Questions On My First HPR Build

[Terry_TBR]

I am just finishing up building a PML Quantum Leap II (my first high power rocket) that I am flying in a few days. It is actually a test bed for an electrical payload that I designed for my senior design project. Due to order delays and some items being back ordered I only had a week to assemble the rocket. While that might be easy for experienced builders, for someone who hasn't built anything beyond Estes kits it was a little intimidating! I've been documenting the build on a blog I set up at http://www.tbrocketry.com if anyone is really curious.

I am planning on this weekend not only being the testing of my electrical package but also my level 1 certification through NAR. The first launch will use the MAWD to verify the rocket is good before adding in my experimental electronics.

I've got a few little things I still need to figure out and was hoping to get some insight from those of you who've got it all figured out!

Drogue Parachute vs Drogue Streamer

The Quantum Leap II kit came with two parachutes; a 30" chute for the booster stage and a 48" chute for the sustainer stage. I will only be flying the rocket in a single stage configuration this weekend so I'd like to use a drogue and a main. Is the 30" chute too large for a drogue? Could a large streamer be used and, if so, what size would be best?

The area that the rocket club uses to fly is surrounded by trees and heavily overgrown fields... so I would really like to keep the landing as close to the pad as possible... RockSim put the max altitude around 7700' with the J415WL motor but I cannot simulate the descent since I am using the free trial. So there is my big concern... is the 30" chute too big for a drogue and will cause major drift?

Motor Retention

I've seen the commercially available motor retention methods but I doubt I could get any of them in time for the launch. Is there a good home brew method for motor retention that I can implement for this weekends launch and then get a better commercial solution for future launches?

School Me!!

You guys have been around the block a few times... I am just stepping out of the door... any advice, tips, tricks, criticism, etc. that you could share based on this project?

I appreciate any insight or information on this...

[Pantherjon]

First off, welcome to TRF Terry! :D Nice looking rocket there! Will answer a couple of your questions..

Drogue chute or drogue streamer: I always go drogue-less..Much less drift that way..And have the main come out at 700 feet..

Motor retention: Pretty simple..A couple of threaded inserts, a few 'spacers', a couple of screws and a couple of washers..Total cost of parts is ~$5 :D Attached pictures show how it is done- my 3" Thor(38mm hole)

[DAllen]

Lotsa good questions here...


Is the 30" chute too large for a drogue? Could a large streamer be used and, if so, what size would be best?


Yes, 30" seems really large for a drogue. I build a PML IO which a lengthened and modded for DD and used a 12" x-form chute for my drogue. I secured the chute about 1' away from the upper section and worked perfectly. I have also used a streamer for a modded LOC Weasel for dual deploy with success.

The idea of a drogue is to keep the upper section high enough so that when the main deploys it won't get wrapped up in the lower section. Also, you need a drogue to prevent the rocket from becoming ballistic which can happen on drogueless setups.



Is there a good home brew method for motor retention that I can implement for this weekends launch and then get a better commercial solution for future launches?


One thing that can be done is to buy some threaded rod - I use 6/32. Drill a hole slightly bigger than the rod. Load up the rod with epoxy and insert it into the hole. As far as length goes, I would stick as much rod in as possible leaving at least 1/4" longer than how much your motor sticks out so it looks like this:

Billy Bob Joe Scratch Build (http://www.rocketreviews.com/reviews/all/scratch_billy_bob_joe.shtml)

About half way down the page you will see how this works. Be sure not to get epoxy on the portion of the rod that sticks out. It's very effective and I have used it on most of my MPR and HPR rockets. I've seen guys at our launches with J's use this same method effectively.

One thing to consider is that you are doing this after the rocket is put together so you want to make absolutely sure the epoxy gets a good bond to the MMT tube. I would wait at least 24 hours after application and give the rod a good tug to make sure it is in place before using it. The big draw-back to this method is that you cannot store the rockets in the upright position without some sort of a stand.

Hope that helps.

-Dave

[RocketMonkey]

I am planning on this weekend not only being the testing of my electrical package but also my level 1 certification through NAR....RockSim put the max altitude around 7700' with the J415WL motor.

That is an L2 motor...if this is your L1 flight you need to keep it to an H or I motor.

[hardinlw]

Since this is your first high power rocket and you're trying to jump straight to dual deployment, I'm going to provide some information that you may already know or you may not have realized that certain questions even needed to be asked. Most people, myself included, certify level 1 with engine-based deployment just like the Estes rockets. I got my L2 with engine based deployment and only then moved on to altimeter-based deployment. The idea was not to introduce too many new concepts at once. Please don't be offended if you have already addressed all these issues.

As RocketMonkey said, the J415 is a level 2 engine. Not only that, it is almost a K. Look for a high thrust I engine like the I357 for a L1 cert flight.

You mentioned a MAWD and a drogue. From that, I assume you are using altimeter deployment. Is that correct? The drogue implies dual deployment (drogue at apogee and main at some lower altitude). Did you buy the rocket set up for dual deployment or did you modify it. In dual deployment, the drogue is usually at the aft end of the rocket and is deployed by blowing off a section consisting of the fins and motor mount. The main is in the normal location behind the nose cone. The altimeter is in an electronics bay in the middle. If the kit was not set up for dual deployment and you did not add this aft separation point, you can still use an altimeter, but it will have to deploy the main at apogee.

For altimeter deployment, you should use a plugged forward closure for the engine. In a pinch, you could use the standard closure and leave off the ejection charge, but if the delay charge burns through before apogee, it may still leak enough gas through the hole that would normally ignite the ejection charge to separate the rocket. The plugged closure is best.

