Engine for pattern flying
03-11-2004 | 03:22 PM
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From: Silverdale WA
Engine for pattern flying
gentlemen, I am building a tiger 60 to be used for pattern flying and I have a couple of questions:
1. if i go with a 2 stroke Either a .61 or .91 engine) should i use a perry pump or cline regulator? At what point is a regulator and pump absolutely necessary?
2. I want to angle the engine so the exhaust flows out the bottom of the plane ( I have a freestyle I did this with and i like it much better). OR can i mount the engine straight and use a pitts muffler? If I use a pitts muffler? What should I be aware of? I have seen pilots use customer mufflers and have their engines not work right due to insufficient back pressure.
3. If I go with a 4 stoke ( and I am not familiar with them at all)(but love their sound) do they need a perry pump or cline regulator?
4. On a 4 stroke I understand you have to reinforce the fuel tank due to hight pressure? Is this correct or is there a special name brand of tanks for 4 strockers that is heavy duty enought?
and and all help is appreciated.
03-11-2004 | 03:53 PM
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RE: Engine for pattern flying
It is totally unnecessary to do anything to a fuel tank for a four stroke, not even for a YS engine, although some guys wrap them in shipping tape, I've never had a tank split or even leak with my YSs or my MDS 2.18 which pressurizes a tank harder than a YS does. If you want to fly pattern like and have an engine with lots of smooth steady torque, get a YS and you'll love it and you can position it any way you like and it will run the same.
03-11-2004 | 04:09 PM
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From: San Francisco, CA
RE: Engine for pattern flying
The Tiger 60 is probably a decent entry level Pattern Flyer as such but I think there are much better flying choices to be made such as the various Kaos series and sizes of kits by Bridi. Even though Joe Bridi is out of business there are still many of his well known and well proven designed Pattern kits still easily available on the net or even here on RCU
in the market place. He made many Kaos variants which were famous and successful Pattern Contenders.
Pumps are generally used on engines that either have poorly designed carbs OR as a manner of relocating fuel tanks to the CG to minimize trim changes during a flight when fuel is burned off making the nose lighter and the tail heavier. Engines manufactured with internal or backplate mounted pumps suit these applications well. Pumped engines also seem to work better in situations where they are inverted compared with non pumped engines.
If you decide to stay with the Tiger 60 then any reliable 60 size 2 stroke 0r 90 size 4 stroke will be more than adequate but since the Tiger 60 is a"cheek cowl" design you will need to modify the cheeks
by partial or complete removal if you want the engine in other than straight up and down configuration or are considering the use of a Pitts style exhaust but remember Pitts systems are designed mainly for fully cowled appications and can sometimes make an engine hard to tune so it runs reliably and you absolutely require a reliable engine for Pattern flying.
There are lots of really nice 60-90 size Pattern ARFs out now - take your pick.
in the market place. He made many Kaos variants which were famous and successful Pattern Contenders.
Pumps are generally used on engines that either have poorly designed carbs OR as a manner of relocating fuel tanks to the CG to minimize trim changes during a flight when fuel is burned off making the nose lighter and the tail heavier. Engines manufactured with internal or backplate mounted pumps suit these applications well. Pumped engines also seem to work better in situations where they are inverted compared with non pumped engines.
If you decide to stay with the Tiger 60 then any reliable 60 size 2 stroke 0r 90 size 4 stroke will be more than adequate but since the Tiger 60 is a"cheek cowl" design you will need to modify the cheeks
by partial or complete removal if you want the engine in other than straight up and down configuration or are considering the use of a Pitts style exhaust but remember Pitts systems are designed mainly for fully cowled appications and can sometimes make an engine hard to tune so it runs reliably and you absolutely require a reliable engine for Pattern flying.
There are lots of really nice 60-90 size Pattern ARFs out now - take your pick.
03-11-2004 | 11:04 PM
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From: Merrimack,
NH
RE: Engine for pattern flying
[quote]
1. if i go with a 2 stroke Either a .61 or .91 engine) should i use a perry pump or cline regulator? At what point is a regulator and pump absolutely necessary?
