Dual-Deploy Contest in North Georgia

[Blankjorge]

Do you Dual-Deploy?

Southern Area Rocketry (NAR Section 571) would like to invite everyone to a contest we are sponsoring in March. Please come on over and show us that you know DD better then we do….you probably do. Please see www.soarrocketry.org for details and updates.

SoAR's Dual Deploy for Model Rockets Contest
Date: March 27, 2010 All launches must occur during the scheduled launch window.

Location: TurfSouth Sod Farm, Hoschton, GA

Contestants are required to build and fly a model rocket (G motor or less, 3.3 pounds liftoff mass or less) that will use dual-deploy (altimeter based) recovery. The winner is the entrant whose rocket goes the highest and lands closest to the original launch pad.

Rocket must be within Model Rocket parameters:
-Total Impulse must be “G” or less
- Weighs no more than 1,500 grams (53 ounces), including the propellant
- Rocket must use Electronic Dual-Deployment for recovery. The intent is to encourage entrants to use altimeter based deployment for apogee/drogue and main parachute deployment. Motor based ejection for apogee/drogue deployment backup is permitted, but the altimeter apogee event should still be used.

No parachute/streamer is required at apogee; however, ballistic return from apogee is considered unsafe and will constitute a DQ. Some process for reducing velocity from Apogee to Main must be employed

Only commercially available altimeters will be allowed. Modifications to a commercially available altimeter’s program or design are not allowed

Final descent under the main parachute must not be more than 22 fps. All recovery devices must function as designed (yes, a tangled chute constitutes a DQ, but motor based ejection at apogee is O.K). Descent rates will be computed based on gross weight and main parachute size and design

Damage beyond ¼” zipper or paint scratches constitute a DQ

Score is determined as the maximum altitude reached (in feet) divided by the rocket’s landing distance from the original launch pad (in yards). The judges will provide a laser range finder for the landing distance determination. The rocket must be returned to judges table for the altimeter reading

The entire rocket must be recovered.

High score wins the collected entry fees. You must be present to win.

An instructional video series on dual deploy that should be usable in model rockets is available from Apogee Components.

Entry Fee: $5.00 per rocket entry (multiple flights allowed).

 

[Pantherjon]

That sounds like a lot of fun, Jorge! And I would have the perfect rocket/motor combo to compete, and would, if only: it wasn't 200+ miles to the field from here and I didn't work that weekend. That one 'Must be present to win' rule gets me all the time..Dang! Curious how high is the waiver at the Hochston field?

 

[flight4]

Hey there Jorge. You've already seen the rocket I am building for the contest. I'm still trying to figure out what chute to put in it. Perhaps for me and everyone you can post details of how the descent rate will be calculated. I already know I will have to up my chute to meet 22fps.

My guess for gross weight would be the rocket weight plus empty motor casing. So does that mean the rocket will be weighed after recovery?

And also, what particular algorithm or calculator will be used to determine the descent rate?

 

[Blankjorge]

Hi Pantherjon!

I truly understand the driving issue. Right now, if you live in Atlanta, the nearest high power field is either Manchester, Tn (150 mi.) or Lilly, Ga. (150 mi.). We have a field east of Atlanta (Charlie Elliot Wildlife Center) but we can only use outside of the hunting season (the rangers don't want any of us getting mistaken for game....hey, what's the limit on rocket scientists?)

anyway...

The field at Hoschton (and thus this contest) is waiver-less. Although the field dimensions (~2000 x ~1500) are ample, we have homes that border the property and thus prevent any high power rocketry. We could waiver the maximum weight, but I'm not sure I want anyone launching more than 3.3 lbs on a G80.

SoAR uses fields in Lilly, Ga. and the Charlie Elliot Wildlife Center for high power flight. With any luck, SoAR will announce the acquisition of a field midway between Atlanta, Ga. and Chattanooga, Tn. a little later this winter with a planned waivered altitude of 8,000 ft...wish us luck!

 

[Blankjorge]

People, please don't flame me. The chute calculator selected is free and can be downloaded and run on a laptop at the field.

I completely accept that there are probably better chute calculators out there; however, in the name of expidiency and cheapness, I've chosen to use IARG calculator. I'm open to other calculators, but they must be downloadable and be able to calculate the rate for common parachute structures. Send me a PM and I'm sure we can reach a happy compromise.

That having been said, go to:

www.thefintels.com/aer/software.htm

and drop down to the descent rate calculator. Make sure that if you're ignoring the drogue chute that you enter zeroes in the drogue chute fields (otherwise you get a conversion error and the application crashes).

 

[flight4]

So I guess we'll have to weigh the rocket post-flight, with all rocket parts and including the spent motor (su or reloadable). That should work.

 

[Blankjorge]

David,
I think the easiest approach is to weigh the rockets before launch and subtract the propellant weight from the rocket's weight, then use the calculated "empty" weight to drive the descent rate computation. We don't want to DQ someone after an otherwise successful flight....plus, but not performing the check before, we might be condoning an unsafe situation.

I'm open on this. Does anyone else have an observation/suggestion?

 

[RoyAtl]

That sounds like a lot of fun, Jorge! And I would have the perfect rocket/motor combo to compete, and would, if only: it wasn't 200+ miles to the field from here and I didn't work that weekend. That one 'Must be present to win' rule gets me all the time..Dang! Curious how high is the waiver at the Hochston field?

No waiver, this is a model rocket (i.e. FAA Class 1) field. A subdivision borders the field to the west.

 

[flight4]

David,
I think the easiest approach is to weigh the rockets before launch and subtract the propellant weight from the rocket's weight, then use the calculated "empty" weight to drive the descent rate computation. We don't want to DQ someone after an otherwise successful flight....plus, but not performing the check before, we might be condoning an unsafe situation.

I'm open on this. Does anyone else have an observation/suggestion?

Right. I think I know how to do my end of it. Mainly I'm curious how the evaluation will be done on the field. If we will be weighing the recovered rocket then subtracting the propellant weight to calc what the right chute will work great.

of course to make this all the more complicated do you factor the weight of the parachute when calculating descent rate for a given chute?

My head is starting to hurt. See what you started

 

[sandmantoy]

Right. I think I know how to do my end of it. Mainly I'm curious how the evaluation will be done on the field. If we will be weighing the recovered rocket then subtracting the propellant weight to calc what the right chute will work great.

of course to make this all the more complicated do you factor the weight of the parachute when calculating descent rate for a given chute?

My head is starting to hurt. See what you started

I think you would take the weight of the rocket ready for flight, including motor. For calculating the decent rate I would not include the chute weight since it will be out of the rocket and it's weight will not be included in the decent. It's weight will be included in the accent as it is lifted with the rest of the mass. If you want to get picky use the weight of a spent motor for calculating a decent rate also.

I love dual deploy and little rockets to for the challenge, to bad I am to far away Sounds like an excellent contest