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Scary stuff I was wincing in fear!

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Scary stuff I was wincing in fear!

Post  1/2A Nut on Sun Sep 23, 2018 5:37 pm

Ok as most folks here know I am a rpm speed freak!
Scary as the TD is rated for 25k static it has been well exceeded.
Today a new milestone has been passed. For awhile now I have been
wanting to test a Nelson plug with a Profi 1/2A tuned pipe the deed is done:


Published on Sep 23, 2018
Prop Carbon Blend HQ 4x4.5
Static 28,100 rpm peak no needle tweak very thirsty
9.17oz thrust / .184hp / 137.3w / 120mph pitch speed!
9.2" MRP (mean reflective point) 30% nitro / 20% castor / no pressure tap.
+ 2,907 rpm improvement over the first effort see video below.

This is the hottest static test to date of any of my 1/2A Tee Dee's
I used the same size bullet spinner to keep the test the same
as previous with Cox HC glow plug. I have a custom made
bullet spinner that is lower weight and will prove to add a bit
more rpm on the top end.


Note the Lil speedy hit 31k unloaded at 118 mph with a 4P prop.
The 4x4.5 should hit 33.8k unloaded at 144 mph.  Given the rpm
I will tame it down with a 4.2x5.5 prop at 28-30k unloaded 146-156 mph.
The 4x4.5 was just to stage on the pipe for bench testing.



Published on Aug 3, 2016
Cox TD .050 / Profi Tuned Pipe / 25,193 Static - HQ Prop 4 x 4.5
Static 7.3 oz thrust / .132 hp / 99w / 107.3 mph /
9.3in MRP / 140 deg timing / Pipe set for 25,215 rpm!
The above vid used a pressure tap.


Perhaps Greg will be willing to run a batch of headers for the TD .049
What I am currently using took quite a bit to mod for use.



The yellow rubber band was to insure I had a good seal / didn't want to use a zip tie for this test.


Current Speed Records:




This is a 28" span Nano proved to be a bit too much float time on landings lending me to want a new version which will be
reduce to an over all size span of 25" Made just for the engine used in the bench test.



Published on Feb 10, 2018
NANO III / 9oz / 28" span / APC 4.22x5.5
Best pass 26,647 rpm / 139 mph prop speed
Static 20,370 rpm / .106hp / 79w / 106 mph PS / 6oz thrust
1oz fuel / 25% nitro / 20 castor
With speed, the sound follows behind the plane neat effect.
Checked all passes found the best per posted vid:
Per Audio RPM Gauge 26,647
Per Prop Calc 139 mph
Per Doppler Wav. Scope software 136 mph / 219 Kp/h

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Last edited by 1/2A Nut on Wed Sep 26, 2018 2:55 pm; edited 6 times in total
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Re: Scary stuff I was wincing in fear!

Post  crankbndr on Sun Sep 23, 2018 6:42 pm

That sure is some impressive numbers!! I was wondering what kind of wear you see on the crankcase and piston, rod socket after runs like that?
And a little more nitro please. lol!
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Re: Scary stuff I was wincing in fear!

Post  ticomareado on Sun Sep 23, 2018 7:06 pm

1/2A Nut sure has got it going on in the eyesight and digital dexterity department. Light years ahead of this old slo poke head. What kind of R/C gear is being used here?
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Sun Sep 23, 2018 7:23 pm

Thank you gents! Thumbs Up

Yes more nitro for the record flights most likely fresh 35-40%  Eyebrows

Ticomareado there is a build thread of many size Nano planes if you do a search shows
weights, gear , props, plane design to builds it's all shown so folks can make one if
they wish. The thing is these can fly on less power and make good flying sport planes
for breezy day flying.

I have had no trouble with small props up to 31k unloaded. The trick is don't let them
run static too long, get the plane up and flying unloaded. Also keep to lean mean low
weight planes to avoid damaging the engine. The Nano in the vid did just fine many
test flights the engine's ball socket was reset prior to flight / prop testing, was checked
after 4 different props sizes tested about 18-20 flights in total the socket fit was still good.
Testament to no slop spinner, balanced props / lean plane and low weight props with
out bulky airfoils or wide blades. I use 20% castor it does rob some rpm but helps to keep
these engines alive and well. Perhaps a 4x5.5 prop will hit 150 mph with the next
Nano design will post a vid of it for sure. Need to hit 28.8k rpm which is doable.
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Re: Scary stuff I was wincing in fear!

