Page 5 of 5 FirstFirst 12345
Results 61 to 64 of 64

Thread: Huge R/C Jet Structural Failure

  1. #61
    Registered User
    Join Date
    Jan 2013
    Location
    USA.
    Posts
    4,206
    Likes (Given)
    2008
    Likes (Received)
    3479

    Re: Huge R/C Jet Structural Failure

    Back in the early 70's I got tired of contest flying in Open Pylon and Fun Fly events and thought I would try contest Pattern flying. I always designed all of my model since I was about 10 years old. Designed and built a F-86 Pattern airplane, 72" wing span with the swept wings and inverted engine with the spinner at the radar dome. Flew very good, but after practicing a couple months, I just don't like having to fly the exact flight each time, I got bored, I like more of free style flying. One day I was taking the F-86 up very high and was diving it straight down with WOT on the Super Tiger engine running lots of nitro and pulling out inverted and going down the runway about 5' inverted and then back up and about the 4th time by flying buddy told me that I was going to pull the wings off. I laughed. The next time I started to pull out of the vertical dive inverted when the wing failed at the center section and each wing panel went back and crushed the rear of the fuselage. Had to dig the engine out of the ground. I hot wired the wing panels and was covered with 1/16" balsa with spruce spar caps in the foam. At the center section the spruce spar caps had 1/4" aircraft plywood on each side of the spruce spar caps out about 8" on each wing panel and the center section of the wing was fiber glassed 16" wide in the center. The wing failed in the center.
    That was the last of the TLAR aircraft design.
    I was going to build another F-86 with retract gear and that was before anyone had retract gear on their models, so I built my own along with a retract servo for the extra strength needed. Ended up doing some engineering work for Carl Goldberg in designing his first retract gear that he put on the market. The servo was also put on the market by another company, (Long story).
    I have about 24 RC aircraft designs.
    Pops

  2. Likes rv6ejguy liked this post
  3. #62
    Registered User larr's Avatar
    Join Date
    Apr 2012
    Location
    markham, ontario, canada
    Posts
    112
    Likes (Given)
    0
    Likes (Received)
    23

    Re: Huge R/C Jet Structural Failure

    Just found a basic construction photo. Shocker it is all plywood formers and looks like yards of balsa sheet. I stand completely corrected. Never seen anyone do that for 30 years on a large model. That would never survive.
    How soon they forget.
    Click image for larger version. 

Name:	ImageD_The_first_RAF_Vampire_F.jpg 
Views:	36 
Size:	32.0 KB 
ID:	57958Click image for larger version. 

Name:	0675278.jpg 
Views:	37 
Size:	88.9 KB 
ID:	57959Click image for larger version. 

Name:	111-0372-F30-fuse-assy-sml.jpg 
Views:	34 
Size:	82.4 KB 
ID:	57960
    Click image for larger version. 

Name:	ImageH_A_Vampire_T.jpg 
Views:	39 
Size:	78.5 KB 
ID:	57961

    The DeHavilland Vampire was the RAF's first jet fighter and was largely of wood construction - balsa and plywood, BTW.

    As to the failure mode of the model, the servos can generate tremendous forces that would be enough to destroy control surfaces and internal structures.

  4. Likes Himat, DangerZone liked this post
  5. #63
    Registered User
    Join Date
    Jan 2013
    Location
    USA.
    Posts
    4,206
    Likes (Given)
    2008
    Likes (Received)
    3479

    Re: Huge R/C Jet Structural Failure

    Quote Originally Posted by larr View Post
    How soon they forget.
    Click image for larger version. 

Name:	ImageD_The_first_RAF_Vampire_F.jpg 
Views:	36 
Size:	32.0 KB 
ID:	57958Click image for larger version. 

Name:	0675278.jpg 
Views:	37 
Size:	88.9 KB 
ID:	57959Click image for larger version. 

Name:	111-0372-F30-fuse-assy-sml.jpg 
Views:	34 
Size:	82.4 KB 
ID:	57960
    Click image for larger version. 

Name:	ImageH_A_Vampire_T.jpg 
Views:	39 
Size:	78.5 KB 
ID:	57961

    The DeHavilland Vampire was the RAF's first jet fighter and was largely of wood construction - balsa and plywood, BTW.

    As to the failure mode of the model, the servos can generate tremendous forces that would be enough to destroy control surfaces and internal structures.
    Correct. Before metal gears in servos, I was constantly stripping gears in servos in my contest Fun Fly design. I went to aerodynamically balance control surface including the ailerons. When doing better that 60 +rolls in 30 seconds the loads are very high. After than, wings started to fail and then I had to address that. Usually built 5 or 6 at a time. A model with 48" of wing span, slightly under 3 lbs with a very large control surfaces and a racing Super Tiger .60 engine running on about 40% nitro, airplanes don't last very long. Could hold straight up and let go and it would accelerate going straight up and go out of sight in about 9-10 seconds. Lots of fun holding the tail of the tiger.
    Pops

  6. #64
    Registered User DangerZone's Avatar
    Join Date
    Sep 2011
    Location
    Zagreb HR
    Posts
    1,918
    Likes (Given)
    1006
    Likes (Received)
    322

    Re: Huge R/C Jet Structural Failure

    Quote Originally Posted by larr View Post
    How soon they forget.
    Click image for larger version. 

Name:	ImageD_The_first_RAF_Vampire_F.jpg 
Views:	36 
Size:	32.0 KB 
ID:	57958Click image for larger version. 

Name:	0675278.jpg 
Views:	37 
Size:	88.9 KB 
ID:	57959Click image for larger version. 

Name:	111-0372-F30-fuse-assy-sml.jpg 
Views:	34 
Size:	82.4 KB 
ID:	57960
    Click image for larger version. 

Name:	ImageH_A_Vampire_T.jpg 
Views:	39 
Size:	78.5 KB 
ID:	57961

    The DeHavilland Vampire was the RAF's first jet fighter and was largely of wood construction - balsa and plywood, BTW.

    As to the failure mode of the model, the servos can generate tremendous forces that would be enough to destroy control surfaces and internal structures.
    Excellent point about wood. On a side note, wasn't balsa used only as a core in the wooden plywood composite in the DeHavilland Vampire? The same way we use foam nowadays with synthetic materials like glass/carbon/aramid fibers to form a composite structure.

  7. Likes Battler Britton liked this post

Similar Threads

  1. HP in Ultralights? Why the huge difference?
    By Conundrum in forum General Experimental Aviation Questions
    Replies: 14
    Last Post: March 11th, 2015, 08:23 AM
  2. Sail-choppers. Helicopters with huge blade-spans like Sailplanes
    By Doggzilla in forum Aircraft Design / Aerodynamics / New Technology
    Replies: 18
    Last Post: September 1st, 2014, 03:47 PM
  3. Another electric plane. This one is huge!
    By Mac790 in forum Hangar Flying
    Replies: 32
    Last Post: May 17th, 2011, 03:50 PM
  4. huge airshow.
    By xj35s in forum Upcoming Events and Trip Reports
    Replies: 0
    Last Post: June 24th, 2009, 02:42 PM
  5. HUGE interest!
    By Captain_John in forum Hangar Flying
    Replies: 5
    Last Post: February 4th, 2007, 05:44 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •