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1981 Cobra trailer gas struts



 
 
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  #31  
Old March 19th 20, 12:17 AM posted to rec.aviation.soaring
David Cleveland
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Default 1981 Cobra trailer gas struts

Wings and Wheels has the struts for the trailers that are inside. The struts for the single seat measure 45"- 46". Call W/W and they will help once you measure yours. Look to see if there are any markings that indicate the strut force. There are several versions.

Don't wait. Besides not being able to lift the clamshell top to get your glider out as the CUs are popping, the reasons are obvious.


DC
  #32  
Old March 19th 20, 03:47 AM posted to rec.aviation.soaring
[email protected]
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Default 1981 Cobra trailer gas struts

Charlie- do you have a neurological problem with your right hand? Your posts indicate a possible case of uncontrollability with your third finger. The "ROL." finger, as it is referred to in typing, seems to jitter on the "period" key, resulting in a shortage of periods available to the rest of the world.
  #33  
Old March 19th 20, 04:12 PM posted to rec.aviation.soaring
Dennis Cavagnaro
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Default 1981 Cobra trailer gas struts

Just to accent your point Dave when i bought my Ventus it had a new canopy ...apparently the strut failed on the trailer when the glider was roll out on the ramp and the handle was in the Verticle (open), position when it collapsed.

DC (the other DC)
  #34  
Old March 19th 20, 08:41 PM posted to rec.aviation.soaring
Charlie M. (UH & 002 owner/pilot)
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Default 1981 Cobra trailer gas struts

No more issue than "non flying types" asking why I fly an aircraft with no engine...."extra dots" may be similar to a pause while face to face....dots can signify a breath while face to face....

I deleted previous post since limited value to this thread...just answering you....

Previous post had some limited value here.....BTDT.....
  #35  
Old June 18th 20, 12:53 PM posted to rec.aviation.soaring
David Cleveland
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Default 1981 Cobra trailer gas struts

I finally was able to get some custom gas springs made and installed. They work very well. The short story is that I used a company in Oregon, American Gas Springs. I know others have had good results getting custom springs made by other sources, but I wasn't able to find any who would make small orders.

I used 1200N for a final gas spring force. A detailed description of the process, as well as the dimensions and install are described in a document available on Google Drive:

https://drive.google.com/file/d/1oEe...ew?usp=sharing

  #36  
Old June 18th 20, 10:46 PM posted to rec.aviation.soaring
Richard Pfiffner[_2_]
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Posts: 319
Default 1981 Cobra trailer gas struts

On Thursday, June 18, 2020 at 4:53:33 AM UTC-7, David Cleveland wrote:
I finally was able to get some custom gas springs made and installed. They work very well. The short story is that I used a company in Oregon, American Gas Springs. I know others have had good results getting custom springs made by other sources, but I wasn't able to find any who would make small orders.

I used 1200N for a final gas spring force. A detailed description of the process, as well as the dimensions and install are described in a document available on Google Drive:

https://drive.google.com/file/d/1oEe...ew?usp=sharing


I used the same company American Gas Springs but I used 1300N. Easier to life and almost goes up by itself. Pull some to get down.

I picked mine up only 40 miles north of me. They have an extensive product line of gas springs etc. for everything and a really nice manufacturing facility.

Richard
www.craggyaero.com

  #37  
Old June 19th 20, 03:46 PM posted to rec.aviation.soaring
[email protected]
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Default 1981 Cobra trailer gas struts

Nice work. I had to do that for an older (1978) Komet many years ago and, like you, was shocked at just how heavy the top is.

Two thoughts:

1. It should be obvious but rod-end-down/body-end-up can be different in the raised and lowered positions. I've seen trailers that way and the LS-3 landing gear is also, forcing you to pick one alternative. I go for the position that the mechanism is in 99% of the time (i.e., top down for a trailer)..

2. The attach bolts are cantilevered out beyond the trailer wall and have been known to fail. I suspect that's more likely if you insert a lot of washers as spacers. Just be careful to monitor that. They apparently bend before they fail so you should see it. I don't know what was there originally but consider sourcing some Grade 8 or other very-high-strength bolts. Maybe even drilling out the holes oversize and going up in size.

Perhaps someone else can comment on bolt failures. It's a known, apparently not-very-common, but potentially disastrous weakness.

It's a greatÂ*feeling to get everything installed and working--even though all you have is what you started out with.

Chip Bearden
JB
  #38  
Old June 20th 20, 02:22 AM posted to rec.aviation.soaring
Frank Whiteley
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Posts: 2,099
Default 1981 Cobra trailer gas struts

On Friday, June 19, 2020 at 8:46:04 AM UTC-6, wrote:
Nice work. I had to do that for an older (1978) Komet many years ago and, like you, was shocked at just how heavy the top is.

Two thoughts:

1. It should be obvious but rod-end-down/body-end-up can be different in the raised and lowered positions. I've seen trailers that way and the LS-3 landing gear is also, forcing you to pick one alternative. I go for the position that the mechanism is in 99% of the time (i.e., top down for a trailer).

2. The attach bolts are cantilevered out beyond the trailer wall and have been known to fail. I suspect that's more likely if you insert a lot of washers as spacers. Just be careful to monitor that. They apparently bend before they fail so you should see it. I don't know what was there originally but consider sourcing some Grade 8 or other very-high-strength bolts. Maybe even drilling out the holes oversize and going up in size.

Perhaps someone else can comment on bolt failures. It's a known, apparently not-very-common, but potentially disastrous weakness.

It's a greatÂ*feeling to get everything installed and working--even though all you have is what you started out with.

Chip Bearden
JB


I seem to recall that the Komet trailers originally came with 8mm bolts and that because of the failures it was recommended to replace them with 10mm bolts.

Frank Whiteley

  #39  
Old June 20th 20, 12:59 PM posted to rec.aviation.soaring
David Cleveland
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Posts: 28
Default 1981 Cobra trailer gas struts

Referencing Chips comment about using harder bots. He is absolutely correct.. Many trailers I've seen, mine included, have multiple washers at the mounting point to move the strut and spring arms out away from the trailer. Use caution.

Metric bolts have a different hardness grading system. A metric bolt marked 8.8 is the same hardness as an SAE grade 5. If you want to upgrade the hardness of a metric bolt, use a 10.9 or even 12.9. Frank's comment about using a large diameter bolt would be a good idea as well.
  #40  
Old June 20th 20, 05:02 PM posted to rec.aviation.soaring
Richard Pfiffner[_2_]
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Posts: 319
Default 1981 Cobra trailer gas struts

On Saturday, June 20, 2020 at 4:59:06 AM UTC-7, David Cleveland wrote:
Referencing Chips comment about using harder bots. He is absolutely correct. Many trailers I've seen, mine included, have multiple washers at the mounting point to move the strut and spring arms out away from the trailer. Use caution.

Metric bolts have a different hardness grading system. A metric bolt marked 8.8 is the same hardness as an SAE grade 5. If you want to upgrade the hardness of a metric bolt, use a 10.9 or even 12.9. Frank's comment about using a large diameter bolt would be a good idea as well.


If you can't find metric you could use 5/16" grade 8 bolts these are only .0015" smaller than an 8mm basically the same.
McMaster Carr has a selection of grade 8 both the carriage bolt that is used on the bottom end and the hex head used on the upper. Also use the nyloc nuts. Highest grade they offer on the carriage is 8, 10 offered for the upper bolts.

They have the both metric bolts in the 8.8 or Grade 5.

Richard
www.craggyaero.com
 




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