Welcome to the WIMAC forums.

You are currently viewing our site as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact us.

Go Back   WIMAC > R/C > Projects and Builds

Projects and Builds Share your project builds, tips and tricks.

Reply
 
Thread Tools Display Modes
  #21  
Old 1 Week Ago
briankizner briankizner is offline
Past President
First Name: Brian
Last Name: Kizner
MAAC Number: 36125
WIMAC WINGS: Instructor
 
Join Date: Jan 2007
Posts: 744
briankizner is on a distinguished road
Same here. I built and flew a Sportster as well. It was good but I definitely preferred the Tiger. As Kevin said, more precise.
Reply With Quote
  #22  
Old 5 Days Ago
Ian's Avatar
Ian Ian is offline
Club Member
First Name: Ian
Last Name: San Agustin
MAAC Number: 96252
WIMAC WINGS: Solo Planes
 
Join Date: Jul 2019
Posts: 35
Ian is on a distinguished road
Update 10-Nov: Keep calm and measure twice!

Yup, this build is getting interesting!

The fuselage is now dry framed-up (not all glued yet). Crazy that it took the whole weekend only to get this far! My first major surprise: the bulkheads do not interlock squared and straight like the fuselage of the Goldberg Eagle I built last winter.... AND with the exception of the firewall bulkhead, the rest of the bulkheads are just 1/8" aircraft plywood and nothing else; no doublers or balsa side braces. This makes for flimsy and easy to break bulkheads. Second surprise: although the fuselage sides were packed at the bottom of the box, somehow they were bowed possibly from years of staying at-rest in the box. Consequent to this, it is very easy to get the fuselage out of alignment. So, for the next week, I will keep the clamp braces on the fuselage as you see on the photos to allow the wood to re-bend and resolve the situation. Next weekend, I'll go back to epoxy bonding the bulkheads fuselage top & bottom panels permanently.

Modifications made: I spent the weekend basically cutting and adding doublers, balsa traingle stocks and where necessary, added braces to the cabin bulkheads. Also, for those of you who built Goldberg Tigers before, you may (or may not?) have noticed that the side guards or cheeks of the engine had a tendency to vibrate or flutter. You'll see on one of the photos that I also added basswood lateral doublers to the side guards, that will hopefully prevent that vibration.

Lesson learned in building: You can build airplanes fast, but it may not look nor fly straight. Time, patience and a good cup of coffee (or tea) are important building tools. Also: balsa triangle stocks are amazing... they are like the duct tape for model building

Have a great week ahead folks... Cheers for now!
Attached Thumbnails
pic8.jpg   pic9.jpg   pic10.jpg  

pic11.jpg   pic12.jpg  
Reply With Quote
  #23  
Old 5 Days Ago
briankizner briankizner is offline
Past President
First Name: Brian
Last Name: Kizner
MAAC Number: 36125
WIMAC WINGS: Instructor
 
Join Date: Jan 2007
Posts: 744
briankizner is on a distinguished road
Very normal that a trainer like the Eagle would be built heavier than a higher performance aircraft. Trainers have a lot of lift and are built to handle some abuse so they do not suffer too much from extra weight. They also were designed with considerations for inexperienced builders, hence the foolproof interlocking parts. Intermediate planes built for more aerobatic flight need to be light to perform and will sacrifice some strength for lighter weight. Ie, built to fly, not to crash. It also helps to keep the posterior part of the fuselage light so that it should not require added weight up front to establish a correct center of gravity. Added triangles and doublers will be great for stiffness, but be careful not to add much weight. Higher performing airframes, especially ones designed for electric power, tend to be quite flimsy (1-not much concern for damage caused by the engine’s vibration but a lot of concern about the weight of the batteries 2- I realize the Tiger is designed for glow engines and so is fairly solid, though perhaps less solid than a trainer)
I never experienced or heard of vibration problems of the sides around the engine. Maybe because I used a fair bit of epoxy on them for fuel proofing.
Personally, I found the Tiger to be very well designed to be a great everyday flyer without any important changes. That being said, I know that many builders Enjoy modifying kits to their liking. More power to them. The great thing about kit building compared to ARFs is that no two are identical. The only other plane that I have had that was it’s equal in that it was as easy as a trainer and a lot of fun to fly aerobatics with was the Sig Kavalier. However, I found Goldberg kits were easier and more fun to build than Sig. I’d go farther and say that They were the best builds of any of the kit manufacturers that I had experience with ( Including Graupner, Sig, Midwest., Balsa USA, possibly others that I have forgotten. I’m not counting Assembly of ARFs here, only boxes of wood and hardware with plans and instructions).
Good idea to keep it clamped for a while to keep it straight. I think you’re right that the wood may have warped after years in the box. One tip I learned a long time ago for warped wood was to wet the wood before bending it back to normal. After drying, it should remain straight. I’m sure you’ll build a real beauty. Great start!
Reply With Quote
  #24  
Old 5 Days Ago
Ian's Avatar
Ian Ian is offline
Club Member
First Name: Ian
Last Name: San Agustin
MAAC Number: 96252
WIMAC WINGS: Solo Planes
 
