RE: Plastic Props
 

Well Gary, as was stated about 70 replies ago, the need for another lighter pitch cf prop would be to have a good prop that is able to run in the power band, around 22,900 to 23,800rpm... When I turned the 1:06 in Phoenix it was turning 23,700rpm, good for me...
then at the nats it was turning about 22,600rpm, not too good, this is where another choice in cf props would come in handy for new guys and guys that cannot make a competitive wood prop, FLorida, same way, so like I said west coast the current prop is fine and if I was only racing on the west coast, I would only need one prop, but Muncie, Florida and the entire se is too humid at hot for the current prop to work well....

RE: Plastic Props
 

Shaving the tips does work nicely.

RE: Plastic Props
 

Ed,
Dave has tested with trimming the tips, and said it works. I'm not advocating tip cutting, but I'd be much more in favor of it over an all new prop. If I can't turn the carbon prop high enough, I use wood. I haven't felt the need to have a higher turning carbon prop. There was a learning curve that I had to go through to make good wood props. Not all of them work, but I keep trying. Also, like I said before, I've made many props that will go fast under the right conditions, but can't even get out of their own way at other times.

John,
I understand the need for some people to have a prop that turns more RPM's. I've also given a way to get those RPM's without the need to come up with an all new prop. Again, Dave said trimming the tips works. I still haven't heard a reason why a lower pitch prop would be better to get more RPM's versus the current one with trimmed tips. In fact, what would happen if a new prop was approved that turned more RPM's, but turned out to be slower in airspeed? How would it benefit racing? More than likely, just trimming the tips of the current prop won't change speeds much at all, if at all.

GS

RE: Plastic Props
 

What ever happen to the original black prop 7.4x8 that work so well for most condition?
Why can we have that back as an alternative?

Fred was supposed to refresh the new mold with that same prop, but somehow it got changed. If I remember correctly, someone mentioned the new one has more pitch at the hub than the 7.4x8. The current 7.4x8.0 will not turn over 25,000 rpm on the ground on a good day while the previous one (7.4x8) did. The old black prop will benefit new comers and work on all condition if not most. Beside, no one will have to complain about too much load on their engine's.

Just my opinion.

RE: Plastic Props
 

Sam, The orginal mold was re-machined into the 7.4x8.0. Fred has said he doesn't know what's really different, as the program wasn't changed except for the addition of the ".0" to the designation. If something didn't change between the 8 and 8.0, I seriously doubt we'd be having this discussion. Also, if Fred doesn't know what's caused the differences, there's no way to replicate the 7.4x8.
GS

RE: Plastic Props
 

I kinda like Gary's idea of just giving a little lee-way in trimming up the tips. That way, you won't have to worry about new "super" props that smoke the wood. On some days, when the CF will only turn 22,300 it just doesn't go. It does not take much work to get that same prop up to 23,000+. I can't say that its a ton faster, but it is definately better.

Like I said earlier, I have a ton of slightly nicked CF props that if I could sand them a hair, at least I could reuse them.

Sounds like a good idea to me? I have no problem submitting this for a rule, but want to get all you "devils advocates" out of the way first :)

RE: Plastic Props
 

Dave,

I have no strong feelings on props one way or the other. Whatever is legal I will try. If there is going to be a rules change proposal and subsequently a rules change, please, please lets word it it in such a way that we do not spend the next two years arguing about the interpretation. There are enough of those as it is.

Ed S

RE: Plastic Props
 

I agree with what you are saying Ed. I will post my thoughts here and let the experts tear it apart. I would like to keep it simply written, and simply enforceable.

My basic thoughts are that the prop must remain a minimum of 7" in length and only the outer 1/4" of each tip may be worked.

RE: Plastic Props
 

I think that modifying props is a very bad idea.

The 7.4x8 was allowed because it was well tested. The 7.4x8.0 being allowed was a big issue not only because it was perceived as a "rule change", but because there were concerns about it not being well tested.

The APC site has two pages that should be reviewed:

1) [link=http://www.apcprop.com/Engineering/engineering_design.html]ENGINEERING DESIGN[/link]

2) [link=http://www.apcprop.com/Safety/safety_concerns.html]SAFETY CONCERNS[/link]

Here are some of the important snippets from those pages

If trimming of tips is allowed, the stronger engines that will turn unmodified props at acceptable rpms will also benefit from the lighter prop and will turn up even higher. I have yet to hear this in this discussion.

Additional new props can be approved under the current rule. Let APC properly research, analyze, and develop additional props if any change is needed.

If modifying of the CF prop is allowed, who is to say that the person doing the modifying has a clue about the ramifications of the modification? What if the tip modifications cause uneven stresses and result in thrown blades or exploding hubs due to harmonics.

RE: Plastic Props
 

As often as I've seen props with a tip chipped off from contact with the ground be used, and not fail, I highly doubt simply altering the tip will be an issue, however, I will agree it should be tested in some way. I seriously doubt it would be any more "unsafe" than some people's wood props. Remember, we are talking at the last bit of the tip being altered, not the whole blade.

I've said before that if more carbon props are allowed, and they ended up being faster, they could effectively eliminate wood props from being used. If that were the case, Q40 would only really be different than Q500 in the way they look. The cost difference between the two is really minimal, and that just depends on which airplanes you're comparing (for instance, Harold Sattler's Miss Candace is cheaper than a Vortex, and not much more than a Neme-Q+). One of the things I really enjoy about Q40 is the ability to rework wood props (and I doubt I'm alone, or everybody would already be flying only the carbon prop). I know that I for one, would seriously consider only flying just one of the classes (422 OR 428), and concentrate on it, rather than spend the money to have equipment for both events.

People have said reducing the pitch won't make the prop faster. I still haven't heard how they know that's the case? I "depitched" a wood prop in 1999 because it wasn't turning up enough, and was already down close to 7" in length. I used a heatgun to heat and twist the blade to a lower pitch, so the airfoil wasn't changed (yes, on a wood prop--a trick learned from Mike DelPonte several years ago). I then went and set the National record with it. Just because your first try at a prop doesn't work, don't give up on it and throw it out, keep working it. You never know when you'll stumble into something good. I think a lot of people will make a prop, have it go slow, and just throw it out. It's a lot faster to rework a slow prop than to start over with a new blank. I probably would be on the other side of this current issue if I gave up on trying to make good wood props.

Fred has said there weren't any changes to the program the recut the original Q40 prop mold (other than adding the ".0" to the pitch designation), but it caused a significant drop in RPM's. How do we know some "unknown" issue won't cause a new prop to be faster? Also, with all the FAI testing Fred's done the last year and a half, I'd be real surprised if he hasn't learned something that would make a new Q40 prop faster.

Something else to consider--What if Fred is able to come out with another prop, and it turns up enough, but turns out to be 2-3 seconds slower when it's hot and humid? (My former record prop is that way, it always turns up, but is a total dog when it's humid.) You'd have a choice in the current prop as it now, and is too heavy, or a new prop that is lighter but slow.....What would we do then?

I'm not saying I'm right on this issue, but I don't feel I'm any more wrong than anybody else that's made their opinions known. Out of everybody that's posted saying something needs to be done, Don's made the only arguement with a reason to have a lower pitched prop versus the current one cut down. I'd be interested in hearing other opinions as to why one method of obtaining the RPM's is better than the other.

Personally, I'm not convinced any changes should be made at all--I consider making wood props part of the learning curve of the event, just like learning to properly trim an airplane to fly a good course. I'm just trying to find the best way to go about making a change "IF" it turns out it's really "needed". I'm also curious why it's taken a year and a half with the "8.0" prop for this issue to come up if it is needed so badly. People in different climates have always had different issues in going fast, this prop is just one of those things.

GS

RE: Plastic Props
 

From Don,

Exactly, the playing field will be no more level than it was before, just faster for everybody.


From Dave,

See what I mean about wording. I can trim the prop to 7" then dress 1/4 of each tip. Correct?

I know, I know what you meant!

Ed S

RE: Plastic Props
 

Ed and Don,

Unlike in the past, when people were regularly running well over 24,000, and sometimes close to 25,000, most of the fast guys are setting their engines up to run in the 23,500-24,000 range. I know Mike DelPonte likes Gino's engines to trun right at 23,700 -23,800, and props accordingly. If somebody can turn the current carbon prop in that range, I'm not sure that trimming it to turn more RPM's will make it faster.

I'm not sure if Dave meant what he said or not. I personally wouldn't go for the 7" diameter and then an additional 1/4" to be worked to blend the tip (that's the way I read what he wrote), but I'm not going to right a proposal, so it doesn't matter, I'm basically just playing a devil's advocate on this whole issue.

GS

RE: Plastic Props
 

I think the rules should stay the way they are. From what I have seen, if you cannot get the APC to go fast then something else is wrong it’s not the prop.
If someone wants to trim a prop to turn more RPM figure out the wood and trim all you want, if you can’t trim wood what will make you think you can trim carbon

Lee

RE: Plastic Props
 

Gary, That is not a bad option, I am definetely not against tip cutting, that is what I do up here in Boulder to get them to go better when hot and humid... I have shown the apc cut down to be faster than my wood props on a ratio of 15-1.... So far the apc is the best prop I can run in most cituations, but I felt having another option when the apc is too much load would be nice, so that is why I was arguing for another option, it does not have to be another prop at all, maybe full on bore, do what you want to the apc prop, just as wood, then you would never have to worry about needing another prop... For now I would love to have the option of trimming my tips for proper rpm band...

RE: Plastic Props
 

If we're taking count of votes at this point, mark me down for not adding any new props but allowing the tips of the existing prop to be trimmed so that the minimum diameter of the prop would be 7 inches. That would be a .2 clip on each tip. No dressing or reworking of the tip should be allowed--if you're going to trim the prop, all you should be able to do is saw off the tips. Also, I think that if you clip the tips, the cut should be a straight line cut measured from the center of the hub and following the circumference of the circle; no raking or streamlining of the trimmed cut should be allowed.

My .02

Hey, another thought occurs... What happens when Fred wears out this mold and needs to re-machine it? We could be going through the 8 vs 8.0 silliness yet again.

