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May 12, 2004, 11:36 AM
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PaulSwany's Avatar
I'd still like to mount the ESC in the wing... Would really clean things up....
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May 25, 2004, 10:59 PM
And You're Not
Some pics of a radically altered E FF Taco. AUW 25 oz.

Lehner 1020/15 Phoenix 35
Cobri aluminum gearbox 12 tooth SS pinion, 70 tooth spur
12X6 APC SF prop
Tanic 3S 2600
Berg 5
4 X Dymond D200 Servos.

It was an amazing combo, lost to a midair on it's first evening out.
May 26, 2004, 09:33 AM
Registered User
Jeffery,
Thanks for sharing! That does sound like an impressive version of the Taco! Sorry to hear it was lost so soon. Hope all the expensive bits survived. Will you be doing another one? Care to expand on the "radically altered" aspects, especially in light of a 25oz AUW? What was the WOT static current in that system? Bet that Lehner system is sweeeet.

Brad
May 26, 2004, 10:27 AM
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PaulSwany's Avatar
I like Jeff's modifications soo much, I'm going to incorporate them into the ETaco kit.... Great flying bird for sure!
May 26, 2004, 10:32 AM
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Jim T. Graham's Avatar
Man those birds look great. I like the Kokam red lightening bolt trim scheme.
May 26, 2004, 10:48 AM
And You're Not
Yeah, I have a few pics from when I built this one. Luckily (if there is such a thing ) the mid-air happened at Paul Swanson's home field. He was able to take a lot of notes and dimensions off the wreckage and is going to implement some of them into an E Taco build addenda to the Fat Free Taco.

I actually built this one in near secrecy to surprise Paul at his fly in. I maidened it the evening before the event, it was lost later that same evening. But it had enough flights on it to demonstrate that it was a killer plane. Not just so-so, but over the top.

The Lehner as I had it set up drew 32.5 amps static. A little high, but I have to say that WOT throttle was not needed except on a punch out to make jaws drop. Flying around in normal 3D mode was very easy on the set up. We played pass the TX on 3 packs and all of them were about 1.7 Ah out of 2.6 Ah used, probably 15 minutes or so per pack, just guessing. Nothing even more than coffee cup warm after a flight.

I had a 74 tooth and 78 tooth spur drop shipped to Memphis to try, but never got to try them after the mid-air. In retrospect, I am pretty happy with the 70 tooth in draw and performance. I was not sure how much throttle would be needed to fly and was kinda worried I might melt stuff, but this is one set up that you really could not use WOT for more than 2 or 3 seconds max. It moved out.

Some of the things I changed:

No wing sheeting on the LE, TE, Cap Strips, or center section.

No hatches.

CF tape on spars, only vertical grain shear webs on first bay.
CF tube replaced FG rod.

Ply motor mount deleted, motor stick on CF tube instead.

Bottom fuse piece replaced with balsa stick truss, CF tape reinforced.

Dremel drum sanded the ID of all the Fuse Top, Elevator LE, Rudder LE and Bottom, Aileron LE replaced with 1/4" stock.

Used contest grade 1/4" balsa for all of the fuse front (Top and Bottom pieces), all of the 1/4" sq sticks were ripped from contest balsa.

I added a set of 3/16" sq sub-spars near the wing TE to make it a little stiffer since I left the TE sheeting off.

That's all I can think of right off hand. I will say this was one sweet plane, you bet I'll build another.

A point I want to make....this was not just a Glow> Electric conversion that worked, a novelty to say I did it. This was an incredible plane, not just on par with the glow planes at the event, but actually head and shoulders above just about anything there (106 planes were counted on the flightline Saturday, 45 registered pilots, all 3D flyers). I would have liked to have entered in the verical drags, I don't think there was but a couple of planes that could have given me a run for my money.

So stay tuned, there will be more installments of the E Taco coming, Paul has a real winner that can be E-Modded quite easily to a spectacular result.
May 26, 2004, 11:44 AM
And You're Not

Pics


These are the pics I took, not so much a build sequence, just kinda hitting the high spots..




















