CEF speed contest Design Discussions

That's nice work Roddie. For spraying in accordance with the family enviromnent régulations, I was thinking of a wooden wine bottle crate with a large hole to which you can connect a flexible hose of a cloth dryer to evacuate smelly gasses.

I haven't done that much yet, but I'm on my way.



Those figures would look nice indeed. And the scale matches!! They cost an arm and a leg though. I never heard of rare earth magnets. I looked it up and they give plenty of possibilities.

Chicken Mark, I HOPE I'm gonna fly that. Building is great fun and I don't think a second about crashing. I spent a lot of time building my JR Satan and saw that disappear into a tree. These things better don't happen but it doesn't discourage me.

Lieven

http://www.ebay.com/itm/171198464464?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

These are the ones I used on my glider.  Seriously strong, and just cost about the same as a fancy coffee.

They are also miniscule. Less than 1mm thick, the stick of 50 was 45mm, and 3mm diameter

Phil

Sorry I've been absent on this thread guys, work is crazy and I have been focusing on other projects to boot. Lots of great work going on with these planes, I'm really happy this thing took off like it has.

Rusty and Roddie ,
What's the feasibility of the ossiliscope timer. I just read that last nite, that would be cool now that prizes are involved.

Jim

Hi guys in anticipation of recieving the bits I need from Texas Timers for my bladder tank. What length should I make the bladder tube? I'm looking forward to trying out a fuel bladder. Any advice on running in my newly built engine would be appreciated.

Cheers Mike  

JPvelo wrote:Sorry I've been absent on this thread guys, work is crazy and I have been focusing on other projects to boot. Lots of great work going on with these planes, I'm really happy this thing took off like it has.

Rusty and Roddie ,
What's the feasibility of the ossiliscope timer. I just read that last nite, that would be cool now that prizes are involved.

Jim

Hey Jim, No need to apologize on this end... This contest has the momentum of a FREIGHT TRAIN! (have you seen the amount of "views" on the thread?   )

Rusty mentioned having a scope... but also mentioned the possibility of something as simple... as an "app". for one. The instrument measures sound/frequency... and should only require a monaural signal, to measure peak frequency timing. A contestant could actually submit a VOX (audio only) file of their flight, to obtain a measurable lap time. Of course there must be visual proof of the flight... but; there being random runs at different locations.. an oscilloscope is the only feasible accurate way to time laps... if not "the" most accurate means.

I will make some inquiries.. as I'm sure Rusty will, to get more info. on obtaining a scope for our official use. I'd be willing to bet that there's computer software available for this, which would greatly simplify the task.

Edit: here's an example.. although I have not tried it.

http://www.zeitnitz.de/Christian/scope_en

I have a friend who is one of the best audio guys in the Northeast. He designs and manufactures the Loudspeakers used currently by Disney.

I asked him for some tips in a letter this afternoon, that I'll share with you.. in case I left anything out. An initial inquiry to him prompted him to ask me, "How fast do these planes go - or alternatively, how fast is a lap?"

Here is my reply:

Dave, these airplanes should average 80-100 mph. I have not done this before, and I don't know what an average lap-time consists of. I would imagine it is more than 1 second.. but less than two... (sorry.. that's quite a deviation) The "fact" is... these type of models are traditionally flown at contests where all the entries are in one place, and the judging is done via a radar detector... (or some other "optical" means to measure the speed in "mph"... and not the lap-time.) Since our contest involves contestants from all over the world, submitting video of their flight for judging... I figured that measuring the audio peaks would be the only way to accurately measure the performance... unless there's a way to do it "optically" from the videos that are submitted.

Internationally, there is a lot of interest.. with a lot of models being built to compete.. including mine. I made the recommendation that the filming be done with the camera being stationary on a tripod, or building a "dock" to hold a phone-cam. There will be a Doppler wave created as the model flies the 84 foot dia. circle (42 foot lines-pilot stands in the center of the circle) I figured that an O-scope may be able to measure the timing between peaks in the SPL. Measuring the sound frequency would not be as accurate, because the engines can and will vary in rpm's while running. This could give false advanced/retarded measurements I would guess. As with all experiments, there must be a "constant" or base-line to measure from. This "constant" would be the Doppler wave. The fastest lap out of 10 will be the official time for that contestant.  

Here's a YouTube vid I found, that comes very close to what we'll be doing. https://www.youtube.com/watch?v=CCURUXSHq6w

As you can "hear"... it may be possible to measure laps by means of audio.. Question is; can the sensitivity of the measuring device be able to separate between the peaks in SPL, enough to give readings in fractions of a second.. and if so; "how many" fractions of a second...  

Roger

So... If there's a way to accurately measure lap-times using sound measurement, my friend should be able to tell us how. I'll report when I hear back from him.

ebeneezer wrote:Hi guys in anticipation of recieving the bits I need from Texas Timers for my bladder tank. What length should I make the bladder tube? I'm looking forward to trying out a fuel bladder. Any advice on running in my newly built engine would be appreciated.

Cheers Mike  

About 1" to 1-1/2" should be good for way more than you'll need for the Reed Speed race. I can put a full ounce in 1-1/2". It stretches like a bratwurst.

Just take the tube and tie a knot in it an inch or so from the end, snip it off, lick your fitting and stuff it in. Seal it with whatever you like; twist tie or o-ring and it's a bladder. No need to secure the connections down the line, it won't blow them off.

