2 Questions
- Thread starter Sluggo
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NAR Safety Code:
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9. Launch Site. I will launch my rocket outdoors, in an open area at least as large as shown in the accompanying table, and in safe weather conditions with wind speeds no greater than 20 miles per hour.
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Anything above the pad safely is good to me! Most of my MPR hit 1200-1700ft (I can still see it). Planning to go higher when I finish up my Eggtimer Mini's.
About the wind...there's much more than just pure wind speed. Overstable rockets weathercock, drift and wind direction need to be taken into account and the size of your field. Windy days typically mean longer walks. Apps like Windy help with looking at winds at different altitudes as well. Calm on the surface and 10mph at 1000 ft will make for a long walk as well.
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9. Launch Site. I will launch my rocket outdoors, in an open area at least as large as shown in the accompanying table, and in safe weather conditions with wind speeds no greater than 20 miles per hour.
...
Anything above the pad safely is good to me! Most of my MPR hit 1200-1700ft (I can still see it). Planning to go higher when I finish up my Eggtimer Mini's.
About the wind...there's much more than just pure wind speed. Overstable rockets weathercock, drift and wind direction need to be taken into account and the size of your field. Windy days typically mean longer walks. Apps like Windy help with looking at winds at different altitudes as well. Calm on the surface and 10mph at 1000 ft will make for a long walk as well.
Nice reply. Perfect example of the things I want to hear. I wish more members would reply here. Thanks for posting that up for me.
heada
Well-Known Member
You can mitigate some of the weathercocking by using different rocket designs. Smaller fin areas are impacted by winds less. Tube-fin rockets are impacted the least. You can also angle the rod so that the impact of weathercocking is negated and using a rail is more common. A 54mm diameter LOC Zeus, with it's huge fins, is going to be massively impacted by wind when compared to a 54mm diameter LOC NukeProMaxx.
All of that is on the way up. For the way down, streamers and spill-holes in parachutes help reduce drift. So does dual-deployment (an option for mid-power, not as much for low-power)
I don't fly in anything higher than ~15mph because I'm lazy and don't want to walk far but for rockets not going very high and less impacted by wind, I'll go right up to 20 mph.
For MPR, I like to watch the entire flight so anything below ~2500 ft, depending on the rocket. Normally lower than that but a good 2 stage or a cluster is hard to keep low.
All of that is on the way up. For the way down, streamers and spill-holes in parachutes help reduce drift. So does dual-deployment (an option for mid-power, not as much for low-power)
I don't fly in anything higher than ~15mph because I'm lazy and don't want to walk far but for rockets not going very high and less impacted by wind, I'll go right up to 20 mph.
For MPR, I like to watch the entire flight so anything below ~2500 ft, depending on the rocket. Normally lower than that but a good 2 stage or a cluster is hard to keep low.
Scott_650
Well-Known Member
Another one of those “depends“ questions - shawn_rockets answer does a great job of covering some good general rules. When I launch with my club, since we have a much bigger recovery area on the club field than the local dairy farm I use for personal launches, my wind velocity tolerance goes up from still conditions to 15-18-ish mph winds. Using a Jolly Logic Chute Release also means I’ll launch in brisker winds than without one. One thing I’m looking forward to when I build my first dual deploy rocket is the ability to launch in higher winds since there’s much more control over the recovery process. And as far as apogee goes I’m a low and slow guy in that I like watching the entire flight so staying under 1500’ matters for me. Some folks love to let it rip all the way to the waiver height which, in brisker winds, can mean a long walk or a lost rocket.
Scott_650
Well-Known Member
If my eyes were better I’d be right in line with 2500’ but too many years on the equipment is definitely a limiting factor
Charles_McG
Ciderwright
12-15mph, given a 12-15G liftoff.
0' AGL. I like recoveries.
0' AGL. I like recoveries.
For LPR/MPR, I prefer to launch in less than 10 mph winds, but that doesn't always happen. If I have a well known rocket, I will push that a bit, and if I can fit a Jolly Logic chute release into it, that rule goes out the window. Of course, when I add the JLCR, I have to add a tracker beacon, and you end up with a cheap rocket with close to $200 worth of avionics in it. At least you have a good chance of recovery.
If I'm just flying a rocket that deploys the main at apogee, I try to keep my altitude less than 2000 ft.
Both of the clubs we fly with have big waivers and lots of open area to recover in, so my inner "Wildman" takes over for high power. Right now my favorite altitude is 28,905 ft. But that could change if I can get the right propellant mix and grain geometry in my new 75/9000 casing....
