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Old May 04, 2010, 07:40 AM
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Quote:
Originally Posted by Merlin45 View Post
.
.
The recommended Lipo (Avionics 450 30C) is 31g, according to the data I found.

What do you weigh yours at?

The 600 20C is 34.5g (inc wiring/connector). I donít have a 450 2S to weigh.
.
.
Cheers!
2S 600mah at 34.5g that was pretty light I guess I might have been overlooking something too I think Your 600mah 20C is OK if you get
the CG on the correct spot.

Weight of 450mah I believe was around 31g my 3S 350mah 37g.

I got the stock aiRium with Kyosho 2.4Ghz TX/RX. I've not checked
the RX weight but I assume ~10g

If I were You I would have seriously looked on the rudder and elevator
servo to move them forward somehow.

About the props: I indeed testet the 7x4SF and 8x4SF against 2S (roughly).
I believe the 7x4 would work with 2S but barely. With 3S I'm sure the
7x4 would work. I actually felt the pull and heard the RPM.

Note this is not GWS SF props who are only/mostly suitable for indoor.

But when I discovered that the Kyosho brushless had no problems with
the 8x4SF with 2S I will go for that. In my blog there is a Miles Magister
I've been using as a low winged trainer which is driven by a 8x4SF with
both 2S and 3S. With 3S I must use the throttle carefully because
the wings are ailerons are fluttering in dives.

The Miles was actually RAF's trainer for Spitfire and Hurricane pilots.
My version is not realy completely designed properly but ... it works.
I should have used 6mm Depron for wings (avoid fluttering e.g.).
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Old May 04, 2010, 12:15 PM
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I'm thinking the APC8x4E is a lot of prop for a 225gr plane. I use that prop on 3S for my Alfas which weighs in around 400gr and 33" wingspan or so.
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Old May 04, 2010, 04:11 PM
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OK, so weíre talking the same weights with Lipos then .

Quote:
Originally Posted by FLOEY View Post
I got the stock aiRium with Kyosho 2.4Ghz TX/RX. I've not checked
the RX weight but I assume ~10g.).
As far as CG goes, I would guess your 2.4GHz Rx is 5g heavier, which considering that itís mounted right next to the ESC, i.e. forwards, brings the CG achievable.
So how does your CG come in? 45mm exact? Upside down, slight nose tilt?
As you have the factory ďReady-Setď, that would be good to know.

Which is why I asked about weight of 2.4G Rx. Sure, you donít want to remove it unnecessarily, but if/when the opportunity arises . .
Even with my 9g 35MHz Rx right forward, correct CG is practically impossible. 47mm, yes, but 45mm? Hmmm.

Quote:
Originally Posted by FLOEY View Post
If I were You I would have seriously looked on the rudder and elevator
servo to move them forward somehow.
Moving the servos? Hmmmm, there are easier, and better, ways.

Quote:
Originally Posted by FLOEY View Post
With 3S I'm sure the 7x4 would work. I actually felt the pull and heard the RPM.
Did you ďWattsUpď with that prop? I think you will find that 7040x2B is too small, bearing in mind the stock size is 7060x3. You may frazzle your motor like that.

If you went to 2B, a good starting point for 2B would be 8050. Thatís why I first tested an 8060, and got the same power measurements. So IĎm pretty sure 7040 is too small.

Cheers.
btw: GWS-SF are floppy, but they are definitely good for more than just indoors. GWS Warbirds with 400-600grams use SF props quite successfully!
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Old May 04, 2010, 04:14 PM
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Quote:
Originally Posted by dude_109 View Post
I'm thinking the APC8x4E is a lot of prop for a 225gr plane. I use that prop on 3S for my Alfas which weighs in around 400gr and 33" wingspan or so.
The Airium IS 225g, . . but DRY!

Weíre talking 270g-AUW here, and if the stock is 7060x3, that should be pretty good for starters.
As mentioned above, 8050x2B would be approx. equivalent, AFAIK.

