PDA

View Full Version : Converting an Air Core 40 Trainer


ictbu
08-06-2006, 04:39 PM
Has anyone ever converted an Aircore 40 trainer to Electric? I am just starting the build and am considering a conversion. I have a few electrics but have never attempted a conversion. Anyone familiar with Aircore Kits will know that they have a power cartridge that comes on and off. I'm having a hard time visualing how I would alter that setup to allow for electric. Any knowledge or input you can give would be appreciated.

Thanks

Darin

ragbag
08-08-2006, 06:56 AM
Funny you should bring this up now.

I just traded a NIB Aircore for a three GWS kits and a Gentle lady glidder. Barked out anothe Aircore and set the hull out at the field, free to a good home. Didn't lat overnight.

The used one had seen better days, but still serviceable.

The power pod would make it very easy to setup for electric, didn't think of it for the kit, might have considered it.

I would consider one of the larger Axi's since that is my motor of choice usualy. Probably opto ESC or disconnect the power lead from the ESC to the reciever since I would be using full size servos and need the reciever battery to make it easier to set up. I don't think the smaller servos would hold up on this craft, eve with metal gears.

Maybe put the elevator and rudder servo on their own board to make it easier to shift the power pod for trimming purposes. The power pod slides in a channel in the fuselage, so a smaller pod with the said servos could slide in ahead of the power pod. Then the power pod with the batteries could be used for the final trim setup.

MY two cents worth.



.:)

foxtestpilot
10-12-2007, 06:41 AM
that sounds like a project....i would think the weight would be lower withe the electric set up id try zipties...im a nitro guy turned foamie but used zippies on them all fast and painless...lol let me know how it turns out

Fishbonez
12-02-2014, 02:41 PM
Well I know this is a very old thread, However I just attempted to convert an AirCore 40 and here was the maiden.
5KhuLdYJ43Y


https://www.youtube.com/watch?v=5KhuLdYJ43Y

I am looking for some suggestions here. Could it be a thrust angle problem or maybe a stall because of lack of speed? It did take off the ground before I thought it would. Tail heavy? I balanced it as per the manual at the spar. I also built the kit as per instructions to include power pod. Motor was mounted on top of the wood provided for the engine. with a block of balsa as motor mount. I added no thrust angle only because the manual stated that none was needed. I know I probably should of added some but...
My set up is as follows:
Sky Power 60A ESC with Switchmode BEC
APC 11 x 7E Composite Propeller
Power Up 32 Sport Outrunner Brushless Motor
4S 3300 Battery

This is my first kit and my first conversion so any thought anyone may have will be appreciated
Thanks

Turner
12-02-2014, 05:54 PM
Definitely a lack of airspeed but it also looked tail heavy. Many glow conversions like this wind up tail heavy. I thought I heard some wind too. That might not have helped if it was blowing and gusting.

Fishbonez
12-02-2014, 06:26 PM
Definitely a lack of airspeed but it also looked tail heavy. Many glow conversions like this wind up tail heavy. I thought I heard some wind too. That might not have helped if it was blowing and gusting.

Thanks Turner, I agree with lack of airspeed. I was unsure how long it would take this plane to get to speed and lift off. I have been known to make that mistake before. There was some wind and it did gust a bit. Wind was from 10-15 mph a typical Wyoming day :) A slight breeze for us for this time of year especially in the winter time this is definitely our windy season :cool: The more I look at the video I think I have a combination of all 3

Slowjohn
12-03-2014, 01:30 PM
Hey FB,
What's the AUW of the plane?

For some reason I keep getting an "Error Occurred" message on the video.
Have you checked the wing to H-stab incidence?

Standing By,
SJ

Fishbonez
12-03-2014, 04:13 PM
Thanks SJ,
Unfortunately I do not know the weight. I really do need to buy a scale to weigh my planes, One of those things I never think about when I am out and about. Also no I have no checked the wing to H Stab incidence since I built the model based on instructions, this is my first kit, I did not think to check that. I shall do that this afternoon. I shall hopefully have some answers for you buy then.

Also I am not sure why you are getting an error message but just for kicks and giggles here is the link:
https://www.youtube.com/watch?v=5KhuLdYJ43Y

Slowjohn
12-03-2014, 04:41 PM
Still get the dreaded "Error" message ::o It'll download for close to a minute and then the error message pops up & the download stops. Probably on my end.

