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Old Apr 27, 2012, 05:16 AM
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Jyvaskyla, Finland
Joined Aug 2003
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Originally Posted by DrFragnasty View Post
FYI
My Xplorer 3.5 full-carbon is flying at 2225g = 78.48oz
and it only loses out to bigger lighter gliders in zero-lift.

Verrrry interested in a 3.5ST & looking forward to any road tests and comparisons.

58oz = 1644g !
Everybody seems to repeat the experience that 3.5m does not quite match the glide of 3.8m version. This is not surprise, lift/drag ratio (and glide angle) is largely dependant on span and aspect ratio.

However min sink performance is less directly connected to plane size. Maybe the new really light 3.5 meter versions are the ultimate light air F3J ships.

Regarding the weight discussion,I just keep repeating my experience that 1800g something weights are really (too) light for 3.8m Xp1. Maybe the light weightis a benefit in totally dead air, but if there is any activity at all (wind or thermal/sink), weights up to 2.1kg seem to give very closely same sink performance with better glide angle (distance flight) and smoother handling (carries energy through the circle, less pilot workload).
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Old Apr 27, 2012, 06:06 AM
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Australia, QLD, Gold Coast
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Old Apr 27, 2012, 09:27 AM
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Quote:
Originally Posted by Tuomo View Post
Everybody seems to repeat the experience that 3.5m does not quite match the glide of 3.8m version. This is not surprise, lift/drag ratio (and glide angle) is largely dependant on span and aspect ratio.

However min sink performance is less directly connected to plane size. Maybe the new really light 3.5 meter versions are the ultimate light air F3J ships.

Regarding the weight discussion,I just keep repeating my experience that 1800g something weights are really (too) light for 3.8m Xp1. Maybe the light weightis a benefit in totally dead air, but if there is any activity at all (wind or thermal/sink), weights up to 2.1kg seem to give very closely same sink performance with better glide angle (distance flight) and smoother handling (carries energy through the circle, less pilot workload).
Thats interesting because in totally dead air I have typically found that the 4.0 even though its "heavier" (we are talking 4-5 oz only) will out float my 3.5's -

If I think the air is TOTALLY dead ill go for a full tow on the 4.0. Mine could be in the low 60's come SA -

You might be right Tuomo an 1800gr plane will likely lower the pilot load in the a thermal turn but at that point I have already unpuckered my rear and the extra load factor in this area has never really lost me a round. If you can get a well trimmed X into lift of any kind you are typically rewarded with allyour flight time.

Your position on ballasting in "active" air suggests active air + wind maybe?

Thinking J here Active air is where the real strategic opportunities come out...

In those conditions where the air is active and its obvious you are going to see lift in the round (somewhere and yes sink) then F3J strategy might dictate a short tow...ballasting is out for me in a short tow scenario. The lite mass "should" translate to a faster tow. This assumes I dont screw it up at the sticks which is more likely to derail any of our theoretical differences in performance variables

By the way Tuomo if you make it to SA introduce yoruself and ill buy you a round!
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Old Apr 27, 2012, 09:32 AM
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United States, CA, Mountain View
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Originally Posted by webbsolution View Post
Thats interesting because in totally dead air I have typically found that the 4.0 even though its "heavier" (we are talking 4-5 oz only) will out float my 3.5's -
That totally makes sense, since sink rate is directly linked to wing loading.
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Old Apr 27, 2012, 12:43 PM
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Jyvaskyla, Finland
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Originally Posted by Francesco View Post
That totally makes sense, since sink rate is directly linked to wing loading.
If launch time is limited, then smaller fast launching (and light) plane might have the edge. 4m Xplorer is really large in F3J standards.

Active air = we concentrate on flying thermals and avoiding sink, not on minimizing sink rate. I would say normal conditions. In those conditions it is practically the same how well performing plane you fly. Not much difference if it is 2002 Pike Superior or Prestige, everybody flies 9.50 something flights, unless big mistakes are made.

If there is a critical performance criteria for normal F3J conditions, it is the distance flight. I all big competitions (WC, EC, eurotour) we see surprising amount of landings outside the landing circle, even outside 75 meters... This happens sometimes also in very calm conditions. Risk taking is a part of F3J competition, but maybe pilots are sometimes over optimistic on how their very light planes glide?

No SA WC for me no Organizing national team was this time too difficult. Next WC should be much closer to me, I have heard Also Turkey EC 2013 is interesting. We would also like to see you webbsolution in Eurotour competitions.
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Old Apr 27, 2012, 01:29 PM
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Originally Posted by Tuomo View Post
If launch time is limited, then smaller fast launching (and light) plane might have the edge. 4m Xplorer is really large in F3J standards.

Active air = we concentrate on flying thermals and avoiding sink, not on minimizing sink rate. I would say normal conditions. In those conditions it is practically the same how well performing plane you fly. Not much difference if it is 2002 Pike Superior or Prestige, everybody flies 9.50 something flights, unless big mistakes are made.

If there is a critical performance criteria for normal F3J conditions, it is the distance flight. I all big competitions (WC, EC, eurotour) we see surprising amount of landings outside the landing circle, even outside 75 meters... This happens sometimes also in very calm conditions. Risk taking is a part of F3J competition, but maybe pilots are sometimes over optimistic on how their very light planes glide?

