Author Topic: Whisper or Sunbird (Read 1956 times)

Thruxton · « **on:** February 24, 2015, 13:01:17 PM »

Anyone tell me how the Whisper glider (from South Coast Sailplanes) fly like.Need to step up from the foamies.Was considering a RCRCM Sunbird but put off by the fact it is a bit delicate and I have been told the fuse snaps in half at the slightest knock.I have been told the Whisper is a better buy

(I am talking about slope soaring these gliders)

Cactus · « **Reply #1 on:** February 24, 2015, 13:16:51 PM »

we have both down here.
both guys with the sunbirds are very happy with them ( one his first mouldie and not huge experiance ), and they've taken a few knocks, the fuz is much stronger than before.
another newbie to slope and mouldies has the whisper and is also very pleased with it.

i'd say the wisper is the slower and easier to fly, the sunbird is more agile and faster.

as a first mouldie i'd swing to the whisper.

GixerJas · « **Reply #2 on:** February 24, 2015, 13:57:14 PM »

As cactus mentions, I'm the person that bought a sunbird as my first moldie, so far I've not been gentle with it, it's proven to be quite tough (I've probably just jinxed myself) and its stood up well to some fairly harsh landings, even the uncontrolled ones. It's flown well across a wide range of wind speeds and its probably the only plane I fly every time I'm on the slopes.

Sent from my iPhone using Tapatalk

Butzi · « **Reply #3 on:** February 24, 2015, 14:51:39 PM »

I have a Sunbird too and I'm pretty sure there must be carbon reinforcement down the bottom of the fuselage as the tail boom feels extremely rigid and as yet I don't have any issues with stress cracks etc. I can only assume that the carbon lay ups seen at the front of the fuselage traverse the whole length of the structure. Superb sloper for the dosh and with crow braking can be landed on a sixpence.

Thruxton · « **Reply #4 on:** February 24, 2015, 15:19:22 PM »

Not sure what to go for now I really like the Sunbird and seen it fly at our local slope very impressed with the way it fly. So my heart is telling me to get the Sunbird and my brain is saying Whisper.Life is so difficult !!

Cactus · « **Reply #5 on:** February 24, 2015, 15:29:09 PM »

the whisper is bigger, and the fuz area for radio huge. it's much more of a crusier and momentum carrier.
the sunbird is more compact, a harder install, and a harder ( as apposed to soft not tricky ) sharper aircfraft to fly.

it's not as tricky as Luna or Typhoon

Geoff N · « **Reply #6 on:** February 24, 2015, 15:37:43 PM »

I had a Whisper from new my first moulded . Was not impressed. Wings did not fit correctly,had to file incidence holes to make every thing line up.
Comprehensive building manual was wrong reguarding flap horn placement. The build manual on southcoasts web site is newer but in Italian.
The trailing edge spars on mine were soft balsa and split along their length after a firm landing after carefully regluing now ok.
aluminum tubes that hold the vtail in place were soft and vtail quickly became sloppy and needed repeated glueing.
Wing tips quite weak
Flaps are top hinged so not a lot of flap movement.
Fuse quite strong no breaks yet.
Deffinitly a light wind /slow mouldie.
Never flown the sunbird

Cactus · « **Reply #7 on:** February 24, 2015, 15:53:40 PM »

is that the old or new one? sounds like my old whisper, but the new ones very different.

Geoff N · « **Reply #8 on:** February 24, 2015, 16:54:56 PM »

I got it about 2009

Cactus · « **Reply #9 on:** February 24, 2015, 21:06:42 PM »

old style then, totally different glider now

satinet · « **Reply #10 on:** February 24, 2015, 21:50:41 PM »

Sunbird has very thin wings so servo choice is tricky.

To my mind a faster more exciting slope model than the whisper though.

Alex xl, omega mini, typhoon or blade etc also worth a look.

The Aeromod prodij-hm flies great and is tough but quite expensive.