So what power are you reading with that prop on your Alfa, and with which motor?
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Old May 05, 2010, 12:37 AM
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Quote:
Originally Posted by Merlin45 View Post
.
.
So how does your CG come in? 45mm exact?
.
.
The CG was approx at the spot Yes. See sketch. CG was not an issue
when I crashed it was actually me who tried to keep the plane in the air
when I should have done a "controlled" emergency landing.

Total weight I should have checked that but since I go the stock
and recomended setup I expected it to be no issue.

Prop: I'm not too worried about the brushless motor, I fried my share
and I was not even close with the 8x4SF maybe with 3S it would get
hot. I will try the 7x4 if the 8x4 is no success but my experience
says the 8x4 will do. I'm not able to test now I'm at work far away from
home and my aiRium Spit.

If I get time fixing the motor mount and the weather conditions are
good I will do more test flights this weekend.


Prop: Update according to a Swede the aiRium Piper got a 245g thrust with 2S
(stock prop I assume) with 3S it is a blast 350g!!! So those who need more
power with stock prop 3S (my Hyperions 3S 350mah 26C is possible to squeeze
into the spit)
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Old May 05, 2010, 12:54 PM
flyit, crashit, fixit.
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Cg

We know that CG is not an exact science, but the method used to establish it and the point itself is pretty exact. Of course there is a tolerance range, and more rearwards will give more response (until itís too far back, in which case itís too late ).

As I said, with mine, 45mm is impossible as it is. Available CG range is, shall we say, between 49 and 47mm, but Iíd prefer to start with the rec CG, and work backwards form there.

Quote:
Originally Posted by FLOEY View Post
The CG was approx at the spot Yes. . .
I take it you mean 45mm behind the LE at root, yes?

So, at risk of repeating myself, are you checkinĎ it upside down, and is there slight tilt forwards at that point? (or level, or . . ?).
If not, then how are you doing it? (that's the context of EXACT I meant!)


Quote:
Originally Posted by FLOEY View Post
. . my Hyperions 3S 350mah 26C is possible to squeeze into the spit .
You said your 3S Lipo is about 37g; what dimensions please? Does it fit, or do you have to mod the fuse? 3S does sound like a good option.

Cheers.
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Old May 05, 2010, 04:06 PM
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Quote:
Originally Posted by Merlin45 View Post
The Airium IS 225g, . . but DRY!
What in the world did they do to beef up the weight compared to the P-40? Not a good sign. When I read 225gr on their specs, I was thinking the extra rudder servo and linkages to increase 25gr over the P-40... There was a guy who even striped down his P-40 to below 180gr flying weight.

Quote:
Originally Posted by Merlin45 View Post
So what power are you reading with that prop on your Alfa, and with which motor?
I'm using 1050kv range motors (Turnigy2209 and KDA20-28M) that are rated for 15amps. I haven't tested WOT as I don't normally fly in that range. At 50% throttle, I'm usually pulling 2.5A or so on 3S lipo.
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Old May 06, 2010, 12:38 AM
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Quote:
Originally Posted by Merlin45 View Post
I take it you mean 45mm behind the LE at root, yes?
My CG was approx at 45mm, I will post a photo later marked it on the wing.
I did not check upside down I just did a rough check with my fingers.

If You are unsure about the CG please follow this procedure:
1. Optional to avoid damage: Remove prop and spinner
add piece of foam as replacement to protect plane.

2. With all control surfaces neutral. Hand launch plane as a glider
preferably down hill onto soft high grass or something that
minimize damage at impact.

Watch the plane: If it stalls it's tail heavy. If it dives forward it's
too nose heavy and so on.

Quote:
Originally Posted by Merlin45 View Post
You said your 3S Lipo is about 37g; what dimensions please? Does it fit, or do you have to mod the fuse? 3S does sound like a good option.
Cheers.
My Hyperion Litestorm CL 3S 350mah 26C is
according to sales info
Weight: 36.9gr
Size: 34 x 60 x 10.3 mm

But I'm a bit unsure about the thickness ... got to measure that.
I had to squeeze it in so some sanding may be preferable.

