Getting Aero - Speed Gains

Discussion in 'Motorized Bicycle General Discussion' started by lowracer, Mar 11, 2012.

  1. BarelyAWake

    BarelyAWake New Member

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  2. lowracer

    lowracer New Member

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    BarelyAWake,
    Thanks for adding those links.
    Good stuff...
    -Lowracer-
     
  3. BarelyAWake

    BarelyAWake New Member

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    NP Low, there's a bunch of fascinating info out there - those were jus' a coupla links I had handy...

    It's interesting to note that with cars & (motorized) bikes aerodynamics are often effectively ignored when making preformance modifications for speed, it's always about a bigger/stronger engine, yet with aircraft - engine power is for climb rate & it's pitch is for speed... and the best way to improve the aircraft's top speed preformance is through a reduction in drag, even such seemingly inconsequentials as wheel pants (covers), airfoil shaped cables & struts and even just taping over the seams, I was simply astounded by the results I got from such "minor" modifications to my ol' ultralight, even small & slow as it was (stock airspeed 60mph).

    Still, lessons learned & I've been giving serious thought to adapting some of the various velomobile designs to the taddy project I've been tinkerin' on, but you have touched on some of my concerns;

    ...while a tadpole would be more stable in a crosswind, the biggest hurdle for me is ofc your 2nd point, with the distinct lack of shoulders on most of the roads around here I almost didn't go through w/building a taddy at all - there's also the difficulties of lessened road visibility & difficulty in entering & exiting the thing... then there's cost, even just a simple one piece fairing can run around $230, it's mounts another $270, so it's roughly $500 for a windscreen alone... and TBH I'm having a hard time justifying that ATM lol (as I'm still building the silly thing).

    Still, the advantages in efficiency & comfort can't be denied, sooner or later I'll get something like that fairing, or get creative & build somethin' myself... although I'm not expecting much, while it's ofc exponential the drag considerations for a 30mph or less motorized vehicle are comparatively fractional, but it does all add up I s'pose.

    The enemy lol: [​IMG] ...& gawd don't I hate math >.< :p

    Thanks for mentioning this Zzipper BTW, it's good to have some choices & I'll defo be keepin' an eye on yer DIY progress (^)
     
  4. lowracer

    lowracer New Member

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    I know its an old thread, but my wife found some great old photos of stuff I put together yesteryear & rode them silly...& I wanted to share these.
    If only I would have thought of motorized assist back when I had these trikes...
    I think a motorized aero-trike would make an excellent velomobile for all conditions except maybe narrow shoulderless roads with lots of car traffic.
    I don't think gaining an aero advantage would be considered old news anyhow...
    Cheers,
    -Lowracer-
     

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  5. lowracer

    lowracer New Member

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    A few more pics & why I began using the nickname 'Lowracer'.
     

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    #25 lowracer, Apr 20, 2014
    Last edited: Apr 21, 2014
  6. Dan

    Dan Staff
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    Such a cool thread. Really enjoy when they come back. TY, Lowracer. And Mrs LowRacer.

    Years back did some movie work making giant aquariums and some odds and ends. Kind of amazing. Take a sheet of plastic. Make a mold with "wiggle wood" and just heat it up. Joints with glue were like welds. LOL, I know this from having dropped a finished product a few hrs after it was needed badly. (bad, bad day) It broke every which way except for where it had been glued.

    But am thinking aside from speed gains, a DIY faring would be pretty awesome. Rain and cold for instance. Not a really hard DIY?

    Har, "drafting" behind large vehicles?
    Bad idea. Funny, but really bad.
    ("Wut happened to your face?" "Truck stopped at a light")

    Even some thing like the bulbous bow, I would think would be of great advantage in breaking the wind around you. https://en.wikipedia.org/wiki/Bulbous_bow

    Again, great idea LowRacer. With such little power, would be a heck of a boon.
     
    #26 Dan, Apr 20, 2014
    Last edited: Apr 20, 2014
  7. 16v4nrbrgr

    16v4nrbrgr New Member

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    The fairings really do help to get more top end speed, I have used various fairings on my moroized bikes to help cut down on high speed drag too. They especially help when you crouch with a full face helmet into the front fairing and your helmet becomes an extension of the fairing and your back becomes teardrop shaped to the bike. Thanks for sharing your awesome recumbents Lowracer, I bet they all went very fast and slipped through the air with minimal effort. I especially like this trike you made, bet it was a blast!
    [​IMG]
    Here are the bikes I've done with windscreens which are noticeably effective in a crouch according to the speedometer.
    The Cag powered moped
    [​IMG]
    The eMotard
    [​IMG]
    and the KTM Chopper
    [​IMG]
    A simple windscreen is pretty easy to make from polycarbonate and a heat gun, or various front fairings can be bought online for cheap, they're well worth it if you're looking to smooth out the cruising experience because they make a bubble of calm air behind them, and work great for top speed if you crouch behind them.
     
