Jerobee Corvette

This is the 2nd revision of proposed drive train for the RC version of my Corvette. It uses a Helicopter tail rotor motor and gear for driving the rear axle, and a small ESC that can handle up to 3 amps. I figure everything should fit under the trunk except maybe the main battery. I was thinking of using a 350 mAhr battery along with a 2.4Ghz 4 channel receiver.


proposal #2 using helicopter tail rotor motor and gear to drive rear axle.

happydad

Coming together well, HD!!! Any idea's about steering and front axle?

Way Cool Vette Lieven! That throttle linkage must have been a challenge to design. The bend-angles on the pushrod.. it's length.. the standoff/guide that transfers the motion 90 degrees to engage the throttle-clip.. Even the servo-wheel's range of motion and pushrod position had to be very precise. Great photos BTW.. good to have as a guide for maintenance/reassembly.



This throttle-clip ear looks like it had to be bent/tweaked so as not to bind.



You had mentioned pulling the engine to clean/inspect? Let us know if it has the larger .082" (2.08mm) air-intake/venturi. I'm wondering if the engine components were along the lines of Black Widow, as far as performance. Since Jerobee also made a Tee Dee version.. I'm very curious about the cylinders/porting used on both engines. Do the ground cylinders have sub-port induction? I know that "mufflers" augment the benefits of SPI.. but does an exhaust throttle? The cylinder would still be sucking in fresh air.. just less of it when the throttle closes. I just noticed the brass cylinder-shim.. maybe that's in place to eliminate SPI for use of the exhaust throttle?

Congratulations! It's a mechanical marvel.. and I hope you have a lot of fun with it! If it were mine.. I'd build a dyno for tuning it!

Thanks Roddie,

I think you are mixing up the throttle control rod and the brake rod. The rod for the throttle is straight. The rod for the brake has a strange shape and hinges on the chassis.



The Greenwood Corvette is a little different from the Comando (Mc Laren Mk8) and the Bandero (Porsche). It has the external tank, a brake and wider tyres. It was delivered standard with the heat sink and a lexan body, much lighter than the ABS one. Bolow a picture of the original box:



I took the head of and I could see only 1 transfer port. Although the Jerobee blog says that there are 2:

"Greenwood Corvette.
The Corvette was a mid range kit.
On the box it says " Not recommended for beginners".

The Corvette had a twin intake ports in the cylinder and a large external tank. Wider chromed wheels with foam tires was standard equipment.
The body was made out of Lexan, not the hard Cycolac plastic as the McLaren and the Challenger had.
This was the fastest Jerobee with Cox Babe Bee and pull start, only the Cox Tee Dee version was faster."


http://jerobee.blogspot.fr/

Lieven

OVERLORD wrote:Thanks Roddie,

I think you are mixing up the throttle control rod and the brake rod. The rod for the throttle is straight. The rod for the brake has a strange shape and hinges on the chassis.



I took the head of and I could see only 1 transfer port. Although the Jerobee blog says that there are 2:

Lieven

Yes, I see now. Still.. even straight, it's a novel way of converting to a sweeping-motion of the rod to rotate the clip/barrel. The band-brake's pushrod is baffling me. Is there a 2nd servo-horn beneath the throttle horn? I can see how it would work.. but can't see it connected anywhere. It appears that clockwise servo movement opens the throttle and releases tension on the band using the same servo.

Rodie, The hook of the brake rod is out of the hole and sits just below the servo horn. It just catches in the hole but need refixing.

This picture of another car shows the set up. Look at the small fan to cool the engine!



Lieven

As it's a calm period at work, I decided to give my Jerobee Corvette a clean. With a cotton bud and alcohol, I cleaned the chassis and all corners. I removed the engine for further cleaning. The tube to which connects the fuel pipe from the tank is the standard Cox pick up tube with the spring.





I removed the heat sink and head. The cylinder has 1 bypass port. The flyweights, clutch shaft and bell house bearing were in good condition. The hexagonal rear axle turns in plastic bearings that you have to pry open for fitting around the shaft. There is a little play on the rear axle gear. No play was found on the rear wheels. They are secured to the shaft with C clips. The brake band is a tie wrap from an electrician.