Just ordered 3 from the local supplier they were on sale
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Old May 06, 2010, 03:26 AM
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Hey Dude!

Quote:
Originally Posted by dude_109 View Post
I'm using 1050kv range motors (Turnigy2209 and KDA20-28M) that are rated for 15amps. I haven't tested WOT as I don't normally fly in that range. At 50% throttle, I'm usually pulling 2.5A or so on 3S lipo.
Thanks for that!
Cheers.
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Old May 06, 2010, 03:27 AM
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Lump in the battery compartment!?!

Quote:
Originally Posted by FLOEY View Post
My CG was approx at 45mm, I will post a photo later marked it on the wing.
I did not check upside down I just did a rough check with my fingers.
Floey, my CG is also approx 45mm . . . when I do a rough check .
You will get a much more accurate idea if itís upside down: balances better. When it tilts ever-so-slightly forwards, thatís the CG youíve got.

The ďapprox 45mmď, that Kyosho advise, could be 44 or 46mm, as I understand it, but 2mm will make a lot of difference on this size plane, so ďapproxď is a bit of a joke.

BUT, I would assume from Kyoshoís advice, that the 45mm CG is possible: but perhaps only with the 2.4GHz factory version.
(Thatís why Iím so curious what the 2.4G Rx weighs, because with a 35MHz (9g) Rx it is not possible).
IĎm sure that mine would fly as it is, but I want to use the 45mm as a starting point.
As mounting the 35MHz Rx right next to the ESC could give problems, Iím looking for a solution which enables putting the RX further away, but still getting CG right. If 48mm was ok, that will make life a lot easier . .


Quote:
Originally Posted by FLOEY View Post
If You are unsure about the CG please follow this procedure:
Thanks, but I am .

With the glide-test; yeah, sure, but Iíd leave the prop & spinner on (I'm too lazy). In long dense grass (or corn) luck would have to have run right out for any damage to occur.
Iíd have it powered up in any case, ready to hit the skies if it went OK.

Quote:
Originally Posted by FLOEY View Post
My Hyperion Litestorm CL 3S 350mah 26C is
according to sales info
Weight: 36.9gr
Size: 34 x 60 x 10.3 mm
. . But I'm a bit unsure about the thickness ...
The 10.3mm thickness would fit easily, and 60mm long is no problem, but the 34mm width is too wide to fit into the battery slot ENTRANCE.
You would have to remove the edge lip at front sides of cockpit to get that Lipo in. The battery hole itself is big enough once you get past the lip at the entrance. And where does the wiring exit?

GET THIS. . .
Have you tried looking, from the rear, down into the battery compartment? Try it!
Thereís a block of (what looks like) wood(?), which acts as a stop for the Lipo, on the LHSide only. If this got removed, the Lipo would move forward 15mm. CG problem solved .

Cheers!
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Old May 06, 2010, 06:48 AM
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Quote:
Originally Posted by Merlin45 View Post
.
.
The 10.3mm thickness would fit easily, and 60mm long is no problem, but the 34mm width is too wide to fit into the battery slot ENTRANCE.
You would have to remove the edge lip at front sides of cockpit to get that Lipo in. The battery hole itself is big enough once you get past the lip at the entrance. And where does the wiring exit?

GET THIS. . .
Have you tried looking, from the rear, down into the battery compartment? Try it!
There’s a block of (what looks like) wood(?), which acts as a stop for the Lipo, on the LHSide only. If this got removed, the Lipo would move forward 15mm. CG problem solved .

Cheers!
You must have a different plane (I've not measured the Hyperion) but
I squeezed it in and out. There is no woden block inside see attached
exploded view. As far as I remember it was the thickness that I noticed
was tight. I will travel home for the weekend, I will definitely look into this.
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Old May 06, 2010, 09:20 AM
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Quote:
Originally Posted by FLOEY View Post
You must have a different plane ..
As far as I remember it was the thickness that I noticed was tight.
Could be. Both mine are the same though, and the Lipo hole is for sure 30mm wide, and at least 11mm high.

