Project Ultra Hornet

[Kol__ 3535]

Looking really slick, solid and robust mate, nice work!

[ThunderDragonCy 8380]

Sneaked a little more in this morning before work. Started on the front end. This is the latest iteration of my front end block to test. It has more ground clearance and has more kick up than the original. It's now almost flush with the bottom of the tub. As a result, the socket head screw I was going to use would have stuck right out, and possibly damaged the astro at the track, so I scooped it out with a Stanley knife for a countersink screw. 

More kickup

 

All three mount holes usually take self tappers, but all are drilled out with a 3.1mm bit so I can pass longer screws all the way through and secure with nuts. 

With the linkage steering, the central mounting screw doubles as a steering link screw too. It's m3x35, and you can see it passing all the way up and screwing into the blue DB01 aluminium steering post. The carbon plate is bolted down using the scervo mount holes in the tub

Now to mount the servo. For the linkage steering, the servo gets mounted using the old MSC servo parts which are still on the parts trees. I needed to file off this edge for clearance. 

There it is all installed.

It's probably overkill, but the linkage uses two 1150 bearings pressed in on top of each other from the underside. This means I can screw them down hard without worrying about pinching them up like in bearing wheels. Super smooth. 

I also installed the body/wing mount

We will see how this looks. The high mounted rear wing is the thing I am less convinced about on the Rising Fighter, so this might get modified at some point. I also noticed the tub shock mounts on the side there line up perfectly with a rod passed through one of the shock tower holes, so I have ordered a couple of long screws to make some reinforcing rods to fit between the tower and the tub. 

 

 

 

 

[ThunderDragonCy 8380]

Couple of little bits. The 1.5mm spacers and long screws arrived, so I bolted the transmission properly to the tub

Feels pretty solid. I added these rods for the shock tower as well, but not sure how much they help. 

I think I have everything to complete the build now, but I tried to do a little more and I all was just fighting me a bit, so it's been put away until I have a proper amount of time and focus to put it together. 

[Re-Bugged 11585]

Excellent 👌🏻 

[ThunderDragonCy 8380]

Started getting the front suspension together. The original front block with lots of kick up didn't work. Once the arms are fitted they hit the new camber link mount plate very early which limits suspension travel too much. I knew this might have some issues, so I got my original design as a back up, so I fitted that. 

The DT03 turnbuckle set uses 42mm long turnbuckles on the front, but these were wildly too long! I end up using some spare 21mm turnbuckles with the adjusters almost in the middle as you can see.

The long steering turnbuckles fitted, but needed to be 5mm shorter than suggested. I need to measure the track width once the wheels are on and compare to my DT03. I may need a revised arm mounting block which has more spaced out inner pivots. 

The uprights are aluminium mainly because they were cheap at rcjaz when I was buying some other bits. The C hubs I designed (because it was cheaper to tag them onto the 3d print order than buy the DT03 parts trees) weren't quite right. I increased the size of them compared to the kit item to make sure they are strong enough in 3d printed material, but they were too bulky at the back and hit the cross member of the front arms before full extension. I cut them down easily enough with a Stanley knife.

 

I have done a revised design with a slimmer rear edge, and also a 5 deg Caster version now I am not using as much kick up. I won't order these straight away as they don't meet the minimum order by a long stretch, but if they are done I can get them next time I buy a bunch of stuff. 

Stalled again because the steel rcjaz universals I ordered are designed for the massive plastic kit DT03 outdrives. Never seen anything like it! They will need selling, and I am waiting for a proper slim set before I can get onto the finishing straight. 

[ThunderDragonCy 8380]

Built the shocks before work this morning. DT03 CVA set, but with the rods swapped out and the plastic 1 hole pistons used. Having tried the CVAs on buggies with a few different settings, I do keep coming back to 1 hole with lightish oil as the setting I like. Kit Tamiya 400 oil rear, 500 front. Used the light front springs provided and some DF03 soft springs for the rear as I generally find I need stiffer springs at the back than Tamiya usually provide. 

Built the fronts with the short eyelet 64mm, and even with my removal of material, the c hubs are limiting the droop so I can't quite fit the shocks. I have tried taking a little more off, but it's not going well. I have actually ordered the 5 deg, slimmer design C hubs because I needed to top up an order for a gearcase for @Sgt.Speirs so I think I'm going to wait for them.

At the rear, I built the shocks at the longest 94mm length with the long eyelet. With the ball on the arm in the out position, the droop at the rear seems less than the front, and the front needs a little more to fit the shocks. I need to try it out with using the inner arm mounting hole to lift the rear a bit more, but that will be once the wheels are on. The Yeah Racing 70mm shaft universals arrived, which actually fit. Kind of. I think the mounting lugs on the gearcase must be a touch narrower than the DT03, because the universals bottom out in the diff outdrives before the rear shocks fully compress. And if I need the inner position it might well compress more. As a result I've done a quick revision to the 3 deg toe in uprights making them 1.5mm wider each side so the drive shaft sits better. 

So, it's fighting me a bit now. There are always these little issues with projects though, aren't there?

[Sgt.Speirs 1416]

I completely missed that build thread here...maybe I can get some inspirations for my Grasshpper II

 

[ThunderDragonCy 8380]

Bit quiet waiting on parts, but the 3d printed bits arrived. The rear uprights worked perfectly to free up the suspension by being 1.5mm wider each side so the driveshafts have space in the outdrives. 

The front c hubs also worked, having enough clearance for full droop. Also stuck a cheeky 5 deg caster in. Lovely. 

Final thing was an improvement to the chassis brace. I increased the depth of the original part so I didn't need the spacers, and designed a new brace piece that fits over the top and adds a spreader plate for the tub

The 27t racing motor got bearings to replace the bushings. First one I have done and it was super easy. It shorted out the old tble02s I had spare pretty much straight away, so a trusty 1060 went in. I gave it a quick shakedown on street and on the 21t pinion it's pretty fast! I don't like the stance with the really high, forward set Rising Fighter rear wing. Looks tall and dumpy. Going to cut the wing mount off and look at other options to make it look a little more like the original Super Hornet. 

 

 

[ThunderDragonCy 8380]

Finally finished! I looked into wing options today and came up with something that is on the way to a solution. I removed the wing, added long CVA spacers and ball nuts to the mounting screws, then fitted these to the wing mount holes on the FRP Top Force shock tower

M3x10 screws, M3 flange nuts, and short CVA shock eyelets. The ball nuts on the wing push fit into the eyelets. The wing still rocks a little so I need to stop that, but it's in a much better place. I cut the wing mount off the body mount Rising Fighter D part and it was done. I installed off road tyres onto the orange JC Racing Products Wild One style wheels, and here we are

 

 

I put some cones out and gave it a run, and to my slight surprise it was really nice straight out of the box. No suspension tweaks needed, just a little bit of steering adjustment on the transmitter. It's so funny to me that I have battled with various relatively stock buggies to get then handling nice and these Grasshopper2 based hacks just run really nicely and seem to have quite a wide setup window. It also proved what I suspected, that a ball diff equipped DF01 transmission is a very nice basis for a 2wd buggy. 3 gear mid-motor. 

I ran it with the 21t pinion for a while and it seemed fine. It had good speed and seemed to pick up out of corners OK. These old 24 deg advance 27t racing motors are quite good! I stopped after about 10 minutes and the motor was burning hot. I had bought an 18t pinion in case I wanted to run a hotter motor at skme point, but I fitted it here, and interestingly the top speed didn't seem that different. I guess the motor must have been able to get in top of the gear more easily? I ran for another few minutes and the motor was much cooler so that good. 

Here's some shaky cam of the first few laps

I am really very pleased. I lost momentum a bit in the middle of this and wasn't sure if it had been worth the bother, but it looks great, runs well and I think does justice to name of being an Ultra Hornet. 

 

 

 

 

[KEV THE REV 2433]

On 3/1/2022 at 9:44 PM, Snappy1 said:

Someone has been watching WAY too much Tamiya Legends on You Tube lol

Superb !!

[KEV THE REV 2433]

On 3/3/2022 at 11:17 AM, ThunderDragonCy said:

Managed to drop a wet shell off the hanger though didn't I?

Haven't we all - and other parts

[KEV THE REV 2433]

On 3/9/2022 at 5:35 PM, Willy iine said:

@ThunderDragonCy  Wow!  Very cool.  

 

Man, everyone is designing custom parts and cars left and right.

Why was I born so dumb?!   ..not fair!  

 

 

 

 

 

  GL with your project!!  

Not from what I've seen with your WW's mate - outstanding work - nothing dumb there

[KEV THE REV 2433]

On 3/3/2022 at 11:17 AM, ThunderDragonCy said:

I had forgotten how quickly and beautifully automotive paint covers

I always use Auto paints - love 'em

[KEV THE REV 2433]

1 hour ago, ThunderDragonCy said:

I am really very pleased. I lost momentum a bit in the middle of this and wasn't sure if it had been worth the bother, but it looks great, runs well and I think does justice to name of being an Ultra Hornet. 

Awesome work , and it looks ultra HOT !!!!