Another thing to look at if everything else checks out is the supplied eng. mount. I suspect it has the thrust angles built into it instead of the firewall but since I haven't built that kit I'm just guessing. If it was wanting to climb hard at 3/4 to full power then I'd add down thrust, maybe 2 washers. If it kept wanting to turn left add a washer (or two if needed) to the port side of the motor mount. Again since I can't view the video... Good Luck!

Standing By,
SJ

solentlife
12-03-2014, 06:52 PM
FB .. sorry to say it was a typical hold up elevator and lift off far too early ... the cartwheel to left is typical torque reaction at dead slow speed. When watching video - the tell-tale signs are :

a) The tail never lifts so fuselage levels out before lift ... she stays at 3 pointer angle to ground throughout.
b) Short distance to lift off.
c) Nose rearing up under influence of prop pulling her ... elevator pitching up.
d) The standard torque out to left ... once speed has dropped so far all that is left is torque reaction.

Trouble is once you do that - it's very hard to say tail heavy or not because the model is already nose high - stalled and going to cartwheel EVEN if it's nose heavy ............. basically she's doomed the moment she left the ground TOO EARLY..... TOO SLOW.

My Cub does exactly same if I'm not careful .. I have to ease the throttle in ... keep her on ground ... let her build speed and then lift literally just edge her up ...

I appreciate this is a trainer and should be able to suffer hauling of ... BUT shes lighter than a fuel job I suspect ... gear is moved more forward to get balance ... so the moment arms are all different to a fuel set-up. It's not just a matter of CoG in right position .. its also about weight distribution to achieve it.

My suggestion ? Put her back together ... CoG at recc'd point ....

Ease the throttle open .. keeping her tracking on ground till SHE shows she wants to lift and fly ... ease the elevator ... so she adopts a gentle climb out ... building speed all the time.

I repeat - to me - that was a classic haul of deck too slow and too hard ... go on Youtube ... zillions of similar posted there ... handlaunches .. RoG ... all slow and haul up - left wing over - BHAM !

All above based on your hand on heart that build was as per book ... ;) I believe you. Honest.

Cheers
Nigel

Slowjohn
12-03-2014, 07:35 PM
Thanks for explaining what the video showed Nigel. Reading your explanation it is truly what I think happened with my Special Twin build on it's maiden. When I tried to just lift the nose to avoid any more prop strikes it jumped into the air and just wallowed thru the air for 1/2 a circuit around the field never gaining altitude. Thing is I knew everything was right on it & I used Counter-Rotating props. Only thing I did wrong IMHO is I was in a hurry to maiden it and I didn't wait to order new 4s lipos for it so I used some 4000mAh 3s lipos which of course reduced my thrust to just over 1:1. So it sounds like you probably nailed it. I'm still curious about the items I suggested he check & like I said, I was only guessing since it was his first kit build plus my not being able to view the video...

Standing By,
SJ

solentlife
12-03-2014, 08:13 PM
Nice to see you posting SJ .. you're part of the furniture round WF !! We 'aint letting you go yet !!

OK - there's no g'tee I'm right .. It just follows that same old slow haul up pattern we see again and again .. No disrespect FB ..

I reckon she'll fly set up as book - just don't haul her up .. maybe even put a few clicks of down in to avoid the UP syndrome ?

The video was as you - Error when I tried to play - but then it just upped and played ... I put cursor back to start and watched it 3x .. even slowed it as I do my own when doing diagnostics ...

The vids I have real trouble with are Vimeo's .... they may be great for you guys - but over here - I dunno - spoke to others I fly with ... some reckon if they see Vimeo - they don't bother to try view.

Nigel

Fishbonez
12-06-2014, 08:26 AM
Small update,
After taking all advice from here and other sites. I repaired the Aircore added a touch of nose weight and some down thrust and here was the results. She really needs a lot of trim wanted to go right and could not get her in trim she also still wants to climb so will need to do some more trimming there as well. I did lose all left aileron and it did not seem to respond to rudder. I then tried to move right but she began to get away from me and while attempting to turn right again she stalled and down she went.

JBN6pLAxZqM

http://youtu.be/JBN6pLAxZqM

Still have a long ways to go but we are getting there

solentlife
12-06-2014, 09:06 AM
Well ... that's an improvement BUT !!

OK - just an observation ... that is one hell of a straight wing for a trainer plane. Is there any dihedral there ?

I know this sounds daft to some - but a high-winger like that would benefit from even cosmetic dihedral .. it would help in stability and also ability of rudder to help you out.