A 12" or 18" chute is appropriate for a drogue, but it needs to be sturdy enough to handle the heavy rocket, so the plastic 18" chute from Estes is not one to consider ;-) . Some rockets use streamers and it is even possible to do "drogueless" if the rocket separates such that the two sections will fall in a horizontal orientation instead of going in nose first. PML uses an 18" drogue in their dual-deployment version.

Larry

[Terry_TBR]

Thank you everyone for the replies so far. I should have explained in a little more detail the whole picture that I am trying to accomplish.

I know that the J motor is way more than a L1 requires but I required the altitude that it would provide to meet the test requirements of my project. I actually got the Quantum Leap II so that I could fly it dual stage to get above 10k' but quickly realized I was getting way too far ahead of myself. So I tweaked my test requirements so that a single stage flight above 7k' would work.

The flights that I am planning to make consist of the sustainer stage, the payload bay section, and the nose cone. The sustainer stage will separate from the payload bay via a motor charge at apogee. I was going to attach a drogue or streamer on the shock cord close to the payload bay to keep it higher than the sustainer stage. Once the rocket passed through the configured altitude, the MAWD (first flight) or my electronics card (second and third flight) will ignite a black powder deployment charge that will separate the nose cone and payload bay. The main 48" parachute will be attached to the shock cord close to the nose cone.

Going drogue-less is a bit scary. If this thing takes a plunge then not only do I lose the rocket but I fail the course and don't get the graduate in December. So I am a bit nervous to say the least! So long as deploying the main after 6k' free fall will work fine and not damage anything then that would be the best option. It is supposed to be a little windy on launch day. I did buy a transmitter in case it drifts too far off but the 222.175MHz beam antenna I made to hook up to my ham radio doesn't do too good a job at fox hunting. So minimizing drift is an important goal.

I hope that clears up what I am trying to accomplish. Again, all the complexity was basically for meeting the requirements of my design. As it is I already reduced the requirements from dual charge firing to single charge firing and dual stage to single stage. So I will not be testing all the features of my design but I did the reduction in order for safety concerns and to raise the chances of successful flights.

I do have to admit that sometimes my ego makes me think I am more than capable of doing all of this on my first shot... but then reality sinks in and that is why I appealed to you guys so you could set my head on straight! :D

I will try to take a photo of everything laid out how I am planning on flying it and if I cannot get that done then I will make a drawing and post it. That will clear up any confusion if my description above was not suitable.

[rocketgroupmike]

Sorry Terry, but you can NOT certify NAR Level 1 with a J motor. I suggest you check the NAR site for the exact requirements...

[Handeman]

Terry,
rocketgroupmike is right, you can't use a J to cert level 1, it has to be a H or I motor. Then you can only fly the H & I motors.
What you can do is fly the rocket for it's test flight on a I motor to make sure your drogue etc. is right. Then take the L2 test and fly it on the J for your L2 and to test your electronics. It's a lot to do in a day, but if you're well prepared it is certainly do able.

[brianc]

Terry,

You REALLY need to talk with Gary Dalhke! He flys at SRA
and has several QLII of various sizes. He's a wealth of
knowledge. PM if you need his contact info.

Also, whatever your choice (drogue chute or streamer), put
a beeper on board. The SRA Rocket Ranch is an unforgiving
place.

I'm planning to head over to TTRA this Saturday, but I'd
love to see your bird fly someday.

[JJI]

the L1/L2 issue aside, which incidentally the other guys are exactly right about, if you use a drogue, the 30" chute may be too big. The main use of a drogue chute or streamer in an HPR project of your size is positioning, it's not necessary to slow down the rocket once it has separated into multiple parts. A 30" chute for that rocket deployed at apogee may cause it to drift waaaayyyyy down range, especially on a windy day. I would go drougeless, I do it all the time with my 4" Horizon, which is about the same size as yours.

[MaxQ]

From your build thread it appears that you have the Quantum tube kit....

Level 1 motor selections aside....

Is PML still warning about using Quantum tube materials for high performance flights...particularly .85 mach and over?

I have a QL II kit and haven't finished it because I want to replace the airframe with glassed phenolic.....just to avoid the possibility of watching it shred.


-------------------------------------------------------------------------

"Some customers have thought that QT is a replacement for ‘glassed phenolic. This is not the case. Quantum Tubing is not intended for super-high-stress applications. It is intended as a replacement for standard phenolic for sport rockets. QT makes it easier and faster for flyers to achieve a nice finish, and to eliminate some of the problems of plain phenolic in high-impact situations like landing on rocks, cold-weather flying, etc. ‘Glass-wrapped phenolic is still the best product for high stress flights"



-------------------------------------------------------------------

[Terry_TBR]

You REALLY need to talk with Gary Dalhke! He flys at SRA
and has several QLII of various sizes. He's a wealth of
knowledge. PM if you need his contact info.


He and I played phone tag a few times but were never able to get schedules to align in order to have a conversation. I heard the same thing from the University safety office... talk to Gary. Hopefully he will be out there on Saturday so I can pick his brain a bit before the first launch. I've been out to the launch area a few times and you're right... it is unforgiving. I have a transmitter that will be on board though so my receiver and beam antenna should get me close if there is a lot of drift.



A 30" chute for that rocket deployed at apogee may cause it to drift waaaayyyyy down range, especially on a windy day. I would go drougeless, I do it all the time with my 4" Horizon, which is about the same size as yours.