Your xmodels have the benefit of thicker wings and fuselages which are better for radio gear. Your typhoon etc limits b your servo choice but performance is good

GixerJas · « **Reply #11 on:** February 25, 2015, 09:20:01 AM »

I put 12mm servos in my Sunbird, it has raised servo covers so it wasn't a problem.

Thruxton · « **Reply #12 on:** February 25, 2015, 13:23:36 PM »

Well decision made I have ordered the Sunbird from "T9 hobbysport". Time will tell if it is the right decision or not

Butzi · « **Reply #13 on:** February 25, 2015, 15:02:37 PM »

Good choice! What colour though? And don't worry about the installation, there'll be plenty of advice (no doubt good & bad) waiting to come your way from the learned throng within this thread!

BTW, I have the 'Dennis the Menace' colours (red with black stripes), and it's very visible in most conditions.

Thruxton · « **Reply #14 on:** February 25, 2015, 16:30:08 PM »

I have ordered the red fuse with white and red wings. I have been told I will need to get some ballast for the Sunbird but I am not so sure it will need it I do not tend to fly in really windy conditions and I am still trying to work out how to fit the ballast tube also I am not sure what receiver battery to use in the Sunbird ,I was thinking of using a Eneloop AA 4.8 2000mph but I am not sure it will fit in the thin fuse?

Butzi · « **Reply #15 on:** February 25, 2015, 17:01:03 PM »

This is the battery pack I use: http://www.componentshop.co.uk/4-8v-2-3a-1600mah-flat-battery-pack.html
It fits very snuggly with plenty of power for a day's flying.

Butzi · « **Reply #16 on:** February 25, 2015, 17:09:28 PM »

Typical 2/3AA 1600mAh 4.8v install. The battery is held securely in place, but easily removed if required.

Cactus · « **Reply #17 on:** February 25, 2015, 18:02:43 PM »

don't worry about ballast, i fly my mini blade in 80 or so without most times.
it doesn't make you quicker, just punch through the turbulence better.
if thats not your bag you don't need it

satinet · « **Reply #18 on:** February 26, 2015, 09:24:16 AM »

Ballast does make a glider fly quicker

. The degree of how much faster is dependent on the weight, and it's true you need a lot of ballast to go a lot quicker. I nearly always fly with ballast as I fly a slope that has a lot more horizontal wind speed than vertical lift.

I would not build a sunbird without the ballast tube as it just limits the model for future use. IIRC on the sunbird the ballast tube is also quite handy to strengthen the fuselage.

Cactus · « **Reply #19 on:** February 26, 2015, 09:57:08 AM »

It makes you heavier, which for a given surface area means you should fall faster, ie fly faster.
But it also needs more lift to fly straight and level, which raises your AoA and induces drag.

Ballast if it's going to have the effect of making you faster would work on a vertical lift slope not horizontal where you can fight the lift trying to push you up easier.
10-12oz on a mini blade at staggy only seems to increase turbulence resistance and momentum. You gain very little speed and loose a lot of agility.
You also increase the risk of damage on landing.

Some swear by it, but for sport flying I think it's a bit Emperor's new clothes.

I'd agree with building the tube in, but i'd not make getting hold of the ballast my lifes ambition.

GixerJas · « **Reply #20 on:** February 26, 2015, 10:28:40 AM »

Last weekend two of us were flying our Sunbirds at Staggy in 30 to 35 mph, neither of us had ballast and didn't need it, but it's a relatively high lift coastal site without too much turbulence.

satinet · « **Reply #21 on:** February 26, 2015, 12:58:22 PM »

Quote from: Cactus on February 26, 2015, 09:57:08 AM

It makes you heavier, which for a given surface area means you should fall faster, ie fly faster.
But it also needs more lift to fly straight and level, which raises your AoA and induces drag.

Ballast if it's going to have the effect of making you faster would work on a vertical lift slope not horizontal where you can fight the lift trying to push you up easier.
10-12oz on a mini blade at staggy only seems to increase turbulence resistance and momentum. You gain very little speed and loose a lot of agility.
You also increase the risk of damage on landing.

