Have you ever hear of this?
12-11-2006 | 05:40 PM
#1
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From: Mesa,
AZ
Have you ever hear of this?
I recently built and maidened my Nitro Planes Bobcat-50. This is a pusher configuration with a Tower Hobbies .75 turning a 12x6P (pusher) Zinger.
Now here is where the story gets interesting: After three weeks of either "honey I must work all weekend you'll need to watch the kids" or too much wind, finally Saturday the wife gets off a little bit early and hurries home.
Truck is all loaded, did I forget anything, oh well too bad, I make a flying trip (no pun intended) to the flying field at 3 pm.
(Now I broke this engine in by a process of leaning and richining and I only decided to fly it because the engine broke in to the point that it insisted that I lean the low end needle to get it to start reliably and it would get "up on the pipe" quite nicely
.)
Arrive at field 3:25 "come on son help me unload we don't have much time", get unloaded and I make one flight with my fun fly airplane to knock the dust off.
Fuel up the Bobcat, fuss with fine tuning the low end for 10-15 minutes, make a few dry runs...everything checks out, "I may really hafto do this".
Top off fuel tank....out on the runway...full power.....nose wheel turns and I give the Bobcat its first badge of honor a scraped wing tip.
Ciricle around "ok I know shes gonna go left a little on takeoff".....full throttle almost to peak and then it levels off...."crap too far to stop now or its ditch in the desert" I stay on the runway as long as possible pull back on the stick and she rises into the air reluctantly.
(At this point I thought there was no way I was not going to turn my ARF back into a balsa kit.)
Ok well the engine is running very very rich but it's running (this is a good thing I think to myself) and I begin to realize I don't have enough elevator to gain altitude very fast, swtich to high rates "ahh thats better". I and the Bobcat continue to fly at full throttle "feeling like it could fall from the air at any moment" and I get it trimmed out "whew that was scary" and just then I realize I hafto land a plane that might not make a go around.........
The Bobcat feels like it crawling around the sky just waiting for an excuse to commit suicide, but I steady my nerves make a few fly bys a couple of rolls and test out the stall parameters. (she would not turn at this speed without tip stalling). "holy batcrap catman" I think to myself.
Well on one particular turn comming back to the flight line I realize "hey I'm pretty low...this it it now or never.....LANDING!!!!!"
Well I got her down and gave her another battle scar you guessed it I scraped the other wing tip, ran off into the stick and the weeds, chipped up my prop etc etc.
The Bobcat lives to try again!
So before I do this again I need to figure out what the deal is and I want to hear your opinions.
I have run the tar out of this system on the ground and it makes full power, pick it up nose high, shake it around, upside down it still makes full power but it's crapping out and going rich in the air.
Top end is set slightly rich using the pinch test.
Only answer I can come up with is that the tower motor (in comparison with all my other two strokes) exhause outlet is pointed almost straight back (which in this case means directly into the on-comming airstream). So my theory is the air rushing into the exhaust is over-pressurizing the fuel tank causing the engine to run rich at flying speed???
My plan is to try a dubro exhaust deflector which will get the exhaust at least perpendicular to the on-comming air any thoughts?
Now here is where the story gets interesting: After three weeks of either "honey I must work all weekend you'll need to watch the kids" or too much wind, finally Saturday the wife gets off a little bit early and hurries home.
Truck is all loaded, did I forget anything, oh well too bad, I make a flying trip (no pun intended) to the flying field at 3 pm.
(Now I broke this engine in by a process of leaning and richining and I only decided to fly it because the engine broke in to the point that it insisted that I lean the low end needle to get it to start reliably and it would get "up on the pipe" quite nicely
.)Arrive at field 3:25 "come on son help me unload we don't have much time", get unloaded and I make one flight with my fun fly airplane to knock the dust off.
Fuel up the Bobcat, fuss with fine tuning the low end for 10-15 minutes, make a few dry runs...everything checks out, "I may really hafto do this".
