Topics

670 & 277 engine

Rich Gillen
 

I have never heard of a Polaris Piston being used in a 670, do you have a Part Number? I have heard of the 720 (81mm x 70mm) 721.7cc . I have a pair of 720 Cylinders on the shelf that needs (1) New Sleeve, has a hairline crack. There is a guy on eBay selling the 82mm Sleeves and Pistons for the 670. 

NEW NOS Cylinder Sleeves 82.00mm Bore. These select sleeves are used to turn your 670cc into a big bore using these sleeves and running a 82mm-85mm piston. A lot more and impressive power gains. Please remember std bore 670cc uses a 78mm piston, these sleeves are capable of an 85mm piston. These are for the rotax 670cc engine from 1994-1999.

another 670 BB Sleeve on eBay.

Rotax 277 Manual. Green Download Button at top of page.

Ultralight News 277 Info.

277 Info

I READ Once, you can take your HP@rpm x .1 to figure fuel burn, but I think it's a little higher.

670 92hp@6350rpm. ----> 92 x .1 = 9.2 gph

618UL 73.4hp@6750rpm. 73.4 x .1 = 7.34 gph

582UL 65hp@6500rpm     65 x .1 = 6.5 gph

503UL 50hp@6500rpm     50 x .1 = 5.0 gph

447UL 40hp@6500rpm     40 x .1 = 4.0 gph

377UL 35hp@6500rpm     35 x .1 = 3.5 gph

277UL 26hp@6250rpm     26 x .1 = 2.6 gph

Your 277UL is (72mm x 66mm) 268.4cc. They have rated it at 26hp@6250rpm and 28hp@6400rpm with Rotax's Muffler. A Company called R&D Aero in the 90's who built Tuned Pipes, Dynoed the Stock 26hp 277UL and it made max 25.4hp@6000rpm. Here is the comparion Stock vs R&D Aeros Tuned Pipe which is very Mild.

The 277UL/277F uses a Head/Cylinder (4) Bolt Pattern based on a 100mm Bolt Circle. The 503UL/503F uses the same bolt pattern. The 521 to 670 also uses the 100mm Bolt Circle but use (6) Bolts instead of (4). So All of these can be Big Bored to 82mm. Finding a Piston to work is the Hard part. I have attached a Rotax graph chart for fuel use.

277UL using Rotax graph.
6500rpm = 4.1 gph All GPH Approximate's off Graph.
6000rpm = 3.4 gph At 6000rpm is where it made Max 25.4hp. 3.4 / 25.4 = 0.134.
5500rpm = 2.7 gph
5000rpm = 2.0 gph
4500rpm = 1.4 gph
4000rpm = 1.0 gph

If you look at the comparison of the Stock 277UL and 277UL with R&D's Tuned Pipe it made 30.5hp@6250rpm. If you look close at the Stock 277UL you will see where it starts to lose hp after 5500rpm. Is the exhaust to Restrictive or is the Carb to Small, or both!

A 277 Big Bore (82mm x 66mm) 348.6cc!




1c. 
Re: BMW 1200cc engine
From: John Hoxie
Date: Tue, 05 May 2020 15:11:58 PDT

I read that somone put in Polaris pistons in a 670 to make it a 720. Do you have any info on that? Do you have a fuel burn chart comparing the Rotax engines. I have a 277 for one of my ultralights I am restoring. Is there a way to get a manual on that?

John Hoxie
 

Rich,
thanks for all the info. I didn't realize for Rotax you multiply the hp by .1 to get fuel burn. I'm hoping on my Kasperwing for slow cruise at 4000 RPM. It won't be flying for at least six weeks. Is that true for the 918 and such also?

 
John Hoxie
He is no fool, who gives up what he can not keep, to gain what he can not loose -- Jim Elliot


On Wednesday, May 6, 2020, 12:44:33 PM MDT, Rich Gillen via groups.io <armilite@...> wrote:


I have never heard of a Polaris Piston being used in a 670, do you have a Part Number? I have heard of the 720 (81mm x 70mm) 721.7cc . I have a pair of 720 Cylinders on the shelf that needs (1) New Sleeve, has a hairline crack. There is a guy on eBay selling the 82mm Sleeves and Pistons for the 670. 

