Wow sigrun, congrats! Finally a post that isn't so full of attempted insults that I can actually agree with some of your points. Of course not all - but we do all have our own opinions don't we.
First of all, may we agree to disagree. You have your opinion on how close these two engines are as do I. Just reading our posts will easily point out that they are like oil and water. If we went out and asked for a third opinion it may be very well different than that which we have already expressed through an overabundance of words.
Second, in your most recent response it appears that you are under the impression that my optimum prop suggestion in reply to the original post was an 11 x 7. Here is a quote from my original post.
"Back when I was still flying my LT-40 I tried an 11x7 APC and it pulled it without any problem. The sweet spot I'd say would be an 11x5 or 11x6".
If you were you under this false impression all along I can understand why you would be so definsive of the pulling power of the OS in relation to the TT. I never made any of my prior statements with this in mind so if you had I can see why you would believe some of my statement to be exaggerated. As it turns out our suggestions are roughly equivalent. You said you like the 11x5.5 and I said the 11x5 or 11x6.
I'll attempt to keep this as relevant as accurate reply allows. I would have preferred concise, but recognising what is achievable in dialogue with you won't attempt the impossible.
However first a humble request? If you must quote, could you do so with relevance? Top posting followed by quoting the preceding post entire is superfluous. The reader doesn't need the entire preceding post quoted when it can easily be otherwise referred to.
You got me laughing on this one...
You have yet to offer up a concise post. Why change your ways now.
As far as the quoting all I can offer is that I was short on time and wasn't able to give my response as much attention as I should have. The tools here on RCU make it all to easy to include the entire original post which was already too long. I was responding late at night while waiting up for my wife so I could take her to the hospital. We just had our third child yesterday.
First let's divorce the discussion of stupidly simplistic and inaccurate misinterpretive generalisations reinvented in each succeeding post by you such as "engine A is better than engine B". I never said nor claimed any such thing. You have yet again diverted the discussion into an irrelevant point of debate which was never a statement attributable to or claim made by me or in fact ever in contest. Just comprehend what was said, not what you prefer to imagine was claimed.
The generalizations started whey you listed three engines in relation to the TT Pro. You later went on to mention the OS .50 and yet jumped on my case when I mentioned the TT .40 Pro. With all due respect sigrun, you have quoted my posts then used them out of context just the same as you have accused me.
All that was ever originally said by me in response to your claims of the TT46Pro's power output vs that of OS' 46FX was that the claim = false (paraphrased). Nothing more was implied about engine superiority otherwise any more than I disparaged the SF or Pro other than pointing out their lower peak power outputs and design heredity both of which are supported by statements from their respective manufacturers as fact and omnipresence in the public domain as common knowledge
As for quote: "horsepower figures being a poor way to compare engines being a "simple fact", this equally is an utter nonsense, both contextually and technically.
Hmmm... You have just quoted my statement on comparing HP figures and called it utter nonsense. Then you go on to agree with the very point I was trying to make in the following statement.
Whilst acknowledging each manufacturer's quoted figures (usually DIN ps) figures are but one datum, uniformly exaggerated and previously mentioned specifically as such, in the absence of other independent and objective testing under controlled conditions they are the only quantitive datum to which most R/Cers have uniform access. That to exaggerate that the are the whole picture is yet another example of you reading things into what wasn't said in an apparent enthusiastically biased argument.
You so enthusiastically eluded to "the undeniable empiricial evidence" in your post and yet the only hard facts you offered were HP figures. You eluded to some statements made by TT but I have yet to see any evidence or even a description. sigrun, what evidence were you referring to, might I ask?
One never suggested that they shouldn't be interpreted contextually in conjunction with other objectively reliable data, which includes empirical testing by those with a clue. Sadly, this condition excludes the 'anecdotal evidence' of > 90% of the R/C community.
I agree. That is why we so often look to personal experience when trying to make comparisons between competing products - engines or otherwise. Considering the statement you just made about manufacturers numbers being exaggerated I can only assume you agree that sometimes personal experience is our best measure of one product against another. In this case our experiences are obviously different. Hence, our differing opinions.
