The thread on design (Al R., et.al)

differences was getting a "little" long, and I hope you don't mind a newer iteration of it. No offense to the Big Lizard!

Since I have only had 3 of what I would call PAMPA planes (SV-11, Inline Junar, Geo Juno-'Saturn' redrawn outlines) over the last ten years, I have a couple legitimate (to me) questions:

1. Trivial Pursuit/Star Gazer; what if this plane is built 54-56 oz. how would this affect the performance? (sounds like they fly about 10 oz. heavier)

2. Same for a Patternmaster (certain people say they can be built too light)

3. I am using a 51 pipe in my Geo Juno; what advantage would I expect, if any, should I go to a 61/pipe? (plane is 54 oz)

4. More explanation of "Large" propeller theory as discussed in other thread. Turn rate effects vs. ?????

We are building one of Al's Bearcats (older published one, II??) and have it set up for a ST 51. What is a resonable weight to shoot for?
First foray into the scale stunt realm! A Mustang is next.

Lots more questions, but not enough knowledge to ask them.
Bill <><

Thanks guys, it's all right. This ol' Redneck won't forget.
Over 4 hours, no repiles.
Bill

Bill,
(1) I think David's airplane is 56 ounces and flies very well always had crisp and clean corners. Ted's T/P also flies great so that should tell you that within reason weight is not much of a problem.
(2) I never heard that a Patternmaster could be built too light. Maybe that would be a problem in the high forties up highly unlikely you could build one at that weight.
(3) Yes the PA .61 does have more power and that is a good thing. However, the props are not that much bigger so it is doubtful you would be able to tell the difference. The one thing I never liked was that the PA 51's would run backwards and scare the heck out of ya.
(4) My opinion, this get way more press than it should. It is an easy matter to trim the model so it is not a factor. I have switched from three blade to a larger two blade props many times with very little trimming changes needed if at all.
(5) Ask Keith he has been flying one for a few years now but I think he told me it 52 ounces but I could be wrong. It still flies very well and Keith does a good job flying it as well.

Later

Hi Mikey,
I had a thought that Ted's plane was a little heavier than David's.
I launched Ted on some practice flights at the '96 NATS, but it didn't feel THAT heavy.

Windy had made comment at one time about the PM needing a certain "weight"...... can't remember exactly what, or on which video.

As to the 51/61 on pipe, from your, and the other's comments, the difference probably wouldn't make enough "difference". I am "used to" the .51 right now, so it will probably be best to just stick with that combo. (??)

Thanks, buddy, and I still thank you for helping out with Aaron at the '96 NATS!

Bill <><

>1. Trivial Pursuit/Star Gazer; what if this plane is built
>54-56 oz. how would this affect the performance? (sounds
>like they fly about 10 oz. heavier)

Hard to say in the cae of the TP. It has such unique characteristics in the way it appears to behave, I am not sure what changes would be necessary to fly at a lighter wing loading.

>2. Same for a Patternmaster (certain people say they can be
>built too light)

In the case of the Patternmaster I think you will find that one of two things would need to happen, either the nose would need to be shortened to move the CG more aft (or a heavier engine installed, or the flaps reduced in size. The wing is so large that a "rise up" tendency would most likely result. The other cure would be to dial out flap vs. elevator.

>3. I am using a 51 pipe in my Geo Juno; what advantage would
>I expect, if any, should I go to a 61/pipe? (plane is 54 oz)

You could run in a deeper 4 cycle on the same prop. You will also burn more fuel in that same deep 4 cycle.

>4. More explanation of "Large" propeller theory as discussed
>in other thread. Turn rate effects vs. ?????

On 10" noses I think the prop radius is super critical. I am not so sure if that is true down at 7" though. Larger props "typically" result in larger radius corners, all things being equal.

>We are building one of Al's Bearcats (older published one,
>II??) and have it set up for a ST 51. What is a resonable
>weight to shoot for?
>First foray into the scale stunt realm! A Mustang is next.

I am sure Al can tell you here.

Bill,

The T&L ST .51 will haul a plane of 58-59 ounces with ease.

A .61 instead of a .51 in a 54 ounce airplane, don't know, call
Billy up and ask him if a PA .61 would be a good choice. I think
his P-47 is somewhere in that range, but it has that 62" higher aspect Geo/Bolt wing in it.

>Bill,
>
>The T&L ST .51 will haul a plane of 58-59 ounces with ease.
>
>A .61 instead of a .51 in a 54 ounce airplane, don't know,
>call
>Billy up and ask him if a PA .61 would be a good choice. I
>think
>his P-47 is somewhere in that range, but it has that 62"
>higher aspect Geo/Bolt wing in it.
>
>Jim Pollock

Thanks Jim,

Actually the T&L 51 will pull a 64 oz. airplane with ease, witness my first SV-11.

I think the PA 51 will stay in the Geo Juno.. I was flying it with an OS 40 VF at Brodak's. Gonna wait on the .61 until I get my new plane done. It will have the Geo Bolt wing.

See ya soon,
Bill <><

Perhaps Paul or Howard will respond. I know that Paul built an extremely light Impact and had some problems. He has commented that there is an ideal weight for the Impact and that it's not neccessarily the lightest it can be built.