NEW NOS Cylinder Sleeves 82.00mm Bore. These select sleeves are used to turn your 670cc into a big bore using these sleeves and running a 82mm-85mm piston. A lot more and impressive power gains. Please remember std bore 670cc uses a 78mm piston, these sleeves are capable of an 85mm piston. These are for the rotax 670cc engine from 1994-1999.

another 670 BB Sleeve on eBay.

Rotax 277 Manual. Green Download Button at top of page.

Ultralight News 277 Info.

277 Info

I READ Once, you can take your HP@rpm x .1 to figure fuel burn, but I think it's a little higher.

670 92hp@6350rpm. ----> 92 x .1 = 9.2 gph

618UL 73.4hp@6750rpm. 73.4 x .1 = 7.34 gph

582UL 65hp@6500rpm     65 x .1 = 6.5 gph

503UL 50hp@6500rpm     50 x .1 = 5.0 gph

447UL 40hp@6500rpm     40 x .1 = 4.0 gph

377UL 35hp@6500rpm     35 x .1 = 3.5 gph

277UL 26hp@6250rpm     26 x .1 = 2.6 gph

Your 277UL is (72mm x 66mm) 268.4cc. They have rated it at 26hp@6250rpm and 28hp@6400rpm with Rotax's Muffler. A Company called R&D Aero in the 90's who built Tuned Pipes, Dynoed the Stock 26hp 277UL and it made max 25.4hp@6000rpm. Here is the comparion Stock vs R&D Aeros Tuned Pipe which is very Mild.

The 277UL/277F uses a Head/Cylinder (4) Bolt Pattern based on a 100mm Bolt Circle. The 503UL/503F uses the same bolt pattern. The 521 to 670 also uses the 100mm Bolt Circle but use (6) Bolts instead of (4). So All of these can be Big Bored to 82mm. Finding a Piston to work is the Hard part. I have attached a Rotax graph chart for fuel use.

277UL using Rotax graph.
6500rpm = 4.1 gph All GPH Approximate's off Graph.
6000rpm = 3.4 gph At 6000rpm is where it made Max 25.4hp. 3.4 / 25.4 = 0.134.
5500rpm = 2.7 gph
5000rpm = 2.0 gph
4500rpm = 1.4 gph
4000rpm = 1.0 gph

If you look at the comparison of the Stock 277UL and 277UL with R&D's Tuned Pipe it made 30.5hp@6250rpm. If you look close at the Stock 277UL you will see where it starts to lose hp after 5500rpm. Is the exhaust to Restrictive or is the Carb to Small, or both!

A 277 Big Bore (82mm x 66mm) 348.6cc!




1c. 
Re: BMW 1200cc engine
From: John Hoxie
Date: Tue, 05 May 2020 15:11:58 PDT

I read that somone put in Polaris pistons in a 670 to make it a 720. Do you have any info on that? Do you have a fuel burn chart comparing the Rotax engines. I have a 277 for one of my ultralights I am restoring. Is there a way to get a manual on that?

Rich Gillen
 


I found this one using a Zenoah G-25 20 hp Engine. MTOW 380 lbs = 172.3651 kg / 10 kg = 17.23651 kw needed = 23.11454 hp needed. With a 160 lb Empty Weight with the Zenoah G-25 20 hp, your 277 should give you the hp you need and still make Part 103. I would look at upgrading the Spars for more useful load, your going to want 5 Gallons. Wiki says,  Zenoah G-25 Producing 22 hp (16 kW) at 6600 rpm.

That Zenoah G-25 Producing 22hp@6600rpm would have made a nice engine for the Q1. 242cc/7cc = 34.5hp with a Tuned Pipe. Zenoah is a Japanese brand with a rich heritage going back over 100 years. Nowadays, Zenoah belongs to Swedish Husqvarna Group and continues to offer outdoor power products as well as hobby engines.