Post  Dave P. on Sun Sep 23, 2018 9:56 pm

GOOD LORD!  That was fun!  I want one!

Is that a custom carb body?  And I'd like to hear more about the head.  Sorry if you've addressed that before.  Sign me up for a header if Greg cranks some out.  My neighbors will hate me.

Kuddos to your reaction time!  That's some flying.


Last edited by Dave P. on Sun Sep 23, 2018 10:00 pm; edited 2 times in total (Reason for editing : Misspelling. My thumb is too big for my phone apparently)
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Mon Sep 24, 2018 12:45 am

Thank you Dave! Thumbs Up

I had to modify it from a cox car muffler. (See pic) the front exhaust port is blocked off with a brass shim.
I converted the engine into a FIRE TD .050 To improve flow I filed out the header exit which in stock form is suppressing
quite a bit. A good manifold design with a more breathable header will only improve things, I imagine another 800+ rpm static.
A extension was put on the header to get 9.2" MRP. The Galbreath glow plug adapter and Nelson plug helped seal the deal with
a increase of 2,907 rpm over the first test with a stock high compression plug. The bench test needed the 4x4.5 to get on the pipe.
I would not dare try to fly with it as rpm will jump up 5k+




The HQ carbon blend prop has been proven to handle higher rpm the Cox engine can't do much more than 32k with
a sleek low weight airframe so the prop was tested with a sport .05 car engine / with bearings and Profi pipe here is a vid:



Published on Jul 24, 2016
Best pass 36,747 rpm gives a theoretical 157mph potential from a HQ 4x4.5 prop per audio tach from
brief bursts of rpm past camera. With the right size plane the prop speed can be used to it's full advantage.
Per Doppler wave analysis: 238 kmh / 147.89 mph best pass. Down wind shallow dives gets the rpm / speed up,
Prop is too small into the wind or when pushed in steady banking turns with the larger DART. Peak speed is brief
average speeds much lower. Wing is 106sq. in. / 31.5" span 11.3oz RTF much bigger bird then the Nano.

The bruiser TD .09 had it's turn with the DART too:



Published on Jul 2, 2016
Best level pass 143mph / per prop calc / APC 5.25x6.25E
Wavescope: 232.07 kmh / 144.2mph /down wind / 21,960rpm
The reading was taken at 1.52mins into the vid. Temp 96F
Static 17.1k rpm at launch / 9.52oz / 101mph / .167hp / 125w
30% nitro / 20% castor / 31.5 inches 106 Sq. In. wing / 11.7 oz RTF
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Re: Scary stuff I was wincing in fear!

Post  balogh on Mon Sep 24, 2018 4:39 am

Congrats Brad!! I am still experimenting with a similar setup. Is your Needle Valve in the Tarno carb a Norvel part? It looks like one but in any way is differentthan my Tarno NV.
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Mon Sep 24, 2018 7:22 am

Thank you Andras Thumbs Up
It is the second generation version of the Tarno carb.
The one of the left has a O ring to help seal the NV the other has a drag nut to help seal the NV
Flying

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Re: Scary stuff I was wincing in fear!

Post  getback on Mon Sep 24, 2018 9:51 am

Good stuff Brad , you are putting out some good numbers , if Greg makes a run of the tuned pipes let us know I would bee interested myself . Thanks for taking the time and putting in the efforted Small Cox Logo
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Mon Sep 24, 2018 10:15 am

Thank you Eric Thumbs Up

He may not have the capacity for 1/2A size, my request was for the manifold / header which is in his wheel house.
The Profi 1/2A pipe can be bought out of California it is of course shipped into the states from the Ukraine.

http://www.hobbyclub.com/index.php?main_page=index&cPath=44_202

Speeddomingoe on ebay (Alberto) gets them in as I have described before in the past and posted links to his sales page.
I have bought 5 of them from him at 65 dollars shipped ea. When they show up they go like hot potato's!

https://www.ebay.com/usr/speeddomingoe
speeddomingoe (556 sales) 100% positive feedback

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Re: Scary stuff I was wincing in fear!