Top off fuel tank....out on the runway...full power.....nose wheel turns and I give the Bobcat its first badge of honor a scraped wing tip.
Ciricle around "ok I know shes gonna go left a little on takeoff".....full throttle almost to peak and then it levels off...."crap too far to stop now or its ditch in the desert" I stay on the runway as long as possible pull back on the stick and she rises into the air reluctantly.
(At this point I thought there was no way I was not going to turn my ARF back into a balsa kit.)
Ok well the engine is running very very rich but it's running (this is a good thing I think to myself) and I begin to realize I don't have enough elevator to gain altitude very fast, swtich to high rates "ahh thats better". I and the Bobcat continue to fly at full throttle "feeling like it could fall from the air at any moment" and I get it trimmed out "whew that was scary" and just then I realize I hafto land a plane that might not make a go around.........
The Bobcat feels like it crawling around the sky just waiting for an excuse to commit suicide, but I steady my nerves make a few fly bys a couple of rolls and test out the stall parameters. (she would not turn at this speed without tip stalling). "holy batcrap catman" I think to myself.
Well on one particular turn comming back to the flight line I realize "hey I'm pretty low...this it it now or never.....LANDING!!!!!"
Well I got her down and gave her another battle scar you guessed it I scraped the other wing tip, ran off into the stick and the weeds, chipped up my prop etc etc.
The Bobcat lives to try again!
So before I do this again I need to figure out what the deal is and I want to hear your opinions.
I have run the tar out of this system on the ground and it makes full power, pick it up nose high, shake it around, upside down it still makes full power but it's crapping out and going rich in the air.
Top end is set slightly rich using the pinch test.
Only answer I can come up with is that the tower motor (in comparison with all my other two strokes) exhause outlet is pointed almost straight back (which in this case means directly into the on-comming airstream). So my theory is the air rushing into the exhaust is over-pressurizing the fuel tank causing the engine to run rich at flying speed???
My plan is to try a dubro exhaust deflector which will get the exhaust at least perpendicular to the on-comming air any thoughts?
12-11-2006 | 07:12 PM
#3
Senior Member
RE: Have you ever hear of this?
Pushers don't get any air cooling on the ground. Perhaps it's overheating? Also, make sure the clunk is at least 3/8" away from the back of the tank. It it's too close, it will starve upon acceleration. And...if you have the tank mounted so the clunk is forward and the cap is rearward, switch it around.
Dr.1
Dr.1
12-11-2006 | 07:48 PM
#4
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RE: Have you ever hear of this?
ORIGINAL: AGR413
I recently built and maidened my Nitro Planes Bobcat-50. This is a pusher configuration with a Tower Hobbies .75 turning a 12x6P (pusher) Zinger.
Now here is where the story gets interesting: After three weeks of either "honey I must work all weekend you'll need to watch the kids" or too much wind, finally Saturday the wife gets off a little bit early and hurries home.
Truck is all loaded, did I forget anything, oh well too bad, I make a flying trip (no pun intended) to the flying field at 3 pm.
(Now I broke this engine in by a process of leaning and richining and I only decided to fly it because the engine broke in to the point that it insisted that I lean the low end needle to get it to start reliably and it would get "up on the pipe" quite nicely.)
Arrive at field 3:25 "come on son help me unload we don't have much time", get unloaded and I make one flight with my fun fly airplane to knock the dust off.
Fuel up the Bobcat, fuss with fine tuning the low end for 10-15 minutes, make a few dry runs...everything checks out, "I may really hafto do this".
Top off fuel tank....out on the runway...full power.....nose wheel turns and I give the Bobcat its first badge of honor a scraped wing tip.
Ciricle around "ok I know shes gonna go left a little on takeoff".....full throttle almost to peak and then it levels off...."crap too far to stop now or its ditch in the desert" I stay on the runway as long as possible pull back on the stick and she rises into the air reluctantly.