Cascade Kasperwing I-80


Specifications (180)[edit]

Data from Cliche and the Virtual Ultralight Museum[1][2]

General characteristics

  • Crew: one
  • Length: 10 ft (3.0 m)
  • Wingspan: 35 ft (11 m)
  • Height: 11 ft (3.4 m)
  • Wing area: 180 sq ft (17 m2)
  • Gross weight: 380 lb (172 kg)
  • Empty weight: 160 lb (73 kg)
  • Useful Load:  220 lbs
  • Fuel capacity: 2.5 U.S. gallons (9.5 L; 2.1 imp gal)
  • Powerplant: 1 × Zenoah G-25 single cylinder, two-stroke engine, 20 hp (15 kW)
  • Propellers: 2-bladed wooden

Performance

  • Maximum speed: 45 mph (72 km/h, 39 kn)
  • Cruise speed: 35 mph (56 km/h, 30 kn)
  • Stall speed: 18 mph (29 km/h, 16 kn) (at this speed enters into parachute descent mode)
  • Range: 85 mi (137 km, 74 nmi)
  • Service ceiling: 15,000 ft (4,600 m)
  • g limits: +7/-4
  • Maximum glide ratio: 10:1 at 23 mph (37 km/h)
  • Rate of climb: 800 ft/min (4.1 m/s)
  • ===============================================

Specifications (G-25B-1

General characteristics

  • Type: Single cylinder, two-stroke aircraft engine
  • Bore: 72 mm (2.8 in)
  • Stroke: 59.5 mm (2.3 in)
  • Displacement: 242 cc (14.78 cu in)
  • Length: 11.81 in (300.0 mm)
  • Width: 11.57 in (293.9 mm)
  • Height: 14.84 in (376.9 mm)
  • Dry weight: 51 lb (23.1 kg)

Components

Performance


John Hoxie
 

Rich,
I have the spars for the B model. I also have the 5 gallon tank. Where do I look to get a tuned pipe? If I can cruise at 4000 rpm (I flew one 30 years ago and don't remember), that is one gallon an hour. Is it better to use 91 octane with ethanol or 86 octane ethanol free?

 
John Hoxie
He is no fool, who gives up what he can not keep, to gain what he can not loose -- Jim Elliot


On Thursday, May 7, 2020, 12:00:18 PM MDT, Rich Gillen via groups.io <armilite@...> wrote:



I found this one using a Zenoah G-25 20 hp Engine. MTOW 380 lbs = 172.3651 kg / 10 kg = 17.23651 kw needed = 23.11454 hp needed. With a 160 lb Empty Weight with the Zenoah G-25 20 hp, your 277 should give you the hp you need and still make Part 103. I would look at upgrading the Spars for more useful load, your going to want 5 Gallons. Wiki says,  Zenoah G-25 Producing 22 hp (16 kW) at 6600 rpm.

That Zenoah G-25 Producing 22hp@6600rpm would have made a nice engine for the Q1. 242cc/7cc = 34.5hp with a Tuned Pipe. Zenoah is a Japanese brand with a rich heritage going back over 100 years. Nowadays, Zenoah belongs to Swedish Husqvarna Group and continues to offer outdoor power products as well as hobby engines.


Cascade Kasperwing I-80


Specifications (180)[edit]

Data from Cliche and the Virtual Ultralight Museum[1][2]

General characteristics

  • Crew: one
  • Length: 10 ft (3.0 m)
  • Wingspan: 35 ft (11 m)
  • Height: 11 ft (3.4 m)
  • Wing area: 180 sq ft (17 m2)
  • Gross weight: 380 lb (172 kg)
  • Empty weight: 160 lb (73 kg)
  • Useful Load:  220 lbs
  • Fuel capacity: 2.5 U.S. gallons (9.5 L; 2.1 imp gal)
  • Powerplant: 1 × Zenoah G-25 single cylinder, two-stroke engine, 20 hp (15 kW)
  • Propellers: 2-bladed wooden

Performance

  • Maximum speed: 45 mph (72 km/h, 39 kn)
  • Cruise speed: 35 mph (56 km/h, 30 kn)
  • Stall speed: 18 mph (29 km/h, 16 kn) (at this speed enters into parachute descent mode)
  • Range: 85 mi (137 km, 74 nmi)
  • Service ceiling: 15,000 ft (4,600 m)
  • g limits: +7/-4
  • Maximum glide ratio: 10:1 at 23 mph (37 km/h)
  • Rate of climb: 800 ft/min (4.1 m/s)
  • ===============================================

Specifications (G-25B-1

General characteristics

  • Type: Single cylinder, two-stroke aircraft engine
  • Bore: 72 mm (2.8 in)
  • Stroke: 59.5 mm (2.3 in)
  • Displacement: 242 cc (14.78 cu in)
  • Length: 11.81 in (300.0 mm)
  • Width: 11.57 in (293.9 mm)
  • Height: 14.84 in (376.9 mm)
  • Dry weight: 51 lb (23.1 kg)

Components

Performance


Rich Gillen
 


The 277 is 11.8cr, needs Fresh 91+ Octane!