Post  getback on Mon Sep 24, 2018 11:51 am

Thanks Man , I saved that seller this time LOL I have a few of those Car exhaust manifolds you show a pipe would bee nice ! Babe Bee .049 Devil
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Mon Sep 24, 2018 7:36 pm

Yes those stock Cox car mufflers can be useful, I have flown with one but it was not
opened up as I have shown with the tuned pipe. The power loss was about 18%  in stock form.



Published on Feb 15, 2015

Skorch - 5ch RC plane Cox TD 049 With Cox Car Muffler

Test flight  APC 4.75 x 4  / RC carb and car muffler. Launched with some down elevator close call on the save.
This vid is more of a trim flight cut short.  Best pass with muffler 18,476 rpm / 70 mph per prop calc.
The plane does about 85 mph without the muffler.
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Tue Sep 25, 2018 4:26 am

FYI update:
Greg is willing make some CNC .049 manifold / headers so folks can add tune pipes, exhaust extensions, mufflers etc.
In discussion of the design will keep you posted there are also other efforts in the works, summer time
had slowed down free time for new items. There was a delay in getting the right tooling for some of those
offerings will keep you posted. Fall / Winter time will be more productive for 1/2A offerings.

Here is my preliminary submittal for the manifold / header:
The measurement for the cylinder to slip through needs to be .59" as the cylinder is .58"


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Last edited by 1/2A Nut on Wed Sep 26, 2018 2:57 pm; edited 2 times in total
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Re: Scary stuff I was wincing in fear!

Post  fredvon4 on Tue Sep 25, 2018 11:58 am

Brad is there a way for me to get on any waiting list for 2 of the headers?
Pleas advise
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Tue Sep 25, 2018 2:41 pm

Yes Fred Thumbs Up , just by making mention of it here will allow me to gauge interest and quantities.

I plan to buy 4 of them myself two for flying, one for bench testing setups leaving one spare.
Will notify respondents from this thread via PM when they are ready and provide a link to get the
ball rolling for the masses. Always will put the word out we want to help Greg help us.


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Re: Scary stuff I was wincing in fear!

Post  MauricioB on Wed Sep 26, 2018 10:41 am

[quote="1/2A Nut"]Ok as most folks here know I am a rpm speed freak!
Scary as the TD is rated for 25k static it has been well exceeded.



Friend! ... awesome! Beer Cheers
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Wed Sep 26, 2018 10:33 pm

LOL Mauricio!!! Thank you! Thumbs Up

Update getting closer to actual:

Down to the expert skills of the CNC machinist now.
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Re: Scary stuff I was wincing in fear!

Post  Dave P. on Wed Sep 26, 2018 11:01 pm

Too cool! cheers

A question for you Brad if you don't mind, how do you go about indexing the cylinder so the exhaust port is directly aft?
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Re: Scary stuff I was wincing in fear!

Post  Jason_WI on Wed Sep 26, 2018 11:16 pm

I thought 25k rpm was the event horizon for the ball socket in the piston. Cross it and bad things happen. Impressive and I hope it holds together.
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Thu Sep 27, 2018 12:41 am

Thank you  Dave!  Thumbs Up
Most of us have many cylinders I have 3 that face aft. However you can buy cylinder shims from Cox International
and perhaps Ex Model Engines have them too. If you have two head gaskets and add a shim just go with 1 head gasket
to keep the compression up. Another method is to file down the case a hair then set the cylinder and see which direction
the ports seat at. Note you don't have to be directly aft. for the header to work as long as it's within the window of the
exhaust port your good to go.

