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Old Apr 05, 2012, 03:19 AM
Crashing into the sky!
jackosmeister's Avatar
Auckland NZ
Joined Aug 2007
7,179 Posts
There is no fear, there is only bungee. I dont have a problem with launching it?.. I once got an "experienced" launch man to do it, turns out he wasnt very experienced. Bungee only for me from now on.


Henke, if I remember right, your experience of an X is with less power, and it was nearly stacked into the dirt on the maiden launch too....
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Old Apr 05, 2012, 03:58 AM
"The Judge"
sebbe's Avatar
Sweden
Joined Feb 2006
5,762 Posts
It is easy to say: no problems in launching it, but once you felt the backside, it will haunt you.
The problem is mostly maidens, the plane can be wrong in something, an maybee you have to pay with a crasch.
when its all trimmed out, and you have launched a few times, then maybee you could say: its no problem.

I can agree one thing what henke said, start will smaller props, and get used to it, very good idea..

I have seen a few videos out there, where they go like 20-30% power, it goes away sooo nice, but as we know, this will kill the esc... so not the best idea if you have an ampdraw of 300% of the esc rating..
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Old Apr 05, 2012, 04:29 AM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
New Zealand, Tasman, Richmond
Joined Mar 2006
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I have no X, I wish I did! Maybe one day.... but hand launching a plane with a prop that is ~30% of the wingspan is always going to be massively torque dominated.
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Old Apr 05, 2012, 05:45 AM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Lšn, Ljungby
Joined Jan 2001
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Quote:
Originally Posted by jackosmeister View Post
Henke, if I remember right, your experience of an X is with less power, and it was nearly stacked into the dirt on the maiden launch too....
the angle of incidence or elevator trim can not be blamed on me...
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Last edited by henke; Apr 05, 2012 at 05:51 AM.
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Old Apr 05, 2012, 05:50 AM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Lšn, Ljungby
Joined Jan 2001
4,764 Posts
Quote:
Originally Posted by sebbe View Post
It is easy to say: no problems in launching it, but once you felt the backside, it will haunt you.
exactly, the focus must be on a straight launch, not on what can go wrong.

If you still try with large props and too much power for the ESC to handle a 2sec burst at 50% you are not up to it. Back of and take it in small steps.


Looking at the bungee video it looks bad too, why not give he plane a toss there too? just letting go is just stupid. Do it your self let it go at a slight upline (like I did) rather then a descent
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Old Apr 05, 2012, 06:31 AM
Registered User
United States, VA, Manassas
Joined Dec 2007
120 Posts
I don't have an X. "Yet?" It is on my list for consideration. Hand launches can be problematic if done by others. I have more anxiety about "experienced" helpers than the actual maiden. I recently maidened an Enigma and Sunracer. On the Enigma maiden, an "experienced" hand launcher volunteered. I told him to aim at a point about 30 to 40 degrees above the horizon. I take responsiblility for not being clear. I told him I would give a 3,2,1 count. On 1, I pulled the trigger. I see the plane leave his hand with him still in the wound up position. The plane rolled 45 degrees right, yawed a bit left, and pitched up. It was not a big or nasty event. He said he thought I was going to go on zero. Also scared the hell out of him. I handlaunch it and my Sunracer myself (including SR maiden) now. In the old days, we would hand launch our low wing Q500 racers inverted if the field was not mowed. We found that, pick a spot in the sky and throw at it as if to hit that spot, not like a baseball, but as a spear or dart. Aim lower if low powered, higher if plenty of power. Visualize (just like in baseball) hitting that spot. If you see in your mind a good launch, thats what you get. If you visualize a crash.....well. Again, maidens are the riskiest.

Brooks
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Old Apr 05, 2012, 06:36 AM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Lšn, Ljungby
Joined Jan 2001
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Quote:
Originally Posted by bpbrinson View Post
I don't have an X. "Yet?" It is on my list for consideration. Hand launches can be problematic if done by others. I have more anxiety about "experienced" helpers than the actual maiden. I recently maidened an Enigma and Sunracer. On the Enigma maiden, an "experienced" hand launcher volunteered. I told him to aim at a point about 30 to 40 degrees above the horizon. I take responsiblility for not being clear. I told him I would give a 3,2,1 count. On 1, I pulled the trigger. I see the plane leave his hand with him still in the wound up position. The plane rolled 45 degrees right, yawed a bit left, and pitched up. It was not a big or nasty event. He said he thought I was going to go on zero. Also scared the hell out of him. I handlaunch it and my Sunracer myself (including SR maiden) now. In the old days, we would hand launch our low wing Q500 racers inverted if the field was not mowed. We found that, pick a spot in the sky and throw at it as if to hit that spot, not like a baseball, but as a spear or dart. Aim lower if low powered, higher if plenty of power. Visualize (just like in baseball) hitting that spot. If you see in your mind a good launch, thats what you get. If you visualize a crash.....well. Again, maidens are the riskiest.

Brooks
+1 on that
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Old Apr 05, 2012, 07:05 AM
"The Judge"
sebbe's Avatar
Sweden
Joined Feb 2006
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What should the incidence on the X be ? or can I just thrust its good to go as i came ?
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Old Apr 05, 2012, 07:14 AM
Crashing into the sky!
jackosmeister's Avatar
Auckland NZ
Joined Aug 2007
7,179 Posts
Henke, since youve obviously not bungeed a plane before, there is over 10kgs of force on the thing, aint no throwing going to happen. The bungee can accelerate the model WAY faster and smoother, and more consistantly, than any arm on the planet.

