Parachute Recommendation for 1/4 PML Patriot

[Estimado]

Hello,
I am building a 1/4 PML Patriot. I plan on flying it at high desert areas of Oregon which is a rather hard surface. The kit came with a 48" nylon chute with a center spill hole. This will allow for a faster decent that may cause a problem on harder landing surfaces.

I would appreciate any recomendations of any appropriate chute size and brand to use as a replacement. I plan on flying it single deploy without the piston ejection.

Rich

 

[kandsrockets]

What is the weight of the rocket?

 

[Estimado]

Scott,
It weighs approximately 4 lbs without a motor, nomex blanket or altimeter.
Rich

 

[kandsrockets]

Scott,
It weighs approximately 4 lbs without a motor, nomex blanket or altimeter.
Rich

Take a look at one of our KSR-7 chutes. It is for 4.5 to 8.2 lbs at 15 to 20 fps. http://www.kandsrockets.com/ksr.htm Depending on your space you may want to go with the 550 cords over the TN cords.

 

[dave carver]

I was going to say 48" before you said that's what you have. I know of 54" ones and a 6' X form would be bigger but drift becomes a factor with the X form most likely would be my choice.

 

[cjl]

Scott,
It weighs approximately 4 lbs without a motor, nomex blanket or altimeter.
Rich

48" should be about the right size. Much bigger and you start getting a LOT of drift. If you're really concerned, a 48" spherachute (from GLR) would bring it down a bit slower, or a 54" PML chute. A 60" spherachute would work, as would the larger PML chutes, but you might be in for a hike if it's breezy. How hard of a surface will you be landing on, and how high of an altitude is the launch site?

 

[bobkrech]

Hello,
I am building a 1/4 PML Patriot. I plan on flying it at high desert areas of Oregon which is a rather hard surface. The kit came with a 48" nylon chute with a center spill hole. This will allow for a faster decent that may cause a problem on harder landing surfaces.

I would appreciate any recomendations of any appropriate chute size and brand to use as a replacement. I plan on flying it single deploy without the piston ejection.

Rich

For a reasonable estimate use the descent rate calculator at http://www.rocketreviews.com/tool_descent_rate.shtml which accounts for parachute shape and altitude.

If we assume that the burnout weight of your rocket is ~5 pounds, and the base altitude is 4000' ASL, you want a 72" round (flat) chute or a 48" spherical chute to land at 15 fps. A round 54" chute or a 40" spherical chute will give a 20 fps landing speed under the same conditions.

Bob

 

[hardinlw]

You really do need to take into account the parachute shape. The TARC team I mentored last year started flying using a 27" flat chute they "borrowed" from my Viper IV. It came down too fast. They ultimately ended up using a 16" Fruity Chute which was just right. The Fruity Chute is an ellipsoidal chute which has a drag coefficient twice as high as a flat chute. Spherical chutes are similar. Other chutes are conical and have a different descent rate (drag coefficient) for a given size. It's pretty important to use a descent rate calculator that takes the shape into account. If available volume is a concern, you definitely want a spherical or ellipsoidal chute.

 

[cjl]

Agreed - the Spherachutes I suggested (as the name would imply) are hemispherical, and would result in a lower descent rate than the same size PML (conical) chute. Both will descend slower than a flat chute.

 

[mikec]

Hello,
I am building a 1/4 PML Patriot. I plan on flying it at high desert areas of Oregon which is a rather hard surface.

I've flown mine in the California desert with the stock chute and not had any problems, but you could always just go up a size as PML suggests.

The rocket does come in rather heavier than PML states -- mine weighs 63 oz without motor.