Some swear by it, but for sport flying I think it's a bit Emperor's new clothes.

I'd agree with building the tube in, but i'd not make getting hold of the ballast my lifes ambition.

Adding weight means you fly down the same glide path, but quicker (i.e fly at best L/D at a higher speed). . It doesn't change your angle of attack. It does increase you minimum sink rate.

What makes me laugh about "no ballast" people is that if less weight equals better flying models, then why aren't you flying a super light model like DLG or f3j model all time. Answer, because more weight flies better. Well no, the right amount of weight flies better. ballast gives you choice to fly at different weights which suit different conditions or how you want the model to fly at a particular time.

Cactus · « **Reply #22 on:** February 26, 2015, 13:16:22 PM »

i flew my 6oz pitch bitch in 60 plus no issues at all.
nice and slippery.

i'm not sure in high winds you want to fly down the same glidepath.
the winds higher, it's coming up the slope faster, you want to fly a steeper path to have the same visual result to the ground.
in a purely flat field flight more weight will only cause a higher AoA to gain the required lift.
a lighter plane with the same thrust and drag will fly faster.

Slope is tricker, it's all about wing loading and drag, not just weight because the winds coming at you from a funny angle. you need a steep glidepath, but if you're slippery enough you can do this without resorting to lugging weight around.

i've yet to put weight in on an average day and find the glider sooooo much better to fly. it's just fatter.

swarrans · « **Reply #23 on:** February 26, 2015, 13:17:14 PM »

My view is that if you don't build with the option of being able to add ballast you will regret it. OK I don't have a Sunbird so can't comment directly on that, but my Luna and Skorpion are SOOO much more flexible having the option of adding weight for different conditions and they can also fly a LOT faster with more weight.

Simon

Cactus · « **Reply #24 on:** February 26, 2015, 13:30:37 PM »

as said, build it in, daft not to.
even on my Luna it's not that much fun to add it.
sure it gains speed quicker in the dive, and it holds that speed longer as it whistles past, and then climbs higher with it's momentum, but it's not actually quicker, just that speed for longer.

maybe thats what people mean by faster.

satinet · « **Reply #25 on:** February 26, 2015, 13:35:35 PM »

Quote from: Cactus on February 26, 2015, 13:16:22 PM

i flew my 6oz pitch bitch in 60 plus no issues at all.
nice and slippery.

i'm not sure in high winds you want to fly down the same glidepath.
the winds higher, it's coming up the slope faster, you want to fly a steeper path to have the same visual result to the ground.
in a purely flat field flight more weight will only cause a higher AoA to gain the required lift.
a lighter plane with the same thrust and drag will fly faster.

Slope is tricker, it's all about wing loading and drag, not just weight because the winds coming at you from a funny angle. you need a steep glidepath, but if you're slippery enough you can do this without resorting to lugging weight around.

i've yet to put weight in on an average day and find the glider sooooo much better to fly. it's just fatter.

I don't quite know how to process this post! Aside from bizarre stuff, yes you don't want too much weight on a flat field glider, which is why those models are light but have a ballast tube. It's also why, in say f3j, they compete with 3 models of different weights. The same physics apply (outside cornwall) in slope flying.

Cactus · « **Reply #26 on:** February 26, 2015, 13:43:50 PM »

competition is different, you're trying to eek out tiny differences.
for sport flying, i'd rather not.

what doesn't make sense? slopers fly into wind, if that winds coming up the slope you need to either be so heavy you sink faster through it, or aim down and fly through it with less drag.
what looks like a glider flying across the slope SaL is a glider flying at an AoA against the rising air, which means it's actually diving.

Butzi · « **Reply #27 on:** February 26, 2015, 14:03:49 PM »

Thruxton, here's a picture of the ballast tube in my SB. It's difficult to get a good picture, but I think you'll be able to see roughly where it goes.

satinet · « **Reply #28 on:** February 26, 2015, 14:27:20 PM »

If you fly with ballast it's more efficient than down trimming to fly through a body of air (i.e loose less height). That's self evident otherwise ballast would be completely pointless as you could just down trim to achieve the same thing (according to you more efficiently). The reality is that, at the same airspeed, you cover more ground with a heavy model than a down trimmed model.