We should never have allowed CF props in 422 in the first place.

RE: Plastic Props
 

Not exactly, if a motor is already turning 23,600 and you trim it down it will be in the 24,500 range, this guy is wasting energy....
a person that is 22,600 and trims tips and gets into the 23,500 range is going to go better than a person at 22,600, he may not go as good as a wood prop perfectly made for the conditions that is fully develeoped but turns 23,500...
In my opinion this would only level the field, remember there are guys that have the perfect size prop and it is fully developed and the tips are intact, this guy should be the fastest, cutting down a apc to get into the right rpm band will help, but not fully acheive the speeds of the perfectly designed prop for conditions.... He will do better, but not surpass the good wood prop...
From what I have seen, cutting a prop down to the right rpm helps, but does not by any means match a good fully developed wood prop that has the right diameter and pitch to turn the perfect rpm....
Just my opinion of course... JW.

RE: Plastic Props
 

I will have to disagree with you're last statement, apc props have only improved 422 racing in my opinion, some would not race at all, some of our local racers have stated so... People would not be as competitive, if they have not learned how to make a good prop or just by chance do not have the craftmanship skills to make a good prop, then they are at a disadvantage and would surely tire soon of being lapped and give up... I have seen my times come down by 5 seconds and would not have the fire or desire to continue if I did not have the oportunity to run the apc props, Shoot as I have stated before, even the pro's like the fact they do not have to carve the wood anymore and search the field for a good wood one that will cost you 25-50.00 smackers, just to be broken on the first bad landing.... So in my opinion the apc prop has helped qm much, much much more than it has hurt qm...
JW

RE: Plastic Props
 

I agree John. I also would not be flying Q40 if the APC was not allowed under the rules. Between Work, Family, and all the local races up here, just not enough time left in the week to test props. Especially when we can only fly 6 months out of the year.

RE: Plastic Props
 

Dave,

You took the words right out of my mouth!!!! Try to tell my wife and kids that I need to spend even more time in the shop prop-carving. If it weren't for the APC Q40 prop, I would never have attempted Q40. Pylon racing isn't my job - it's a hobby. If I were forced to spend more hours than I do now I would have to leave the hobby. I realize that I will never be a threat to those who spend hundreds of hours a week working on props and practicing - more power to them. I'll take all of the shutcuts I can find for now realizing that they still won't put me out in front. But at least they let me get in the game. When my kids leave the house for college in 10 years, maybe I'll make a few props. It was nice meeting you in Muncie.

Kurt Bozarth

RE: Plastic Props
 

Put me on the list of guys that would NOT be flying Q40 if we only had wood props. Fifteen years ago when we were still carving Q500 props it was a pain. I think we need one more APC Q40 prop size that will turn up in poor weather conditions.
Jerry-B

RE: Plastic Props
 

I do not have strong feelings about props. I will use whatever is legal. The whole "Tip rework" thing will cause endless arguments. What is wrong with having the same type of plastic prop rule as we have in 428 where the only limiting factor is a min. dia and no rework apart from balancing.?

In 428 the selection is large and I have not heard of any "Prop of the month" problem. Competitors select what suits them best. The selection being big enough to suit strong to tired engines in hot, humid, dry, cold, whatever conditions.

Ed S

RE: Plastic Props
 

Ed,

You hit that prop subject right on the head. I agree with you totally!

A toast of Rum just for you, Ed. :D

RE: Plastic Props
 

I will throw in some rum too, more props means more level field, which of course means more good racing, which means of course a pilots race or flying is the skill rewarded, not carving skills, I agree with Ed, make em more please...
John W.

RE: Plastic Props
 

Ok, I'll be the devil's advocate once more.

If the plastic props were to be completely opened up, wood props would be gone shortly thereafter. What realistically would then make Q40 different than Q500? Why have two classes that take the same skills and are realistically only 2 to maybe 3 seconds apart in time? At least now it takes practice at making props to get that extra little bit at some races (wood props are not superior at all races).

People have said they wouldn't be racing Q40 if it wasn't for the carbon prop, and some have said if more props aren't allowed some will quit. Who can say if all those that are currently running wood props won't quit if all they could run competitively was carbon?

How many people now can say they aren't competitive with the guys that go fast and win in Q40 simply because they are at a disadvantage with props?

I guess I still don't see a reason that I believe is worth the risk of increasing speeds and obsoleting a part of the event that people have put a lot of time and effort in to gain an edge. The way I look at it, they've earned any advantages through a ton of hard work and time. Is it really fair to them to take it away?

GS

RE: Plastic Props
 

Shouldn't Q40 differ from Q500 by more than just the way the planes look? By making several different carbon props in several different sizes, the craft of carving a good wood prop goes away. We already have two buy-n-fly events--424 and 428. Should not Q40 retain at least SOME of the craft/art of what makes them go fast?

Also, having several different CF props to choose from WILL make the planes faster. Making the planes faster makes them more dangerous and draws more attention to our activities from the AMA. Do this and you will shrink the existing pool of racers who have the ability to safely fly these planes. You will also make it harder for people to gain the skills needed to compete at the higher level.