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Friday, January 20, 2012

E-Flite Ascent BL 450 PNP - Fight Review

UPDATE:   After pretty light use, the E-Flite 370 in the Ascent failed without warning between two flights.  It landed fine, only to never run again.  Seems like a simple quality failure, attaching another motor to the plane works fine.  My Ascent only weighs 14 oz with a 7x3 folding prop drawing 8.5A flat out, well within the motor's limits.  E-Flite 370 moved to AVOID.

UPDATE:  Avoid the Ascent until you read:

UPDATE:  With little effort, I have been able to substantially improve the Ascent.  I substituted an E-Flite 370 motor and a lightweight 18A ESC (make sure any substitute ESC can brake (not break) the prop).  I removed the plastic casing of my Optima 6 and wrapped it for 6L like mass.  The Ascent's new base weight is 13.9 oz.  The new thrust-to-weight ratio with a 1000 mAh 3S and 10" Radian folding prop is a somewhat astonishing and improved 1.2 to 1.  

I crammed everything as far forward as possible to keep CG under control, and with a 1000 mAh 3S it looks pretty good at just behind the main wing spar, but hasn't been flight tested due to 20G40 mph winds!

Soaring weight and WCL is down 14% and T:W is up. I'm hoping for about double the flight time per mAh, due to the improved ratio of [power off:power on] and much improved performance of both.  

As they say in aviation, the rich get richer.  As it turns out I could have gone lighter still on the power system to get T:W under control, but might have had to slide the wing aft (easy adjustment - drill two new holes).  Using a 2S battery could be another easy adjustment.  

All that said, I think the 370 was a sensible choice if for no other reason than it is a simple drop-in replacement.  It takes about 5 mins to install, only because you have to tap-out the shaft and reverse it.


UPDATE:  Substituting a slightly modified 10" Radian folding prop gets the Amp draw down to 12.58 at full throttle, allowing a smaller battery and saving weight.  Since a 1300 mAh battery lasted 30-40 mins, I'm going to try an 800 mAh in the hopes of getting significantly longer flight times.  Going 2S saves another 5%.  Lightening the longer sail portion should be worth a lot more flight time than losing unused power on the margin.  

Battery options and weight, pending flight testing:   
Ascent oz
Batt oz
Soaring oz
Batt % Base
Turnigy 1300 mAh 3S
E-Flite 1250 mAh 3S
E-Flite 1000 mAh 3S
E-Flite 800 mAh 3S
E-Flite 800 mAh 2S

Also fixed: the 450 run very hot with the stock 11" prop.  I also added a slot for the front of the cannopy and velcro on the back, to eliminate the inconvenient and dangerous screws (mandates work inside a live prop arc).

Every once in a while I buy a plane on a whim, then wonder if I might regret it.  I was looking for something new, and cool and most likely aerobatic.  Maybe something with a gyro or two or three, or maybe a newer, bigger helicopter that technology and the economic depression magically made more affordable.  But all I found in two excellent hobby stores was the same old tired selection of RC models fashioned by Chinese slaves working endless 24 hour shifts in overcrowded factories, knee deep in filthy festering bacteria and squaller.  If only it was less expensive, I thought...

But then, stashed in a corner I found this handsome little Ascent, sans pricetag.  It wasn't the coolest gryro-driven mega-bat on the planet, but it had a certain uniqueness to it and it wasn't injection molded in a poison Chinese Styrofoam commune; so it might even fly decent.
After a brief myocardial infarction caused by a sticker shock induced arterial coronary embolism at the checkout counter, I took the bugger home.  I was mildly comforted the the included 450 motor, temporarily ignoring my stash of lighter, more powerful Super Tiger .10s motors.  At least it is all put together, I thought.  It is labeled "PNP" afterall...

Well, uhm, sort of.  The fuselage is PNP, but the wing and tail assembly are traditional ARF.  So we have a minor manufacturer integrity issue, but still, the kit isn't overly complex as far as ARFs go:
The fiberglass fuselage is sleek and gorgeous in gloss 
white.  I added an aluminum skid to the bottom (not shown).
The build took about an hour, maybe a little longer.  It's what all ARFs should be--almost ready.  The finished product looks sensational from the top, but is a bit too plain from the bottom--solid white trim, minus the wing tip art shown in the first photo.
The final product weighs 15.5 oz, with the only variable being your choice of receiver.  I was out of Hitec Optima 6 Lites, so I installed a straight Optima 6 for now.  That cost me 0.2 oz.  Still, the manual recommends an E-Flight 1250 mAh 3-cell, which weigh exactly 4.3 oz.  That makes the best case flying weight 19.6 oz.  The plane is advertised at 18-19 oz flying weight, which is only possible if you use a 1000 mAh battery or less.

The Ascent can maintain level flight with 15% throttle set.  As sold, max flight time is in the 30-40 minute range with mixed aerobatics and pure soaring.

With a Wing Cube Loading of 5.7, the Ascent is too heavy for a sailplane of it's size.  The problem is 100% due to E-Flite's botched choice of power system - a very disturbing, and very consistent trend - E-flite blew another one big time.  Let me be clear, E-Flite's choice of power systems are the absolute worst in the business - there is no more clueless company in popular RC design today. 

The Ascent has way too much power, and is way too heavy as a result.  With glide trim set, bringing in half throttle stands the motor-glider on its tail, 90 degrees nose-high.  Half the reason is massive motor overkill, the other half is a very heavy motor in the nose, demanding substantial up-elevator to establish best glide.  Uhg.

Build quality is very typical for Horizon ARFs: fair overall quality marred by an occasional potentially fatal lack of attention to detail.  On my second sortie's pre-flight control check, I noticed a near full deflection elevator that wasn't moving.  The thin ply control arm had worked it's way loose, or was possibly never glued in.  A drop of CA prevented certain catastrophic failure.

My wing-set was warped slightly out of the box.  It took a flight to notice, because the rudder came back trimmed well deflected.  I also noticed positive right roll in a dive, or low angles attack, which generally makes aileron more effective and rudder less effective.   Twisting the left wing under a heat gun relived some factory baked-in right aileron--all fixed.  Speaking of aileron, there are none, so check the wing incidence for true, or perhaps add aileron trim tabs.

This sailplane should really come with proper ailerons considering the nearly $200 price tag. An additional quality issue is one of my prop blades always hangs half open instead of folding back. 

The Ascent could be sooo much more if E-flight knew what they are doing, but it is still a ton of fun!  The heavy flying weight and silly power make the sailplane a good wind penetrater.   Soaring time is shortened by the fast glide speed, but the slippery fuse and wing look great slicing through the air at high speed in total silence.  The Ascent's high speed and lack of noise look a bit uncanny in the air.  Very cool.
First 10 minutes of a 30 minute maiden (HD camera limited).
Overall, I didn't expect to enjoy flying this sailplane plane half as much as I do.  Those who don't mind overpaying for a nice flying ARF will want to replace/halve the power system weight and battery size, though CG might be an issue.

Appearance: A+
Gorgeous top view; bland bottom view.  Sexy fiberglass  fuselage.

Airframe: A+
Sleek.  Occasional nasty stalls aggravated by heavy weight. 

Power System: D
Very heavy.  Very overpowered.  Rocket-like vertical hand launches.

Build Quality/Durability: F
Wrinkled, warped covering.  Elevator control horn loose.  Cheap prop.

Value:  D+
Pricey at $190.  No ailerons.  Heavy and small scale for the wingspan.

Overall Grade:  C- (stock), A (w/Z8RC fixes)
Unstoppable fun with mostly easy to fix quality gaffs.

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