For Brett Buck...

Hey Brett there was some talk on the 15cc thread about Paul and how he was running his setup "wrong" in the eyes of some.

Could you please elaborate on what he was doing to be considered wrong, besides the small prop? More or less the theory behind his setup.

Thanks

LAST EDITED ON Nov-18-03 AT 12:18 PM (CST)
 
>Hey Brett there was some talk on the 15cc thread about Paul
>and how he was running his setup "wrong" in the eyes of
>some.

Let me emphasize that the comments I heard to this effect *dumbfounded* me. I simply didn't know how to respond. It was like someone suddenly started speaking Aramaic to me in the middle of a sentence.

>Could you please elaborate on what he was doing to be
>considered wrong, besides the small prop? More or less the
>theory behind his setup.

Might just want to ask Paul. I don't think there's a lot of value to be had in discussing what was supposedly "wrong" about it, given the absurd underlying premise. when you can instead find out what's right about it.

LAST EDITED ON Nov-18-03 AT 12:35 PM (CST)
 
> Might just want to ask Paul. I don't think there's a lot
>of value to be had in discussing what was supposedly "wrong"
>about it, given the absurd underlying premise.

Of course, consider the source. Some "guy" telling PAUL WALKER what HE DOES NOT LIKE ABOUT THE SETUP THAT WHIPPED HIS BUTT!

I am sure PAul has had to deal with similar comments made about the 4 stroke (and the B-17).

Some guys with their comments. It really has no reflection on Paul, its really a reflection of the guy making the comments. Most people who make unsolicited negative comments (just in general) have a lot of self esteem issues...

I have met a few of those guys in my time. They are very quick to tell you their opinion of your stuff. Many times these comments are negative simply because saying anything positive would reflect negatively (internally) on the person who said it. So, in a highly competitive environment, to complement someone is to admit your inferiority.

It is really pretty pathetic. I don't want to be that guy.

I just put this out there to you because you have been involved and would know pretty much what was up..??

>
>Could you please elaborate on what he was doing to be
>considered wrong, besides the small prop? More or less the
>theory behind his setup.
>
>Thanks

If you could fill me in on the "what's wrong", I could comment on that.

Ah yes the man himself makes an appearance.

What was different about the way you ran your VF system compared those who were the majority of the day?

I was busy crashing in inverted flight in those days...

>Ah yes the man himself makes an appearance.
>
>What was different about the way you ran your VF system
>compared those who were the majority of the day?
>
>I was busy crashing in inverted flight in those days...

Ah...Finally I have a few minutes to respond....

There were basically 3 things that I did different than others (not including Brett). 1) 11.3" dia prop, 2)0.275" dia venturi, and 3) 18.75" long pipe.

Why was I using these numbers?

1) I can't begin to tell you how many props were tried (and ruined in the process) to determine the "best" prop for that airplane. There were MANY compromises along the way. It should be obvious that if someone else were making decisions on these compromises that their setup would be different. I chose the 11.3" diameter to provide (as Mustang noted already) an easy turn with virtually no stick force increase so that I could "feel" exactly what the plane was feeling. Yes, it reduced the overhead line tension (please..no further discussion on large props here)and the vertical performance in the hourglass, but that was part of the trade. I was totally un-willing to sacrifice ANY (heck, ANY^4) performance in the square eight. After selecting this prop, other variables were checked against it. They were heat, humudity, and power. In the midwest NATS, it was generally hotter than Seattle (well duh), but even there, the 11.3" prop worked the best. In years past, I tried the OS 46VF as a stronger replacemant for the 40. Yes it made more power, BUT, even with the exact same prop, the corners slowed down and had more stick force compared to the 40. I stuck with the 40. The PA 40 used this same prop as well. Also, I couldn't get the PA 51 or 61 to run on this prop to my satisfaction (they wanted to be loaded more). I was WRONG because everyone else used more diameter in their setups.

2) The 275 venturi came from tests done in 1990 in the LA area. Anything larger caused variations in run quality between 60 degree weather and 100 degree weather. The venturi size was played with until it worked exactly the same in hot versus cold. The "beauty" of the LA area was that I could get these differences in temperatur in a single day within a few hours of each other (usually in June or July). I would fly at "Whitter Narrows" in the morning and go the "Sepulveda Basin" just after lunch. I have tried using larger venturies in the mid west in 100 degree humid air, and I go back to the 275 every time. Once again, I was wrong because everyone else was using a bigger venturi for more power, and theirs worked, thus mine couldn't be right.

