HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Aug 21, 2011, 06:03 PM
Earthbound Skyhound
StarHopper44's Avatar
United States, NC, Richlands
Joined Jun 2011
5,046 Posts
Quote:
Originally Posted by theothercliff View Post
Whether he asked or not, he and other beginners that don't already know it could benefit from knowing that they should not just soar (slope or thermal) for an hour past LVC cutoff even though it may be safe for the airplane. Even if the plane is OK, the battery won't be.



Although the actual cutoff voltage (point of zero output voltage) of many BEC's may be as low as 2 volts, useful output as far as RC is concerned generally becomes reduced at 7 volts for a 5V regulator, and for 5V linear BEC circuits at least follows at about 2 volts below the input voltage when the input is below 7V. If you have 6 volts left on your ruined battery for your input, you probably have no more than 4 volts coming out of your linear BEC. If the 3 cell LiPo battery only has 6V on it, then you are not going to get much current out and will be lucky to be able to move your servos at all without causing at least a receiver or servo failure to perform.

Do you guys that know differently really want to make statements that can cause a beginner to make an incorrect assumption and loose an airplane?

Cliff
Lots of good, and interesting commentary in all that, gents. I think Cliffy came closest to the driving concern - that a too low battery even with sufficient voltage, very likely won't have the neccessary amperage becuz of electro-loss.
Good point too that losing a battery's better'n losing a plane.
Thank you all!
StarHopper44 is offline Find More Posts by StarHopper44
RCG Plus Member
Reply With Quote
Sign up now
to remove ads between posts
Old Aug 21, 2011, 06:24 PM
You can't take the sky from me
scott page's Avatar
United States, MI, Hell
Joined May 2009
6,318 Posts
Quote:
Originally Posted by Reegor View Post
I saw this at the local field this morning. It puts the motor out in the airstream - looks like a very good idea to me. But I haven't built mine yet - any comments before I go this direction?

Unfortunately I didn't get the name of the designer, but it wasn't me.
Well if that's not a heat sink on that inrunner I'll be dipped and fried.
scott page is offline Find More Posts by scott page
RCG Plus Member
Old Aug 21, 2011, 06:27 PM
Earthbound Skyhound
StarHopper44's Avatar
United States, NC, Richlands
Joined Jun 2011
5,046 Posts
I've thought about getting a Tx LiPo pack, if for nothing else, it's rechargability -- but the couple times I've explored the offerings, I can't get a fix on exactly what I'd need. The 8x AA's laid side-x-side in series provide 12VDC of course, but packs I've seen under 'Tx' are only 11.1, so....??? I just crammed in some hi-quality AA's. (Energizer Industrials, #LR06DP4 Alkalines - the one hospitals use, if anyone's interested)

My Tx's battery compartment measures (with a hair on the conservative side) 115 x 45 x 13mm; the last two dimensions equating a AA's height & span. Can (& will, please) someone recommend a specific LiPo pack that'll fit that size compartment? And how do you hook it up? I could figure something out, but rather than cuttin' wires & soldering in a plug there might be a more convenient way that I don't know about - like some kind've adapter? Anyway, would appreciate some advice there. I'd like to retain ability to use AA's for a backup system if that's feasible.

Que?
StarHopper44 is offline Find More Posts by StarHopper44
RCG Plus Member
Reply With Quote
Old Aug 21, 2011, 06:31 PM
Earthbound Skyhound
StarHopper44's Avatar
United States, NC, Richlands
Joined Jun 2011
5,046 Posts
Quote:
Originally Posted by scott page View Post
Well if that's not a heat sink on that inrunner I'll be dipped and fried.
(Clearly defining the owner as some kinda freak of nature!!!)

JUST KIDDING!!!!!!!!!!!!!!!!!!!!!!!!!!!111one
(With my luck, he'll be a member here!)
StarHopper44 is offline Find More Posts by StarHopper44
RCG Plus Member
Reply With Quote
Old Aug 21, 2011, 06:35 PM
Why so serious?
2500GENE's Avatar
United States, FL, Cape Coral
Joined Dec 2007
5,972 Posts
Quote:
Originally Posted by theothercliff View Post
Whether he asked or not, he and other beginners that don't already know it could benefit from knowing that they should not just soar (slope or thermal) for an hour past LVC cutoff even though it may be safe for the airplane. Even if the plane is OK, the battery won't be.