All leading manufacturers who are intent upon competing for market share in the increasingly cut-throat US market for a slice of the R/C consumer pie exaggerate their figures. They do this to sell engines into that status conscious and competitive male dominated R/C market where a rampant consumerism indivisible from a material society consciousness abounds. Couple this with a 'culture' where "koOl faKtA rulz" and an abundant ignorance prevails of anything truly meaningful in quantitive or technical terms ensures only engine 'dick size' aka peak power claims count. The sales success of O.S' premium price'n pitched 50SX amply illustrate this phenomena. This is the paramount reason today that engine longevity doesn't mean ****, and invariably 95% of single cylinder R/C 2 aircraft stroke engine design today is Schnuerle ported, over-square and highly timed to produce an impressive quotable ps figure near or at the top of the sustainable, without premature demise or failure, rpm curve. Where that peak power is developed is only looked at let alone understood by a relative handful of R/Cers, and those of us who do understand don't fall into their target market of said easily duped rampant consumers.
I agree.
However the two important caveats are, (i) that the figures are quoted by manufacturers and subject to the public domain. They have much to lose in the being unable to substantiate them if challenged by a competitor, and; (ii) in the absence of other objective obtained quantitive results such as measurement by brake dynometer under controlled conditions by an independent credible source, they're far more reliable and accurate datum upon which to base comparitive power outputs than the aforesaid technically ignorant average R/Cers' anecdotal 'evidence'.
I agree with both point (i) and partially with point (ii). On point (ii), just as you stated earlier, these numbers are at times exaggerated. When and to what extent we never really know. Personally I put more weight in personal experience than numbers often provided by a marketing department. Especially when they don't appear to agree on some basic level. This, of course, is a matter of personal opinion. When it comes time to spend the money, it is up to the person holding the wallet who gets to decide which is more important.
As such the quoted figures are therefore of great assistance in this regard, and can generally be relied upon as a predictor of comparitive potential peak power output. That 'common sense' which is the domain of accumulated knowledge dictates that a technical understanding of how engine design influences power characteristics is necessary to be cogent of the contextual picture particularly regarding the usable power curve, and even this needs to be coupled with objective empirical testing to offer a truly accurate comparitive result.
The key term here being "potential." How often do we see someone posting on this site DON'T BUY XYZ ENGINE, ETC. after being disappointed in the performance, quality or any number of other "human" measurments that we base our satisfaction on. It is human nature (and just plain smart) to try and learn from others experience before spending hard-earned cash. Unfortunately, this is only accurate part of the time and isn't much better than trusting that the manufacturers have told us the truth.
Understanding this clearly implies that taching RPM figures under a uniform controlled condition using standard propellor/s (a measure of load and an ersatz brake dynometer in qualitative simple form), etc does offer meaningful data other than ammunition for a failed attempt at ridicule of the pragmatic methodology by you. The selection of an eventual optimum propellor suitable to engine curves considering the compromise of a particular model's flight envelope and intended role is a totally separate issue and quite complex discussion. Ideally this should of course be taken into account by all when purchasing an engine, but through human falliability is invariably ignored by the mainstream in their technical ignorance and that predictably prioritised quest of acquiring maximum 'dick size' status points required for peer approval powered by the ego's craving for recognition.
Your statement that tach results or manufacturer provided figures are meaningless in predicting usable power is fallacy.
Ok, now you are putting words into my mouth. The point I was making was that they don't provide a complete picture from which a fully informed decision can be made. To use the manufactures numbers alone is to put your trust in the word of the manufacturer - as you eluded to, it can be a hit or miss proposition. I never called tach results meaningless. They are, however, still only a piece of the overall, incomplete puzzle. Yes, alone, it is a good indicator of propeller performance when comparing one prop against another and a good way to find a starting point. This still must be followed up by real flight time to fine-tune the final prop selection. A stationary bench test is in no way able to account for all the variables associated with real flight. The least of which is the fact that the chosen propeller in flight is constantly in forward motion - a fact that is difficult at best to account for while testing propellars on the ground. I agree the topic requires a thread of its own to even begin to cover the subject properly. I also agree that many modelers would benefit from using a tach of their own and learning at least the basic knowledge needed to select a proper prop instead of always asking "which prop is best?"