  8. lowracer

    lowracer New Member

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    Dan & 16V,
    Thanks for posting.
    The 1st fairing around the Greenspeed trike was a way better setup than the one around the Windcheetah trike. It was more solid & I believe more aero.
    The yellow bike Lightning F40 was the fadtest but most dangerous. Being fully faired (except my head) on a 2 wheeler was both fast and scary. In crosswinds & with passing trucks, I had to be extra conscious of the wind that was going to be changing my line. I wouldn't motorized a two wheeled fully faired vehicle.
    The 1st trike was awesome. It didnt get me going as fast as the two wheeler (which allowed a hi powered cruising speed of 40 mph) and weighed a bunch more, but definitely stable and great for cold weather (I still don't ride in the rain).
    An axle mount kit would have been perfect for that trike since it would still keep the engine noise and fumes out of the fairing and away from my head.
    I think it would also benefit from a longer wheelbase especially since motorized would yield faster cruising speeds. Something like Cannonball2 suggested & I added to '2High' the tall bike to extend the wheelbase would be about perfect.
    -Low-
     
  9. BarelyAWake

    BarelyAWake New Member

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    [​IMG]

    It's the "HP required" percentile difference that's simply stunning and as that's only at 20mph, remembering wind resistance is exponential (double the speed, wind resistance increases four times etc.).

    Touring 100% @ 20mph
    Recumbent 75% @ 20mph
    Equals a 25% reduction in power required to maintain 20mph... & that's even unfaired, just rider position.

    There's precious few engine mods that'll boast such massive differences ;)
     
    #29 BarelyAWake, Apr 21, 2014
    Last edited: Apr 21, 2014
  10. lowracer

    lowracer New Member

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    BarelyAWake,
    Good stuff you posted.
    I remember reading info like that with the early days of Recumbent Cyclist News (RCN by Bob Bryant), the IHPVA info online as well as WISIL's website.
    Back then, I competed on a Barcroft Oregon Lowracer at a few of the HPV races & learned alot about the different rigs the racers were riding in the different classes. Everyone was very friendly & willing to share their know-how.
    Incorporating faired HPV technology with Motorized bicycling seems like the natural progression towards a more fuel efficient, aero, lightweight, all weather hybrid vehicle... Velomobile?
    -Low-
     
  11. BarelyAWake

    BarelyAWake New Member

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    I decided to make the transition from upright to recumbent primarily for comfort & experimenting with fuel efficiency, I'm beginning my second season with it now and yet I'm still undecided if I'll pursue aeromods, be it just a fairing or a full velo shell...

    [​IMG] [​IMG]

    ...it is a "natural progression" as you say, the advantages both undeniable & profound but there are additional considerations that continue to give me pause, some of which I've mentioned previously (expense, maneuverability, ergonomics) and as the 'T3' experiment has already succeeded in it's original goals, last season spent in testing - I'll prolly not do much other'n just play with it this season, aside from whatever refinements may crop up.

    This is one of the primary reasons I've been hesitant to velo, admittedly it's got very little to do with practical application or fabrication & just the limitations of my shop space, I came very close to building a "ship in a bottle" lol, another inch in any dimension and it'd not fit out the door - so any aeromods would have the additional complexity of having to be quickly & easily removable, even with a full velo shell I'd not want to be forced to store it outside;

    [​IMG]

    Still, the temptation is there - not just for the almost irresistible preformance advantages & all-weather comfort, but for the opportunity to tinker as well. While I've not committed to building a velo shell, I've not stopped hunting around for different build techniques, materials, shapes & styles & so far while not the most aero, I've been tempted by something like this example below as it's simple, all flats construction would ease both budget & build;

    [​IMG] [​IMG]

    ...and would at long last provide a place to mount a blasted cup holder, which may have a disproportionately predominant priority on my "to do" list lol
     
    #31 BarelyAWake, Apr 22, 2014
    Last edited: Apr 22, 2014
  12. massdrive

    massdrive New Member

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    The bikes are really cool looking and I am very familiar with the benefits of aerodynamics. Although there is a lot to be said for feeling the wind rushing over me, and I do like to see the mechanics of any machine.
     
  13. The_Aleman

    The_Aleman New Member

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    Duck n pedal harder
    If ya have the need for speed
    Horsepower is the easy way there
    If you have the need for greed.

    IMHO, the faster you go on these, the dumber you are.
    You know who you be.
     
  14. lowracer

    lowracer New Member

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    BarelyAwake,
    True, by adding more material and size decreases mobility.
    For me when I did this experimentation 16 yrs ago it as more about seeing how far I could push the envelope of human power by getting as efficient thru the wind as possible with a budget. I started with just a front fairing, then a tailbox, then wheel covers, then the whole shebang (except the radiator....my head). The front fairing did a little, but not much. The rear tailbox, maybe a little but less than the front fairing, The wheel discs, again maybe a little, but not much, but the whole shebang did about 40% (at higher speeds).
    Going from faired to unfaired after experiencing the faired advantage was hard to do. I ended up selling all my aero bikes & trikes but kinda wish I didn't. Who knows, maybe one day I'll revive the lust and build up another trike using coroplast and a bubble and motorize it to for fun.
    This thread is about discussing 'Getting Aero-Speed Gains'...not really the '20 mph Club'.
    -Lowracer-
     
  15. The_Aleman

    The_Aleman New Member

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    I never said I was promoting the "20 MPH Club". You assumed I was. How many times have you gone over 40MPH on a pedal bicycle?

    Just curious. I used to do it twice a week or more from 1988-1995. I know a little about aero on a bicycle. I've gone over 60 on a pedal bicycle.

    But still, it's my opinion that going fast on a bicycle is dumb. Especially with engines. I've done 50+ without them many times.
     
  16. BarelyAWake

    BarelyAWake New Member

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    Speed and efficiency are related, but not the same. Reducing load in any fashion can result in a faster build - or one that requires less to achieve similar results.

    "Speed" is also relative - if someone had a motorized bike with a 30cc helper, they may be interested in areomods to go "faster" and that faster would very likely be on par with a 49cc build, without areomods.

    You've quoted "pedaling harder is the cheapest speed upgrade" and while I agree to an extent, it too presumes speed is the outcome... but it's only one application, not the only application. To carry the example areomods to a chassis can be seen like pedal assisting to a motor, should you choose less work or go faster, it's your choice.

    I wouldn't have chosen a 49cc four stroke hybrid if my interests were pure speed, I could have halved the weight with three times the horsepower had I chosen a two stroke... a clear illustration that efficiency & speed aren't the same. I chose a four stroke for it's fuel consumption rate and torque, my build a comfy cruiser heavy hauler, trailer in tow. If I choose to aeromod, it'd be with the same goals as the entire build had - comfort and efficiency.
     
    #36 BarelyAWake, Apr 22, 2014
    Last edited: Apr 22, 2014
  17. The_Aleman

    The_Aleman New Member

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    Of course it's relative, and aero plays a huge part with low-power engines. But at legal speeds (<30), aero doesn't play as much a part as it does at above legal speeds (>30). You likely know this. The faster you go, the more aerodynamics matter. At the speed MaBs are legally limited to, with the fact we have a gas or electric motor attached, makes the point of having fairings and/or lycra/spandex rather moot for everyday riding.

    Understand this: it's open to many interpretations. Regardless of semantics, "speed" can be understood as acceleration, top speed, or cruise rate. I made that quote over a year ago when it seemed to me many people were putting increasingly powerful engines on their bikes while making pedals more of a "backup" thing to use only when starting their engine, running out of gas, or increasingly, just to be "legally" compliant on what is actually the illegal motorcycle they have built. People spending money on the "assist" part of their bicycle and making it the primary propulsion while neglecting what is truly the primary propulsion unit of a bicycle: chevrolegs. Not pedaling on a bicycle is completely silly to me - engine or not. Regardless of what I think tho, pedaling a bicycle produces more torque than many drivetrains people are bolting to their bicycles, yet they do so so they don't have to pedal anymore. I don't know about you but I see a lot of irony in that. When people are spending money to go faster on their motor-assisted bicycle, pedaling harder is still the cheapest speed upgrade. This is not my opinion, this is a fact. Most of us have no problem eating, but many here have issues with pedaling their bicycle.

    Again, this is your interpretation of my somewhat tongue-in-cheek signature statement. And I disagree with you about aeromods: they are _nothing_ like pedal assisting a motor. Not at all. Pedaling is adding power, aerodynamics reduce drag. Aerodynamics do not increase power. The end result may be similar in that both have increased speed and fuel efficiency, but at legal motor-assisted bicycle speeds, aerodynamics play a very small part in overall speed and efficiency compared to simply pedaling or adding more power. Sure a headwind will skew that in favor of being slippery in the wind, but again, pedal torque costs nothing but the rider's own energy. We all likely know the faster you go the more aero matters, but legally we are limited to speeds that aero does not matter so much.

