Go Back  RCU Forums > RC Airplanes > Kit Building > Kit Manufacturer Direct Support Forum
Reload this Page >

Need Goldberg Tiger 2 Information

Notices
Kit Manufacturer Direct Support Forum Get support here directly from the manufacturers themselves or their official reps for the kits they manufacture or distribute.

Need Goldberg Tiger 2 Information

Old 01-06-2017, 09:03 AM
  #1  
Roodester
Member
Thread Starter
 
Join Date: Jan 2003
Location: Grove City, PA
Posts: 96
Likes: 0
Received 0 Likes on 0 Posts
Question Need Goldberg Tiger 2 Information

Hi Everyone,
I am presently building a Goldberg Tiger 2 (40) kit to replace my previously owned one which I flew until it simply fell apart (just literally wore out).

The plywood wing dihedral gauges that come with the kit are a bit "shaky" and I am concerned that I will not build in the proper dihedral. Nowhere on the plans nor instructions is there any information about the:

dihedral angle
down thrust angle
right thrust angle

Does anyone have those specifications? I realize that they are build into the construction of the plane but I would like to check them to be sure they are accurately placed.

Thanks
roodester
Old 02-11-2017, 08:27 AM
  #2  
markfsanderson
 
markfsanderson's Avatar
 
Join Date: Nov 2003
Location: Castle Hills, TX
Posts: 102
Likes: 0
Received 0 Likes on 0 Posts
Default

Roodester,
I'm not familiar with the Goldberg Tiger 2, but I've I've built some of the SIG and Great Planes kits before. On my Trainer 40 plans, they had the height of the wing tip when the wing is assembled and one wing is flat against a table. Given that measurement, the wing half length and length from the spot on the table to the wing root you will find the dihedral brace angle.
I've read elsewhere that a 3 degree right thrust angle is a good staring point - but not sure where I read it. I wouldn't worry about down thrust for now . . . I don't believe its critical? Not 100% sure . . . .

dihedral: http://mathcentral.uregina.ca/qq/dat...7/h/lucy1.html If you know A/P (that height I mentioned), b is the main strut length to the point where you drop the line to the table, and then mark that position and measure P/C (a). Plug in the numbers and you get the angle. Obviously, the actual angle is 1/2 this value for the dihedral brace.



Mark
Old 02-11-2017, 01:29 PM
  #3  
Roodester
Member
Thread Starter
 
Join Date: Jan 2003
Location: Grove City, PA
Posts: 96
Likes: 0
Received 0 Likes on 0 Posts
Default

Hi Mark

Thank you for the information. Here's what I've done. There is a jig that came with the kit that holds the root above the plans. I noticed that when the wing was in place inverted, the wingtips touched the plans which meant that the wingtip was 1" (the jig is one inch high) above the root or 2" if one wing held flat on the board. Taking the length of one wing, I plugged it into the math equation tangent=opposite side/adjacent side. I simply took the co tangent of that number and came up with 2 degrees. So after all that, I simply built the plane as per the plans and it looks good so I'm satisfied.

As for the down thrust and right thrust, I simply measured the angle off of the plans. 3 degrees down thrust and 1 1/2 degrees (I then noticed the plans said 2 degrees "right offset" - that answer was just sitting under my eyes, duh). The down thrust appears to be built into the firewall so I followed the directions closely and will assume all is well. The right thrust is adjustable with some washers under the motor mount.

The plane is going together well. But I am a slow builder and I doubt I'll have it done before summer. It's the building that is fun. I have other planes to fly.

Thanks Phil
Old 02-11-2017, 03:01 PM
  #4  
markfsanderson
 
markfsanderson's Avatar
 
Join Date: Nov 2003
Location: Castle Hills, TX
Posts: 102
Likes: 0
Received 0 Likes on 0 Posts
Default

Cool! Phil make sure you publish some pix if you'd like . . . you are motivating me to start on my 2 Trainer 40 kits that I purchased off of eBay. A bit of an advance trainer; that I've been out of RC airplanes for a while I'll be starting with a Basic Trainer ARF. My plan is to put an OS 52/56 SF Surpass Four Stroke in one and electrify the other . . . I just discovered that I have two kits, but 3 plans . . . I was puzzled as to why they discontinued this kit . . . a great flyer for sure.

Have Fun and Good Luck!