After assembling everything back together, I tested the servos. The steering servo was OK but the throttle servo was totally dead without giving any noise at all. Both servos are glued with époxy to the chassis. I tried to cut around the bottom edge of the servo with a knife to remove it without success. Not wanting to damage the chassis, I left it on there and decided to cut off the plastic servo shaft and to use the servo as a bracket for the replacement servo. This new servo is a lot smaller and fixed with a tie wrap to the original one.  This meant I had to make a new throttle shaft and extend the brake lever. Before, the brake lever was also fixed to the servo wheel. I decided to just make a hook: when the servo is turned the other way, it pulls the hook and brakes will be applied without significantly change idle.



IDLE



FULL THROTTLE



BRAKING



I just filled the tank with some fuel and will let it sit during the night to loosen residues. To be continued.

Lieven

wow nice! vettie i would love to have one of those

Regarding the "Postwoman" headline.

I always tip the local mail carriers (two ladies) at Christmas. This Christmas I used a priority mail label on the envelope and typed "To the worlds's best mail carriers" on it. I'm still getting "Thank you" cards from these ladies that deliver the mail in all kinds of weather.

These are "contract" mail carriers. In our very rural post offfice there is just one government postal employee so there is no conflict of interest in them accepting a gift.

I can't get over what a mechanical marvel this model is.. and it's luckily in the hands of a fine hobbyist!

Looks to be cleaning up good for you , that will put some pep in you step . looking good Lieven , getback

Nice jerobe! I've seen one of those years ago. BTW you know that you can get a gear set for that S3001 servo right?
Part number is FUTM3400 same gear set as the futaba S148 and the servo is still in production bope this helps! (Bandit)

Thanks guys, you're all very kind.

Thanks Bandit for the info. The reason why the servo stayed on the chassis as it was, is the fact that I can't get it off in a way that wouldn't damage the chassis. And because I can't remove the servo, I can't get to the bolts underneath to take it apart. The servo doesn't have a gear problem, I think it's an electronic failure or maybe just a loose wire on the circuit board!!

I had a look at the steering today. Not exactly Akkerman!!





To get tru rolling of the front wheels in a curve, the inner wheel should be more at an angle than the outer wheel. The pics above show the opposite. It's all in the linkages and connections to the steering arms. On original factory pictures, the steering rod is fixed between the servo and the most forward hole of the steering arm. On my model, both steering linkages are fixed to the rear hole in the steering arms. This makes a big difference. I uncoupled the ball joints at each side and put the servo in both left and right end positions. I then put each end of the steering linkages on the forward hole of the steering arm and that gives a better result:





Both ball joints will be moved forward and the I'll adjust the linkages to get a slight toe in for stable driving.

Lieven

As said above, I removed the ball joints from the steering arms to move them forward and obtain a better wheel position while steering. The left one screwed out all right, but when I was half way on the right right ball joint... oh malheur!!!!... a part of the steering arm fell off. It seems to have been broken already before just in way of the enlarged hole for the ball joint. I discovered some glue on the steering arm.



I made 2 new steering arms from a sheet of ABS to glue on the original ones for repair and to reinforce.









I stuck both steering arms on with époxy. It is still drying until tomorrow.

There was plenty of rubbish in the fuel tank so I removed the plug. The rubber gasket is "slightly dated". I'm thinking of replacing the complete tank.

Thanks Rod, yes I know; that's the original Jerobe set up with a proper track rod between both wheels. On some pictures, the track rod is connected to the forward holes and on others, to the rear ones. On my model, a previous owner mounted the servo saver and the more recent setup with 2 linkages. I just connected the linkages and did a test but it's still not the way it should be. I'll try to make a a proper track rod with only 1 linkage from the servo saver to the left steering arm.

Just throwing this out there... how about installing a linear servo and/or a small mixing tray.. if you could build one to fit? Is the steering servo glued to the chassis too?

Here's a small one..



buy it here

or this.. which fits the Futaba S3003 servo.



buy it here

Yes this servo is also glued onto the chassis. That's a nice little servo. Just as in the early days of RC but much smaller.

I made a track rod and a new linkage from the servo to the left steering arm.

Nice job Lieven! The fuel tank looks like it could be a Sullivan #435 1oz./29.5cc slant-type.



You can obtain a stopper kit #S482 which is for glow-fuel.



This might be nice too.. #S469

Save the old clunk! It looks like the tapered bullet/cone shaped clunk. You might want to reuse it as it will drain the tank a little more effectively.

All the same clunks can be cleaned and reused with no worries.

Phil

That's the tank. I'll buy a complete new one. They are sold by Scientific France. I'll save the tapered clunk.