Level 1 Certification?

[timothyterpsalot]

I don't think there was ever a question of whether I was planning on using a recovery system or not. I was asking whether I should use electronics or rely on motor ejection.
I might be able to make it to other launches, we will see.
As for the kit, I am trying to keep it simple and cheap. I've heard bad things about phenolic but it's cheap and simple. I don't think this rocket will see too much flight time as I don't know of anywhere in the Kansas City area to launch unless I want to drive four hours to Argonia. For that reason I think phenolic wouldn't be a terrible choice for this rocket.

 

[hardinlw]

Well if Bob's found a field in New England with only one rock in it, I want to know where it is.

I certified L2 on a PML Black Brandt X which is phenolic and I've replaced two sections of airframe because of landing on rocks, glassing them as I replaced them. My venerable PML D Region Tomahawk on which I got my L1 may have made its last flight because the two sections managed to slam together when the parachute deployed and pretty much shattered.

If you are careful about sticking pistons, the PML quantum tube works fine. I have several L1 rockets made of it and a scratch built upscale of the Estes Stiletto (4" dia) that I fly on a J420 with no problems. Then there are the all-glass kits. The Wildman Jr would work for L1, but at 2" dia, it may go higher than you want.

 

[Diosces]

I concur with all the KISSER"S.
Do a simple paper and plywood fin rocket with a simple Aerotech RMS.
LOC EZI-65 or Binder Thug are really solid Level 1 capable rockets that can be flown aggressively on future flights

Recovery problems represent over 75% of rocket failures. I suggest a sturdy, reliable recovery be where you concentrate any 'extra' efforts.
Consider motor ejection with parachute recovery. ALthough rare, premature motor ejection can bite ya. Longer delay with a zipper resistance design could be the 'bells & whistles'.

Most people at a high power launch will be willing to witness/assist with your first motor assembly.

Have fun, ask questions, and watch what goes on at the launch. Don't rush and everything will go well.

 

[MarkM]

Then there are the all-glass kits. The Wildman Jr would work for L1, but at 2" dia, it may go higher than you want.

If you want to go the all glass route, Performance Rocketry has a few 3" kits that would be perfect for an L1 cert. Wildman Rocketry currently has a 15% off sale on these kits. The only issue is they don't come with any recovery gear, but Wildman has the materials you'd need...he'll set you up, right.

 

[mikeyd]

Tim, thanks for the reply, and the updates of where you are at, both location, and experience. This is a good place to start to get more of the experience side of things. I too had to certify on a shoe-string budget. I was able to do Level 1 for less than $20, most of this was the "kit" costs. I did this with one of the Ralphco 36" tall crayon banks, cut the centering rings form left-over 3/8" thick plywood, had to aquire some 29mm motor tube, but If I were to build it now, would go with 38mm, which means, I could use 1.5" mailing tube. (did this on my level 2 crayon) My parachute was made from a 54" golf umbrella, bought some u-bolts from the hardware store, and 3/8" bungie cord for the shock cord. I was able to borrow the 29mm case, and won a certification reload from Aerotech, and Off I went. I was even accused of hitch-hiking to the launch. This was at LDRS99 before I joined Kloudbusters, or Tripoli. I did over build this, but had a succesfull flight. THe only reason I went into such detail, was to explain that you do not have to use a store bought kit, if you feel you can build your own. The crayon banks can be found at most Toy's R Us for about $7, and they have a nice heavy card board tube. You can find mine here https://members.cox.net/shortckt4/main.htm
Hope all of this helps
Mike Dickinson

 

[troj]

I don't think this rocket will see too much flight time as I don't know of anywhere in the Kansas City area to launch unless I want to drive four hours to Argonia.

It's not a significant time difference, but our launch site (Pickrell, NE; near Beatrice) is a little bit closer to you than Argonia.

-Kevin

 

[timothyterpsalot]

Actually, your field is about 7 minutes closer! :roll:
I never knew about the launches up there, I will have to keep that in mind. Everyone here has been such a great help! I'm shocked at how welcoming everyone is.

