Last year about this time, I flew on an off weekend for QUARK with Chan Stevens up at VOA. We were both flying birds for EMRR reviews, and we both had problems, although Chan's problem didn't threaten to incinerate acreage. Chan's problem bird was the Sunward Gravity Rider. He built it per the instructions, using a single 18mm engine, which was in no way close to being up to the task of lifting this big bird skyward. Even though the performance wasn't there, I was impressed with the looks of this rocket, (which, if you aren't familiar with it, is based on an old Canaroc design whose name currently escapes me.) I ordered one of my own a couple of weeks back from Red Arrow Hobbies and started construction on it this weekend. I also ordered the Galactic Wave, which I fitted with a 24mm engine mount. This left me with two Sunward 18mm engine mounts, both of which I planned to put in the Gravity Rider to give it a little extra off the pad. Things have worked out well thus far, but I'm having a little trouble coming up with a recovery method. The main body of the Gravity Rider is two lengths of BT-56 glued side by side. Each of these tubes has its own nose cone, which opens up the possibility of dual parachutes, which is where I'm having trouble. Would dual parachutes be asking for trouble in such close quarters? Should I just put a small vent hole in one tube to vent the exhaust gases and stick with a single chute? Should I just have the tube without a chute blow its cone and somehow attach it to the other cone? I'm hoping to fly this if I'm feeling decent enough to attend our club launch this weekend, so any help you guys may be able to provide would be most appreciated. I should have pics of both birds soon. Both projects are coming along nicely.

__________________
Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Centuri Mini Dactyl Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc Starfighter Scorpion Estes F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II, Xarconian Cruiser Semroc Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark, Groonie Der V 1/2

If you intend to have only one ejection charge, one plugged, I'd single tube and chute it. Make both functional, with tether, and you can switch off deployment from either.

Another Idea might be cool. If you vent the tubes together and seal the ejection charge side's cone, the charge side can baffle to the deployment side. Odd enough to impress me if it works.

Bob

Bill,

If I remember right, the Gravity Rider is a "not too impressive" clone of the Canaroc Antares. The Antares I built did well under a single parachute which surprised me because I thought it may tangle in the longer BT-20 tube once deployed. On three flights, I had no problems (of course, I think I made my shock cord long enough to extend beyond it....I'll have to check when I get home). As for dual deployment, I think I'd be hesitant to try it for two reasons...one being the better possibility of tangling in the longer BT-20 tube, and two the possibility of tangling with each other for the same reason you noted, so close together. Ever consider clustering with the motor tubes vented to the BT-20 for single parachute deployment? An 18" parachute might be tight.....

__________________
Don
NAR 53455
"Carpe Diem"

While pondering the same kit the other day, I thought that if I built it, I'd go for the dual parachutes, despite the tangle risk. Simple, yet cool if it works!

__________________
Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

Bill,

I've been pondering the same dilemma for my upscale Canaroc Antares.

http://forums.rocketshoppe.com/showthread.php?t=1315

I've got dual 24mm mounts, and was thinking about going with a chute in each main body tube. One idea was to make the shock cords different lengths, but I wonder if that would just tangle the chute/cone attached to the shorter shock cord around the length of longer shock cord next to it.

Later,
EV

You know...the tangle issue may be a mute point. A parachute full of air should hold the lines apart (somewhat). Kinda similar to the three parachutes used for the Apollo capsule (real one). They all deployed relatively close together but the full chutes seemed to just hold them apart. Also, doesn't the scale Saturn V have two parachutes on a single shock cord? I can't remember (still at work).

__________________
Don
NAR 53455
"Carpe Diem"

I think the Gravity Rider might be an upscale. All of the tubes are BT-56, so fitting in chutes won't be a problem.

__________________
Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Centuri Mini Dactyl Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc Starfighter Scorpion Estes F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II, Xarconian Cruiser Semroc Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark, Groonie Der V 1/2

I've had my kit about a year, and all I;ve done so far is cut the angled tubes.

modification plans include replacing the sunward cones with PNC56 cones, and was thinking on putting an 18mm mount on one side, and a 24mm mount on the other, so I can fly on either.

as for the dual chutes, should be ok, just use different lengths of shock cord for each, and the canopies will stay seperated. that trick has worked for me .

~ AL

Cutting the tubes was a bitch. Those templates they provide are almost useless. They need to be re-done with more precision than freehand can provide. The two ends don't even match up.

I like the idea of exchanging the cockpit cones for plain BT-56 cones.

__________________
Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Centuri Mini Dactyl Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc Starfighter Scorpion Estes F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II, Xarconian Cruiser Semroc Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark, Groonie Der V 1/2

I finished the construction this weekend while I was watching the playoffs. Both days of the QUARK launch were rained out, so I've yet to fly them. The good news is that they'll be finished by the next launch in two weeks. Nice looking kits, but the stickers have to go and the instructions could use some of Semroc's touch.

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__________________
Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Centuri Mini Dactyl Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc Starfighter Scorpion Estes F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II, Xarconian Cruiser Semroc Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark, Groonie Der V 1/2