Sorry Brad, but I have to disagree with you on a few points.

If indeed you built a Super lightweight Patternmaster the only change needed would be to change the control ratio (more elevator than flap) and maybe shorten the nose for balancing only. A good example is my Super Aries, 700 square inch wing, 18" tail moment, 21% flaps, and only 49 ounces. Not far form the same numbers and needed a 2 to 1 control ratio.

The PA .40, .51, .61, and 65 all burn about the same amount of fuel. The .65 burns about 6.25 ounces as compared to the .40 at 5.75 (10% nitro). All very close.

I have flown the G Force (10.5" nose) with props ranging from 10.75" to 14" with very little trim changes needed. The handle spacing was opened up for the larger prop. Now if we went from a 12" prop to a 16" prop we might see a big difference but at the size prop we are all using it is just not a big deal.

>Sorry Brad, but I have to disagree with you on a few points.
>
>If indeed you built a Super lightweight Patternmaster the
>only change needed would be to change the control ratio
>(more elevator than flap) and maybe shorten the nose for
>balancing only. A good example is my Super Aries, 700
>square inch wing, 18" tail moment, 21% flaps, and only 49
>ounces. Not far form the same numbers and needed a 2 to 1
>control ratio.

I thought that was what I said.

>The PA .40, .51, .61, and 65 all burn about the same amount
>of fuel. The .65 burns about 6.25 ounces as compared to the
>.40 at 5.75 (10% nitro). All very close.

Doug, Bob, Mike Scott all burn nearly 8 oz in there .65's.

I think Werwage burns more than that, he uses a 10 oz clunk tank in his big planes I am pretty sure.

These are just my measuring sticks.

>I have flown the G Force (10.5" nose) with props ranging
>from 10.75" to 14" with very little trim changes needed.
>The handle spacing was opened up for the larger prop.

Never had that kind of luck.

>>The PA .40, .51, .61, and 65 all burn about the same amount
>>of fuel. The .65 burns about 6.25 ounces as compared to the
>>.40 at 5.75 (10% nitro). All very close.
>
>Doug, Bob, Mike Scott all burn nearly 8 oz in there .65's.
>
>I think Werwage burns more than that, he uses a 10 oz clunk
>tank in his big planes I am pretty sure.
>
>These are just my measuring sticks.

A lot will depend on how you set them up. If you use large venturis and then run them in a deep 4-cycle, you will burn more fuel. I think Matt has a 6 1/2 ounce tank on his, but uses less than 6 ounces. That's on a 61 and a number 12 or number 10 venturi. And he is also using a large prop.

>>I have flown the G Force (10.5" nose) with props ranging
>>from 10.75" to 14" with very little trim changes needed.
>>The handle spacing was opened up for the larger prop.
>
>Never had that kind of luck.

Again Matt is running large probs but not seeing a lot of problems caused by the prop. He is looking to go bigger. If the prop were causing problems, he would certainly back up. He is quite sensitive to trim changes and effects.

Bill,

As for your questions about the Bearcat, I'll try to offer some clarification. The original Bearcat I had basically a Nobler wing which didn't have enough flap area after I tapered the trailing edge. It did have dihedral. After about 900 flights and a good deal of competition success, I decided to modify the wing for better performance. I removed the small flaps, gutted the wing trailing edge and moved the hinge line forward about an inch at the wing tips. This trade of wing area for flap area significantly increased the lift available for tightening the turns. This is the last airplane I ever built with an open bay wing. This airplane was 2nd at the 1969 NATs behind Lampionie before the modification to the wing.

I never built a Bearcat II. It was basically the original Bearcat with the modified wing, and said as much in the article. The airfoil was slightly improved. This was the magazine plans.

The Bearcat III was a major upgrade of the Bearcat II. It had a molded fuselage which decreased the weight and rounded the fuselage shapes. The landing gear, tail surfaces on fuselage outline remained the same. The wing was seriously improved by trading even more wing area for flap area and used a better airfoil based on airfoil tests. The wing was removable. the tank was also removable through the open fuselage with the wing removed. It was a very competitive air pane which placed 2nd at the 1970 NATs just a couple of points behind Keith.

The original Bearcats all flew with ST 46s and flew OK as long as the weight stayed around 53 ozs. The "new" Bearcat III which is the airplane in the PAMPA plans and weighs 57ozs with a PA 61. It is also a very pleasant flying airplane and fully competitive with 60 size engines. It is classic legal as it duplicates the 1969 construction of the original Bearcat III.

For what its worth, the Bearcat I and III depict a specific Bearcat which had the Falcon paint job and small wing fences. Because they were on the prototype for the model, I use the wing fences also on the model. The fences may actually have some positive effect on the ability of the 60 powered heavier airplane to turn as well as the lighter airplanes with smaller engines. All the Bearcats were very pleqsant to fly and won their share of the hardware.

Hope this helps.

Thanks Al,

It Does help clarify the situation. So much so that I will have to get the PAMPA plans and do a III! Aaron is building the published one, and it looks good so far. Wing, fuselage, stab and vertical fin are done. We are molding the top and bottom "blocks" from 3/32. It will use a "square head" ST 51.

Thanks for the comments!
Bill <><