 

[Marsman]

Since everyone is talking about phenolic and cardboard, I'm in much the same situation as the original poster. I'm looking to get my L1 this summer, and am probably going to scratch build the rocket.

I've flown a bunch of G motor reload flights with altimeters, timers, airstarts, staging, etc. I just want to kick it up a notch to the High Power world. Most of my rockets so far have been built with the spiral-glassine tubing from Red Arrow. The stuff is fine for what I've done, including a 29mm machbusting flight. (I didn't get that one back, but I think it survived. The boost was good ).

My question is how does the 'Phlexible Phenolic' compare to the spiral glassine tubing? It's heavier, but supposedly stronger and flexible so it doesn't shatter like phenolic.

Secondly, will the spiral-glassine tubing stand up to full I motor flights in the transonic range? My concern is that if the angle of attack gets too high, the rocket will bend in half during boost. But then again, I couldn't bend my 4" spiral-glassine rocket in half if I wanted too...

 

[troj]

My question is how does the 'Phlexible Phenolic' compare to the spiral glassine tubing? It's heavier, but supposedly stronger and flexible so it doesn't shatter like phenolic.

Flexible phenolic is indeed less prone to shattering. It's not heavier, rather it's made a bit differently than conventional phenolic, which resolves some of the brittleness.

It's not as flexible as conventional cardboard tubing, however.

Secondly, will the spiral-glassine tubing stand up to full I motor flights in the transonic range? My concern is that if the angle of attack gets too high, the rocket will bend in half during boost. But then again, I couldn't bend my 4" spiral-glassine rocket in half if I wanted too...

Spending time up close to Mach is where you run into problems. If that's your goal, I'd definitely suggest you consider fiberglassing it.

But if you're not going to try to bust Mach, or flirt with it, then either cardboard or phenolic will work.

-Kevin

 

[Marsman]

Like you mention, I've head before that you need fiberglass or carbon fiber for transonic or Mach flights, but I'd like to understand the forces a little bit better.

As I understand it, the primary problem in a transonic flight is the shockwave moving back down the rocket as it accelerates. Common effects of this are ripping the fins off of the rocket body (often via fin flutter), especially if the shockwave is disturbed by protuberances on the airframe such as launch lugs or rail buttons.

The solution seems to be to build strong or thick fins to deal with the first problem. However, this does not address the need for a fiberglass or carbon airframe. What are the effects of the transonic region going to do to the body tube? Crush it under the pressure/g forces? This seems unlikely. Bend the tube if the rocket weathercocks a bit or flies at a higher than vertical angle of attack?

What is it that would cause the airframe to fail, and why does fiberglass and carbon fiber avert this? Why wouldn't cardboard or phenolic work?

Should this be split into a separate thread?

 

[madmax]

You don't need a fiberglass airframe to go supersonic! Cardboard and phenolic do just fine. I personally fly close to or through Mach on many of my flights. Most of these on nearly stock Binder Design kits. Just two weeks ago I put up my Binder Sentinel #2 on a J800T. 9# 12oz. pad weight. 5676 feet altitude. Rocksim simulations put it right around 900 ft/s. Right there in the transonic region. Last season I flew Sentinel #1 on a K1100T then a L1000 Research motor the next day. Held together just fine during boost but somehow deployed the main at ~10,000 feet. We watched it float for 10mins before touching down. Usually the only modifications I make to the stock build is doing a zipperless design and fiberglass the inside of the coupler. I got bit in the past by a coupler folding on a high speed flight. However I did not do this with Sentinel #2 and it seems to be just fine.

I will agree though that fiberglassing standard phenolic is a good idea since it is so brittle. If you have the recovery room a large chute would probably help to prevent cracking the phenolic if you do decide to go that way.

I recommend any of Binder Design kits for both L1 and L2 flights. Built stock they will be just fine on just about any motor. Also LOC has some really nice kits as well.