From all the advice given so far I think this is exactly what I am going to do.



rocketgroupmike is right, you can't use a J to cert level 1, it has to be a H or I motor. Then you can only fly the H & I motors.
What you can do is fly the rocket for it's test flight on a I motor to make sure your drogue etc. is right. Then take the L2 test and fly it on the J for your L2 and to test your electronics. It's a lot to do in a day, but if you're well prepared it is certainly do able.


It's too late to order motors for this weekends launch. I will have to see if anyone out there has a spare motor they would sell. If not then I just won't do any certification flights this weekend. Seems kind of weird to me though... if you can meet the L2 criteria wouldn't that mean you can meet the L1 criteria as well? Oh well... certification was just a happy side effect of this whole deal. The important part is a successful test of the electronics so I pass the course. :)

On a different note....

I installed the threaded rods into the rocket for motor retention as specified by one of the posts above. They are epoxied in pretty tight and will have over 24 hours of cure time prior to flight.

Also, as I said above, I am going to go drouge-less on this one. I appreciate all the insight on this as I was stressing about trying to find the material for a streamer. But it looks like I don't need it so no stress! I might throw a small streamer on there just to keep the payload/nose section above the sustainer stage to avoid the main getting tangled but I won't worry about having a large one to slow it down at all.

The good news is I got the avionics bay constructed and put together this evening. It fits into the payload bay perfectly and leaves lots of room for the deployment charge, wadding, shock cord, and main parachute.

T-Minus 35 hours!!

[MarkM]

Seems kind of weird to me though... if you can meet the L2 criteria wouldn't that mean you can meet the L1 criteria as well?

Why is it weird? It's all about safety. The club, the people involved, TRA/NAR want to be sure you know how to fly an H or I motor-based rocket before flying a J. A J is a sizable motor and can pose a greater risk to safety if something goes wrong. For all those involved, safety dictates that you need to demonstrate some level of competency at the lower impulse band befpre stepping up to the bigger high power motors.

[Terry_TBR]

Why is it weird? It's all about safety. The club, the people involved, TRA/NAR want to be sure you know how to fly an H or I motor-based rocket before flying a J. A J is a sizable motor and can pose a greater risk to safety if something goes wrong. For all those involved, safety dictates that you need to demonstrate some level of competency at the lower impulse band befpre stepping up to the bigger high power motors.

I understand that fully. I would think that it would be the judgment of the certification authority on-site. If someone is able to achieve the requirements for safety of a L2 launch to the approval of the certification authority then I would say it is good to go. But the rules are the rules and we play by them to ensure people do not get hurt. It was something I over looked. I did not mean to get the thread side tracked by my comment.

[MarkM]

If someone is able to achieve the requirements for safety of a L2 launch to the approval of the certification authority then I would say it is good to go.
And just how are they supposed to make that assessment? The "authority" has never seen you fly a HPR or know the quality of your build. How do they know you can accomplish this? You've never demonstrated anything to anyone that you do. That's the reason for the step-wise certification procedure.

[brianc]

Seems kind of weird to me though... if you can meet the L2 criteria wouldn't that mean you can meet the L1 criteria as well?
The first item of the L2 criteria is the flyer must be L1 certified... :rolleyes:


Be careful, fly safe and good luck this weekend!

[Terry_TBR]

It is simply a difference of opinion and insignificant in the long run really.

[Richard]

It is simply a difference of opinion and insignificant in the long run really.

A cavalier attitude about safety is a very significant issue in both the short run and the long run. In the long run, it is really not very important if you pass your course, or even if you graduate, but it is very important that you do not kill or injure someone at a HPR launch.

Clearly, you are a reasonable bright man and likely fully capable of building and flying HP rockets. If you are as bright as you appear, then you should evaluate your own lack of experience objectively and note that although almost everyone will have an opinion not all opinions are equal. Fore myself, I am very glad that you came to this forum to ask for help as this community possess both a vast wealth of knowledge and an honest and generous desire to share that knowledge with others.

I hope you have a successful and safe flight!

[bobkrech]

It is simply a difference of opinion and insignificant in the long run really.
Terry

No it isn't simply a difference of opinion, and certification procedures are significant, and always have been. Hobby rocketry self regulates, and has had an unrivaled safety record for 50 years, and we aim to keep it that way.

NAR and TRA have maintained certification policies since the start of High Power Rocketry. This mentored apprenticeship system has worked well
and is the reason why the hobby has been safe, why we can obtain launch insurance at minimal cost, why we can obtain launch sites, and why we can legally launch with minimal restrictions.

High power rockets travel at 100s of mph, and have sufficient kinetic energy to kill someone if they are hit with a wayward rocket. Additionally significant damage to property such as a car, trailer or building can occur. It is in the hobbies best interest to insure that all high power folks are properly trained in rocket design, operations and range safety, and that novices demonstrate to experienced practioners of the art before they are allowed to proceed to the next level.

The procedures for high power certification are published at http://www.nar.org and http://www.tripoli.org

High Power Certification is a three level process similare to college degrees: BS=L1; MS=L2 and PhD=L3.

The first requirement for high power certification is that you join whatever organization you will be launching with.

The second is that you build and successfully launch a high power rocket powered by a Level 1 H or I motor.

If you want to proceed to Level 2 in order to launch rocket with J, K or L motors, you first need to pass a Written Level 2 test administered by a qualified club member, then you need to complete a successful Level 2 flight.

For Level 3 certification, it's comparable to graduate school and defending a thesis. First you get your L3 project by your L3CC or TAP via a written plan, then you build your rocket and get it approved by your mentor, and then you launch.