Do you guys that know differently really want to make statements that can cause a beginner to make an incorrect assumption and loose an airplane?

Cliff
Of course not and I don't think I did. I was responding to your statement. Flying past the LVC warning is never a good idea and the fact we're even discussing it is ridiculous.
2500GENE is offline Find More Posts by 2500GENE
Reply With Quote
Old Aug 21, 2011, 06:38 PM
Gravity impaired
jrjr's Avatar
United States, NY, Wolcott
Joined Nov 2004
1,516 Posts
Quote:
Originally Posted by StarHopper44 View Post
I've thought about getting a Tx LiPo pack, if for nothing else, it's rechargability -- but the couple times I've explored the offerings, I can't get a fix on exactly what I'd need. The 8x AA's laid side-x-side in series provide 12VDC of course, but packs I've seen under 'Tx' are only 11.1, so....??? I just crammed in some hi-quality AA's. (Energizer Industrials, #LR06DP4 Alkalines - the one hospitals use, if anyone's interested)

My Tx's battery compartment measures (with a hair on the conservative side) 115 x 45 x 13mm; the last two dimensions equating a AA's height & span. Can (& will, please) someone recommend a specific LiPo pack that'll fit that size compartment? And how do you hook it up? I could figure something out, but rather than cuttin' wires & soldering in a plug there might be a more convenient way that I don't know about - like some kind've adapter? Anyway, would appreciate some advice there. I'd like to retain ability to use AA's for a backup system if that's feasible.

Que?
The energizers you refer to are 1.5v each. NIMH cells are 1.2v each. I take it that you mean you want to get a TX pack (transmitter) so you can recharge it. If you currently have 8 cells that equals 9.6 volts. 11.1v lipo may be pushing it voltage wise. Some people use them in place of 8 cell packs but Spektrum for one will not honor the warranty if they know about it. It works in some cases, some it doesn't. In my DX7 I made up a 2500mah NIMH pack and can run it for a looooong time between charges. Newer units may come with a lipo already. I don't know what your stock radio has as far as cell count or plug configuration so more info is needed.... and someone with the same radio may have a better perspective.
jrjr is offline Find More Posts by jrjr
Reply With Quote
Old Aug 21, 2011, 06:41 PM
Gravity impaired
jrjr's Avatar
United States, NY, Wolcott
Joined Nov 2004
1,516 Posts
Quote:
Originally Posted by 2500gene View Post
of course not and i don't think i did.
+1
...
jrjr is offline Find More Posts by jrjr
Reply With Quote
Old Aug 21, 2011, 06:42 PM
Why so serious?
2500GENE's Avatar
United States, FL, Cape Coral
Joined Dec 2007
5,972 Posts
Quote:
Originally Posted by StarHopper44 View Post
I've thought about getting a Tx LiPo pack, if for nothing else, it's rechargability -- but the couple times I've explored the offerings, I can't get a fix on exactly what I'd need. The 8x AA's laid side-x-side in series provide 12VDC of course, but packs I've seen under 'Tx' are only 11.1, so....??? I just crammed in some hi-quality AA's. (Energizer Industrials, #LR06DP4 Alkalines - the one hospitals use, if anyone's interested)

My Tx's battery compartment measures (with a hair on the conservative side) 115 x 45 x 13mm; the last two dimensions equating a AA's height & span. Can (& will, please) someone recommend a specific LiPo pack that'll fit that size compartment? And how do you hook it up? I could figure something out, but rather than cuttin' wires & soldering in a plug there might be a more convenient way that I don't know about - like some kind've adapter? Anyway, would appreciate some advice there. I'd like to retain ability to use AA's for a backup system if that's feasible.

Que?
A 3 cell lipo charges to 12.6 volts. I use a lipo in my Hitec Optic 6 that used to have a niMh battery of 9.6 volts that when charged would go close to 12v. I charge the lipo only to 12 v and its been fine for 3 years. Some people use a resistor or voltage regulator to drop the lipo voltage from 12.6 to 11 or so.
Last a very long time between charges.
2500GENE is offline Find More Posts by 2500GENE
Reply With Quote
Old Aug 21, 2011, 06:45 PM
Earthbound Skyhound
StarHopper44's Avatar
United States, NC, Richlands
Joined Jun 2011
5,046 Posts
Quote:
Originally Posted by khaled_abobakr View Post
Hi ..