 

[cjl]

Honestly, I would be perfectly comfortable using unglassed phenolic, or even quantum tubing (in smaller diameters - I wouldn't try for supersonic flight with 4" quantum) for a supersonic flight (up to perhaps mach 1.4 or so). The main failure point from what I've seen tends to be fin flutter, not actual tubing failure. Now, if you want to push it a bit farther, up into the mach 1.5+ range, then the forces start getting high enough that I would probably glass it to feel a bit more comfortable, but in the lower mach 1 speed range, I wouldn't worry about the tube unless it was something like a rather thinwalled plain paper tube.

 

[MarkII]

I realize that this goes way, way, way beyond any Level 1 considerations, and is thus well off-topic, but when (as in what multiple of Mach or duration of powered flight) does heating due to aerodynamic friction become an issue?

MarkII

 

[cjl]

From what I've seen (I've never flown anything where it became significant), I'd say you don't have to start worrying until you spend significant time above mach 2 or so. A quick warp 9 flight to mach 2 probably won't have the time at that speed for it to become significant, but if you fly a minimum diameter on an M650 that spends 4 or 5 seconds at that kind of speed, it will probably be significant. Of course, as I said, I don't have any personal experience with that level of extreme flight.

 

[MarkII]

Thanks - that's exactly what I was looking for. I had heard of it happening on some extremely high or record-setting minimum-diameter flights, and I was just curious about what combination of factors would lead to, say, cooking the paint off the nc or softening the epoxy on the fins. Like I said, this has nothing at all to do with Level 1 flights, but I had wondered about for awhile, and the talk of going beyond mach 1.5 reminded me of it.

MarkII

 

[cjl]

Well, I have flown to about mach 1.75 on an I600 minimum diameter shot with no visible effects from heat. The threshold is definitely above that.

 

[madmax]

The threshold is not just based on speed but your duration at said speed. A small part of it is speed since you can fly a minimum diameter on a K1100T and a small amount of paint will be burned off. Mainly tips of fins and nose cones. If built light enough that flight should break Mach 2. However if you stay supersonic for a sustained period of time you will end up burning off much more paint. Having witnessed numerous flights of this type I can say I have never seen softening of the epoxy due to heating. This may be more a product of the builder doing a good job than anything else since I am sure it can and does happen. Look up pictures of Robert DeHates crazy MD two stage from Balls 06. The fin layups got peeled back from the leading edge. That flight was supposed to hit Mach 3.

On the upside you only encounter these type of problems when the bird holds together through the boost!

 

[timothyterpsalot]

Okay, I think I'm going to purchase a 38/120 but I'm not confused as to what S, M, L means for the delay... do they stand for like 6, 10, and x number of seconds?
I want to put it in the escape velocity rocket from giant leap (purchased it today). Rocksim says on a windless day it can put it up to 500 feet (whoo hoo....) now the only problem is the delay on the motor. It needs to be 6 seconds..would that be an S? Thanks

 

[C.O.B.H.C.]

The threshold is not just based on speed but your duration at said speed. A small part of it is speed since you can fly a minimum diameter on a K1100T and a small amount of paint will be burned off. Mainly tips of fins and nose cones. If built light enough that flight should break Mach 2. However if you stay supersonic for a sustained period of time you will end up burning off much more paint. Having witnessed numerous flights of this type I can say I have never seen softening of the epoxy due to heating. This may be more a product of the builder doing a good job than anything else since I am sure it can and does happen. Look up pictures of Robert DeHates crazy MD two stage from Balls 06. The fin layups got peeled back from the leading edge. That flight was supposed to hit Mach 3.

On the upside you only encounter these type of problems when the bird holds together through the boost!

