38mm DoorKnob -

The Rocketry Forum

Help Support The Rocketry Forum:

Andy Greene

Well-Known Member
Joined
Jan 11, 2013
Messages
1,124
Reaction score
162
So who's is gonna do it , the 38mm upgrade for your Estes DoorKnob with the Vanderburn upgrade ??
 

Andy Greene

Well-Known Member
Joined
Jan 11, 2013
Messages
1,124
Reaction score
162
Im hoping someone else will tackle it before I start building- as of now Im going 29mm but being spoiled on flying 38mm research motors/ Im half tempted to do it.
 

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
9,834
Reaction score
1,809
Location
Pasco, WA
Im hoping someone else will tackle it before I start building- as of now Im going 29mm but being spoiled on flying 38mm research motors/ Im half tempted to do it.
Not hard to do...getting it back might be! With a 38 MMT I would double the arframe using coupler sections from Balsa Machining Service, that way it would take many of the 38mm motors without much stress.
 

Andy Greene

Well-Known Member
Joined
Jan 11, 2013
Messages
1,124
Reaction score
162
I was really just amazed they even offered it as an option- even with the upgrade plywood and 29mm , on a G80 it should be a hoot ;)
 

Andy Greene

Well-Known Member
Joined
Jan 11, 2013
Messages
1,124
Reaction score
162
Im thinking 5 inch glass tube and a 54mm mount - where is Gary T when you need him :rolleyes:
 

Philip Tiberius D.

Old Fashioned 2.5oz Rye/H2O 8 drops Orange Bitters
Joined
Oct 17, 2018
Messages
217
Reaction score
98
Location
Bixby, OK
I built one... need to dig up what motor she ran on. I have a second (unbuilt) with the Vander-Burn upgrade (love his stuff btw). I airframe buckled and fin sheared off but I believe most of that occurred on impact due to the ejection change melting the parachute cords. Aerotech G76 Mojave
F72533B7-CC9A-4ACA-B89A-D8F44E0DF717.jpeg
F72533B7-CC9A-4ACA-B89A-D8F44E0DF717.jpeg
 

Philip Tiberius D.

Old Fashioned 2.5oz Rye/H2O 8 drops Orange Bitters
Joined
Oct 17, 2018
Messages
217
Reaction score
98
Location
Bixby, OK
The build has started. Motor shown is a 54mm 620ns I100 Firestarter . 6 seconds of terror. All the extra goodies are from Mac Performance .125 canvas cut by Nat Kinsley. Motor mount is also canvas , just not in the picture.
Is that a “stock” Doorknob with MacP fins or a all MacP kit ?
 

Andy Greene

Well-Known Member
Joined
Jan 11, 2013
Messages
1,124
Reaction score
162
The build has started. Motor shown is a 54mm 620ns I100 Firestarter . 6 seconds of terror. All the extra goodies are from Mac Performance .125 canvas cut by Nat Kinsley. Motor mount is also canvas , just not in the picture.
Why canvas not
G10/12 ?
 
Last edited:

Tobor

Get your peanuts....
TRF Supporter
Joined
Oct 8, 2016
Messages
2,004
Reaction score
604
Canvas (0.769 oz/ft³) is also lighter then G10 (1.1 oz/ft³)/G12 (1.05 oz/ft³).
 
Last edited:

Nytrunner

Pop lugs, not drugs
TRF Supporter
Joined
Oct 15, 2016
Messages
7,830
Reaction score
3,501
Location
Huntsville AL
You may not even need glass on the body tube. It has no joints, the motor mount and rings will reinforce it internally down where most of the stress will be, and the tube is just short (smaller bending moments)
 

Andy Greene

Well-Known Member
Joined
Jan 11, 2013
Messages
1,124
Reaction score
162
Canvas (0.769 oz/ft³) is also lighter then G10 (1.1 oz/ft³)/G12 (1.05 oz/ft³).
Not knocking it , but Im not sure I would be real concerned about the weight difference, I have just never worked with it . If it was a huge bit cheaper maybe, thats just me, if your putting that much motor to that little rocket-
whats a few ounces ??
 

Flyfalcons

Well-Known Member
Joined
Apr 14, 2015
Messages
2,513
Reaction score
705
No glass needed, the mmt and centering rings add a ton of strength. 54mm no problem.
 

3stoogesrocketry

Well-Known Member
Joined
Feb 26, 2012
Messages
1,442
Reaction score
254
[
In a 3x18 carboard tube ??
Correct , even though it will have a layer of glass for durability in transport and if it splashes down. The buckle load or column strength of two concentric tubes inside each other is very high .[/QUOTE]
 

Andy Greene

Well-Known Member
Joined
Jan 11, 2013
Messages
1,124
Reaction score
162
So I finished mine up-it was fun to build a small cardboard/plywood kit again - I was getting spoiled on glass 4 inch stuff . Of course I changed the colors , mainly because it was what I had in leftover quarts , and Im not a big fan of the cardstock colors. Will give it a go in a few weeks on a G40/7W with the JLCR.
20210222_202921.jpg
 

Attachments

Last edited:
Top