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.020 size GLH

Old 12-02-2013, 10:41 AM
  #51  
lfinney
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the old red backplate cox needle valve assemblies were 128 tpi, the kirn kraft is a brass block with nva pressed in
Old 12-02-2013, 04:43 PM
  #52  
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" I wish they made a Galbreath head for the 020 "
Doug does a modification to burnt out 020 glow heads to take Nelson globee plugs -: http://www.the-printer.net/DookCat.html
Old 12-03-2013, 09:23 AM
  #53  
hllywdb
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OK, got a little slowed up on the GLH over the holidays. Had to repair the daughter's car after an "In-flight mishap" going 70mph BACKWARDS. Hey, mom taught her to drive.

For those with a keen eye, yes that is Ultracote arctic white. Took 8 rolls, that's why I don't do giant scale. Used K&B epoxy kote on the bumpers and trimcote on the door handles. Anyway, that's how my Thanksgiving weekend went.

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Old 12-03-2013, 10:29 AM
  #54  
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Back to the GLH. I got the wings built (perhaps over-built) but it allows for less than perfect landings. Here is my plan at this point. I am going to finish it and install the stock TD 020 and get the plane flying and trimmed out. This will be the control group.

Then I will proceed with the modifications as follows:

Scott (WINANS) from earlier in the thread really came through for me with another TD and a few spare parts at a very reasonable price. THANKS SCOTT!

I have ordered up some parts like venturis, aluminum intake, and a spare case, NVAs etc....

I am taking MJD's advice and have ordered some small hub 1/2a Combat CF props with a 70mm pitch from the Ukraine to cut down.

I am going with CP's idea of tapping the case for pressure. I am thinking left side of the case????

I am also going to lighten the piston up a bit. Not sure yet on trimming the skirt. Anyone tried that on a 020 yet?

I figure the crank should be fine with a polish and hand lap. I've filled and "Scooped" the intake port on TD cranks before, but not real convinced of an appreciable difference. I figure a good TD 049 crank holds up pretty well in the 23k range. They will do more but lifespan starts to die off and I haven't found any spare cranks yet. But since the TD 010 will spin all day at 30k, probably due to the reduced reciprocating weight, I am going to guess the 020 may be safe in the 27k realm?

I have been looking for a small remote NVA with 128 threads as aspeed suggested, but have not had any luck yet. So as plan B I am going to try the 049 TD venturi and Texas Timer NVA. My thought is to start with 2 of them and fill in the center. Then I can open each one up a tweak at a time. I figure I can just re-drill the 3 holes for the fuel each at 020 size. If I alternate between the 2, drilling each one out larger, when I reach the point of diminished returns I will have the other one setup at max already. Of course this is not an exact science as the prop size will also effect best venturi size as well. So I will be shaving props at the same time. I am assuming I will need to try some of the props on the control motor as well just to make sure it still flies with the smaller diameter props.

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Old 12-03-2013, 11:00 AM
  #55  
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It looks great and very small...

What size did you decide on, 16" or 18" wingspan?
I did a bit of the math and just scaling with the engine size would give: 32"x(0.020/0.049)^1/3 ≈ 24" ?
Or is the GLH too slow at 32" on a .049 engine?
Old 12-03-2013, 11:40 AM
  #56  
hllywdb
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Thanks Mr Cox

Or is the GLH too slow at 32" on a .049 engine?
Well........ CP would probably argue that a GLH with a 12" wing and a Cyclone is a little pokey for him, but I scaled my 1/2a GLH down to 28" with a 1/4" thick wing and used a AME 061 with some mods on it. I'm happy with the way it flys so I ended up dropping to 16" on this one for the TD 020. My thinking was that the Wee Stick is around 20" so 16" seemed good for a GLH in that size.

Last edited by hllywdb; 12-03-2013 at 11:42 AM.
Old 12-03-2013, 12:39 PM
  #57  
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Yes, I agree that 27-28" is a better size for .049 engines, I just think that less than 20" sounds a little small for a peewee. What wing area will you get approximately?
Q200 for .049 is a little large (if one is not competing), and something around 160-170 inch squared works well, even for .061 Norvels.
There was a Q100 for the .020 engines I believe, but I've never flown anything below 100 square inch on a .020 engine...
Old 12-03-2013, 01:12 PM
  #58  
hllywdb
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The wee stick is a tad under 100 inches. This one is closer to 60. But my 1/2a GLH is right around 150, but also heavier. My wee stick is around 5.5oz so if this comes in under 5 my wing loading is still way down around 12oz per sq ft
Old 12-03-2013, 02:00 PM
  #59  
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I want to go to Florida again, it looks warm. I should try some Monocote on the bottom 1/4 panels of my van. I replaced them 8 years ago, and they are gone again. I thought I would put a pic of the Kirnkraft remote to get an idea. It looks pretty simple to make from any needle valve really. Just have to put in some aluminum or stainless wire in the hole so it doesn't plug up when soldering. Oh, it is 3/32" not 1/16" like I thought. I will edit that.
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Old 12-03-2013, 04:59 PM
  #60  
hllywdb
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I would go with one of the iron on fabrics for the rockers. It's stronger and also goes with that Avalanche look that seems to be so popular. I think we may be onto something with the Ultra cote, but let's see how it works out on CP's Ranchero. The Sebring was easy, lots of curves, the Ranchero has lots of corners and I suck at those. On the other hand he will save a fortune on chrome by using aluminium monokote on the bumpers! I just sent out a springer front end, a sissy bar, and a chain gaurd and it was $1500.
Old 12-03-2013, 07:30 PM
  #61  
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I spotted a 3x2.5 3-blade Cox prop at the LHS today, so I snagged it since I never had one before. It's a homely little thing with bell bottom blades. I think it is actually stiffer than the 1/2A black props, relatively speaking. I could be all wrong, but I have a hard time believing it is a terribly efficient prop.

But what I found encouraging was that the hub on this thing is very similar in size to the hub on the fg combat prop I trimmed. Weight is similar too. It might work well.
Old 12-03-2013, 07:46 PM
  #62  
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All of the Cox 3 blade props I have used were low on efficiency. The only ones that made sense were the 3 blade pusher props. So I went with your advice and ordered some small hub thin blade CF combat props from the Ukraine.
Old 12-03-2013, 07:55 PM
  #63  
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Well, I hope they work okay. I just don't know of any other props other than electric props that are remotely in the range you need. It will be interesting to see how low in diameter you need to go to get the rpm back up with the additional pitch. I wish I had a TD .020 to try out the prop I have, just some neglected PeeWees.
Old 12-03-2013, 07:57 PM
  #64  
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Aspeed that looks like they soldered the tube into an aluminum block and then pressed the NVA into it. How come CP is the only one that likes my idea of the 1150 Dominator on the motor? If I fill in the hole a bit the rest of the venturi just acts like a big velocity stack. Put a couple of Moroso and Holley stickers on the vertical stab and call it a day.
Old 12-04-2013, 01:34 AM
  #65  
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Originally Posted by hllywdb View Post
The wee stick is a tad under 100 inches. This one is closer to 60. But my 1/2a GLH is right around 150, but also heavier. My wee stick is around 5.5oz so if this comes in under 5 my wing loading is still way down around 12oz per sq ft
That's a pretty small plane then, should be fast...

It sounds like a little odd scaling to me though, it is not the wingloading in oz/sq feet that is important but rather the "cubic wingloading" that should be scaled.
When the engine size is changed by a factor 0.020/0.049 ≈ 0.41, it means that the length scale should only change by a factor (0.41)^1/3 ≈ 0.74.
The wing area is then changed by 0.74^2 ≈ 0.55, i.e. the wing area would go down to about 82-110 inch^2- (from 150-200 for a .049 size).

