3" Home built

[murietamike]

I had some stuff laying around so I built this. It's 53" tall. 2- 3" Body tubes. I built a 4 -24mm cluster mount. It has 4 Aerotech F32-8T in it. According to Rocksim it should top out at about 2300 FT. I did put a ejection baffle in it. I've added this RUNCAM2 and Apogees simple gps tracker. My concern is will this fly straight or be pulled over to the camera side? The camera and housing weigh bout 97 G /3.4 OZ. The tracker transmitter weighs about 82G/ 2.9 OZ.

Thanks for your time.
Mike

 

[loopy]

I don't think the camera will cause it to sway too much to the side during flight...

 

[loopy]

WHat's the fully loaded weight on this? I think you're good on NFPA with everything else for this to be a class 1 rocket, but what's the overall weight?

 

[murietamike]

Overall weight is 984 G /34.65 OZ.

 

[loopy]

Cool. I’d say you’ll be fine. The camera shroud might pull it over some, but as long as all the motors light up at the same time and you’re not launching in high winds you should be fine.

 

[Handeman]

If you are launching at our club, BattlePark you would not be allowed to launch until you installed 1010 rail buttons. Those 4 F32-8T motors puts the total impulse in the H range at 228 Ns and for safety reasons, we do not allow any HPR rockets to launch from rods, only rails.

 

[murietamike]

Thanks for the advice. I was hoping the Estes Ps II with a 6 foot 1/4" rod would hold it. I'll look into the rail system.

 

[Handeman]

Thanks for the advice. I was hoping the Estes Ps II with a 6 foot 1/4" rod would hold it. I'll look into the rail system.

It would probably work fine. No HPR rockets on rods is our club rule to reduce risk to our club. There is no requirements that I know of in any safety or NFPA codes that specify the type of launch rods or rails that can or can't be used.

 

[fyrwrxz]

Beat me to it. Saw the lugs and went nope!

 

[murietamike]

What is wrong with the lugs?

 

[DaHabes]

What is wrong with the lugs?

You have to worry about 1) rod whip; 2) off center thrust if all four motors don't light up, which is a bitch on a rod (not stiff enough), it could bend the rod over and take off at a bad angle or hang up on the rod, with very unpredictable results; 3) rod length (probably not an issue with 4 F32's, but I refuse to use less than a 6' rail on ANY high power launch).

 

[Handeman]

What is wrong with the lugs?

There is nothing "wrong" with lugs. Back in the day, HPR were launched on 1/4" to 1" rods. The problem is the unpredictability and safety issues associated with rod whip. I've seen the tip of a 1/4" 6' rod whip over a foot to the side and the rocket leave at a 45 deg. angle. The direction is random and unsafe for people and the rockets.

If you want to use rods and lugs, check with any club you want to launch with and find out their rules. My club does not allow any HPR launches on rods. We highly discourage G motor from being launched on rods and suggest rail buttons for F motors also.

 

[kenstarr]

I picked up an old NCR rocket from the current owner North Coast Rocketry... Sweet looking rocket with ancient decals. It had 1/2 lugs on it so as part of my upgrading the paint job, I pulled those pesky lugs and threw on some buttons. Not too hard to do. Some of my earliest builds had lugs mainly because I didn't know any better but I've swapped them out for buttons as well. Heck, add some buttons on the other side of the rocket and you can have both worlds!
Ken

 

[dr wogz]

I hear it is becoming the norm, that all rockets with G impulse or more are to have buttons..

 

[murietamike]

Thanks for all of the input. I've looked around and the least expensive route seems to be a diy rail launch pad on Apogee rockets site. https://www.apogeerockets.com/education/downloads/Newsletter235.pdf
He didn't mention or I'm not seeing it, the rail length. Although he is using 3' of 1 1/4 pvc for the center mast. If I buy 2- 10' 1 1/4" pvc, that would give me the 4 - 3 footers for the legs and 7' for the center mast. My ultimate question is do I need an 8' rail? Or will 6' suffice. Thanks again.

 

[waltr]

6 foot 1010 rail is good for most rockets. If TTW is 5:1 then good. If TTW is lower than you may need a longer rail.
Do sims with different rails lengths to get speed off rail to be sure. And remember that the sim rail length is typically the distance from the Top button to top of rail.

 

[tsmith1315]

I've looked around and the least expensive route seems to be a diy rail launch pad on Apogee rockets site.

I use a 1010 rail from here (free shipping makes a big difference). If you have a Grainger nearby for local pickup, that might be easier:

https://www.govets.com/80-20-310-61984951.html

Also, heavy old camcorder or lighting tripods make good bases. You can pick them up a thrift stores or yard sales for next to nothing. These two were no more than $5 each.

 

[murietamike]

Nice. I went ahead and ordered the 1010 8 footer. Shipping sucked. Got some buttons ordered and will grab some pvc from Lowes. Think I'm ready.
Thanks again

 

[SDramstad]

Even my mid and low power builds use mini and micro buttons. Much better then lugs.

 

[murietamike]

I like that. What kind of set up do you have for the smaller rockets?