Regarding the types of glue required to build the Bixler .. Please correct me

The body assembly

1-Medium Gap filling non foam CA
or
2-30 min epoxy

The CF Reinforcements

same as above or Gorilla glue

The Motor Mount

1-30 min Epoxy
0r
2-Silocon RTV
or
3-Hot glue
or
Plumber goop

Your input is greatly appreciated

Khaled
Not to dodge your question, but it would help to know what form of plane you bought - ARF, RTF, PnP, or Kit - for instance, in the RTF type the motor's already mounted so "none of the above" would apply.

Even with that I'm gonna leave it for the Pro's to answer your specifics -- for me it became "one of each" just so I could cover any need.
(pun intended)
StarHopper44 is offline Find More Posts by StarHopper44
RCG Plus Member
Reply With Quote
Old Aug 21, 2011, 06:59 PM
Earthbound Skyhound
StarHopper44's Avatar
United States, NC, Richlands
Joined Jun 2011
5,046 Posts
Quote:
Originally Posted by jrjr View Post
The energizers you refer to are 1.5v each. NIMH cells are 1.2v each. I take it that you mean you want to get a TX pack (transmitter) so you can recharge it. If you currently have 8 cells that equals 9.6 volts. 11.1v lipo may be pushing it voltage wise. Some people use them in place of 8 cell packs but Spektrum for one will not honor the warranty if they know about it. It works in some cases, some it doesn't. In my DX7 I made up a 2500mah NIMH pack and can run it for a looooong time between charges. Newer units may come with a lipo already. I don't know what your stock radio has as far as cell count or plug configuration so more info is needed.... and someone with the same radio may have a better perspective.
Tx is the Hobby King HK6DF, which exists in several profiles, this one just branded for HK & which comes with the RTF Bix. There's not even a mention of alternate power &/or any kind've other plug-in visible -- just a compartment for 8 AA's lying side by side with of course, series connection.

The User Manual (Haaaaa ha ha ha ha hahaaaaaa.....whee boy - I still can't get over that'n!) doesn't even tell you to put batteries in the darn thing - much less show ya where the battery compartment is!

(it's made in China)
StarHopper44 is offline Find More Posts by StarHopper44
RCG Plus Member
Reply With Quote
Old Aug 21, 2011, 07:35 PM
Gravity impaired
jrjr's Avatar
United States, NY, Wolcott
Joined Nov 2004
1,516 Posts
Quote:
Originally Posted by StarHopper44 View Post
Tx is the Hobby King HK6DF, which exists in several profiles, this one just branded for HK & which comes with the RTF Bix. There's not even a mention of alternate power &/or any kind've other plug-in visible -- just a compartment for 8 AA's lying side by side with of course, series connection.

The User Manual (Haaaaa ha ha ha ha hahaaaaaa.....whee boy - I still can't get over that'n!) doesn't even tell you to put batteries in the darn thing - much less show ya where the battery compartment is!

(it's made in China)
No specs eh? Figures. It may take a 3s lipo with no trouble if it was set up for 8-1.5v cells originally. Worst case you could velcro the lipo on the back of the transmitter and make a cord with a plug sticking out of the battery compartment.

OR you could get 8 nimh cells and a charger that charges individual cells and insert them in the compartment as is.

Charger

Cells

I have had great luck with Tenergy cells
jrjr is offline Find More Posts by jrjr
Reply With Quote
Old Aug 21, 2011, 07:52 PM
There's magic in those wings !
khaled_abobakr's Avatar
Joined Nov 2006
4,819 Posts
Quote:
Originally Posted by StarHopper44 View Post
Not to dodge your question, but it would help to know what form of plane you bought - ARF, RTF, PnP, or Kit - for instance, in the RTF type the motor's already mounted so "none of the above" would apply.

