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Old 07-23-2004 | 12:58 AM
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FlyerBry
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Default RE: lt-40 prop

sigrun, you have been so busy trying to launch a personal attack you have missed my point entirely. It is a simple fact that horsepower figures are a poor way to compare engines. To simply suggest that engine A is better than engine B because of a slightly higher HP figure is shortsighted at best.

The best way to compare engines is through torque figures and more specifically torque curves measured on a dynometer. Unfortunatly, this information isn't available to us. RPM figures are another attempt to make an "empiricial" comparison which in the end only tells us how fast an engine will turn a given prop on a test stand. No knowledge is gained in how well the engine will perform with that prop in the air. Of course if your goal is to fly your test stand then it could be quite helpful.

Another simple attempt to compare engines as well as props has been in the form of thrust measurments. This goes a step further than the RPM number from the test stand because it roughly tells us how much air is being moved by a given prop/engine combination. Again, this only indicates the peak output of that combination while telling us nothing about where in the RPM band usable power is being developed.

The fact is two stroke engines rarely operate at their peak RPM (where that HP measurment is taken) while pulling your airplane around the sky. If they did I would agree with your comparison of HP figures wholeheartedly. I've never seen anyone manage to take a plane up and keep it in a dive for the whole flight - it might be possible for half a flight that ends in a crash but then what fun would that be! [:@]

Now consider what I have just said and apply that to what we know about four-stroke engines. If you make a simple comparison of HP figures for a given displacement the two stroke would win every time! Granted, a larger displacement is required in a four-stroke to move the same plane as a two stroke but if you follow the general RC rule of using a higher displacement four-stroke engine and manage to match the HP output precisely (yes I realize that is impossible in all practicality) between the two stroke and four stroke then the four stroker would be the winner because of where in the power band the power is being made.

The TT .46 may share its roots in the OS .46 SF engine but that doesn't make it an SF. It is still a completely different engine. The same goes for the FX and AX. That is the comparison I was making earlier while talking about these two engines. If you simply look at the numbers they may as well be the same engine. Real-world experience has proven that not to be the case. That is why I stand behind my original post.

By the way, if you go back and reread my first response to your post it is quite obvious my point was that your experience (if any) with a TT .46 Pro is not up to the standard of this engine. I wasn't laying any blame on you as I did say maybe the engine was a lemon. Heck it could have been somebody else's engine which they tuned wrong. The first attack was made by you in your first response to my post. You accuse me of attacking the messenger when in fact it was you who did that very thing. You went on to say you are right because of "the undeniable empiricial evidence" and yet the only hard facts you have provided in all those words you typed are horsepower numbers that are only occasionally reached in real-world flight. I have just given you a full explanation as to why your theory falls short of reality. The simple fact is these engines are much closer in power than you are willing to admit. I say this based on my own personal experience and that of many others at local clubs and on these very forums. I have flown both these engines so I am speaking from first-hand experinece. Is one a little more powerful than the other? Undoubtedly yes. But they are much closer than you seem to want to admit. Why it is so hard for you to acknowledge that someone else may have had a slightly different experience than you is beyond me. I guess it is just easier to go on the attack and try to sound educated then have an intellectual discussion.

My pride has been quite happily intact all along, thank you. But thanks for asking.


ORIGINAL: sigrun

FlyerBry I don't know whether your launching upon such a pointlessly futile and 'crushingly' personal vendetta is down to your sense of injured pride due my rebuttal or simply an inability on your part to comprehend, be it due a lack of the the basic ability to deduce or reason called logic? But again you post only superfluous noise extraneous to either the subject or objective of the thread, the facts, or what was actually written by me. And your ad hominem slur that an ability to communicate either necessitates constant reference to the dictionary or is motivated by a desire to impress is most indicative of the weakness in your own 'argument', but perhaps more so of a pompous and insecure ego of your own?

Reading your post I am at odds to find what your argument actually is, as other than constantly and unnecessarily reaffirming and proving your personal owner pride in TT, (ie: unnecessary as it's accepted prima facie per se) you keep changing your point of debate.

Let's look at a few examples.

