Back After 50+ Years

NateLowrie said:

I did not see an answer to this, but thought I would clarify. That questions packet and the test are only for Level 2 certification. For level 1, it's basically show up with your rocket, fly it and safely recover, and the certifying person inspects the rocket to make sure there is no damage that would hinder you from immediately flying again.

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The NAR test is a bit easier. Nothing in there regarding research motors. :wink:

Oh yes, I did read that also. Sorry I wasn't so clear when I said that. It just means I may never progress beyond L1, unless I get a better memory. But I did do a couple of questions without any study, and got them all correct. Hopefully I can do the written test successfully. I've never had a very good memory. Kept me back in school. My Dad (an old US Marine, and generally grouchy), joked that I was fortunate I was gifted with "One" brain cell. :smile:

Anyway, Rex and Mike L., thanks for the help. I went to Thrustcurve in one browser page, and to Apogee in another, and found hopefully an adequate motor, an E6-6 Aerotech. This motor I believe only puts out 40 newtons, but after recalculating things, that is only 8 newtons lower than the ideal, and about 30 newtons more than the recommended motors are, which probably couldn't get the airframe off the launch rail. At the same time I ordered the retaining rings to replace the motor hook. I also ordered some Kevlar cord to replace the wimpy elastic shock cord. So, in about a week, I should be able to do a small upgrade, and be ready for next month. Caley Ann

Some of the cert questions are just stuff you know from doing rocketry. But, unfortunately, you are going to have to memorize things like minimum safe distances from the pads, Ns ranges for impulse classes, etc. No way around it for Level 2.

I'd be cautious with the E6-6. That's a long burn low thrust motor... around 6s burn time I think. In a 10oz rocket something with higher average thrust would be ideal.

Yeah, I can see that now that I realize I was looking at total thrust, instead of average thrust. It's still stronger than the little ESTES motors I bought. If they don't work, I can always give them to someone that can use them.

Caley said:

Yeah, I can see that now that I realize I was looking at total thrust, instead of average thrust. It's still stronger than the little ESTES motors I bought. If they don't work, I can always give them to someone that can use them.

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The E6 is a special use reloadable motor designed for rocket gliders like the OOP Aerotech Phoenix. It uses a special case that is not compatible all the 24mm reload kits. I would steer you away from that motor for the BLOBBO (or any other conventional rocket).

DANG IT ! Now would be a good place to have the Delete Post function available. Apogee sells an E6 Medalist motor, I was referring to the Aerotech E6 motor. :blush: I have no experience with the Apogee motor. Sorry for the confusion Caley, but I agree with David. Apogee says "... designed for small and lightweight rockets. When used in that kind of rocket, you can achieve altitudes over 3000 feet. The E6 is not recommended for large or heavy rockets - the low thrust makes an unstable liftoff." I would talk to customer service before buying but, in general, you want motors with double digit average thrust for the BLOBBO.

I did a little quick figuring using the "Guide" section on ThrustCurve.
The Guide section allows you to input your rockets diameter,dry weight, motor mount diameter, motor mount length and a few other parameters.
This is what I came up with for single use motors:

Motor Weight Launch Velocity Accel Altitude Time Delay

OK AeroTech E30 11.7oz 54ft/s 303ft/s 13.8G 820ft 6.5s 5s
OK AeroTech F44 11.9oz 60ft/s 349ft/s 18.5G 855ft 6.5s 6s
OK AeroTech F32 12.5oz 56ft/s 371ft/s 16.0G 1,129ft 7.5s 6s


Above are the single use motors that should work safely.