3) The 18.5 to 18.75 pipe length worked extreemly well with the OS 40 and the Impact. It still had a power up capability, and a braking capability, but much less pronounced that the shorter (16.5") pipe lengths. Much the same as in 1 above, this allowed tighter corners as I wasn't fighting the power up in the corners (similar to the 46).

The combination of these 3 variables worked well in many different conditions. Still dead (the deader the better) air was my friend. This set-up produced a minimum of "wake" that would send a plane into the ground in a wink. The 1995 Team Trials were a fine example of that. It also flew in the wind well. The 1992 Nats on Friday was a good example, as well as the 1994 NATS finals (right Bob?).

This setup is fairly close to where Bob Hunt is trying to go now. Less line tension, a light plane, and finger tip feel your way through the patters to "feel" everything. Bob IS doing it with a smaller and lighter plane than I did, and the concept is much the same. (btw...Good job at the TT's Bob).

In summary, I did it wrong (according to many "experts") but my superior piloting skills were the difference. Yup...Just keep thinking that guys!

Excuse me while I dust of the "Total Impact" and it's 3 NAT's winning trophies, it's winning Team Trials trophy, and it's winning World Champs trophy. I might want to bring it out again just to show everybody that "size doesn't matter". Of course I'm talking about the prop!! I don't believe I am a better pilot than most of my competition. I do posess the ability to get the most out of my equipment for any given condition, and this I believe contributes significantly to my success. So if I'm not a better pilot, and with a few wins I guess luck is not the issue, then I must be doing something else right. That's my assessment, even though I am doing it wrong!

Note 1): One of my favorite NAT's wins was in 1998. The finals were in near 100 degree heat, and humidity, the air was virtually still, and my wimpy little 40 with it's toothpick prop was up against those monster 60's. I had no chance! Somehow....It powered through those conditions and won.

Note 2): One of my "other" favorite NAT's wins was in 1994. Won by 1/2 a point!!

Paul,

This is simply a great post.

It has taken some time to understand fully what you have been trying to achieve, even though you pretty much explained it to me more than once.

Basically, everything we do in this event is a compromise. To achieve strengths in one area typically weakens other areas THIS APPEARS TO ME TO BE A UNIVERSAL CONSTANT.

The smart man goes where the points are, I see that now. Without some strategy, you are simply chasing yor tail.

Everyone should read Paul's explanation over and over again until they get it.

Thanks for all your help,
Brad

>>I was busy crashing in inverted flight in those days...
>
>Ah...Finally I have a few minutes to respond....
>
>There were basically 3 things that I did different than
>others (not including Brett).

It took me a while to clue in to it, too, and it started out as simply copying it and trying to see how it worked. Then, the light finally dawned...

Of course, I didn't have the rest of the package (practice flights, competitive drive, basic physical skills) - thus my mediocre and wildly inconsistent showings.


Brett

> It took me a while to clue in to it, too, and it started
>out as simply copying it and trying to see how it worked.
>Then, the light finally dawned...
>
> Of course, I didn't have the rest of the package (practice
>flights, competitive drive, basic physical skills) - thus my
>mediocre and wildly inconsistent showings.
>
>
> Brett

Did you ever consider teaming up with someone who practices, has a competitive nature, required basic physical skills, and who likes you, believes "Brett Buck" is your real name?

Ooops, those last two requirements pretty much answer my question.

Thanks Paul! Very enlightening. I was pretty lost when the comments started flying because I'm not a Stunt flier, and haven't been following these discussions over the years.

Can you elaborate further on whether your current setup (4 stroke) differs from the earlier setup, especially in terms of what you're trying to achieve, and if it differs very much from other peoples' 4 stroke setups?

(Perhaps the B-17 shouldn't be mentioned here.. though I'm curious as to how it handled in the turns in comparison to the .40VF airplane.. )

>(Perhaps the B-17 shouldn't be mentioned here.. though I'm
>curious as to how it handled in the turns in comparison to
>the .40VF airplane.. )

Pretty much the same.

LAST EDITED ON Nov-20-03 AT 02:35 PM (CST)
 

>Can you elaborate further on whether your current setup (4
>stroke) differs from the earlier setup, especially in terms
>of what you're trying to achieve, and if it differs very
>much from other peoples' 4 stroke setups?
>
I have gone to the four stroke setup for one purpose only. That is for it to be used at the W.C's in front of the international judges. One thing I have noticed is that sound very clearly impacts the minds impression of how fast a plane is flying. So, this is an attempt to have the impression of the plane flying slower with a more "mellow" sound. I have been using them for 3 years now, and am slowly getting the bugs worked out. One side effect (and I admit it was unexpected) that has come from the use of these engines is the repeatability of quality patterns. Once the aircrafts trim is set, the quality patterns are much more consistent that what I found with the two strokes. I might venture a quess that the CG is farther forward, and still has an adequate corner, and my aging reflexes are more attuned to it. Right or wrong, I feel that I can consistently fly at a higher level with that setup. (Item for discussion: I believe under absolute perfect conditions that a piped two stroke can perform better than a four stroke when the two stroke is in absolute perfect trim. The problem is finding those two different equations intersection point, and having that intersection point in time being the finals of the NAT's or World Champs. This can be very difficult to find, and it is TOTALLY out of the hands of the pilot because one of the conditions was perfect weather. Are you willing to wait around long enough for those two events to collide, or would you rather have a plane that will perform "very well" in all conditions, or one that possibly will perform "very,very well" if the conditions are perfect? I feel the four stroke provides me a wider performance band of very good capability, that I will choose it for the W.C's!)

Now, what's changed from earlier, or what's different than others? I don't know that there is much of a data base to base this on. Brad has been very helpful in my efforts with four strokes. What's Different:
1) I now use a standard vented clunk tank. No more uniflow.
2) Fuel: I use YS/Saito 20/20. Used to use some castor, but no longer. Ran all last season without one drop of castor in the 72. Still like new.
3) Handle: Changed back to the handles like I used on the Impact. Started with the "bar" handle on the first Mustang, and after the NAT's tried my "E-Z Just, no cable" handle. Really woke up the plane, and made the corners, even on the big four stroke, much easier and quicker. Have used that type ever since.
4) Props: Still use the same 13 * 5 3 blade Bolly I have used for years now. Have tried others, but this seems the best compromise (see Impact discussion above).
5) Mixture: About 2 or 3 "clicks" off dead lean. Nothing richer.
6) Venturi: UHP .265
7) Ground rpm....Varies by temperature and barometric pressure. Somewhere around 10,000 rpm ready to go. And go it does when released!

If there are more questions, please ask.

>l use the same 13 * 5 3 blade Bolly I have
>used for years now. Have tried others, but this seems the
>best compromise (see Impact discussion above).

I'm curious- did lower-pitched props increase the randomness/decrease the repeatability? I've seen some examples where people (well, Uncle Jimby) were down to close to 4.0 on the 56, and it seemed to be able to spin it, albiet not happily.

I used my pipe prop BE 12x3.5 3blade UCT on Os Max .52 4C. It worked really well, but I feel it's power more depends on conditions (pressure, humidity, temperature). And I had also problems with starting - it really likes to start backward.

> I'm curious- did lower-pitched props increase the
>randomness/decrease the repeatability? I've seen some
>examples where people (well, Uncle Jimby) were down to close
>to 4.0 on the 56, and it seemed to be able to spin it,
>albiet not happily.

Currently, I am running the Eather 13 x 3.75 3 blade (stock).

My takeoff is a little under 11,000 (10,700 norm).

The Eather needs less pitch than the Bolly.

Uncle Jimby might have been fine if had opened the venturi to compensate, I suspect he did not (this is especially true on pressure).

I would say my runs are extremely consistent. Maybe as good as ever. I never had any problems being consistent. I have my issues I am dealing with, but nothing any different than anyone else. I suspect the next generation 4 stroke setup will be pretty much in the same pitch and RPM range as most piped stunt engines (no special props needed, yaaah).

Just FYI.