I suggest you actually try take your own advice put 10kg on a bungee, and then try throw it. Please video it, as it would be highly amusing to watch


All this talk of the X being hard to launch is not correct by the way, as DUP says, anything with this much power, and a comparatively massive prop to wingspan has exactly the same amount of pucker factor. Take a look at the prop hanging viper as an example
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Old Apr 05, 2012, 07:15 AM
Crashing into the sky!
jackosmeister's Avatar
Auckland NZ
Joined Aug 2007
7,179 Posts
Quote:
Originally Posted by sebbe View Post
What should the incidence on the X be ? or can I just thrust its good to go as i came ?
0 all round works sweet.

I think Yuri's got himself a trick incidence meter now, but nothing to loose in double checking it.
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Old Apr 05, 2012, 09:25 AM
OTA
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Norway
Joined Aug 2008
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Quote:
Originally Posted by jackosmeister View Post
All this talk of the X being hard to launch is not correct by the way, as DUP says, anything with this much power, and a comparatively massive prop to wingspan has exactly the same amount of pucker factor. Take a look at the prop hanging viper as an example
It cant just be the prop size to wingspan to be blamed for the pucker factor. Also a lot of the setups on the X gives in excess of 80g/dm wingloading and that will also influence quite a bit. Many seems so focused on maximum power rather than good flying characteristics.
I dont have an X, but if I had, I would definitely have a launch mode with increased lift for the throw, and make sure to take off towards the wind (if any).

A lot of the crashes seems to be caused by silly throws though !?
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Old Apr 05, 2012, 11:23 AM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Lšn, Ljungby
Joined Jan 2001
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Quote:
Originally Posted by jackosmeister View Post
I suggest you actually try take your own advice put 10kg on a bungee, and then try throw it. Please video it, as it would be highly amusing to watch
We do all the time with gliders, don't see the problem. If you haven't already figured I try never to give advices that I don't use my self...

Henke = yellow dude

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Ejes SeaVixen extended version (10 min 0 sec)
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Old Apr 05, 2012, 01:03 PM
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drice's Avatar
United States, CA, San Diego
Joined Jul 2004
431 Posts
Afraid I have to agree with Henke.

Although the "simply release it" method is obviously working for you bungee-ers, there is a risk there that could bite you. Perhaps it never will, but the risk is there nonetheless.

When you simply release the X on the bungee, the plane is at 0 MPH air speed, and will continue to be below stall speed for some period, albeit a short period. The risk is that it could tip stall on the bungee and be pulled into the ground with great force by the bungee.

I have seen this happen...although the plane in question had more mass than the X so the acceleration on the bungee was not as strong.

I won't argue with the success that Jackosmeister is having, but I would argue that the safest method would be to pull against the bungee only as tight as you are still able to cock your arm backwards against the pull, so that you can provide the X with a throwing motion, so that the plane is above stall speed before it even leaves your hand.

Only in that way can you defend against the possibility of tip stall on launch.

On another note, that launch video of your friend "throwing" it was hilareous. I think the biggest issue with that launch is the fact that he didn't actually throw it so much as let it go. Since power appeared to have been applied while it was still in his hands, it looked like it was torqueing on him before he even let go of it, probably out of instantly needing to change his underwear.

I'm starting to believe that throwing it isn't going to be that big of an issue, provided it's straight and strong. I had my Enigma launched several times with no indication of any torque rolling whatsoever, and it was pulling more power than the X, and I've seen lots of F5B launches with absolutely no torque rolling at all, pulling 6KW.
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Old Apr 05, 2012, 01:19 PM
"The Judge"
sebbe's Avatar
Sweden
Joined Feb 2006
5,762 Posts
Quote:
Originally Posted by drice View Post

I'm starting to believe that throwing it isn't going to be that big of an issue, provided it's straight and strong. I had my Enigma launched several times with no indication of any torque rolling whatsoever, and it was pulling more power than the X, and I've seen lots of F5B launches with absolutely no torque rolling at all, pulling 6KW.
It must be a big differance between the Enigma and the X....

I have NO torque what so ever in any of my warbirds from 1 meter wingspan and above, even if they are overpowered, but the small warbirds twist pretty good on start. Power wise and prop size wise compared to size of the plane they have the same relationship..

I think there is something that is better against torqueroll when the size gets bigger..

16x17 prop on a 1.3 meter wingspan with that power could easy get you in trouble, even if you have the confidence..

I can not say anything about bungy start , as I know nothing about it.... I dont think I would ever try it, maybee because where I fly it would be problems just putting it up...
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Old Apr 05, 2012, 02:18 PM
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United States, CA, San Diego
Joined Jul 2004
431 Posts
Quote:
Originally Posted by sebbe View Post
I can not say anything about bungy start , as I know nothing about it.... I dont think I would ever try it, maybee because where I fly it would be problems just putting it up...
Hi Sebbe. Bungee launching is actually a really safe alternative, despite what I said above, and pretty easy to setup. My only warning about it is in regards to throwing the plane vs simply letting go of the plane.

All you need is a 4-5M section of 1-1.5cm diameter surgical tubing. You anchor one end in the ground with a tent spike. When you attach it to the plane, you only need to pull back about 5M to get enough distance for a safe launch. Maybe not even that far. So you don't need much space for the bungee, but you do need to put a spike in the ground temporarily.

I've never launched an X, but lots of other things. Hell, I've never even seen an X with my own eyes, even though I happen to own one. I hope to make its acquaintance in the near future.

Has anyone launched an X with a bungee just by putting the X on the ground and releasing it? I've done that before on hard ground. This would remove the risk of the tip stall issue. But it raises the issue of whether the X would get air under the wing for lift, as it might not be able to rotate for liftoff.
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