This system works and keeps the hobby safe.

Bob

[Richard]

Bob;

That was a more constructive response than mine own.

Thanks!
Richard

[Terry_TBR]

Thank you for the responses Richard and Bob.

First, I just want to say that I do not think that anyone should take safety lightly. I realize that from my comments it may seem like I am wanting to cut corners with the certification process. I am usually misunderstood as I forget to say or type all the things in my head so usually only half the story is told. :)

I read up a lot on how the local club here operates and in order to fly your rocket has to go through a safety inspection. My point was that the certification authority would do a very close inspection of the rocket to ensure that it was built in a way that it can be safely flown to level 2 standards. This would include materials, checking for epoxy fillets on the fins, positive motor retention methods, how the shock cords and parachutes are secured, and so on. Not only would it be a visual inspection but he/she would ask questions about the process used. If there was any doubt based on the inspection or the answers given then the rocket would not be authorized to fly. The only part of my rocket that cannot be inspected is the epoxy fillets on the inside base of the fins due to the motor mount rings hiding those areas. But if the fillets on the launch lugs and external wings are used as a reference, one would see that the craftsmanship was there to ensure that the fillets on the internal fin base are to standard.

In reality, the only way to truly tell if a rocket is safe is if the certification authority watched the entire build process. But that is hardly feasible and I would really hate for someone at the NAR or Tripoli to read that and think it is a good idea to add to the rules! :p But it is my opinion that a thorough inspection and "interview" with the builder would be sufficient to prove that the rocket is in fact safe to fly.

Please do not think that I take safety lightly and am trying to find loop holes to get around. In fact, I will have the director of the University Safety Office (a long time HPR flyer and either L2 or L3 certified) on site to oversee every aspect of the preparation, launch, and recovery of the rocket. He is also the one who purchased the motors and is handling them for me as well as the one who is building my deployment charges and checked my calculations to ensure that the right amount of powder was calculated.

My comment about it being insignificant in the long run is because I do plan to follow all the rules... so my opinion of how L1/L2 could be achieved by one flight on a L2 motor is insignificant... because I am going to follow the rules and do this by the book.

On a side note, I did call the safety director and told him I wanted to see if anyone on site had a H or I that I could buy and do my first launch with. He has a 34mm I405 or something close that he said I could use. So the airframe and electronics are going to be tested first on a L1 motor before stepping up to the L2 motor.

I am sorry if I gave the wrong impression and I do thank all of you for hounding me about it when I did. Safety is the most important factor in all of this and even though we may have a difference of opinion on how that safety can be accomplished, I will still be following the set rules to ensure that I promote the hobby in a positive light to all involved.

Finally, thank you for all the well wishes on a safe and successful flight. I will be video recording everything so I can create a video of the event to show at the design showcase in April so as soon as that is done I will be sure to post it for you all to see.

[Terry_TBR]

Fore myself, I am very glad that you came to this forum to ask for help as this community possess both a vast wealth of knowledge and an honest and generous desire to share that knowledge with others.

This is something that I did notice from the first day I found the forums. It took a week for my account to get out of the moderation queue so I could post. I wish I had been able to post this sooner. If I had all the responses above last week then I would have rush ordered a few L1 motors for this weekends launch.

But yes... within 24 hours of posting the original message I had a solution for motor retention and a clear idea of what to do about a drogue. So I can do nothing more than agree with you 100% that this community does in fact generously share their knowledge and experience to help out the new guys!

[sailmike]

I hope this isn't too far off topic, but what is the electronic payload you are planning? Maybe I could do something similar for my electrical engineering degree.

Thanks,
Mike

[Terry_TBR]

I hope this isn't too far off topic, but what is the electronic payload you are planning? Maybe I could do something similar for my electrical engineering degree.

Thanks,
Mike

Hi Mike,

What I did is really quite simple but is meant to be a stepping stone for a much more involved package. For my senior design project I made an altimeter / flight data recorder that can trigger two deployment charges. It runs on the PIC18F4520 and uses the MAX232 for serial output and the 24AA128 for data storage (I2C 128KB memory chip). It uses an LED to blink the maximum altitude after the flight much like other altimeters do with sound buzzers.

The project was a lot of fun to do especially since I got to build a rocket to fly it on! :D It was pretty simple though. The next version of this project which I will be doing outside of the school will host a lot more sensors, more memory, telemetry, GPS, and all that. I basically want a one system that will do all the things I want instead of having to piece together 3 or 4 systems and pay $500+ for it all.

If you do decide to do something like this for your project let me know and I will send you some of my lessons learned.

[sailmike]

I was thinking of doing exactly that, except I would use an LCD instead of a LED. It's a pain to read the altitude or other info from the blinking LED. Let me know how yours goes.

Mike

[Terry_TBR]

I was planning on using an LCD too but then decided that the added weight wouldn't be worth it. My second generation card is going to have a "ground station" that you plug into the on board system when it gets back and that will have the LCD to read everything out on.

[Terry_TBR]

I am happy to report that the launch went very well. At first I didn't think I was going to be able to fly because of the wind. But as the day progressed it started to calm down and we got within safe limits to fly. I flew on a CTI I205. The PerfectFlite altimeter registered 1600' as the max altitude. I launched it at a slight angle into the wind and as it went up it tilted even further into the wind... hence why it only hit 1600' instead of the 3000' I was projecting. Total time in flight was 33 seconds and according to my hand held GPS it landed 0.31 miles from the launch pad. It took 2 hours to find... our launch area is overgrown and unforgiving!