Long recoveries don't bother me, I like to hike and use tracking devices to find my rockets. A good day of flying rockets usually includes over 10 miles of hiking.
If I'm just flying a rocket that deploys the main at apogee, I try to keep my altitude less than 2000 ft.
Both of the clubs we fly with have big waivers and lots of open area to recover in, so my inner "Wildman" takes over for high power. Right now my favorite altitude is 28,905 ft. But that could change if I can get the right propellant mix and grain geometry in my new 75/9000 casing....
Long recoveries don't bother me, I like to hike and use tracking devices to find my rockets. A good day of flying rockets usually includes over 10 miles of hiking.
Wow. That is pretty neat. Thanks for all the great posts here.!!
I've been flying in a local park/schoolyard. In those conditions, I only fly in calm wind (probably less than 5mph but I've got no way to measure it) and I fly rocket/engine combinations that OpenRocket simulates as having a maximum altitude of 100 meters or less.
If I were flying in a better field, I'd be flying much higher.
If I were flying in a better field, I'd be flying much higher.
I’m always on the lookout for calm winds. Otherwise I launch the A/B rockets. I find the local news website has the most accurate predictions. I think they average the different wind models found on Windy or such. Problem is I have meetings on Friday and Monday mornings.
I don't like losing sight of my rockets at this point in life since I have to depend on others to retrieve my rockets. 10 mph winds are the limit for this same reason. Being in a power chair sucks.
Flying ceases to be much fun for me when the winds gust past ~15 mph. If I have to use the chin tie for my Tilley hat to keep it on, it's gotten too windy. That said, if I am traveling any distance to go fly, I bring along an Alpha III with a streamer in it that I feel OK flying right up to the Safety Code limit and/or under damp/rainy conditions, just so I can say I got to fly in spite of the conditions.
Altitudes depend entirely on what field and how windy on a given day. Anywhere from couple of hundred feet to a couple of thousand most of the time. When we can actually go to big launches again I have a desire to do a mile-high flight at my favorite sod farm on the other side of the state. If you just plotted the altitudes of my 359 flights in 2020 (almost all of which were made at one large park - #123 ) you'll probably see that ~700 feet was the most common (Nova Payloader on a C6-5).
Altitudes depend entirely on what field and how windy on a given day. Anywhere from couple of hundred feet to a couple of thousand most of the time. When we can actually go to big launches again I have a desire to do a mile-high flight at my favorite sod farm on the other side of the state. If you just plotted the altitudes of my 359 flights in 2020 (almost all of which were made at one large park - #123 ) you'll probably see that ~700 feet was the most common (Nova Payloader on a C6-5).
Max wind I'd hold on is anything 15mph and higher.
Like Wayco we have a pretty high waiver. Anything flying over 20k is awesome. I like minimum diameter long burn set up to push max altitudes. Have trackers and lots of open Prarie. Don't mind a hike to go get it either. once I can get my own long burn motors further dialed in want to push towards 50k. And eventually more of course.
Like Wayco we have a pretty high waiver. Anything flying over 20k is awesome. I like minimum diameter long burn set up to push max altitudes. Have trackers and lots of open Prarie. Don't mind a hike to go get it either. once I can get my own long burn motors further dialed in want to push towards 50k. And eventually more of course.
How much wind. While there is a NAR safety code, I don't follow it. It's not that it is inaccurate, I'm simply lazy and don't want to chase my rockets forever. In my opinion, their rule of 20 mph is way too high. When choosing rockets to launch on any given day, I look at wind speed, cloud cover and the location I'm flying. I don't fly anything in winds over 10 mph at ground level. When winds are reaching that upper 6-10mph range for me I tend to shy away from rockets with large fin area. Rockets like the Estes Phoenix, Lynx, Interceptor or Hawk would stay grounded as they tend to be more effected by wind. I'll fly more traditional 3 and 4 fin designs.
Favorite altitude changes based on my location. If I'm flying locally in parks I tend to go low. 400-500ft is plenty as there are trees, roads and buildings everywhere and I like to get my stuff back. If I'm up at Bong Rec in WI. I am normally fine with going up 1250-1500ft. Yeah it can start to be a bit of a walk but I have only lost a couple and they were all to water landings.
The last couple of years we have been out in AZ for the holidays and found a spot where literally sky's the limit. Mind you, we are some 25 miles from any town or business and you are normally all alone out there until nightfall when the "interesting" people come out. We found ourselves doing silly stuff to see how high it will go. Out there you can fly 5000ft without worry. We were routinely flying 2000-3000ft with no issues. This is the only place I have ever flown an Apogee Aspire on a 29mm motor and got it back
Bruce
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I have heard that tube-fin rockets also tend to roll less than conventional flat fin rockets.
