Mar 20, 2013, 01:52 PM in awe of glide... United States, NY, DeRuyter Joined Dec 2012 170 Posts Discussion DlG maximum airspeed I understand that it depends on the structure and drag of the craft, not to mention many other factors. But has anyone ever measured or simply have a good idea of the maximum airspeed of a dlg in a dive? Kirk
 Mar 20, 2013, 01:56 PM hot air rises... Pleasant Grove, UT Joined Jul 2005 8,434 Posts I don't know but I think it's less than launch 'cause if I dive vertically from say 500 ft and pull up just before I splat I don't end up as high as I do from a launch.
 Mar 20, 2013, 02:02 PM Will fly for food Bellevue WA, Joined Dec 2003 7,540 Posts I have measured DLG's at release doing 70+ MPH. I would think in a down line they may get to 60mph but I have not measured it.
 Mar 20, 2013, 02:59 PM Registered User Joined Apr 2009 6,521 Posts I've achieved far higher than launch speeds with the original Zone, ballasted. But, I don't have measurements. One can estimate it from wing drag coefficients and putting in a healthy margin for tails and fuselage. Within reason, max speed is proportional to the square root of the weight. Gerald
 Mar 20, 2013, 03:16 PM Registered User United States, CA, Tehachapi Joined Jun 2011 3,533 Posts Never clocked a DLG in a dive, but I know that the 14oz Blaster 2 I used to fly would really haul. Certainly faster than I was launching it. My 7.5oz Mystic prototype I don't think could quite reach launch speed in a dive. Basically, at terminal velocity in a dive the weight of the plane is equal to the total drag force on the plane. Drag increases with the square of velocity, so if you do a little algebra you can see that terminal velocity is proportional to the square root of the weight, just like G_T said. So if you ballast a plane it'll have a higher terminal velocity.
 Mar 20, 2013, 05:06 PM Transplant Chey WY from Reno Reno Nevada Joined Oct 2007 2,786 Posts Normally, the max speeds I get are a fraction of a second before the plane blows up.
 Mar 20, 2013, 06:05 PM a.k.a. Bob Parks Glendale, AZ Joined Jun 2008 2,719 Posts Mine is always an inch above ground! BP
 Mar 20, 2013, 07:06 PM Who needs a pilot?? Alexandria, VA Joined Jul 2002 1,222 Posts Someone should put in a How-Fast, catch a boomer, then bail at altitude and hold a vertical downline as long as seemingly possible! Video is of course a requirement so we can all witness if there is destruction or not :-) I somewhat think we might throw close to or over terminal velocity anyway. So that means if someone mails me a loaner how-fast, I'd be happy to volunteer. Dan
Mar 20, 2013, 08:03 PM
in awe of glide...
United States, NY, DeRuyter
Joined Dec 2012
170 Posts
Thanks for all your replys. I did a search but was surprised i did not find any threads on maximum airspeed. The airspeed indicator is something to definitely keep an eye on.
Quote:
 Originally Posted by G_T I've achieved far higher than launch speeds with the original Zone, ballasted. But, I don't have measurements. One can estimate it from wing drag coefficients and putting in a healthy margin for tails and fuselage. Within reason, max speed is proportional to the square root of the weight. Gerald
Quote:
 Originally Posted by bwill6 Never clocked a DLG in a dive, but I know that the 14oz Blaster 2 I used to fly would really haul. Certainly faster than I was launching it. My 7.5oz Mystic prototype I don't think could quite reach launch speed in a dive. Basically, at terminal velocity in a dive the weight of the plane is equal to the total drag force on the plane. Drag increases with the square of velocity, so if you do a little algebra you can see that terminal velocity is proportional to the square root of the weight, just like G_T said. So if you ballast a plane it'll have a higher terminal velocity.
It makes sense, the more weight, the more velocity. More velocity in turn more drag...which at some point terminal velocity is acheived. That's my simplified version...
Mar 20, 2013, 08:05 PM
in awe of glide...
United States, NY, DeRuyter
Joined Dec 2012
170 Posts
woo hooo!

Quote:
 Originally Posted by Thermaln2 Normally, the max speeds I get are a fraction of a second before the plane blows up.
Quote:
 Originally Posted by bbbp Mine is always an inch above ground! BP
That sounds like some balistic flying!!
Mar 20, 2013, 08:10 PM
in awe of glide...
United States, NY, DeRuyter
Joined Dec 2012
170 Posts
NIce find!

Quote:
 Originally Posted by danstrider Someone should put in a How-Fast, catch a boomer, then bail at altitude and hold a vertical downline as long as seemingly possible! Video is of course a requirement so we can all witness if there is destruction or not :-) I somewhat think we might throw close to or over terminal velocity anyway. So that means if someone mails me a loaner how-fast, I'd be happy to volunteer. Dan
That is great! Maybe we buy one or two of them, send them around to whoever wants do the vid and record their maximum airspeed.

i can't say i'm up for organizing it, but that would be fun. Good idea Dan.
 Mar 20, 2013, 11:33 PM a.k.a. Bob Parks Glendale, AZ Joined Jun 2008 2,719 Posts It could be calc'd off a BTOA graph. It shows min/max heights and time between two points, but on my setting only to the nearest half second, so not very accurate. If I did it correctly, my partially flapped descent from altitude was about 32 MPH. What does the vario number between two points represent? BP Last edited by bbbp; Mar 21, 2013 at 12:15 AM.
 Mar 21, 2013, 08:21 AM Chuck 'Em and Chase 'Em United States, NY, Plainview Joined Aug 2005 8,120 Posts Why? For what purpose would this be important? Afterall, sailplanes are designed to find lift. As with everything, there are tradeoffs. If you want to work lift, you can do it more easily if you are light but light weight without a power source means that flightspeeds tend to be slower. then again,if there is some fascet that might be interesting, please enlighten us all so we all may partake!!!
Mar 21, 2013, 08:26 AM
Time for me to Fly...
United States, MI, Fenton
Joined Jan 2000
9,149 Posts
Quote:
 Originally Posted by Fly2High Why? For what purpose would this be important? Afterall, sailplanes are designed to find lift. As with everything, there are tradeoffs. If you want to work lift, you can do it more easily if you are light but light weight without a power source means that flightspeeds tend to be slower. then again,if there is some fascet that might be interesting, please enlighten us all so we all may partake!!!
Sometimes it's fun just to satisfy a curiosity. I'd like to know how fast they can fly too.

I wonder how fast you could get one to go with one of your rocket engines on it, Gerald.
 Mar 21, 2013, 10:38 AM Registered User Joined Apr 2009 6,521 Posts Vaporized.