Tuesday, May 27, 2008

Part III


I’m working on the mold for the body. I have only two more braces to ‘glass to the outside of the mold and I’ll be ready to pull it off the plug. Its very exciting and scary at the same time, not knowing what awaits me under all that fiberglass. I’m of course optimistic that it’ll be perfect but since I’ve never done this before, I just don’t know.

It sounds like we may have a local Speed Run day. I bought a radar gun and brought it up at a club meeting last night and there appears to be some interest. We’ll see what sort of problems we have finding a place to pit.

The weird thing is that even as I design and build this car I’m thinking of the next one, a complete reversal of what this one is. This one is very heavy and large, the next will be sleek and lighter. I’d like it to weigh half of what this one weighs, roughly five to six pounds. It’ll be front wheel drive, only two engines in line, rear wheel steering (maybe just with a rudder on the tail). It will be very narrow and long, a drooping nose with fuel tanks up front again and two widely spaced rear wheels mounted to a CF plate or wing with wheel pants. It’ll probably be a plagiarism of Gary Gabelich’s rocket car of the 70's. I’d like to try to get it as narrow as the width of two bullet tanks which is only about three inches. The front suspension could just be a plate upon which the engines and axle are mounted and held with a spring to the lower plate. If I flipped the diff so it ran backwards it would be FWD and the exhaust would go right out the back of the engine and the intake would be out front in the fresh air. Wow, I’m liking this car more and more! Jake said that he thinks the 134 record is breakable by nitro......maybe with this it would be!

New thoughts.....Both engines lateral, tied together on a gear/ shaft (maybe a two speed?) between them with a cog pulley on the other end, the belt runs the front tire/tires.

I pulled the plug out of the mold last night......sounds easy, right? Ummmm, not so. For some reason the mold release didn’t work so well in some places, mostly where I had the most plaster and had worked and painted it most recently. I cut the bottom of the tail off but I had to do that anyway to physically get it off. Then I cut out the cockpit and removed it with great difficulty. It took about 1/2 hour to get the rest of the mold off and even though it took big chunks of plaster with it, the portions I have cleaned are very smooth. I’ve got a lot of scraping to do but underneath all that paint and plaster is a good looking mold.I may try to make a body this weekend. The cockpit has to be glassed back in and a few very minor repairs made with bondo. The thing I didn’t do was wax the plug.....didn’t think I had to....so I’ll make sure to do that before spraying on the mold release, which worked well in the areas that it didn’t rip up the plaster.

The mold weighs 2-1/2 pounds which isn’t really indicatative of what the body will weigh but it surprised me. The first body is going to be a single layer of glass/resin in the interest of reducing that weight. If It’s too thin I can make supports inside with velcro to hold it up, like I would have to do with lexan anyway. This first body will also be a test to see how the cloth lays down in anticipation of a carbon fiber version.When I layed up the mold I did it with one sheet of mat and it was very difficult. With the bodies I’m going to do the top surface first with the lower tail section removed, making it easier to work the cockpit bulge. Then I’ll tape the lower tail back on and do the two sides, overlapping the top panel slightly. I might leave working the bottom of the tail until after the rest of the body has at least set up. I’m anxious to see the end results! It’ll be wicked awesome!

I got the mold cleaned up last night. It took about an hour to remove all of the left behind paint and plaster. It was a lot of work but could have been a lot worse.....at least at the end I had a workable mold! The cockpit was glassed back in and will require only minor touch ups to be ready to mold.

I laid out the engines and drive train for Problem Child II and it looks quite workable. The entire power assembly is very compact, utilizing less than one half of the existing layout’s parts. Just like the first I’ll add two more brakes but I’m going to run both the brakes and throttle with one servo. The steering servo will steer both the rear wheels and rudder, wheels for low speed, rudder for high. It’ll also have to have ailerons to keep the car from flipping during turns...front half car, rear half plane!There is one part that is going to have to be custom made and that’s the diff spool. Rather that the standard outputs I need 1/4" shafts upon which to mount the wheel hubs. In this way I’m eliminating the A-arms, shocks, springs, dog bones....the entire suspension and outer drive train systems! My thoughts are that most of the surfaces we’ll race on are smooth enough to not need suspension. I believe this car will weigh less than half of what the first version weighed with less than half the frontal area and surface....hopefully that’ll be enough to overcome losing half the power also!While it seems that thinking of a second car before the first is done deems the first to be a failure but the knowledge and technology of the first formed the development of the second. A quick look on line and I found a solid spool into which I can epoxy 1/4 axles for the wheels I’ll be using....excellent!