> I have
>my issues I am dealing with, but nothing any different than
>anyone else. I suspect the next generation 4 stroke setup
>will be pretty much in the same pitch and RPM range as most
>piped stunt engines

Does it punch out to the ends of the square 8 OK in the wind? That's sort of what sets the lower limit of pitch on piped engines. Or at least for piped engines set up to not brake back and forth. Having it 4-2 in the square 8 may allow less pitch, but causes other problems that I seem to be really sensitive to.

I ran the VF with as low as a 12-3.25 Bolly, but then I learned better. It sure never had any problem with vertical performance that way!

> Does it punch out to the ends of the square 8 OK in the
>wind? That's sort of what sets the lower limit of pitch on
>piped engines. Or at least for piped engines set up to not
>brake back and forth. Having it 4-2 in the square 8 may
>allow less pitch, but causes other problems that I seem to
>be really sensitive to.

I think the 4 cycle is a little different animal in that there is no "full tilt" 2 stroke mode to fall back on, so if the speed drops it can be hard to get it back fast.

I would say that 3.75 to 4.25 pitch will be the norm (this is really no different than a RO Jett 65--in fact Bill Wilson and I use the same props).

You appear to be right about one other thing I forgot to mention. If you drtop the pitch (on my rig) to 3.5 the power regulation goes haywire. I think the engine is too far out to the right on the curve. I think the sweet "stunt spot" on the curve is just past peak.

Of course pitch is relative to nitro. Raise the nitro drop the pitch. I have been running 3.75 with 15% nitro. If I stay with 15% I would probaly go to 4.0 or so. If I stay with 3.75 I would go back to 20% nitro.

Paul Thank you. HHHAAA ONE THING. Fuel? What did you try and what was the good stuff. And on the prop, UC or flat back? Just would like to know, so I can put it(notes) away with My OS-40 VF.

scott(great post)Riese

>Paul Thank you. HHHAAA ONE THING. Fuel? What did you try and
>what was the good stuff. And on the prop, UC or flat back?
>Just would like to know, so I can put it(notes) away with My
>OS-40 VF.
>
>scott(great post)Riese

Thanks Scott.

Fuel. 10% Vitamin N 20% slippery stuff.

Sound flippant, but it's not. Most any fuel works in this engine, as long as it is "fresh". And of course, no water in the fuel. That's about the limit. I have tried most of the extremes:
10% N, 20% all castor. Works just fine!
10% N, 10% C, 10% syn oil. Works just fine!
10% N, 5% C, 15% syn oil. Works just fine!
Manufacturers: Powermaster, FHS (Red Maxx), Sig, and others I'm too embarassed to mention. I have even used 6 year old, half used out of the jug with perfect results. Just don't let the water in, or the nitro out.

Prop. "THE" prop is: Bolly 11.75 8 4.25. It is a "flatback" prop. Cut to 11.3" dia, and re-pitch to 4.0 to 4.25 (your preference). Start with the prop mentioned. Not others "bent" to that shape.

Thanks Paul.

See you in APRIL here in Portland

Paul,

Thanks for the reply. You rule!

Brad is right all the way.(did I just say Brad is right??)

EVERYONE PLEASE READ THAT POST AND GET IT IN YOUR HEAD UNTIL IT IS SECOND NATURE!!!

I think sometimes I am trying for that very thing. I just didnt know it. I dont have real light tension but lighter than most who run the 65 by a good amount but it just feels so active in every part of the pattern and I can really tell what is going on. Even with a bar handle...

Thanks again Paul!

"1) I can't begin to tell you how many props were tried (and ruined in the process) to determine the "best" prop for that airplane."

I remember many years ago looking at the back seat of Paul's car. It was completely covered with propellers. I couldn't imagine anybody who didn't get in a lot of midair collisions using so many props.

"It also flew in the wind well. The 1992 Nats on Friday was a good example, as well as the 1994 NATS finals (right Bob?)."

And the 2003 Nats.

I really appreciate all the work that went into this combination. I just copied the results and went flying. It works dandy.

Having seen Paul fly at more than one Nats
1 Lincoln Nebraska when it was windy enough to make your ears flap;
Paul flew his bad news and I couldn,t tell the wind was blowing , by
watching his plane ,with an st60 in a4 stroke mode.Paul said he didn,t care for the ST
At Vin cennes is was breezy, On Pauls last flight he pulled the plane
in a tight loop to cut the engine . coming out of the top of the loop, he he turned it into a sort of figure 9; the bottom of the
9 being the asphalt where he made a perfect touch down and roll out.
After that he smiled and looked around like take that guys.

