Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > The Doctor is In! > Ask the Doctor
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 05-31-2015, 12:55 PM
dogcaller dogcaller is offline
Junior Rocketeer
 
Join Date: Jan 2009
Posts: 16
Default How to repair engine mounting system in Big Bertha

Hi all,

I'm a VERY casual builder and claim no expertise. My engine mount in my Big Bertha was damaged and needs to be replaced. I managed to get the unit out, but I don't know how to replace it. Does Estes sell replacement parts like that? Also, I can't quite remember the build. I'm assuming I just put glue on the cardboard washer things and position the unit in place to dry in the body tube. Is that right...?

Thanks!
Reply With Quote
  #2  
Old 05-31-2015, 01:16 PM
A Fish Named Wallyum A Fish Named Wallyum is online now
BP Mafia
 
Join Date: Mar 2005
Location: Ft. Thomas, KY
Posts: 8,596
Default

Sand as much of the old glue and cardboard from inside the tube as possible, then rebuild the mount and slide it in. This would be a good time to upgrade the recovery system if you have a mind to with Kevlar. The parts should be easy to find. Two CR-2060 rings, an 18mm engine hook, a 520 engine block and a length of BT-20 would be all you need. As for length on the BT-20, the normal 2.75" length should work fine, but some opt for a longer piece of BT-20 to fill a little more of the Bertha body tube to make it easier for the ejection charge to push out the recovery system. Check Semroc for the parts. If you want to go the Kevlar route, PM me with your address and I'll sent you a yard. I have a "little" extra.
__________________
Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Centuri Design Contest F-150 Hurricane Estes - Low Boom SST Semroc - Gee'Hod, Shrike, SST Shuttle

In paint: Canaroc Starfighter Scorpion Estes F-22 Air Superiority Fighter, Solar Sailer II Semroc Cyber III

Ready to fly: Estes - Multi-Roc, Solar Sailer II Semroc - Earmark, Snake Jumper
Reply With Quote
  #3  
Old 05-31-2015, 04:55 PM
Doug Sams's Avatar
Doug Sams Doug Sams is offline
Old Far...er...Rocketeer
 
Join Date: Mar 2005
Location: Plano, TX resident since 1998.
Posts: 3,965
Default

Quote:
Originally Posted by A Fish Named Wallyum
Sand as much of the old glue and cardboard from inside the tube as possible, then rebuild the mount and slide it in. This would be a good time to upgrade the recovery system if you have a mind to with Kevlar. The parts should be easy to find. Two CR-2060 rings, an 18mm engine hook, a 520 engine block and a length of BT-20 would be all you need. As for length on the BT-20, the normal 2.75" length should work fine, but some opt for a longer piece of BT-20 to fill a little more of the Bertha body tube to make it easier for the ejection charge to push out the recovery system. Check Semroc for the parts. If you want to go the Kevlar route, PM me with your address and I'll sent you a yard. I have a "little" extra.
Dogcaller, You can't get a much better description of the repair than that. That said, my only different thought is to upgrade to a larger motor mount. So that'd be a BT-50 tube with CR-50-60 rings. But otherwise about the same process.

With that, you can fly some D motors, and maybe some E's. But it goes way up there on a D12, and about out of sight on E's, so take some young eyes with you to the rocket range

Doug

.
__________________
YORF member #11
Reply With Quote
  #4  
Old 05-31-2015, 04:57 PM
MarkB.'s Avatar
MarkB. MarkB. is offline
Surfrajettes Fan
 
Join Date: Feb 2008
Location: El Paso
Posts: 1,113
Default

Not to rain on the parade,

Didn't the older/original Big Berthas have an engine mount that included a coupler between the centering rings? If you look inside and see a short length (about 2") of black phenolic or unsealed paper tubing, then you may have to go a different route replacing the engine mount.

If you have such a piece in there, then I'd use a longer stuffer tube and preglue the top centering ring in place (with some kevlar like Bill suggested) and then slide this down from the top of the body tube to meet the lower centering ring glued in place at the bottom. It might be a little tricky but doable.
__________________
NAR 79743
NARTrek Silver
I miss being SAM 062

Awaiting First Launch: Too numerous to count
Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard
Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774
On the Bench: 2650;
Dream Stage: 1/39.37 R-7
Reply With Quote
  #5  
Old 05-31-2015, 07:13 PM
Ltvscout Ltvscout is offline
Ye Olde Rocket Shoppe
 
Join Date: Jun 2004
Location: Milwaukee, WI
Posts: 6,472
Default

Quote:
Originally Posted by Doug Sams
Dogcaller, You can't get a much better description of the repair than that. That said, my only different thought is to upgrade to a larger motor mount. So that'd be a BT-50 tube with CR-50-60 rings. But otherwise about the same process.

