Sub Minimum Scratch build.

[PDawg]

Sub Minimum Diameter custom build. Estes F-15-6 engine. 29mm lower tube, 24 mm upper tube. ASP Rocketry 25-29 spacers/Engine block and Fin set. Transition was done with a filet of glue. 23 inches tall. Is Sub minimum diameter the right term?

 

[lakeroadster]

That's an awesome looking bird. Pretty sure it meets the "Sub-Minimum Diameter" definition.

I did a quick and dirty Open Rocket sim....

 

[hobie1dog]

I'm interested to hear what glue that you used to form a transition?

 

[lakeroadster]

I'm interested to hear what glue that you used to form a transition?

A 29 mm to 25 mm transition... that's a pretty small glue fillet if you think about it. Wood glue would work fine.

 

[PDawg]

I'm interested to hear what glue that you used to form a transition?

Tite Bond wood glue. It took 3 layers to get that result. Best part is I used 29mm heavy duty tubes I had laying around for 12 years as an Engine tube. I almost threw those away 100 times.

 

[Adam3836]

Awesome….

 

[Rocketjunkie]

According to your sim, there is a tube around the motor so this is not sub minimum. My current sub minimum rockets are based on 18 mm Rx motors. The forward body tube has the same dimensions as the motor case. Couplers fit both the tube and motor case. Nose cones are printed. Lots of detail in this thread,https://www.rocketryforum.com/threads/18-mm-motors.158722/ including making motors and trial and error testing. (Research forum, you may not have access.) I have pictures on my other computer that I can post. Flying these rockets this weekend.

 

[lakeroadster]

Lots of detail in this thread,https://www.rocketryforum.com/threads/18-mm-motors.158722/ including making motors and trial and error testing.

Hmm.. the link you posted to the thread doesn't seem to work.

According to your sim, there is a tube around the motor so this is not sub minimum.

So is this "The" definition of sub-minimum, or "Your" definition of sub-minimum? I've searched... and can't find the definition?

Doesn't attaching fins and body tubes onto a motor violate NAR rule #2? Or is this being built in accordance to a different code, like HPR?

2. Motors. I will use only certified, commercially-made model rocket motors, and will not tamper with these motors or use them for any purposes except those recommended by the manufacturer.​

Does the manufacturer endorse using the motor as the airframe.. and is it capable of handling the loads applied to it?

Additionally... I guess I don't understand all the work for a rocket that will only fly once?

 

[Rocketjunkie]

Hmm.. the link you posted to the thread doesn't seem to work.

Works for me. Do you have research access?

So is this "The" definition of sub-minimum, or "Your" definition of sub-minimum? I've searched... and can't find the definition?

Doesn't attaching fins and body tubes onto a motor violate NAR rule #2? Or is this being built in accordance to a different code, like HPR?

2. Motors. I will use only certified, commercially-made model rocket motors, and will not tamper with these motors or use them for any purposes except those recommended by the manufacturer.​

Does the manufacturer endorse using the motor as the airframe.. and is it capable of handling the loads applied to it?

Additionally... I guess I don't understand all the work for a rocket that will only fly once?

Tripoli. These are research motors. How else can I get an 18 mm, 80 N-s motor I made the motors. Just a good way to fly them. With a pad weight just over 4 oz, no waiver needed

 

[lakeroadster]

Works for me. Do you have research access?

I don't. They don't allow oddroc scum on that side of town.

 

[PDawg]

Additionally... I guess I don't understand all the work for a rocket that will only fly once?
[/QUOTE]

Better to have Launched and Lost, than to have never Launched at all.

 

[Rocketjunkie]

Here's a pic, posted on Facebbook

 

[lakeroadster]

Additionally... I guess I don't understand all the work for a rocket that will only fly once?

Better to have Launched and Lost, than to have never Launched at all.
[/QUOTE]

I couldn't agree... less. What's the point?

 

[Sandy H.]

Better to have Launched and Lost, than to have never Launched at all.

I couldn't agree... less. What's the point?
[/QUOTE]

I generally agree that a 'fire and forget' is not generally something I'm into. I know Rocketjunkie's minimum diameter F rockets are tiny and go way high, but I also know he doesn't just throw them up on days that aren't conducive for the flights and the RSO also asks for lots of eyes. Next time I see him, I'll ask what percentage he gets back. I imagine its pretty high.

The only 'fire and forget' rockets I have built (other than the original Estes Mosquito, which can sometimes be that rocket for sure!!!) were a pair of minimum diameter 3FNC as plain as it can get rockets. A friend of mine and I used them when we got motors that may or may not have been temperature cycled. We'd drag race them and flew them a good many times before losing them. We need to build a few more, as the motors were not having CATO or delay issues, so are likely viable rocket motors, but not worth risking a true model, just in case.