(At this point I thought there was no way I was not going to turn my ARF back into a balsa kit.)
Ok well the engine is running very very rich but it's running (this is a good thing I think to myself) and I begin to realize I don't have enough elevator to gain altitude very fast, swtich to high rates "ahh thats better". I and the Bobcat continue to fly at full throttle "feeling like it could fall from the air at any moment" and I get it trimmed out "whew that was scary" and just then I realize I hafto land a plane that might not make a go around.........
The Bobcat feels like it crawling around the sky just waiting for an excuse to commit suicide, but I steady my nerves make a few fly bys a couple of rolls and test out the stall parameters. (she would not turn at this speed without tip stalling). "holy batcrap catman" I think to myself.
Well on one particular turn comming back to the flight line I realize "hey I'm pretty low...this it it now or never.....LANDING!!!!!"
Well I got her down and gave her another battle scar you guessed it I scraped the other wing tip, ran off into the stick and the weeds, chipped up my prop etc etc.
The Bobcat lives to try again!
So before I do this again I need to figure out what the deal is and I want to hear your opinions.
I have run the tar out of this system on the ground and it makes full power, pick it up nose high, shake it around, upside down it still makes full power but it's crapping out and going rich in the air.
Top end is set slightly rich using the pinch test.
Only answer I can come up with is that the tower motor (in comparison with all my other two strokes) exhause outlet is pointed almost straight back (which in this case means directly into the on-comming airstream). So my theory is the air rushing into the exhaust is over-pressurizing the fuel tank causing the engine to run rich at flying speed???
My plan is to try a dubro exhaust deflector which will get the exhaust at least perpendicular to the on-comming air any thoughts?
I recently built and maidened my Nitro Planes Bobcat-50. This is a pusher configuration with a Tower Hobbies .75 turning a 12x6P (pusher) Zinger.
Now here is where the story gets interesting: After three weeks of either "honey I must work all weekend you'll need to watch the kids" or too much wind, finally Saturday the wife gets off a little bit early and hurries home.
Truck is all loaded, did I forget anything, oh well too bad, I make a flying trip (no pun intended) to the flying field at 3 pm.
(Now I broke this engine in by a process of leaning and richining and I only decided to fly it because the engine broke in to the point that it insisted that I lean the low end needle to get it to start reliably and it would get "up on the pipe" quite nicely
.)Arrive at field 3:25 "come on son help me unload we don't have much time", get unloaded and I make one flight with my fun fly airplane to knock the dust off.
Fuel up the Bobcat, fuss with fine tuning the low end for 10-15 minutes, make a few dry runs...everything checks out, "I may really hafto do this".
Top off fuel tank....out on the runway...full power.....nose wheel turns and I give the Bobcat its first badge of honor a scraped wing tip.
Ciricle around "ok I know shes gonna go left a little on takeoff".....full throttle almost to peak and then it levels off...."crap too far to stop now or its ditch in the desert" I stay on the runway as long as possible pull back on the stick and she rises into the air reluctantly.
(At this point I thought there was no way I was not going to turn my ARF back into a balsa kit.)
Ok well the engine is running very very rich but it's running (this is a good thing I think to myself) and I begin to realize I don't have enough elevator to gain altitude very fast, swtich to high rates "ahh thats better". I and the Bobcat continue to fly at full throttle "feeling like it could fall from the air at any moment" and I get it trimmed out "whew that was scary" and just then I realize I hafto land a plane that might not make a go around.........
The Bobcat feels like it crawling around the sky just waiting for an excuse to commit suicide, but I steady my nerves make a few fly bys a couple of rolls and test out the stall parameters. (she would not turn at this speed without tip stalling). "holy batcrap catman" I think to myself.
Well on one particular turn comming back to the flight line I realize "hey I'm pretty low...this it it now or never.....LANDING!!!!!"
Well I got her down and gave her another battle scar you guessed it I scraped the other wing tip, ran off into the stick and the weeds, chipped up my prop etc etc.