I've already checked out that Kyosho exploded diagram: thereĎs no wooden/something block shown on it.

Bet when you look at the plane youíll see it though!
Anyone else wanna play? . . Guys??

Iím trying to find out from Kyosho what it is, but MFRs donít like people hacking around with their products, so not optimistic about a sensible answer. I can only think itís there to stop the Lipo moving too far forward . . .(or itís a footrest for the pilot )

Btw, having trawled for the n-th time through this thread, noticed that apok (also with the 2.4GHz) canít get the 45mm CG either, and he tried with a 600mAh, as I have.
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Old May 06, 2010, 09:14 PM
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Quote:
Originally Posted by Merlin45 View Post
Btw, having trawled for the n-th time through this thread, noticed that apok (also with the 2.4GHz) canít get the 45mm CG either, and he tried with a 600mAh, as I have.
I've done two test flights with 8x4 prop. With 3S 350mah it was ok but
not convincing. With 2S it definitely lacked power.

So I ripped out the guts of Spit to do bench testing.

Here is some initial weights:
Brushless motor 30g
ESC 18g
RX (2,4Ghz) 10g ok

Motor+ESC = 48g that is on a such tiny bird way too much.
I'm used to 20g + 10g =30g

With my motor and ESC I'm able to shave of 20g !!!

Total weight of my plane 8x4 prop 255g (30g LiPo)
then 20g is a lot!

Merlin Your CG issue: If the plane glides properly forget the
45mm it's real physics that count for flight performance.
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Old May 07, 2010, 04:31 AM
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Did bench test the original Kyosho brushless against a
http://www.hobbycity.com/hobbyking/s..._19g_Outrunner

Can't say which one is better at efficency/thrust but the Turnigy
weight is about 20g against Kyosho 30g, Turnigy got the prop saver
that fits my favorite prop 8x4SF. The Kyosho 10A ESC weights 18g
my old thrusted Himodel ESC's at 10-12A weight about 10-12g.

I will replace the Kyosho stuff with my Turnigy 2204 and Himodel ESC
in my Spit and use a 3S 450mah 25C LiPo instead. Then I wll get
a thrust/weight ratio of almost 1:1.

Conclusion(my view)
Kyosho the aiRium series needs a update. Less weight more power
= much more fun to fly. Those who want to fly "scale" better buy
bigger planes.

I will wait buying the Me109 until this happen or I get it dead cheap.

Anyway I love this scale! I think Kyosho's initial idea is/was good but
it can be done better!
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Old May 07, 2010, 09:41 AM
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Quote:
Originally Posted by FLOEY View Post
RX (2,4Ghz) 10g ok
Thanks for the Rx weight! That helps.

Quote:
Originally Posted by FLOEY View Post
Total weight of my plane 8x4 prop 255g (30g LiPo)
then 20g is a lot!

Motor+ESC = 48g that is on a such tiny bird way too much.
I'm used to 20g + 10g =30g
Floey, thatís all well and good, and I totally agree that the ESC & Motor are too heavy.
I measured the motor at 31g & ESC at 19g, on my 50mg digital balance, and my AUW is 270 with a 34,5g 600 Lipo, stock prop. Why the 20g difference I wonder?

How do you intend to retain the CG, once you have saved 10g on the ESC, and another 10g with motor?
You will be having SERIOUS CG problems. (You know that the Spitfire is reknowned for CG difficulties, I guess?
The Me109 less so, but both of these models have the same power system I assume).

Even with the (heavy) stock items, I canít get the CG right.

Using a heavier Lipo would be sensible of course, but at the end of the day, youíll be back to the ~270g AUW, though with much more efficiency of course.


SO . . . . HAVE YOU FOUND THAT WOODEN BLOCK YET????

If you could get it out, you can get the Lipo 15mm further forward, moving the CG forwards as much as possible. That might just counteract the weight saved with Motor/ESC. Then the AUW may be down by about 20g.

Or do you have another plan to retain the CG without, adding ballast??

Cheers.
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