    I can show you many instances where increased speed directly results in increased efficiency, but they all involve processors or certain jet engines. Apples and oranges here of course, but let us focus on your statement where you say you chose a 4-stroke: fuel consumption rate and torque. If you have geared your tadpole to have usable pedal gears at any reasonable cruising speed, you will reduce fuel consumption rate and increase torque by simply pedaling. Not only that, but you can also increase acceleration and top speed when you simply pedal. Potentially moreso than a standard bicycle even, because your tadpole has a seating configuration that results in higher average pedal torque when seated than a standard upright bicyclist can attain. Maybe less peak, as you can't stand on your pedals, but definitely higher average.

    Now that you've given your ride's example, I'll give mine: my ride is set up so that peak pedal torque is at the same RPM as peak engine torque - in each gear. Peak pedal "horsepower" is at the same RPM as peak engine horsepower. My bike with me on it is neither light (305lbs with a full fuel tank) nor particularly aerodynamic (I'm 6'4" 225, wear jeans and sit upright), but it's capable of 0-30MPH in under 5 seconds when I pedal. It can cruise all day long at it's maximum legal speed. Without pedaling, it would be a lot slower in acceleration, although top speed wouldn't differ much (36MPH). Granted, if I had aerodynamic modifications I'd likely be able to increase my top speed and cruise speed against a headwind, but I rarely go over 30MPH anyway.

    I'm not against aerodynamics or anything, I know first-hand they play a _huge_ part on bicycles. If anything, one will notice quickly any difference he/she makes in decreasing drag when it comes to bicycles. The first headwind you fight will make you a believer let alone speeds above 40MPH. It's just that if you have an assist engine on your bicycle, have pedalable gears, and aren't interested in exceeding the speed limit, then aerodynamic mods aren't really that important. Pedaling is still cheaper!
     
  18. BarelyAWake

    BarelyAWake New Member

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    I had just posted this, I just can't agree a "25% reduction in power required to maintain 20mph" is moot;


    Be it a result of pedaling, aeromods or gearing tweaks - faster is faster & I'm failing to understand why areomods in particular have drawn your ire. Builds utilizing engines grossly in excess of legal parameters can be a hazard to our activity and in many ways I share your concerns, despite stickers & claims otherwise, overly large displacement engines are an obvious violation of size and/or power restrictions (state dependent). Yet, there is no region I'm aware of that prohibits aeromods, or pedaling for that matter. What states have a speed restriction it's up to the operator to obey, the occasional "not capable in excess of" a bureaucratic impossibility.
    "The end result may be similar in that both have increased speed and fuel efficiency..." - is the bit I meant.

    "...but at legal motor-assisted bicycle speeds, aerodynamics play a very small part in overall speed and efficiency" - is the bit I disagree with, as previously exampled.

    You've presumed I haven't availed myself of my build's pedal gearing to assist, odd given I've spent so much effort extolling the virtues of efficiency, torque & reduction of fuel consumption - or even that we're running the exact same engine type & displacement. I'll spare you the details of my build's specifics save to say, I've 21 gears available to both the engine and my pedal drive so yes, I do have a range appropriate for my needs.

    This is where the misunderstanding stems I suspect, you've presumed the thread title 'Getting Aero - Speed Gains' to be referencing "speed" you don't approve of, most likely in excess of your stated "36MPH" top speed... yet this is a presumption based on "aerodynamic mods aren't really that important" below that speed, which if you'll forgive me is flawed in both presumptions.

    Importance and speed both are comparative, relative terms, even 20mph "fast" to pedalists, I consider 25% a considerable percentage, important enough to me to choose a recumbent over another upright anyway.

    Point being, you've jumped into a thread casting aspersions based on presumptions with only a vague "You know who you be" in lieu of any credible context... highly unfortunate as you and I share similar interests & build dynamics, lowracer & I happily sharing primarily HPV aero data, lowracer offering numerous examples of his pedal-only recumbents & velomobiles. I would have thought you would have accepted, if not embraced this legal method of increasing efficiency, reducing the HP required for even legal speeds, or whatever speed you think appropriate - even contributed as you say, you've done this before. Interestingly, aside from a mention of human powered records you're the only one that's made any top speed claims to date in this thread.

    I fear you're mistaking advocates for enemies, even when they could be allies - I would strongly suggest reevaluating the context of your complaints and finding a more suitable venue, of which I'm sure you're keenly aware of in both propensity & popularity, even in this forum if not this thread. I personally would like very much to cease quibbling over semantics and resume the sharing the technological details of aerodynamics & construction techniques, the results of which like any other - up to the operator to utilize in whatever fashion they deem fit.
     