Marrying prop with engine and airframe is an entirely separate and complex theoretical discourse, which I shalln't take further here than to comment thus. Whilst the 46's mentioned will happily throw an 11x7 at impressive RPM, that prop size is entirely unsuitable for the flight envelope of the combo about which the inquiry was made. That you recommend such a sizing and suggest not only that it pulls the combo otherwise implies to me that either you were have never flown an LT-40 with an 11x7, but more have but fail to perceive the inefficiency which by implication infers you have no true appreciation of the interactive dynamics involved. Once accelerated to cruise, an 11x7 will haul the LT airframe even though operating inefficiently well below the engine's torque and power curves, but by way of analogy it's like using 5th in a 1.8litre twin cam to drive a loaded MPV up - or down - a hill. The acceleration (and flight idle approach braking) on that pitch with that airframe is absolutely ****ful, no matter which of those .46s the preferred powerplant.
Which is precisely what my recommendation for an 11x5.5 was all about. I can't be bothered elaborating further upon this here. At this juncture either you understand or you don't.
I agree, see my earlier statement about my recommended prop size. I never said nor implied that an 11x7 is the ideal prop for this engine/airframe combination.
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.
They will
iff the engine is (i) propped appropriately, and; (ii) propellor is suited to the model design and its intended flight envelope. Problem is too so many R/Cers choose the proverbial shotgun to go long range varmint shooting or a .222 hornet to hunt elephant. That they don't is purely down to human error born of ignorance, a pertinent illustration of that specific point being equipping a .46 powered LT-40 with other than an 11x5 or 11.5x5. The fact that people ignorantly prop their engines outside their optimum torque and power curves or taking into account airframe drag and operating environment (role) has nothing to do with an engine's inherent ability to achieve them nor reflects accurately upon their achievable peak power output.
[/quote]
See my original post for my comment on running an 11x4.
You are clouding the issue with irrelevencies to the inital and only point of contention which from which you kick-off in constant digression fumbling in a presumed attempt to somehow make your claim = true or even somehow relevant. I reiterate that the OS FX is more powerful than the TT .46Pro. This is neither bad nor good, it is just a undeniable statement of fact admitted as such by the manufacturers repective claims of achievable peak power outputs. It therefore = true. There exists no further point from which you can logically argue which will to alter that quantitively conclusive evidence.
We know this to be true at 16,000 RPM if the numbers provided by the manufacturers are truly factual.
Your statement, however, true in one instance (at 16,000 RPM,) makes no mention of the rest of the RPM range where the engine spends the vast majority of its time in service. We can blindly assume that a given engine has a linear torque curve but this is rarely, if ever, the case. In fact, this very curve will very often have multiple "peaks" that are spread throughout the RPM range. This is especially true when considering two-stroke engines. For this reason the TT .46 may be making more power than the OS .46 at say 7,000 RPM while the OS may be making more power at 8,500. The key word here being "may" because we simply don't know.
Add personal experience to this and we are all open to our own interpretations which in this case has shown its own variations. I won't go so far as to say the TT is more powerful than the OS but my own experience hasn't proven that to be false either. What I have observed is these two engines are very close. Without a more elaborate comparison where an attempt is made to account for all the variables it is impossible to know for sure what these engines are doing outside of the 16,000 peak number we are given and can only assume to be factual in the case of both manufacturers. It is, after all, entirely possible that both manufacturers have exaggerated their numbers.
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.
Suggest you re-examine the internals of both examples to which you refer. Except for origin of manufacture or model nomeclature, they are so similar they are far from being "completely different engines" from an operational perspective which is clearly what was implied. Small mods to the piston skirt or other irrelevancies which affect only aesthetic appearance for the purpose of marketing NEW(ness) (assumed = better) or production cost ergonomics such as the substituion of 4 head screws instead of 6. In terms of stroke & bore, timing, practical operating rpm bands, torque and power curves, potential peak power et all, they are per previously quoted comparison respectively so similiar that the only false implication is afforded by (parahprasing you) "they are completely different engines". In fact, OS marketing exploits the AX's similiarity to and FX heritage cleverly pointing out the association as a positive. The quoted ps and operating rpm curves confirm it.