The only thing Bad about 10% Ethanol Fuel is some Fiberglass Fuel Tanks don't like it, and some Fuel Line will get brittle. Tygon Fuel line is Best and has No problem with Ethanol. On my 5 Sleds I run 10% 91 ethanol for the last 12 Years, I have never change fuel pumps or lines. 4 are Oil Injection one is premix. For a Plane I would change them out every 3 Years, Fuel Line, Fuel Pump, Fuel Filter. If your flying year around you always have fresh Gas in it. If you put it away for the winter months at a time, burn out all the ethanol and put some 100LL in it, maybe enough to start it once a month to get some Oil on the internals. I usually put both Sea Foam and Staybil in the Gas for Winter Storage. If you don't want to start it once a month, using some Fogging Oil.

100LL has a 5 Year Shelf life and no Detonation problems.

86/87 is really only Safe for 9.0cr and Pump Gas goes Bad in 6 Months or less. Pump Gas can drop 2 Points in Octane in as little as 3 Weeks.

You can Blend 86/87 with 100LL for a Higher Octane. Once you mix Oil with Gas it also lowers the Octane. If you need 91 Octane, Blend for 93//94 Octane than if it drops in 3 weeks your still Safe. A Good rule is never Blend Gas for more than you will use per Month.

If you Blend Gas you can find plastic Barrels cheap on Craigslist. 4 weekends in a Month, say 8 days Flying a month, 5 Gallons x 8 = 40 Gallons. Barrels come in many Sizes. I say blend for 94 Octane, that way if it drops 2 Points, you still have 92 octane.

 For say 94 Octane using: 86 Low Octane Gallons 0.43 and 100LL for High Octane Gallons 0.57.

Fuel Blending Calc. A 55 Gallon Drum with a blend of 86/100LL mixed 50/50 = 93 Octane.

For 94 Octane using:

87 Low Octane Gallons

0.46   Use this amount in your mixed fuel

100LL High Octane Gallons

0.54   Use this amount in your mixed fuel

For 94 Octane using:

91 Low Octane Gallons

0.67   Use this amount in your mixed fuel

100LL High Octane Gallons

0.33   Use this amount in your mixed fuel

Today, you have to either adapt a Sled Pipe or make your own. There is Jaws, SLP, Speedwerk, AAen, that makes Tuned pipes, but they don't want anything to do with Airplanes, they sight Liability. There are others I haven't checkd them all. You might get by saying it's for a Mini AirBoat.

Building a Tuned Pipe for a 2 Stroke is basically the same except for Narrow or Wide Power band. Here is a good article on How to Build one.  https://www.instructables.com/id/Build-a-Tuned-pipe-for-a-2-stroke/

There is Free Smart Phone Software, or Cheap Tuned Pipe Software out there. Bottom Box you want 2.0 for a Wide Band. You need a Cone Program for making Bends.


This guy makes some nice cheap Software also, that I like best. Pipe Designer and has a nice Cone program.

another brand software.

If you have a Salvage Yard close by, you can buy the metal for Pennys on the Dollar or if your a Good Scounger you can find some on Garbage day.

A Digital Indicator like this is nice for measuring your Ports. I paid like $24 for mine.


Some New Idea's is breaking it in half with a Collar held together with Springs.

A Good Rule of Thumb for our max 6500rpm and using 11.5cr, is it takes 7cc to make 1hp. Figure +/- 1.0cr = 1hp. Going from 11.5cr to 9.5cr = -2.0hp. RPM used = Thrust Made. A 277 using an A/B Gear Drive, a 68" (2) blade is the largest you should use, if a (3) Blade 64" is the largest you should use. If you use the Power to Weight Formula, your MTOW lbs converted to KG, then divide your KG by 10 kg = kw needed, then convert kw to HP. Your plane is under Part 103, 254 lbs with a 277, so you have options to do some upgrades if you want, more HD Spars for more MTOW, Tundra Tires, better Suspension, etc. A 277UL Free Air is lighter than a Fan Cooled.

