Not your average vintage Nitro Hawk!

I posted this on RCTech, but thought it might be appreciated a little more here:

I wanted to show off my latest project, although it is not exactly new. While looking for Easter decorations in the garage a while back, I stumbled upon an old box that contained my old Nitro Hawk and Optima Mid. These had been forgotten for years, and with a renewed interest in my cars, I decided to resurrect them. The Nitro Hawk was closest to running condition, so I've been working on it the most. Its old Image .12 engine had died an ugly death early on in its life span, and I never had the money to replace it, so the rest of the car is still in pretty good condition.

Anyway, fast forward to now. I decided that it would be better off as electric, as I was intending it to be run by my kids, and I am changing my views on the "joys" of nitro powered RC stuff (all my airplanes are electric, and the next major project is an 1/8th scale electric conversion).

Traxxas has made some things easy with the basic design of the Nitro Hawk existing in the current Nitro Rustler. I decided to upgrade the tranny gears to all metal in anticipation of a brushless setup. Back in the early 90's purple was in, and so I had dyed most of the white plastics a hideous dark purple. I don't know what I was thinking. To make it look better, I completely stripped the car and dyed all the plastic parts black, and they came out looking pretty good. The only other things done to the car was to glue the tires to the rims (I hadn't done that at all when I purchased it), rebuild the shocks, and repair the body area where the rear shock tower contacts the body.

Now it was time for the hard part - the electic conversion. The Nitro Hawk's aluminum tub chassis posed an interesting problem, as there wasn't an easy place to mount the batteries with the cross brace. Also, I really didn't want to hack up the existing chassis due to the nostalgia of it, and I wanted to be able to convert back to Nitro with no trace of the electric conversion if the desire arose. So that meant I needed to use whatever existing holes were already there. This is where being an engineer and having access to a machine shop helps. Using Solidworks, I designed a motor mount that would bolt to the existing motor mount holes, and also designed a top plate with standoffs and battery tray that would sit just above the existing chassis brace and on top of the steering servo. All parts were built by me by hand in our machine shop at work. Sadly we do not have a CNC mill. I think they came out pretty good. I also had to make the steering servo mounts. For some reason, I had removed the servo years ago and lost the mounts.

Now for some specs:

All original parts except the upgraded metal gears in the tranny, the Road Hawg tires that I had purchased during its first life, and the previously mentioned servo mounts.

EZ-Run 60A Brushless ESC
HobbyCity KD36-50S-011s 3200Kv Brushless Motor
3S1P 2300mah A123 battery pack
21T 32P pinion and original 66T spur
HXT12K steering servo
Assan X8R4 micro receiver


The Nitro Hawk (now christened the E-Nitro Hawk) ran for the first time this Memorial day weekend, and I have to say its performance exceeded my expectations. This thing hauls! Its easily faster now than it ever was with the Image 12. Other than a small issue with the slipper clutch loosening after running, there were no problems at all. I ran through several packs and had a blast. My kids even drove it for a while (with ATV set to 25%). I doubt it would keep up with the new VXL Rustlers, but that was never the goal.

A week later, I broke one of the output yokes right in half. I knew those might be a problem, so I decided to upgrade to the metal versions. Much better.

Anyway sorry for the long writeup, and enjoy the pics.

-Jeff

[suicideneil]

Electro-Hawk

Nice conversion, very clean and well thought out- nice choice on the motor, though interesting choice on the batts. 9.9v nominal is a little lower than the usual 11.1 for a 3s lipo, but more than the 7.4 of a 2s lipo- nice mix of power and speed, and the extra weight of the a123s will help keep the nose down (honest, thats excuse for not having more lipos anyway ).

[Metallover]

That's a piece of art. I've never seen anything like this! Nice job!

Thanks for the compliments.

As for the batteries, I pretty much only use A123 cells in both my airplanes and cars. This was a battery pack I already had around, and so I designed everything else around it. I don't have a single lipo, but do also use standard Li-Ion 18650 cells for various things. I don't get hung up much on the voltage difference of A123 cells vs Lipos. In the airplane world, all you do is up the Kv of motor, and use a slightly bigger prop. Similar principles seem to apply with cars where weight is even less of an issue. Honestly, I think the voltage problem only really is an issue when it comes to racing, where there are specific tech requirements. At any rate, yes the mid mounted motor and forward batteries do make it difficult to wheelie, but easier to drive, (wheelies get old after a while).

-Jeff