Below are the motors you should avoid:

Motor Reason
failedG Estes C11 speed at end of launch guide too slow (32ft/s)
failedG Estes D12 speed at end of launch guide too slow (36ft/s)
failedG Estes D11 speed at end of launch guide too slow (35ft/s)
failedG Quest D8 speed at end of launch guide too slow (33ft/s)
failedG Estes E12 speed at end of launch guide too slow (39ft/s)
failedG Estes E9 speed at end of launch guide too slow (28ft/s)
failedG AeroTech E20 speed at end of launch guide too slow (46ft/s)
failedG Ellis E12 speed at end of launch guide too slow (38ft/s)
failedG Apogee E6 speed at end of launch guide too slow (31ft/s)
failedG RV E15 speed at end of launch guide too slow (38ft/s)
failedG AeroTech E6 speed at end of launch guide too slow (31ft/s)
failedG AeroTech E15 speed at end of launch guide too slow (39ft/s)
failedG AeroTech F30 speed at end of launch guide too slow (43ft/s)
failedG AeroTech F21 speed at end of launch guide too slow (44ft/s)

Mike L. I talked with Apogee, and they re-did my order with different motors. Hopefully the only one they had available, an AeroTech E30T-7 will be ok. I noticed that you listed a five second delay in your list, which was not available. Hopefully this new order will be adequate. Caley Ann

Caley...depending upon the type of motor, you can get the Aerotech Delay drilling tool from Apogee and drill the delay to that which you need. Buy a 10, drill to 8...etc so on.

I don't know if you can drill out the delay on a single use motor. I just looked, and what I saw at Apogee was a drilling thing for reloadable motors. If single use motors can be drilled, I wonder if I could just use a regular drill bit. But the one single use composite motor I have has a plastic cap over the ejection area. I am guessing that is to keep the material inside just like you would have to do if you were preparing ejection charges for dual deploy.

I do plan on obtaining reusable casings and reloads eventually, even for my Blobbo, or other 24mm sized airframes. I am assuming that it is a good investment to do this, because you eventually recoup the cost of the reusable casings with the savings in reload costs.

Caley said:

I don't know if you can drill out the delay on a single use motor. I just looked, and what I saw at Apogee was a drilling thing for reloadable motors. If single use motors can be drilled, I wonder if I could just use a regular drill bit. But the one single use composite motor I have has a plastic cap over the ejection area. I am guessing that is to keep the material inside just like you would have to do if you were preparing ejection charges for dual deploy.

I do plan on obtaining reusable casings and reloads eventually, even for my Blobbo, or other 24mm sized airframes. I am assuming that it is a good investment to do this, because you eventually recoup the cost of the reusable casings with the savings in reload costs.

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Personally I wouldn't go there. I just drill out reloads. Others may know something I don't but......

I am learning a lot more about the motors.

Whomever designed the Stretch Blobbo, probably thought the builder would use a tiny bit of wood glue, and keep everything stock to keep it within the 6.7 ounce weight range listed on the kit. My dry weight is 10.8 ounces

I finally got my first shipment from Apogeee, and again, most of what I ordered, ended up just being thrown into the parts box for future builds. I'm still learning how things look in person, versus those perfect photos at the stores.

I got my motor retainer, and managed to remove the stock springy one by just taking a pair of pliers that really grip well, and started twisting it into a corkscrew. Since it is springy type steel, it stayed together, and eventually I heard the front end pop out of the motor tube, and it all slipped out fairly easily. I did a little tube repair by using a metal rod to smooth the inside of the tube. I also used CA to strengthen the aft end of the tube, as it was very weak. I then sanded to ensure everything was smooth.

I next need to remove the motor block. I watched the Apogee video, though this motor block is a black, thin walled type. It may take a lot of patience to get it done. But I hope that by the time I finish, I will have a motor tube that can take up to 120mm engines. This gives me much greater flexibility. Still, the only problem I see are the delay times are still quite long. This model is no lightweight for it's size. After apogee, it is going to fall very fast. I think anything over 3-5 seconds, and it is an automatic lawndart.

Success! The motor block ring is history, and now this airframe can take longer motors, which means more variety. Now I just have to wait until TARC stops cleaning out all the available sources, so pedestrian types like myself can get a couple to play with.

Caley said:

Success! The motor block ring is history, and now this airframe can take longer motors, which means more variety. Now I just have to wait until TARC stops cleaning out all the available sources, so pedestrian types like myself can get a couple to play with.

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Very nice!

