UK_Flyer

Just got this off the Jet forum and thought it was worthy of a post here :-

[link=http://forum.modelisme.com/t74787-premiere-mondial-o.html]http://forum.modelisme.com/t74787-premiere-mondial-o.html[/link]

Sprink

Would make throttle control interesting, not exactly immediate power up!

klhoard

My Feedback: (10)

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If you had a variable pitch prop and ran it at constant speed. . . . .
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Hmmmmmm, just as they spent all their play money on electrics. . .
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MHester

My Feedback: (1)

I think electrics just got dealt a serious blow at this year's Nats. I think a lot of people who were thinking they had no choice but to go electric have since reconsidered.

That being said I'll have a couple of electrics in my stable, but they will have company [8D]

-Mike

MHester

My Feedback: (1)

Oh and keep in mind I'm not talking about the very top pilots, I mean everyone else.....

-Mike

PeterP

Mike,

I would be interested in hearing your thoughts or anyone else's in the performance of electrics in the varied weather conditions you all experienced at the NATS.

I still believe the advantage of no smoke is electrics greatest advantage. I have been flying YS's for some time and the evidence the smoke leaves behind doesnt help the scores even though the judges should not be looking at it. I have said it many times before- judging is a very difficult task these days especially in F3A - many complex manouvers in a short space of time does lead to impression judging to some extent.

I havent actually judged a electric F3A model yet but I would be interested to hear from people who have and the effect it has had to their judging process.

Anthony-RCU

My Feedback: (2)

Excellent point on the lack of exhaust. It will give you away in many circumstances. Many pilots were struggling with the lower speed envelope of E Power. Mismatched radii and sinking rolls were the prime examples. When the wind picked up HUGE crab angles and power loss at the end of flights were also no help.
I am considering OS or Webra 1.60. The OS seems dead simple and cheap but heavy. The Webra with the TN carb and external pump sounds promising. On a students budget however I may just be using my RX's for another year.

MHester

My Feedback: (1)

I'm glad you said that, because that's pretty much exactly what I saw (and many others apparently).

I saw a lot of people having plenty of power with the OS 140, but they were all really fresh engines. All of the ones with some time on them seemed to be starving.

As for the electrics....well, I think they finally showed thier weakness. Or simply the fact that they have weaknesses. Some people had excellent electric set-ups, but a lot didn't and weren't prepared for the conditions. I don't think it's the "death knell" for electrics, but it certainly made a lot of people stop and reconsider whether or not it was a "must have". It is not, but you do need more power on tap.

What I saw was the slow speed and silly crab angles killing the pilots even with thier best flying. The power to penetrate that wind simply wasn't there. And some people pushed thier set ups to the point of failure.

I think the bottom line is what I have thought for a long time now, and Jason Shulman said it best....it's not without it's disadvantages, and you have to want to do it. That being said, the technology is growing by leaps and bounds all the time. We'll be "there" soon, it's just a question of when.

My solution will be a little different though. Why limit yourself to one or the other when you can have both? But I'm in no rush.

-Mike

klhoard

My Feedback: (10)

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Hybrid?
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ExFokkerFlyer

My Feedback: (4)

Wasn't this thread about a turbine powered pattern plane?[8D] Cool, but in my humble opinion, just from watching my jet buddies, a whole new nightmare... ECUs, fuel pumps, filters, ECU batteries... way too complicated and troublesome for practice day in and day out.

As far as the new electric debate... I wasn't at the Nats, but we've had a few contests out here in high winds... I never ran out of power, never damaged my motors, nor my batteries... never saw that happen, can't speak to that. But I think one thing that has to be said in this debate is that the "Electrical Revolution" is new... nobody really has all the answers yet. Two years ago the only set up to run was a geared motor with a huge prop... now we are seeing guys have really good success with much more simple and cheaper outrunners with smaller props. What's the answer? I don't know, but i'm pretty sure next year's trend will be different. It's an evolution, not a revolution. IMHO.

