!
Post by: albisko on March 11, 2013, 05:36:46 AM
my EZB continue....
wing (dry) 120mg
tail (dry) 30mg

more photos in picasa
https://plus.google.com/photos/100588849894345200054/albums?banner=pwa&gpsrc=pwrd1#photos/100588849894345200054/albums/5853993337028154529


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 12, 2013, 07:48:02 AM
Albisko, Keep up the good work!

I got to do more test flying yesterday and the new wing is super stiff. Almost excessively stiff but I did some tests and the model does not tuck or dive in when bumping the ceiling etc so it is a very good wing for any type of ceiling bumping. The bad news is that the prop I have simply sucks. It flares way too much either the blade is too much of a flare design or the spar is simply too weak. The prop cruises well but when torque is added the blades flare so much the model struggles to climb, I can barely get it to climb 15 feet on a half motor and once the prop settles down it cruises well. It acts like a VP prop stuck in high pitch too long. So I have cut some new spars from stiffer wood and also will glue the next set of blades on a with the spar a little more forward. 


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 12, 2013, 11:33:20 PM
Stripped some .020 x .020 4# balsa and glued to the spar to stiffen it. Props is much stronger now. Only added ~5 mg to the prop. I have a new set of blades for my new prop forming now.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on March 13, 2013, 02:41:53 AM
It's hard to know if a very light flaring prop will work until you fly it.  Then you know.  I am a little conservative when it comes to prop spars, and I'm always amazed how light Larry Coslick's prop spars are.   You can get away with wimpier spars on a symmetric, non-flaring prop, but not as easily on a full-flaring prop.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 18, 2013, 01:19:13 AM
My new prop is finished. The weight is 82mg but the spar is very stiff, perhaps too stiff but at least I now have a better idea of what it will probably need. The spar with hook was 32 mg compared to my old prop spar and hook were around 20mg. The reality of what I need is somewhere in the middle I think.  Test flying at the gym tomorrow evening. I will say an 300mg EZB compared to a 260mg is a world of difference in stiffness. This 300mg model will take bumps and keeps on going. The lighter version in my opinion most likely would not tolerate such activities. I think the lightest models may be best suited for big wide open sites where the chances of ceiling bumping and steering are minimal. 


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 18, 2013, 11:39:44 PM
Great day of test flying. The new prop is much better. I took out my half motor only put in 750 winds and it climbed up 18 feet and did about 8 minutes and this motor will take ~1200 turns so I was quite happy, it may be overpowered a little actually on this motor. This prop may best suited for USIC than Kent so will make a new prop to try and flare a little more now that I know what "too stiff" a spar is. Having gym flying session really helps iron these kinds of details out.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on March 19, 2013, 01:07:33 AM
Coslick will bring his Cat II record model to Kent this year.   There will be some very light EZB's there. 


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on March 31, 2013, 11:32:47 PM
Found a sub 4# piece of C sheet so I planed some wood off of it. So here are a set of blades for my new EZB prop, this pair is 40 mg and the new spar is about 20 mg so hoping for about 65mg finished. The good thing with this planing is that a sheet of 1/16" x 1" wide and about 12 " long has yielded me enough wood for about 8 more props. 


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on April 01, 2013, 12:53:05 AM
That wood looks very nice.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on April 01, 2013, 07:49:40 AM
Yes and it planed very well. The sheet I got it from was SIG contest grade 3" x 36" x 1/16" C grain sheet and the average weight of the sheet was 5# but the middle portion of the sheet was lighter when I held it up to the light. So I cut out the lighter section and it was around 3.7# density, the rest of the sheet around 6#. The 3.7# block I found at my local hobyshop is pretty much useless. I can not plane thinner than ~.010" or the wood crumbles like cork. So I then cut some strips for possible motor sticks or tailbooms but the wood is very weak like a noodle so I kind of gave up on that block so went back through my SIG wood shipment and found this light piece and I got nearly 100% success rate from planing pass. With this lighter prop and if I were to build a new wing less than 100 mg I will be back at 250 mg pretty easy. So I may build one more new model after Kent.


Title: Re: The sub 400mg EZB plunge!
Post by: green-man on April 01, 2013, 08:10:03 AM
Hi Don,

Do you happen to know if the 3.7 lb model shop block was from Ecuador or PNG? If it was very white, it was probably from PNG.

Nick.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on April 01, 2013, 12:49:14 PM
The corky block from the model shop that I cannot shave is very white (almost lookslike it was bleached white) and from Midwest Balsa. Not sure where Midwest gets their wood from but much of the Midwest light wood I bought is white but this block is very white. The sheet I got these current EZB blades from is from Sig Mfg, and is a more brown/tan color., in fact all the wood I get from Sig is more brown and tan instead of white. Now some of the best wood I received from True Weight back about 10 years ago was whiter in color but now some of this whiter stuff seems weaker and "mushy". I would be interested in what experiences you have found. 