The Bobcat lives to try again!
So before I do this again I need to figure out what the deal is and I want to hear your opinions.
I have run the tar out of this system on the ground and it makes full power, pick it up nose high, shake it around, upside down it still makes full power but it's crapping out and going rich in the air.
Top end is set slightly rich using the pinch test.
Only answer I can come up with is that the tower motor (in comparison with all my other two strokes) exhause outlet is pointed almost straight back (which in this case means directly into the on-comming airstream). So my theory is the air rushing into the exhaust is over-pressurizing the fuel tank causing the engine to run rich at flying speed???
My plan is to try a dubro exhaust deflector which will get the exhaust at least perpendicular to the on-comming air any thoughts?
-------------
This type of model flies nose high, even in normal level flight. Your engine is lower than normal, this is tantamount to raising the tank height considerably. This alone can explain the engine going rich. The exhaust pressure is high enough that I doubt that overpressurization of the fuel supply is the problem.
A Cline regulator will probably be the answer.
Try the exhaust deflector. It would be a cheap alternative to a Cline Regulator should it turn out to be enough to solve the problem. Good luck.
Ed Cregger
12-11-2006 | 09:16 PM
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From: Mesa,
AZ
RE: Have you ever hear of this?
ORIGINAL: w8ye
Those two kids are precious.
The whole time I was reading this I kept wondering, did you run the engine with the pusher prop on the ground all that much?
Those two kids are precious.
The whole time I was reading this I kept wondering, did you run the engine with the pusher prop on the ground all that much?
No I performed the breaking and most of the tuning with a tractor prop, only the last fine tuning was performed with the pusher prop on. And that consisted of low end mostly, on and off adjusting the low end. I always monitor head temp and am very careful to not overheat an engine.
DR1,
Check, clunk has free movement and tank is installed stopper forward clunk to the rear.
Ed,
You bet I'll take your thoughts under consideration, I did try everything I could to duplicate every attitude in testing and it never went rich or hickuped.
I may have no choice but to look into a regulator but I hope the deflector will fix it.
I had this thing 2-3 clicks off of peak on the ground and it went SLOBBERING rich in the air. I think it's got to be the air compressing over the wing and creating enough of a barrier on that tiny opening at the end of the muffler to cause the muffler to overpressurize the fuel tank. The real kicker is that once I got it on the ground it would "get up on the pipe" and not appear to be over rich at all.
I have had pretty good luck with glow engines and I had a very experienced teacher to help me. This is the first deal that has really left me scratching my head and overpressurization is the only thing that makes sense to me. However, that by no means..means I am right and I appreciate you guys taking the time to read my posts and try to help.
If I ever get the engine flying right I will finish my review:
http://www.rcuniverse.com/product_gu...65&kit_id=4554
12-11-2006 | 11:05 PM
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From: lancaster,
CA
RE: Have you ever hear of this?
Tank is in front of the powerplant; makes it run rich in climbes, and you'll never have any luck with taxi time on the ground. been there done that. Just fire it up, get him out of the pits now and go. Didn't you consult your ground crew for the important desicions?
12-12-2006 | 01:38 AM
#8
My Feedback: (21)
RE: Have you ever hear of this?
Where is your balance point ? I set my tank up with no clunk....just the pick-up
at the rear of the tank, near the bottom, and the vent in the normal high position.
This plane will be flown like a normal (turbine) Bobcat....circles, rolls, and loops....
....all positive G's....I don't need no stinkin' clunk....
I am going to yank the YS .63FZ....not enough power, and put in a Tower .75. I'll
be using an 11-8 prop....not the wimpy 12-6. [
FBD.
at the rear of the tank, near the bottom, and the vent in the normal high position.
This plane will be flown like a normal (turbine) Bobcat....circles, rolls, and loops....
....all positive G's....I don't need no stinkin' clunk....