Also, just like the glow set ups, it takes time to get comfortable. You have to experiement with what prop is best in windy days, and on calm. What about really hot and humid days when the air density is lower? And most of all, don't take other people's word as gospel... try it yourself. What works on one plane may not work on another... same with different styles. An electric airplane is going to be slower than glow... but it doesn't have to crawl either...

Personally I think the wide body design in general is the bigger liability in the performance of electrics in wind. The main reason the wide body developed was to slow everything down... just using an electric motor with do that, and with people using ESC's with brakes, the wide-downline-slowing-fat fuselages aren't totally necessary... though the other big benefit is with the increased fuse volume the rolling manuvers are greatly improved. So I dunno...

Anyway, I hijacked this thread a little bit too I guess.... lol

Tom M.
"my hypocrisy knows no bounds"

UK_Flyer

ah who cares, if an interesting subject results and a discussion pursues then thats the point of the forum,

Turbine, personally scare me all a bit to much at the moment, besides standard pattern is expensive enough

Electrics, see above, just to expensive, 500 quid for some batteries come on lets get real

Crab angels . . . . . . who started talking about fish ?, that really is high jacking

blw

My Feedback: (3)

Don't have a turbine yet and I know that I will get one some day. Flew them in full scale so I understand a lot about the model engines. Spool up time is getting shorter and shorter with the new batch of turbines. I have to disagree with the reliability comment. A properly built system should be just as reliable as glow if quality components are used. Ok, there is wear on the engine but a pattern guy would have a backup anyway. I see it coming one day.

ExFokkerFlyer

My Feedback: (4)

I fly turbines for a living too... the design of a turbine is much more reliable than a recip, any which way you want to look at it... but on models... go to a jet show and see how many guys have ECU issues, filter issues... then see how many flights they actually fly in a week, month, or year compared to the average pattern competitor... it's much lower. I'm not saying that the planes are falling out of the air due to equipment failures, but on average I would bet that the technology is just not there for day in day out practice for pattern ships. Exhibition? Sure... love to see it, but it's just not ready for prime time yet... turbo prop wise especially...

Tom M.

rmh

wide bodies slow the planes down?
and the tooth fairy and the Easter Bunny exist

Derek.Koopowitz

Peter,

Having judged the F3A finals I can tell you that when the pilots flew in front of me... I wasn't thinking electric or glow. I was watching the plane. Besides, the wind and rain were making such a noise that I was unable to hear the plane anyway...

-Derek

f3a05

From flying them:
No difference downhill--main influences are: overall weight, tickover RPM, engine type, Prop diameter and blade area./blade number.
Much the same applies to deceleration in level flight.
Little difference in crosswinds---relative side area in front of,and behind, C.of G. much more influential

Flying advantages: Tall bodies are easier to see in side view,and the whole body "presents well" in this aspect(not just the fin and rudder.----But you have to trust the "Wings Level" part more.
All types of axial rolls are much easier----needing less rudder/elevator input, and with a bigger margin for error in how much to put in.

I don't really understand why, but the end bits of long co-ordinated manouevres such as complete rolling circles/loops-a good example is the 2-roll circle in F07--you definitely run out of rudder authority.

When I first saw the Oxalys, I thought that the Fin/rudder looked too short---perhaps that little T-wing was an attempted fix,
rather than a joke?

Angus Balfour

Strange. I've found the modern planes to have way more rudder authority verses the slightly older planes. Rudder authority on Synergy and Astral is phenomenal. Steve Burgess said the same with his Oxalys. Has the rudder rate turned right down it's that powerful. This was with no canaliser.

Only time I've hit full rudder in a rolling circle was down at Brandons practicing. Heavy X wind in meaning you really had to pull it in with rudder as you were coming back towards yourself. I actually broke the pin on one of the clevises doing this which was interesting.

A

ExFokkerFlyer

My Feedback: (4)

If you take a 2"x2" square flat plate and propell it into a fluid , in this case air, it's going to take a certain amount of force to keep it at a certain speed. If you want to change the constant you can say that for given amount of force, you'll get a specific speed through that fluid. If you increase the surface area of that plate, say to 5"x5", it's going to take more force to maintain the same speed, or you can also say that it's going to move slower through the fluid for a given power setting. It doesn't matter if we are talking about plates here or a rounded fuselage, we are still talking the same thing, frontal area.