  19. lowracer

    lowracer New Member

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    BarerlyAWake,
    I agree with you.
    I don't go around looking for thread topics that I'm not interested in, jump on in to spew my negative opinions for effect.
    If I don't have anything good to say, I don't say anything at all.
    In my experiences some of the time & money I've wasted learning the wrong way to build or about a poor product I will try to post in related threads to possibly save a new member the same aggravation I went thru.
    The thread 'Getting Aero-Speed Gains' was meant to blend the bicycle-tricycle HPV community with those interested in EcoModding using the motorbicycle to gain efficiency. I've been fortunate enough to stumble upon both the human powered side of things with fairing recumbents to improve efficiency & motorbicycling, just not both at the same time in history.
    I draw inspiration from the Shell Eco Marathon races held each year and the vehicles people produce that yield super-high fuel economy numbers using very small gas engines, super low drag coefficient lightweight bodies, and a bit of ingenuity. Lets face it, gasoline isn't going to be around forever, but probably longer than anyone reading this. Many get into our hobby because they think it would be cool not to have to pedal anymore, some because they lost their ability to license & register a motor vehicle, some cause their spouses won't let them buy real motorcycles, etc..., there could be a vehicle created on this forum capable of most of the necessary attributes for daily commuting to replace the car?
    1- weather protection (rain, cold, sun, snow) accomplished by fairings
    2- visibilty/safety/stability (again fairings & trike platforms)
    3- fuel efficient / aero efficient (fairings)
    4- easy of entry & exit + clothes staying clean (raised seating position trike, wheel & under body fairings)
    5- exercise (pedal assist)
    6- low noise (well muffled, or electric)
    7- etc...
    BarelyAWake, I'm still leaning towards a tadpole trike like you have (stability), with a few fairing mods to add weather protection, keep the clothes dry/clean & of course fuel/aero efficiency, as well as the visibilty factor (You're gonna see a huge colorful aero shaped teardrop rolling down the road!)...I think front & rear suspension would also be a huge benefit for the everyday commuter vehicle. The Shell Eco Marathon vehicles are all about lightweight & don't incorporate suspension or cabin comfort to try & win their respective prizes.
    -Low-
     

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    #39 lowracer, Apr 23, 2014
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  20. BarelyAWake

    BarelyAWake New Member

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    I also look to the students participating in the Eco Marathon races for inspiration, their fresh perspective offering unique ideas & advancements - while I'd go a different route in construction materials, the hydrogen powered vehicle below offers quite an interesting body design, one although not the most areo - looks to be quite comfortable & simple to build and is another style on my "considering" list lol;

    http://www.aston.ac.uk/about/news/releases/2012/may/-design-award/

    [​IMG]

    [​IMG] [​IMG] [​IMG]

    Even aside from the better control a suspended vehicle offers on rough surfaces I'm of the opinion suspension is a near-must with motorized recumbents in particular, as it's not possible to absorb sudden jolts with your knees like when riding an upright. Without this ability a hard enough bump can cause you to leave the seat, even if momentarily this can cause control issues or at the least, be somewhat unnerving & uncomfortable.

    Having said that, I've not had any serious cause for concern with mine, suspended as it is. I would suggest shocks with some sort of bound/rebound control/dampening as the typical, basic coil-overs offered on some recumbents could result in more bounce then without shocks at all, particularly with the added weight of motorization. It confounds me that many of the oh-so-pricy factory recumbents often come with such low-end, basic shocks, they're often oversprung as well as although a trike does weigh a bit more then a bike, it has three shocks instead of one or two... I'm actually "oversprung" (much to my surprise) with my RockShox Monarchs, but as they're air it's not an issue... anymore lol

    As you're considering a suspended tadpole, I thought I'd pass along this lil gem - when I was first considering building a tadpole trike fully suspended ones were very rare, leaners more rare still & not perfected. In the time I spent during R&D I decided to forgo the leaner aspect as there were still high speed stability issues and no relevant fully-suspended leaners existed to use as examples - I had my hands full with other design challenges in any case.

    There's been a number of advances meantime, fully suspended taddys are now almost commonplace & Steintrikes for one has stepped up to the challenge of a fully suspended leaner - while perhaps difficult to redesign to a motorized chassis and more difficult still to velo, this is quite an interesting platform to consider... if this was a couple few years ago or I wasn't as pleased with the 'T3' as I am, I'd be seriously contemplating this for a project;

    vid, leaner in action: http://youtu.be/wpYIIpYJHwY

    http://www.steintrikes.com/index.php

    [​IMG]
     

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