Well, I tried making a partial mold this weekend using the CF material I bought. It is amazingly flexible and I have high hopes about it. I tried using my dust collector vacuum but it didn’t have enough pull. Maybe I can use Uncle Bill’s old compressor’s intake to raise the vacuum. The mold was also not smooth enough and the part came out really bad but I saw where it needed improvement. I spent the last couple days working out the bumps and cavities in the mold and am now putting several coats of paint on it and then will wax the hell out of it and try a partial again before doing a total body.
I continue to design Problem Child II....ultra light, compared to #1, and aero smooth. I’m not sure whether to put the engines upright or lay them on their sides, either way requiring some sort of roll over protection. On their sides would lower the CG considerably and they would be protected by virtue of the car’s design.....I like it already. The throttles will need a unique solution but I’m sure that can be worked out.It would be nice to be able to use a tail from an existing plane but I don’t think that would work well. Better to design from scratch and get what I want even though it’s more work. I’d like to have the tail integrated into a spine for the rest of the car to give it some rigidity. That spine could be tied into the top plate which will connect the diff, engine mount and fuel tank plate...I’m likin’ this already too! The engines have to be moved a half inch or so to the rear to clear the tires but I think this can be worked out. I’m going to start another diary just for this car.

Work continues on the mold for the body. I have it very smooth now and with several coats of paint I should be able to put a slick enough surface on it to release the body. I found a source for the breather cloth and some vacuum fittings so I should be ready to pull a body next weekend. I have the carbon fiber cloth and may try to do a CF body first cuz its so easy to work with...its just costly. The intake on my shop compressor should have enough vacuum to do the job, just need to adapt a 1/4 inch hose to it.

I have run the dyno a bit and it seems to work pretty good. I hooked up the venom speedo so now I’ll have some real rpm data to work from. Right now it appears that the highest rpm the engines are reaching is 26k, not nearly enough for 110 mph. I’ll have to find the site I found that had all the engines on it and see what they were running so I can duplicate their power.

I’m having a heck of a time with the mold....cant get the paint to lay flat. Last night I put a thick layer on and will sand most of it off tonight. I want it to be as perfect as I can get it so the final body will also be smoooooth.

I ordered two Macs pipes for testing. I know they’re good so I guess I was buying the first parts for the next car or maybe try and fit them into this one. I’m optimistic that they will have a dramatic effect and assist me in getting to full rpm.
This weekend was somewhat productive. I sanded much of the paint off and put new primer on and filled any imperfection. I then put a new coat of paint on and it came out pretty nice. I’ll give it a couple days to dry and then sand and polish it, readying it for making a body this weekend....maybe.

I also ran an engine on my dyno but was somewhat disappointed in the results. The 11 inch prop is apparently just too big as it only revved up to 11,400 rpm and got the clutch very hot. I have a smaller 9 inch prop that I’ll try and see if it’ll rev higher. Then I can see if the changes I make are reflected in the power at the top end. The site I found listed the maximum HP and torque for the Picco at around 25K....hmmm....I’m going to stick with the gearing I have and work on the engines a bit before I change too much there. Get some real data once all four are pulling at full power.It has occurred to me that the reason I’m not seeing the big numbers I want is because the engines just aren’t revving that high. I’m going to run them all in on the stand with the 9mm venturis and 30% nitro for the next test day. Gotta get the rear wing back on, too.

I was just thinking.....I could maybe revamp the body to accept the Mac’s pipes which would aid in the revving department. A simple hump on each side would probably cover them. Might be necessary to aid in getting power.

I started sanding and polishing the form last night. Its coming out very smooth and will, hopefully, produce a smooth body. It’s been a lot of work, way more than I expected. In my world I would have pulled the plug from a perfect mold the first time, but that’s not how it happened.

In other news, the 11 inch prop was removed from the test stand and a 9 inch installed. This should allow the engines to spin right up and give me better numbers on different modifications. I’ll try it tonight and get smaller ones if necessary.Good news! The Mac’s pipes that were back ordered were sent out yesterday so I should have them soon. I think they will add a lot to the HP and rev range of my engines.

Finished polishing the mold last night, came out very good. Part of me wants to try a partial body to see how its going to work, part wants to not risk having to re-do the mold if it doesn’t come out smoothly. I think I’ll try the whole thing first time. The CF easily conforms to the shape so the only unknown is the epoxy. I’ll do a ‘dry run’ with the CF and vacuum bag to try and solve any problems then rather than when I have hardening epoxy in there. (use clothes pins at the edges to keep the cloth from folding over)Very exciting!!!!!!

I changed the prop on the engine stand over to a smaller version and then a new problem showed up! The shaft between the drive gear and the prop isn’t perfectly straight and at 12K rpm it started vibrating badly so I’m going to put a mid bearing on it to keep it from bending. I’m also gearing it down to 3:1 so the shaft won’t spin so high. I’ll put the bigger prop back on to provide some drag.

