New Member with some construction questions

[achaskin]

Hello fellow rocketeers,

I have been reading the forums for years now and have found all the answers for my LPR builds. I am now starting my High Power certs so my first build is an Aerotech Mega Initiator. It wasn't difficult like is expected, just a lot of new methods that didn't apply to lower power builds. I have a couple questions reguarding sanding my epoxy fillets and subsequent damage to the cardboard airframe, as well as the finish on the paint. I would go ahead and post specifics and pictures but I don't want to spam in the wrong place. Where is the proper place to post these?

Any advice is appreciated,
Thank you

Achask

 

[neil_w]

Welcome!

I don't think anyone would get too bent out of shape if you posted the pictures here, but if you really want to go to the "right" place, it would be either the HPR or Techniques forum.

 

[Huxter]

Welcome to the forum!

I, too have only made LPR, and want to go bigger, higher, faster!

I'd be very interested in your builds - good luck!

 

[Zeus-cat]

Instead of sanding epoxy fillets, you should use techniques to make fillets that don't need sanding.

One method that works well is to lay down masking tape on the fin and on the tube to keep the epoxy confined to the fillet area. Lay epoxy in and then use a Popsicle stick (eat Popsicle first!) to smooth out the epoxy. Lift the tape once the epoxy sets, but before it dries. Practice on some scrap pieces first.

 

[achaskin]

Welcome to the forum!

I, too have only made LPR, and want to go bigger, higher, faster!

I'd be very interested in your builds - good luck!

Thank you, I made a thread titled “Cardboard tube damage & High gloss finish” with some pictures and I will post updates there on the Mega Initiator build if you’d like to check it out!

 

[achaskin]

Instead of sanding epoxy fillets, you should use techniques to make fillets that don't need sanding.

One method that works well is to lay down masking tape on the fin and on the tube to keep the epoxy confined to the fillet area. Lay epoxy in and then use a Popsicle stick (eat Popsicle first!) to smooth out the epoxy. Lift the tape once the epoxy sets, but before it dries. Practice on some scrap pieces first.

I probably should have left them alone since they were so smooth. I was really trying to sand the tiny raised edges where the epoxy met the tape. Probably wasn’t worth it in hindsight. Now I’ll need to patch it up with some hi build primer…

 

[beeblebrox]

Hello fellow rocketeers,

I have been reading the forums for years now and have found all the answers for my LPR builds. I am now starting my High Power certs so my first build is an Aerotech Mega Initiator. It wasn't difficult like is expected, just a lot of new methods that didn't apply to lower power builds. I have a couple questions reguarding sanding my epoxy fillets and subsequent damage to the cardboard airframe, as well as the finish on the paint. I would go ahead and post specifics and pictures but I don't want to spam in the wrong place. Where is the proper place to post these?

Any advice is appreciated,
Thank you

Achask

A kit is definitely the way to start as the main thoughts for HPR have been worked out already. Fly a couple G Motors first to get ideas on how high the beast will fly. For your cert flights remember the golden rule of cert flights. KEEP IT SIMPLE. Go Relatively big. Use the smallest motor available for the category. You must buy the motor at the field where you intend to fly the cert flight. For Level 1 I recommend a 4" Rocket at least 6' tall. Use a short burn low end H-Motor. (For a Nice straight boost) Like an AeroTech DMS H182R -8. I have seen too many people try to fly a small rocket with an H for lvl 1 cert only to lose it and fail out. Go for broke after you get certified... For LVL 2 Again go big. A 5.56" dia LOC kit would be perfect. Use electronics for ejection. There are many options for that and they don't break the bank. ) Eggtimer Apogee is $15 for the kit + $5.00 for the battery pretty easy kit to assemble with basic soldering skills. There are options for paid services for assembly too. (You need to get a charger for lipo's) Spend the money for heavy duty kevlar shock line especially for rockets over 3.3 lbs. If you kit came with elastic shock line, don't use it. Use a piece of 1000lb test kevlar line about three times the length of the elastic line the kit may have come with. About twenty feet of line for a 4" rocket.

Look at this Apogee magazine article too...

https://www.apogeerockets.com/education/downloads/Newsletter282.pdf
Source of kevlar line in different sizes... https://www.emmakites.com/collections/line-accessories


No issues with posting photos here. Your answers will be all in one place rather than being mixed up in another thread...

 

[beeblebrox]

...when you use up the Emma Kites kevlar, don't throw the spool away, make a rocket out of it...