What is it about tube-fin rockets that lessens the weathercocking and rolling?
Nytrunner
Pop lugs, not drugs
Tubes don't present flat weather-vane surfaces to the wind.
Plus, they have more of a symmetric side profile (bundle of round surfaces instead of one fin at this angle and another fin at that angle, and the other 1,2 fin(s) shadowed behind them)
I had a feeling I was overly conservative on my flying conditions but I am okay with that.
Winds: 5mph or less with gusts under 10mph
Alt: 600ft in my front yard and 1800 when I'm out in a horse pasture.
Winds: 5mph or less with gusts under 10mph
Alt: 600ft in my front yard and 1800 when I'm out in a horse pasture.
Bruce
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It would seem that tube-fins not presenting flat weather-vane surfaces to the wind would lower their effectiveness at stabilizing the rocket too. So you'd need bigger fins to compensate and bigger fins might weather-vane more than smaller fins..
I guess I can't follow the side profile explanation. How would round surfaces weather-vane less? And don't tube-fin rockets have fins shadowed behind them too?
I'm not doubting the explanation, just having a hard time understanding. Are there online links that possibly explain more?
Thanks!
Is it that the tubes themselves are providing the stability with the flow going through them? Regardless of the wind direction the airflow coming OUT of the tube would be parallel to the tube direction? Essentially air vectoring... maybe... but just a guess with no on hand math to support it.
Bruce.. Think about it...what will catch more of the wind...a flat, wide surface vs a smaller, round surface. Plus add that fins are completely enveloping the airframe and, yes , makes sense more stable or less weathercocking. What I wonder is because they are smaller, there must be a limit to the size of airframe, width or length, they are more effective than fins.
heada
Well-Known Member
Vertical stabilization is based on frontal surface area, total surface area and velocity. Frontal surface area is the leading edge of the fin. In the case of a tube-fin, its the circumference of the tube. In a traditional flat fin, its the leading edge. Total surface area is the area of the cylinder (both inside and out) for the tube-fin and the normal area (both sides) for the flat fin. Last is velocity but for our purposes we'll assume they're the same.
So for a 6 tube-fin rocket (6 tubes around a central tube fits just about perfectly), each one being 54mm in diameter and 98mm long.... we get ((2*pi*r)*6)=2036mm frontal area and a surface area ((2036*98)*2) of 399056mm^2
For a 6 flat-fin rocket, each one being 4in wide by 6 inch long square (for ease of math).... we get (98*6)=588mm frontal area and a surface area (588*150*2) of 176400 mm^2
Both frontal area and total surface area are not factored in equally. Frontal area has more of an impact than total surface area and more total surface area causes higher drag (increasing with velocity, that's why you don't see supersonic tube-fin rockets) so it isn't as cut-and-dry as I'm implying but for general comparison, it works out this way. That vast difference is why tube-fins give better vertical stabilization.
Cross winds impact 50% of the surface of a flat fin (side facing the wind) whereas a tube-fin impacts only 1/4 of the tube (none of the inside and only half of the outside) plus since its a curved surface, as you move out from the center of the tube, the angle the wind is impacting the surface becomes less and less perpendicular and so less impactful.
Testing vertical flight stability of flat fins vs tube-fins isn't too hard. Build 2 rockets the same except for the fins and fly them both a few times and see which one flies straighter. Testing cross-wind impact is super easy. Get a tube, a sheet of balsa and a desk fan. Set the fan in front of the tube and the sheet of balsa and see which is moved by the fan.
*edit:fixed my math failures
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Great Bruce so you have thought about it. And all I provided was a quick geometric analysis while you "did the math". Thanks.
Las Vegas is the least windy place I've ever lived. On occasion it blows hard—45-60 mph. But that's rare. Right now, the wind at Jean Dry Lake Bed (20 minutes south of where I live) is 6 mph, according to Windfinder. Forecast for tomorrow is 3 mph from 7am to 4pm. Friday, 2 mph at 7am, 3 mph at 10am, 1 mph at 1pm.
That's pretty typical here.
When the wind is 10 mph or higher at JDLB, you'll walk farther to recover your rocket. But on a lake bed that measures ~1 mile by 2 miles, with surrounding area (very short, dry brush) 4 miles by 8 miles, you're hard-pressed to lose a rocket that flies 4,000' AGL or less.