I just got my second Apogee shipment today with the RocketEpoxy I needed to start building. The process looks pretty straight forward. I will have to wait a week or so until I finish with my next surgery. I still need blue and regular masking tape so I can mask/hold things.

This thread should probably reside in the mid-powered section. Not sure why a moderator hasn't moved it there. I made the mistake of introducing myself here, because I was eventually going to do a L1 Cert. But I mixed in the Blobo stuff. Sorry about that. Caley Ann

Caley said:

I just got my second Apogee shipment today with the RocketEpoxy I needed to start building. The process looks pretty straight forward. I will have to wait a week or so until I finish with my next surgery. I still need blue and regular masking tape so I can mask/hold things.

This thread should probably reside in the mid-powered section. Not sure why a moderator hasn't moved it there. I made the mistake of introducing myself here, because I was eventually going to do a L1 Cert. But I mixed in the Blobo stuff. Sorry about that. Caley Ann

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Caley to get the thread moved you will most likely need to contact an admin to make it happen. However they may read your post and go ahead and do it ( no garuntees).

Sorry it took so long to drop in and say "Welcome"... I was working quite a bit the week before last, then on a training trip to Jinan.

Welcome!

I guess it's all fine as is. I was saying high to the high powered boys and girlz, and just got carried away. I've been told I am a bit over enthusiastic sometimes.

Hi K'Tesh, and thanks for the welcome. The people here have taught me so much in so little time. I really wish I had held back on the Blobbo. I would've probably put in a 29mm motor mount right off the bat. That way I could use a 24mm adapter to use the smaller engines. I'm stuck with 24's, but things are better than just this morning, with the modifications I performed. I'm sure I will still be begging for help.

Today, I tried to use the RocketEpoxy. I was expecting it to be a little runny, but what I got were two tubs that are congealed into nearly solid masses. I had to dig hard with a popsicle stick to scoop a tiny bit of each onto a cardboard square. I spent a couple of minutes getting it to mix with each other. Getting that done takes some muscle, as both parts are so hard initially. I eventually got a very stiff paste, which in itself is very difficult to move around with popsicle sticle. I need to find another method of applying the goop to those places where I need it. I finally got the Blobbo motor tube surrounded by the epoxy. I then had to use a paper towel to remove most of the excess, as I is, as I said, not easy to place a very thin coat. I managed to install my new 24mm AeroPack motor retainer. Looks like it did an ok job.

Overall, I really don't like this RocketEpoxy because it is so difficult to work with. Like I said, just scooping out a very tiny bit of each part was a chore due to how it has cured in the pot. I get the feeling that the shelf life is not going to be very long here in the high desert.

I think I will purchase the normal 10 minute epoxy from a hobby store for most of my building. This RE might be ok for fillets, though maybe not. CaleyAnn

RocketEpoxy is usually in a peanut butter consistency, at least mine is and I've had it for nearly a year. I do live in the Northeast and my basement work area is usually around 65-68 degrees. I used to use mostly Bob Smith's 30 minute epoxy but I really like the RocketPoxy for fillets now, not nearly as runny as the BS stuff. When spreading it for fillets dip your popsicle sticks in alcohol to help with a smooth pull.

There's a learning curve with any new epoxy....but it's not too bad to get used to. Rocketpoxy is thick, and sort of a pain in the butt, but that thickness makes buttery smooth fillets possible

Those should not be hard at all. Like peanut butter as said before. If you have to dig hard contact the vendor and replace it. It's awesome stuff. The white won't run but the beige will droole off the stick.

I will try it on the fillets. It might be that I am just not as strong as you Guys, One pot is about as you described, but the other is the consistency of stiff taffey.

On mine, the brown half is much firmer than the white. One warning, I was sloppy and got some on the threads of the cap. That makes opening the jars a true nightmare.

David is 100% correct in getting the epoxy on the threads. Only the cream one. I've never had the issue on the white one. So real quickly things I've learned from these folks here when I started with this. (Here's a couple of oddball pics from different projects using RocketPoxy for fillets.
1. weigh in equal parts.
2. mix thoroughly and then spread thinly to reduce bubbles:


3. Tape along the fin and body tube on all fins. then go play around on TRF and allow some time to pass. Maybe 20-30 minutes (that's what I do).
4. Pour a little alcohol (Isopropyl not the fun stuff) in a bowl and then get a goop of epoxy on a popsicle stick and fill that well area.

