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Old Feb 17, 2012, 09:42 PM
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DerekB's Avatar
Cape Coral, FL
Joined Nov 2001
1,910 Posts
Quote:
Originally Posted by bamaguy View Post
At over $100....that is way too pricey! I think the system from Dimension Engineering runs a bit less????
Oh, I agree. I was just throwin' it out there as an option, since I happen to come across it.

I'm thinking Dimension is the way to go and it's fully programmable. That's what I ordered. $60 for the starter kit: programmer w/ USB cable; controller; 4 LED's. Then just buy the $30 controller plus LED's for another airplane.

Spyro said be sure to get LED's that are bright enough. He made a custom controller, so can probably supply whatever power he needed / decided? The Flytron LED's he used, appears like they are made to strobe only.

I don't know how to evaluate the specs of LED's. For example,

Dimension's LEDs specs for red, green and white - 15 lumens, 1/2 watt, 150mA max.
Spyro said these are not bright enough.
I read that white has much higher lumens than red or green for the same power.

I ordered an assortment of 5mm "bare" LED's from DIYRC.com (mcd = milli candela)
White 5mm - 40,000 mcd, Vf = 3.0.3.4 volts @ 20mA
Green 5mm - 18,000 mcd, Vf = 3.4-3.6 volts @ 20mA
Red 5mm - 18,000 mcd, Vf = 2.0-2.4 volts @ 20mA

The LED's suggested by Spyro from eBay (but he did not use on his 737)
White - 1 watt, 100 lumen
Green - 1 watt, 50 lumen
Red - 1 watt, 70 lumen
And the 30 degree clear lense converter (to focus the light)

LED's from lazertoyz:
white 55,000 mcd at 25 degree angle
red 25,000 mcd at 25 degree angle
green 25,000 mcd at 25 degree angle
They also have some focusing lenses for mounting, but I can't find at the moment.


How to compare??? I don't know.

Definitions (our friend wikipedia): (units: cd = candela, lm = lumen, sr = steradian)
Lumen - luminous flux (cd-sr) : a measure of the total "amount" of visible light emitted by a source. The lumen is defined as 1 lm = 1cd-sr (1 lumen equals 1 candela-steradian) A steradian is a solid angle.
Candela - luminous intensity (lm/sr) : the power emitted by a light source over a given solid angle (ie, how much of the sphere is the light shining into).

This example helps: A 25 Watt flourescent light bulb puts out around 1700 lumens. If that light is radiated equally in all directions (that is, over a full sphere which has a solid angle of 4 Pi steradians) , it will have an intensity of around 135 candela. If focused into a 20 degree beam, it will have an intensity of around 18,000 candela.

So, I am thinking it's important to "focus" the light energy of the LED, especially landing lights. Sure, you won't see "all of them" at the same time from a distance. But the ones pointing at your will be bright.

It sounds more fair if LED's are rated in Lumens - total amount of light emitted - since the Candela rating depends on how you focus that available light. Thus, there is no way to compare the "brightness" of one LED rated at 15 lumens to another rated at 40,000 mcd, unless they also specify the angle with the mcd.

Then there's the issue of adding the proper resistor - that's another session.

After all that brain numbing information, I think we are back to "Try It And Fly It".

I actually learned a lot doing that research .
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Old Feb 17, 2012, 10:52 PM
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Low Show's Avatar
United States, NC, Wilmington
Joined Jul 2004
304 Posts
Derek check out this guy's stuff, he has one led set up so that it pulses off and on slowly like a rotating becon, cool and cheap. And thats why we roll...Don

www.wix.com/dianneanddavid/daves-r-c
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Old Feb 18, 2012, 07:52 PM
WIFE HAND LAUNCHED MY PLANES!
Spyro37's Avatar
Joined Jun 2009
2,297 Posts
Quote:
Originally Posted by DerekB View Post

Spyro said be sure to get LED's that are bright enough. He made a custom controller, so can probably supply whatever power he needed / decided? The Flytron LED's he used, appears like they are made to strobe only.



What I used are:
- http://www.flytron.com/rc-light-syst...light-red.html
- http://www.flytron.com/102-1w-green-...rc-lights.html
- http://www.flytron.com/rc-light-syst...rc-lights.html
- http://www.flytron.com/82-60-lens-for-powerleds.html - Diffuser bay (carved foam) lined with chrome tape (see my video) OR find the same diffuser that ALREADY HAS A MIRROR CHROME REFLECTOR on the diffuser itself, just like a regular flashlight's refector.


Then there's the issue of adding the proper resistor - that's another session.



- I did lots or hours on resistor values bench testing, such as current draw, generated heat, brightness output, & LED "burn-in" test.
33ohm, 1/2WATT resistor PER 1WATT LED (any color) is the BEST value to use. If you want to be more "conservative" 47 ohm will give you a very close brightness result. Values I provided is enough to get away from using LED STAR heat sink, with uncompromised brightness & not burning the 1W LED
Resistor value is based on a 5V LED power source.


eBAY links I recommended are for those guys who wants to save some few dollars, and might be beneficial for others or other future projects that you guys may have, but quality may not (or may) be the same.