Thank you Jason  Thumbs Up
I have flown bit past 31k unloaded with a 4.1x4.1 modified narrow here in this example 30.5k rpm
Trick is: speed prop, small plane, low weight and 20% castor. Don't use old piston assemblies for speed or if for high thrust
save the old known pistons for lessor work
RC unloaded is not as much stress as round and round dragging lines and larger
props at 25k. The Nano III has flown to 27k many times with no issues using a 28" span wing. Best speed with a TD .05 engine to
date is 141 mph pitch speed with a 5" pitched prop hit 29,780 rpm. For speed planes always set the ball socket with a reset tool it
will hold up much better. I oil the ball socket then set with the ball socket tool. I will check after so many trips to the flying field by
taking the glow plug off and pressing down the cylinder with my finger then rotate the prop back and forth feeling for a loose socket,
easy to check without taking the cylinder off.  Many many years of flying 1/2A Cox engines I have yet to snap a conrod or destroy a
socket yet. The most abuse I have ever put a Cox engine through has been with RC boats spinning past 34k as the hull pops out of the
water dancing on the chop. I have worn out some compression though but fixable with less head shims, ground down cylinder tops and
taking down the glow plug footing some, keeps them running hot. Really most of us don't wear out engines this takes quite a bit or running
to do as sport users.


Published on May 7, 2016

TD .049 /SPI / Throttle Sleeve Ports Allow SPI function / Prop 4.1 x 4.1N  / 30% Nitro
Static 24,790 rpm / 7.4oz thrust / .127hp / 94.74w / 96.2 mph / 6.19oz RTF
Unloaded 30,492 best on Vid 1 / 118.4 mph per prop calc.
Doppler reading has it at 118mph per pass at 1:47mins into the vid.
Hard tank no pressure tap. 3.7g servos. Cox low compression plug
3mins 20sec of run time on 15cc tank. 16.5"x4" span wing 66sq. in.
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Thu Sep 27, 2018 3:58 pm

See pic anyone besides myself know what I have here  Eyebrows

Custom performance TD .020:
- Plug adapter for Nelson flat coil inserts
- 128 TPI threaded NV
- Aluminum tank top vent tube and overfill micro hole.
- Thrust washer for prop plate
- Cylinder shim for optimum head clearance
- Very high compression engine
- Benched to run a APC 4.2x2 at minimum static: 27,000 rpm

Shown with a 3.75 x 3E prop good for thrust and speed.  
Pipe in if you have some knowledge to share about the origin of the fuel tank etc.




Last edited by 1/2A Nut on Thu Sep 27, 2018 9:59 pm; edited 2 times in total
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Re: Scary stuff I was wincing in fear!

Post  roddie on Thu Sep 27, 2018 6:52 pm

Congratulations Brad. I have followed your experimental-work on hobby-engines and radio-control application. Regarding the "Cox" products.. I salute you for the time and dedication that you've invested in obtaining the "absolute-maximum" in performance; especially from the Cox engines. Your performance-videos and documentation are nothing-short of "thrilling" for the enthusiast!

Thank You for helping to keep the "Cox" name alive! That's ultimately why we all "tune-in" here! Thumbs Up Thumbs Up
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Re: Scary stuff I was wincing in fear!

Post  Dave P. on Thu Sep 27, 2018 9:05 pm

I'd like to second that emotion.  I've gone back through searches to some of your posts and videos and I have to say that you are an inspiration.  Can't tell you how many times I said "Holy Crap!"  Thanks for that!

I Love This Forum!
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Re: Scary stuff I was wincing in fear!

Post  1/2A Nut on Thu Sep 27, 2018 9:36 pm

Thank you Roddie and Dave! much appreciated! Thumbs Up

Good stuff happening for the 1/2A movement, we are lucky to have a place
to document our efforts for others to enjoy and pursue their own projects
with a higher level of appreciation. These smaller IC power plants make
local flying fun without the need to travel far to get some flights in. What
we do in our time and share here will help make it enticing for the next
generation of small engine enthusiasts.

Airplane
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Re: Scary stuff I was wincing in fear!

Post  Dave P. on Thu Sep 27, 2018 9:46 pm

"Believe it or not, that's at idle." as it zings by at 80 knots.

ROFLMAO

All I can say is Holy Crap!
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Re: Scary stuff I was wincing in fear!

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