A pump/regulator is seldom "necessary", but often nice to have. Main benefits of pump/regulator are the freedom to put fuel tank on (or preferably just forward of) the CG; consistent fuel feed regardless of flying attitude and level of fuel in tank; and the elimination of siphoning from tank to engine, flooding engine, hydro-locking an inverted mount engine. These problems can also be minimized or avoided by judicious tank placement and by fueling and starting plane upside down (so inverted engine is right side up). I see this ploy used from time to time, but I don't like flipping an airplane with engine running.
When you say .61 or .91, the general consensus in the pattern world & elsewhere is that the .61 two-stroke is virtually obsolete, in that there are so many engines in the .75 displacement category that have the same size crankcase but enlarged combustion cylinder so they weigh less than the .60 but have more power. So the range of choice is really from .75 to .91. There's no need to ever buy a .60 size engine again.
2. I want to angle the engine so the exhaust flows out the bottom of the plane ( I have a freestyle I did this with and i like it much better). OR can i mount the engine straight and use a pitts muffler? If I use a pitts muffler? What should I be aware of? I have seen pilots use customer mufflers and have their engines not work right due to insufficient back pressure.
You can mount a two-stroke with the cylinder rotated to the eight o'clock position and have the stock muffler angled down at the six o'clock position. (Maybe that's how you did your freestyle.) There are Pitts for side-mount and Pitts for inverted mount. If back pressure is a problem, blocking off one of two vents is a solution, as is use of a pump.
3. If I go with a 4 stoke ( and I am not familiar with them at all)(but love their sound) do they need a perry pump or cline regulator?
A 4-stroke does not "need" a pump/regulator any more than a 2-stroke, but again, they offer advantages. The popular 4-strokes in the sport world are OS and clones (Magnum, ThunderTiger, etc.) and Saitos. Fitting a pump or regulator to one of these adds expense and a little headache. In the pattern world, the far-and-away favorite power solution is the YS. The YS comes with an excellent integrated pump & regulator for little more than an OS or Saito. Plus the YS comes with supercharging (puts more oxygen into the combustion cycle), which the others do not. Result is YS outpowers the others by a wide margin.
4. On a 4 stroke I understand you have to reinforce the fuel tank due to hight pressure? Is this correct or is there a special name brand of tanks for 4 strockers that is heavy duty enought?
Some of the cheaper ARF tanks have been known to leak or rupture from pump pressure (which applies only if the 4-stroke is pumped, which most are not unless they're YS). I've used Dubro, Hayes & Sullivan tanks (as well as ARF tanks) with YS engines, no strapping, no leaks. When the tank is under pressure, you'll see it swell up somewhat, like puffy cheeks, but if you have your stopper screwed in tight you'll be OK. The routine with YS tanks is to open the vent line when you land your plane, so the tank does not hold pressure for long periods.
Your Tiger 60, with 70" wingspan and 855 sq in wing area and 7.5 lb advertised weight will easily carry a .91 size four-stroke, which will be a few ounces heavier than a comparable two-stroke. The YS .91 has been discontinued in favor of the YS 1.10, which is same size crankcase bored out for more power and an ounce lighter than the .91. Used YS .91's are readily available, but I would only buy NIB or from someone I trusted. A new YS 1.10 from Central Hobbies will run you $330 or so, while a NIB .91 from Central was $275 while they still had them. You can't make a better investment if you are attracted to pattern flying.
If you're drawn to a less expensive powerplant, let me say I started pattern on a light 60 size aerobatic ARF with Magnum .91 XLS 2-stroke ($149), side-mounted with Jett muffler (quieter, more RPM than stock muffler, cost ~$75), no pump, no regulator, tank behind firewall. I flew this with 15%, 20% and even 30% nitro. At the high nitro levels it would start backwards sometimes, but on the whole it loved nitro. I flew this plane hard my first season, only problems were pitch & roll coupling to rudder. When those were mixed out, it flew beautifully. The plane has been re-kitted, and the powerplant will fly again.
The Tiger will be a good pattern trainer. I hope you're using two aileron servos, rigged as a taildragger. Keep the throws conservative. Futaba 9001 coreless servos @ $30 from Tower are great value for precise control on all surfaces.
After your Tiger is in the air, take a look at the CA Widebody 60. Have a great flying season!
1. if i go with a 2 stroke Either a .61 or .91 engine) should i use a perry pump or cline regulator? At what point is a regulator and pump absolutely necessary?