Rich


2b. 
Re: 670 & 277 engine
From: John Hoxie
Date: Thu, 07 May 2020 19:28:47 PDT

 

Rich,
I have the spars for the B model. I also have the 5 gallon tank. Where do I look to get a tuned pipe? If I can cruise at 4000 rpm (I flew one 30 years ago and don't remember), that is one gallon an hour. Is it better to use 91 octane with ethanol or 86 octane ethanol free?

John Hoxie
 

Thanx Rich,
You're a plethora of info. The 277 will be put on my basic cage with the bungee suspension upgrade. The Zenoah will be put on the cage without suspension & my Kaw 340 is on my float bird. We can't have much fuel stored in the hangar. I'll get 4 gallons 91 octane at gas station in my 5 gal can and have the fuel truck bring 2 gallons 100LL @ $4.99 a gallon (current price).


On Fri, May 8, 2020 at 7:30 PM, Rich Gillen via groups.io
<Armilite@...> wrote:

The 277 is 11.8cr, needs Fresh 91+ Octane!

The only thing Bad about 10% Ethanol Fuel is some Fiberglass Fuel Tanks don't like it, and some Fuel Line will get brittle. Tygon Fuel line is Best and has No problem with Ethanol. On my 5 Sleds I run 10% 91 ethanol for the last 12 Years, I have never change fuel pumps or lines. 4 are Oil Injection one is premix. For a Plane I would change them out every 3 Years, Fuel Line, Fuel Pump, Fuel Filter. If your flying year around you always have fresh Gas in it. If you put it away for the winter months at a time, burn out all the ethanol and put some 100LL in it, maybe enough to start it once a month to get some Oil on the internals. I usually put both Sea Foam and Staybil in the Gas for Winter Storage. If you don't want to start it once a month, using some Fogging Oil.

100LL has a 5 Year Shelf life and no Detonation problems.

86/87 is really only Safe for 9.0cr and Pump Gas goes Bad in 6 Months or less. Pump Gas can drop 2 Points in Octane in as little as 3 Weeks.

You can Blend 86/87 with 100LL for a Higher Octane. Once you mix Oil with Gas it also lowers the Octane. If you need 91 Octane, Blend for 93//94 Octane than if it drops in 3 weeks your still Safe. A Good rule is never Blend Gas for more than you will use per Month.

If you Blend Gas you can find plastic Barrels cheap on Craigslist. 4 weekends in a Month, say 8 days Flying a month, 5 Gallons x 8 = 40 Gallons. Barrels come in many Sizes. I say blend for 94 Octane, that way if it drops 2 Points, you still have 92 octane.

 For say 94 Octane using: 86 Low Octane Gallons 0.43 and 100LL for High Octane Gallons 0.57.

Fuel Blending Calc. A 55 Gallon Drum with a blend of 86/100LL mixed 50/50 = 93 Octane.

For 94 Octane using:

87 Low Octane Gallons

0.46   Use this amount in your mixed fuel

100LL High Octane Gallons

0.54   Use this amount in your mixed fuel

For 94 Octane using:

91 Low Octane Gallons

0.67   Use this amount in your mixed fuel

100LL High Octane Gallons

0.33   Use this amount in your mixed fuel

Today, you have to either adapt a Sled Pipe or make your own. There is Jaws, SLP, Speedwerk, AAen, that makes Tuned pipes, but they don't want anything to do with Airplanes, they sight Liability. There are others I haven't checkd them all. You might get by saying it's for a Mini AirBoat.

Building a Tuned Pipe for a 2 Stroke is basically the same except for Narrow or Wide Power band. Here is a good article on How to Build one.  https://www.instructables.com/id/Build-a-Tuned-pipe-for-a-2-stroke/

There is Free Smart Phone Software, or Cheap Tuned Pipe Software out there. Bottom Box you want 2.0 for a Wide Band. You need a Cone Program for making Bends.


This guy makes some nice cheap Software also, that I like best. Pipe Designer and has a nice Cone program.

another brand software.

If you have a Salvage Yard close by, you can buy the metal for Pennys on the Dollar or if your a Good Scounger you can find some on Garbage day.

A Digital Indicator like this is nice for measuring your Ports. I paid like $24 for mine.


Some New Idea's is breaking it in half with a Collar held together with Springs.

