Layne Pemberton contacted me a couple of weeks ago and asked if I'd be his lab rat. Expecting that I'd be injected with weird drugs and required to solve strange puzzles, I agreed. Turns out he wanted me to build a new kit he's thinking about releasing. Oh well, it was still a lot of fun. :biggrin:
I'm sure Layne will jump in and correct anything, so take anything I say with a grain of salt as far as what actually ends up in the final kit goes.
OK, the Screamin' Green Meanie is Pem Tech's first foray into the Skill 1, stubby rocket market. It has 3 combination ring and conventional fins, is BT80 sized, and has a 24mm MMT. The 1/8" balsa fins are laser cut, and used a nice, hard balsa stock. I'm not sure of the rating of the braided kevlar shock cord, but it looks like I could tow my car with it. There is plenty of it, too - about 4x the length of the finished rocket. There is an unassembled Hartle Engineering 16" 'chute, and 1/4" lugs. The parts were of very good quality.
Assembly was straightforward. The instructions were brief (about a paragraph) but more than adequate for a beta test. I imagine they'll get the Pem Tech Destruction treatment before release. Assembly starts with marking the lines on the airframe for the fins and lugs. After that, you cut off 3x 1" pieces of the airframe to use as the ring fins. It's important to mark the lines first as they help you line up the ring on the fin in the next step. Ask me how I know.. The instructions actually mentioned this, but I forgot by the time I got started.
Next you slip the fins into the rings and glue inplace. The fins have a groove on the root edge for the ring, making it easy to get in the right place. Glue the fins and lugs onto the airframe. While you are waiting for glue to dry on the fins, assemble the motor mount. It's the usual manner most of us use - attach the shock cord between the CRs and direct it forward via a notch in the outside of the forward CR. Note that there isn't any form of motor retention or thrust ring. Anyone that has built any other Pem Tech LPR kit would be familiar with this. I've been friction fitting my motors and I've had no problems at all. Doing it this way leaves the flyer with a great deal of choices for motor selection.
The balsa nosecone was very nice. It needed some ballast and a screweye. I drilled a hole and epoxied both in. I also CA-ed the tip to give it a little bit of extra durability.
Finishing was straightforward. I'm an "assemble -> prime -> wet sand -> colour coats -> Future" guy, and that's what I did here. I had a few more interesting looking paint schemes in mind, but I'm dodging the start of the wet season here. I didn't want to get caught waiting for a couple of weeks between coats, so jumped in with a basic scheme. With the interesting fin pattern, I'm sure everyone can come up with some inspired finishes.
I flew it twice this morning at my local junior soccer fields. It's been threatening rain, so the air was very still. I loaded up a handful or so of dogbarf and a C11-3 and let it rip. It was a great straight boost, although not super high. Maybe 100ft or so. Deployment was nose down, but it was a gentle descent and landing about 10-15' from the pad. This would be the minimum motor I would recommend for this rocket. Second flight was on a D12-3 and was another perfectly straight boost. As expected, it got a lot more air. Deployment was right at apogee. Another gentle descent with recovery about 50ft from the pad. The air was that still that as I was walking back after recovering the rocket, I found myself in a gentle shower of dogbarf raining down. That's the first time that has ever happened to me.
Conclusions? Overall, this a nice looking rocket that is easy to build and flies great. I only have a small field, so a D12 is about all I can risk. I have no doubt that this rocket would be great on a composite E. To reach the Skill 1 level, I believe Layne is changing to a plastic nosecone, and possibly precut rings.
I've been having some issues with my camera, and true to form it went screwy just as I was about to launch, so no liftoff shot.
Many thanks to Layne for giving me the opportunity build such a cool rocket. :beer:
I'm sure Layne will jump in and correct anything, so take anything I say with a grain of salt as far as what actually ends up in the final kit goes.
OK, the Screamin' Green Meanie is Pem Tech's first foray into the Skill 1, stubby rocket market. It has 3 combination ring and conventional fins, is BT80 sized, and has a 24mm MMT. The 1/8" balsa fins are laser cut, and used a nice, hard balsa stock. I'm not sure of the rating of the braided kevlar shock cord, but it looks like I could tow my car with it. There is plenty of it, too - about 4x the length of the finished rocket. There is an unassembled Hartle Engineering 16" 'chute, and 1/4" lugs. The parts were of very good quality.
Assembly was straightforward. The instructions were brief (about a paragraph) but more than adequate for a beta test. I imagine they'll get the Pem Tech Destruction treatment before release. Assembly starts with marking the lines on the airframe for the fins and lugs. After that, you cut off 3x 1" pieces of the airframe to use as the ring fins. It's important to mark the lines first as they help you line up the ring on the fin in the next step. Ask me how I know.. The instructions actually mentioned this, but I forgot by the time I got started.
Next you slip the fins into the rings and glue inplace. The fins have a groove on the root edge for the ring, making it easy to get in the right place. Glue the fins and lugs onto the airframe. While you are waiting for glue to dry on the fins, assemble the motor mount. It's the usual manner most of us use - attach the shock cord between the CRs and direct it forward via a notch in the outside of the forward CR. Note that there isn't any form of motor retention or thrust ring. Anyone that has built any other Pem Tech LPR kit would be familiar with this. I've been friction fitting my motors and I've had no problems at all. Doing it this way leaves the flyer with a great deal of choices for motor selection.
The balsa nosecone was very nice. It needed some ballast and a screweye. I drilled a hole and epoxied both in. I also CA-ed the tip to give it a little bit of extra durability.
Finishing was straightforward. I'm an "assemble -> prime -> wet sand -> colour coats -> Future" guy, and that's what I did here. I had a few more interesting looking paint schemes in mind, but I'm dodging the start of the wet season here. I didn't want to get caught waiting for a couple of weeks between coats, so jumped in with a basic scheme. With the interesting fin pattern, I'm sure everyone can come up with some inspired finishes.
I flew it twice this morning at my local junior soccer fields. It's been threatening rain, so the air was very still. I loaded up a handful or so of dogbarf and a C11-3 and let it rip. It was a great straight boost, although not super high. Maybe 100ft or so. Deployment was nose down, but it was a gentle descent and landing about 10-15' from the pad. This would be the minimum motor I would recommend for this rocket. Second flight was on a D12-3 and was another perfectly straight boost. As expected, it got a lot more air. Deployment was right at apogee. Another gentle descent with recovery about 50ft from the pad. The air was that still that as I was walking back after recovering the rocket, I found myself in a gentle shower of dogbarf raining down. That's the first time that has ever happened to me.
Conclusions? Overall, this a nice looking rocket that is easy to build and flies great. I only have a small field, so a D12 is about all I can risk. I have no doubt that this rocket would be great on a composite E. To reach the Skill 1 level, I believe Layne is changing to a plastic nosecone, and possibly precut rings.
I've been having some issues with my camera, and true to form it went screwy just as I was about to launch, so no liftoff shot.
Many thanks to Layne for giving me the opportunity build such a cool rocket. :beer:
