Try SCIMITARS for serious 1/2A fun
#1
Thread Starter
Try SCIMITARS for serious 1/2A fun
I have posted several photos of 1/2A Scimitars in my Gallery for you to see. These little guys are fun, fast, and very aerobatic. Nothing tracks like a scimitar until you move a stick then it all happens. I powered one (Speedy) with a VA .049 RC and it was ballistic at 13oz and - for a 24 inch plane 120MPH is fast. My other 1/2A Scimitars have a 30-inch span and weigh in right at 16 oz. Originally powered by TEE DEE .051's they are pretty quick too though not Speedy fast I'm using throttled Norvels now. The one BabyScimitar. white/blue I designed and built back in the mid 80's and it's still flying. Short story: I took it off the building board and out to the field - it was powered by a TD.051 and had two standard servos at the time. I flew the tank dry twice and was absolutely thrilled with it's performance so I fueled it up again started the engine and launched it. I flew it for a couple of minutes then tested the vertical straight up til almost out of sight when it started back down on it's own rotating slowly - I had nothing - no elevator nothing and it went straight in . I was so eager to get it up in the air I neglected to charge my tiny 50mah battery and it died. There was very little damage to the plane but the engine was bent at the cylinder.
Last edited by gmeyers; 06-14-2017 at 06:09 PM.
#3
Thread Starter
#6
Thread Starter
You should try a micro with a TD .010 they can spin props up to 42,000 rpm.
https://www.youtube.com/watch?v=3i4r2kDOBlQ
https://www.youtube.com/watch?v=3i4r2kDOBlQ
Last edited by gmeyers; 06-15-2017 at 05:27 AM. Reason: add text
#7
I looked at your planes the other day the TD .010 was not posted at that time, did you fabricate
the RC carb yourself? Very nice, how does it perform any bench testing vids? I would recomend
the stock black prop / can unload to 42k, (if you don't use higher pitched modified props), the more
heavy grey robs rpm.
the RC carb yourself? Very nice, how does it perform any bench testing vids? I would recomend
the stock black prop / can unload to 42k, (if you don't use higher pitched modified props), the more
heavy grey robs rpm.
Last edited by Pond Skipper; 06-15-2017 at 06:21 AM.
#8
Thread Starter
I looked at your planes the other day the TD .010 was not posted at that time, did you fabricate
the RC carb yourself? Very nice, how does it perform any bench testing vids? I would recomend
the stock black prop / can unload to 42k, (if you don't use higher pitched modified props), the more
heavy grey robs rpm.
the RC carb yourself? Very nice, how does it perform any bench testing vids? I would recomend
the stock black prop / can unload to 42k, (if you don't use higher pitched modified props), the more
heavy grey robs rpm.
Actually I made the first carb about 1966 (i'm getting old) but the parts corroded mostly because I just put it in a box and didn't run fuel through it for the castor to get in and protect.
I have tried to make a TEE DEE .020 carb but no success. The .010 and .020 are complete different in personality , the .020 is not just a bigger .010.
Last edited by gmeyers; 06-15-2017 at 07:12 AM.
#11
My Feedback: (13)
Aloha gentlemen,
I built and have flown the 1/2 Simitar for years. I bought my from Bell Evans when he had a hobby shop in Simi Valley. I powered my with a TD.051 and though fast...not fast enough. I then installed a TD .09...and it was a good improvement...fast and I started to love this model. I waned more speed...so the next engine I installed was a TD.15 r/c engine...and I finally had the speed I was looking for. I flew this combination for years until I wore the engine out, I flew it that many times. I used 30% Cox glow racing fuel and it was so fast it just amazed me. I flew it in unlimited model races...and never took less then 2nd place, against some of the fastest nitro powered .40 class racing engines. It was so flipping fast it just shocked all that witnessed it fly and had a glide that never seem to end.
I need a good TD .15 to put it back into the air...does anyone have a good used one or new one they want to sell ?
Soft Landing Always,
Bobby
I built and have flown the 1/2 Simitar for years. I bought my from Bell Evans when he had a hobby shop in Simi Valley. I powered my with a TD.051 and though fast...not fast enough. I then installed a TD .09...and it was a good improvement...fast and I started to love this model. I waned more speed...so the next engine I installed was a TD.15 r/c engine...and I finally had the speed I was looking for. I flew this combination for years until I wore the engine out, I flew it that many times. I used 30% Cox glow racing fuel and it was so fast it just amazed me. I flew it in unlimited model races...and never took less then 2nd place, against some of the fastest nitro powered .40 class racing engines. It was so flipping fast it just shocked all that witnessed it fly and had a glide that never seem to end.
I need a good TD .15 to put it back into the air...does anyone have a good used one or new one they want to sell ?
Soft Landing Always,
Bobby
#12
Thread Starter
Aloha gentlemen,
I built and have flown the 1/2 Simitar for years. I bought my from Bell Evans when he had a hobby shop in Simi Valley. I powered my with a TD.051 and though fast...not fast enough. I then installed a TD .09...and it was a good improvement...fast and I started to love this model. I waned more speed...so the next engine I installed was a TD.15 r/c engine...and I finally had the speed I was looking for. I flew this combination for years until I wore the engine out, I flew it that many times. I used 30% Cox glow racing fuel and it was so fast it just amazed me. I flew it in unlimited model races...and never took less then 2nd place, against some of the fastest nitro powered .40 class racing engines. It was so flipping fast it just shocked all that witnessed it fly and had a glide that never seem to end.
I need a good TD .15 to put it back into the air...does anyone have a good used one or new one they want to sell ?
Soft Landing Always,
Bobby
I built and have flown the 1/2 Simitar for years. I bought my from Bell Evans when he had a hobby shop in Simi Valley. I powered my with a TD.051 and though fast...not fast enough. I then installed a TD .09...and it was a good improvement...fast and I started to love this model. I waned more speed...so the next engine I installed was a TD.15 r/c engine...and I finally had the speed I was looking for. I flew this combination for years until I wore the engine out, I flew it that many times. I used 30% Cox glow racing fuel and it was so fast it just amazed me. I flew it in unlimited model races...and never took less then 2nd place, against some of the fastest nitro powered .40 class racing engines. It was so flipping fast it just shocked all that witnessed it fly and had a glide that never seem to end.
I need a good TD .15 to put it back into the air...does anyone have a good used one or new one they want to sell ?
Soft Landing Always,
Bobby
#13
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TD .15's are rare these days and the only ones I have seen on EBAY were mint in box and awfully pricy. The Cox Conquest on the other hand is more frequently available and can be had a little cheaper. I liked my version, photo on my page, with a VA .049 the one named speedy was totally awesome speedwise though the blue and white scimitar with a Norvel .049 was the most fun to fly. If you want to burn the covering off the plane try a Nova Rossi .15 . Good luck.
TD's were always greedy on glowheads when pushed hard-and the use of TD heads on modified ST G15s before the Rossi came out also made huge inroads into the supply of spare heads.
ChrisM
'ffkiwi'
#14
Thread Starter
The Cox Conquest is way way bigger bulkier and heavier than a TD15-if you want something equivalent then something like an ASP 15 would be a far better match weight wise-and on that amount of nitro would outpull a TD 15. Another serious issue to consider with the TD.15 is the severe lack of heads-basically you'd be stuck with Medallion 15 heads-which rather defeat the purpose-or one of the Mecoa or similar adaptors which take a std 1/4-32 plug-which cost you rpm and power.. What you really want is someone to machine an original burnt out TD head to take a Nelson type plug=-and there are a few people out there who will do this....mine were done by Jon Fletcher in Australia-but I;m fairly sure Bob mattes still offers this service in the US.
TD's were always greedy on glowheads when pushed hard-and the use of TD heads on modified ST G15s before the Rossi came out also made huge inroads into the supply of spare heads.
ChrisM
'ffkiwi'
TD's were always greedy on glowheads when pushed hard-and the use of TD heads on modified ST G15s before the Rossi came out also made huge inroads into the supply of spare heads.
ChrisM
'ffkiwi'
I have used burned out plugs tapped and drilled for the TD .049, TD .09 but never for the TD .15. I tapped them for the standard glow plugs, the turbo plugs and the Nelson plugs - they performed very close to the originals with little increased performance which was the goal. I have plenty of head buttons for Norvel as well as the adapters so I shouldn't run out of them. I have no burned out TD .15 glowheads to adapt to the Nelson threads so won't experiment with them. They are hard to come by.
#15
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I Got out my handy digital postage scale and was surprised at the difference in weight between the TD .15 and the Conquest .15 . The TD is surprisingly light.
I have used burned out plugs tapped and drilled for the TD .049, TD .09 but never for the TD .15. I tapped them for the standard glow plugs, the turbo plugs and the Nelson plugs - they performed very close to the originals with little increased performance which was the goal. I have plenty of head buttons for Norvel as well as the adapters so I shouldn't run out of them. I have no burned out TD .15 glowheads to adapt to the Nelson threads so won't experiment with them. They are hard to come by.
I have used burned out plugs tapped and drilled for the TD .049, TD .09 but never for the TD .15. I tapped them for the standard glow plugs, the turbo plugs and the Nelson plugs - they performed very close to the originals with little increased performance which was the goal. I have plenty of head buttons for Norvel as well as the adapters so I shouldn't run out of them. I have no burned out TD .15 glowheads to adapt to the Nelson threads so won't experiment with them. They are hard to come by.
.The TD 15 was an outstanding engine for its day-but not without its drawbacks-it was fragile, needed heaps of nitro to perform really well-vibrated far more than it should have-and had a ravenous appetite for glowheads when propped for maximum output. You are quite correct though-that turbo plug and Nelson plugs work well in tapped out heads-standard 1/4-32 UNEF plugs do not-you can typically lose as much as 2-3000rpm-which is way more than most people consider acceptable! The point I was making earlier is that the only option for the TD15 these days is using a std 1/4-32 plug adapter-and this adds insult to injury by being the low compression Medallion type, using a Medallion 15 low compression head, or getting a custom turbo or Nelson head made-and this is a job that few people are doing. I was liucky enough to have a batch done for me by Jon Fletcher-but even than I don't have enough to fit out all my TDs and Olympics.(and it exhausted all my burnt out heads in the process!)
There are ready sources for aftermarket heads for the TD049/051....but there is a real market gap in solutions for the TD09 and TD15......not to mention mundane parts like venturis.....peculiarly-I find it easier to source 15 venturis than 09 ones-despite the TD 15 being out of production for 50 years now-and the 09 only 20....! A pity because the 09 setup is very useful on things like ED super Fury and ED Racers-which suffered from fragile plastc backplates in the later models...
ChrisM
'ffkiwi'
#16
It would probably be possible to get a turbo plug in a rare TD head. If not, then it could maybe be machined away to use the threads and bore out the inside like the Norvel and Merlin two piece heads. I really like the AP .15 better than the old Cox stuff. They have a working throttle, cost less, and have a muffler (which needs drilling out) The weight is not too bad either because it is based on the AP .09. My AP .09 is slightly more powerful than the TD .09 that I have, so the .15 is maybe similar. It really is a .135 or so. Oh yes, then there is a Fora .15. Pretty light, but no throttle, and needs a bladder.
Last edited by aspeed; 07-24-2017 at 05:43 PM.
#17
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It would probably be possible to get a turbo plug in a rare TD head. If not, then it could maybe be machined away to use the threads and bore out the inside like the Norvel and Merlin two piece heads. I really like the AP .15 better than the old Cox stuff. They have a working throttle, cost less, and have a muffler (which needs drilling out) The weight is not too bad either because it is based on the AP .09. My AP .09 is slightly more powerful than the TD .09 that I have, so the .15 is maybe similar. It really is a .135 or so. Oh yes, then there is a Fora .15. Pretty light, but no throttle, and needs a bladder.
True aspeed-but you would have to have an insert with a wide enough base flange to seat on the TD09 or 15 cylinder shoulder.....and that might well be problematic-I am not aware of any current suitable candidates. The only one that potentially might work (almost certainly for the TD09-less certainly for the TD15) is the Cipolla 09 PF7 insert-and these again are in very short supply. The Rossi 09 one might do too-on reflection-and I think Planet Hobby still has these. The problem is -virtually all other 09 or 15 button inserts have a spigot portion on them-so won't seat in a TD09 or 15 without this being machined off-and in the process you a) destroy the combustion chamber shape and b) break the element (because its welded to the edge of the hole on that same face......though I suppose on even further reflection that you could machine up a ring to shrink fit on the spigot section-and hence shim the entire unit up 2mm or so to seat in the correct location........getting to be quite a lot of work though-and would have to be done for each insert button...
ChrisM
'ffkiwi'
Last edited by ffkiwi; 07-24-2017 at 06:31 PM.
#18
No, just modify the threaded original head to preserve the thread, which is hard to make. Then completely make the button with the turbo thread and combustion chamber. I think the thread is an 8mm x 0.75 thread. It was in stock at the one place I went, so it must be fairly common. The bottom taper is 60 degrees like a countersink. The tap drill size is 7.25mm and the small dia. hole I make 3/16" . The only major problem I can see with this method is that the wrench slots may disappear when the hole is bored out. I only have one head for a Cox .15 on a Sportsman, it is not a good TD head. I would make a few, but probably will never use the Sportsman because I can't think of a suitable plane, and there is no muffler or throttle. Our field requires that.
#19
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No, just modify the threaded original head to preserve the thread, which is hard to make. Then completely make the button with the turbo thread and combustion chamber. I think the thread is an 8mm x 0.75 thread. It was in stock at the one place I went, so it must be fairly common. The bottom taper is 60 degrees like a countersink. The tap drill size is 7.25mm and the small dia. hole I make 3/16" . The only major problem I can see with this method is that the wrench slots may disappear when the hole is bored out. I only have one head for a Cox .15 on a Sportsman, it is not a good TD head. I would make a few, but probably will never use the Sportsman because I can't think of a suitable plane, and there is no muffler or throttle. Our field requires that.
ChrisM
'ffkiwi'
#20
I have "converted" most cox head sizes to take Turbo plugs, even the Pee Wee is possible but was a stretch (the plug hangs on by a thread or so...)
There is a thread on the cox forum about it here (I have a different login name there) https://www.coxengineforum.com/t10495-turbo-plug-heads
But I just copied the method first presented by Japanman and AndyW on RCU some 10-15 years ago...
Here are a few pictures of a .15 head;
There is a thread on the cox forum about it here (I have a different login name there) https://www.coxengineforum.com/t10495-turbo-plug-heads
But I just copied the method first presented by Japanman and AndyW on RCU some 10-15 years ago...
Here are a few pictures of a .15 head;
Last edited by Mr Cox; 07-25-2017 at 01:27 AM.
#21
That is great if there is enough meat on the head, but if there is no TD high compression head available, you would need to make something up from a burned out low compression one. Just drill out toa bit over .500 and face off maybe .060" from just below the thread and make a button insert like the Merlin or Norvel two piece plugs. Maybe a button from a Fora could be made to work if you need that extreme compression. It uses the Nelson plug. I will show some pics of my setup again. I make the plug side first and make a .100" shoulder so it is easy to grab with a collet for the second operation. I made 14 blanks of different diameters for different motors like the TTiger .07, .10, .15, ASP .09, .15, and blue head .15 (which isn't blue any more) CS and GZ .049. and LA .10, .15 and .25. They all showed a gain of between 1,000 and 8,000 rpm with the LAs being the lowest and the blue head ASP and the CS .049 the highest at 2,400 and ....8,000 rpm gain. There is also a pic of the Merlin two piece .049 - .06 two piece head and button. That would be the basic idea for making your own button, but it would then be tapped for the turbo plug on the top. I think that should clear it up, there is probably a 12 hour time difference in our replies from NZ. I had to go to get my beauty sleep last night. It worked.
Last edited by aspeed; 07-25-2017 at 05:46 AM.
#22
Here is a pic of the Fora head button, which might work with some mods. It takes a Nelson plug which is a bit bigger diameter than a turbo plug. TechnoHobby Shop I usually get mine from Aerohobby because he is local, but his site is down for a few days. I believe Galbreath makes a Nelson head for the .049s too. Now that Merlin makes them, and Norvel is back, they are not really needed. Probably there is nothing else for the old Cox TD .15 that I am aware of. As I said before, my choice is the AP .15 at this point in time, I made a turbo head for that too, which worked well. As far as choosing motors, the dune buggy market has some choices too, Picco, Novarossi... Almost everything requires machining though.
Last edited by aspeed; 07-25-2017 at 06:05 AM.
#23
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#24
That method is fine if you don't have a lathe. Actually now it is dated, as the Norvel and even the Cox plugs are available again, as well as Merlins which are cheaper and work great on the .049 and .06s. That method will work well on other non Cox/Norvel apps for sure, but a lathe is the best if you have one, at least if only just to keep things centred, There may also be boring and facing operations in most cases as well. Thanks for finding it for reference, as it is quite useful.
Last edited by aspeed; 07-26-2017 at 03:24 AM.
#25
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Here is a pic of the Fora head button, which might work with some mods. It takes a Nelson plug which is a bit bigger diameter than a turbo plug. TechnoHobby Shop I usually get mine from Aerohobby because he is local, but his site is down for a few days. I believe Galbreath makes a Nelson head for the .049s too. Now that Merlin makes them, and Norvel is back, they are not really needed. Probably there is nothing else for the old Cox TD .15 that I am aware of. As I said before, my choice is the AP .15 at this point in time, I made a turbo head for that too, which worked well. As far as choosing motors, the dune buggy market has some choices too, Picco, Novarossi... Almost everything requires machining though.
ChrisM
'ffkiwi'