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Jan 29, 2017, 05:20 PM
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1/2A Nut's Avatar
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Reverted to stock to see what she can do / rpm increased to 1,334

Norvel Vmax7 Heli Engine 20,510 rpm / MA 5.5x4.5 (1 min 52 sec)

Published on Jan 29, 2017

Litemachines final upgraded engine for their Heli.
New old stock inspected and signed, dated 11/04/02
20,510 best peak / 17.8oz thrust /.255hp / 190.23w / 87.3 mph
25% nitro / 20% oil / Standard plug and head 5 ports Revlite with bronze bushing.

Approximately 4.5oz of fuel ran through thus far. NV was set but not peaked no pressure tap.
Should hit 21k with ease with shorter fuel line and a pressure tap.
Long neck venturi draws fuel very well / fuel line swung up at start venturi had no issues with it.
Last edited by 1/2A Nut; Jan 29, 2017 at 06:00 PM.
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Mar 01, 2017, 07:25 AM
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1/2A Nut's Avatar
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Last yr. I bought some carbon sock in two different sizes to
try this method for pipe making I want something smaller
for the TD .020. Instead of wax I was thinking white foam
then pour gasoline through the pipe to melt it out. Can fab
up a carbon header for it using aluminum ring for the base
something ridged for a good seal. Matt with
is sending me the 11/64 - 40 die to add a RC carb to the
engine making this a unique for the Nano I project. The top
lip of the exhaust ports can be flared open a bit to increase
timing to insure a bit of influx boost.

I will take the Profi .8cc pipe and reduce it down to 40%.
TD .020 being at .33cc this should be in the ball park. I
have forgotten who made this pipe in the pics perhaps
originator will see the post and pipe in
Last edited by 1/2A Nut; Mar 01, 2017 at 07:36 AM.
Mar 01, 2017, 09:06 AM
Dieselized User
gkamysz's Avatar
Beaded foam will leave a terrible surface after melting it away. Extruded foam would be a better choice, even then the surface will be like 80 grit sand paper.

How long would that .020 pipe be?
Mar 01, 2017, 11:17 AM
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Agreed wax would be best.

The size dia.
- stinger would have a 2.5mm outlet
- 12mm where the convergent and divergent meets and
- at the header 5mm.
- 6.5in with 1in header pipe set for 35-36k rpm.
- Prop 3.75x4N / 130+ mph potential.
Last edited by 1/2A Nut; Mar 01, 2017 at 11:23 AM.
Mar 01, 2017, 04:39 PM
Registered User
surfer_kris's Avatar
There was a thread on RCU (possibly around ten years ago) where someone made a pipe or two using wax and a carbon fibre sock. The problem is the epoxy, it doesn't like high temperatures...
Mar 01, 2017, 07:08 PM
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gkamysz's Avatar
Yeah, it would be tough to post cure a high temp resin with a wax plug.
Mar 01, 2017, 08:59 PM
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Something has been sorted out by Bolly and Salisbury Power Pipes.

I have a link to some high temp type epoxy will have to dig it up.
The Salisbury folks offer custom work I have been told.
Last edited by 1/2A Nut; Mar 01, 2017 at 09:11 PM.
Mar 01, 2017, 11:08 PM
Registered User
Small aside from one who was busy Fielding Yama Race bikes.. for their Heyday of early 70's.
Expansion chambers are SONIC devices as invented/developed by W Kaaden .
They employ sonic pressure waves. Which in simple terms means that the chamber material Resonance is CRITICAL. In practice that means Mild Steel. Not SS and certainly not Ali.. SS.. OR glassfibre/carbon resin goop mixes.
An inpeptly designed Mild Steel exp chamber would spontaneously self destruct into a thousand bits of shrapnel.. on the track.. in a race.
Many Yama ones did exactly that. V distressing to all. Most of all to following riders as their tires were instantly shredded.

Truth is Toy airplane expansion chambers are imposters. Like it or not.
Resonance is not even considered, let alone designed for. Appearance seems as all the lip service paid.
Reality is a 'tuned' length of straight tubing gives a 'Pipe' effect. True.. experiment with it.
That's what Moto race engineers did before Kaadens' efforts showed them all up.
Far less effective than a genuine /effective Expansion Chamber, but still an improvement over No pipe.
Fair (good :-) guess as that's what's actually happening with ersatz TOY airplane engine 'pipes'.
Also worth saying, whilst ranting is that Moto 2 strokes produce MORE hp per CC than do toy motors... a lot more.. despite running gasoline... not fuel.
Took me a while to realise that .. alwaystold/ thought was told that wee aero engines were state of the art efforts.
Not true is the reality.
Case in point (for all it matters:-) is that a 30 yr old Yama engine runs ...and idles... in Urban traffic despite a 206 d ex duration.
'nuff said.
No need to explore the late Moto GP 2 stroke machines with their 250k$ 2 stroke engines
Mar 02, 2017, 12:30 AM
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Neat info thank you Bare,

Here is a Italian engine at 50,074 rpm using aluminum .8cc tuned pipe
Happens when I was tweaking the NV on the bench.