Join Date: Jul 2019
Posts: 35
Ian is on a distinguished road
Quote:
Originally Posted by briankizner View Post
Very normal that a trainer like the Eagle would be built heavier than a higher performance aircraft. Trainers have a lot of lift and are built to handle some abuse so they do not suffer too much from extra weight. They also were designed with considerations for inexperienced builders, hence the foolproof interlocking parts. Intermediate planes built for more aerobatic flight need to be light to perform and will sacrifice some strength for lighter weight. Ie, built to fly, not to crash. It also helps to keep the posterior part of the fuselage light so that it should not require added weight up front to establish a correct center of gravity. Added triangles and doublers will be great for stiffness, but be careful not to add much weight. Higher performing airframes, especially ones designed for electric power, tend to be quite flimsy (1-not much concern for damage caused by the engine’s vibration but a lot of concern about the weight of the batteries 2- I realize the Tiger is designed for glow engines and so is fairly solid, though perhaps less solid than a trainer)
I never experienced or heard of vibration problems of the sides around the engine. Maybe because I used a fair bit of epoxy on them for fuel proofing.
Personally, I found the Tiger to be very well designed to be a great everyday flyer without any important changes. That being said, I know that many builders Enjoy modifying kits to their liking. More power to them. The great thing about kit building compared to ARFs is that no two are identical. The only other plane that I have had that was it’s equal in that it was as easy as a trainer and a lot of fun to fly aerobatics with was the Sig Kavalier. However, I found Goldberg kits were easier and more fun to build than Sig. I’d go farther and say that They were the best builds of any of the kit manufacturers that I had experience with ( Including Graupner, Sig, Midwest., Balsa USA, possibly others that I have forgotten. I’m not counting Assembly of ARFs here, only boxes of wood and hardware with plans and instructions).
Good idea to keep it clamped for a while to keep it straight. I think you’re right that the wood may have warped after years in the box. One tip I learned a long time ago for warped wood was to wet the wood before bending it back to normal. After drying, it should remain straight. I’m sure you’ll build a real beauty. Great start!
Very meaningful insight, thank you very much Brian!
That is true, in wood constructed airplanes, light can still be (relatively) stiff and durability can suffer weight gain. I am realizing now that I have to be more comfortable that the wood joints will keep the airframe sound. Point well taken on being careful not to go wild and crazy with triangle stocks.

Thank you for the reminder about wetting the wood to conform to curves. Yes, I will definitely do this next weekend. The planking on the front lower side requires a forward bend to the firewall so I will use this technique on that part and a few others.

I look forward to meeting you in on the field next season and show you this airplane when it's ready. Cheers!
Reply With Quote
  #25  
Old 5 Days Ago
briankizner briankizner is offline
Past President
First Name: Brian
Last Name: Kizner
MAAC Number: 36125
WIMAC WINGS: Instructor
 
Join Date: Jan 2007
Posts: 744
briankizner is on a distinguished road
Re: wetting wood to bend it. The one Balsa USA kit ( Taube, a truly unique World War 1 monoplane) I built had complex wingtips fashioned by bending several thin strips of balsa to the correct curvature, gluing them together, than sanding everything to a smooth curve. This absolutely required wetting the wood before bending to prevent it from being cracked. It was a lot of work and very dusty, especially all the sanding, to make wingtips this way but the result was very nice.
Reply With Quote
Reply

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
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

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
A new build: a 10-300 Carl Goldberg Stephy General Discussion 17 2013-02-04 08:12 PM
Tiger 2 landing gear stephane.savard General Discussion 2 2008-07-06 05:24 PM


All times are GMT -4. The time now is 06:10 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.