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Ok so I have been doing some major repairs and overhauls of a number of rockets a friend gave me. I noticed that the launch lugs where 2-4 long depending, and only one.
I have been using 2 launch lugs with angled cuts. Only ¼ ½ long with great success. Ever since I can remember and have never had any issues but have seemed to gain performance. So I decided I would ask you all what you think. I also like to use standoffs on some modles to protect the paintjob
Exactly my feelings, too. I have to say that I have never really thought much about it. Maybe I should give it some consideration, but I haven't yet. My only two concerns so far have been insuring that the lug doesn't bind on the rod and insuring that the rod clears everything on the rocket. I'm not a real altitude freak anyway; I have enough trouble keeping my rockets from going out of sight as it is, and keeping them within my 2 acre launch field when they come back down.I don't bother with streamlining the lugs in most cases, as I don't build for performance; it just doesn't matter to me.
I can put a rocket higher than I want to already. No need to add a few feet to the altitude.
I usually just try to camouflage them with paint, but you make a good point. I'm not as concerned about the aero issues, but the overall appearance? Now that's another matter entirely. :eyepop:... turns something that HAS to be there (excepting alternatives for sake of discussion) into something that looks like it could belong on the side of the rocket.
IMHO of course...
Later! OL JR
I was thinking more of using small wire screw eyes that would be screwed right into centering rings, in the same way that rail buttons are installed. I'm not that interested in the actual details of installation; I'm sure that a way can be devised to mount them securely without too much trouble. I'm more interested in finding out if anyone has ever tried using either screw eyes or some other type of ring lugs in something other than an egg lofter.
MarkII
Thanks for your reply, John. This is turning into a very interesting thread; it is something more than just a poll now. (Kudos, Charlaine.) I like the idea of incorporating scale versions of the lugs on, say, sounding rockets like the Black Brant II or the Nike Smoke for instance, and have the scale lugs actually be functional. The problem is setting up a launch pad (finding a rail) that would work with the scale lugs. You would almost have to construct a scale model of the real launch pad, too, which would be adding another project on top of building the model, and it would only work with that one model. Scale plans for the BBII pads at Churchill or Wallops or the Sandhawk pad at Barking Sands aren't exactly easy to find (wish they were!), and then there is the problem of fabricating a rail if the model is too small for the existing sizes of T-slot extrusion (80:20 rail).
Regarding ring lugs, the reason that I brought them up was because I had seen plans for competition egg lofters that used them (hand made from thin wire), and I wondered why they weren't used more often, such as on sport rockets. A recent review on EMRR of Sheri's Mercury-Atlas MPR/HPR scale rocket mentioned that she uses screw eyes for launch lugs in her kit, which sounds pretty cool, but that is the only other mention of ring lugs that I have found so far. On sport models, their appearance as scale components wouldn't be an issue; I'm interested in them as a less noticeable alternative to the conventional tubular launch lug. I think that in an earlier post you mentioned something about using fishing rod eyes as lugs, which I find fascinating. Have you actually ever used them on a rocket?
On a fantasy/sci-fi model, using ring lugs disguised as antennae (which you have also mentioned) is also an intriguing idea.
MarkII
Another question: how important do people feel it is to have the inner diameter of the launch lug closely match the diameter of the launch rod? Does it really matter if there is some "play" in the fit, even a pretty good amount of "play?" Recently I launched my FSI Hercules clone at a club launch. The Hercules is 33.75" tall, has an OD of 2.34", and it weighed (with a dummy payload and 3 D12-5's in the cluster motor mount) about 770 grams, or 27.16 oz. at the time of launch. My version has 3/8" lugs (13/32" thin-wall brass tubing), but the largest rod that my club had at the range was a 4' x 3/16" rod, so that was what I launched it from. Obviously, there was considerable play in the fit of the lugs over the rod, and the thin rod might have even swayed a little bit with my rocket resting against it, yet the Hercules launched perfectly straight and true, without the slightest hint of rod whip.
I suspect that you would not want to get TOO extreme with using an oversized lug (or an undersized rod), but I am wondering if anyone else has had similar experiences with using lugs that were clearly oversized for the launch rod that you were using. If you did so, did you encounter any problems with them? Since the poll is about the various ways that modelers implement launch lugs on their rockets, this question fits right in with the thread.
MarkII
Yes, I agree. Using the 3/16" rod was certainly not a desired situation, but I went with it because that was all that was available at the launch. My club does have 1/4" rods (and pads that use them) as well as a launch rail, but they are rarely brought to launches because they are so infrequently used. (The rail was brought to a few launches during the first year that the club had it, several years ago, but it has not made any appearances since then.) Of course they will never get used if they stay in the storeroom, but that's not my call. I could bring my own rods and my rail, but members are asked not to bring any of their own equipment to club launches.Its been my experience a little play isn't a bad thing but excessive play and I'd say a 3/8" Lug on a 3/16" rod may be getting close to what I'd deem excessive depending on the wall thickness of the lug
Its been my experience a little play isn't a bad thing but excessive play and I'd say a 3/8" Lug on a 3/16" rod may be getting close to what I'd deem excessive depending on the wall thickness of the lug
The purpose for Launch Lugs of whatever configurationis to keep the vehicle moving SMOOTHLY along the guide with a minimum amount of contact friction. the larger the lug the more movement and friction is encountered. Over sized lugs can cause the rod whip you are expecting from to tight a lug as it depends on where the model happens to be riding on the rod at the time it leave the rod. One launch can be perfectly fine while the same model/motor combination can tip off sideway on the very next flight.
General rule of thumb has been At least for models in the 1/8A to G range one size up over the rod size is fine, anything larger can produce undesired results.
Personally I prefer whatever launch lug arrangement i'm using to be pretty close to the size of the rod, rail of beam I'm riding. I like keeping things going it the direction it's pointed. This is particularly true with clustered models as there are many more way for the varience in thrust of the motors, wind gusts, and other factors to alter the way the model travel the rod or rail.
I have seen 1/2"x 1-1/2" lugs torn from the side of a fairly heavy F powered model flying from a 1/4" x 6foot rod. Looked to me like the model was attempting to turn away for the thrust line as it jammed the forward lug on the rod. Model ended up land sharking all over the field. Was this "caused" by the oversize lugs or a malfuncting motor? I'm not sure, but the end result was a failed and somewhat dangerous launch that shouldn't have been.
Another question: how important do people feel it is to have the inner diameter of the launch lug closely match the diameter of the launch rod? Does it really matter if there is some "play" in the fit, even a pretty good amount of "play?" Recently I launched my FSI Hercules clone at a club launch. The Hercules is 33.75" tall, has an OD of 2.34", and it weighed (with a dummy payload and 3 D12-5's in the cluster motor mount) about 770 grams, or 27.16 oz. at the time of launch. My version has 3/8" lugs (13/32" thin-wall brass tubing), but the largest rod that my club had at the range was a 4' x 3/16" rod, so that was what I launched it from. Obviously, there was considerable play in the fit of the lugs over the rod, and the thin rod might have even swayed a little bit with my rocket resting against it, yet the Hercules launched perfectly straight and true, without the slightest hint of rod whip.
I suspect that you would not want to get TOO extreme with using an oversized lug (or an undersized rod), but I am wondering if anyone else has had similar experiences with using lugs that were clearly oversized for the launch rod that you were using. If you did so, did you encounter any problems with them? Since the poll is about the various ways that modelers implement launch lugs on their rockets, this question fits right in with the thread.
MarkII