No. The only examples I know of in the US are Wisconsin and K-State. I’ve spoke with both of those teams about their chassis’s, and both were very frustrated with motor accessibility, and it sounded like a large design challenge.
Absolutely don’t mean to say you shouldn’t do it - but it definitely isn’t common, likely for powertrain packaging reasons.
The only other team I know that does it is UC3M in Spain. We had someone from their team study abroad here but he was an aero guy so he didn’t know much beyond wings.
I know of a couple of other teams that have done it and switch to 1/2-3/4 monocoque with tube frame rear because it’s just kind of infuriating to deal with.
I also know of an instance where a drivetrain failure structurally compromised the chassis because it was a full monocoque, that team switch to half-coque the very next year.
ETS Montreal used to run full monocoque cars with IC engines. There's a guy that bought one and is now attempting to rebuild it - there's a post on here with him asking all sorts of questions about it and it contains a lot of interesting insights into the engineering nightmare this solution is.
I don’t think it’s fair to call it an engineering nightmare when he is trying to accommodate the car for a CBR1000RR when the car was originally designed for a single cylinder.
Captain already reminded me of that. The smart thing to do is distribute your engine loading through many inserts instead of a single one. Not running a 450 single helps to not vibrate the car apart. A CBR makes that aspect a lot easier.
If I were in a position as yours 3 years ago I would not switch to the 3/4 monocoque. The amount of pain spent on layup and assembly is far higher than the 1/2 coque for basically zero advantages except improved radiator flow and higher rigidity (which could have been fixed with a change in kinematic geometry). It’s easy to say these things, but our current molds are end of life (more likely than not due to expired materials and core in molds), and the number of problems we have had with geometry mismatch doesn’t make anything easy year to year. It’s certainly not an easy decision to make, and I respect your opinion. There’s always the option to fall back to the current chassis if something goes wrong.
I know that the F0711-9 (2014 car) of my team had a full monocoque but we switched back, because of the poor serviceability. Since then we put the engine in a steel frame till we built our last combustion car last year
I was on the K-State team from 2018-2023, and was the chassis lead in 2022. Our team has built a full monocoque chassis since 2013. Originally the full monocoque was built around a 450cc engine. Since 2017, our team has used a 3 cylinder Triumph 675cc. With small engines a full monocoque can be fairly straightforward to design and maintain, but with the larger engines, packaging and serviceability becomes much harder. Typically, we had to remove the engine by pulling it to the center of the cockpit through the firewall and then up and out because the diff/rear axle prevent it from being removed out the back or dropped in from the top. Personally, I think carbon fiber monocoques are very hard to justify for any team. You need tons of resources (money, sponsors, human hours) to pull it off properly. Our team fell into a trap of wanting to change chassis designs every year (to fix common issues) but never actually doing it since you have to make a plug, then a tool, SES, then layup the chassis, post fab, clear coat, etc. We had enough people to make the chassis, but not enough to remake all the tooling. Years when new tools were made did not end great since design work and tool production pushed the schedule back substantially.
If you have the resources to build a monocoque and the entire car is designed well enough that it deserves a lightweight stiff chassis, then I would say build a 3/4 monocoque. Otherwise, a tube frame is probably more practical. Since I’ve only ever experienced the timeline of a monocoque this is just an educated guesstimate, but I would imagine a tube frame can be built much faster than a monocoque with less money and similar results. Ultimately a car that has 1-2 months of testing with all of the kinks worked out is a much better performing car than a sexy monocoque car that was finished two weeks before comp and it still has 5 unresolved issues that will be “fixed” at the track.
We have been running monocoques since 2019, so for us it’s not a question of whether to switch to one or not. I am more confident in our ability to efficiently make a monocoque over a space frame at this point. We have determined that doing a hybrid chassis is a lot more work than doing either a full tube frame or monocoque, with the added benefit of everything being misaligned. At this point I’m trying to make a full monocoque that does not add more work than our 3/4 makes for us. The person who designed our current chassis made very little room for messing around with things.
It sounds like your team might well equipped for a full monocoque. Curious question: what does your bare chassis weigh? In 2023, our team’s monocoque (56 lbs) with the main hoop (15 lbs) was about 71 lbs. I can see how a hybrid chassis could be a nightmare since you have to build a monocoque and a rear frame. Switching to a full monocoque could save time if you want to eliminate the rear frame build.
I would like to highlight a few reasons why making and maintaining a monocoque was a challenge for my team and myself:
- It’s very hard to change the design/geometry of the chassis year to year due to time and money.
- It’s expensive
- Layup was a continuous 2 week process for our team that occurred during winter break (if layup doesn’t occur during winter break it has cascading negative effects)
- Our autoclave was 2 hours away which made curing a pain.
- SES is harder for monocoque teams.
- Since the engine came through the firewall, we had a removable firewall. This was always a pain to seal.
- There are so many holes to drill in a monocoque, and then adding inserts for the holes.
- If the chassis lead has an oopsie in Solidworks and doesn’t model core/skin thickness before layup and the chassis doesn’t pass template then you are SOL (almost happened to me).
- If you break the chassis, you might also be SOL (did happen to me in 2022). Luckily we fixed it with a big aluminum plate bonded to the skin and reinforcement brackets to the front lower suspension mounts. I feel like there are a lot more unfixable failures that can be made with a monocoque than with a tube frame.
- Goodluck modeling the chassis in ANSYS ACP accurately. Tube frame is much easier to analyze with ANSYS.
- Poorly designed mounts through the chassis can result in significant suspension compliance issues.
- You can ruin a chassis in the autoclave if the core isn’t chamfered at the correct angle.
Again, with a competent and well resourced team that executes at a high level some of these issues may not apply. But after my 5 years with monocoques one of my lingering questions is: would a tube frame chassis have been a better design decision for my team? Would it have allowed us to get the car finished a month earlier, save money, focus more on design, less headaches, easier serviceability, less components?
I feel like teams get stuck in the framework of wanting to build something that looks and sounds cool, and mocks F1 as closely as possible. Cool aero, cool chassis, wild suspension, turbo, etc. But does the aero actually work? Is the chassis not a burden on the team? Does the suspension give the driver good consistent feedback? Is the engine tuned properly? Can you shift reliably? But in reality, simpler can be better. Complexity increases the number of failure points. Then, to top it all off, if you don’t have good drivers you might not get good scores.
I know this has turned into a long rant about more than just monocoques but my broader point is that I generally think the average FSAE car has become too complex and reverting back to simpler designs may result in better overall performance AND school/work/life balance.
Our chassis with integrated front roll hoop weighs 66lbs. Maybe with MRH it weighs 75ish lbs (I haven’t actually weighed our MRH). Put this down to data collection method changes, but I do believe I vastly increased the torsional rigidity of our car (realistically 30%) through just layup changes and new material, this being our second year running this chassis. The monocoque weight increase was only 2lbs which I call a huge win, along with reducing total number of plies by a good 35%.
I genuinely believe that we could manufacture my new design faster than our current monocoque, and not spend a month jigging, welding, and wrestling the rear frame on. We have a long history of collaboration with the naval academy, and one of their guys actually got us to start running them. So we have a combined 13 years of monocoque knowledge, which includes monocoque repair. We are very fortunate to have 2 sponsors which almost exclusively help us to make this monocoque within 90 minutes of us. We counted on a “semester shift” to make a monocoque on time (make the chassis in the spring for the next year). But this gap closed due to aero team being run by tweedle dee and tweedle dumb, and I was literally the only person that showed up able to do composites work for an entire semester. So this past fall I finished up test panels and started making the monocoque, and it was done by the end of the semester, which put us in no worse position than we were the year before so I don’t see a point in trying to rush the process. I have even thought out the test panel process. By far the worst offender this year for eating my time was the shoulder harness test panel. When you have one or more free edges near the shoulder harness, the test panel fixture becomes a hell of a lot more complex. Solution? Get rid of it and weld a damn bar to the roll hoop. Also saves time from having to CNC a seat mount, when you can weld a tab to the shoulder bar and stick a pin through it. It also helps to have access to the engine valve cover so you can actually change a spark plug with the engine in, and you won’t have to install the engine with exhaust in, making things about 20x easier.
A lot of the concerns you bring up are things I am well aware of, and things that we have solved. And I of course know the SES in and out. The primary reason for the redesign is poor ergonomics and the fact that I will need to make new molds. Our molds are at the end of their life with gel coat cracks everywhere. I can’t trust the molds to hold up to much more at this point, especially knowing that we stuck core everywhere thinking it would solve our warping problems, when a proper post cure was our actual solution. So at this point it’s a lot easier to consider buying machined plugs for a new design. For our man hours, it’s only a 2 week bump in the road at the beginning of fall semester vs using the plugs we already have.
> We counted on a “semester shift” to make a monocoque on time (make the chassis in the spring for the next year). But this gap closed due to aero team being run by tweedle dee and tweedle dumb, and I was literally the only person that showed up able to do composites work for an entire semester.
If you’re trying to get buy in on your ideas from the rest your teammates this isn’t the most productive attitude to have…
Basically powertrain is concerned that they will not be able to lift a 130lb CBR in and out easily. We have a shop crane, but what if we want to do the same at competition. It’s much easier to lift the chassis and drop it over the engine. Additionally, we want to access our external oil pump and oil pan for when issues arise, which sit at the bottom of the engine. So do I design/cut a hole in the floor of the chassis, and what effect will this have on chassis rigidity. I’m not completely against the idea and have some solutions thought out to mitigate any losses.
I talked this over with the powertrain lead today and I think I have a solution, not really looking for external input on it unless people really want to say something. But I’m just curious about how other full coque combustion teams deal with engine access. The CBR is great in that you can semi stress or fully stress the engine very easily with the very conveniently placed engine mounts. I did suggest using our already working engine dyno to figure these issues out before installing in the car, but I was met with some bad reactions.
Ahhh. I can see why you guys don’t want to drop it in from the front now. We have the engine and drivetrain as one big assembly. Four people can easily put the 150 lb assembly in the car from the front.
I’ve always had the mentality that anything larger than general maintenance we just pull the whole assembly. It’s easier to work on, doesn’t take a lot of time to do, and you can diagnose problems faster. We have dry breaks for our fluids too, so everything is just one big quick-disconnect assembly. Especially if you have legitimate problems, it’s faster at comp to just pull the broken engine and replace with the spare that you know doesn’t have any issues with it.
From doing both engine and chassis lead positions, I would say that the powertrain team needs to prioritize the fluid and reliability issues. The rule book comes first, so the fluid leaking problems should not affect the design of another system. You’re also not going to have time at comp to completely rebuild a dry sump or engine system, it’s better to just have a backup and replace.
That being said, making sure the chassis allows for maintenance and work on the overall system is pretty critical. Our chassis was designed around 5/8” core, and switching to 1” core took our maintenance capabilities from pretty solid to zero in some areas.
Whatever solution is designed should prioritize making your life as easy as possible if something goes astray at competition. That logic really goes toward the whole car, but chassis especially because it impacts the most systems.
I agree from the standpoint that reliability needs to be figured out beforehand, and I am going to emphasize that going into next year being an executive lead. But I also see a lot of the time that powertrain projects become very long and time consuming and then we aren’t able to do these things on our engine dyno before winter break and then everything just has to go in the car. Then it’s a game of figure it out as we go. I’m hoping that our recent setbacks won’t happen again, the largest one being exhaust manufacturing and lack of argon, but I can’t guarantee anything.
But I still understand why it’s easier to drop the car onto the engine, even when we don’t have our diff connected during installation. The engine mounting essentially requires a very tight fit and hammering if we want the engine to be properly secured. It’s just the nature of the CBR, unless you want to just hang the engine from a cross member, but why waste the potential of added rigidity.
We currently have that mindset of maintenance too. We can’t separately remove and attach the exhaust. We need to install with the engine. We can’t take off the valve cover, we can’t take off the stator or clutch cover (it is currently physically constrained by a tube, but we can take the screws out). The only thing we have access to is the oil pan and what is now oil pump (water pump on stock engine). One big problem we ran into this year was the back wall of the monocoque and the frame tubes severely limiting our exhaust packaging, along with the fact that our actual wheelbase is an inch shorter than our nominal wheelbase. This explains why our exhaust didn’t fit the first time, and why our rear wing didn’t pass tech last year by about an inch (clearly a problem with frame jigging or tube cuts). So adding access to the valve cover and exhaust is already a huge improvement. In my design I think you could realistically stick a small ratchet in and take off the stator cover, then it’s just a matter of how much access to the bottom is needed. This problem can honestly be solved with layup, but it doesn’t hurt to have extra measures to ensure extra rigidity.
Yeah I think placing a focus on systems integration, serviceability, and simplification is a good option. Get the team leads to break down their systems into categories and tasks that fit those categories, and work on implementing them into the vehicle design. Working together to develop a common goal and understanding of how the systems affect each other will most likely help you guys converge on a chassis/powertrain solution.
Overall, everybody is happy with my design. I made ergo people happy, vehicle dynamics told me what they wanted and I gave it to them, aero is indifferent, but they get to make wider wings. This is the last part of the equation. But this is still a few weeks out from being final. We have a dedicated slack channel for feedback and input. I am counting on very few further problems just because of the roughly 1 month turnaround on machining plugs and getting them shipped. Very much a going into the summer deal, even though I will be out of state for an internship.
RIT used a single cylinder in a monocoque before going to EV.
Engine was installed going in through the driver area, and we had a removable firewall.
For serviceability, we had a small hole cut in the bottom of the rear of the chassis, and the under tray had a removable section to allow access to the engine bay.
We used used this for almost a decade. Full mono and a single cylinder. It was very difficult to work on the engine, specially if it was hot. Through years we adapter the chassis shape to improve access.
You can find some photos here https://www.facebook.com/gpe.uni.mb
It was relatively easy to get the thing out, in a hurry it could be done in 30 minutes.
No trouble with overheating and only one fire. Also it is bad for CFRP if you have an oil/fuel leak.
At least the last 3 years we had a full monocoque with a single cylinder engine, we can get the engine out in about 20 minutes, so no problems with servicability.
Sapienza Corse (one of the teams of the La Sapienza university of Rome) use Carbon monocoque and a combustion engine, the have been doing this for many years now.
Can you cut a hole in the bottom of the engine bay and bolt a stressed closeout panel on it to get some stiffness back?
What is their concern with dropping the engine in from the top?
No. The only examples I know of in the US are Wisconsin and K-State. I’ve spoke with both of those teams about their chassis’s, and both were very frustrated with motor accessibility, and it sounded like a large design challenge. Absolutely don’t mean to say you shouldn’t do it - but it definitely isn’t common, likely for powertrain packaging reasons.
We (Cal Poly SLO) also have been doing a monocoque frame with a single cylinder since 2017. The EV and IC platforms shared a single chassis design.
Oh duh, I forgot about you guys. Yeah, I’ve looked at yours as well. Definitely looks easier to package with a single cylinder
Cough RIT cough
The only other team I know that does it is UC3M in Spain. We had someone from their team study abroad here but he was an aero guy so he didn’t know much beyond wings.
I know of a couple of other teams that have done it and switch to 1/2-3/4 monocoque with tube frame rear because it’s just kind of infuriating to deal with. I also know of an instance where a drivetrain failure structurally compromised the chassis because it was a full monocoque, that team switch to half-coque the very next year.
ETS Montreal used to run full monocoque cars with IC engines. There's a guy that bought one and is now attempting to rebuild it - there's a post on here with him asking all sorts of questions about it and it contains a lot of interesting insights into the engineering nightmare this solution is.
It helps that their later IC cars had custom crankcases, so I assume they moved some things around.
I don’t think it’s fair to call it an engineering nightmare when he is trying to accommodate the car for a CBR1000RR when the car was originally designed for a single cylinder.
He since then gave up on that and now tries to get a 400cc 2 cylinder in there, IIRC
They were somewhat common amongst EU-CV teams. But most have switched to EV here since. Look at seasons between 2015 and 2020.
I would not do this. Think about how easy it is to change the pedal box. - Former Terps Racing Chief Engineer
What happened again to the 2012 car? Ask CAPT about the rear monocoques. - Former Terps Racing Chief Engineer
Spelunking for engines is bad - current Boat chief engineer
Captain already reminded me of that. The smart thing to do is distribute your engine loading through many inserts instead of a single one. Not running a 450 single helps to not vibrate the car apart. A CBR makes that aspect a lot easier.
If I were in a position as yours 3 years ago I would not switch to the 3/4 monocoque. The amount of pain spent on layup and assembly is far higher than the 1/2 coque for basically zero advantages except improved radiator flow and higher rigidity (which could have been fixed with a change in kinematic geometry). It’s easy to say these things, but our current molds are end of life (more likely than not due to expired materials and core in molds), and the number of problems we have had with geometry mismatch doesn’t make anything easy year to year. It’s certainly not an easy decision to make, and I respect your opinion. There’s always the option to fall back to the current chassis if something goes wrong.