No SA WC for me no Organizing national team was this time too difficult. Next WC should be much closer to me, I have heard Also Turkey EC 2013 is interesting. We would also like to see you webbsolution in Eurotour competitions.
You have missed the context of explaining when I felt the 4.0 was better

"Thats interesting because in totally dead air I have typically found that the 4.0 even though its "heavier" (we are talking 4-5 oz only) will out float my 3.5's -"

In a dead air round ill not be doing a short tow. Ill take a full tow with the 4.0

- Active air rounds ill fly the 3.5 because it will be anticipated that I will find air and thus justify the short tow -agreed min sink is not an iossue when you are sure you are going to find rising air.

However the swich in context I agree its what happens at the sticks that makes the difference. I could screw up at the thumb level and somone with a 1990 model could beat me if they just flew better. No arguments there.

Now back to the X2 thread topic. I have just finished my build on my new new MK II - my previous estimation was without the stab (oops) so it looks like I am at 1682gr before CG - not sure how much ill need to add since I am using the 4 cell enloope I might already be nose heavy...however even if I I have ot add some weight ill not be adding 3/4 of an oz so ill still be just under 60 oz AUW -

This is a full strength plane - same layup I have been flying for a few years now so I have total confidence in its strength. If the wind is above 30 MPH on the ground I might have some trouble getting it fully ballasted without tungsten but thats an option that would allow 50% of the aircraft weight for ballast

If the goop on the pushrod housing dries quickly I might even get a maiden flight today!

eurotour...thats pretty dreamy stuff for a Canadian with two kids and an ex wife on the payrol. I was just telling LJ I was jealous of him getting to fly all over Eu and beyond. Maybe when I win the lottery or get stationed in Europe for work I would love to get my ass handed to me by you guys - its always the best motivator
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Old Apr 27, 2012, 02:04 PM
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United States, CA, Mountain View
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Quote:
Originally Posted by Tuomo View Post
If launch time is limited, then smaller fast launching (and light) plane might have the edge. 4m Xplorer is really large in F3J standards.

Active air = we concentrate on flying thermals and avoiding sink, not on minimizing sink rate. I would say normal conditions. In those conditions it is practically the same how well performing plane you fly. Not much difference if it is 2002 Pike Superior or Prestige, everybody flies 9.50 something flights, unless big mistakes are made.
Agreed, but you've probably missed webbsolution's point, he was talking about compared sink performance of two models, not about contest tactics.
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Old Apr 27, 2012, 03:27 PM
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AUW 1694 ! booya !

Model is in my shop charging - curing and waiting for a maiden- this will not happen today as I decided to add a little better JB weld application to the elevator ( along with also soldering) so that must cure overnight...
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Old Apr 28, 2012, 02:38 AM
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United States, CA, Torrance
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Somebody put some pics up already! Some of us don't care about all up weight or CG, we just want to see shiny paint.
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Old Apr 28, 2012, 08:17 AM
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+1 to that
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Old Apr 28, 2012, 10:33 PM
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Originally Posted by ak79 View Post
Somebody put some pics up already! Some of us don't care about all up weight or CG, we just want to see shiny paint.
OK stand by ill post some sexy pics -

I took my new X2 out for a stroll today at our tune up contest. The first few hand launches made it quite obvious that the planes lite weight make it incredible nimble. On the 4th hand launch whike setting the elevator trim I was close to thermalling out!

Next was the winch - at altitude the X2 is noticibly faster than the same span Xplorer of old. I had no issues covering ground. I actually played witht he elevator trim a bit because it seemed "too fast" but what I soon realized was that the plane was not locing any alt it was just moving fast so I left it alone.

Lift was indicated at every scenario and the wing has a very different feel for camber input. This is a vast improvement IMHO as it seems to allow me to try a lot of different camber input in a given patch of lift. The previous X would not respond well to added camber input likely because it already had a lot of molded camber to begin with... I have about 2.5 mm of camber setup on a slider and I can get it all into that wing and continue to push it hard. I did manage one stall. The recovery was just like the previousl X - instant and stable...

at 59 oz this A/C launches fast though we were only using braided line and TD winches it was apparent that if required a short fast tow might yield very good results.

My aircraft has a perfect fit in all areas and its a dream to put it together while the sun is just poking through the couds...I cant wait t get it out again for more test flights.

ill post some pics asap!
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Old Apr 28, 2012, 11:02 PM
Jody Miller
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Orlando, Fl
Joined Jun 2009
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Sounds like love at first flight...
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Old Apr 28, 2012, 11:03 PM
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So did you get the 3.8 or 3.5?
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Old Apr 28, 2012, 11:31 PM
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So did you get the 3.8 or 3.5?
That was a 3.5 Spread tow - I have a 3.8 ST SL and another 3.5 ST SL on the way though.

its a super sweet ride and I am positively sure that once you get your hands on it you will love it too!
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Old Apr 29, 2012, 12:49 AM
Fly R/C writer
Redlands, Ca
Joined Dec 2004
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First report on my 3.8 X-2. All up weight of airframe only, nothing inside....50.8 oz. This is a fully painted, ST with 2.4 friendly nose.

Mike
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