I don't think that I have flow anything much below 100 inch^2 on a .020, but perhaps 60 inch^2 will be fine, it should certainly be small enough.
Old 12-04-2013, 06:52 AM
  #66  
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The Dominator sounds good to me. I think the KK needle is machined out of 3/16" sq.brass completely and the tubing soldered onto that. I have a pic of a snorkel I made as a kid for the TD .049 to use a remote. It had a tight fitting cowl and made removing the top easier without losing the needle setting on a 1/2A control line speed plane. I think I made a big venturi for it too, but it is gone over the years. It is just 1/4 - 32 thread on the .049. I would imagine the .020 could be drilled out to just a bit smaller than the collector ring size if you want to go faster. A collector ring groove could be machined on the inside of the needle valve assembly so the hole could be drilled even bigger if a new venturi is made. You would then only be limited to the minor dia. size of the thread. We used to go to .125" on the .049, but I have noticed the Fora is a full .250", so they must have found it possible to go huge. I don't have an .020 to measure or play with for comparison unfortunately.
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Old 12-04-2013, 08:33 AM
  #67  
hllywdb
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Hi Mr Cox,
Rather than use a bunch of number crunching I relied on the tried and true "Looks about right" engineering methodology first employed by Evil Kinevil in some of his early motorcycle jumps. This later evolved into the "Hold my beer I'm gonna try something" methodology used in early Monster truck competition, but I digress....

Anyway, in the first shot you can see my daughter's Jr Falcon, which is a spirited flyer on 4 channels and a big mig 061 (at least compared to my early 2 channel baby bee version). It spins a 5.7X3 prop around 18k. My 28" GLH spins a 4" pitch prop at about 10k higher and is lots of fun to fly.

In the next shot you see my Pee Wee powered stick next to the current project. Once I had the wing assembled and tips on it's closer to 18" span. With a 3 1/2" cord that puts me at 64 sq in of wing area. Sounds small but looks right. So I am hoping the results will turn out closer to the "Looks about right" method rather than the "Hold my Beer I'm gonna try something" method.

aspeed given the fora at .250 the stock TD 049 at around .089??? might be just about right. I'm not worried about suction as I will be using pressure and I don't have to worry about transitions so I am thinking bigger is better. But it's easy to fill it in and work my way up.

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Old 12-04-2013, 09:40 AM
  #68  
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Nothing wrong with what looks right, trial and error is all part of the fun.
Old 12-04-2013, 10:22 AM
  #69  
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You might find that a ball point pen cartridge or something similar is a push in fit inside the TD venturi.
Even a hunk of lead poured in, piece of wood dowel, etc.
Whatever it takes to get the 128 thread NVA idea going. To make fooling around with these ideas easier to accomplish Harbor Freight sells numbered drill indexes for very low prices.
Hllywdb...I've found that the best sanding tool for the Ranchero's concave "character lines" is a wooly paint roller with self adhesive sandpaper stuck to it. Summit sells rolls fairly cheap of 80, 180, 320 and 400 dry type paper to bring a project all the way through the priming phases and ready for top coat.

I asked them why they don't sell heavier than 80 and they said that a lot of shops prohibit the use of anything heavier because they found more time got spent repairing the deep scratches even though it seems like more progress is made with the heavier grits.
This notion is still controversial with "old Timers" on the discussion boards.

I doubt you would need to "re-jet" the .049 NVA is the .020 is propped for high rpm.
To shave that tiny piston, I would make an aluminum collar with a lengthwise slit that will hold the piston firmly. The "Poor Man's Lathe" idea with a drill motor strapped to a work table on it's side is all you need for power. Use a length of twine or wire to tie off the con rod to keep it from flopping around. Rig up a steady tool rest next to the piston for the back of your Xacto blade.
The shaving process takes very little pressure and I do it dry. Angle to blade so that it is not "attacking" the piston, angle it so that it is scraping the lead-loy piston material. Use a slow speed and make sure that the drill motor is firmly clamped down if you aren't using a lathe.
It's probably good to have a magnifying glass handy to inspect your progress. I've gone almost as thin as an index card on .049 pistons and never had one fail or get distorted.
Every microgram adds up at 30,000 rpm, so figure on how much SPI you can get away with and shorten the skirt before you get started with thinning the skirt.
Old 12-04-2013, 01:26 PM
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Good idea of doing the skirt 1st before wasting time on the lightening. I was going to try the dremel on the lightening but I will try the exacto/Black&Decker lathe first.