[/quote]
I have yet to see OS share the torque curves on either of these engines. Have you seen them published somewhere? I would be very interested in seeing their results.
... Achieving that optimum is up to the end user knowing how to prop the engine and model. Evidence abounds here of the ineptitude of people to achieve that. For someone who would favour or even suggest an 11x7 be used on an LT-40 powered by any of these engines speaks volumes of why you prefer the TT. I have no contest with your personal predeliction.
Again, I'm not sure where you were led astray in relation to my prop recommendation on this plane. I agree with your suggestion being right in the ballpark.
I'm curious about what you mentioned about the price difference between the TT and OS. Here in the states it is currently about $25.00 US and it was a little more when I purchased my first one. I did consider buying an FX when they were being phased out since the prices had come down with the new AX out. But I simply didn't need another .46 size engine at the time so I passed on the opportunity.
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 wish you were local so we could just do a show 'n tell type put up or shut up demo. Let me save you from the pitfall of further miscomprehension. As a little research will amply illustrate (& my personal experience supports) the consensus of empirical evidence is supportive of the respective engines specs., and as such is undeniable by any reasoning person.
[/quote]
You gave me reasons why you disagree with my claims - some had merit while others didn't. It only makes sense sense for me to ask you to back up yours.
I have just given you a full explanation as to why your theory falls short of reality.
Not at all. You've presented a load of irrelevant nonsense as to why you have come to the false conclusion that the Pro is the power equal of the FX based upon your experience by propping your Pro as inefficiently as others similarly operating FX's outside the optimum performance curves. This result of human ineptitude which has the potential to afflict an FX in terms of robbing it of potential power more so than the more conservtively timed and flexible Pro, you comfortingly label innaccurately as "real world performance". FWIW I live with aviation's real world realities everyday, waiting for the refueller, hoping bags held up by security won't miss me my slot and other considerations divorced from theoretical ideal. However once roling down the runway the theory and math stand up, compromised only by human ineptitude at manipulating the FMS, the forces of nature and the toll wear and tear extracts from engine & airframe performance.
[/quote]
Again, see my comment on the 11 x 7 above.
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
Me2. Nah..Nahh...
[/quote]
All those big words and you never came out and said what kind of personal experience you actually have with the TT. I was fishing when I asked that question. Thanks for taking a bite.
Is one a little more powerful than the other? Undoubtedly yes.
Finally.
[/quote]
But which one and at what RPM! As I said earlier I agree to disagree.
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.
Er..try to sound educated? Oh dear! If it wasn't your insecurity instead of mine, you'll have me quoting all those impressive credentials in a sig. An adequate command of language is not only necessary but enhances the ability to communicate & comprehend complex concepts which is a prerequisite of erudite exchange. Technical prowess assists greatly as well. In my own case, I have ample of these attributes. That you should imply otherwise reflects poorly upon you and your ability to present reasoned argument.
[/quote]
OK, since we are comparing credentials, I have degrees in both English and Journalism and I am an admitted techie since I currently work as a computer programmer which is where I have focused at the graduate level. I have to admit I find your use of the English language very intriguing. You definitely like using big words. In places it comes across as if you are simply trying to look authoritative because your grammar skills don't always seem to match. I don't mean that as a put-down, just an observation that came to mind while reading your posts. I didn't mention it, though, for a few reasons. First it is irrelivent to the topic. Second, I noticed you are from Australia. With all the dialects that exist around this planet of ours what I noticed as quirks in your language could be perfectly normal "down under" where you live. Third (I know, finally...) people typicall use language in forums that isn't up to their normal writing standards when on the Web.
Too bad we can't have some kind of "fly off" I'm sure it would be quite entertaining. A guy in my club is currently building a H9 Twist powered by a .46 FX which is the same plane I have my TT on. I am anxiously awaiting its arrival at the field so I can see a good one-on-one comparison.