The GWS box was replaced by this:



Last edited by Jeffery; May 26, 2004 at 12:55 PM.
May 26, 2004, 11:50 AM
Registered User
Jeffery,
Thanks for the details...I may have to build another Taco now that you've paved the way for a substantially lightened version.
Quote:
I would have liked to have entered in the verical drags, I don't think there was but a couple of planes that could have given me a run for my money.
Bet you're right, with power/weight numbers like those passing through that efficient deeply geared Lehner system.

Hope you don't mind me pestering you with a few more questions...

Was the 32.5A WOT static current measured with a fully charged battery? The WOT current seems a little high for a 4000 Kv motor on 3S Li-P with 5.83:1 gearing and a 12X6SF prop. Do you recall the timing advance setting on your PHX-35?

With no hatches, where did you mount the receiver, ESC, and battery? What was your CG location?

Paul,
Do you plan on kitting an E-taco with these mods and the necessary materials, or just providing the instructions for the builder to make these mods using his own materials?

Brad
May 26, 2004, 12:44 PM
And You're Not
Brad, I never got around to programming the PH 35..so whatever the default is. I do wonder if I'm remembering the readings taken from the 5.5:1 GWS box. It was on a fresh off the charger pack. I can check this evening, the expensive bits survived

The ESC was wire tied to the bottom of the LE of the wing, I put a small balsa shelf between the LE sub-spar and the main spar with holes for zip ties, put the zip ties in before I covered the top of the wing.

The RX was Velcro'd to the servo rails between the servos on the side opposite the ESC to help lateral balance.

The CG was about an inch behind the spar, I was worried about being tail heavy, but it flew perfect there.

The battery was mounted in a slot in the lower fuse, secured by rubberbands connected to dowels. This had not been added yet in the above pics. That part of the plane is intact, I can post pics of it.

Then I mounted the gear box "upside down" so the weight of the motor would help offset the weight of the battery in top/bottom balance.

Here is a not-so-great pic of the bottom..you can just make out the ESC on the right side (as viewed) and can almost make out the RX on the far side..the bunch of wires between the servos on the far side.

Oh, and a pic of Moderator Ulf Rieder as an added bonus!!

Last edited by Jeffery; May 26, 2004 at 12:50 PM.
May 26, 2004, 04:16 PM
And You're Not
Quote:
Originally Posted by Brad S
Was the 32.5A WOT static current measured with a fully charged battery? The WOT current seems a little high for a 4000 Kv motor on 3S Li-P with 5.83:1 gearing and a 12X6SF prop. Do you recall the timing advance setting on your PHX-35?
I remember posting in Post #38 of This Thread the amp draw, and it was indeed 32.5A with the 5.83:1 ratio, but also that there was no RPM gain in the last couple of amps, just heat.

I can only guess that when the prop unloads in flight that the current drops off, or the RPM goes up (both??) since it has extraordinary thrust at lift off. Hopefully, the next one will last long enough for a gear change and in-flight side by side comparison of a couple of different ratios.

As a side note... B-P-P usually has a waiting list for the 1020/15, but almost always shows the 1020/14 in stock. It is a 4290 KV or so version, but wasn't as popular due to the restrictive selection of GWS ratios, and the fact that a 12 tooth pinion is the smallest that can be mounted on the 1/8" shaft of the Lehner.

Now with the wide selection of ratios offered with the Cobri box, one could buy a /14 and gear it a little deeper to approximate the performance of the /15 at 5.83:1....just a thought.
May 26, 2004, 06:09 PM
Registered User
Wow Jeffery! You really thought out and addressed all the details of this conversion in spades! You did a fantastic job and I'll bet that the first flight delivered a huge smile!

That Cobri gb looks to be a great choice for 3D aircraft in this size range. With the deeper gearing available, the Lehner 1020/14 should work fine. While not quite as efficient and light as the Lehner, something like the Mega 16/15/3, or even the 4600 Kv 16/15/2 would probably work well for a "radically altered" Taco using a 28mm version of the high-ratio capable Cobri gb.

The only part of the whole thing that is a little unsettling is the prop. Didn't it make you a little nervous to be in close proximity of a 12" slow-fly prop that spins >6500 RPM at full throttle?