The old timers are correct, using 36 or 40 grit (by hand) will get you closer to straight much faster. Most newbies go to a finer grit too early and that's why they get so many "waves" on the pannels. In my body box you will also find a wood working cheese grater that I use while the mud is still drying. Cuts a lot of time. As far as getting rid of the heavey scratches, I use a product called "Icing" which is nice thin easy sanding mud. Back in the day we always had multiple cans going and you would use the stuff in the bottom of the can to get roughed out and use the top of a new can for finer stuff. Icing saves that step. I also use it for spot putty as it doesn't shrink like nitrostan.

Any thoughts on using 6 gram servers at this size? I'm thinking about it just for space on the wing as 1/4" thick isn't much to work with.
Old 12-04-2013, 01:42 PM
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By the way I also used your method of aileron torque rods that I picked up off one of your SWR threads a while back. Where you make the rods without using tubes, cut the slot, grease up the wire good and drop it into the wet epoxy which makes a perfectly sized bushing for it. Not only less slop but an absolute must on thin wings like this where the tubes on most linkage kits are thicker than the TE.

The pen idea may work but I am trying to stay away from a spray bar in the middle. Then I would need to go that much larger to account for it and I have only so much room to hog out the intake at this size.
Old 12-04-2013, 05:33 PM
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The smallest wing I ever built for .049 power was 105 sq inches. The plane didn't have much glide at about 10-11 ozs but it was definitely able to safely land. Your plane will be much lighter. You can cut the wing out completely to get your aileron servo buried as deep as possible. I've also seen the aileron servo laid flat with crazy looking pushrods to connect to the torque rods. You've got to be militant about weight, but I don't know anything about choosing servos this small. Go with the smallest ones you dare use and don't spend a lot of time making the plane look too pretty.
The plastic sleeve in the venturi ought to still let you have the needle off to the side. I think Dickeybird had an informational thread about inserting a sleeve in a TD .049 venturi, [to make it run better on suction] but I can't remember if he had to machine a sleeve [on a drill press], or if he found a common household item to do it.
Old 12-04-2013, 06:05 PM
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I hollowed the wing all the way down to the top skin. I'm thinking of just hot glueing a 6g servo in rather than try and use hardwood mounts. Also going to just use hing tape as control surfaces are 1/16". I figure I can also go light on the elevator pushrod as it's setup to pull for "up" and I won't be doing a lot of inverted.
Old 12-04-2013, 07:06 PM
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I've used Shoe Goop to mount servos [.40 sized plane] on balsa that was smeered with CA to toughen it. The plane crashed on the first flight too........no, just kidding.
Yes, good idea to use a fine music wire for the elevator and thread it through a couple of supports. "
Pull for UP" should be made the law of the land.
The push rod has to be supported / stiff enough not to allow the elevator to vibrate your micro servo to death, so it pays to manually test the install before calling it good..
In my entire "hobby life" I've never used wood push rods...ever. I suppose you could carefully select 1/8" x 1/8" hard balsa and go through all the gyrations to affix wire ends to it, but the idea of using wood has always given me THE CREEPS.
Old 12-04-2013, 08:41 PM
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The only planes I've used balsa pushrods on were my Sig Kadets. Never had a problem but they were 3/8 square. Not worried too much about flutter on this as it's only going (yaawwnn) 60mph. What makes it fun is that it's something the size of a flip flop going 60mph. Come to think of it if my ex wife had got her shoes going 60mph I would probably have a concussion or brain damage.

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