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RE: NC Speed Event - 1/16/2008 2:08:45 PM   
evan-RCU



Posts: 2541
Joined: 2/4/2002
From: Charlotte, NC, USA
Status: offline 		How about a list of people planning to show... My hands up....

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R/C Anonymous. My name is Evan and I have not flown for 14 hours.

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RE: NC Speed Event - 1/16/2008 3:13:51 PM   
vicman



Posts: 5912
Joined: 12/8/2002
From: Valdese, NC, USA
Status: offline 		OK. I see a bunch of comments from people who are most likely not going to be here. If I am wrong I appologize. If you have a ship sporting a larger engine and are planning to show up feel free to inquire on eligability. We are not interested in sombody running a 50% with a 150 cc down the line. I don't feel the need to clarify every little idea of what can possibly show up. .61 was just a decent and common size that we thought would be a good fit. Again, if you would like to run something fast that pushes that size limit contact me. That's the fun of guys running diffrent things.

We had our club meeting last night where this event was discussed and nobody had any concerns, so it looks like we will be game on. We're not sure of the precise date just yet, I will keep you posted. This is the first time we have tried something like this and are going to include it as part of a fly in event with open flying, glider tow and buddy box time. Depending on how many pilots/planes show up for the game we will modify the event accordingly.
To my knowledge there isn't another event like this in our region, we are looking forward to the reaction.

It's not a race with a gaggle of hardcore rules...just come out and see how fast your stuff is and do it with other guys who like the same things.

Several of us in the club are excited to see what this turns into.

Evan, you and I will hook up very soon.


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RE: NC Speed Event - 1/16/2008 3:37:06 PM   
evan-RCU



Posts: 2541
Joined: 2/4/2002
From: Charlotte, NC, USA
Status: offline 		And Seth, does he still have his Magnum? We have two down here...

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Revver #125, Pico Owners Club #3
R/C Anonymous. My name is Evan and I have not flown for 14 hours.

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RE: NC Speed Event - 1/16/2008 4:36:24 PM   
vicman



Posts: 5912
Joined: 12/8/2002
From: Valdese, NC, USA
Status: offline 		Yep. I will need to get one of mine going for that event also. The cool thing Seth has is a perverted Predator I that is missing 11" off each wingtip he calls the Power Squirrel.


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       Post #: 29

RE: NC Speed Event - 1/16/2008 9:54:51 PM   
I-Love-Jets


 

Posts: 141
Joined: 10/19/2006
From: Düren, GERMANY
Status: offline 		Hi,

the below link shows a guidebook for F3S pilots focussing on the the fully automated electronical speed measurement:

http://www.f3s-speedcup.de/documents/briefing_messung.pdf

The distinct advantages of a modern 1/100 sec accurate electronic measurement device versus the ”old-fashioned“ clocking by hand operated stopwatches are defined.

For non-world record flights (i.e. for the German F3S Mastership) there’s a special speed determination practice in case of pilots achieving only one successful measurement per flight (be it up- or downwind due to pilot error, dying engine etc).

From experience over here, speed results obtained by using top of the range radar guns (preferably STALKER “PRO“) are always higher compared to results acquired through the FAI method (200 m horizontal distance in both directions). These differences have been empirically “discovered” during speed training flights prior to F3S contests. The same speed planes at the same day under equal climatic conditions were tested, flying identical flight pattern (200 m horizontal in both directions), only the type of speed measurement varied.

Results of these two disparate speed measuring techniques can differ up to 10 %, considering the required up- and downwind averaged values. That’s quite much, making evident that radar gun speeds are less significant than time vs. (large) distance measurements while discovering the true potential of a speed plane.

So – to make the 2008 US speeds more international - it would make sense to “convert“ these NC Speed Event radar-gun speeds into FAI-similar speeds by using the factor of 0.9

Best regards


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RE: NC Speed Event - 1/16/2008 11:55:51 PM   
HighPlains


 

Posts: 2545
Joined: 3/2/2003
From: Over da rainbow, KS, USA
Status: offline 		In other words, the airplane is slowing down through the traps after the dive, while the radar picks up the peak speed out of the dive.

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RE: NC Speed Event - 1/17/2008 1:05:51 AM   
Crazy4Flight



Posts: 2187
Joined: 9/15/2002
From: Milford, MI, USA
Status: offline
quote:

ORIGINAL: vicman

OK. I see a bunch of comments from people who are most likely not going to be here. If I am wrong I appologize. .....

It's not a race with a gaggle of hardcore rules...just come out and see how fast your stuff is and do it with other guys who like the same things.



Give me two weeks notice on the date & I will see what I can do.

THREE RULES SPEED:

1) FLY FAST
2) FLY SAFE
3) HAVE FUN

leave the german rule book at home!

BTW is the a 3 mph bonus for inverted speed runs ???

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       Post #: 32

RE: NC Speed Event - 1/17/2008 3:43:49 PM   
vicman



Posts: 5912
Joined: 12/8/2002
From: Valdese, NC, USA
Status: offline 		C4F gets the idea.
quote:

BTW is the a 3 mph bonus for inverted speed runs ???

Can't comment on that but if your fast time Du Jour is inverted, I think one of the guys will be able to scrounge something up for you.