[Kol__ 3535]

4 hours ago, ThunderDragonCy said:

It's so funny to me that I have battled with various relatively stock buggies to get then handling nice and these Grasshopper2 based hacks just run really nicely and seem to have quite a wide setup window

Mate, it's just the awesomeness of these builds that rings through to a straight forward no nonsense first run!

Totally agree with Kev, the end result is ultra HOT!

Also, please tell me that is not your insanely huge garden in that vid or I may cry with jealousy!

[Re-Bugged 11585]

Very nicely done, enjoy it 😁

[Andreas W 2510]

This turned out really well. The handling looks good and the looks - oh the looks ; what a beauty . I always did not got familiar with the integrated spoiler of the Super Hornet. To me your version looks better than the original.

[matisse 1626]

Top work bud

[ThunderDragonCy 8380]

Thanks everyone. I'm glad it's appreciated. Would anyone be interested for me to put a kit of parts on my Shapeways store? I'll put a parts list together later for anyone wishing to do something similar with a Rising Fighter, Grasshopper 2 or Super Hornet, or any of the other bodies that fit these. All the Coro Coro Dragon bodies fit, and I suspect that means an original Hornet body would too. I haven't put a budget together as that wasn't really the point, but I doubt I have much change out of the budget you would need for a TD2 Astute. Certainly much more expensive than just buying a DT02 or DT03. Not that I'm complaining. It runs really, really well and I love how it looks, and I enjoyed designing the 3D printed bits. 

@Kol__ Rest easy. This is the park 10 minutes walk from my house. It's a good place to run buggies though, especially since I bought these plastic cones to make tracks. 

[BuggyGuy 1140]

Great work, looks fantastic!

[ThunderDragonCy 8380]

OK, parts list:

Grasshopper 2/Rising Fighter tub

Grasshopper2/Rising Fighter c parts for battery door, servo posts or msc location servo mounts for linkage steering, and front body mount for GH2 or any of the Coro Coro shells.

Rising Fighter D parts if using Rising Fighter body.

Rising Fighter H parts if using Rising Fighter body

Grasshopper 2 / Rising Fighter bumper

9805307 spring mount (included in rising fighter and GH2 black edition kits)

Manta Ray B Parts trees. Thus includes the plastic motor mount and shock tower, so all the parts are on this for a light runner. I used a Top Force FRP tower for more adjustment and a metal motor mount for reliability. The Top Force EVO carbon tower would also work

50529 touring car plastic gear set. Once you have this you can either purchase the ball diff spares to build the ball diff (or just buy the Manta Ray diff set) or you can buy the bevel gears and outdrives and run a gear diff. The 50529 set has both diff case options. Note that if you start with a Rising Fighter kit, the bevel gears included fit the gear diff option for this transmission too. You just need the hard drive cups to complete.

TA01/2 5mm shaft for spur and idle gear. These are hard to find. I bought some 5mm carbon fibre tube for a couple of quid off ebay and cut to length.

DT02/03 arms front and rear

DT02/3 c hubs (b parts x 2) or my 3d printed 5 deg caster version

DT02/3 front knuckles 0550559 or aluminium equivalent.

My 3d printed 3 deg toe in rear uprights, or if you are less bothered about this, use the DT02/3 stock rear uprights that come on the b parts sprue with the x hubs

Side note – I have seen on other builds that DF03 rear arms and uprights work well and have toe in as a replacement for DT03 parts, so this would be an option here too.

50519/50520 CVA shocks built 64mm front, 94mm rear, 1 hole pistons, kit front springs, something stiffer rear, 400 oil rear, 500 front. Due to needing the short 64mm front shocks I wouldn’t recommend getting the posh df03 alloy shocks. These work great.

50591 ball collar. Two need filing down to fit front arms

10 Tamiya ball nuts

4 tamiya ball screws

TL01 suspension shaft set or screw pins for the suspension arms

3x22mm suspension shaft set for the front knuckles, or short screwpins

54396 reinforced front damper screw or equivalent screwpin

Easiest way to get turnbuckles is the full sets. If you get my linkage steering then you need the DT03 set. If you just use the stock servo position, get the DT02 set with different length steering arms for the offset servo position. If you use the stock servo position, get a long srvo saver. If you use the linkage steering get a medium kimbrough.

For the arms themselves, use the 38mm rear turnbuckle, but I needs to be as short as it can be. If you are constructing your own turnbuckles or using 3mm threaded rod, I would suggest 32mm length and maybe the Low Friction adjusters instead of the very long adjusters that come with the DT02/3 sets. And the front I used a 21mm turnbuckle to get it all to work. The supplied 42mm item is far too long.