Picco P-Zero Full 2nd Vid Octura 1426 (modified) (7 min 6 sec)

Example of the pipe performance with the same engine.
First vid with a muffler with pressure tap:

Picco P-0 .06 /.85cc APC 4.2x4 / 26.57k (1 min 36 sec)

APC 4.2x4 / 26,570k

Picco P-0 .05 / Profi Tuned Pipe - APC 4.2x4 / 28,585 Static (0 min 51 sec)

APC 4.2x4 / 28,585 No pressure tap.

2,015 rpm static boost

Custom Crank / Picco .0519 ci / .85 cc / APC 4.2x4 / 29.473 rpm (1 min 35 sec)

APC 4.2x4 / 29,473 rpm With pressure tap.

2,903 rpm static boost

These folks specialize in making steel cones and they will weld them up.
Taking an example double cone I reshaped to pipe.

Last pic is a cone spun out of flat sheet showing what's possible with
no seams.
Last edited by 1/2A Nut; Mar 02, 2017 at 02:23 AM.
Mar 11, 2017, 10:55 AM
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Tuned pipe design software online.

Last edited by 1/2A Nut; Mar 11, 2017 at 11:43 AM.
Mar 11, 2017, 08:27 PM
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TD .020 with RC Carb Cox 4.5Dx2P Prop (1 min 11 sec)

Uploaded on Mar 11, 2017 Small Cox Logo

TD .020 with RC Carb
G-Mark .030 RC carb threaded to aluminum carb body
Cox muffler, aluminum back plate, 1 shim, Cox 4.5Dx2P prop
17,472 best read open exhaust / 16.1k with muffler 8k idle.
Fuel tank was too elevated to be an ideal setup.
SPI cylinder needs to be shimmed. Stock muffler is restrictive
but nice and quite. . 30.8g as shown with prop and muffler.

The die to cut the threads is: 11/64 - 40. This thread was known
to be used with Singer Sewing Machines making part replacement
more exclusive to being sold by that company.

Matt with EX Model Engines provided the custom die.

Pic shows a cut down 4.5x2 to 3.7x2 better rpm and throttle response.
You have to back cut the RC carb to get good clearance from the muffler
same shape as the Cox .049 carbs. Hex head bolt on the control arm
does a better job binding the arm over the flat head screw / same for
the spinner no kicking props loose withe 1/2A Hornet elect starter!

Last edited by 1/2A Nut; Apr 02, 2017 at 03:32 AM.
Mar 23, 2017, 06:46 PM
flyinglog's Avatar
Hi !

I did convert another one to airplane use, a small Force 15 Car Motor :

Carson Force 15 Flug Conversion (0 min 34 sec)

Video is a bit crappy, but the important things are visible. I did read 23500 with an F2D Propeller (slim 6,5x3,7 Prop)
Fuel is 10% Nitro
There are missing around 1000 rpm, it should get to 24500 with this Prop in "Stock" form. Bearings are a bit stiff, i want to replace them with C3 ones. Still needs running in, though.

Best regards,
Mar 23, 2017, 07:30 PM
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Hi Sebastan, good to see you sharing on RCU again thank you.

23,498 many times
23,579 many times
23,659 3 times
23,740 two times it hit a brief peak

Looking at the more steady number:
23,579 rpm / 83 mph static / .623 hp / 465 W / 46 oz thrust!

Great a most worthy conversion!

Force Motor .15 Size 2.5 cc OS-shaft
Carson - 500901008

Specs from manufacture:
High-performance allrounder with 2.5 ccm. Side exhaust.
Version with pull-starter, slide carburettor and SG-shaft.
Technica data: Cylinder bore: ABC capacity: 2.49 ccm
performance: 0.9 kW (1.2 PS) revolutions: 29.000 rpm bore:
15 mm deviation: 13.6 mm weight: 262 g
Last edited by 1/2A Nut; Mar 23, 2017 at 07:39 PM.
Mar 23, 2017, 07:57 PM
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My new 1.14cc / .07 cu. in. Rigger Project SH-.07 car engine conversion.

SH-.07 Outrigger Hydro / Bench Test 38,680 rpm (0 min 43 sec)
Mar 23, 2017, 08:33 PM
Registered User
So what is involved with converting the car engines over to airplane use? Are there stock parts available to do it, or do you need to be able to machine parts from scratch? I've often thought about doing it if it's not a huge hassle. I used to have an OS .12 CZ that came with a great plane gas cub kit and it was one of my best running engines in that size range, but when I try to find them now all I can find is the RC car version.


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