Be sure to train it to expand from the front. Hold it in front of the knot so it has to expand from the front and pump it full of air, but not quite all the way. Leave a bit of unfilled tail so as not to over pressure it(applies to fueling too). Clamp it off for a minute or two, then let the air out. After that it will always fill that way.

When filling, keep a spray pump bottle of water where you can reach it blind. It's uncommon to pop one, but better to be ready if you get a face full of fuel. I never have. But I always have my spray bottle primed and close by.

I haven't run a reedy on a bladder... yet, so JP can fill you in on cranking and needling. After you find your needle setting, leave it there, even after you hang the plane up for the day.
Rusty

I'm afraid my scope is too primitive for this. It's so clunky that I would have to guess at where the sweep vernier is pointing and count squares on the screen to get a reading, and only an guesstimate at that. And doppler... it was wishful thinking on my part. Remember to add two feet to the length for the pilots' arms too.

I can still check on apps, but I think the time ticking on the video is one way. The submission needs to come with a note saying which 10 laps are timed.
Rusty

RknRusty wrote:I'm afraid my scope is too primitive for this. It's so clunky that I would have to guess at where the sweep vernier is pointing and count squares on the screen to get a reading, and only an guesstimate at that. And doppler... it was wishful thinking on my part. Remember to add two feet to the length for the pilots' arms too.

I can still check on apps, but I think the time ticking on the video is one way. The submission needs to come with a note saying which 10 laps are timed.
Rusty

Maybe I'm making too much out of this...? But... This could be done a couple of ways "if" the SPL (Sound Pressure Level) "peaks" can be measured within a fraction of a second between "each one" (i.e. each lap).. The fastest "1/2 mile" (10 laps.. starting after the 1st or 2nd completed lap?) and the fastest "lap"... outright. (another prize for this?)

I honestly feel that there "may be" models that will be too close together in lap-times, to be judged using the video times by eye. It would also be nice if everyone knew exactly what their lap-times were... and/or "their individual" exact total 1/2 mi. time.

I realize that this contest is supposed to be "fun"... and one way to assure that; would be in providing the most accurate times possible. Hopefully this can be accomplished through the videos, because it's the only means we have, with us all racing from different locations.

Go low tech, get some surveyor's tape and run it out to the pilot's circle in front of the camera. If there is a "tie" I don't know how to break and have this stay a "fun" level contest.

Phil

Talking about speed and time got me wondering what lap time is at 100 Mph. Using a 44' radius circle 100 MPH is sub 2 second laps or about 19 seconds for 10 laps.
Is that even possible on an 88' dia. circle without falling down?

Don't use a big tank is all I can say.

Here's a handy speed calculator. Don't forget to add your arm length. I usually use 24" for that.
http://www.flycl.co.uk/control_line_speed_calculator.htm
There's a metric to English conversion link on the page.

2 second laps at 44' would be 94mph
3 second laps is 63mph

We all better practice dry flying turning that fast.
Rusty

I plan to fall down, gently, after landing.

Phil

At first I was thinking sub 2sec laps would be no big deal and then I realized that I can't stop and do stunts.   

Cribbs74 wrote:Don't use a big tank is all I can say.

First (only) time I flew the corsair I had two minutes worth of fuel in it. Longest two minutes of my life, put a couple miles on the plane though. Speaking of that,  has anyone calculated distance covered by there flight time contest engine? My sig Skyray has traveled about 150 miles!

Jim

RknRusty wrote:Here's a handy speed calculator. Don't forget to add your arm length. I usually use 24" for that.
http://www.flycl.co.uk/control_line_speed_calculator.htm
There's a metric to English conversion link on the page.

2 second laps at 44' would be 94mph
3 second laps is 63mph

We all better practice dry flying turning that fast.
Rusty

If any of us can come close to a 2 second lap... it will put us "right up there" with some of the best 1/2A proto profile flyers in the country.

Check out Division 6 (West Coast) on this NASS records page... http://www.clspeed.com/node/3  

137mph, I can do that lying down.   

I ordered some 1/32" contest balsa from Tom Morris' Stunthangar Hobby to laminate my Mustang foamboard fuselage and it was broken in half when it arrived. And it wasn't even the right size, it was 3/32". Then Sparky said it was a mistake, they don't even carry 1/32. It's the nicest lightest balsa I've ever seen. It weighed nothing. I'm disappointed. I hope I can find some that thin in Columbia, but it'll be hard balsa. I needed that... for my secret weapon. 
Rusty

Do you have a planer?

RknRusty wrote:I ordered some 1/32" contest balsa from Tom Morris' Stunthangar Hobby to laminate my Mustang foamboard fuselage and it was broken in half when it arrived. And it wasn't even the right size, it was 3/32". Then Sparky said it was a mistake, they don't even carry 1/32. It's the nicest lightest balsa I've ever seen. It weighed nothing. I'm disappointed. I hope I can find some that thin in Columbia, but it'll be hard balsa. I needed that... for my secret weapon. 
Rusty

You know me Rusty... I have suggestions for everything...   You could use that sheet.. (if it's the lightweight contest grade you're looking for) by edge-gluing it back together along the break, with thin CA on a sheet of wax paper.. on a flat surface (holding the pcs. firmly together for 10-15 seconds) Then cut the pc.(s) to the length you need and thumb-tack x2 pcs. of .031 music-wire on either side of the sheet.. and block-sand (with the grain) down to the music-wire, and you'll have 1/32" thick stock. It will sand easily.. so use a fine grit paper. If you can find a nice lightweight pc. of 1/16" sheet.. you could do the same, with a little less sanding. I didn't know that balsa came in 1/32" thick sheet. That's thin!