Even with that I'm gonna leave it for the Pro's to answer your specifics -- for me it became "one of each" just so I could cover any need.
(pun intended)
... Sorry I forgot to mention.. it's a Bixler in Kit version ..

Khaled
khaled_abobakr is offline Find More Posts by khaled_abobakr
Reply With Quote
Old Aug 21, 2011, 09:01 PM
Earthbound Skyhound
StarHopper44's Avatar
United States, NC, Richlands
Joined Jun 2011
5,046 Posts
Quote:
Originally Posted by 2500GENE View Post
... Flying past the LVC warning is never a good idea and the fact we're even discussing it is ridiculous.
Nobody's disagreeing with it not being a good idea - not me anyway. What we're talking about is conditions where you might be dangerously near the LVC without knowing it....and workarounds to avoid it. At least, me anyway. I don't have the experience to know all these things or to've figured them out yet....that's why I asked.

And if that's ridiculous to be discussing, could someone please point me to a forum for dumbasses that want to learn, & you don't have to ask questions that make everybody happy?
StarHopper44 is offline Find More Posts by StarHopper44
RCG Plus Member
Reply With Quote
Old Aug 21, 2011, 09:20 PM
Registered User
West Texas USA
Joined Mar 2008
662 Posts
Quote:
Regarding the types of glue required to build the Bixler .. Please correct me
I built a Sky Surfer V2 with the stock brushless outrunner motor.

Glues Used:

Body and spar covers and tail: CA.

Motor: Hot glue to tack the spacer and motor in place. Then Gorilla Glue to finish.

For any other mods using carbon fibre I generally use CA.

I fixed the servos into the wings and fuselage using hot glue.

There are many adhesive solutions out there that will work, I believe.
garymcc is offline Find More Posts by garymcc
Reply With Quote
Old Aug 21, 2011, 09:22 PM
Registered User
Chilliwack, BC Canada
Joined Mar 2010
1,092 Posts
Quote:
Originally Posted by StarHopper44 View Post
I's talking about the ones we get - like the HK6DF Tx/Rf combo, & stock-or-close-replacement servos.

I'll go ahead & reveal:
We "know" when it's time to land from when the motor goes soft, right? BEC insures there's juice to land if we're 'overdrawn'.

Say you get some thermal action & are up there a long time. No motor to 'feel'. How long does it take the Rx & Servos to eat up the precious amps in that last 3 volts?? Seems that could produce some seriously unpleasant results. ?????
I don't think the RX and servos are going to flatten the battery, even to the point of browning out your receiver, in the time you are likely to be flying with a dead motor. That battery is still at about 9 volts. Your receiver doesn't need but about 5 volts. I checked my SS with a little gadget called a Servo Sense Plus from Dimension Engineering (unfortunately no longer made). It plugs in between the ESC and the receiver and measures current (max, average and average over 15 seconds). Stirring the sticks all at once got a maximum of 1.3 amp and an average of .2 amp, RX and servos together. This was not flying, but I wouldn't think it would be that much higher in gliding flight. I will put the Servo Sense in the plane the next time I fly it to see just how much more current is drawn in easy flight. Then I will do it again and flog it for a while. Should be interesting! Don't know why I didn't think to do this already.

Gord

Woo hoo! Well Dimension doesn't sell it any more, but I think they are still making it for Common Sense RC. They have it under a different name. http://www.commonsenserc.com/product...oducts_id=1464
Gordks is offline Find More Posts by Gordks
Last edited by Gordks; Aug 21, 2011 at 09:29 PM. Reason: Source for a 'servo sense' device.
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale Cyber Sky Parachute (Sky Surfer) shv2sail Aircraft - Electric - Airplanes (FS/W) 6 May 28, 2013 02:14 AM
Discussion Sky Surfer nickwayne11c Electric Plane Talk 15 Nov 18, 2011 02:36 PM
Discussion Banana Hobby Sky Surfer Problems cavy92 Electric Plane Talk 56 Nov 02, 2010 02:49 AM
Question Sky Surfer LiPo mod, help... Freight Dog Power Systems 0 Aug 17, 2006 01:45 PM
Swashplate Assembly with Center Ball; is this the swash with ball mod i want? tekforce Micro Helis 4 Feb 08, 2004 05:28 PM