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RE: NC Speed Event - 1/17/2008 3:45:53 PM   
evan-RCU



Posts: 2541
Joined: 2/4/2002
From: Charlotte, NC, USA
Status: offline
quote:

ORIGINAL: vicman

C4F gets the idea.
quote:

BTW is the a 3 mph bonus for inverted speed runs ???

Can't comment on that but if your fast time Du Jour is inverted, I think one of the guys will be able to scrounge something up for you.


If it was me trying this they'd be scrounging bits of balsa off the runway...

< Message edited by evan-RCU -- 1/17/2008 3:46:07 PM >

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R/C Anonymous. My name is Evan and I have not flown for 14 hours.

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RE: NC Speed Event - 1/17/2008 3:56:14 PM   
vicman



Posts: 5912
Joined: 12/8/2002
From: Valdese, NC, USA
Status: offline 		I call dibs on your battery.


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RE: NC Speed Event - 1/23/2008 2:39:50 PM   
I-Love-Jets


 

Posts: 141
Joined: 10/19/2006
From: Düren, GERMANY
Status: offline
quote:

ORIGINAL: iron eagel
There is a problem with the photo triggered time trials in as much as the rise time of the detectors used are often not included in the calculations. What I mean is for many photo sensitive devices there is a lag time between the event and the time that the device actually changes state.


Hey guys,

there’s no problem due to lag of time!

We should compare accuracy of:

1. the well known human hand operated stop-watch method (being accurate enough for many FAI records in the past) versus
2. the new photo cell triggered fully electronical device

The latter is several times more accurate (read: very little lag!) than the first. So it is no surprise that nowadays the FAI consequently tries to exclude the “human factor“ when it comes to objective speed measurements.

Moreover that unavoidable very small (you can say negligible) lag of time between the event (plane “cuts“ light barrier) and the time that the device actually changes state does NOT have an effect on the final speed. Why – because we do have TWO identical photo cells at a distance of 200 m, each of them producing identical (negligible) lag!

The photo triggered device over here has been meticulously FAI approved. In fact at 1/100 sec accuracy it is much more precise than the pedantic FAI actually demands.







Highplains already pointed out why radar-gun derived speeds are always higher than speeds through a FAI 200 m speed trap.

quote:

ORIGINAL: HighPlains
In other words, the airplane is slowing down through the traps after the dive, while the radar picks up the peak speed out of the dive.


So let's face it:

The longer the distance of a speed trap the more difficult it s to maintain the speed but the more meaningful the obtained speed will be. This is were a less good speed plane design versus a very good design show their true aerodynamical potential. So this is the challenge – to outflank drag over a certain distance in time! To know the speed at a certain point of time is only little significant for objective comparisons!

That is also the reason why all dynamic soaring speed readings cannot and will never be accepted as official FAI records.

It is also clear that radar gun speed results are almost identical to audio-Doppler speed results, as both are based on the same physical principles. So what does apply to radar gun speeds also applies to video/audio-Doppler shift derived speeds – both aren’t really significant internationally.

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RE: NC Speed Event - 1/23/2008 2:41:33 PM   
I-Love-Jets


 

Posts: 141
Joined: 10/19/2006
From: Düren, GERMANY
Status: offline

An example: The photo cell automatically triggered speed readings during F2A control line speed events are very accurate – and they have to be because these events are mostly FAI governed international speed trials. In fact they need to get readings over a certain distance because their speed improvements from year to year often range within only one mph! F2A speed freaks would never trust radar gun or audio based Doppler readings!

Another example: The 2007 German speed event was finished with a highest top speed of 246 mph.





This particular 10 cc driven fully custom made speed machine would have set a new FAI world record if it had a wing load of less than 75 grams/dm^2 (unfortunately is was much higher BTW). However these objective (i.e. internationally comparable) 246 mph speed as a FAI based result (200 m averaged) translates to about “ridiculous“ 270 mph peak speed if a radar gun or the audio Doppler shift method had been used during the runs.

Personally I am quite sure FAI approved true 270 mph will never ever be reached with IC powered R/C planes up to 10 cc in future!




So to detect the real capabilities of a speed plane means to learn sustaining speed very well over a certain horizontal distance. Many speed plane designs (including prop choice) do exist that actually do not maintain top speed well in this discipline. So R/C speed flight is much more difficult than most of us would imagine...

Regards

P.S. To achieve more succes in the fields of R&D several people over here (also aeronautical engineers) started calculating new FAI specific straight-in-line wing airfoils plus new speed prop designs over the last year. Especially sophisticated prop design should provide promising results in future. In any case molds for these wings and props will be CNC machined to transfer the calculated aerodynamic benefits into real life (some molds already exist). In addition there is a new simulation software tool (developed by a well known aeronautical engineer) that calculates terminal speed of a R/C speed plane within a simulated FAI speed trap. Speed plane weight, prop size, unloaded rpm, engine output, starting velocity at user-defined altitude, diving angle, radius of pulling out and other factors can be adjusted to simulate the most efficient 200 m speed trap runs.





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RE: NC Speed Event - 1/23/2008 5:42:56 PM   
vicman



Posts: 5912
Joined: 12/8/2002
From: Valdese, NC, USA
Status: offline 		We are planning to use widely accepted RHF rules for our event.

That trophy must be pretty heavy

I'm only poking fun ILJ , you guys are at the cutting edge of high speed models and we all are impressed by what is done over there.


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RE: NC Speed Event - 5/14/2008 6:33:59 PM