I actually learned a lot doing that research .

HERE IS MY NAV LIGHT SCHEMATIC/DESIGN (as posted by Hoeni) FOR BETTER UNDERSTANDING:


http://www.rc-network.de/forum/showt...737-700/page23
(Please click translate to ENGLISH)

- Spyro
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Old Feb 19, 2012, 02:23 AM
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DerekB's Avatar
Cape Coral, FL
Joined Nov 2001
1,910 Posts
Quote:
Originally Posted by Spyro37 View Post

HERE IS MY NAV LIGHT SCHEMATIC/DESIGN (as posted by Hoeni) FOR BETTER UNDERSTANDING:


http://www.rc-network.de/forum/showt...737-700/page23
(Please click translate to ENGLISH)

- Spyro
Spyro - More great information. Thank you. I have lots of studying to do. On the other forum, I guess you are Honi? (I don't know how to make the 2 dots over the o).

My motors arrived today, the Hobby King L2855-2300kv outrunner. I'm trying this first with the Change Sun 10 blade 70mm fan just because it's the cheapest. For $13, I could not resist. Guys over on the CS 10 blade thread are liking this motor on 4S and can push to 5S. I have 4S packs already that I want to use.

I made an EDF test stand, but have to go back to Home Depot tomorrow cuz I misjudged the length of a few bolts and need to get replacements. It never fails - it's not possible to make only one trip to Home Depot. I'll post some photos and test results tomorrow when I get it all running.
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Old Feb 19, 2012, 08:31 AM
ich bauen groß modell flugzeug
Keenan smith's Avatar
United Kingdom, London
Joined Dec 2010
6,855 Posts
sounds cool


keenan

http://nutsaboutrc.freeforums.org/in...da968271e9907e
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Old Feb 19, 2012, 12:02 PM
TAFTS
Chandler, AZ
Joined Apr 2008
352 Posts
I don't post much but I always get some good info from RCG so I thought it was time I shared a little. Here is my 737. It was given to me. Backing up a little... My good friend Mike gave it to our mutual friend Elvis as a Birthday gift and as part of a product demo. Elvis built it and had Mike fly it. On the second flight, this happened:

Elvis 737 unplanned landing.mp4 (0 min 22 sec)


Elvis re-built it and flew it once, somewhat successfully. He had problems with the gear and it just didn't fly well. He really only flies in a park and also decided it was too much for him in a park environment. They mutually decided to give it to me as I am a somewhat more experienced modeler than either of them and I always like the challenge of 'fixing' models that don't work well.

I stripped most of the electronics to the foam. I replaced some of the servos and re-worked all the linkages. I tuned up the landing gear and replaced all the wires with 1/8 music wire. I replaced the nacelle mounts with 1/4 ply as the old ones were broken up and crooked from the crash.

I reversed the nose gear for aesthetics and to make it stronger. The mounts were broken and needed surgery anyways. I know its not scale but the average spectator won't know that and they certainly won't see the wheels hanging out now. I replaced and beefed up all the landing gear plates. I tend to hand my transmitter around a lot so I like the gear to be extra strong for when someone pounds it in.

I added flaps. I put magnets on the lower nacelle covers to make engine servicing easier. I can replace a motor or fan or entire assembly in a matter of minutes. Murphy's law says I will never need to since I spent the time to make it easier

The wing was in pretty rough shape. I added a 1/4 carbon tube to each side to stiffen them up a bit. I sprayed the entire wing with some primer gray that I had. Its a slightly different color but presentable. The dark blue on the nose was Testor's Model Master Blue Angel Blue or FS15050 spray can.

I have 6 flights on it with about 15 landings. Some of the landings were NOT greasers and the new wire is holding up well with no signs of bending like the old ones did. The flaps are fun to play with. Takeoff is shortened with the take-off setting (about 10 degrees). Landings approaches are steeper. The controls are all solid with the re-worked linkages and better servos.

I don't know what the fans and motors are. They came from a project of Mikes. I think he said they were in an F-14 ARF he had. I fly it on a pair of 4S 3300 packs. Its fun to fly and certainly draws attention at the field.

