Risk of high g-forces?

[Velocity Aerospace]

So I'm working on my 2nd L1 attempt, and I need to buy my motor tomorrow... the problem i,I was going to get an I175, but they're sold out. My next best Sim was with the H550, but my rocket would reach a peak acceleration of 20 g's. I have an easymini and split 4k as payload, and was wondering how risky it is to launch something with that high if an acceleration. Urgent responses would be great. Thanks to all

 

[OverTheTop]

I wouldn't be too worried about 20g's. That is reasonably tame. I would be making sure the SD card in the camera will stay latched into the socket.

Just remember that everything in the rocket will weigh 20 times what it normally does. If it can take that sort of force there should be no problems.

Also consider that you are looking only at boost forces. The ejection forces can be much shorter and sharper than when under boost.

 

[Velocity Aerospace]

I wouldn't be too worried about 20g's. That is reasonably tame. I would be making sure the SD card in the camera will stay latched into the socket.

Just remember that everything in the rocket will weigh 20 times what it normally does. If it can take that sort of force there should be no problems.

Also consider that you are looking only at boost forces. The ejection forces can be much shorter and sharper than when under boost.

Thanks. I did consider ejection forces, and the burn time on the motor is only .6 seconds, so it shouldn't be too bad. Especially considering it's peak acceleration, not average. My first attempt didn't go well, so I want to do everything I can to make sure this one goes right.

 

[OverTheTop]

What happened the first attempt?

 

[Neutronium95]

High acceleration is not really a problem. High airspeed is what kills rockets.

Just make sure that all of your electronics are solidly mounted to a sled and it'll be fine. At BALLS last weekend I had a flight that exceeded 100g, and the batteries were secured with VHB tape. It held just fine.

 

[Velocity Aerospace]

What happened the first attempt?

I think what happened is I over-tightened the bulkheads in the coupler, mushrooming it out so when the charges fired, the rocket couldn't separate, causing it to lawn dart. Along with knowing not to do that, I also shortened the coupler by an inch on both ends so that there's 2 inches of meat instead of 3 so it shouldn't take as much force to deploy the chutes

 

[Steve Shannon]

I think what happened is I over-tightened the bulkheads in the coupler, mushrooming it out so when the charges fired, the rocket couldn't separate, causing it to lawn dart. Along with knowing not to do that, I also shortened the coupler by an inch on both ends so that there's 2 inches of meat instead of 3 so it shouldn't take as much force to deploy the chutes

Did you ground test your deployment charges?
Shortening the coupler by an inch on both ends really isn’t a common way to reduce the force needed to deploy your chutes. Once the ejection charge goes off, if the body parts start separating that extra inch of travel is inconsequential. Generally speaking the amount of coupler that is inserted should be about the same as the body tube diameter or slightly more, for a joint that comes apart.
Was the coupler hard to insert into the body tube when you prepared the rocket?
What was the material used for the body tube and coupler?

 

[Velocity Aerospace]

Did you ground test your deployment charges?
Shortening the coupler by an inch on both ends really isn’t a common way to reduce the force needed to deploy your chutes. Once the ejection charge goes off, if the body parts start separating that extra inch of travel is inconsequential. Generally speaking the amount of coupler that is inserted should be about the same as the body tube diameter or slightly more, for a joint that comes apart.
Was the coupler hard to insert into the body tube when you prepared the rocket?
What was the material used for the body tube and coupler?

So I did do ground tests, and everything worked great. Come the day if the launch, I had a lot of voices giving advice, and I got flustered and tightened the bulk heads too much. I did have a hard time getting the sections together, but with enough baby powder, we got it to work. (Lessons for next time). The coupler and airframe were 3" fiberglass. The shorter section may be inconsequential, but my thought process was to just reduce the static friction the charge needs to overcome

 

[tsmith1315]

The coupler and airframe were 3" fiberglass.

Is your new attempt glass as well?

 

[Velocity Aerospace]

Is your new attempt glass as well?

Yes. Except for a few changes, the rocket is identical

 

[NTP2]

I once had my lance deta max at 100Gs it will be fine.