Super Batray for my L1 - advice and tips welcome!

hey guys, high school senior rocketeer here. Normally I build scratch rockets for fun, but this summer I wanted to attempt my L1. I bought a smaller rocket kit (can launch upto F) sort of as practice, and then built this baby.


I'll be going for my L1 on Oct 3 at Geneseo, NY. pretty excited about it! didn't grab too many pictures during the build but thought I'd post what I got. advice for my launch is greatly appreciated!



There were a buncha rockets in the 70-100 price range (CDN) that all seemed really similar to me (3-4 feet, 38mm). but the batray's fins had me like.. :headbang:

Second pic is after primer...I have no idea how to do custom decals, so I went ahead and taped on a maple leaf. turned out pretty good, i gotta say...some blemishes you can't see in the pictures, but it's not too noticeable.







i'm young, so I'm pretty broke. lol. I wanted one of those aeropack retainers but for 35 bucks they weren't worth it for me. this on the other hand, was about 2 dollars. even though I can't think of how it would fail, i'm a bit nervous about it since it hasn't been tested.


this is the finished product.




excited for my launch on oct 3! will probably be popping an H143 Smokey Sam on it, 247Ns of impulse. if anyone has any advice for my L1 or rocketry in general, I'd love to hear it.


if anyone here has launched a Batray before, what has been your experience with the delay? does apogee normally line up with the simulation's calculations? I'm thinking for the H143 (1.4s burn), I'll put a 6s delay for an ~8s apogee shown by openrocket.

That paint looks great! I have the same rocket, and I always add about a half gram to a gram of BP just to be sure. Your 6s delay sounds about right for that H. I have flown mine on an I-195 and an I-180, both great flights.

Tips... Always ask if you're wondering. Even if you're not wondering, ask anyway. I ask the guys at my launches constantly, even when I'm pretty sure that o know what I'm doing. Two reasons: 1) I'll be sure that I have the right setup, and 2) guys love being asked for help, so my asking makes them feel good because everyone likes to be asked for advice

I got my level one with the same rocket. I got a lot of help from the guys at the launch. The most important tip was to add exrta black powder to the ejection charge. The 4" Batray has a pretty big internal volulme.

That aft retention is fine. I did the same thing after reading Modern High Power Rocketry 2. The Aeropack retainers are amazing, and I have used them on 3 rockets since then, but my first L1 attempt had bolts and washers and they held for 2 flights with no issues...then I lost it in the desert.

I just recently got my L1 finally, so I guess in terms of general advice, I have learned a few basic things to never forget:

1. Don't use elastic shock cords. I have heard that sometimes they fail, which I believe. Also, even if they don't fail, people will give you dirty looks and criticize your decision to use them, which is no fun, so just drink the kool-aid and stick with kevlar harnesses.

2. Make sure your delay is set correctly. If you aren't absolutely 100% sure you are using your delay adjustment tool correctly, ask for someone for help, or at least to look over your shoulder.

3. Secure your igniter well. I haven't even been doing this that long and I am already tired of hearing "Spit the igniter, gonna have to recycle that one" from the LCO. Cap, tape, or both, just make sure that sucker stays in there when they push the button.


Your rocket looks great, good luck!

Brian

thanks for the tips, especially on the black powder. didn't know about that.

does adding extra black powder change how i would set up the delay? as in, would i have to drill any deeper or anything like that to make up for the extra BP?

mine flies nicely on an AT H148R with an 8sec delay. note burn time does not get added to the delay, the 8 second delay means 8 seconds after motor burn out. what does your bird weigh? mine weighs in at just under 61 oz(and OR says 8sec delay).
shock cord; either get a shock cord protector or use Kevlar it is a real pita to reach in to remove/replace the stock nylon after it burns through.
Rex

L1 here as well in the naked Super batray H115DM - 8 sec.... Was 1.5 sec too long and coming back in ballistic when ejected but no damage, so passed. Went to approx 1100' - I've also flow on H115, H182, H152, H195, and I-140 a great choice and should get a little whistle from the fins.

I have not added extra BP to any of my 9 flights prior to extending and going DD but am using 1.2 grams for my ejection charges now so I like that suggestion as well.

My future flight since now heavier with DD and extended have to be a little stronger as an H195 only goes to 900'.

Your retention will be fine.


Great looking job by the way! Post a pic or video when your done

maherakhtar said:

thanks for the tips, especially on the black powder. didn't know about that.

does adding extra black powder change how i would set up the delay? as in, would i have to drill any deeper or anything like that to make up for the extra BP?