With that, you can fly some D motors, and maybe some E's. But it goes way up there on a D12, and about out of sight on E's, so take some young eyes with you to the rocket range

A Mini-Broadsword.
__________________
Scott D. Hansen
Ye Olde Rocket Shoppe - Your One Stop BAR Shoppe!
Ye Olde Rocket Plans - OOP Rocket Plans From 38 Companies!
Ye Olde Rocket Forum
WOOSH NAR Section #558
Reply With Quote
  #6  
Old 05-31-2015, 07:16 PM
jdbectec jdbectec is offline
the middle-aged rocketeer
 
Join Date: Sep 2006
Location: Urbana, Illinois.....the birthplace of HAL
Posts: 468
Default

Quote:
Originally Posted by MarkB.
Not to rain on the parade,

Didn't the older/original Big Berthas have an engine mount that included a coupler between the centering rings? If you look inside and see a short length (about 2") of black phenolic or unsealed paper tubing, then you may have to go a different route replacing the engine mount.

If you have such a piece in there, then I'd use a longer stuffer tube and preglue the top centering ring in place (with some kevlar like Bill suggested) and then slide this down from the top of the body tube to meet the lower centering ring glued in place at the bottom. It might be a little tricky but doable.



Wow! you're really going way back! for many years the Big bertha mount has been a BT-20B(8 5/8") and 2 centering rings, with a motor hook. I recall buying a Big Bertha starter set around 1990 and it having that set-up. I believe the coupler disappeared sometime circa 1980's.
__________________
Jeffrey Deem
NAR16741
CIA section 527
Reply With Quote
  #7  
Old 05-31-2015, 07:24 PM
jdbectec jdbectec is offline
the middle-aged rocketeer
 
Join Date: Sep 2006
Location: Urbana, Illinois.....the birthplace of HAL
Posts: 468
Default

Quote:
Originally Posted by jdbectec
Wow! you're really going way back! for many years the Big bertha mount has been a BT-20B(8 5/8") and 2 centering rings, with a motor hook. I recall buying a Big Bertha starter set around 1990 and it having that set-up. I believe the coupler disappeared sometime circa 1980's.

Here's what I bought then:

http://www.spacemodeling.org/JimZ/estes/est1948.pdf
__________________
Jeffrey Deem
NAR16741
CIA section 527
Reply With Quote
  #8  
Old 05-31-2015, 07:48 PM
MarkB.'s Avatar
MarkB. MarkB. is offline
Surfrajettes Fan
 
Join Date: Feb 2008
Location: El Paso
Posts: 1,113
Default

Yes, Yes . . . I go waaay back . . . I know, I know. . . I'm old.

Trust me, I know.
__________________
NAR 79743
NARTrek Silver
I miss being SAM 062

Awaiting First Launch: Too numerous to count
Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard
Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774
On the Bench: 2650;
Dream Stage: 1/39.37 R-7
Reply With Quote
  #9  
Old 05-31-2015, 08:00 PM
luke strawwalker's Avatar
luke strawwalker luke strawwalker is offline
BAR
 
Join Date: Dec 2007
Location: Needville and Shiner, TX
Posts: 6,134
Default

Quote:
Originally Posted by MarkB.
Yes, Yes . . . I go waaay back . . . I know, I know. . . I'm old.

Trust me, I know.


LOL I was thinking like you do, Mark...

Guess my age is showing...

Later! OL JR
__________________
The X-87B Cruise Basselope-- THE Ultimate Weapon in the arsenal of Homeland Security and only $52 million per round!
Reply With Quote
  #10  
Old 05-31-2015, 09:49 PM
tbzep's Avatar
tbzep tbzep is offline
Dazed and Confused
 
Join Date: Mar 2005
Location: TN
Posts: 11,610
Default

Quote:
Originally Posted by jdbectec
Wow! you're really going way back! for many years the Big bertha mount has been a BT-20B(8 5/8") and 2 centering rings, with a motor hook. I recall buying a Big Bertha starter set around 1990 and it having that set-up. I believe the coupler disappeared sometime circa 1980's.

I believe it changed in the mid 70's from the coupler style to the current style.
The coupler style mount remained popular in several Centuri kits until the end.
__________________
I love sanding.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 03:59 PM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe © 1998-2024