J3 Tail Springs

[Doug123 26]

Here is SN: Model C sn: 573 with new J3 tail springs! 

[wypaul 448]

I’m wonderIng if the flat ground angle is going to increase your takeoff roll and landing speed.  If it were me I would shorten that spring but I fly into a lot of short strips. Nice battery rail.

I hope you have those health issues behind you and blue skies ahead!

[Doug123 26]

Thanks for the input, I was in the same line of thinking.  So glad I wasn’t the only one thinking of that.  I have a spare spring and thought about cutting the installed one, and taking an inch off and see what kind of difference it makes.  I wanted a bit more height for dirt strips. 
 

My medical issues maybe resolved post surgery next month, but I have a friend who’s also has lots of tail wheel time to fly with me.  She’s a  CFI too..

[nlappos 413]

My thoughts:

I suspect the best short field takeoff depends on the softness of the surface. If the field is not very soft, and therefore the wheel drag is low, then raising the tail early in the takeoff run might lead to better acceleration and shorter ground run. Also, the snap liftoff when you finally raise the nose will make you climb earlier than mushing off with max angle of attack held throughout the ground run.

If the surface is soft, then getting the weight off the wheels earlier is probably best, so a max angle of attack ground run is best.

In either case, the shorter tail spring is a better bet, because you get the choice of having a high angle of attack on the ground run. A long spring takes away that choice.

[Dusty 126]

Just a suggestion before the tail end is covered. Put the lift handle to the top longeron it will make handling easier

 

[Doug123 26]

I may leave the handle as I am a short dude, and have found the handle for my T-Rex arms leaves me with good lifting leverage.  

I too like the idea of a slightly shorter spring.  I’ll let you know the results.  

DC Flyer on YouTube has wider cabain style gear.  Who makes that style, as I am looking into replacing the shock cords style gear and go wider, but not much taller..

[SuberAvid 617]

Doug, when I was running a standard tail spring I cut off an inch or maybe 1.5 inches ( I can't remember exactly) , and also had to cut the backer spring and also tapered it to soften it as it gets closer to the TW.  Shortening it will definately help your angle of attack which will help to shorten your takeoffs and landings.

[Doug123 26]

Thanks for the information.   The original tailwheel spring when I bought the plane was 1.5”s wide, very short and poorly narrowed.  The trail/caster was not correct.  Only one side of the spring was cut to fit the in the tail bracket and tailwheel.  It would only turn to the right, but there was little to none control left.  She was ground looped a few times by the previous owner and once by me. (No damage) 

The new 1.250 width J3 spring from Univair made all the difference.  We’ve taxi tested low and high speeds and now we have positive control left and right as a proper tailwheeler.  I’ll shorten the spring today, and then finish the skin.  

Thank for the advice. Pictures to follow.

[Buckchop 479]

Randy Moore in Tenn built my gear fo my model 1, talkin to him now about makin a set for my new to me model 5, i had him lift the firewall up 4” and took the backin plates out to 73” (have to check to b sure but think thats right.) was $1200 for the whole setup with cabane and struts. 

[Doug123 26]

Thanks, I’ll get in touch with him.  Attached are pictures of the original spring.  Notice the offset holes. 
 

The J3 tailwheel spring attach hole is moved up 1” which lowers the tail.