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on April 02, 2013, 11:03:46 PM
New prop is finished. Weight is 66mg, I am happy  :D


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 23, 2016, 10:41:05 PM
Starting a new EZB. I am shooting for 250mg or less :) yes lots of ribs but they serve a purpose. It reduces the unsupported length of the spar to help column strength.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on January 23, 2016, 11:02:34 PM
Don,

Start another thread called "the sub 250 mg EZB dunk!"

-Kang


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on January 23, 2016, 11:23:34 PM
Indeed! These are tiny wood sizes. I have your "Donna's Dragonfly" info for my guide. Herd is my stick and boom. Sucking blank 5.5" and 49mg, boom is 8" and 19mg. I am making this on a little shorter.


Title: Re: The sub 400mg EZB plunge!
Post by: Chris-DC5 on January 26, 2016, 03:56:09 PM
I love looking and reading about these fantastic light models,

I have managed to get my F1L models to the 1.2g limit but would love to have a go at a sub 1g EZB soon.

Thanks

Chris.


Title: Re: The sub 400mg EZB plunge!
Post by: cglynn on January 27, 2016, 10:35:09 AM
Chris, sub 1g EZB is very doable.  If you haven't already done so, access the Hobby Shopper EZB article by Larry Coslick--http://www.indoorduration.com/INAVHobbyShopper.htm -- and faithfully follow the directions.  Build all of the jigs (the deflection jig will serve you for years to come) and use his wood sizes and weights.  Doing so will get you a 6-700mg EZB that will fly really, really well.  Best of all, true to its title, you can build a good EZB from hobby shop wood.  That said, if you have some nice indoor .008" C grain, it would be good for the prop.  If not, find a nice piece of 1mm and sand it down as per this article-- http://www.indoorduration.com/INAVEasyEZBProps.htm --

Build a few hobby shoppers and then check out Coslick's Micro B-- http://www.indoorduration.com/ftp/MicroBEZB.pdf --to build one under 500mg.  

Hope that helps, and have fun

Chris G


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 02, 2016, 12:24:52 AM
Getting closer to completion. Projected weight looks to be about 225 mg. This will be my only EZB at this weight I will try to build as these are simply ridiculous to make and not sure if worth the effort. Will see how it flies.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 05, 2016, 11:39:09 PM
All finished. 229 mg. Will test fly next weekend.


Title: Re: The sub 400mg EZB plunge!
Post by: Olbill on February 06, 2016, 12:28:32 AM
Impressive! I hope it does well.


Title: Re: The sub 400mg EZB plunge!
Post by: cglynn on February 06, 2016, 11:14:09 AM
Don, that is unreal.  Very nice work.  Looking forward to seeing that one fly.

CG


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 06, 2016, 11:37:20 AM
Here's DDF at Lakehurst Labor Day weekend 2012 after its maiden flight.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 06, 2016, 02:05:40 PM
I am really curious as if the wing is strong enough, at first I thought no but is seems the correct strength in proportion to the rest of it. I got a little sloppy with my white glue glue on the prop blades and probably could have saved 5 mg but I am just going to leave it for now. I want to see if in the Cat I gym if is has an obvious gain over my 320 mg model. The 320 g model can bump around and recover with no wing tucking. Not sure on this one. This was probably one of the hardest planes to build I have done in some time.


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 06, 2016, 03:33:17 PM
I made one Cat I flight under the 22' ceiling in Atlanta in 2012. It was something like 21:20. I had to back off on the torque because when the model dove, the flaring prop would tuck (I used a different prop) under the wing. Otherwise, the model recovered very well. It has 17% SSM.

I think my model can bang moderately around the ceiling without much worry. In Atlanta, the problem was that the model would hit the wall of the ceiling "recess" about 3' above the lower ceiling and crawl down the wall nose down. Once it cleared the wall, it would accelerate nose down before recovering, unless the prop tucked.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 06, 2016, 04:39:14 PM
Good info to know. I went with 16% margin so essentially the same.


Title: Re: The sub 400mg EZB plunge!
Post by: adanjo on February 07, 2016, 03:13:54 AM
(deleted by Aki, sorry)


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 15, 2016, 07:43:36 PM
Well did some test flying yesterday. I was rather pleased. The wing is stronger than I thought but somehow I messed up my inner wing spars and they bow noticeably up near the tip than the other wing spars. I think I may have made an error in cutting them not compensating for the longer inner wingspan. I wound it up a little and it climbed out nicely. I am thinking of taking it to west Baden next month to air it out a little. I am also going to try one more wing to try and fix the bowing I have on the inner spars, the LE and TE both bow equally but it looks odd and I want to fix it. Watching this one fly I think a 200 mg EZB is doable. I may try one more extreme complete model to try and break the 200 mg barrier as I have some real good 3.2# motor stick and boom wood. I took some flight video and am in process of downloading if off my cell phone.     


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 15, 2016, 11:56:09 PM
Here is the video:
https://www.youtube.com/watch?v=A46IeleytTw

I just cut all the wood for "Absurdi-B" Mk 2

Don


Title: Re: The sub 400mg EZB plunge!
Post by: ykleetx on February 16, 2016, 12:07:13 AM
That model flies incredibly well. I'm glad you're going for the 200 mg barrier.

-Kang


Title: Re: The sub 400mg EZB plunge!
Post by: Olbill on February 16, 2016, 12:33:43 AM
That's beautiful Don!


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 16, 2016, 09:12:20 PM
Thanks guys. I have the new wing currently under construction on the bench right now. When this one is done I will have four EZBs, two in the 320 range, one at 228, and one at whatever this one comes out as. Hopefully one will do good for me.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 16, 2016, 10:33:01 PM
New wing under construction.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 16, 2016, 11:35:09 PM
Razor planed some 3.2# wood for my new prop.


Title: Re: The sub 400mg EZB plunge!
Post by: adanjo on February 17, 2016, 12:06:22 AM
New wing under construction.

Is the toothpick a glue applicator?

Aki


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 17, 2016, 12:37:18 AM
Aki,

I use a thin wire for glue application. The tooth pick is for lifting the ribs up to the top of the wing spar before gluing.

Don


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 17, 2016, 01:12:56 AM
Stab under construction.


Title: Re: The sub 400mg EZB plunge!
Post by: green-man on February 17, 2016, 06:44:43 PM
Razor planed some 3.2# wood for my new prop.

Hi Don. Have you found any noticeable density increase by compression of the blade with the planed wood?


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 17, 2016, 09:31:05 PM
Not that I am aware of. I do soak the wood in water after planing to flatten it out so that may undo any compression. I can check these two sheets.   


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 17, 2016, 11:28:41 PM
Breaking 200 mg will be very tough. My new parts on the scale give an approximate finished weight of 214mg. If only I could use microfilm :-) I may settle for under 220mg instead.


Title: Re: The sub 400mg EZB plunge!
Post by: dslusarc on February 18, 2016, 12:17:20 AM
 Nick,

Just checked density, I get about 3-3.2# so same as marked on the sheet. I just can not get thinner than .007" on real light wood when planing. So I try to lightly sand to .005 ish.


Title: Re: The sub 400mg EZB plunge!
Post by: green-man on February 20, 2016, 10:26:26 AM
Nick,

Just checked density, I get about 3-3.2# so same as marked on the sheet. I just can not get thinner than .007" on real light wood when planing. So I try to lightly sand to .005 ish.

Interesting - Thanks Don.


Title: Re: The sub 400mg EZB plunge!
Post by: leop on March 22, 2016, 03:34:22 AM
At 1:00pm EDT, Monday, March 21, 2016, the body of Don's deceased Ultralight EZB was retrieved after it’s crash landing on the second atrium column clockwise from the Mineral Springs West Baden Hotel entrance.  It appears that the initial weekend rescue efforts caused severe trauma and the subsequent death.  The autopsy has listed the cause of death to be a severely broken main wing, a missing stab, a broken tail boom, and the traumatic amputation of both prop blades.  Any of these would have alone proved fatal.  The high-lift team was able to retrieve many of the body parts and all are being kept for transplant to other EZB’s to be built.  The body was transported to the Bloomington airplane funeral home and balsa repository.  Future visitation and services await the decision of the EZB’s immediate family.
 
The retrieval team worked diligently to recover four other planes that crashed or had forced landings in the same atrium area.  All four were found alive with differing amounts and types of injury.  All are at the Bloomington airplane hospital and workshop awaiting transport to rehabilitation facilities or their homes.  One plane, the F1L, was found to have wandered from its initial hard landing location but the retrieval searchers found it in the upper dome area somewhat downhill from the initial landing site.  The F1L was not injured and there are plans for it to fly again in a few weeks.  The two LPP’s that had crashed into the crown moldings were each retrieved with some non-life threatening injuries.  A second EZB was found on a balcony near the initial search area just clockwise from where the deceased EZB was found.  That EZB suffered a severally broken stab that appears to require a complete amputation and replacement.
 
The search and rescue team work above and beyond the call of duty.  One team member, Tony, deserves special mention for his deft handling of all the rescued planes.  Jim, the team leader, showed great skill in navigating the high lift rescue equipment in sometimes tight confines.

With our condolences,
 
LeoP