Lesson Learned... USE A BEEPER!!!

The motor retention method PantherJon posted worked beautifully! The motor was retained and the rocket was not damaged... even the paint job was exactly as it was when I put it on the pad. But it doesn't have that new rocket smell anymore... now it smells like a black powder charge went off inside of it! :D

As soon as I show my certification authority the rocket I will be signed off level 1. Everyone left before I actually found the rocket. Hahaha.

I will do a much more in depth write up and post pictures of the launch and result here soon.

[DAllen]

The motor retention method PantherJon posted worked beautifully! The motor was retained and the rocket was not damaged... even the paint job was exactly as it was when I put it on the pad. But it doesn't have that new rocket smell anymore... now it smells like a black powder charge went off inside of it! :D


Good job! I think the BP smell after I got my L1 was one of the sweetest smells ever. Welcome to high power...now open your wallet.

:D

-Dave

[Terry_TBR]

Good job! I think the BP smell after I got my L1 was one of the sweetest smells ever. Welcome to high power...now open your wallet. :D
-Dave

HAHA! While I was tromping around in the over grown fields and scrub looking for the rocket I wasn't thinking about how bad I was going to feel if I couldn't find it. I was thinking about what my wife was going to say when I told her I had to buy another one! :D

Attached are some pictures of the launch. Some were taken with a Canon 5D 28-135mm lens and others (-M in the file name) with a Canon 20D 100-400mm L lens.

It was a pretty awesome launch. It feels good... but it feels even better to think that I have three J415W's sitting in storage waiting for the next launch! :D

[jj94]

HAHA! While I was tromping around in the over grown fields and scrub looking for the rocket I wasn't thinking about how bad I was going to feel if I couldn't find it. I was thinking about what my wife was going to say when I told her I had to buy another one! :D

Attached are some pictures of the launch. Some were taken with a Canon 5D 28-135mm lens and others (-M in the file name) with a Canon 20D 100-400mm L lens.

It was a pretty awesome launch. It feels good... but it feels even better to think that I have three J415W's sitting in storage waiting for the next launch! :D

Nice launch. But that seems way too much at an angle. I'd launch maybe 2/3 of that angle in 10 mph winds.

And how did you manage to get three J motors? I thought it was illegal to obtain motors any higher than what your certification permits you to buy, own, and fly. That is, unless you're going for the next cert. level, but that still only gets you one motor in the next cert. range. Not three motors.

[Terry_TBR]

Nice launch. But that seems way too much at an angle. I'd launch maybe 2/3 of that angle in 10 mph winds.

And how did you manage to get three J motors? I thought it was illegal to obtain motors any higher than what your certification permits you to buy, own, and fly. That is, unless you're going for the next cert. level, but that still only gets you one motor in the next cert. range. Not three motors.

I think it was too much angle as well based on the results. We had 20mph winds earlier that morning. I am not sure what they were at exactly when I launched but based on the previous high power flights I didn't want to take a chance. The direction it is leaning has a mile or more of overgrown fields. The opposite direction (the way the wind was blowing) is a huge canal about 500 meters or so away. So it was a choice on either walking or swimming.

Long story on the motors which is talked about a little in the whole thread. I am planning on certifying with one of them. If I had to launch with them without the cert then I wouldn't be the one launching them. They are for testing my senior design project - I need the higher power and high altitude to verify the requirements.

[daveyfire]

It looks like you have built the rocket stock, with the Quantum Tube airframe, 0.062" G10 fins, and the standard phenolic coupler. I would caution you at this point against flying the vehicle on a J415W. On that motor, the rocket will reach 0.99 Mach, which is well into the transonic region. If the vehicle is flying at anything greater than a few degrees of angle of attack, the unreinforced phenolic coupler is likely to fail.

In addition, the fins on the Quantum Leap extend 5" from the airframe tube. With 0.062" thick fiberglass, they are very likely to flutter at medium to high velocities; you may end up losing fins on the way up as the vehicle goes transonic.

I would recommend working up to the J415W in power and carefully watching the flight for indications of fin flutter. If you want to go high, you could also try staging the vehicle on two smaller motors with a staging delay to keep the maximum velocity down. You could also try flying on a lower thrust motor with the same total impulse (e.g., J135W) to achieve the same altitude at a lower velocity.

Congrats on the cert flight. Welcome to high power!

[Richard]

Terry;

Let me add my congratulation on your memorable flight and your lvl 1 cert.

Well done!
Richard

[Terry_TBR]

The fin base is covered in fiberglass cloth and glassed on with a great deal of Proline Epoxy. Is that enought to protect them and reduce flutter under these conditions?

[n5wd]

... Seems kind of weird to me though... if you can meet the L2 criteria wouldn't that mean you can meet the L1 criteria as well? Oh well... certification was just a happy side effect of this whole deal.

Just like a University doesn't award you a Master's and a Bachelor's at the same time, you do your L1 first, and then when that's successful, you can take the test for L2, and if you pass, then do your certification flight. Baby steps.

Anywho - congratulations on your successful L1 flight! Great pix! And, good luck on the final project - is your prof amenable to giving partial credit in case something on the flight doesn't work quite right?