I would like to thank Mike and Elvis for the generous gift. I suppose they are more the beneficiary as they still get to fly it when ever they want and someone else maintains, transports, and stores it for them

Scott
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Old Feb 19, 2012, 12:17 PM
6 months to finish a rtf
pulsery2k1's Avatar
upstate ny
Joined Jun 2003
1,862 Posts
Scott Todd

Instresting video , Looks like the model got to slow then the steep
turn (stall speed increase's in a bank) and stalled an when in .
good luck ,and thanks for shareing
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Old Feb 19, 2012, 12:44 PM
ich bauen groß modell flugzeug
Keenan smith's Avatar
United Kingdom, London
Joined Dec 2010
6,855 Posts
^ditto!
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Old Feb 19, 2012, 01:32 PM
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DerekB's Avatar
Cape Coral, FL
Joined Nov 2001
1,910 Posts
Quote:
Originally Posted by Scott Todd View Post
On the second flight, this happened:
Ouch, that was painful to watch . Either it tip stalled, or simply wrong aileron correction and just rolled it in. Or a combo. He was heading somewhat toward himself, and depending on your experience, it's easy to get crossed up on the ailerons. You have to be absolutely instinctive and have zero percent "wrong way" corrections at that altitude. I remember when I was learning, if I put the "wrong" aileron correction, and it did not correct, I would instinctively give it more cuz I didn't know it was "wrong". It took me a long time to "know" it was wrong, then make the opposite correction. It took even longer to simply never get it wrong (knock on balsa, never say never).

It's great to know the plane can take a terrible beating like that and get rebuilt to look good and fly another day, versus the trash can.

You did a great job restoring.
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Old Feb 19, 2012, 02:54 PM
ich bauen groß modell flugzeug
Keenan smith's Avatar
United Kingdom, London
Joined Dec 2010
6,855 Posts
your gonna need an inbd flap other wise shes gonna be a tip stallin Devil!
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Old Feb 19, 2012, 06:34 PM
TAFTS
Chandler, AZ
Joined Apr 2008
352 Posts
It didn't have flaps when it crashed. He just got too slow. He's used to flying airplanes this size that weigh 3 pounds. He later said he totally felt the elevator stick getting too far back and just didn't have time to correct it. It was way slower than it should have been on the approach.
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Old Feb 20, 2012, 04:15 PM
Vollietollie
Joined Feb 2012
4 Posts
Thanks for fast answering,

I have 6 servo's wiches 2 for ailerons, 2 for elevator, 1 for rudder and 1 for nose wheelsteering.
The manifacturer told me to use Y connector to the ailerons, Y connector for the ESC and 1 x 3 Y connector for the retracts. Now I have 6x extension cables, I used 2 extension cables for two ailerons, 2 extension cables for two elevator.

Question:
Using 1 extension cable for the nose wheel and 1 for nose wheel steering?

Im trying to get aileron and nose wheel Y-harnass, so its working at same time and same direction. What I understand is that doesn't matter wich channel using?
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Old Feb 20, 2012, 04:49 PM
*** gravity sucks ***
Fotor's Avatar
Netherlands
Joined Mar 2007
399 Posts
I would couple the nosewheel steering to the rudder. If you couple the nosewheel steering to the ailerons you will have troubles taking off in crosswind.
For example: you have crosswind from the left. Because the vertical tail will act as a wind vane the nose will want to veer to the left, into the wind. To counteract that you will need right rudder and right nosewheel. At the same time you'll have to give a bit of left aileron, because the crosswind will want to bank the airplane to the right. You're flying 'cross-controls' at this point, rudder and aileron go in opposite directions. If you give right aileron with the crosswind from the left (because you coupled the nosewheel steering to the ailerons, you will need right nosewheel steering) there is a chance that your airplane will strike the right wingtip to the ground.

Crosswind takeoff are quite a handful with this model anyway, I did quite some and had some scary situations. I don't fly this plane no more with more than a few knots from the side.
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Old Feb 20, 2012, 09:21 PM
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NickM91's Avatar
Australia, WA, Perth
Joined Jan 2009
250 Posts
Quote:
Originally Posted by k.smith459 View Post
your gonna need an inbd flap other wise shes gonna be a stallin Devil!
Generally flaps lead to less desirable stall characteristics, as in you're more likely to drop a wing than without. It depends on a lot of variables though
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Old Feb 21, 2012, 11:39 PM
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Doug W's Avatar
United States, WA, Seattle
Joined Jul 2010
488 Posts
Quote:
Originally Posted by NickM91 View Post
Generally flaps lead to less desirable stall characteristics, as in you're more likely to drop a wing than without. It depends on a lot of variables though
Where on earth is your data coming from on stalls with flaps vs.without in the sense of dropping a wing? Flaps by design create higher lift and a lower stall speed. Go rent a standard flight school 172, add full flaps, pull the power back, and stall it- gentle as a kitten. Take the same 172, no flaps, full power departure stall and you'll get a cute little torque roll (I mean, it's not a Pitts Special or anything) at the top of the stall- all P-factor and torque.

Stall tendencies (the variables you allude to) are functions of wing loading, angle of attack, bank angle (that will drop a wing on you) coordinated/un-coordinated flight, power settings, CG (yes) and yes, flaps.

But in that equation, flaps will generally provide a more gentle, as opposed to less gentle stall. It seems you're singling out flaps- what did they ever do to harm anybody?

Poor little flaps You probably hurt their feelings.

(and I am of course, just kidding around with you)
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