5. Making a really flat angle, pull along the entire length of the fin.
6. Clean it off on a paper towel, dip it in alcohol, slightly increase the angle and pull again.
7. Here's on of my daughter doing her Mega Max near the end. Note the angle is now pointing downward causing a much smaller fillet to be produced by the tip of the popsicle stick.


finished fillets


One thing I'm not sure was mentioned but you may have picked up on. Don't put the rear CR ring in until after you have the fins set on the MMT. Then you have the chance to create internal fillets on the inside where the fin tabs meet the MMT tube. Then seal the end. Hope any of this is helpful, I've learned it from everyone on this board.

A while back I mentioned I would love to try building the Madcow Torrent, which can be used for both L1 and L2. Welllll...., it is no no longer available. I think Madcow has discontinued this model, and other online stores have sold out.

So, what model will fit both L1 and L2? I may never pursue L2 cert, but I wish to keep that open just in case.

Should I find a kit that has a 54mm motor mount, and purchase a 38 to 54 adapter? If I remember correctly, some 54mm engines are L1 compatible.

Right now I am looking for advice on where to start. I still haven't flown yet. Still trying to pull all the parts together to get a mid powered model in the air, but would like to start planning for L1. Caley Ann

Caley said:

A while back I mentioned I would love to try building the Madcow Torrent, which can be used for both L1 and L2. Welllll...., it is no no longer available. I think Madcow has discontinued this model, and other online stores have sold out.

So, what model will fit both L1 and L2? I may never pursue L2 cert, but I wish to keep that open just in case.

Should I find a kit that has a 54mm motor mount, and purchase a 38 to 54 adapter? If I remember correctly, some 54mm engines are L1 compatible.

Right now I am looking for advice on where to start. I still haven't flown yet. Still trying to pull all the parts together to get a mid powered model in the air, but would like to start planning for L1. Caley Ann

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Try the MadCow cardboard SuperDX3 with optional A/V bay. I built this for my L1 bird and a friend built the Torrent. They are close to being the exact same rocket. Easy to build, can fly 38mm J motors, and is well documented. If it's available, it should be a great rocket for you. (Although, I wish I'd swapped out the motor mount and centering rings for a 54mm). I believe this kit comes in Fiberglass too.

For reference, I hit 1024 ft on an H123 , which meant no need for dual deployment on my cert flight (low, slow, and simple).

I'm not in a position to offer advice as I'm basically in the same situation you are as a BAR. I can, however, offer encouragement! I've picked up a ton of info from these forums and the people here. I think the most important thing I've learned is to have fun with it! Best of luck!!!

tHoagland, That does look like the perfect alternative. It is what I looked at carefully at the Madcow website. After all the upgrades, etc, things are looking around $250+. What is funny is even with the EBAY option checked, they don't have another pop-up offering a drogue chute with Nomex protector. I guess most people opt for the basic model without upgrades. I tend to look forward to the possibility I will need more than I thought, and consequently purchase everything needed to attain that possibility.

Conwayte, Thanks so much. Best wishes to you on your journey of rocket flight. Caley Ann

Caley said:

tHoagland, That does look like the perfect alternative. It is what I looked at carefully at the Madcow website. After all the upgrades, etc, things are looking around $250+. What is funny is even with the EBAY option checked, they don't have another pop-up offering a drogue chute with Nomex protector. I guess most people opt for the basic model without upgrades. I tend to look forward to the possibility I will need more than I thought, and consequently purchase everything needed to attain that possibility.

Conwayte, Thanks so much. Best wishes to you on your journey of rocket flight. Caley Ann

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I think I flew mine with a 12" (or 16" ) drogue.
If you're adding up your total purchase/expenses, don't forget to add motor retention (I used Aeropak and JB Weld ), a motor casing/closures, and possibly, a 54-38mm adapter.