A pump/regulator is seldom "necessary", but often nice to have. Main benefits of pump/regulator are the freedom to put fuel tank on (or preferably just forward of) the CG; consistent fuel feed regardless of flying attitude and level of fuel in tank; and the elimination of siphoning from tank to engine, flooding engine, hydro-locking an inverted mount engine. These problems can also be minimized or avoided by judicious tank placement and by fueling and starting plane upside down (so inverted engine is right side up). I see this ploy used from time to time, but I don't like flipping an airplane with engine running.
When you say .61 or .91, the general consensus in the pattern world & elsewhere is that the .61 two-stroke is virtually obsolete, in that there are so many engines in the .75 displacement category that have the same size crankcase but enlarged combustion cylinder so they weigh less than the .60 but have more power. So the range of choice is really from .75 to .91. There's no need to ever buy a .60 size engine again.
2. I want to angle the engine so the exhaust flows out the bottom of the plane ( I have a freestyle I did this with and i like it much better). OR can i mount the engine straight and use a pitts muffler? If I use a pitts muffler? What should I be aware of? I have seen pilots use customer mufflers and have their engines not work right due to insufficient back pressure.
You can mount a two-stroke with the cylinder rotated to the eight o'clock position and have the stock muffler angled down at the six o'clock position. (Maybe that's how you did your freestyle.) There are Pitts for side-mount and Pitts for inverted mount. If back pressure is a problem, blocking off one of two vents is a solution, as is use of a pump.
3. If I go with a 4 stoke ( and I am not familiar with them at all)(but love their sound) do they need a perry pump or cline regulator?
A 4-stroke does not "need" a pump/regulator any more than a 2-stroke, but again, they offer advantages. The popular 4-strokes in the sport world are OS and clones (Magnum, ThunderTiger, etc.) and Saitos. Fitting a pump or regulator to one of these adds expense and a little headache. In the pattern world, the far-and-away favorite power solution is the YS. The YS comes with an excellent integrated pump & regulator for little more than an OS or Saito. Plus the YS comes with supercharging (puts more oxygen into the combustion cycle), which the others do not. Result is YS outpowers the others by a wide margin.
4. On a 4 stroke I understand you have to reinforce the fuel tank due to hight pressure? Is this correct or is there a special name brand of tanks for 4 strockers that is heavy duty enought?
Some of the cheaper ARF tanks have been known to leak or rupture from pump pressure (which applies only if the 4-stroke is pumped, which most are not unless they're YS). I've used Dubro, Hayes & Sullivan tanks (as well as ARF tanks) with YS engines, no strapping, no leaks. When the tank is under pressure, you'll see it swell up somewhat, like puffy cheeks, but if you have your stopper screwed in tight you'll be OK. The routine with YS tanks is to open the vent line when you land your plane, so the tank does not hold pressure for long periods.
Your Tiger 60, with 70" wingspan and 855 sq in wing area and 7.5 lb advertised weight will easily carry a .91 size four-stroke, which will be a few ounces heavier than a comparable two-stroke. The YS .91 has been discontinued in favor of the YS 1.10, which is same size crankcase bored out for more power and an ounce lighter than the .91. Used YS .91's are readily available, but I would only buy NIB or from someone I trusted. A new YS 1.10 from Central Hobbies will run you $330 or so, while a NIB .91 from Central was $275 while they still had them. You can't make a better investment if you are attracted to pattern flying.
If you're drawn to a less expensive powerplant, let me say I started pattern on a light 60 size aerobatic ARF with Magnum .91 XLS 2-stroke ($149), side-mounted with Jett muffler (quieter, more RPM than stock muffler, cost ~$75), no pump, no regulator, tank behind firewall. I flew this with 15%, 20% and even 30% nitro. At the high nitro levels it would start backwards sometimes, but on the whole it loved nitro. I flew this plane hard my first season, only problems were pitch & roll coupling to rudder. When those were mixed out, it flew beautifully. The plane has been re-kitted, and the powerplant will fly again.
The Tiger will be a good pattern trainer. I hope you're using two aileron servos, rigged as a taildragger. Keep the throws conservative. Futaba 9001 coreless servos @ $30 from Tower are great value for precise control on all surfaces.
After your Tiger is in the air, take a look at the CA Widebody 60. Have a great flying season!