(The only problem at JDLB is summer temps, which will hit 110-120 degrees in July and August.)
As far as favorite altitude, I've got an Estes Patriot, modified for an E engine, that will hit 1400 feet. And a scratch built 2.6" three-engine cluster rocket that will reach 2000. So I'd call those my favorites. (Until I build something that will hit 3000, and then that will be my favorite.)
That's pretty typical here.
When the wind is 10 mph or higher at JDLB, you'll walk farther to recover your rocket. But on a lake bed that measures ~1 mile by 2 miles, with surrounding area (very short, dry brush) 4 miles by 8 miles, you're hard-pressed to lose a rocket that flies 4,000' AGL or less.
(The only problem at JDLB is summer temps, which will hit 110-120 degrees in July and August.)
As far as favorite altitude, I've got an Estes Patriot, modified for an E engine, that will hit 1400 feet. And a scratch built 2.6" three-engine cluster rocket that will reach 2000. So I'd call those my favorites. (Until I build something that will hit 3000, and then that will be my favorite.)
heada
Well-Known Member
There was a guy at our LPR launch site that was in a power chair. He'd prep and launch the rocket and "pay" a kid to retrieve it by giving them a kit or pack of motors. He got to launch much more often and higher and the kids got kits and motors. win-win kinda thing.
@Sluggo I really don't try for altitude anymore. I like watching the whole launch from beginning to touchdown. And I'm 70 and need a hip replacement so I really can't walk a good distance right now. As soon as COVID calms down I will get my left hip replaced. So I launch when winds are 10mph or less for LPR. I also fly HPR and use dual deployment with a small drogue chute and set the altimeter to pop the main at 400'.
OP here.... Thanks for all the great replies.
I have built 6 rockets over the past couple months. They range in weight from 7oz. up to 20oz. I went to the local hobby shop and I've bought 13 Aerotech motors ranging from E30 to a G80. I'm going to take my time burning through the 13 motors. I figure I'll fly 3 rockets on any given day. The maiden flights will mostly be between 1000 and 1500ft. The FlameThrower is a 2 motor cluster so it will go about 1900ft. on its first flight. The Ventris made by Estes I believe will hit 1500+ feet on a G74 according to the motor packaging. My next build will be a LOC Graduator. I have a great field to fly in solo. Once the cows are gone in a couple weeks I will walk the field and sort of get my bearings. And check the short grass for dryness and talk to the landowner about fire danger. If we both decide its safe I will fly. I'll post a link to all 6 models here. The Ventris came from the local shop and the other 5 all came from Apogee. I have no link to the Ventris.
I'm curious to see how many of you will lecture me. lol.!! These will be my first ever flights of MPRockets. Lets see where this goes.... hee. Pictures too.!!
Rising Star (apogeerockets.com)
Sky-Torpedo (apogeerockets.com)
Dynastar Flamethrower (apogeerockets.com)
T-LOC (apogeerockets.com)
LOC 2.63" Patriot Model Rocket Kit (apogeerockets.com)
I have built 6 rockets over the past couple months. They range in weight from 7oz. up to 20oz. I went to the local hobby shop and I've bought 13 Aerotech motors ranging from E30 to a G80. I'm going to take my time burning through the 13 motors. I figure I'll fly 3 rockets on any given day. The maiden flights will mostly be between 1000 and 1500ft. The FlameThrower is a 2 motor cluster so it will go about 1900ft. on its first flight. The Ventris made by Estes I believe will hit 1500+ feet on a G74 according to the motor packaging. My next build will be a LOC Graduator. I have a great field to fly in solo. Once the cows are gone in a couple weeks I will walk the field and sort of get my bearings. And check the short grass for dryness and talk to the landowner about fire danger. If we both decide its safe I will fly. I'll post a link to all 6 models here. The Ventris came from the local shop and the other 5 all came from Apogee. I have no link to the Ventris.
I'm curious to see how many of you will lecture me. lol.!! These will be my first ever flights of MPRockets. Lets see where this goes.... hee. Pictures too.!!
Rising Star (apogeerockets.com)
Sky-Torpedo (apogeerockets.com)
Dynastar Flamethrower (apogeerockets.com)
T-LOC (apogeerockets.com)
LOC 2.63" Patriot Model Rocket Kit (apogeerockets.com)
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I select rockets and engines that are appropriate for the winds. I tend to use lower power in stronger winds. Usually a "B" instead of a "C". Consider using a parachute spill hole when the winds are up. \ I like 1000', a nice round figure.