Mark

Last edited by markfsanderson; 02-11-2017 at 03:03 PM.
Old 02-12-2017, 07:31 AM
  #5  
spaceworm
 
Join Date: Mar 2009
Location: Guilford, CT
Posts: 3,950
Received 2 Likes on 2 Posts
Default

[QUOTE=markfsanderson;12305156]..., the wing half length and length from the spot on the table to the wing root you will find the dihedral brace angle.
I've read elsewhere that a 3 degree right thrust angle is a good staring point - but not sure where I read it. I wouldn't worry about down thrust for now . . . I don't believe its critical? Not 100% sure . . . ].

FWIW. Trainer 40 (Bridi?) Has full symmetrical wing?. My Bridi Trainer 60 did. Mine had a flat, no-dihedral wing, but very effective ailerons. It was a great second plane for beginners.

Dihedral is added for stability and self righting characteristics. Three channel planes need it for turning with rudder only. Right thrust is added to counter torque thrust turns to the left and is desirable for takeoffs and high torque engines., Down thrust is applicable to flat or semi-symmetrical wing airfoils, and is added to counter those airfoil types tendency to bloom on application of power. I just thought Io would express it all simply in my understanding, there is more to it all of course.
Old 02-12-2017, 08:41 AM
  #6  
markfsanderson
 
markfsanderson's Avatar
 
Join Date: Nov 2003
Location: Castle Hills, TX
Posts: 102
Likes: 0
Received 0 Likes on 0 Posts
Default

[QUOTE=spaceworm;12305388]
Originally Posted by markfsanderson View Post
..., the wing half length and length from the spot on the table to the wing root you will find the dihedral brace angle.
I've read elsewhere that a 3 degree right thrust angle is a good staring point - but not sure where I read it. I wouldn't worry about down thrust for now . . . I don't believe its critical? Not 100% sure . . . ].

FWIW. Trainer 40 (Bridi?) Has full symmetrical wing?. My Bridi Trainer 60 did. Mine had a flat, no-dihedral wing, but very effective ailerons. It was a great second plane for beginners.

Dihedral is added for stability and self righting characteristics. Three channel planes need it for turning with rudder only. Right thrust is added to counter torque thrust turns to the left and is desirable for takeoffs and high torque engines., Down thrust is applicable to flat or semi-symmetrical wing airfoils, and is added to counter those airfoil types tendency to bloom on application of power. I just thought Io would express it all simply in my understanding, there is more to it all of course.
Spaceworm,
Nope, Great Planes Trainer 20/40/60 (NOT PT 20/40/60) were advanced trainers that GP discontinued in the mid-nineties. Designed by Bridi? Not sure. I've recently purchased two unbuilt Great Planes Trainer 40 kits off of eBay that appear to be complete (except one doesn't have a manual, but it has two sets of plans!) It had some faults; lack of dihedral brace (had to cut and fit your own as they relied solely on the glassing to keep it together). I had to employ a similar approach that I described above to create and utilize a dihedral brace. Also, the tail section was weak enough such that you might damage it during sudden high-G maneuvers. Simple reenforcement of the tail 'box section' (am I describing it correctly with the right terms?) prevented that. I was introduced to the dihedral brace issue while flying in Houston with my Royal 40 Engine . . . the wings snapped in two, gently floated back down to earth while the fuselage took a screaming dive and buried itself 6 inches into soft earth. Rebuilt everything and flew later that month . . . By the time I finally retired that bird it was probably carrying an extra pound of epoxy! But I was having great fun with my SIG Four Star 40 . . . another fantastic aircraft still being produced in kit form (thank god).

Stalls, spins, loops, immelmans, inverted flight, snap rolls, and etc were a breeze . . . With the Royal I couldn't hold any knife edges . . . but the OS 46 did them with no problems.

My hope is to have fun with an ARF trainer while building the Trainer 40, but an OS52/56 SF Four Stroke on one and electrify the other while re-learning flying at a local AMA field here in the SATX area . . . Good fun!


Mark!
Old 02-12-2017, 01:00 PM
  #7  
spaceworm
 
Join Date: Mar 2009
Location: Guilford, CT
Posts: 3,950
Received 2 Likes on 2 Posts
Default

The Trainer 40 was originally the RCM Trainer (see picture attached) it was marketed by Bridi and called the RCM Bridi Trainer. Bridi also marketed a kit of an enlarged version, called the Trainer 60 (which I had), Kraft also had a version of the 40 called the Krafty. GP picked up the rights and marketed theirs. There is a wealth of info on the RCU Forums. Just use RCM Trainer, or Bridi Trainer 40, and you will bring up the history. I think they are all basically the same plane, except the first versions had a rubber banded wing and later it was bolt on. Other subtle changes for manufacturability were made I am sure. It was a great design that would still be so today. There are good plans on one of the RCU sites. Enjoy yours.

