How fast should the rocket come down

[highflyer1968]

I have just started the build on a 4 inch frenzy with AV bay and i am wondering how fast should this rocket come down? With a 18 inch drogue it sims at 70 feet per sec and a 70 inch main sims at 20 feet per sec. The weight so far is 113 oz with motor. Are these speeds okay? Should speed be slower under main?

 

[Zeus-cat]

20 feet per second is great

 

[OverTheTop]

Those are the sort of numbers I would be happy to fly with.

 

[teepot]

I think it depends on what your landing on. I think most of the chute calculators recommend 15 FPS landing. If your landing on grass 20 FPS might be ok. I shoot for 13 FPS because we fly off a dry lake bed that is hard as concrete. At home 15FPS works because the ground is softer. You can look at "Parachute Size" calculator and put your information in and get a recommendation for three different types of parachute.

 

[GalantVR41062]

I have a 4" frenzy with a 54mm mmt, I plan to use a 18-24" drouge and the TFR 70" main I used for my L2 flight. I was hoping for 60 fps on drogue and 18fps on main landing on sod.

 

[heada]

9.8 m/s/s Anything more would be outta this world!

 

[highflyer1968]

Thanks for some ideas everyone. I will be doing a little more checking.

 

[TimothyG]

100 fps or more on drogue, less than 20fps for landing. This is rocket-dependent. Some of my more single-use oriented rockets I tried to land at less than 40 fps.

 

[JohnCoker]

I think it depends a lot on the surface. I agree with TimothyG's post, but I would drop the main descent speed to more like 15fps on the desert playa. (That's a huge benefit of dual deployment.)

 

[highflyer1968]

Im playing with rocksim and it really doesnt change the main velocity at all from 72 to 78 inch main. Still 20 feet per second. But when I change to a 96 inch it give me a velocity under main at 16 feet per second. That seems like its two big for this rocket. Also looking at fruity chutes and wondering why this chute shows 15 feet pr scond for a 7 lb rocket and its half the size?

 

[teepot]

Fruity chutes have a high CD. 2.2 I think. The Top Flight Crossfire is 1.35 to1.55 CD. The style and type have a lot to do with descent rate. Some chutes have a CD of .97 and others .75. So its not apples to apples.