SanJoseDale

Jamie, contact me off list

JSchoolcraft

Will do man!!

jnhiller

I ran OS VF powered Arrow's back then and recently did a redesign to electric using the E-Flite Power-52 (590Kv). I used an adjustable plug-in wing and diamond stab for adjustability and simplicity and E-retracts, which I found incompatible with a ESC-BEC requiring a receiver battery also. The removable pipe cover opens up the front half of the fuselage for equipment access.
At 4 1/2 pounds less battery the airplane really came alive with a 12-12 prop on 5S.
E-mail me for more info.
Jim

doxilia

My Feedback: (3)

Jim,

that is a very nicely engineered and built electric Arrow!

I have been working on the re-design of a similar concept electric conversion of a Tiger Tail 4 (plug-in surfaces, top access, e-tracts, etc.) but the simplicity of the top glass Arrow deck coupled with the pipe opening in the rear for cooling purposes is very clever!

Also, 4.5 lbs dry is excellent weight particularly with a painted finish (I assume it is). Do you know what kind of current draw and power you're getting from your 12x12 5s setup? Flight times on your 5 Ah batteries?

Thanks for sharing and please do post more pictures of your build and electric conversion. It might inspire me to finish mine!

David

jnhiller

Thanks Yes the Arrow was a perfect E-power subject. I use iron-on-paint (MonoKote).
The data log is posting 61A full T early in the flight with 19V (1169 W). Late if the flight I'm seeing about 55A
I can no longer fly full T all the time and I have a 4 flight average of 26A (446 W). The longest of the four flights was10 min. I don't keep charge records and don't recall ever pulling a battery below about 3.6V / cell. The Arrow and a scale airplane get used 5S pattern packs or twin 3S (6S). I should also mention that in the re-design I thinned the wing also.
I don't have very many photos of this build. but here's one of the wings before covering.
Jim

doxilia

My Feedback: (3)

Jim,

very nicely built! One can see how you saved a fair amount of weight.

Did you mount the motor on the original position firewall with standoffs or do you have a nose ring front mount setup with motor access through the top?

What kind of RPM is the Power-52 turning on the 12x12 and 5s? 6s? About 10.5K and 12.6K, respectively at full charge?

Is your wing foil down to about 14% thickness? Good penetration and speed through maneuvers now?

What kind of e-tracts are you using? Have they been reliable on the model?

I hope you don't mind the many questions - your model is quite unique among the few electric classics!

David

jnhiller

Dave,
The motor is rear mounted using the adaptor that comes with the motor. The firewall was located to accommodate the motor. Yes it installs from the rear through the top opening. This allowed a more open front for cooling air which comes in through a cut-off-nose Great Planes spinner (GMPQ 4772) which has a spoke aluminum back plate.
I haven't tacked it but the data log shows 9787 peak RPM with 5S (20.7V max)
Wing is about 13%, penetration and speed OK, but I've been spoiled flying large turnaround pattern airplanes (10S) with virtually unlimited performance.
E-Flite 25 - 46 Tri-Gear retracts have ben reliable using a separate receiver power source (2S Lipo & 10A Castle regulator. They were unreliable using the 75 A ESC-BEC, probably spiking the initial current draw beyond what is supplied, not locking in the electrical start signal on all three every time. I don't have the necessary test equipment to confirm the current surge when activated.
With 6S I probably would back off to a 12-10 prop. If I had ground clearance for a 13" prop I'd probably run one.
Here are a couple more photos. As you can see in the photo the retract quality is absolutely assume, a little pricy but I'll never setup mechanical retracts again.
Yes this is the seventh Arrow I've built, 6 glow powered in the 80's before we changed to turnaround style pattern.
Jim

doxilia

My Feedback: (3)

Jim,

that sounds like the best way to go about it. I was just wondering if there was enough space between the FW and the nose ring to insert or remove the motor from above once the FW was locked in place. It sounds like there is.

Sounds like I was about 700 rpm off and the motor is closer to about 80% efficiency on this setup.

I can understand that. I suspect that the 6s setup is a better way to go of the motor and ESC can handle it. A 12x10 turning closer to 13K should improve performance considerably. I'm actually going to set up a simulator Curare on a 60 size high Kv motor and play around with props a bit to see how the model behaves. On an OS 75AX it flies straight and level on an 11x7 (turning close to 17K) at about 130 mph and seems to have unlimited vertical. Not quite a real world situation but interesting to try things out and compare to glow performance. Power output of the 75AX is in the 2.35 bhp or 1750W ballpark.

Well, I'm glad to hear that the E-Flite units are performing well on e-power setups. A number of folks have tried to use them on glow setups in classics with no luck on the nose gear. But, with no vibration and an airframe weight of only 4.5 lbs, they should be fantastic! And it sounds like they are.

At 590 Kv, it sounds like you headed in the right direction with the motor. It might be worth sticking a power tester on it, propping down and upping the voltage to see how it fares on that. As you know, the classics were intended to be flown fast and to use momentum into verticals rather than raw thrust. With a 13" prop it will likely fly more like your 2M ships rather than an Arrow. Try getting your RPM's up and see how it fares on a lighter prop.

David

doxilia

My Feedback: (3)

Jim,

I just dropped you a PM.

David

stuntflyr

Jim,
Thanks for posting about your new Arrow. it's very nice, love the construction. I'm assembling a Curare ARF and am debating over the power system as i'm going electric with electric retracts. Great motivator you've posted there.
Chris...

immelman50

One classic that works rather well without a lot of modification is a Summit III. The reason is that it already has a suitable hatch in the form of a removable canopy. You can see it if you look closely at the side view photo.

I copied Doug's set up for his Conquest IV , although I used a Hyperion 4025-10 rather than a Scorpion. 5000mAH 6s. Mine ended up weighing 8 lbs. 7oz.with a painted fuselage and monokoted wings and stab.

I haven't flown it enough yet to be completely dialed in but a 13X9 APC seems to work well. I will try 12X11 and 12X12 when the snow melts up here on the frozen tundra .

Power and flight times are quite consistent with what I would normally fly with a good .61. If I use the same prop, my rpms are virtually identical to what a friend's OS Hanno .61 gets. Vertical is very good but not unlimited. I land at 7 minutes having used less than 4000mah. Current draw is around 64 amps.

The only thing I think I need to do is get higher C batteries. The ones I have get warmer than I like. Not excessive but I like them to stay very cool for long life. I was using Turnigy nanotech 24-50C , which are really just 25 C batteries.

Chuck

perttime

And you have good airflow into, and ESPECIALLY out of, the battery area?

Surefire

My Feedback: (1)

Jim - Your Arrow is awesome! You did a fantastic job. i assume you built it from scratch to your own design?

Beautiful plane!

jnhiller

Yes I did the redesign to insure light weight. Two things burn E-fuel, weight and speed.
The Arrow was not a large airplane that could be easily lightened and is what I competed with in the 80's.
I built only one from the MK kit the other 5 ware scratch built foam wing copies running 7 - 7 1/2 lb.
I piped the SO 61VF conservatively between 13500 - 14000 on the ground until I needed to reduce the sound level at one of the fields I was using. I added a soft mount and lengthened the OPS pipe about 2 inches and mounted a slightly modified 12-9 prop, dropping about 10 DB. The first thing I noticed was how it pulled away from the corners in a square loop with half rolls. We use to call it 'Grunt'. I also found that I used about half as much fuel and a glow plug lasted most of a season. With this behind me I was ready for turnaround with a different airplane, beginning the still evolving 'Option' series.
Jon, I'll send you the drawings.
Jim