I am going to yank the YS .63FZ....not enough power, and put in a Tower .75. I'll
be using an 11-8 prop....not the wimpy 12-6. [
FBD.
12-12-2006 | 02:35 AM
#9
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From: Mesa,
AZ
RE: Have you ever hear of this?
ORIGINAL: Flyboy Dave
Where is your balance point ? I set my tank up with no clunk....just the pick-up
at the rear of the tank, near the bottom, and the vent in the normal high position.
This plane will be flown like a normal (turbine) Bobcat....circles, rolls, and loops....
....all positive G's....I don't need no stinkin' clunk....
I am going to yank the YS .63FZ....not enough power, and put in a Tower .75. I'll
be using an 11-8 prop....not the wimpy 12-6. [
FBD.
Where is your balance point ? I set my tank up with no clunk....just the pick-up
at the rear of the tank, near the bottom, and the vent in the normal high position.
This plane will be flown like a normal (turbine) Bobcat....circles, rolls, and loops....
....all positive G's....I don't need no stinkin' clunk....
I am going to yank the YS .63FZ....not enough power, and put in a Tower .75. I'll
be using an 11-8 prop....not the wimpy 12-6. [
FBD.
Are you pulling my leg? no clunk, I'll bite on that one when I see it...lol.
Hey I tried the 11x8 prop and it does not push near the air the 12x6 does (on the ground that is) I don't know if it would be any better in the air.
I wish you would hurry up you have been talking about slapping in that .75 for a couple of weeks, that way you could figure all this weird stuff out and I could just read the answers and go on my happy way....(sorry I had to)...
Anyway, I have asked this question two different places now and for the moment I'm sticking with my backpressure interference theory.
These engines don't create a whole big bunch of backpressure, so I don't think it would take much to have an effect. If I get really motivated between now and Saturday I'll fire it up in the driveway and direct my aircompressor nozzle at it.
Oh and on the balance point I'm right at 10.3, I'm gonna recheck it with the dubro deflector on there but I don't think it will change much. Even if it does I don't think it will hurt it was not overly sensitive when I flew it. I would just about bet that 10-11 inches will work.
12-12-2006 | 02:40 AM
#10
My Feedback: (21)
RE: Have you ever hear of this?
No....I wasn't kidding about the clunk....think about it.
The Tower muffler needs to be completely sealed to provide maximum pressue to the tank.
There is no baffle in the muffler, and it is a high volume muffler to boot.
I'll get the 75 in there soon....I promise....
FBD.
The Tower muffler needs to be completely sealed to provide maximum pressue to the tank.
There is no baffle in the muffler, and it is a high volume muffler to boot.
I'll get the 75 in there soon....I promise....
FBD.
12-12-2006 | 04:51 AM
#12
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RE: Have you ever hear of this?
These engines don't create a whole big bunch of backpressure, so I don't think it would take much to have an effect. If I get really motivated between now and Saturday I'll fire it up in the driveway and direct my aircompressor nozzle at it.
-----------
You might very well be right about the backpressure from the relative wind increasing the muffler pressure in the fuel system and driving the engine rich. I did not intend to sound dismissive. I just wanted to point out that the engine will be substantially lower than the fuel tank during normal level flight.
Ed Cregger
12-12-2006 | 05:09 AM
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From: Martinsville,
IN
RE: Have you ever hear of this?
There is a plane like that at our field and the owner took a coper pipe and bent it like a horse shoe and clamped the pipe on the muffler tip. It now has rear exhaust for no clean up except for prop.
12-12-2006 | 07:18 AM
#14
Senior Member
RE: Have you ever hear of this?
AGR,
That is the whole caboodle of troubles.
First, a swept wing does not work very well at low subsonic speeds and the swept-back control surfaces are less effective.
As Dr1 wrote, when static; i.e. not flying at full speed, cooling for the engine is marginal at most, since the prop doesn't draw the air straight back, through the engine's cooling fins. A tractor prop will blow the air that way in a 'conventional' plane.
