Reasons for Quest BT sizes?

[JRThro]

Speaking of <a href="https://www.rocketryforum.com/showthread.php?s=&postid=136486">Quest parts</a>, which I asked about in another thread, why doesn't Quest use the same sizes of BT's, NC's, etc., as most other model rocketry manufacturers?

Was it just so their tubes would have OD's of exactly 15, 20, 25, 30, and 35 mm, or were there other reasons?

Thanks.

 

[shreadvector]

Yes, they are metric round numbers. They also inherited them from previous rocket companies that had the plastic parts which Quest used in their original runs of kits. (MPC/AVI)

Originally posted by JRThro
Speaking of <a href="https://www.rocketryforum.com/showthread.php?s=&postid=136486">Quest parts</a>, which I asked about in another thread, why doesn't Quest use the same sizes of BT's, NC's, etc., as most other model rocketry manufacturers?

Was it just so their tubes would have OD's of exactly 15, 20, 25, 30, and 35 mm, or were there other reasons?

Thanks.

 

[adrian]

That then raises the question - where did Estes get their tube sizes? They aren't particularly convenient numbers of millimetres or inches, and the tube numbers don't seem to bear any relation to tube diameters.

 

[dr wogz]

Dosen't this fall into the 'we have established our own standards (in the hopes that we will [eventually] set the standard)' argument, and that these manufactureres are trying to sway teh industry towards their particular parts.

Like how VHS beat out Beta, why lumber 'measuerments' don't actually repersent their actual size. The electronics industry have been doing this for years! one part is slightly off compared to the 'comeptition' so you can't just use theirs in place of ours... AWG vs. SWG vs. British standards (Steel guages)

 

[jflis]

I think Estes part sizes came about mainly because of what materials were already available (say, for nose cones) and, perhaps, some limitation on their motor making machine (Mabel). (mind you, i'm just guessing, i don't actually know...)

Also, it seems more than coincidence that 3 BT-20 tubes fit exactly into a BT-60 and 3 BT-50 fit (nearly perfectly) inside a BT-70.

These may have also contributed to some body tube sizes.

Although, it is an interesting enough question that if I remember, next year I will ask

 

[shreadvector]

BT-60 was reverse engineered from paper towel tubes since 3 motor mount tubes (3 BT-20J tubes) fit exactly inside certain brands of paper towel tubes. Now days, most paper towel tubes are larger since that results in LESS towels on the roll. Aluminum foil core tube works great (and can be used as a coupler for paper towel tubes and as the shoulder/sleeve for the round half of 'large' Easter eggs which make great nose cones).

Originally posted by jflis
I think Estes part sizes came about mainly because of what materials were already available (say, for nose cones) and, perhaps, some limitation on their motor making machine (Mabel). (mind you, i'm just guessing, i don't actually know...)

Also, it seems more than coincidence that 3 BT-20 tubes fit exactly into a BT-60 and 3 BT-50 fit (nearly perfectly) inside a BT-70.

These may have also contributed to some body tube sizes.

Although, it is an interesting enough question that if I remember, next year I will ask

 

[OARJeepr]

Just a note on lumber dimensions. When refering to lumber widths and thicknesses, the convention is to use the rough cut dimensions. Thus when a 2x4 is cut from the log it is actually 2x4. After it is finished it ends up being ~1 3/4 x 3 1/2. If you wanted actual 2x4 you could get it, but it would be rough cut and unfinished.