A Good Rule of Thumb for our max 6500rpm and using 11.5cr, is it takes 7cc to make 1hp. Figure +/- 1.0cr = 1hp. Going from 11.5cr to 9.5cr = -2.0hp. RPM used = Thrust Made. A 277 using an A/B Gear Drive, a 68" (2) blade is the largest you should use, if a (3) Blade 64" is the largest you should use. If you use the Power to Weight Formula, your MTOW lbs converted to KG, then divide your KG by 10 kg = kw needed, then convert kw to HP. Your plane is under Part 103, 254 lbs with a 277, so you have options to do some upgrades if you want, more HD Spars for more MTOW, Tundra Tires, better Suspension, etc. A 277UL Free Air is lighter than a Fan Cooled.

Rich


2b. 
Re: 670 & 277 engine
From: John Hoxie
Date: Thu, 07 May 2020 19:28:47 PDT

 

Rich,
I have the spars for the B model. I also have the 5 gallon tank. Where do I look to get a tuned pipe? If I can cruise at 4000 rpm (I flew one 30 years ago and don't remember), that is one gallon an hour. Is it better to use 91 octane with ethanol or 86 octane ethanol free?

Michael Quinn
 

Rich, 

Another major problem that is overlooked are the additives that are put into today's pump gas (but not (yet) in av gas).  

In the past - carburetors were able to keep themselves much cleaner than fuel injectors (esp direct injection).  So they all started adding cleaners to the fuel and these cleaners are very harsh on rubber.  I second the Tygon fuel line - but watch out for any gaskets and bungs you might have that are rubber!

M.


From: Q-Performance@Q-List.groups.io <Q-Performance@Q-List.groups.io> on behalf of Rich Gillen via groups.io <Armilite@...>
Sent: Friday, May 8, 2020 9:30 PM
To: Q-Performance@Q-List.groups.io <Q-Performance@Q-List.groups.io>
Subject: [Q-Performance] 670 & 277 engine
 

The 277 is 11.8cr, needs Fresh 91+ Octane!

The only thing Bad about 10% Ethanol Fuel is some Fiberglass Fuel Tanks don't like it, and some Fuel Line will get brittle. Tygon Fuel line is Best and has No problem with Ethanol. On my 5 Sleds I run 10% 91 ethanol for the last 12 Years, I have never change fuel pumps or lines. 4 are Oil Injection one is premix. For a Plane I would change them out every 3 Years, Fuel Line, Fuel Pump, Fuel Filter. If your flying year around you always have fresh Gas in it. If you put it away for the winter months at a time, burn out all the ethanol and put some 100LL in it, maybe enough to start it once a month to get some Oil on the internals. I usually put both Sea Foam and Staybil in the Gas for Winter Storage. If you don't want to start it once a month, using some Fogging Oil.

100LL has a 5 Year Shelf life and no Detonation problems.

86/87 is really only Safe for 9.0cr and Pump Gas goes Bad in 6 Months or less. Pump Gas can drop 2 Points in Octane in as little as 3 Weeks.

You can Blend 86/87 with 100LL for a Higher Octane. Once you mix Oil with Gas it also lowers the Octane. If you need 91 Octane, Blend for 93//94 Octane than if it drops in 3 weeks your still Safe. A Good rule is never Blend Gas for more than you will use per Month.

If you Blend Gas you can find plastic Barrels cheap on Craigslist. 4 weekends in a Month, say 8 days Flying a month, 5 Gallons x 8 = 40 Gallons. Barrels come in many Sizes. I say blend for 94 Octane, that way if it drops 2 Points, you still have 92 octane.

 For say 94 Octane using: 86 Low Octane Gallons 0.43 and 100LL for High Octane Gallons 0.57.

Fuel Blending Calc. A 55 Gallon Drum with a blend of 86/100LL mixed 50/50 = 93 Octane.

For 94 Octane using:

87 Low Octane Gallons

0.46   Use this amount in your mixed fuel

100LL High Octane Gallons

0.54   Use this amount in your mixed fuel

For 94 Octane using:

91 Low Octane Gallons

0.67   Use this amount in your mixed fuel

100LL High Octane Gallons

0.33   Use this amount in your mixed fuel

Today, you have to either adapt a Sled Pipe or make your own. There is Jaws, SLP, Speedwerk, AAen, that makes Tuned pipes, but they don't want anything to do with Airplanes, they sight Liability. There are others I haven't checkd them all. You might get by saying it's for a Mini AirBoat.