 

[afadeev]

I probably should have left them alone since they were so smooth. I was really trying to sand the tiny raised edges where the epoxy met the tape. Probably wasn’t worth it in hindsight. Now I’ll need to patch it up with some hi build primer…

Museum-quality epoxy fillets are largely a form or artistic expression, that is not required for actual flight-worthiness.
As long as the fins are held on tight, and straight, fin fillets just add aerodynamic perfection and extra strength to insure against transportation damage.

Instead of sanding epoxy fillets, you should use techniques to make fillets that don't need sanding.

Indeed.
Sanding epoxy fillets is a royal PITA.
The only thing that's worse is sanding fully cured fillets that were formed from epoxy putty - those turn into granite.

If the appearance is really a priority for you, just scuff the existing fillets with 60-grit sandpaper, and apply another layer of (hopefully smoother) fillets over the top!

Thank you, I made a thread titled “Cardboard tube damage & High gloss finish” with some pictures and I will post updates there on the Mega Initiator build if you’d like to check it out!

I could not find your other thread, feel free to post a link in this one.
w.r.t. carboard tube scuffing while sanding, usually it's not a big deal. If you are worried about structural integrity or surface roughness, brush a layer of thin CA or epoxy over the scuffed areas. This will both harden the material, and make it easier to sand and finish aftewards.

HTH,
a

 

[teepot]

I probably should have left them alone since they were so smooth. I was really trying to sand the tiny raised edges where the epoxy met the tape. Probably wasn’t worth it in hindsight. Now I’ll need to patch it up with some hi build primer…

Try spraying the filet with alcohol and then smooth the filet with your finger. You can also blend the filet to the shape of the fin. If no spray bottle just dip your finger in the alcohol. Wait for the epoxy to set awhile before doing this. When it's firm but still pliable. The smoothness is also dependent of what you use to make filets.

 

[achaskin]

Museum-quality epoxy fillets are largely a form or artistic expression, that is not required for actual flight-worthiness.
As long as the fins are held on tight, and straight, fin fillets just add aerodynamic perfection and extra strength to insure against transportation damage.



Indeed.
Sanding epoxy fillets is a royal PITA.
The only thing that's worse is sanding fully cured fillets that were formed from epoxy putty - those turn into granite.

If the appearance is really a priority for you, just scuff the existing fillets with 60-grit sandpaper, and apply another layer of (hopefully smoother) fillets over the top!



I could not find your other thread, feel free to post a link in this one.
w.r.t. carboard tube scuffing while sanding, usually it's not a big deal. If you are worried about structural integrity or surface roughness, brush a layer of thin CA or epoxy over the scuffed areas. This will both harden the material, and make it easier to sand and finish aftewards.

HTH,
a

Below is the link for the thread in which I've been posting updates. Final coat of primer and paint is next, then to create the SIM and choose a few motor options. I've also been considering getting a tracking device for this project. For its first flight it may not go so far as to dissapear down range, but I'd like to make sure I pass my first attempt (no chance of losing the rocket) as well as prepare for its next flights which will be higher and higher. This kit is currently mid separation (single) but even when I decide to switch to DD, it will still have almost a foot and a half of payload space. EggFinder seems to be the best option for its price, since I am pretty well rehearsede in soldering. I don't want it to be overkill but I also feel I wouldn't be doing enough with just a piezo "buzzer".
I want to have reliable tech for this first launch that can be up cycled or modified for more advanced future flights. What do y'all suggest?
https://www.rocketryforum.com/threads/cardboard-tube-damage-high-gloss-finish.168100/Again, thanks everyone for the help. I can't wait to see the rush of answers when I bring up what type motor to use!!!

 

[afadeev]

I've also been considering getting a tracking device for this project. For its first flight it may not go so far as to dissapear down range, but I'd like to make sure I pass my first attempt (no chance of losing the rocket) as well as prepare for its next flights which will be higher and higher.

Don't overthink it.
For most H-motor L1 flights, you will be going somewhere between 800-1,500 feet on a 4" airframe. Anything below 3K in altitude is easy to follow with a naked eye (unless there is a low cloud cover, in which case, wait a bit).

I love GPS trackers and enjoy building them as much as flying them (http://eggtimerrocketry.com/), but there will be time for that later.

I want to have reliable tech for this first launch that can be up cycled or modified for more advanced future flights. What do y'all suggest?

If this your first HP rocket, keep it simple. Unless you enjoy building more than flying.

Finish the rocket, fly it, get your L1 cert.
Have fun doing it.
THEN decide what you want to do next.

a