Sincerely, Richard
Attached Thumbnails Click image for larger version

Name:	RCM-Trainer1.jpg
Views:	199
Size:	58.2 KB
ID:	2200765  
Old 02-12-2017, 09:27 PM
  #8  
markfsanderson
 
markfsanderson's Avatar
 
Join Date: Nov 2003
Location: Castle Hills, TX
Posts: 102
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by spaceworm View Post
The Trainer 40 was originally the RCM Trainer (see picture attached) it was marketed by Bridi and called the RCM Bridi Trainer. Bridi also marketed a kit of an enlarged version, called the Trainer 60 (which I had), Kraft also had a version of the 40 called the Krafty. GP picked up the rights and marketed theirs. There is a wealth of info on the RCU Forums. Just use RCM Trainer, or Bridi Trainer 40, and you will bring up the history. I think they are all basically the same plane, except the first versions had a rubber banded wing and later it was bolt on. Other subtle changes for manufacturability were made I am sure. It was a great design that would still be so today. There are good plans on one of the RCU sites. Enjoy yours.

Sincerely, Richard
Thanks for the info, Richard - I'll certainly look it up as I could certainly use as much info as possible during my re-introduction to Flying RC Airplanes. I agree, it is a great design! I recently requested its reintroduction on the Great Planes website as they have a 'What plane would you like to see ...' question. Not sure why they ever discontinued it, it seemed like a logical next step from a basic trainer. I did skip a step, and flew that one as my basic trainer with some help from other flyers. They didn't mind flying it as it certainly didn't fly like the standard flat bottom wing trainer. I'll take pictures of my building adventure, who knows . . . we might convince GP to release it again - hahah!

Thanks again for the info!

Mark
Old 02-13-2017, 09:43 AM
  #9  
Bax
My Feedback: (11)
 
Join Date: Apr 2002
Location: Monticello, IL
Posts: 19,483
Likes: 0
Received 5 Likes on 5 Posts
Default

Originally Posted by spaceworm View Post
The Trainer 40 was originally the RCM Trainer (see picture attached) it was marketed by Bridi and called the RCM Bridi Trainer. Bridi also marketed a kit of an enlarged version, called the Trainer 60 (which I had), Kraft also had a version of the 40 called the Krafty. GP picked up the rights and marketed theirs. There is a wealth of info on the RCU Forums. Just use RCM Trainer, or Bridi Trainer 40, and you will bring up the history. I think they are all basically the same plane, except the first versions had a rubber banded wing and later it was bolt on. Other subtle changes for manufacturability were made I am sure. It was a great design that would still be so today. There are good plans on one of the RCU sites. Enjoy yours.

Sincerely, Richard
The Great Planes Trainer 40 IS the Bridi RCM Trainer 40. Don Anderson, who founded Great Planes actually bought Bridi Hobby Enterprises. The RCM Trainer 60 was actually the first one designed by Joe Bridi, and was just called the "RCM Trainer". The .40 and .20 size versions came out afterward.
Old 02-14-2017, 08:32 AM
  #10  
spaceworm
 
Join Date: Mar 2009
Location: Guilford, CT
Posts: 3,950
Received 2 Likes on 2 Posts
Default

Originally Posted by Bax View Post
The Great Planes Trainer 40 IS the Bridi RCM Trainer 40. Don Anderson, who founded Great Planes actually bought Bridi Hobby Enterprises. The RCM Trainer 60 was actually the first one designed by Joe Bridi, and was just called the "RCM Trainer". The .40 and .20 size versions came out afterward.
FWIW and to get further off of the Tiger thread, search online for "RCM TRAINER" and also search RCU files for the same. More detail and confusion for the original RCM TRAINER and it's variations. Outerzone has free download of the original RCM TRAINER, which see. Enjoy.
Old 02-16-2017, 01:21 PM
  #11  
markfsanderson
 
markfsanderson's Avatar
 
Join Date: Nov 2003
Location: Castle Hills, TX
Posts: 102
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by spaceworm View Post
FWIW and to get further off of the Tiger thread, search online for "RCM TRAINER" and also search RCU files for the same. More detail and confusion for the original RCM TRAINER and it's variations. Outerzone has free download of the original RCM TRAINER, which see. Enjoy.
Sorry, yeah it seems like I kind of hijacked the thread! But thanks for insight! I found a moderately discounted GP wing jig on EBay which I'll be using to build with. I'm not sure if I'm going to use wood glue or CA . . . we'll see!

Mark!

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

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.