Time to finish a model

Looking good.

Under 200g (7 oz) should fly just fine, lighter is still better.

Phil

That black and red is beautiful. And feather light, it should be a quick little plane.

pkrankow wrote:Looking good.

Under 200g (7 oz) should fly just fine, lighter is still better.

Phil

Ok so is 200g the magic number then as my last simple sheeted came in at 180g without engine tank etc flew but only good for roundy roundy really am hoping a bit more for this maybe a loop and some invert maybe ?
I think I may be flogging a dead horse though as I'm still running .012 cable think I gain a lot of drag with that !!!

Thanks rusty does look pretty, I think I made the right choice, with this one less is definitely more ! just a Sticker on inboard wing and she's a good'n
The only thing that's gonna let MeDown is my heavy lines

Balance is very important if you want maneuverability. 6 oz is about all the thrust you get off a Cox motor.

http://personal.osi.hu/fuzesisz/strc_eng/index.htm
plug in 5x3, standard prop,2 blades, 15000 rpm, 68F

I am working on a test stand that can measure actual force using a scale, I am not convinced the thrust is that low for all the prop/engine configurations.

I expect a Cox engine to pull my 2 meter glider to height and it weighs quite a bit.

I just weighed in the airplanes on my desk.

My jumping bean is 165 grams (5.8 oz), engine and all. It is a hot performer now that it is balanced. It has an older 2 bypass no boost open port Cox motor on it. I just switched it to a stunt tank from a baby bee tank, so I expect better performance out of it.

I built a pair of Zingers that I just weighed in at 215g and 220g with engine (I don't have an engine on either so I used the one from the Jumping Bean, since it is off the airplane.) I am rather concerned about their weight, but they have large wings and large control surfaces. I have not flown either yet, the engine for one was at the tach race.

I also have a 1/2A Sig Skyray that has the motor pinned on for balancing that weighs in at 185g. The control surface is tiny so I expect it to be zippy but not so maneuverable. I have not flown it yet.

I run 10lb Powerpro spectra lines. I used to fly on Dacron.

Phil

Sorry my mistake was reading the scales wrong
Overall weight so far without fuel is 124g a little bit better !!

I like it!

Can you take a close up pic of the cowl?

Just for you ...

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Made up of solid balsa planed and sanded to shape of engine mount then painted gives impression of being full bodies fus !!! " alt="" />

And more ..." alt="" />

It really does! Good job!

Thanks for the pics.

Ron

Maybe I missed it. What engine are you using?

RknRusty wrote:Maybe I missed it. What engine are you using?

I made the assumption (bad on my part, I know) he is using a bee of some type because it is a bulkhead mount on a solid profile airplane.

That is a good question though.

Phil

Here you can see the bulkhead clearly ..." alt="" />

And for those of you wondering this is the power train so far
#2 barrell
Postage stamp backplate modded to sit flush
Nva mod with fuel tube to stop that pesky hunting syndrome !!
Kap pak 1/2oz tank
Treating her to a new gasket
But can't decide .... Mylar or Teflon Reed had good results with both
What do u think ?
Also two head gaskets as use 25% N


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What's that prop Phill is it a 6 3 or 4?
If it's a 6x4 it ain't gonna blow a gale
Anyway. See The thrustometer in Dirks
Thread. You could always Texaco it.
Stick 3 gaskets in and stick an 8 4 up front
Mine chugged along at around 6/6500k.
It wouldn't have enough to pull the skin off a
Rice pudding. I performed pretty much the
Same experiment on my Christmas Bee.

Hey John it's a 5x4 had pretty good results ...ish
But seems to scream don't know why had better results with Mylar on a 5" and Teflon on a 6" or maybe it's just me ????

Dwe know what the rpm's were?

On that prop 16k= 7oz this is the funny part 60.6 mph flying speed

This is my most run engine normally get between 18-19700k steady depending on which fuel ...20/25% guess its well run in as it's nothing special but the fine thread backplate helps needling !! Used to run copper reeds usually got 16-17k on a 5x4
I agree top speed is funny I think the figures aren't taking prop slip into account !!

Ran the same engine fuel combo last year with a muffler on and Rpm's went down by 2k !!!! Bit quieter but real power loss really noticeable even without tacho sound was hunting but nva wasn't moving when put On a tacho was seeing anything between 14-16k ran like a bag of poo just my experience tis all would like to run with muffler some times esp down local park but can't deal with the inconsistent running what am I doing wrong am not running it with spi so should run ok no ?

How do you figure your SPI? I use a lamp and hold the engine up as I s-l-o-w-l-y crank it through either without a head or so the piston can leak down and at TDC if I can see light through the exhaust it has SPI. I have only 1 engine that doesn't have SPI, even my single bypass baby bee has SPI via this method.

Phil

This is correct if the bottom of the piston climbs higher than the bottom of the port then it has spi I have 3 timing shims to raise the head when I use the muffler as they seem to run worse with a muffler and spi for normal running I get best results with my smallest of shims decreasing the induction by about 1 thou obviously this would slightly decrease the compression slightly but not noticeably I would not think when running normally it has spi just slightly less than standard

If there is a "standard" ?
Thinking about it by theory it should run slower with less spi so adding a shim which decreases the intake volume should have a negative effect on the Rpm's I think but then again if you add a shim your also changing timing effectively just can't remember which way advance or retard