ORIGINAL: FlyerBry

is common knowledge that comparing engines strictly by the numbers doesn't tell the full story on how they perform in comparison to one another.
You might want to look up a dictionary yourself to understand what my previous referral to the frame of reference known as "the undeniable empiricial evidence" meant. However what is agreed as "common knowledge" is that the FX is inarguably more powerful than the Pro. I reiterate that apart from the empirical evidence supported by taching the engines, this is further publically acknowledged by TT. I suggest you take up your dissatisfaction and personal affront at the status quo with them, because at the present time, your obtuse argument is wasted in convincing anyone other than the unintentionlly irrational or yourself.

I invite you to do a search here on RCU and look at the posts for both engines. You will actually find more people who have had problems with the FX than the TT.
Assuming that this nonsense even contained an element of truth, what would it actually be indicative of?
A. The FX is more popular? = True. B. The FX sold in far larger numbers = true. C. The FX at one stage had a peeling liner problem = true. D. The FX is frequently recommended as a first engine to beginners who don't know how to tune? = true. E. All of the above?

I'll tell you what it's not indicative of. Power of the FX vs power of the Pro.

Is the TT a copy of the SF? Well I would say it is
If it's an acknowledged copy (thank you) of OS's FX predecessor, quite separate from the confirmation provided in TT's published power output statement and empirical testing, take an intelligent and informed guess what that reaffirms in relation to power output vs the FX?

So what's your beef? Are you hurt through somehow identifying with TT or feeling some sort of lesser being because of your predeliction for TT's 46Pro, which is acknowledged ispso facto by asssociation with the SF design a fine engine? That goes hand in hand with the an undenaible public domain acknowledgement of the power variance. I am almost as perplexed as I am bemused? How does attacking the messenger of that fact or either of OS's' contemporary engines help?

And you go on to say;

Either of these two engines will pull an LT-40 around quite nicely.
Well surprise,..surprise,..Gomer! When was it ever a point of contention, or indeed inquiry of this thread, that they wouldn't? Talk about grasping at proverbial floating straws as one stuggles to gain a place in the proverbial sinking lifeboat!

This past summer I helped a flying buddy of mine get his nephew set up flying on a used LT-40
The venerable anecdotal evidence. Hardly what one would denote a meaningful analysis conducted under anything faintly resembling controlled or objective conditions.

that came with a TT .40 Pro (not the .46) and he couldn't believe the power the engine had.
And now you start arguing from the position of a frame of reference related to a completely different engine!

maybe it is your misplaced pride that prompted you to jump on the TT.
Pardon my now raucous laughter. I've no owner pride misplaced or otherwise in either D. any of the above, or; E. all of the above. Perhaps best you analyse and address your own distorted reflection.

As it is I'm still unaware I had "jump(ed) on the TT". If you could kindly point out where I've done so other than in your own imagination? Quite to the contrary, my comments about both OS's SF and TT's Pro were complimentary. Predominently indicative of nothing other than an endorsement of their fine design accompanied by objective statement reference their relative power to one another and vs the FX/AX.

Your argument is an overgeneralization of the three OS engines you have mentioned.
You're grasping at that straw again. Contextually relevant generalisations, but you exaggerate to say overgeneralisation. Where relevant to the discussion I've presented quite specific supportive evidence, something you appear not to either appreciate, or understandably enough, can emulate in anything resembling a rationally justifiable defense of your own claim.

The general consensus at the club I fly at is the AX is a superior engine to the FX in terms of power.
Huh? Now who's exaggerating? Acknowledging the minor spec., and empirically observable increase, how is this truly relevant to the discussion at hand - let alone useful? Even OS only spec. 1.62ps claimed vs 1.63ps claimed? Wow! A whopping .01 of a ps gain! Talk about pissin' into the wind!

If you want to use illustration by example, the 50SX is a much more powerful engine, but the AX is essentially still very similar internally in terms internal design, torque, power & peak curves to the FX. Be it on paper or in action it offers nowhere near the characteristic peak output variance that existed and still exists between it or the FX and the SF, TT Pro, nor their sister and acknowledged powerhouse the 50SX.

In the final analysis two completely relevant facts remain.

The TT.46Pro is definitively less powerful than the O.S. Max .46FX. (proven)

The optimum most efficient prop for a TT .46Pro powered LT-40 combo in the training role flight envelope will prove to be either an 11x5 or 11.5x5. (supported by empirical trial and understood easily enough by anyone sufficiently erudite to understand applicable propellor theory, aerodynamics & interpret engine torque and power performance curves.

There it is. Should you wish to continue denying the former or accepting of the latter is by now fine by me. You can only lead a horse to water.