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Old Apr 20, 2012, 02:33 AM
How close are those trees?
Goody63's Avatar
Perth, Western Australia
Joined Apr 2008
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Lipos in series

I always thought that when you ran lipos in series they were suppose to match each other (otherwise one could drain before the other etc - maybe I'm getting confused with parallel setups ).

Anyway I've noticed that Dionysus (and probably a few others) run a mix of lipo capacities in series.

Obviously then this is ok to do but I was just wondering what the golden rules are?

Must be same brand and C (discharge) etc?

I've already got a couple of 3000MAH 6S's so was thinking that instead of running them in series (cos of the combined weight) I could just get a 1500 to 2000 6S to use with a 3000 in series?

Thanks for any advice.

Cheers
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Old Apr 20, 2012, 05:30 AM
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McQueeney TX
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For a series set up the batteries have to be the same C and mAh. The 3s and 5s I run in my f-100 discharge equally.
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Old Apr 20, 2012, 08:27 AM
How close are those trees?
Goody63's Avatar
Perth, Western Australia
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Quote:
Originally Posted by Dionysus View Post
For a series set up the batteries have to be the same C and mAh. The 3s and 5s I run in my f-100 discharge equally.
Sorry.

Yep I did have my wires crossed. Your running them in parallel.

Cheers

Dave
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Old Apr 21, 2012, 03:29 PM
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United States, TX, Grand Prairie
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NOTICE

If you think you're going to be going 120-140ish in this plane use thicker rods in the elevators with metal control arms.

Deep dive at 9.5lbs of thrust full throttle slight left turn for a little knife edge and nosed in hard. Really surprised with the lack of damage to electronics.. EPO saved the batteries and 12 blade CS fan is fine and so is the wing but the right horizontal stab arm just broke in two most likely from flutter.

Thank goodness HK still has them in stock but shipping price went up 17usd

Anyone know what to use on elevators for this plane for fast speed please give suggestion

I don't think people who designed it thought it'd be going that fast....I sure didn't, seemed like it was somewhat draggy but that T4074 - 1400kv and cs fan on 8s scooted it off the run way in 75 feet really nice priced and performing power system.
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Old Apr 21, 2012, 04:41 PM
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Canada, ON, Burlington
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erh
What "right control arm" are you talking about, the ailerons or stabilizers?
The control horns supplied with FF or HTG are generally too flimsy IMHO. I used regular control horns embedded into each aileron (and the rudder) glued with PU glue. The stabilizer control setup seems pretty sound. The only weakness I see is the stabilizers themselves. Very flexible foam (until I added CF strips along the TE).
Not a chance of doing much over 100mph on my 6S setup anyway...
Cheers Eric
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Old Apr 21, 2012, 06:38 PM
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United States, TX, Grand Prairie
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Quote:
Originally Posted by 4stripes View Post
erh
What "right control arm" are you talking about, the ailerons or stabilizers?.
Stabs

Quote:
The control horns supplied with FF or HTG are generally too flimsy IMHO.
You're right, I should've had an idea that I was going to be pushing it with this fan...after talking to some club members it was no doubt doing over 120 coming out of the dive...looked really good too.

Such is our hobby, another on it's way and I'll be reinforcing the stabs with CF of clear packing tape (something that works real well if you can get the seams right) and using metal control horns.
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Old Apr 21, 2012, 07:17 PM
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Too bad about your loss but you have the right attitude building a better second one!
When I mounted the stabilizer control "arms" (bolts into wheel collars), I made sure the bolt ends were 100% flat to mate with a notch filed into the stabilizer torque rod. This style "arm" is used in the Starmax F-16 and gave me some trouble until the bolts were filed square. Without filing, the bolt will not sit tight enough to counter the strong twisting forces. The stab will twist out of proper position if the bolt doesn't sit "flat" on the torque rod.
Cheers Eric

PS My F-16 was almost lost pulling out of a dive because one stab would "blow back' causing a roll instead of a clean pullout. Perhaps this happened on your last flight.

I later crashed my F-16 when a LE flap linkage buckled at high speed. When the second was built I simply added CF tubing over any linkage wires that might suffer bending forces.
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Old Apr 21, 2012, 07:50 PM
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From your description it sounds like you might have lost control due to a non responsive flight control - what were you powering your stabs and rudder with? You could have over powered your servos at those speeds, gotten some flutter/buzz or...

As far as the engineering on this model, one of the biggest weak points on the F-100 as designed only becomes an issue when the model is over powered of course. But the weakest area IMHO is the stabilizer MOUNT - in other words, the way the black plastic stabilizer bearing pivot part is actually attached to the foam airframe itself. It is clearly a high stress point and foam is not rigid or strong enough to hold it securely at high speed and increased weight if one expects to fly aggressively. Even if using a 2" lead pipe for a stabilizer pivot rod and using a solid piece of titanium for the servo arm and connecting rod, the stabilizer itself will fail along with the plastic bearing structure as the foam will not be able to hold it in place. That area has to be backed up, to mount into the foam with extra support (like wood spars, glass, etc - much in the same way we tend to beef up our retract mounts in the wings).

Assuming the aft fuse is appropriately beefed up structurally at the mount area, some have had good success using brass tube that carries through the whole thrust tube area to both the stabs. For me, I upgraded the fuese mount area for the stab pivot bearing but also - I am using the stock plastic mount but I've upgraded to quality 3mm hex head screws for the pivot mount attach point, upgraded hardware mount and I've sheathed a new 2mm pushrod in carbon tube to the servo. I've mounted the servo forward of the stabs under the fuse to take advantage of more structure for a much more rigid servo mount area. If you look at my build blog on the F-100 I have ll the pics there. I have not updated the photo stream yet, I'll put more on next week when I have time. I'm not planning on more than 110 mph with the model but I've still felt the need to upgrade the stab area due to the very marginal stock design.

Sorry to hear about the mishap. Do you have any photos to show where the stress damage occurred in the stabilizer area? (I'm not talking about the general airframe, I'm sure that looks like mashed potatoes and corn bread).
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Old Apr 21, 2012, 08:34 PM
When the time is right
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Hayward, CA
Joined Apr 2001
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erh , I like your style man , Over power then over speed , rebuild , repeat wish I could afford it . I am certain you will find and address any weak spots. ( what am I thinking , it is a weak spot ,it's foam ) Anyway , ditto on the call for pix , the beauty of the scale details was blinding me , "mashed taters n' cornbread " OK with me.

Earl
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Old Apr 21, 2012, 10:05 PM
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United States, TX, Grand Prairie
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Anyone know how to decompress EPO?

I looked at the fuse and it split down the middle and compressed at the top but the heat of the car maybe is helping it decompress some of the smaller creases. I prolly could press some of it out and no one would tell the difference if I could sand some of it and repaint.

Will take a pic this sunday if I have the time, the fuse broke clean, the wings are fine the tail is fine.. no doubt will keep it as a back up

The second is 144 shipped from HK to my location so for this kit I don't think that's a lot...at the fly in everyone put their models up to watch it fly and said they liked the turbine sound..

I call this a hanger plane cause of the overall flight cost is low, great looking model that can be scaled (thx dionsys) and it can fly fast....man it was moving.
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Old Apr 21, 2012, 10:28 PM
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Quote:
Originally Posted by 4stripes View Post
...PS My F-16 was almost lost pulling out of a dive because one stab would "blow back' causing a roll instead of a clean pullout. Perhaps this happened on your last flight...
This is exactly what happened...I prolly made it worse by giving some up elevator.

Thx on the elevator reinforcement tips, I'm even thinking of sheeting them after doing the brass tubing and some wood inserts like stabs on my bigger jets.

Once you go that fast in this jet it's hard to go back,...and come to think of it we had a 15mph wind minimum from the north so the airspeed was prolly higher IINM...yeah, that would do it....I was diving down north bound to do a slight left bank then I was going to go vertical to split S so I could catch the extra speed with a tail wind and I lost control in the beginning of the pull out where the plastic control arm broke right in the middle of the arm.

I'll prolly have mine rebuilt with the reinforcements before WACO if Dionysis is going to be there, we can do some HUN formation flying...there will no doubt be pics of these two models knock on wood on both of us making it.
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Old Apr 22, 2012, 03:10 AM
How close are those trees?
Goody63's Avatar
Perth, Western Australia
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Quote:
Originally Posted by erh7771 View Post
Anyone know how to decompress EPO?
I've had a lot of success with either holding the parts under running hot water (or boiling water) or holding them over steam (from a kettle or boiling pot).

Some people dip the parts into boiling water but I've never gone that far.

The EPO will blister a little on the surface but you can smooth these out with the back of a desert spoon whilst the foam is still warm.

More info in this video below;

Repairing EPO foam with boiling water.mpg (7 min 51 sec)
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Old Apr 22, 2012, 03:26 AM
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South Africa, GP, Pretoria
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erH,

Never good when this happens. I do not have a lot of faith in the full moving stab at high speed. Initially my Hawk had the full moving stab but converted it to fixed and cut out the elavator at the end. I mounted the servos in the elavator the same way as the stock F86. I know it is not as impressive as the full moving stab, but when in the air you cannot see any difference and gives peace of mind.
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Old Apr 22, 2012, 06:36 AM
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McQueeney TX
Joined Oct 2005
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I've been racking up the flights with mine, I think the stock stabs are fine, at least they are working for me. They are well designed, meaning the pivot point is in the correct location for a full flying stab. I'll be going over 100 high speed flights here real soon!

Quote:
I'll prolly have mine rebuilt with the reinforcements before WACO if Dionysis is going to be there, we can do some HUN formation flying...there will no doubt be pics of these two models knock on wood on both of us making it.
I am planning on being at the Greater Southwest Jet Rally in September, not sure what days yet or if I'll stay for the whole thing. Will have my turbine Bobcat and maybe one other turbine jet along with my EDF's. See you there!
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Old Apr 22, 2012, 06:05 PM
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Quote:
Originally Posted by goody63 View Post
i've had a lot of success with either holding the parts under running hot water (or boiling water) or holding them over steam (from a kettle or boiling pot).

Some people dip the parts into boiling water but i've never gone that far.

The epo will blister a little on the surface but you can smooth these out with the back of a desert spoon whilst the foam is still warm.

More info in this video below;

http://www.youtube.com/watch?v=rhasr...eature=related
thx!
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