If you prefer the way a model flies light that's fine. You want to trade off the benefits of heaviness for the benefits of lightness. That's the whole point - you get to choose.

Per my comment about it's more efficient on my slope to fly at a higher speed with ballast than it is to trim down. Flying downwards doesn't cover more ground, that's obvious - trying diving vertical and seeing how much ground you cover!

All that being said everything is within the context of the plane being flown as different aerofoils are designed to fly efficiently (low drag) at different Reynolds numbers. ballasting up a gentle lady isn't going to make it fly like a speed monster f3b plane. Equally models with a "fast" wing section obviously fly better when they are cracking on.

Anyway, ballast tube is the way to go and if gives you the scope for experimentation in the future.

Thruxton · « **Reply #29 on:** February 26, 2015, 17:00:55 PM »

Just looked at where you glue the aileron/flap horns on top of the wing under the bubble but is this going to be strong enough

?

Butzi · « **Reply #30 on:** February 26, 2015, 18:07:02 PM »

Here are a couple of pics that show how the horn goes in and how much of the rear spar that needs to be filed out to allow the pushrod and clevis through.

Butzi · « **Reply #31 on:** February 26, 2015, 18:11:37 PM »

The control horn should go through the balsa sub spar and as close to the trailing edge as possible, but careful not to break through the surface of the control surfaces. I used needle files to open up the required holes as I found it easier to control the amount of material removed. A Dremel type tool can be used, but you best have a keen eye and very steady hand!

Thruxton · « **Reply #32 on:** March 03, 2015, 10:18:17 AM »

Build almost complete .Now that old chestnut I was going to set the C of G at 65mm as per instructions but it seems everyone has there C of G a lot further back (70mm or more ) I am not to bother about it being aerobatic just want it to fly nice a stable .Should I stay at 65mm and work from there? ,

GixerJas · « **Reply #33 on:** March 03, 2015, 11:08:45 AM »

I followed Zim's guide in the Sunbird build thread. I started out with the CofG at 67 but I now fly without removable weights at a CofG of 80mm. For my taste it flies much better with the rearward setting.

Quote from: Zim on November 24, 2011, 12:58:52 PM

Settings for Yoyo:

RCRCM Sunbird Set-up Guide

CG at rear edge of joiner – approx 67mm from leading edge to start. Make the permanent weight to 80mm, with four removable weights giving you 67, 71, 75 and 78 as options. Many are now flying 78 and rear. Consider elevator throws may need dropping to 8mm each way when at the rearmost points above.

Aileron

(measured at tip)
Up 7mm
Down 5mm

Aileron (Camber) - see flap notes
Aileron (CROW) – up 5mm
Aileron (Snapflap mix) – see flap notes
Aileron (Reflex) – see flap notes

Flap

(measured at root)

Flap/ Aileron mix – up 8mm, down 7mm
Flap (Camber) – 3mm down worked out along the aileron
Flap (CROW) – 70 degrees
Flap (Snapflap mix) – 3mm up/down worked out along the aileron
Flap (Reflex) – up 1mm worked out along the aileron

Rudder

15mm left/ right at base

Elevator

(measured at trailing edge near root)
Up/ Down 10mm
CROW – down 7mm

NB Snapflap mix uses wing trailing edge moving DOWN with UP elevator and UP with DOWN elevator.

Thruxton · « **Reply #34 on:** March 19, 2015, 12:44:13 PM »

Did the maiden on the Sunbird today ,really pleased with the way it flew ,it did not need any trim changes flew great .With the crow brake deployed it lands a treat Glad I chose the Sunbird Looking forward to many more enjoyable flights with the Sunbird

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Author Topic: Whisper or Sunbird (Read 1956 times)