Click to expand...

Nothing changes about drilling the delay. To add BP to a CTI motor, just pour it directly on top of the paper cap and tape over it with some masking tape. Just be sure to keep the tape off the sides of the liner so you can still get it in the case!
Good luck and post video if you can

Nick@JET said:

I've also flow on H115, H182, H152, H195, and I-140 a great choice and should get a little whistle from the fins.

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thats a pretty sweet pic of yours. what delay did you use for the H195 and H152? i've yet to measure and weigh mine, so i'll be doing that soon then redoing the sims.

i also don't have a shock cord protector (nylon shock cord). unfortunately both ends are tied down really strong and i won't be able to slide it on normally...what do you guys recommend i do? I could slit one side and re-stitch and CA glue it back together.

Every thing looks good and the advice you've gotten is right. The only thing I would suggest is that once you've got the motor case and test fit it, cut those threaded rods down that you are using for retention. If they are too long, they can get bent on landing and then you'll have a hard time getting the nuts and washer off and the motor case back out. You could retrofit the aft CR with threaded inserts and may have to if the rods get bent.

For future builds, you can check the forum here for methods and materials, but I would highly recommend putting threaded inserts in the aft CR and use screws for retention instead of the threaded rods. If nothing else, screw heads will dent a car roof or truck cap but those rods will leave holes making it look snakebit.

maherakhtar said:

thats a pretty sweet pic of yours. what delay did you use for the H195 and H152? i've yet to measure and weigh mine, so i'll be doing that soon then redoing the sims.

i also don't have a shock cord protector (nylon shock cord). unfortunately both ends are tied down really strong and i won't be able to slide it on normally...what do you guys recommend i do? I could slit one side and re-stitch and CA glue it back together.

Click to expand...

8 sec any longer and will be ballistic and risk zipper damage .

I still run stock nylon line with mine and no protection near ejection charges (but nomex blanket for the rest - I put a lot of dog barf in while I'm holding the line up so it's completely covers the line. Not perfect but has served 11 flights with very little scorching or damage. Prefer a cord Protection though.
Good luck with your cert!

Good advice also on the retention screws instead of rod.

For future reference, Mad Cow Rocketry has a great and inexpensive retainer that works close to the way you have yours set. $9.95. Nice thing is that it can be installed after you've built your rocket. I am also building a 4" Batray right now (Look at the thread, "Some Days, You Just Can't Get Rid of a Bomb.") and I am using this device for motor retention.

https://www.madcowrocketry.com/motor-retainer-38mm/

Is this single or dual deploy? If it is single, and you're not afraid of doing some cutting into the airframe after completed, you could make it DD and use it for your L2. Cut the airframe no more than 10.5" from the forward end and that is where you insert your AV Bay. Again, this is what I am doing. That way I can stick 6xl motor ases in it. I want to fly it on a J150 MY.

thank you for the advice on the rods! i'll be sure to do that...might have to by a bolt cutter once i cross the border though, since i doubt they'll let that through.

Nick, did you use 8s delay for all of your motors? i think i'll go with a a fair bit of wadding to protect the cord. usually i wrap the cord in wadding, and then a throw in some extra crumpled pieces.

that looks like a great inexpensive retainer, will definitely consider it for my next HP rocket! mine is single deploy right now, but i'm considering modding it for DD later on...but that won't be for a while lol.


again thanks everyone for all the help,it's much appreciated!

Yes I used 8 sec for all based on suggestions at the field. Which on all flights ejection happened passed apogee - AT H115 DM being the worst, so in hind site I should've gone 6 sec (7 sec not an option unless you have a thinner washer then what comes with AT delay tool I guess).

Also I don't think I but mine very heavy, except for 1 quick link, swivel, 38mm option with Aeropack retainer and 29mm adapter, oh and 12" nomex blanket - no nose weight and flew naked - so 6 sec should've been my number (I never checked OR at that time). Sorry I don't have my original weight and now added DD and payload extended tube.

When and where is your flight planned for?

i might have to adjust my centre of gravity. the instructions on the batray say that the CG has to be at or in front of a certain point. i simulated my rocket configuration during launch; one with recovery wadding and one without.

the one with recovery wadding, which is what i'm likely to do, (i still pushed the wadding down a bit) had the CG millimetres in front of the specified point. the one without recovery wadding had the CG millimetres behind the specified point. both were ridiculously close...essentially I was at the specified point.



can anyone give input? i'm inclined to add a bit of weight to the nose cone, since i'm not exactly going for any kind of maximum height and just want maximum stability. but then again, according to the instructions, i'm "at or in front of" the specified point when i simulate launch conditions.