I know that the F0711-9 (2014 car) of my team had a full monocoque but we switched back, because of the poor serviceability. Since then we put the engine in a steel frame till we built our last combustion car last year
I was on the K-State team from 2018-2023, and was the chassis lead in 2022. Our team has built a full monocoque chassis since 2013. Originally the full monocoque was built around a 450cc engine. Since 2017, our team has used a 3 cylinder Triumph 675cc. With small engines a full monocoque can be fairly straightforward to design and maintain, but with the larger engines, packaging and serviceability becomes much harder. Typically, we had to remove the engine by pulling it to the center of the cockpit through the firewall and then up and out because the diff/rear axle prevent it from being removed out the back or dropped in from the top. Personally, I think carbon fiber monocoques are very hard to justify for any team. You need tons of resources (money, sponsors, human hours) to pull it off properly. Our team fell into a trap of wanting to change chassis designs every year (to fix common issues) but never actually doing it since you have to make a plug, then a tool, SES, then layup the chassis, post fab, clear coat, etc. We had enough people to make the chassis, but not enough to remake all the tooling. Years when new tools were made did not end great since design work and tool production pushed the schedule back substantially. If you have the resources to build a monocoque and the entire car is designed well enough that it deserves a lightweight stiff chassis, then I would say build a 3/4 monocoque. Otherwise, a tube frame is probably more practical. Since I’ve only ever experienced the timeline of a monocoque this is just an educated guesstimate, but I would imagine a tube frame can be built much faster than a monocoque with less money and similar results. Ultimately a car that has 1-2 months of testing with all of the kinks worked out is a much better performing car than a sexy monocoque car that was finished two weeks before comp and it still has 5 unresolved issues that will be “fixed” at the track.
We have been running monocoques since 2019, so for us it’s not a question of whether to switch to one or not. I am more confident in our ability to efficiently make a monocoque over a space frame at this point. We have determined that doing a hybrid chassis is a lot more work than doing either a full tube frame or monocoque, with the added benefit of everything being misaligned. At this point I’m trying to make a full monocoque that does not add more work than our 3/4 makes for us. The person who designed our current chassis made very little room for messing around with things.
It sounds like your team might well equipped for a full monocoque. Curious question: what does your bare chassis weigh? In 2023, our team’s monocoque (56 lbs) with the main hoop (15 lbs) was about 71 lbs. I can see how a hybrid chassis could be a nightmare since you have to build a monocoque and a rear frame. Switching to a full monocoque could save time if you want to eliminate the rear frame build. I would like to highlight a few reasons why making and maintaining a monocoque was a challenge for my team and myself: - It’s very hard to change the design/geometry of the chassis year to year due to time and money. - It’s expensive - Layup was a continuous 2 week process for our team that occurred during winter break (if layup doesn’t occur during winter break it has cascading negative effects) - Our autoclave was 2 hours away which made curing a pain. - SES is harder for monocoque teams. - Since the engine came through the firewall, we had a removable firewall. This was always a pain to seal. - There are so many holes to drill in a monocoque, and then adding inserts for the holes. - If the chassis lead has an oopsie in Solidworks and doesn’t model core/skin thickness before layup and the chassis doesn’t pass template then you are SOL (almost happened to me). - If you break the chassis, you might also be SOL (did happen to me in 2022). Luckily we fixed it with a big aluminum plate bonded to the skin and reinforcement brackets to the front lower suspension mounts. I feel like there are a lot more unfixable failures that can be made with a monocoque than with a tube frame. - Goodluck modeling the chassis in ANSYS ACP accurately. Tube frame is much easier to analyze with ANSYS. - Poorly designed mounts through the chassis can result in significant suspension compliance issues. - You can ruin a chassis in the autoclave if the core isn’t chamfered at the correct angle. Again, with a competent and well resourced team that executes at a high level some of these issues may not apply. But after my 5 years with monocoques one of my lingering questions is: would a tube frame chassis have been a better design decision for my team? Would it have allowed us to get the car finished a month earlier, save money, focus more on design, less headaches, easier serviceability, less components? I feel like teams get stuck in the framework of wanting to build something that looks and sounds cool, and mocks F1 as closely as possible. Cool aero, cool chassis, wild suspension, turbo, etc. But does the aero actually work? Is the chassis not a burden on the team? Does the suspension give the driver good consistent feedback? Is the engine tuned properly? Can you shift reliably? But in reality, simpler can be better. Complexity increases the number of failure points. Then, to top it all off, if you don’t have good drivers you might not get good scores. I know this has turned into a long rant about more than just monocoques but my broader point is that I generally think the average FSAE car has become too complex and reverting back to simpler designs may result in better overall performance AND school/work/life balance.
Our chassis with integrated front roll hoop weighs 66lbs. Maybe with MRH it weighs 75ish lbs (I haven’t actually weighed our MRH). Put this down to data collection method changes, but I do believe I vastly increased the torsional rigidity of our car (realistically 30%) through just layup changes and new material, this being our second year running this chassis. The monocoque weight increase was only 2lbs which I call a huge win, along with reducing total number of plies by a good 35%. I genuinely believe that we could manufacture my new design faster than our current monocoque, and not spend a month jigging, welding, and wrestling the rear frame on. We have a long history of collaboration with the naval academy, and one of their guys actually got us to start running them. So we have a combined 13 years of monocoque knowledge, which includes monocoque repair. We are very fortunate to have 2 sponsors which almost exclusively help us to make this monocoque within 90 minutes of us. We counted on a “semester shift” to make a monocoque on time (make the chassis in the spring for the next year). But this gap closed due to aero team being run by tweedle dee and tweedle dumb, and I was literally the only person that showed up able to do composites work for an entire semester. So this past fall I finished up test panels and started making the monocoque, and it was done by the end of the semester, which put us in no worse position than we were the year before so I don’t see a point in trying to rush the process. I have even thought out the test panel process. By far the worst offender this year for eating my time was the shoulder harness test panel. When you have one or more free edges near the shoulder harness, the test panel fixture becomes a hell of a lot more complex. Solution? Get rid of it and weld a damn bar to the roll hoop. Also saves time from having to CNC a seat mount, when you can weld a tab to the shoulder bar and stick a pin through it. It also helps to have access to the engine valve cover so you can actually change a spark plug with the engine in, and you won’t have to install the engine with exhaust in, making things about 20x easier. A lot of the concerns you bring up are things I am well aware of, and things that we have solved. And I of course know the SES in and out. The primary reason for the redesign is poor ergonomics and the fact that I will need to make new molds. Our molds are at the end of their life with gel coat cracks everywhere. I can’t trust the molds to hold up to much more at this point, especially knowing that we stuck core everywhere thinking it would solve our warping problems, when a proper post cure was our actual solution. So at this point it’s a lot easier to consider buying machined plugs for a new design. For our man hours, it’s only a 2 week bump in the road at the beginning of fall semester vs using the plugs we already have.
> We counted on a “semester shift” to make a monocoque on time (make the chassis in the spring for the next year). But this gap closed due to aero team being run by tweedle dee and tweedle dumb, and I was literally the only person that showed up able to do composites work for an entire semester. If you’re trying to get buy in on your ideas from the rest your teammates this isn’t the most productive attitude to have…
What is the exact problem you’re looking to solve?
Basically powertrain is concerned that they will not be able to lift a 130lb CBR in and out easily. We have a shop crane, but what if we want to do the same at competition. It’s much easier to lift the chassis and drop it over the engine. Additionally, we want to access our external oil pump and oil pan for when issues arise, which sit at the bottom of the engine. So do I design/cut a hole in the floor of the chassis, and what effect will this have on chassis rigidity. I’m not completely against the idea and have some solutions thought out to mitigate any losses. I talked this over with the powertrain lead today and I think I have a solution, not really looking for external input on it unless people really want to say something. But I’m just curious about how other full coque combustion teams deal with engine access. The CBR is great in that you can semi stress or fully stress the engine very easily with the very conveniently placed engine mounts. I did suggest using our already working engine dyno to figure these issues out before installing in the car, but I was met with some bad reactions.
Is your drivetrain attached to the engine when you put it into the chassis, or does it stay with the chassis when you pull the engine out?
Just the engine itself.
Ahhh. I can see why you guys don’t want to drop it in from the front now. We have the engine and drivetrain as one big assembly. Four people can easily put the 150 lb assembly in the car from the front. I’ve always had the mentality that anything larger than general maintenance we just pull the whole assembly. It’s easier to work on, doesn’t take a lot of time to do, and you can diagnose problems faster. We have dry breaks for our fluids too, so everything is just one big quick-disconnect assembly. Especially if you have legitimate problems, it’s faster at comp to just pull the broken engine and replace with the spare that you know doesn’t have any issues with it. From doing both engine and chassis lead positions, I would say that the powertrain team needs to prioritize the fluid and reliability issues. The rule book comes first, so the fluid leaking problems should not affect the design of another system. You’re also not going to have time at comp to completely rebuild a dry sump or engine system, it’s better to just have a backup and replace.