Building a Tuned Pipe for a 2 Stroke is basically the same except for Narrow or Wide Power band. Here is a good article on How to Build one.  https://www.instructables.com/id/Build-a-Tuned-pipe-for-a-2-stroke/

There is Free Smart Phone Software, or Cheap Tuned Pipe Software out there. Bottom Box you want 2.0 for a Wide Band. You need a Cone Program for making Bends.


This guy makes some nice cheap Software also, that I like best. Pipe Designer and has a nice Cone program.

another brand software.

If you have a Salvage Yard close by, you can buy the metal for Pennys on the Dollar or if your a Good Scounger you can find some on Garbage day.

A Digital Indicator like this is nice for measuring your Ports. I paid like $24 for mine.


Some New Idea's is breaking it in half with a Collar held together with Springs.

A Good Rule of Thumb for our max 6500rpm and using 11.5cr, is it takes 7cc to make 1hp. Figure +/- 1.0cr = 1hp. Going from 11.5cr to 9.5cr = -2.0hp. RPM used = Thrust Made. A 277 using an A/B Gear Drive, a 68" (2) blade is the largest you should use, if a (3) Blade 64" is the largest you should use. If you use the Power to Weight Formula, your MTOW lbs converted to KG, then divide your KG by 10 kg = kw needed, then convert kw to HP. Your plane is under Part 103, 254 lbs with a 277, so you have options to do some upgrades if you want, more HD Spars for more MTOW, Tundra Tires, better Suspension, etc. A 277UL Free Air is lighter than a Fan Cooled.

Rich


2b. 
Re: 670 & 277 engine
From: John Hoxie
Date: Thu, 07 May 2020 19:28:47 PDT

 

Rich,
I have the spars for the B model. I also have the 5 gallon tank. Where do I look to get a tuned pipe? If I can cruise at 4000 rpm (I flew one 30 years ago and don't remember), that is one gallon an hour. Is it better to use 91 octane with ethanol or 86 octane ethanol free?

Rich Gillen
 


I personally have found No Problems running Pump Gas, even with 10% Ethanol on any rubber parts, other than Pump Gas goes Bad in 6 months or less. Regular Fuel Line gets Brittle and Cracks over time. Seen many Sleds burn up from not changing there lines. When I bought my used T-Bird I about 12 Years ago, the In Tank Pickup Fuel Line was Standard Black Rubber Gas Line, and it had Swelled to about 3X at the fitting and was about 3/4 Cracked. It had been sitting for about 5 Years inside a nice Shed, the owner had died from Cancer, and the kid was afraid of Heights. So hadn't flown it. It had about 12 hrs on it since rebuilt. He didn't know much about it or what type of Fuel has dad used, but I assumed his dad was burning 10% ethanol in it. But I have never Tested Standard black rubber fuel line left in Gas for 5+ Years. I wish I had taken a Photo of it. I just replaced everything on the Fuel System with Tygon when I got it.

I usually Winterize all my Garden & Yard Tools at the end of Oct.. Usually with Fresh 91 Gas, with some Seafoam & Staybil. Many of my Yard tools won't even start with the Old Gas in the Middle of April, but they use too 10+ years ago, just to show how bad Pump Gas has become. You can throw it on Cement and it won't even light with a match. Now, I just drain it all and use it in my parts Cleaning Tank which sits out side.

This guy makes Good Rubber parts.

Pump Gas with ethanol 25 hrs used in a 2 Stroke. Many 2 Stroke Oils aren't comparable with Ethanol. So always check your 2 Sroke Oils Spec's.

Rich






1c. 
Re: 670 & 277 engine
From: Michael Quinn
Date: Sun, 10 May 2020 05:02:45 PDT

Rich,

Another major problem that is overlooked are the additives that are put into today's pump gas (but not (yet) in av gas). 

In the past - carburetors were able to keep themselves much cleaner than fuel injectors (esp direct injection).  So they all started adding cleaners to the fuel and these cleaners are very harsh on rubber.  I second the Tygon fuel line - but watch out for any gaskets and bungs you might have that are rubber!

M.