The tank is reversed and mounting it with the clunk at the back will lead to looong fuel lines... Or, if you prefer, mounting it with the clunk forward and have intermittent fuel feed... And the engine goes rich when you pick up the nose and lean, when you pitch it down.
And since the prop blows the air behind all the control surfaces, the amount of control you have at low speed is nil, like in a jet powered (or ducted fan jet) plane. Only at speed do your plane's control surfaces do anything.
With a conventional plane, you got yaw, pitch and (with strip ailerons, some) roll control, even when the plane is standing still (as most 3-D planes fly).
This model would not be my choice, unless I wanted to use a turbine in it and to fly it very briskly.
That is the whole caboodle of troubles.
First, a swept wing does not work very well at low subsonic speeds and the swept-back control surfaces are less effective.
As Dr1 wrote, when static; i.e. not flying at full speed, cooling for the engine is marginal at most, since the prop doesn't draw the air straight back, through the engine's cooling fins. A tractor prop will blow the air that way in a 'conventional' plane.
The tank is reversed and mounting it with the clunk at the back will lead to looong fuel lines... Or, if you prefer, mounting it with the clunk forward and have intermittent fuel feed... And the engine goes rich when you pick up the nose and lean, when you pitch it down.
And since the prop blows the air behind all the control surfaces, the amount of control you have at low speed is nil, like in a jet powered (or ducted fan jet) plane. Only at speed do your plane's control surfaces do anything.
With a conventional plane, you got yaw, pitch and (with strip ailerons, some) roll control, even when the plane is standing still (as most 3-D planes fly).
This model would not be my choice, unless I wanted to use a turbine in it and to fly it very briskly.
12-12-2006 | 10:01 AM
#15
RE: Have you ever hear of this?
Your theory has some basis. A pitot tube and a pressure gauge is used to measure an airplanes airspeed. The incoming ram air pressurizes the Pitot tube and the pressure gage is calibrated to the correct conversion. That conversion for air velocity is P = (V/4005) ^2 for the density of air, a pressure measurement in inches of water, and velocity in Feet per Minute (FPM). Assuming that your plane was flying around 60 MPH then that is 5280 FPM. So crunching the numbers I get 1.74" of water or about 2" of fuel. This is not that significant and though noticeable I don't think it would be enough to richen it up to a dangerous point. From reading your startup procedure did you only fill the tank partially? If so that would add another inch or two of fuel head and 4" of fuel head is becoming significant.
Now that you know that your plane can tip stall, then you know you should add rudder on turns. This keeps the angle of attack the same on both tips so that it will stall straight. If uncomfortable using rudder then you can program them to turn with aileron, then add just a touch manually in steep turns.
Now that you know that your plane can tip stall, then you know you should add rudder on turns. This keeps the angle of attack the same on both tips so that it will stall straight. If uncomfortable using rudder then you can program them to turn with aileron, then add just a touch manually in steep turns.
12-12-2006 | 11:15 AM
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From: Mesa,
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RE: Have you ever hear of this?
Dave,
Once I get this rich in the air thing worked out I will try the 11x8P I have two of them. I'm gonna have a hard making myself do it until I get this RPM thing whipped.
Speedster,
Copper pipe got it another option thanks.
Ed,
No worries I apreciated your comments and in no way felt your comments were dismissive. I usually have really good luck with all my glow engines and planes due to several very nice, very experienced people who took the time to help me when I asked for help at the time I was expanding from electric only to glow. You seem like you really know your stuff and are willing to help when people ask so don't hold back.
In general,
I think I accidentaly implied that I thought the plane itself flew poorly which is not the case. This plane flies great, I did end up using rudder to asist in the turns and I blame all of the tip stall stuff on the low speed due to the engine not producing enough revs. Actually I am highly impressed that the plane allowed me to get away with what I did. This plane is a good flyer!
