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Jul 15, 2019, 11:02 PM
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Randy Reynolds's Avatar
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Launch height with F3-RES HiStart


I remember reading that someone measured launch heights with varying wind direction. Anyone have a link to that posting? Any information regarding this topic is welcome.

Iím trying to justify 100 Meter Electric launches in order to get more people flying. I do know down the line launches can be over 100 meters.....anyone?
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Jul 16, 2019, 07:53 AM
Sonoran Laser Art
It's been awhile but I think it was Soarhead00.
Jul 16, 2019, 11:32 AM
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Thanks Corky, I'll check with Bob

THe R/C Groups search can be pretty frustratin and I'm not being successful with this one.
Jul 16, 2019, 11:56 AM
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Found it:


Nov 23, 2017, 11:45 AM

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Pgoldsmith
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Firstly, what the Albq guys put on was a fantastic event, don't confuse input with criticism, all remarks by those whose attended were noted and accepted as "input" I'm sure modifications will be made to accommodate where possible at future events.

I talked to everybody there, it was a unamous great time by all, we were all buzzing and excited about the next event.

Launch Testing.
I went out and did some launch testing with the Opal, we had a relatively calm afternoon, however pretty cold, where I could get some experience on launching in different conditions.
I used the spec rubber, and line length, the mono I used was slightly heavier than spec (Some J mono I had) however for practice it's fine.
The reason for the testing was to see how much variation there is with different launch conditions.

My obversation is that if your launching into the wind, everybody will get great launches, Friday and Saturday were both that. It's when it's calm or downwind the launches vary. I had one of those small launch height readers that I use in DLG when practicing for the readout. The actual numbers may not be exact however the variation is.

I did 3 launches into the wind, 3 launches in a. crosswind (90 deg approx) and 3 launches down wind. I stretched the bungee back 30 paces, with the exception with the very last launch, which was 40 paces. The wind did lay down slightly over the hour I did this, so the down wind launches were probably 2 or so mph.
The wind speed was perhaps 5 mph at the start it was consistent, late in the day breeze.
I think you will find these results interesting, and may bring some clarity to the challenges that organizers face.

Into the wind launches:
Launch 1, 334
Launch 2, 365
Launch 3, 321

Crosswind
232,
192,
217.

Downwind
134,
152
125

I did the last Down wind launch by pulling back a additional 10 paces, the model over speed the bungee and shot off lower than the previous launches.

So in summary if your launching into the wind, or even cross wind your launches will be plenty. Down wind is where the problem is.
Now those of you that have been on the competition circuit for a while know that's it's very rare to be in a down wind situation, it basically means it's dead calm with light thermal feeds. So in the rare case this will happen I'm just going to deal with it along with everybody else.
One thing I am going to do based on my testing is continue to work on my launch setup, especially for less than ideal conditions.
When you getting your F3Res model ready make sure you do a lot of launch setup, it really pays off.



So what I'm trying to settle on is when we fly electric in F3-RES and limit the CAM to 100m is that fair when winds are roughly down the HiStart line and it appears that it is. I realize wind speed and direction can have an effect. We'll test these numbers at our field to see if that will hold up. We do fly at about 7000' altitude so that might have it's own effect. I would welcome any commentary from readers.
Jul 17, 2019, 03:20 AM
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Even 100 meters launch can be funny and more challenging/rewarding than 150 meters launch...
With current F3-RES models you can find thermals starting from 120 meters in any weather conditions, so what's the fun ?
European F5J competition cut motor even at 50 meters sometimes
Jul 17, 2019, 10:44 AM
Sagitta Fanboy
Quote:
Originally Posted by renatoa
Even 100 meters launch can be funny and more challenging/rewarding than 150 meters launch...
With current F3-RES models you can find thermals starting from 120 meters in any weather conditions, so what's the fun ?
European F5J competition cut motor even at 50 meters sometimes
F5J competitors are known to cut motors at 20m or below when they think they can get away with it. Low launches win competitions and F5J ships can be handlaunched into lift quite readily (only reason you don't see that in competition is the motor is required to be running when the plane leaves the hand)
Jul 18, 2019, 11:06 AM
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So, renoata and mawz do you have any advice on the topic?
Jul 18, 2019, 11:51 AM
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Sure, to stay with the histart within the limits allowed by the class you compete.
Jul 18, 2019, 11:58 AM
Sagitta Fanboy
Quote:
Originally Posted by Randy Reynolds
So, renoata and mawz do you have any advice on the topic?
The short answer is that I'm not in favour of going mixed launch in F3-RES due to the differing launch windows and timing requirements. Line launches are ~10s and start the timer at line release, electric is ~20-30s and starts the time at the toss, giving the electrics 20 free seconds on the task. Fixing that would be difficult in any situation that doesn't fly electric as a separate group.

As a CD, I generally view Mixed Launch as a solution in search of a problem.

I also don't see it adding to the attraction, but do see it adding to the complexity of the ruleset. There's already a ruleset for 2m-specific electric launch (TALES) and while I'm rather less than fond of it, it exists and folks are flying it. You can also of course always run ALES rules and limit to class B and 100m if desired.
Jul 18, 2019, 02:10 PM
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We start the clock when the motor shuts off at 100 meters so no real timing difference. Even if you start the clock at the toss for electrics you should be deducting time for the launch I would think. The rationale for including mixed launch is for increasing participation and it certainly does that. Of course our club has a lot of woody electric two meters (Heliums). They are certainly not state of the art designs and weigh quite a lot. They tend to be very competitive when the wind blows however.

So getting back on topic, would you have any input in terms of average F3-RES launch heights on legal HiStarts?
Jul 18, 2019, 08:02 PM
Sagitta Fanboy
Quote:
Originally Posted by Randy Reynolds
So getting back on topic, would you have any input in terms of average F3-RES launch heights on legal HiStarts?
Peter's numbers look good, that matches up with what I've seen with my RESolution V2 on a regulation histart.
Jul 18, 2019, 08:08 PM
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Very good, thanks for the feedback. Is the RESolution a Kit?
Jul 18, 2019, 08:15 PM
Sagitta Fanboy
Quote:
Originally Posted by Randy Reynolds
Very good, thanks for the feedback. Is the RESolution a Kit?
Yes. It was a Hoellein/Gruner CNC kit, although I think it's out of production now.

Along with the Miles 2m, the RESolution was one of the transition designs between more traditional 2m RES designs and the modern ultra-light F3-RES designs, so it's heavier (mine is around 570g now, was 600g at build time) and has a much larger wing area (600sq in), but it has a wing loading not too dissimilar to the heavier (450-480g) F3-RES designs. I don't generally give up launch height to the F3-RES designs unless the wind is dead or a tailwind.


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