Hi Mark, Thanks for taking the time to reply with your feedback, much appreciated. You've answered a few questions I've been pondering about and probably should look out for a suitable flat leaf spring or ideally one with a 20° bend to match an Aviation Products tailwheel assembly rather than seeing if I could get an aluminium or fibreglass spring to work.
Brad ________________________________________ From: KRnet [krnet-boun...@list.krnet.org] on behalf of Mark Langford via KRnet [krnet@list.krnet.org] Sent: 10 February 2019 19:41 To: krnet@list.krnet.org Cc: Mark Langford Subject: Re: KR> Tail Wheel Springs (but aluminium) Brad wrote: > Since tailwheel springs are in discussion at the moment, has anyone made a tailwheel spring out if aluminium bar and if so - > 1. What spec was used? > 2. Could it be formed e.g. 20° and if so, must it be formed before any type if straightening treatment(if relevant)? > 3. I assume it could be drilled, cut once formed? > 4. Any ideas what length, thickness for a 900lb KR-2 is advisable? I made a spring a few years ago, using a 2" wide x 3/8" thick piece of 2024 (or maybe it was 7075) which is pretty stiff compared to 6061. Although it's only about 15" long, it sagged too much to support the tail with the pilot seated. So I used it as a form for a carbon fiber one that's maybe 7/16" thick, and it was also too floppy. So I stuck the two together (out of expediency) and it worked pretty well, but didn't take long to delaminate between the two. It still works OK, but I need to wrap it with some BID to hold it together....one of the many things on my list that I need to do. I can tell you that it was almost beyond my physical capability to bend the aluminum (using bar clamps, hangar beam, and a long extension bar), but with a press brake, it's certainly doable. I also use the Aviation Products tailwheel, which requires a leaf spring to bolt to it. More on that is at http://www.n56ml.com/kgear.html, if you haven't seen it. Really, there's no substitute for a steel leaf spring, which is what I have on the KR2S. It's just a lot heavier than carbon fiber or aluminum, if aft CG is already a concern. I've also seen a lot of early KRs with a short little (and much thinner) steel spring that almost looks like a "tab" hanging 3 or 4 inches aft of the tail spring block. Not much spring to it, but apparently it works enough to remain in place for decades on these old planes, and dirt simple, and very light. One downside is you lose tailwheel authority due to the much shorter moment arm to the main gear. Hope this helps.... Mark Langford m...@n56ml.com http://www.n56ml.com _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
