Author Topic: "New" 25LA-s-RN (Read 13165 times)

Andrew Tinsley · « **Reply #50 on:** May 07, 2013, 10:28:34 AM »

Thanks for that Brett, I am not questioning your findings, in fact it is really good news, as I am finding FP20 to be getting a bit thin on the ground in the UK. I am still wondering why my LA25s are not in the same league as the ones you are using.
I will keep a weather eye open on Towers and maybe order one if there is a good deal. I am so intrigued as to the difference that I would buy one from Towers right now, except that I am about broke! The children are getting expensive and the old man is a sucker!

Regards,

Andrew.

Joseph Lijoi · « **Reply #51 on:** May 07, 2013, 10:39:52 AM »

Quote from: Andrew Tinsley on May 07, 2013, 03:46:57 AM

Thanks for that Brett. I still have one reservation. As far as I am able to determine, there isn't a new LA25. Everything I have been able to measure indicates the same timing etc for all the LA25s that I have been able to measure (new purchase this year, new purchases early last year and two very old LA25s). It just makes me wonder if it is simply a loosening of QC on OS's part giving good and not quite so good engines. The FP20s have been as like as peas in pods and I have a good number of them. The LA25s that I have flown (using the standard BBTU) have been equally consistent, but not quite as good a run as the FP20 and certainly no more powerful.
I have kept strictly to the BBTU specs for both engine types. I prefer the FP20 from my testing, but I have an uncomfortable feeling that we are not comparing like for like. Maybe there is a modified LA25 engine on sale and I just have old stock?

Thanks again for a most interesting set of results,

Andrew.

Please examine the LA"s that you speak of and tell me if there is a boost port directly across from the exhaust port. The "new" (not blue) LA that Brett cites does not. I doubt that this is a question of timing or fits. It is certainly cheaper to cut one less port. The experts can decide whether or not the blocked off port is helping things.

Brett Buck · « **Reply #52 on:** May 07, 2013, 05:58:28 PM »

Quote from: Joseph Lijoi on May 07, 2013, 10:39:52 AM

Please examine the LA"s that you speak of and tell me if there is a boost port directly across from the exhaust port.

As mentioned above, no, there is no boost port.

Quote from: Joseph Lijoi on May 07, 2013, 10:39:52 AM

The "new" (not blue) LA that Brett cites does not. I doubt that this is a question of timing or fits. It is certainly cheaper to cut one less port. The experts can decide whether or not the blocked off port is helping things.

Or, alternately, we can just see how it runs and decide based on that. Part of the philosophy of this experiment was to show that it is not necessary to either modify engines to get them to work, or to even know how they work, to get a functional system. It's interesting but it's idle interest. What I see far too much of, right now, is people trying to outthink the designers and shoot themselves in the foot with unnecessary/detrimental fiddling.

Two things are certain, objective truths - the current version runs much better in terms of run quality than the earlier types for maybe 5-6 years ago, and, it has MUCH more power.

Brett

Doug Moon · « **Reply #53 on:** May 08, 2013, 06:42:54 AM »

Brett,

Thanks for the info. I will be embarking down the smaller plane road here soon with the kiddos and this is nice to know. My last LA 25 from several years ago was pretty weak at best and not a manageable run.

Thanks

Andrew Tinsley · « **Reply #54 on:** May 08, 2013, 10:15:22 AM »

Hello Joseph,
As Brett says there is no boost port in any of the LA25 that I have. I don't ever think that there was, as my oldest LA25 must be amongst the first to be on sale in the UK.
The latest that I have was purchased this year. I have had all the P/L liners out and measured them up, even checked the timing too, in case the deck height was different. I have even checked head volumes. they are all within a spit of each other. The interesting thing is that they all run just about the same, competent runs about the same or a bit less than the FP20 with BBTU, but run quality is inferior to the FP20 with BBTU.
Brett knows what he is talking about when he says his LA25 are much more powerful than the old ones. Mine however are not so well endowed. There must be some differences but I suspect I don't have a new style LA25, so I am in limbo. If someone in the US finds a new and old style LA25, perhaps they could cast a micrometer over them!

Regards,

Andrew.

Joseph Lijoi · « **Reply #55 on:** May 08, 2013, 10:43:35 AM »

Quote from: Brett Buck on May 07, 2013, 05:58:28 PM

As mentioned above, no, there is no boost port.