[Pantherjon]

I am happy to report that the launch went very well. At first I didn't think I was going to be able to fly because of the wind. But as the day progressed it started to calm down and we got within safe limits to fly. I flew on a CTI I205. The PerfectFlite altimeter registered 1600' as the max altitude. I launched it at a slight angle into the wind and as it went up it tilted even further into the wind... hence why it only hit 1600' instead of the 3000' I was projecting. Total time in flight was 33 seconds and according to my hand held GPS it landed 0.31 miles from the launch pad. It took 2 hours to find... our launch area is overgrown and unforgiving!

Lesson Learned... USE A BEEPER!!!

The motor retention method PantherJon posted worked beautifully! The motor was retained and the rocket was not damaged... even the paint job was exactly as it was when I put it on the pad. But it doesn't have that new rocket smell anymore... now it smells like a black powder charge went off inside of it! :D

As soon as I show my certification authority the rocket I will be signed off level 1. Everyone left before I actually found the rocket. Hahaha.

I will do a much more in depth write up and post pictures of the launch and result here soon.

Congrats on a successful flight!:D


You will find that RockSim is pretty generous in it's altitude predictions..Also, a good recommendation is to tilt the rod WITH the wind..The rocket will naturally try to go into the wind(weather cock) and you will end up with a truer straight up flight..And that equals to a bit higher altitude..It is counter intuitive, because it just seems more appropriate to tilt into the wind, which will make it weather cock more and get a lower altitude..

[shoitsma_86]

Congrats on a successful flight!:D


You will find that RockSim is pretty generous in it's altitude predictions..Also, a good recommendation is to tilt the rod WITH the wind..The rocket will naturally try to go into the wind(weather cock) and you will end up with a truer straight up flight..And that equals to a bit higher altitude..It is counter intuitive, because it just seems more appropriate to tilt into the wind, which will make it weather cock more and get a lower altitude..



Please correct me if I'm wrong, but I believe that this is only true if your rocket is overstable (i.e. top heavy), because the wind will push on the aft end of the rocket, so the noise points INTO the wind; whereas if your rocket is understable, the wind pushes on the forward end of the rocket, so the nose points WITH the wind.

-Steve

[Terry_TBR]

That is a very interesting point. The main reason I pointed it into the wind is for the drift on recovery. I expected it to drift in the higher winds and didn't want it to land west of the launch pad (much closer to the swamp / canal). So I pointed it more into the wind hoping that it would land east of the pad.

But... it landed WAY east of the pad! I've been examining the data and have pretty much determined this is what happened... It left the pad at a slight angle and very shortly after "weather cocked" into the wind making the flight much more horizontal than vertical. It topped out at 1600' and actually maintained that altitude for a few seconds. The motor was actually an 11 second delay as I expected more vertical flight and was hoping the delay would allow the rocket to coast up to a higher apogee before separating the rocket (no drogue installed). Instead, the rocket maintained its ballistic nature and began its descent nose first making me quite nervous of lawn darting. As it passed through 500' the electronics package deployed the main parachute and at almost the same time the motor delay was reached and the motor separated the sustainer and payload sections. I actually think the main came out slightly before the motor ejection charge popped. Since the rocket remained ballistic and had the more horizontal flight it had very little drift and landed close to where the chutes were deployed.

Everything worked as it should but if I were to repeat this exact flight in the same conditions I would adjust the motor delay to 5 seconds causing the ballistic nature to be broken up at apogee rather than at about the same time the main came out. This would have made it land closer to the pad and also not made me start sweating thinking it was about to lawn dart!

Thanks to everyone for the congrats on the level 1 flight. I've always been into rocketry to some degree but I am really hooked now. It wasn't more than two or three hours after getting home from the launch that I was on Wildman's site looking at some of the kits he has available and thinking what will be my next project!

[Rocketjunkie]

That is a very interesting point. The main reason I pointed it into the wind is for the drift on recovery. I expected it to drift in the higher winds and didn't want it to land west of the launch pad (much closer to the swamp / canal). So I pointed it more into the wind hoping that it would land east of the pad.I have found from many dual deploy flights, all drogueless, that the best angle to launch in wind is straight up. It will weathercock enough on most motors to return fairly close to the launch area. Long burn motors usually result in an up wind landing and very high thrust motors down wind. An exception is tube finned rockets. They don't weathercock.

[DAllen]

Please correct me if I'm wrong, but I believe that this is only true if your rocket is overstable (i.e. top heavy), because the wind will push on the aft end of the rocket, so the noise points INTO the wind; whereas if your rocket is understable, the wind pushes on the forward end of the rocket, so the nose points WITH the wind.

-Steve

Understable rockets = skywriting + very unhappy RSO's

Point that rocket straight up. Adjust slightly to ensure that it does not go over everybody's head and you are good to go.

-Dave

[Delta-IV]

Congrats Terry, to do what you did so quickly is awesome.

By your experience in getting your Level 1 flight off. I hope you have gained the knowledge that even hobby rocketry isn't easy, it really isn't.

As in my profession, the real rockets are very not easy, we may at times make it look so, but if it was that easy then Iran and North Korea would be raining down missiles on us this very day.

If your project is a Senior one, this is still March I'd think a knowing professor would give you the time to do it the proper way, and that is 1 step at a time.

I have been a Level 1 now for almost a year and I am not yet ready for Level 2, I am working on it though 1 step at a time.

Good Luck.

