Kosdon stuff

[UPscaler]

does anyone have a 38mm kosdon stuff they want to part with?

[Sgt Blowfly]

PM sent

[MarkII]

Kosdon motors are sized in inches, not millimeters.

[GRIFFIN]

Kosdon motors are sized in inches, not millimeters.

???????

[MarkII]

???????

http://home.swbell.net/sbaughmn/docs/KOSDON98.pdf

[cjl]

It's the same standard sizes though. 3" = 75mm, 2.1" = 54mm, etc.

[rocketsmith]

Mark II is just making sure we know that he knows that Kosdon is different. In fact, it seems no matter how insignificant the detail, Mark II is always there to let us know that he knows that we are wrong.

[JDcluster]

The motor size that makes the biggest difference not being Metric is the 1" motors & not 24mm.
One inch is 25.40mm, 3" is actually 76mm . 75mm= 2.95"


http://mdmetric.com/tech/cvtcht.htm

When will they learn????

Now go back to rooms & remeasure all of your hardware....



JD

It's the same standard sizes though. 3" = 75mm, 2.1" = 54mm, etc.

[MarkII]

It's the same standard sizes though. 3" = 75mm, 2.1" = 54mm, etc.

True, but 2.5"?

[MarkII]

Mark II is just making sure we know that he knows that Kosdon is different. In fact, it seems no matter how insignificant the detail, Mark II is always there to let us know that he knows that we are wrong.

And I'm not going to be stopping anytime soon, either. But if you really believe that, then you have clearly overlooked the multitude of times that I have had to be corrected. Seriously, I'm just joining the conversation. Do you have a problem with that?

[UPscaler]

I think Frank was the original mid power 24mm motor maker, well at leas 1 inch anyway

The 2.5 cases intrigue me as well...

[karlbaum]

The motor size that makes the biggest difference not being Metric is the 1" motors & not 24mm.
One inch is 25.40mm, 3" is actually 76mm . 75mm= 2.95"


http://mdmetric.com/tech/cvtcht.htm

When will they learn????

Now go back to rooms & remeasure all of your hardware....



JD

Will 3" hardware easily fit in 75mm motor mounts? My 75mm motor tubes are not 3", they are in fact 2.95".

[cjl]

The motor size that makes the biggest difference not being Metric is the 1" motors & not 24mm.
One inch is 25.40mm, 3" is actually 76mm . 75mm= 2.95"


http://mdmetric.com/tech/cvtcht.htm

When will they learn????

Now go back to rooms & remeasure all of your hardware....



JD

That would be true if the motors were actually the size that they claimed to be. However, all motors claiming to be 75mm or 76mm or 3 inch are the same size (exactly). The same is true of 2.1 and 54mm, as well as 1.5 and 38mm (and 1.15 and 29mm, etc).

As for the 2.5"? That appears to be the same 64mm size as some hybrids. I believe Aeropack sells a 75-64mm adapter for them. Those are a non-standard size though, unlike the others.

[cjl]

Will 3" hardware easily fit in 75mm motor mounts? My 75mm motor tubes are not 3", they are in fact 2.95".

Yep - as I said in the last post, they aren't just close to the same size, they are exactly the same size.

[JDcluster]

The difference being tolerances.....
No motors would work with any tubing if there weren't any gaps between the tubes; Motor tubes, Liner tubes, coupler tubes...
Thermal expansion plays a part. Motor makers either use what their suppliers call it or pick names out of a hat...I don't know??

I once heard a great story back when the first large RMS motors came out. It told about how the 98mm came from vs 4" tubing. I forgot most of the details & wonder if anyone else can recant it?



JD

That would be true if the motors were actually the size that they claimed to be. However, all motors claiming to be 75mm or 76mm or 3 inch are the same size (exactly). The same is true of 2.1 and 54mm, as well as 1.5 and 38mm (and 1.15 and 29mm, etc).

As for the 2.5"? That appears to be the same 64mm size as some hybrids. I believe Aeropack sells a 75-64mm adapter for them. Those are a non-standard size though, unlike the others.

[karlbaum]

Yep - as I said in the last post, they aren't just close to the same size, they are exactly the same size.

I disagree. 3" is not 75mm. It is actually 76mm. Kosdon motors are not made from metric tube but from inch tube. They are not exactly the same size. West Coast Hybrids offered motors in either 75mm or 76mm, the 76mm had a significant discount. In my opinion to use a 3" motor you will need a 3" motor mount.

[UPscaler]

I disagree. 3" is not 75mm. It is actually 76mm. Kosdon motors are not made from metric tube but from inch tube. They are not exactly the same size. West Coast Hybrids offered motors in either 75mm or 76mm, the 76mm had a significant discount. In my opinion to use a 3" motor you will need a 3" motor mount.

You're absolutely fine! A friend of ours is a Kosdon dealer, and he flies his three inch cases in his 75mm minimum diameter rocket regularly.

[cjl]

I disagree. 3" is not 75mm. It is actually 76mm. Kosdon motors are not made from metric tube but from inch tube. They are not exactly the same size. West Coast Hybrids offered motors in either 75mm or 76mm, the 76mm had a significant discount. In my opinion to use a 3" motor you will need a 3" motor mount.

3 inch is 76mm by direct conversion, yes. However, motors which are commonly called both "75mm" and "3 inch" are the same size.

[daveyfire]

I think Frank was the original mid power 24mm motor maker, well at leas 1 inch anyway

The 2.5 cases intrigue me as well...

When Frank was originally making motors at MIT, he did them in the two diameters of tubing available: 1" and 2.5". Still does! 2.5" is a really nice size for L motors.

Note that Frank's price sheet says "All 3" motors measure 2.985" OD" -- I think that should settle that, um, debate (From the feel of it, it's drawn tubing at that diameter; nice and smooth inside and out, no machining marks.)

[AlphaHybrids]

2.5" L motors rock. I've got one that is 26" long. Just over 3200 Ns.

Edward

[JDcluster]

I was searching TRF and found this dated thread.

Do you have any casting tubes and liners for these motors?

JD

2.5" L motors rock. I've got one that is 26" long. Just over 3200 Ns.

Edward