Or, alternately, we can just see how it runs and decide based on that. Part of the philosophy of this experiment was to show that it is not necessary to either modify engines to get them to work, or to even know how they work, to get a functional system. It's interesting but it's idle interest. What I see far too much of, right now, is people trying to outthink the designers and shoot themselves in the foot with unnecessary/detrimental fiddling.

Two things are certain, objective truths - the current version runs much better in terms of run quality than the earlier types for maybe 5-6 years ago, and, it has MUCH more power.

Brett

I'm not the guy who suggests taking apart his Randy Smith motor. If it works it works. I am more than happy and grateful that your experiment continuesand includes something I can buy at the local hobby shop. That is an elegant solution. I am just curious what the difference is.

Brett Buck · « **Reply #56 on:** May 09, 2013, 09:39:13 AM »

Quote from: Doug Moon on May 08, 2013, 06:42:54 AM

Thanks for the info. I will be embarking down the smaller plane road here soon with the kiddos and this is nice to know. My last LA 25 from several years ago was pretty weak at best and not a manageable run.

I can pretty well guarantee the power. I got a bunch of reasonably predictable runs, and one perfect one, so it can do it. Whether it can do it with the same sort of repeatability as the 20FP remains to be seen.

After flying a bunch of square 8's, for a total cost of maybe $125, and a day and a half of work 20 years ago, I had to wonder how clever we have been putting Piped 61s in giant airplanes all these years.

Brett

Andrew Tinsley · « **Reply #57 on:** May 09, 2013, 11:01:53 AM »

Hello Brett,
I am very glad that it is you that asked the question "why have we been flying piped 61s on giant aeroplanes". I wouldn't have the nerve to ask that question here!
Importantly you make an extremely good point about what you need to be competitive at all but the highest levels. The simple FP20 with BBTU on a Flightstreak, is all you need to get a good way up the stunt ladder. I have a several F2b planes from piped VF40 to ST60 power. I can't fly them worth a fig, because I have a built in fear of destroying them. I fly the Flitestreaks a lot better because there isn' t the fear of losing it, a Flitestreak doesn't take long to knock out and I have a few FP20s stored away.
It is nice to experience what the big boys fly, but a Flitestreak and cheap power does it all for me.

Regards,

Andrew.

RandySmith · « **Reply #58 on:** May 09, 2013, 01:07:14 PM »

Quote from: Andrew Tinsley on May 09, 2013, 11:01:53 AM

Hello Brett,
I am very glad that it is you that asked the question "why have we been flying piped 61s on giant aeroplanes". I wouldn't have the nerve to ask that question here!
Importantly you make an extremely good point about what you need to be competitive at all but the highest levels. The simple FP20 with BBTU on a Flightstreak, is all you need to get a good way up the stunt ladder. I have a several F2b planes from piped VF40 to ST60 power. I can't fly them worth a fig, because I have a built in fear of destroying them. I fly the Flitestreaks a lot better because there isn' t the fear of losing it, a Flitestreak doesn't take long to knock out and I have a few FP20s stored away.
It is nice to experience what the big boys fly, but a Flitestreak and cheap power does it all for me.

Regards,

Andrew.

I vote for that too.... !! Brett please bring your FliteStreak and Bb FP 20 to fly at the NATs this year !

Randy

Brett Buck · « **Reply #59 on:** May 09, 2013, 02:09:16 PM »

Quote from: RandySmith on May 09, 2013, 01:07:14 PM

I vote for that too.... !! Brett please bring your FliteStreak and Bb FP 20 to fly at the NATs this year !

You laugh now...

In decent air it does the square maneuvers just about as well as most other airplanes and I can drill 5 feet like it was rolling on a pool table. It is less good at tracking in rounds and straight lines particularly in turbulence. That might be offset by the fact I could do 40 practice flights a day without getting tired. I literally fly the thing 3-4 times a year and after a few maneuvers I can do square 8s without really even thinking about it.

Brett

RandySmith · « **Reply #60 on:** May 09, 2013, 02:15:34 PM »

Quote from: Brett Buck on May 09, 2013, 02:09:16 PM

You laugh now...

In decent air it does the square maneuvers just about as well as most other airplanes and I can drill 5 feet like it was rolling on a pool table. It is less good at tracking in rounds and straight lines particularly in turbulence. That might be offset by the fact I could do 40 practice flights a day without getting tired. I literally fly the thing 3-4 times a year and after a few maneuvers I can do square 8s without really even thinking about it.

Brett

No I wasn't laughing, I wuz smiling, look above at my post this is a smile

, this is laughing

I wouldn't do that

But I agree with you so bring your FliteStreak and 20 FP to fly at the NATs, we can prove them ALL wrong !!

Randy

PS being serious, It is not a surprise to me at all that these fly well, I have been setting up OS FP and LA 20 25s for years, I have also flown, and seen many smaller full body and profile ships fly very very well with Enya 20 , 25, 30 engines, plus OS and others, and a very good fl;ying Nobler with an Enya 25SS, and there is no reason I see that a Nobler would not fly wonderfully well with an OS 25 LA.
Ask Bob Hunt how well the RD-1 and others flew with a Enya 25SS

Andrew Tinsley · « **Reply #61 on:** May 11, 2013, 04:48:17 AM »

Perhaps a smaller plane would handle the rough weather better than the large US stunters? Just a thought. Brings back memories of the fast diesel powered stunters that we used to use in the UK, before the US style machines took over.
Randy have you had a look at the latest LA25s? Even this years model (well purchased this year!) shows the usual LA25 performance, good but not as good as the BBTU FP20. Everything is the same on this model as the old ones, timing, port size, head volume and venturi diameter. It doesn't go as well as the ones Brett is using. I have the same set up that Brett uses (I think!). I don't like these little puzzles without an apparent explanation! I am loath to buy another LA25 as I am broke right now and I don't another of the old style La 25s, I have enough of those already!

Regards,

Andrew.

Dennis Moritz · « **Reply #62 on:** May 12, 2013, 07:29:50 AM »

Sport planes like the Skyray, 20-25 powered Streaks, Busters, Shoestrings, and the like, feel easy to fly. Why? Many reasons I guess. They're simple to tune and trim. No flaps, no complicated sophisticated big bucks engine, no $50 dollar pitch adjust prop, a weight box (sometimes), adjustable leadouts that usually work in the stock plan position and so on. Easy stuff. When built straight they zip along a bit fast (for a stunter), stay out on the lines, and (again, if straight) turn inside, outside, evenly. Confidence inspiring. I like doing the shapes with a jr. Streak powered by an FP15 needled to shreeking. A pocket rocket version of the full sized sports. A friend did a similar fun exercise with a jr. Magician powered by an equally abused LA15. Even these overpowered versions of the idea look like they're doing a decent corner, if you can do your part, fast. Wind. Weird wind changing direction. What wind. Among other things, I never saw one of these birds, full sized or shrunk, fast or moderately fast, hinge. I hate hinging. I never had (again, if built straight, controls free etc.) a difficult to diagnose and/or fix inside/outside turn rate differential. Flapped full bodied stunters that exhibit inside/outside turn rate issues mean... even when you've built in access to the elevator adjustment... this can be maddening to fix. Right. Engine and tank are out there in the breeze in a profile. Any problem, pop the rubber bands, undo the screws, or equivalent, replace or fix tank or engine. Obviously we've access to control horn ratios. I agree with Brett on this, our complicated stunt war wagons take a great deal more work, experience and expertise, to gain the potential edge. I have had more than a few of these birds be an enduring frustration. Never performing, even in contests, at a level equal to my best profile. Happened this past season. I wound up flying a modified Magician 35 as opposed to a Vector for points. The plane flew better and was way easier to tune and fly. My scores (modest as they are) were higher flying the Magish.

Brett Buck · « **Reply #63 on:** May 07, 2014, 02:09:36 PM »

Quote from: Andrew Tinsley on May 11, 2013, 04:48:17 AM

Perhaps a smaller plane would handle the rough weather better than the large US stunters? Just a thought. Brings back memories of the fast diesel powered stunters that we used to use in the UK, before the US style machines took over.
Randy have you had a look at the latest LA25s? Even this years model (well purchased this year!) shows the usual LA25 performance, good but not as good as the BBTU FP20. Everything is the same on this model as the old ones, timing, port size, head volume and venturi diameter. It doesn't go as well as the ones Brett is using. I have the same set up that Brett uses (I think!). I don't like these little puzzles without an apparent explanation! I am loath to buy another LA25 as I am broke right now and I don't another of the old style La 25s, I have enough of those already!

Some actual performance numbers for this engine. Powermaster RO-Jett 10% fuel, stock everything, stock APC 9-4 prop, density altitude -50 ft to 0 feet.

13100-13200 in a solid 4-stroke
13500 in a 50/50 2/4
14300 peaked out

For reference, a 20FP will do about 13500 peaked out on 15% fuel and it is in a 50/50 2/4 at around 12100 or so. This is stronger than the original 25LA.

LOTS more power.

Brett

FLOYD CARTER · « **Reply #64 on:** May 08, 2014, 09:52:27 AM »

It's amusing to think that the OS "factory-set" needle valve position would need no adjustment! I really doubt that OS actually RUNS their engines before shipping them out! No doubt they open the needle, like, 2 1/2 turns based on an average setting.

As far as the rear-mounted N.V.A. goes; if you are prone to crashing regularly, it might be a good idea to use a venturi-mounted N.V.A. I havent actually crashed in a long time, except when the engine dies overhead. In that case, a busted N.V. is the least important damage.

Floyd

Brett Buck · « **Reply #65 on:** May 08, 2014, 10:07:04 AM »

Quote from: FLOYD CARTER on May 08, 2014, 09:52:27 AM

It's amusing to think that the OS "factory-set" needle valve position would need no adjustment! I really doubt that OS actually RUNS their engines before shipping them out! No doubt they open the needle, like, 2 1/2 turns based on an average setting.

Hmm, I am glad you find that amusing, but I don't know why. The engine was certainly NOT run at the factory, based on how much it broke in on the first 20 runs.

However, if you control the tolerances well enough, there's no reason that you have to run each engine to determine the correct needle setting for break-in. Randy's engines are also like that, you preset the needle and it starts and runs correctly. The bigger variation is in the fuel used, but that doesn't vary enough - again, if you follow the directions - to make much difference in a break-in run.

Of course this is different from most of the history of modeling, but that's because most (not all, but most) engines made before about the last 25 or so year were so crude that it was anybody's guess what they did from copy to copy.

Brett

Andrew Tinsley · « **Reply #66 on:** May 12, 2014, 08:18:13 AM »

Hello Brett,
I finally bit the bullet and purchased a new LA 25 from Towers. This gives me a range of LA25 engines dating from some of the first to hit UK market to a brand new one. It makes a total of around 7 of varying ages. They all give similar performance to those you quote. So it seems that a "new" LA25 isn't a feasible conclusion for me. Like you, all I can quote are the test results.
Do you have any idea why our results differ so greatly? I am not doubting your figures for new and old LA25s. You got what you got and that is all there is to it! There seems to be a real difference between the early US imports and those into the UK. That is the only conclusion I can come to. Maybe the LA25s were current in the US before they came to the UK. So has anyone any idea when imports of the LA25 first occurred in the US and I will try to do the same for the UK. That could just be the explanation for the curious divergence of our results.

Regards,

Andrew.

Author Topic: "New" 25LA-s-RN (Read 13165 times)

Andrew Tinsley

Re: "New" 25LA-s-RN

Joseph Lijoi

Re: "New" 25LA-s-RN

Brett Buck

Re: "New" 25LA-s-RN

Doug Moon

Re: "New" 25LA-s-RN

Andrew Tinsley

Re: "New" 25LA-s-RN

Joseph Lijoi

Re: "New" 25LA-s-RN

Brett Buck

Re: "New" 25LA-s-RN

Andrew Tinsley

Re: "New" 25LA-s-RN

RandySmith

Re: "New" 25LA-s-RN

Brett Buck

Re: "New" 25LA-s-RN

RandySmith

Re: "New" 25LA-s-RN

Andrew Tinsley

Re: "New" 25LA-s-RN

Dennis Moritz

Re: "New" 25LA-s-RN

Brett Buck

Re: "New" 25LA-s-RN

FLOYD CARTER

Re: "New" 25LA-s-RN

Brett Buck

Re: "New" 25LA-s-RN

Andrew Tinsley

Re: "New" 25LA-s-RN