So the only place I disagree with Paul is , on his self estimation as a flier;)

>
>>
>>Could you please elaborate on what he was doing to be
>>considered wrong, besides the small prop? More or less the
>>theory behind his setup.
>>
>>Thanks
>
>
>If you could fill me in on the "what's wrong", I could
>comment on that.

The crux of the "problem", as relayed to me in the mid-90's, was that that little gutless 40VF didn't seem to have the "grunt" you needed to swing a decent prop. Just think how well you would do if you could get some real meat up front, like a 14-6. Could have won by 100 points instead of just 50!

I think this was the same conversation when the problem with the "case seal on the 40VF kept blowing every 20 flights", a common problem as "everybody knew".

I said it didn't make any sense.

LAST EDITED ON Nov-19-03 AT 10:17 AM (CST)
 
I must agree with Bret that there really was not a problem with Paul's setup. From what I have seen of this combo it had more than adequate horsepower. I think Paul chose to setup his airplane to perform with smaller diameter props not that the motor was not capable of pulling larger diameters.

Smaller diameters, from my experience, produce less overall line tension but provide an easier turn. With the smaller diameter there is less gyro effect to overcome. What all this amounts to is what works for you. If you look at a hundred different airplanes there will be a hundred different ways to solve the same problem. Your combination works for you but may not be suitable for someone else for various reasons.

Hey Brett sort of like trying to explain thrust, drag, lift and weight.

LAST EDITED ON Nov-19-03 AT 12:10 PM (CST)
 
I never thought anything was wrong with his setup either. I just was wondering why people would think it wasnt correct when there is not just one "Correct" way. I didnt even know people did think that until that thread.

I tend to think that setting up a low response system works great. I mean isnt that what using a pipe is really all about anyway? And it works well with a smaller prop. There is less jump. The motor handles the load more easily in all attitudes. This equals less up and down response from the system.

What I see happening in my system is it does get a positive response from level flight to a maneuver. However when it gets into a maneuver it goes up a bit and just sits there steady as a rock. Then level flight and steps back down. It doesnt seem to move up and down as much as those who run larger props and lower compression setups DURING the maneuver.

If it starts cycling up and down during a maneuver more than I like I try to kill it off. I have found the more I can keep the motor really checked up and in a very "what is perceived to be" narrow range I can fly much more consistant patterns.

2-4 break on a pipe. Lots run it with great success but I still dont know if I get it. I ran it for a while and worked real good! Kept the plane very clean... But now I have seen the light and I think I understand what the original intent was...I think...

The 4s seems to be able to do this also. It has no choice in the matter.. Fuel draw is the main issue there. IMHO that is the number 1 issue with the 4s, "Fuel Draw"

I think most if not all competiton pilots have sorted out the combination that they prefer. Some choose two strokes with pipes and others choose two strokes with no pipe. There are still others who choose the four stroke route. Is one better than the other in terms of a distinct advantage? I think not. Success is based on how much you put into achieving it.

How many times have you thought that your setup is so much better than someone else? Most probalby many times. It's good to pass on the experience that one has garnered but to question others success is IMHO a mistake. There are a lot of things that Paul and others like him have made work very well. I have a gret deal of respect for that even though I would most likely not take their approach.

Paul and others are successful because of their dedication and willingness to try other methods. My hat is off to them all..

The top guys work hard to optimize whatever system they are using. I would guess that the difference among optimal systems is probably less than the difference between an optimized system and the same system with something out of whack, eg. a prop with half an inch too much pitch.

>>>with half an inch too much pitch<<<

Howard, be careful, it could be that last small difference, which can help you win!!!

I think the answer to the fuel draw problem is obvious. Pressure fuel feed. It's not an easy solution, nor one that would be easy to sort out, but it's obvious to me that if you want to run large venturis, then you pay the price and urge the fuel along. Either that, or you'll have to cut back on the venturi size.

Just Engines carries the Perry fuel pump.. maybe that'd be the best thing to use (unless crankcase pressure on a 4 stoke is possible, in which case you can use the other pump they sell, don't remember the name).

What a fantastic thread, this is a keeper. Thank you Paul for sharing your great wisdom with the rest of us.