[Terry_TBR]

The senior design showcase is on April 3rd and project completion demonstrations are this coming week. We are at the end of the project which all started last August. But all last semester and the beginning of this semester was all project proposals, design reviews, and all that. We didn't start building until February. Then there was the fact that parts have to be ordered through the University office which means they were ordered late. Then there was back ordered parts. You know... all the things that happen with real projects! These are all things that we have to deal with and get around in order to have a successful project and a passing grade. So, in the end, I ended up having a week to build the rocket. But I did my research, talked to some experienced builders, and made sure I did everything right. Even still, I had overlooked a few things like motor retention but was able to take care of that a few days before launch. The professor had no insight into the rocket flying part... only the electronics design part. The rocket flight to test the system was on me. If it wasn't done right then I would not have been able to fly nor would I have flown if I thought there had been a problem. I didn't just throw a rocket together, install a motor, and push the button. :p

I wouldn't say high power rocketry is easy or hard. I would say it is complex. Each individual thing that you need to do is quite simple. But when you put all those individual things together in order to build and fly a high power rocket, you are dealing with a very complex system. Its like playing basketball. It is easy to make a shot when you're the only one on the court. Now add a whole team of 7' players against you and suddenly it is very tough to make a shot!

Based on my experience, my advice to someone wanting to get into high power rocketry is to talk to experienced builders and go to a launch to see if for yourself. Ask a ton of questions and see each and every step from preparation to recovery. I should have done more of this.

[judo]

You REALLY need to talk with Gary Dalhke! He flys at SRA
and has several QLII of various sizes. He's a wealth of
knowledge. PM if you need his contact info.

Gary's QLII J-335 to H-128.

http://www.nefar.net/gallery/2009-02/Quantum-Leap-2-Stage-Gary-Dalkhe-J335-H128.wmv

[Terry_TBR]

Here is a short video on YouTube of my Level 1 launch...

EDIT: Guess you cannot embed the video. Here is the link: http://www.youtube.com/watch?v=YZB9NwRJjQs

[jj94]

Here is a short video on YouTube of my Level 1 launch...

EDIT: Guess you cannot embed the video. Here is the link: http://www.youtube.com/watch?v=YZB9NwRJjQs

Wow that was fast. Nice flight.

Oh, and I've been trying to find out how to embed videos into posts for a while too. I just can't seem to figure out how.

[daveyfire]

The fin base is covered in fiberglass cloth and glassed on with a great deal of Proline Epoxy. Is that enought to protect them and reduce flutter under these conditions?

Possibly. The primary concern with flutter is from breakage by fatiguing the material. To reduce flutter, the entire fin should be made thicker, since stiffness goes up with the cube of the thickness. 0.062" thick G10 is *very* thin as HPR fin materials go, especially for a J motor. (Try "plucking" the fin from its tip and listen to it resonate.) Additionally, a heterogeneous fin material will help kill flutter, as the varying materials will have different resonant frequencies; each material will damp out vibrations in the other, to some extent. An asymmetrical fin thickness also helps -- thicker at the root, thinner at the tip -- as it varies the resonant frequency as a function of span.

To be absolutely positively sure the fin won't flutter, the elastic axis of the fin must be behind the spanwise center of gravity -- basically, imagine drawing a line connecting the center of gravity of each infinitesimally small slice of fin looking from the root towards the tip; the line along which the fin bends should be behind this line of centers-of-gravity. Just like in a stable rocket, in this case the restoring force of any fin motion tends towards zero deflection, and the fin cannot flutter. For an elastic axis on the center of gravity line, the fin is neutrally stable; for an elastic axis ahead of the center of gravity line, the fin is harmonically unstable and can develop a flutter condition.

Probably more information than you wanted :) The attachment is two photos of a PML Bulldog about to flutter its fins off. The first photo is the flutter beginning to develop; note the deflected fins and the development of a wave pattern in the exhaust plume. The situation gets worse in the second (out of focus) picture, with major deflection at the fin tips and a significant pressure variation in the rocket's wake. The spread, "pulsated" smoke trail is a key sign of developing flutter during a flight. That, and you could hear the fins buzzing on the way up before the rocket tore itself apart!

[JimJarvis50]

The fin base is covered in fiberglass cloth and glassed on with a great deal of Proline Epoxy. Is that enought to protect them and reduce flutter under these conditions?

I had a QLII that I built stock with fiberglass over the fillet area. True to its reputation, the fins fluttered at about Mach 0.9. It's pretty much guaranteed to happen. Bad news ... the rocket was a total loss. Good news ... I learned to build stronger rockets.

Jim

[bobkrech]

Just to reinforce what has been said in the previous posts. The stock PML Quantum Leap is not designed for use with J motors because the airframe is Quantum tube which is not intended for transonic flights and the fins are only 0.063" inches thick and they will flutter in transonic flight.

The following is from the PML FAQ http://publicmissiles.com/images/PMLCompleteFAQ.pdf

Quantum Tube

These great airframe tubes are made in the USA from a special blended polymer that is extremely durable and easy to use. Quantum Tube can be squeezed, dropped, or even thrown and will not suffer any damage as can sometimes occur to cardboard or phenolic tube. You will find this new material easy to work with and very forgiving, even during those “less than perfect” flights. All components that fit PML phenolic tubing fit QT also.
• The Quantum Tube (QT) has been tested and found compatible with the following paints: lacquer, enamel, epoxy and urethane, as well as many different primers. As with any paint, apply several light coats allowing each to flash before re-coating.
• Most brands of epoxy adhesive bond well with no adverse affect to the tubing. The bonding area must be sanded prior to applying epoxy. Follow the suggestions in “Do’s and Don’ts” below.
• QT does not fiberglass well for body tube strengthening. We DO NOT recommend QT for 0.85+ Mach kit strengthening as mentioned elsewhere in this FAQ.