She seemed to show still a RIGHT aileron tendency on take off as in video 1 .. but luckily this time - she had more speed and didn't go into the left drop, wing stall, torque cartwheel. She flies.

So what is needed ? Maybe you have too much authority in ailerons causing adverse or stalled condition ... flat wing does not always help.
Maybe she needs to slow down a bit in flight...

She's going to be hard to nail down - but often a simple tweak and bingo !

Now this may sound daft ... Oh here he goes again !! ............. what prop are you using ? What motor / kv / lipo ?
Wondering if reducing prop torque could help ? I have models like my J3 that are defiinitely over-torqued ... my SE5 will do a kangaroo waltz because of it ...

mmmmmmmmmmmmmmmm thinking caps on !!

WE WILL GET TO BOTTOM OF THIS !!

Nigel

Slowjohn
12-06-2014, 01:41 PM
FB,
Did you check for any twist or warpage in the wing?

Standing By,
SJ

Fishbonez
12-06-2014, 03:11 PM
Well ... that's an improvement BUT !!
so true. We are going to get there. I gotta admit I am enjoying this challenge

OK - just an observation ... that is one hell of a straight wing for a trainer plane. Is there any dihedral there ?


I know this sounds daft to some - but a high-winger like that would benefit from even cosmetic dihedral .. it would help in stability and also ability of rudder to help you out.[/QUOTE]
I agree I was thinking as I was doing the build for a trainer there is no dihedral in this wing. As far as adding some I am not sure the spar is made of balsa and the rest is pretty much coreplastic ribs, what few there were in it

Now this may sound daft ... Oh here he goes again !! ............. what prop are you using ? What motor / kv / lipo ?
Wondering if reducing prop torque could help ?
Not daft at all here is my current setup:
Sky Power 60A ESC with Switchmode BEC
APC 11 x 7E Composite Propeller
Power Up 32 Sport Outrunner 800 KV Brushless Motor
4S 3300 Battery

Fishbonez
12-06-2014, 03:23 PM
FB,
Did you check for any twist or warpage in the wing?

Standing By,
SJ
Well I did on first attempt and it seemed ok. However on this attempt I did not look to close. The fortunate thing is during crash inspection the wing came unglued so if there is some warpage I think I can fix it as I repair wing. I also thought maybe wing was not balanced either which might explain why on takeoff she tipped. I also wonder if it was a slight torque roll problem. Like Nigel mentioned I maybe overpropped

Hey FB,
What's the AUW of the plan
For some reason I keep getting an "Error Occurred" message on the video.
Have you checked the wing to H-stab incidence?

Standing By,
SJ

Unfortunately SJ,
I still don't have a scale. I think I will need one for this project. I also think I will need a good angle meter to check the incidence properly. The ole calibrated eye method may bot be so good :D However all kidding aside I checked to see if it was "in straight line" with wing to the prop and well it seemed good. Again I was using a straight edge and not proper tool for the job

Slowjohn
12-06-2014, 05:35 PM
I still can Not get the video to play. It'll load but won't play now :mad:
The wing needs to be checked for alignment at the rudder or leading edge of the H-stab at the fuselage out to the wing tips or some other reference point you chose. Visually look down the fuselage to the H-stab to check to see if it's all in line or you can measure from the tips to your work table.
Good luck with the re-build.

Standing By,
SJ

solentlife
12-06-2014, 06:06 PM
Scales ... straight edge .....

The remarkable thing is the human eye. It is incredible at detecting a deviation in a line. Stand back and view an item as a whole ... unless there are other lines / objects to distract the visual reference - you can see quite small deviations from the straight line.

Eyeballing a model is more accurate than a lot give it credit for ...

BUT there are exceptions where form can distort the eyes evaluation.

The HK Edge 540 racer ... - to eyeball the stab and elevators is actually not so absolute. Te eye is tricked by the aerodynamic shape of the stab and elevators and in my checking of my own model - resulted in a slight down offset of the elevators. Placing a straight edge along the centre line LE to TE showed the slight error. Why would this happen ? The form appears to be symmetrical and the eye assumes the straightness. But in fact mould or whatever is not exact and the eye is deceived.


There's another trick that is old as the hills ... the close and open eye .. swapping one eye for other and back and both together in a sequence. This shows up any offsets on rudder etc. as the image jumps side to side and then both eyes try to centre it ... needs practice - but works.
Anyway .. eyeball at a distance ... as SJ advises ..