The mold is ready to go! I epoxied a couple tabs at the tail to align the bottom mold and it seems to have worked. All I have to do is tape the snot out of it to hold it in place and pray it stays there during the vacuuming.

Been a while since I checked in.....last night I got the dyno balanced out and hit almost 29k rpm with a 9 inch prop so I think I’ll use that as the standard. The mid bearing on the shaft worked beautifully and it just revved its heart out with no wiggling. I also moved the throttle back behind the engine and away from rotating stuff so my digits are safe. The engine also revved freely and I’ll rotate the rest through the stand. Some fresh 25% and the 9mm venturi made it very responsive. I’m waiting for some head gaskets to bump it up to 30 and then 40%....zoom!

While reassembling the car I noticed that the drive shaft was slightly bent and that’s not the first one to do so. I don’t think they can handle the power and found a Hardcore Racing upgrade on ebay for $10. Now that I have the radar gun I’ll take the venom off and replace the input cup so it’s balanced also(no magnet or hole) At 35K rpm any imbalance is bad and it may be aggravating the situation.

I put the Macs pipes on and there was no immediate, appreciable difference in the rpm. I would have to modify the body a LOT to fit them in so I’m going to save them for the next car. Uncle Bill’s old air compressor needed a new motor so that I could get enough vacuum to form the body. I got that done but haven’t had time to check if it has enough but I’m assuming it does...if it doesn’t its all I’ve got! So it better! I have to remount the air control valve and do a little wiring clean up and it’ll be ready to test.

I would like to maybe run it this weekend but I’m not sure I can do that. I really need to run each engine on the stand before I do. I’ve got a couple evenings and Friday and Saturday to do that and remount the wing....maybe I can get it done and run. I would like to get a full length run since I’m not really sure if it’s topped out or not.

Got Uncle Bill’s compressor going last night! and it had 25 inches of vacuum!!!!! If I have time after getting the car ready to run I’m going to try and pull a body. All of the veneering stuff I ordered came in so I just need some hose and some big diameter ABS for a storage tank and I’m ret ta go!
Okay, this was a weekend for learning. After attaching all of the hoses and valves I tested the system and it held 25 inches of vacuum for quite a while. I did a dry run with the CF and again, with the bag in place, it managed to get to 25 inches and held it, not quite as well as the hose alone. I decided to give it a try on Saturday. I waxed the form a few more times and applied the pva. After mixing the epoxy and hardener I brushed a coat into the form but it beaded up. Then I laid in the CF but the edges were starting to come apart so the width ended up a little short. I put second layers along the bottom edges and at the cockpit area. I didn’t do as good a job as I should have in making sure that all of the fabric was wet. Then I put it all in a bag, hooked up the vacuum fitting and turned on the pump.It seemed to be going all right, but I didn’t have the same level of vacuum I had before and it dropped off immediately if the pump was turned off so I left it running. I was able to find a couple holes and patched them which raised the vacuum to 20 inches but it still dropped off quickly. Lesson here - always use a new bag! I ran the pump for about an hour before turning it off and setting the form in the sun.When I took it out of the bag it was quickly obvious that there were some dry spots. Also the area under the tail was incomplete. I was in a big rush at the beginning when that wasn’t necessary. I need to take more time to make sure everything is soaked. I also need to put two layers everywhere for it to be strong. Its not bad with one but its kinda flexy.

All in all, it was a positive experience. I have to decide whether to try to re-do the original form or start over and make a new one with a gel coat finish. Each has its advantages and disadvantages. I have learned enough that I think I could make a much better form now with a nice gel coat surface which would make subsequent bodies better. I have the time since the meet isn’t until October....I think I’ll make a new mold. That way I can make the cockpit better, too. For the time being I’m going to patch up the first body and use it for testing purposes.I also am going to build a dyno stand with a couple heavy steel rollers. It’ll help me tune in the entire chassis, not just the engines. More later.

I’m hoping to run the car this weekend a little bit. I have gone through all four engines on the test stand to get the tune very close to where it should be in anticipation of next Sunday’s Speed Fest. My biggest goal is just to be able to run the car and keep all four engines running consistently. The engines are finally hitting full rpm and sound great. With someone watching both ends of the street I should be able to use the entire length and get up to a respectable speed.

I fit the body to the chassis and it looks good but it’s a big, heavy car. The heads don’t stick out quite as far as I though they would and I was able to cut the openings fairly close. Some tape will help refine those openings in the final body. It will be attached to the chassis with velcro down the sides and a couple flat spots along with a few body pins. If I can get the side dams attached I may try and run it with the body this weekend but only after trying some speed runs with the roll cage in place.