This plane would be great for a small turbine but I assure you that once I get the rpm deal figgured out this plane will shred with a tower .75. I don't believe 100+ mph is going to be a problem even with all that wire and rubber hanging off the bottom..."I wonder if I could hand launch this plane"....hmmmmmmm.....
Thanks for all the input!
Once I get this rich in the air thing worked out I will try the 11x8P I have two of them. I'm gonna have a hard making myself do it until I get this RPM thing whipped.
Speedster,
Copper pipe got it another option thanks.
Ed,
No worries I apreciated your comments and in no way felt your comments were dismissive. I usually have really good luck with all my glow engines and planes due to several very nice, very experienced people who took the time to help me when I asked for help at the time I was expanding from electric only to glow. You seem like you really know your stuff and are willing to help when people ask so don't hold back.
In general,
I think I accidentaly implied that I thought the plane itself flew poorly which is not the case. This plane flies great, I did end up using rudder to asist in the turns and I blame all of the tip stall stuff on the low speed due to the engine not producing enough revs. Actually I am highly impressed that the plane allowed me to get away with what I did. This plane is a good flyer!
This plane would be great for a small turbine but I assure you that once I get the rpm deal figgured out this plane will shred with a tower .75. I don't believe 100+ mph is going to be a problem even with all that wire and rubber hanging off the bottom..."I wonder if I could hand launch this plane"....hmmmmmmm.....
Thanks for all the input!
12-12-2006 | 11:55 AM
#17
RE: Have you ever hear of this?
Just trying to be helpful. Some jump to such planes with less experiance. You could try a uniflow tank. That would be more tolerant of high angle of attach + increased muffler pressure. With a pusher configuration a simple tounge muffler should work. Or cap the exhaust cut a hole in the side and route a new stinger out the side and toward the back of the cheap Tower muffler. That way you can get that possibility off the map and keep oil of the plane at the same time.
12-12-2006 | 12:55 PM
#18
RE: Have you ever hear of this?
AGR,
You may want to try a fuel pump. I have a Tower 75 in a BUSA Enforcer. Don't know if you've seen one but it is a delta wing pusher weighing about 6 lbs.
I use the Perry P30 pump because I was concerned about the long fuel lines, so no muffler pressure issues. I'm also using a Mac's Products exhaust deflector which may also help.
I'm using an APC 11x7. Who makes an 11x8 pusher?
Patrick
You may want to try a fuel pump. I have a Tower 75 in a BUSA Enforcer. Don't know if you've seen one but it is a delta wing pusher weighing about 6 lbs.
I use the Perry P30 pump because I was concerned about the long fuel lines, so no muffler pressure issues. I'm also using a Mac's Products exhaust deflector which may also help.
I'm using an APC 11x7. Who makes an 11x8 pusher?
Patrick
12-12-2006 | 02:44 PM
#22
RE: Have you ever hear of this?
I doubt this would normally be a problem, but I think these tuned mufflers tend to have low muffler pressure so 2" of pressure may be significant. One could also make a deflector which shields the exhaust from the oncoming air, but it may make the airplane messier.
12-12-2006 | 03:02 PM
#23
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From: Mesa,
AZ
RE: Have you ever hear of this?
I'm going to run the compressed air test...we shall see....
Oh and you know what I have a wind meter I can find the distance from the nozzle that simulates say 20, 40 and 60 mph etc etc.
Oh and you know what I have a wind meter I can find the distance from the nozzle that simulates say 20, 40 and 60 mph etc etc.
12-13-2006 | 12:48 AM
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From: lancaster,
CA
RE: Have you ever hear of this?
With the tank in front of the engine, you get free presure fom gravity and inertia in a climb because the clunk is facing to the rear of the tank just as in a conventional setup; You could lean the top end needle some and play with him to get it right. I have never played with Tower engines so I dont know the relationship between the high and low end needles. The air hitting the muffler facing forward is nothing to be concerned with.