Some customers have thought that QT is a replacement for ‘glassed phenolic. This is not the case! Quantum Tubing is not intended for super-high-stress applications. It is intended as a replacement for standard phenolic for sport rockets. QT makes it easier and faster for flyers to achieve a nice finish, and to eliminate some of the problems of plain phenolic in high-impact situations like landing on rocks, cold-weather flying, etc.

Fiberglassed phenolic is the best product for high stress flights. Also, follow the PMLCompleteFAQ.doc recommendations in the Kit Strengthening section of this FAQ if the flight will be near or exceed 0.85 Mach.

Kit Strengthening

As mentioned on the first page of the Motor Recommendations Chart on the Specs Page of the website, chart cells are highlighted for kit/motor combinations that require strengthening. We recommend the following changes for strengthening:
• Fully-glassed airframe, which requires phenolic as a starting point, not QT. You must special-order your kit with phenolic as all kits 3.9” and under (except Nimbus) come standard with QT.
• Thicker fins (0.063" should go to 0.093", 0.093" should go to 0.125")
• Fin-to-airframe joints should be glassed
• 30-minute epoxy should be used throughout the build.
• Some customers have asked if they can “double-up” or “sandwich” two pieces of G10 to create a super-thick fin for very high impulse flights. We don’t recommend it; at high speed airflow can split them.

You should believe the manufacturer. The issue with the stock QT airframe is a potential for column buckling due to insufficient airframe stiffness and the problem with the stock 0.063" fins is insufficient thickness to resist flutter above Mach 0.85.

There's not much you can do about the airframe since PML does not recommend fiberglassing QT, however the fins can be stiffen by adding 3 layers of 0.006" unidirectional carbon cloth to the fins. http://www.sollercomposites.com Unidirectional carbon is far stiffer, stronger and lighter than FG and is easier to apply that woven fabric. (I would recommend a 0-120-240 layup to maximize the overall stiffness.)

Your rocket may fail due to the QT airframe, but the stock fins will definitely fail with a J motor unless you stiffen them to at least 0.093" thickness, preferably with CF.

Bob

[Terry_TBR]

Thank you for the in-depth responses. This is really starting to tick me off. I looked at the PML motor recommendations for all the kits and there are plenty of J motors on that list and only a few of them recommend kit strengthening. It seems there is a disparity between their FAQ and their recommended motor lists. From the looks of it there is no good way to strengthen it either. Needless to say, I seriously doubt I will be building any rockets from QT in the future if it is that bad for higher power flights. In hindsight, I should have bought a different kit as this one will not do what I wanted it to do. Live and learn...

Now to find someone local who wants to buy a few J415's... :(

[MarkM]

You could have gotten the QL with phenolic tubing (no extra cost) and glassed it and then glassed the fins to the airframe. And I think you can upgrade the fins to a thicker G10, just pay for it. No problem for this to then handle the J415.

Quantum tubing is great for the beginner in terms of finishing, but a very inadequate tube for flying big motors. Personally, I think PML should only market their smaller kits and the ones really meant for smaller motors and beginning HPR fliers with the Quantum as standard and the option for phenolic. The larger kits and those most individuals would probably use for larger motors (like L2 certs) should be the opposite ... come standard with phenolic with the option for Quantum due to Quantum's limitations.

PML undoubtedly makes some nice kits, but think that marketing most of their kits with Quantum as standard is a poor idea.

LOC/Precision make some great kits whose stock cardboard tubes will hold up to a J415 without reinforcment.

[Terry_TBR]

I find the PML webstore a bit tough to use myself. I do not find their information to be laid out well. But then I could say the same for most of the rocket vendors I've gone to as well. But I understand the small businesses not wanting to shell out $1k+ for a fancy site.

I really should have paid closer attention to what motors could and couldn't be used. I know there is no one to blame but my own inattentiveness. Personally... I am all about flying higher and faster. I just picked a kit in a hurry due to the time constraints I was under and it won't live up to what I wanted. It is still a nice rocket, was easy to build, looks good, and flies great. That and she will always be my first... :D I just have to fly her a little lower and slower then I would like.

No worries... next one I order will be glassed body tubes, thicker fins, and known to support the bigger motors. And I will make darn sure of that before I pull the credit card out. ;)

[new2hpr]

Go through some more simulations, focusing on the lower thrust, longer burn motors. You should be able to find a combination to put it up there a ways and stay away from mach. Take a look at the J90 and J135, depending on the weight.

Ken

[Terry_TBR]

It's been a busy week getting everything ready for the senior design showcase but everything went off without a hitch. The showcase was yesterday and my electronics payload project won best in show for the electrical and computer engineering group. I had a make shift pressure chamber made out of three glass jars, some tubing, and a vacuum pump that I used to simulate a rocket flight. I customized the software on the uC to turn a LED on and off to show when the drogue charge was fired, the main charge was fired, when launch was detected, and all that. It was a big hit.

I wrote up a little more about the project and the showcase here: http://www.tbrocketry.com/2009/04/senior-design-showcase-result/

I also attached some pictures of the event.

Thanks again to everyone who helped put my head on straight regarding the motor retention and motor selection.

[sailmike]

Congratulations on the award! Now you just need to test it on a real rocket. I like your goals for the project, to get more kids interested in science and engineering.

Mike

[Terry_TBR]

Congratulations on the award! Now you just need to test it on a real rocket. I like your goals for the project, to get more kids interested in science and engineering.

Mike

Define real rocket. I tested it on the HPR I built from the QL II kit.

[sailmike]

Ah, I must have missed that post.

Mike