Here is a link to info on Robert Dehates rocket from BALLS 2006. https://www.geocities.com/rdh82000/NmotorRocket/index.htm

 

[cjl]

Okay, I think I'm going to purchase a 38/120 but I'm not confused as to what S, M, L means for the delay... do they stand for like 6, 10, and x number of seconds?
I want to put it in the escape velocity rocket from giant leap (purchased it today). Rocksim says on a windless day it can put it up to 500 feet (whoo hoo....) now the only problem is the delay on the motor. It needs to be 6 seconds..would that be an S? Thanks

That would be an S delay, yes. S is 6 sec, M is 10 sec, L is 14 sec.

 

[mikeyd]

Okay, I think I'm going to purchase a 38/120 but I'm not confused as to what S, M, L means for the delay... do they stand for like 6, 10, and x number of seconds?
I want to put it in the escape velocity rocket from giant leap (purchased it today). Rocksim says on a windless day it can put it up to 500 feet (whoo hoo....) now the only problem is the delay on the motor. It needs to be 6 seconds..would that be an S? Thanks

Tim, I am a little confused here. isin'tthe Aerotech 38/120 a G only? If so, It is a good place to learn reloadable, but does not require level 1. Also the Escape Velocity kit, has a pre-molded fin can, I am not sure this can be used for a Certification rocket. Anyone know for sure?

These choices will give you some good loading, and flight experience though.
Good Luck!
Mike Dickinson

 

[timothyterpsalot]

Crap! I read the tripoli rules wrong! It can't be used. I just ordered it, maybe I still have time to cancel it...

 

[timothyterpsalot]

Also, someone suggested that I get the 38/120 to learn how reloads go together, that's why I wanted to do that.

 

[timothyterpsalot]

Well now I'm not too sure...It says premolded fincans cannot be used for LEVEL 3 certification flights but says nothing for level 1. I need to know quickly if possible so I can cancel the order I made. Thanks.

 

[hognutz63]

Also the Escape Velocity kit, has a pre-molded fin can, I am not sure this can be used for a Certification rocket. Anyone know for sure?

Mike Dickinson

Only on level 3 certs are pre-fabbed fin cans not allowed.

https://www.tripoli.org/cert/TRA_Certification_Rules_2009.pdf

You are correct Tim.

Eric

 

[timothyterpsalot]

Thanks! I got scared there for a second!

 

[mikeyd]

Sorry all, did not mean to create a scare, I was not sure myself that is why I asked as well.

Tim, Sorry to put a scare into you, just wanted to be sure. Also the 38/120 is a good motor, I use mine with the redlines, and really like it.

Good luck, and Happy Flying!
with any luck I may be at the Nebraska launch in June, maybe see you there.
Mike

 

[w9ya]

One of reasons I preferred to get my certs with the NAR is that doing so allowed me more freedom to 'think outside of the box' and do some interesting (to me) things on my cert. flights.

Even if I agree with no pre-fabbed fins on a cert 3 flight; the rules, in general, are more restrictive than what I feel is necessary.

*** Certainly I could not have had the fun I had with the designs I ended up constructing and flying for certification had I done so within the TRA's cert. process. They are not allowed.

 

[timothyterpsalot]

Okay...So now I have the dilemma of choosing where to pick up my 38/120 reloads. I have an opportunity in Argonia and in Nebraska. I've never been to any launches up there. Is the launch on June 19-21 going to be a significant one? I looked on the site but didn't see a whole lot of info.

 

[troj]

Is the launch on June 19-21 going to be a significant one? I looked on the site but didn't see a whole lot of info.

"Significant" is relative.

To us, it's a good-sized launch. But it's nowhere near the size of AirFest. With the KLOUDBusters contingent that's coming up, we'll probably have 30 to 40 fliers. I know we'll have two vendors on site, and both carry AeroTech.

With your plans to get L1 at AirFest, I'd encourage you to come up this month, and talk with folks and use it as an opportunity to ask questions, learn more about HPR, etc. That way, when you get to AirFest, you can focus more on flying.

If you have the kit and bring it along, we may be able to make some recommendations on it, as well.

-Kevin