Tamiya DT03/TT02/DF01/Top Force compatible universal drive shafts or the steel buggy driveshaft 9805551 and drive cups 2595039

6 or 7mm thick 12mm alloy hex

2 x 10mm drone standoffs (search eBay) or otherwise 10mm spacers for M3 screw for the shock top mounts

3D printed / carbon parts (required):

Carbon Front camber link mount plate from fibre lyte

Transmission lower bulkhead

Transmission upper bulkhead/tub mount

Transmission upper bulkhead spreader plate

Transmission side mount left

Transmission side mount right

Transmission base plate (from fibre lyte)

Top Force J5 or my 3d printed repro version

2 x m3x60 screws

3 x M3 x 25 screws

5 x M3 flange nuts

4 x M3 x 10 cap head screws

2 x M3 x 8 countersink screws

4x M3 x 12 countersink screws

2 x M3 x 10 countersink screws

Front suspension arm boss

3D printed parts (optional):

DT03 3 deg toe in rear uprights

DT03 5 deg Caster front c hubs

Grasshopper 2 linkage steering link (you need the DB01 alloy steering post 54148 and my carbon base plate from fibre light, plus extra adjusters, long piece of M3 threaded rod, 2 x 1150 bearings, m3x35 countersink screw, m3x8 button head screw, 2 x m3 x 20 cap head screws)

Any tamiya bearing front, 12mm hex rear 2wd wheels. Tyres for whatever surface you run.

Assorted screws for putting everything together. Mostly M3x10 with a few M3 x 25 and others thrown in. 

11 x 1150 bearings

3 x 850 bearings

[ThunderDragonCy 8380]

Final touch - driver figure. My painting skills are sorely lacking so this is super basic, but I had to do it. 

And here is Ultra Hornet with Grasshopper 2 Ultra G. Unfortunately the tble02s in Ultra G spat its dummy so I didn't run it, but Ultra Hornet went well. 

 

One thing having them together did finally make me decide is that I don't like the JC Racing Astute style wheels on Ultra G. They are too fussy. I think I will get some of the Wild One style like Ultra Hornet, but go back to Fluoro yellow for my Super G style. 

 

 

 

[ThunderDragonCy 8380]

Another run out on the short grass around the football goal at the local park. This time with a fully functional Ultra G to compare it to. I ran Ultra Hornet first, and on the dry grass the front end was almost too sharp. Turn in off throttle was very quick, and I grip rolled once. The front is good on both Ultra G and Ultra Hornet, but the brushed motor used here seems to give more braking off throttle. I decided to try se slightly stiffer front springs. I was running the really soft springs that come with the 50519 CVA shocks. I went to the TRF201 brown soft springs, which are only a little bit stiffer. Was really nice. Just took the edge off that snatchy off throttle feel, but still kept some grip on throttle cornering. 

Was interesting to compare to Ultra G. The Top Force rear end with ball diff is much calmer over bumps, and has better traction because of that diff and being a bit stiffer in roll than Ultra G. It's not that Ultra G is bad, but it is noticeable. Keen to compare once I can get back to the AstroTurf track. On that surface, Ultra G never struggled for traction due to the grip. 

I checked the ball diff and its still smooth and tight, which is brilliant because it don't have a great history of keeping ball diffs unmelted in buggies. I will give it a strip and check after a few more runs. I bought some 3mm ceramic balls for my TA04, but it actually needed smaller balls so I gave them spare now. I'll put them in this diff when I next pull it apart. 

[ThunderDragonCy 8380]

First time at the club for months. I am racing my FF01, but thought I would bring Ultra Hornet for a few laps of the offroad track before it all starts. Nice to give it a run. Worked quite nicely

[ThunderDragonCy 8380]

First Junkies meet since March today so finally got to run this on the track. Indoor flat astro and outdoor big (damp) astro

It was easy enough to handle on the dry astro as I brought it, but on the wet outside it had no rear grip. Was quite surprised as Ultra G ran OK and I figured the ball diff would help. Black read wheels show a change of tyres from mini spike to mini dart which did help, but it was definitely lacking rear grip compared to Ultra G. 

I took the preload clips out and that helped, and then put much softer rear springs on andthat helped again, but definitely not quite there. Was much easier to drive inside in the dry (the video), but I think it still needs some tweaking. I suspect some lighter damper oil might help. I was also having to run the shorty battery right at the front to access the plugs, so I think drilling some holes in the battery box so I can mount it fully rearward will weight the back end a bit better. Some new tyres too. Ultra G was running Schumacher Mezzo and they were great. I'll get some more. 

One thing from running this and Ultra G (with 13.5 brushless and decent gearing) back to back is that this is quite a bit slower. I really like the old school brushed motor, but I think something a little spicier is in order. 

So, a solid first outing. Hopefully we will get plenty more track running next year.