I am seriously looking for 100+ at the Speed meet. The right gears are in place, the engines are tuned, I know what the gear lash is supposed to be....highly confident that it’ll happen. All the pieces are in place..... but something comes along each time. I’ll install some new tires to eliminate the split one from blowing up. The new heavy duty drive shaft is in place (still need to buy an aluminum brake mount).......I’m tired of writing, I want to run!
I had ordered some tires for high speeds and asked Jake to contact BSR for recommendations. Well, rather than foams they sent caps.....I just asked for the same tires Nic was running. Although I’m a bit ambivalent about them, it may work out in my favor if the official run is done on a drag strip since foams apparently won’t hook on VHT whereas caps will. Can’t hurt to try them.....or can it?
The buzz is that I’m expected to have the body mounted so I’ll make an effort to do so. Shouldn’t be too much work, mostly reinforcing the body in a few places and getting the air dams on. Really looking forward to Sunday. Everything is ready to go fast......where have I said that before?
Got the body mounted last night and it fits just how I expected it to. I have to put a foam spacer between the tanks and front body panel to support it and will put another layer of CF on it to make sure it doesn’t bend up and start catching air at speed. Ran new exhaust pressure lines, eliminating a few fittings, so the car is ready to run as a bare chassis. All that’s lacking now is exhaust pipe extensions and the side dams......oh, and a few stickers.
I am so tired of working on this stupid car, thinking its all ready to go and every time it falls flat on its face. Once again engines were cutting out randomly, never the same one, so there is some common mis-tune somewhere. We even tried strapping the starter pack on it so the glows were on all the time, not much difference. I don’t want to give upon this thing but it is really getting the best of me!I have to build a rolling dyno so I can tune it under load. It will require two rollers about 15 inches long and three inches in diameter with the ends cut down for one inch bearings in pillow blocks. I’ll get the electronics to go with it later . This will also be a great tuning aid at any meet since it would let me tune the whole chassis in before making a run. The electronics would tell me what setting was getting the best hp and I could always get the most out of it. Right now I’d just like to get a decent run out of it.....
The rollers are presenting a challenge....to take a piece of 2-1/2 inch steel and turn it down for the one inch bearings is about $200 plus material. Or I can take a one inch shaft and slide a couple 3/8 tubes over it and tack weld them in place. If I can find the tubing that’s what I’m going to do.
Been a while since I wrote....did some real racing last Sunday. Got a third in nitro sedan (funny...THAT engine runs just great!) and fifth in electric sedan with a strangely dying pack. Had a good time though. Brought the Problem Child along to the dismay of lots of racers. Maybe next time I’ll bring the starter box along and fire it up.While at the race I furthered my acquaintance of John W, a machinist I met at a meeting. He has offered to do the machine work on my dyno rollers so if I pick up the bearings at Grainger I might have it running this weekend then I can start tuning!
Prior to tuning though I’m going to pressurize each engine and do the soapy water test for air leaks. There is something wrong there, just can’t find it and I’m hoping this’ll answer that question.
5/14/08 - Well, well, well......the front bearings are leaking air like there’s no seal in there at all. Wrote to Picco, they were no help, just reiterating on how leak free their engines are...blah, blah, blah. Jake is going to get some Boca bearings for me and that should solve that problem.I picked up the steel on Monday and will drop it off at John’s house this evening. Hopefully I’ll be able to get the bearings soon. Jake has offered to help me tune the engines once the dyno rig is up....the more the merrier, I say!
Got a couple of the roller bearings today. They’re sealed and had a lot of drag. I popped the seals out and trimmed the inside lip so now there is very little drag. I’m looking forward to getting this thing up and rolling!5/20/08 - Not much new right now. I’m hoping that John will deliver my rollers at the meeting tonight so I can build the dyno. I managed to find a supplier for Picco parts so was able to order some head shims for the 40% and new orings and things. I also had to buy a new butane soldering iron as I dropped mine and snapped the plastic tank off. No new front bearings yet. Did manage to buy a small lot of Impulse parts for my Serpent and some more Hardcore parts for the scale TC3 I’m building on ebay....$60 for about $200 worth of parts.
On the down side, there’s no news coming out of R/C Car Action about this year’s event. It would be very disappointing if they didn’t continue what they started. There is a small group wanting to put on an event in Houston and although that would suck cuz it's so far away, it would at least be an event. Could also be disastrous.....
Still waiting on the rollers. John’s doing the machine work for next to nothing so I don’t mind waiting. I received the head shims yesterday so I can run 30-40% nitro. Jake was unable to find the front sealed bearings so I'll get them from Boca directly. Then I have to tear each engine down completely to install the new bearings and head shims. During that time I'll finish the dyno so hopefully everything will come together at the same time. We're going to try to have a speed run on June 22nd. I'd sure like to have it ready to run then.

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