Brad
May 26, 2004, 06:42 PM
And You're Not
I had a 12X6 E prop, but it just didn't pull very hard static. Since most of the flight is in the low RPM realm, I wasn't really thinking of prop failure, just thrust.

Not sure what the max RPM of a SF is, but it is still together after all of that.

And you can't imagine how happy I was after the first flight. I had worked night and day to get it air worthy before the event, not knowing if it was going to be worth a hoot. Then drove 10+ hours to get there, still without a maiden. I knew when I hit the throttle I had it made, and after it was trimmed, I was very, very pleased. The CG issue had me pretty concerned, but I was set in stone unless I wanted to add weight, or maybe run CF pushrods for tail lighteners.

With 7.5 oz/ ft^ wing loading, everybody said it flew like a foamy

This was my first E conversion and I had nothing to really judge it by. The Lehner 1020/15 seemed to be a hot ticket for an Attitude, and the Taco is just a little bigger. I was obsessed with keeping the weight down, I was shooting for 24 oz. And I almost made it!

I think the big difference, and I told Troy at B-P-P this...I was determined to run a 12" diameter prop for the extra thrust. I probably wouldn't have been able to if it hadn't been for E-Flightline announcing the Cobri box on Friday morning, exactly a week before the intended maiden. I was on the phone as soon as they opened and got a couple shipped ASAP so I'd be sure to have one in time. Got them Monday

So everything came together just right. I wish my covering scheme was a little more imaginative, but it was my first try with Solite and I didn't try to get too carried away. And at that time, I didn't know it was going to be so awesome. The next one will hopefully be a little more pleasing to look at.
May 26, 2004, 10:13 PM
I hole jumped him!!!
Lance's Avatar
Fantastic job (as usual) from you, Jeff. It was bittersweet that I had the unfortunate luck of finding a job recently, thus preventing me from making the Memphis event. I'll pencil it on the calender for next year....we can take my Pimpxpedition and put your Bling Bling! pt.2 E-taco in the back. By then I'll have my own E-Taco I'm sure, and I'll have your old Cougar 2000 E-powered by then (hopefully).

Hey, if the wind lays down then maybe we can get some flying in this weekend. Meet in Amarillo again.

Ya know, you could parallel a couple of your 830 packs together and they'd probably feed the lehner just enough to live under short bursts, and you'd make your magic 24oz weight. I pulled 22amps for a couple of seconds on an 1100mah irate pack on my "foamie that got away" last week.

Ok, gotta email Troy at BPP. Must have another lehner.

Lance
May 27, 2004, 10:12 AM
Registered User
Quote:
Not sure what the max RPM of a SF is, but it is still together after all of that.
Here's a link to APC's suggested limits.
RPM limits
The relatively wide blades of the SF props always deliver more thrust and draw more current than the equivalent sized E props. Even a 13X6.5E will probably draw a little less than a 12X6SF. If you've got the prop clearance, you could probably go up to a 14X7E with a little deeper gearing. I had to add 1" to the LG wire lengths to (barely) clear the 14" prop on my Taco.

Brad
May 27, 2004, 10:26 AM
And You're Not
Quote:
Originally Posted by Lance
Ya know, you could parallel a couple of your 830 packs together and they'd probably feed the lehner just enough to live under short bursts, and you'd make your magic 24oz weight. I pulled 22amps for a couple of seconds on an 1100mah irate pack on my "foamie that got away" last week.

Ok, gotta email Troy at BPP. Must have another lehner.

Lance
The plane was sorta built around the 2600 Tanic pack. I have some 1100 Irates I could parallel, but it's not worth the trouble. All the fretting over the 24oz was before I flew it....all worries disappeared after that. I'm all for trying to keep it as light as possible, but that thing has a LOT of wing for even a 25 oz plane. It was interesting to see how fast it would snap, yet was so lightly loaded. I wasn't expecting lightning fast snaps.

Brad, Thanks for the RPM limit link. Yeah, it would appear I'm a little over the limit, but no more WOT that it will ever see I think I'll be OK.


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