With the wide bodied designs the drag has increased because the overal volume of the fuselages has increased, therefore increasing the wetted area. Drag is going to make something slower all other variables being constant. Doesn't mean you can't over power it... we do, we all do flying these designs. But the planes are more capable of a more constant speed... and that is the key word.

Also as to what or who holds the advantage glow or electric... aside from the smoke which I think is a hinderance, but not impossible to overcome. I think we could all agree it's the guy moving the sticks, still, and not what turns the prop. So far for me and the people I fly with electrics are more reliable... that makes me a better pilot because I can practice more. If you have an OS or YS dialed in and don't have any issues, and can practice to your heart's content... you are not at a disadvantage IMHO... CPLR won the worlds with a YS, we had several guys place high and or win their respective classes at the NATS with glow... Obviously not a disadvantage to them...

But that's also not to say that the electrics are at a definite disadvantage either. It's the person behind the sticks, not just at the contest but in the preparation leading up to it in terms of set up and practice.

But then what do I know... apparently I still believe in the Easter Bunny.

Tom M.

klhoard

My Feedback: (10)

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Hmmmmm, so what you're saying is that Andre Agassi could whup me handily with an $8.00 Wal-Mart tennis racket?
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Interesting. . . .
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blw

My Feedback: (3)

Coincidentally, I looked at the new copy of 3-D Flyer today and Q. Somenzine (sp?) was on the cover hovering a turboprop Yak. There was a Q&A section with him and he said that the plane weighed 12 lbs. Maintenance was a 25 hour bearing check, and a 100 hour overhaul. He said that it was reliable and that maintenance was not an issue. He said that spool up time (turbine lag) was around 1 to 1.5 seconds at 50% or more power settings. Not bad at all. The engine was a Wren and cost $5800. He is mostly waiting for variable pitch props for turbines. He was getting around 7 minutes a flight and 1 minute of smoke.

artistic-aero

The cover of Flyer looked a little photoshop'd to me... The 2 meter turbine is far from new, I remember seeing a Japanese (where else....) scratch built Pattern about 5 years ago. I'm presuming it never got past concept stage...

rmh

yes -- wetted area is up
and more wetted area = more parasitic drag

the "wide" part of the "wide " body is a style gimmick'
if one simply increases the vertical area of the fuselage-- the rolling maneuvers will smooth even more
the rather tall fuselage is not in vogue ----yet-- but having done fair bit of this , plus played with lots of foam aerobatic stuff - It sure looks like the tall , not as wide fuselage will eventually show up as a "new" approach

stek79

I agree with Tom.

So why do you say that a wider body doesn't increment drag?

From your reply it seems that you agree with us.

f3a05

Try flying an 11lb. widebody with a small prop, 2-stroke with a fast tickover, sharp trailing edges, on a straight downline that you haven't quite got the initial height that you wanted, and put a reversed 2-point roll in the middle of the downline, before pushing smoothly into an inverted 8-point roll(having of course taken great care to get the same radius on the top and bottom of the downline)

Then do the same thing with a 9.5 lb model with a narrower fus., a 4-stroke with a large diameter 4-blade prop on a really slow tickover, and thick trailing edges -and then decide which was easier..........

Exaggerating, of course, but factors other than the width of the body really do have a much greater significance on drag, in practice.

But that's just one opinion!

ExFokkerFlyer

My Feedback: (4)

f3a05,

the shape of the fuselage is just one variable of many... absolutely. How about an example though, where both planes have the same motor, same prop, same weight... same everything except that one is a 90's designed 'narrow' body, and the other is the latest trend 'wide' body. What would the result be then?

You can slow a narrow body down, and you can speed a wide body up... no question about that. But with everything else being equal or constant, the wide body is either going to fly slower, or require more power to fly the same speed. Drag is drag is drag.

Respectfully,

Tom M.