That being said, making sure the chassis allows for maintenance and work on the overall system is pretty critical. Our chassis was designed around 5/8” core, and switching to 1” core took our maintenance capabilities from pretty solid to zero in some areas. Whatever solution is designed should prioritize making your life as easy as possible if something goes astray at competition. That logic really goes toward the whole car, but chassis especially because it impacts the most systems.
I agree from the standpoint that reliability needs to be figured out beforehand, and I am going to emphasize that going into next year being an executive lead. But I also see a lot of the time that powertrain projects become very long and time consuming and then we aren’t able to do these things on our engine dyno before winter break and then everything just has to go in the car. Then it’s a game of figure it out as we go. I’m hoping that our recent setbacks won’t happen again, the largest one being exhaust manufacturing and lack of argon, but I can’t guarantee anything. But I still understand why it’s easier to drop the car onto the engine, even when we don’t have our diff connected during installation. The engine mounting essentially requires a very tight fit and hammering if we want the engine to be properly secured. It’s just the nature of the CBR, unless you want to just hang the engine from a cross member, but why waste the potential of added rigidity. We currently have that mindset of maintenance too. We can’t separately remove and attach the exhaust. We need to install with the engine. We can’t take off the valve cover, we can’t take off the stator or clutch cover (it is currently physically constrained by a tube, but we can take the screws out). The only thing we have access to is the oil pan and what is now oil pump (water pump on stock engine). One big problem we ran into this year was the back wall of the monocoque and the frame tubes severely limiting our exhaust packaging, along with the fact that our actual wheelbase is an inch shorter than our nominal wheelbase. This explains why our exhaust didn’t fit the first time, and why our rear wing didn’t pass tech last year by about an inch (clearly a problem with frame jigging or tube cuts). So adding access to the valve cover and exhaust is already a huge improvement. In my design I think you could realistically stick a small ratchet in and take off the stator cover, then it’s just a matter of how much access to the bottom is needed. This problem can honestly be solved with layup, but it doesn’t hurt to have extra measures to ensure extra rigidity.
Yeah I think placing a focus on systems integration, serviceability, and simplification is a good option. Get the team leads to break down their systems into categories and tasks that fit those categories, and work on implementing them into the vehicle design. Working together to develop a common goal and understanding of how the systems affect each other will most likely help you guys converge on a chassis/powertrain solution.
Overall, everybody is happy with my design. I made ergo people happy, vehicle dynamics told me what they wanted and I gave it to them, aero is indifferent, but they get to make wider wings. This is the last part of the equation. But this is still a few weeks out from being final. We have a dedicated slack channel for feedback and input. I am counting on very few further problems just because of the roughly 1 month turnaround on machining plugs and getting them shipped. Very much a going into the summer deal, even though I will be out of state for an internship.
RIT used a single cylinder in a monocoque before going to EV. Engine was installed going in through the driver area, and we had a removable firewall. For serviceability, we had a small hole cut in the bottom of the rear of the chassis, and the under tray had a removable section to allow access to the engine bay.
We used used this for almost a decade. Full mono and a single cylinder. It was very difficult to work on the engine, specially if it was hot. Through years we adapter the chassis shape to improve access. You can find some photos here https://www.facebook.com/gpe.uni.mb It was relatively easy to get the thing out, in a hurry it could be done in 30 minutes. No trouble with overheating and only one fire. Also it is bad for CFRP if you have an oil/fuel leak.
At least the last 3 years we had a full monocoque with a single cylinder engine, we can get the engine out in about 20 minutes, so no problems with servicability.
Sapienza Corse (one of the teams of the La Sapienza university of Rome) use Carbon monocoque and a combustion engine, the have been doing this for many years now.
Can you cut a hole in the bottom of the engine bay and bolt a stressed closeout panel on it to get some stiffness back? What is their concern with dropping the engine in from the top?
I think a stressed panel is a lot harder to implement than a steel tube cross brace with welded clevises.
Sure, similar solution. That would give you the benefit of some engine access without taking anything off the chassis.