For the type of rockets you build, there is no question, they should be flown under good conditions with high confidence motors. Its ok to use the Washington Post to get the logs going in the fireplace, but not the Mona Lisa. . .

Sandy.

 

[PDawg]

Better to have Launched and Lost, than to have never Launched at all.

I couldn't agree... less. What's the point?
[/QUOTE]
Don't you enjoy building and flying rockets? Having Fun is the point. I'm more about the Launch and the build , not having pretty Models sitting on display. This Rocket was cheap and relatively easy to build. It's only getting launched on a clear day, I would love to get it back. It's worth every penny even if I don't. I'm launching several rockets every weekend, it never gets old.

 

[lakeroadster]

Don't you enjoy building and flying rockets?

Well sure I do. I like the entire process, from scratch build to post launch recovery.

As TVM says, every rocket has to have a mission. For me, an essential part of the mission is recovery. Therefore, for many folks, it's not a successful flight, if you don't recover the rocket. That's why I wrote "What's the point ?"

Anybody can build and launch a rocket... but if that's where the journey ends, that falls short of the goal. A stable flight, and recovering an undamaged rocket, post launch... that's where all the hard work and dedication pays off.

 

[PDawg]

Anybody can build and launch a rocket... but if that's where the journey ends, that falls short of the goal. A stable flight, and recovering an undamaged rocket, post launch... that's where all the hard work and dedication pays off.
[/QUOTE]

Well I'm glad you figured out what you like. I hope to recover every rocket, and always want a straight and stable flight. If all I ever did was launch low flyng A engine rockets for fear of losing them I wouldn't even bother with Model Rockets. . I launched 3 rockets already this weekend. One fell in water, recovered, ruined, rebuilt using some of the parts, and is getting launched as a test rocket today, less than a 24 hour turn around with paint. One rocket was the best flight and video I ever had, one got lost in the clouds. I think I had a lot of fun, maybe I was wrong. I'm going out shortly to send up 4 more including 2 Estes Generic E2X my co-workers kids decorated. It will be their first launch and the fact they decorated them has them extra excited. I may send up a 5th E-Engined rocket if the skies are clear, and I hope to retrieve it. I'm not rich but the expense isn't even an issue, I spent more on drinks and snacks at the Cubs home opener game at Wrigley Field than the last 10 rockets I've launched. I enjoy every flight, every time, and never regret a launch. I hope I never get too serious or limited in Model Rocketry, it's too much fun. Good luck, may all your launches be stable, no Cato's, and succesfully recovered.

 

[lakeroadster]

Well I'm glad you figured out what you like. I hope to recover every rocket, and always want a straight and stable flight. If all I ever did was launch low flyng A engine rockets for fear of losing them I wouldn't even bother with Model Rockets. . I launched 3 rockets already this weekend. One fell in water, recovered, ruined, rebuilt using some of the parts, and is getting launched as a test rocket today, less than a 24 hour turn around with paint. One rocket was the best flight and video I ever had, one got lost in the clouds. I think I had a lot of fun, maybe I was wrong. I'm going out shortly to send up 4 more including 2 Estes Generic E2X my co-workers kids decorated. It will be their first launch and the fact they decorated them has them extra excited. I may send up a 5th E-Engined rocket if the skies are clear, and I hope to retrieve it. I'm not rich but the expense isn't even an issue, I spent more on drinks and snacks at the Cubs home opener game at Wrigley Field than the last 10 rockets I've launched. I enjoy every flight, every time, and never regret a launch. I hope I never get too serious or limited in Model Rocketry, it's too much fun. Good luck, may all your launches be stable, no Cato's, and succesfully recovered.

Go Bears..

 

[Kelly]

So is this "The" definition of sub-minimum, or "Your" definition of sub-minimum?

I think the generally accepted definitions are:
Minimum diameter: A rocket where the biggest-diameter body tube is just big enough to contain the motor diameter.
Sub-minimum: A rocket where the biggest diameter body tube (OD) is no larger than the motor diameter.

So, the build under discussion would be minimum - since its largest body tube has an OD larger than the motor OD, but is just enough to contain the motor - but not sub-minimum.

 

[PDawg]

Launched and lost for now, I was able to track it thanks to an 8 foot mylar streamer.
View attachment IMG_4041.MOV

 

[BABAR]

There is some middle ground perhaps, between sub minimum diameter and single use.

if you glue fins on the motor, the glue joint for sure is single use, but you could use a heat gun and get the fins off to glue on to another motor and rocket. And the body tube, shock cord, streamer, and nose cone could easily be reused. I am not knowledgeable about how the motor and fin “unit” is ATTACHED to the identical size motor (at least for non-reloads or other motors with bulkhead.). Maybe tape? Anyway, as long as it has a recovery device, a field big enough TO recover it, I don’t see anything wrong with it. Theoretically I theeeeenk this gives you the best chance for maximum altitude for a given motor?