Nick@JET said:

Yes I used 8 sec for all based on suggestions at the field. Which on all flights ejection happened passed apogee - AT H115 DM being the worst, so in hind site I should've gone 6 sec (7 sec not an option unless you have a thinner washer then what comes with AT delay tool I guess).

Also I don't think I but mine very heavy, except for 1 quick link, swivel, 38mm option with Aeropack retainer and 29mm adapter, oh and 12" nomex blanket - no nose weight and flew naked - so 6 sec should've been my number (I never checked OR at that time). Sorry I don't have my original weight and now added DD and payload extended tube.

When and where is your flight planned for?

Click to expand...

october 3rd, Geneseo NY. i'm thinking of 6 seconds but i haven't re-run the simulations yet with the adjusted CG and weight specific to my batray....initially it said 8 second apogee, so with a 1.4s burn, i think 6 should be good.

Not sure how to post video - a have a video of L1 H115 and I-140 only to just passed motor burnout so won't really help much but if you want PM me your email or cell and I'll send them to you.

For what it's worth I didn't add nose weight and some wadding really won't affect CG . All boosts have been arrow straight from H115 through the I-140. However I have just cut the nose cone to install bulkhead and tracker and will add weight so I can fly on J's since changing to DD and tracker. I'm thinking of all thread and washers up in the nose cone as an adjustable- removable weight system

no worries about the video. i hope to fly mine on larger engines in the future, so if the CG is already at an iffy spot on mid-H motors, then i think i will add some weight to the nose cone.

added about 130g total to the nose cone. used shot, coated with polyurethane glue, anchored by a wooden dowel. L1 attempt in just a few days!

Got my L1! Everything went great, thanks to all those who helped me out. will post a video soon.

Congrats on the Cert!!!

thanks!

here's the video [video=youtube;0do_Tj4K8m0]https://www.youtube.com/watch?v=0do_Tj4K8m0[/video]

Congrats on your cert!
Great job on the rocket!

Congratulations LEVEL 1...achieved - very cool!
Enjoy the ride!

thanks everyone!

unfortunately, cutting the rods wasn't the best idea lol. using bolt cutters caused the threading at the very end of the rod to be distorted. One of the rods works as long as you have a nut driver, but for now the other one doesn't work even with a nut driver.

kinda lost as to how I should fix this. maybe some really coarse sandpaper, and sand off the threading entirely for the first millimetre of the rod? for now i'm not going to touch the rod that is working until i can get the other one totally fixed.

maherakhtar said:

thanks everyone!

unfortunately, cutting the rods wasn't the best idea lol. using bolt cutters caused the threading at the very end of the rod to be distorted. One of the rods works as long as you have a nut driver, but for now the other one doesn't work even with a nut driver.

kinda lost as to how I should fix this. maybe some really coarse sandpaper, and sand off the threading entirely for the first millimetre of the rod? for now i'm not going to touch the rod that is working until i can get the other one totally fixed.

Click to expand...

I'm sorry you used a bolt cutter. The way I usually cut something like that is to thread a nut onto the rod, cut it with a hack saw or Dremal and cutting wheel and then when you turn the nut back off, it straightens out any messed up threads.

I know that doesn't help after the fact, but filing, grinding, sanding the threads to eliminate the bend and distorted parts can usually get things working again.

at least i know for next time lol. thanks!

CzTeacherMan said:

Tips... Always ask if you're wondering. Even if you're not wondering, ask anyway. I ask the guys at my launches constantly, even when I'm pretty sure that o know what I'm doing. Two reasons: 1) I'll be sure that I have the right setup, and 2) guys love being asked for help, so my asking makes them feel good because everyone likes to be asked for advice

Click to expand...

Then you have the guys like me, who love to blab, even if it is only online!

maherakhtar said:

thats a pretty sweet pic of yours. what delay did you use for the H195 and H152? i've yet to measure and weigh mine, so i'll be doing that soon then redoing the sims.

i also don't have a shock cord protector (nylon shock cord). unfortunately both ends are tied down really strong and i won't be able to slide it on normally...what do you guys recommend i do? I could slit one side and re-stitch and CA glue it back together.

Click to expand...

Honestly I would not worry about it for your first few flights. If this becomes a favorite and you start flying it at every launch you go to, or you start to see damage in your pre flight inspection, you can still drill from the bottom up and run a stainless steel line for attachment.