Minimum diameter

[Tom Rouse]

Tom,

Would you make those fincans so they fit around the motor? I like fincans, but I hate the fact they fit over the body tube and increase the overall diameter and add drag (picky picky, I know).

That would cause problems with Tripoli. Having an all aluminum rocket is against the code.
Besides, what would you use for the upper payload/avionics/recovery section? Whatever you used, there would need to be a connection from the forward closure to that section. You can't modify the hardware, so you would need to come up with a crafty way of doing that.
In the final anaylsis, you would end up with the following-
1- A payload section with a diameter larger than the motor case. That frontal cross section is what your rocket would have its drag based on.
2- The weight of the coupler assembly would be close to the weight of the airframe tube you eliminate.
3- A modified forward closure.

 

[uncle_vanya]

Playing Devil's advocate...

That would cause problems with Tripoli. Having an all aluminum rocket is against the code.

TRA isn't the only game in town. Not everyone uses TRA or NAR insurance.

Besides, what would you use for the upper payload/avionics/recovery section? Whatever you used, there would need to be a connection from the forward closure to that section.

Custom tubes. Use a mandrel that results in a motor sized tube.

You can't modify the hardware, so you would need to come up with a crafty way of doing that.

For non-commercial non-TRA/NAR flights why is this an issue? Just fly on a custom motor...

In the final anaylsis, you would end up with the following-
1- A payload section with a diameter larger than the motor case. That frontal cross section is what your rocket would have its drag based on.

Even if this was the case, the reduction of diameter at any time reduces the total surface area and isn't a bad thing...

2- The weight of the coupler assembly would be close to the weight of the airframe tube you eliminate.

True but this was not really about weight. There may be ways to do this that do not add as much weight as the composite tube eliminated - particularly for really long and beefy motors.

3- A modified forward closure.

Maybe... or one designed for this purpose from the start.

 

[AKPilot]

I simply like having a rocket I can get my hands into and around.

 

[Chrisn]

I simply like having a rocket I can get my hands into and around.

So you mean you like big minimum diameter rockets?

 

[Hospital_Rocket]

So you mean you like big minimum diameter rockets?

Last I heard Troy was building a 6" MD for his next Cert.

P7000 or so on 6" CF. I heard he was discussing launching at the local schoolyard. after telling the authorities it was a rocket that ws barely larger thab the motor., Of course his demo motor at the hearing was a D12-5.

 

[MarkII]

Looks like the 'love 'em' choice is winning..I voted for the 3rd option as I have a love/hate relationship with minimum diameter rockets..Like 'em for the looks but hate them when trying to stuff the wadding/shock cord and streamer/chute in the tube(ESPECIALLY if they are 13mm or 18mm min dia)..I have some clumsy hands and it never fails: I get the shock cord in and then try to put the streamer/chute in I end up pulling the shock cord back out!

Jon,

A little advice from someone who likes to fly minimum diameter MicroMaxx rockets (among others): use a dowel, pencil, or something similar to stuff the recovery system into the upper part of the BT. Keep one in your range box, and make sure that it fits quite loosely into the tube. (If it is too snug, it will drag the shock cord back out with it when you pull it out.) Make sure that your parachute or streamer is rolled just tight enough (but not too tight) that it will not bind and get hung up against the inside of the tube. Use talc or cornstarch to help with getting the laundry out at the appropriate time (this also helps with tracking). To keep from pulling the shock cord back out while you are wrestling with the streamer or chute, leave the tamping tool in place in the BT until you are ready to push in the recovery device. I usually roll up the chute/streamer first, and then temporarily clamp it with a springy clothes pin to keep it from unraveling again while I gather up the rest of the shock cord. I get everything else stuffed in first, and then take the clothes pin off and stuff the recovery device in last.

Mark \\.