Question for Paul or anyone that wants to jump in..

If a middle advanced flyer came up to you and said he was going to build an Impact, had both a VF-40 and Saito 56 which engine would you recommend he go with? Why?

Bob,

I think it hard to go completely wrong with either the 40VF or Saito 56 in an Impact. You'll get in more flying, sooner, with the puny little 40 'cos you're a guy who pays attention and the PW Combo is not only proven beyond doubt, it is also Plug-'n-Play. Even Rush had his running well in a very short period of time. (Read: Walker Influence.)

You would also enjoy a Saito-powered model, especially as you have some not insignificant experience with this type of motor.

Shorter answer: Don't ask us! This is such a close call only you can answer the question.

As to Paul's mention of a wide variety of fuels working well in the 40VF, I was recently witness to Mr. Chris Cox flying his 40VF-powered Saturn on YS 20/20 fuel. "Well, it works in Resinger's ST 60!" Yep. And never in my life have I seen a 40VF treated so poorly. Never have I seen small-bore two-stroke get that HOT! Less a few minutes time and a good propane torch, I didn't think you could fry one of these things to the point where 10 minutes later the venturi was still so hot neither Chris nor I could put our fingers on it to choke the engine.

Why were we trying to start it? The best way to get it cooled off was to run some methanol through the thing.

Next flight it was fine. Very, very tough motors.

Wow Dan, the first part of your post sounds an awful lot like a complement, better be careful or we will think your getting soft.

>What a fantastic thread, this is a keeper. Thank you Paul
>for sharing your great wisdom with the rest of us.
>
>Question for Paul or anyone that wants to jump in..
>
>If a middle advanced flyer came up to you and said he was
>going to build an Impact, had both a VF-40 and Saito 56
>which engine would you recommend he go with? Why?

40VF - turn-key operation and Nationals-winning performance.

>40VF - turn-key operation and Nationals-winning performance.
>
> Brett

Saito 56, 2002 Nationals winner (in addition).

>Question for Paul or anyone that wants to jump in..
>
>If a middle advanced flyer came up to you and said he was
>going to build an Impact, had both a VF-40 and Saito 56
>which engine would you recommend he go with? Why?

Wow...I hate to agree with Dan too often.....

It's too close to call. What ever suits your fancy. Ths 56 will give better line tension (probably due to the farther forward CG) and the 40 works quite well in still "thermally" air. Your choice!

"Shorter answer: Don't ask us! This is such a close call only you can answer the question."

Paul,

We rarely disagree. As above was my bottom-line suggestion to Bob Reeves, we are still on the same page.

HI Paul

good job at the TTs

I am curious what engine was in your plane when you won the Lubbock NATs and the U.S TTs that was after Lubbock?

And..Are you building a new P-51 for the worlds?

>HI Paul
>
>good job at the TTs

Thanks Randy!
>
>I am curious what engine was in your plane when you won
>the Lubbock NATs and the U.S TTs that was after Lubbock?

'94 was my first venture out with the PA 40. Used it in the TT's as well. Yup...One of those "puny" 40's I was talking about.
>
>And..Are you building a new P-51 for the worlds?

Yes...It's already out of the jig awaiting paint now. Currently, I am building new wing panels for the 2003 plane, since I broke one off, and broke the LG mounts in each (due to excessive weight savings). The repair of these added more weight than I thought, hence me nearly breaking the scales at the TT's this year! Should be back down to 62 oz on the 2003 version, and near 58 on the new one.
>
>Regards
>Randy

Yes...It's already out of the jig awaiting paint now. Currently, I am building new wing panels for the 2003 plane, since I broke one off, and broke the LG mounts in each (due to excessive weight savings). The repair of these added more weight than I thought, hence me nearly breaking the scales at the TT's this year! Should be back down to 62 oz on the 2003 version, and near 58 on the new one.
>

P Walker

You make me so mad sometimes. The 2003 porker is down to 62 ounces and the new model--one-piece, I assume--is predicted to be in the 58-ounce range?

As you're now painting the model, can I come by and have all the wood which was deemed just slightly too heavy? My most recent Impact indicates that either my gram scale is off or I don't even know what 5-pound wood is, much less actually own any wood in anything less than a 12-pound density.