Aprilia SR 50 Ditech powered BlueSkyDesign Aerocoupe tadpole commuter

Discussion in 'Off Topic' started by DetonatorTuning, Jun 15, 2011.

  1. DetonatorTuning

    DetonatorTuning Active Member

    by srdavo's invitation,

    some of you know me, others will need some background and that can be had by using the " advance search " to look for "threads started by "

    my previous builds threads were, in chronological order:

    TREK 4500 / GEBE w/ GP460 build
    TREK 4500 / GP460 now Staton 18.75 Drive
    TREK 4500 / GP460 / 8 speed SHIFTER
    TREK 4500 / GP460 now twin belt jackshaft

    my interest in MB's was the result of a desire to develope a totally dependable all weather ride consisting of light motorcycle grade ( read DOT approved ) parts. esp. wheels, brakes, tires.

    while looking at velomobiles i found the " Quest" tadpole and from there found this site by that bikes creator.

    http://www.velomobiel.nl/allert/Recumbent motorbike.htm

    this gave me lots of ideas, but i soon found that there are NO engines and no parts to complete a fuel injected air cooled honda or clone engine in the States. so, i was back on the prowl.

    still hunting in velomobile circles i happened upon BlueSkyDesign and more specifically :


    now the search was on for a driveline, in the mean time i had begun doing tuning and repair of 2T scooters, getting to know and like the unititized engine / cvt / swingarm configuration of them.

    there are of course "levels" of quality in these scooters. the real junk chinese stuff going from $500. - $800. then the better grade japanese, korean knock off market in the $1000.- $2000 range, some of which are actually quite good. and finally the Honda, Yamaha, Suzuki, and European topshelf offerings from there on up.

    after a yr. of working, reading and waiting the donor bike i wanted, for reasons that will become appearant, showed up on craigslist 20mls. away. that being a 2003 Aprilia SR 50 Ditech.


    the 2003 didn't have digidash, and has the Morini instead of Piaggio engine.

    these scoots do 50mph and get 112mpg in stock form. the one i got has a 70cc BBK kit with all the goodies, has enough acceleration to run away from cars at stops and lights, goes 60mph and gets 90mpg on the stock 13" rear tire. i have a 16" wheel and tire from an Aprilia Scarabeo Ditech that is going to drop my topend rpms and increase both my top speed and MPG's, although not all at the same time.

    i'll be adding pics and build progress as i can.


  2. srdavo

    srdavo Active Member

    Thanks Steve. Looking forward to seeing your new ride.
  3. nwohater

    nwohater New Member

    Wow you did do your homework on this didn't you? I really would like to see pics of that engine and get info on size and weight once you pull it. Sounds great...

    And love the velo shell style, I think I'll copy it in coroplast. :)
  4. DetonatorTuning

    DetonatorTuning Active Member

    it's been 2 yrs. of just hard copy and digital investigation till the first of this month when i picked up the aprilia sr 50.

    i'll be loading up pics and stats this week end. i can get a weight estimate for the driveline from the aprilia forum pretty easy too, as i'm not keen on pulling the engine just yet.

    you may also be interested in the best high MPG fairing shape for inline 2 wheelers ever produced by following the link to craigvetter.

    http://www.craigvetter.com/pages/470MPG/high mileage fairing.html

    click on the "fuel economy" circle at the top of the page.

    i may do one of those in the future myself.

    Last edited: Jun 18, 2011
  5. nwohater

    nwohater New Member

    Thanks. I've seen craig Vetters works, and just looked again and none of them do for me what the aerocoupe trike pic does on the bluesky page you listed.

    Love it.

    Even if less efficient, it would work with coroplast better than craigs compound curved stuff, just need the bluesky canopy, or maybe start with it as an open roadster.

    Coroplast and compound curves don't mix, but the only significant compound curve on the aerocoupe is the canopy. I'd like to figure out a way to diy the windshield canopy too but I can't think of one.

    I'm planning a trike like the aerocoupe anyway, not two wheels. I was thinking of starting off with the 150cc gy6 engine in the scooter I have that I never use, but since they aren't the greatest things I'd probably keep my eyes open for something better like you got when a good deal comes up on cl later.

    The gy6 I have is just a china engine but with cheap parts I can probably keep it running for a while, and it will get good mileage and speed, not great like yours but good.
  6. DetonatorTuning

    DetonatorTuning Active Member

    well since you are familiar with coroplast construction for fairings you may also know about John Tetz and his work with foam.

    google Tetz foam bicycle fairing for info.

    the aerocoupe is special for sure. check out pics of the SR71 BlackBird for obvious similarities.

    IF a guy was thinking of full FRONT and rear suspension AND TILTING tadpole the
    MC_D50TKA at scooterdepot is a cool frame to work something out on.


    Last edited: Jun 18, 2011
  7. SimpleSimon

    SimpleSimon Active Member

    Yeah, DT, I've been looking at that "poor man's Spyder" for a while. Unfortunately, the odds of my getting one are essentially zero, even at $1,500 a copy. That design would lend itself to a fully faired recumbent velomobile very readily. I envision something like a miniature version of the Riley design for the XR-3.
  8. DetonatorTuning

    DetonatorTuning Active Member

    Hi Simon,

    you might know that BSD offers the aerocoupe body and a lower enclosure for a tadpole based velo.

    it's much cheaper than the frame, belly pan, body and canopy for the aerocoupe.

    there is tons of potential for projects at BSD and in the velo market at large.

  9. DetonatorTuning

    DetonatorTuning Active Member


    estimate of complete engine assembly w/ rear wheel and tire is 75-80#'s according to Rich at HighGainTuning, who is THE expert on all things Aprilia Ditech.

    that would put a complete aprilia ditech powered aerocoupe at about 175#'s by my calculations. the stock configured scooter weighs 196#'s dry.

    the honda based velo GAINED 85#'s, made improvements in CD and gearing AND doubled the original MPG.

    this project being LIGHTER than stock, and a recorded CD of .2 is going to be real neat on alot of levels.

    i'll get some measurements tomorrow.

  10. nwohater

    nwohater New Member

    Nice! thanks. What honda based velo gained 85lb and still doubled mpg's I'd like to read up on that.

    I looked at the foam stuff, that might be handy have to look into it more.

    I'm still undecided on type of suspension, tilting seems overkill too complex and heavy for my tastes, but it needs something minimal and light and for me simple in engineering. I only have basic home powertools plus a grinder and a stick welder. I'm not one of those folks with their own machine shop or the budget for a machinist to make stuff for me. **** I'm talking about a chinese gy6 and coroplast fairing, cornering the market on cheap over here.
  11. DetonatorTuning

    DetonatorTuning Active Member

    the fella in the first link in the first post of this thread says in the last few paragraphs before the tire testing segment that his honda Innova based streamliner gained 88# and doubled it's MPG.

    earlier he has graphs and text explaining that at 55mph 88% of the resistance to motion of the average cycle is air resistance ( Cd ) and 10% rolling resistance ( Crr )

    this is why the aerocoupe is so important, it's shape produces the flat plate drag equal to a standard 4x8 mailing envelope. that's .2 Cd.

    the GM EV-1 ( 1996 ) had a Cd of .195 there are only a handful of other vehicles ( all special one off mega buck experimential ) to have ever done better than that. you can read up on this at:


    the idea of a .2 Cd vehicle at or below it's driveline donors original weight is truely intoxicating and absorbing to me.

    i proved some of this theory yesterday on road segments that i travel to and home from work. i usually sit straight up on the scooter and use a specific marked position of throttle. yesterday i used the same throttle but "tucked" down using the back portion of the seat and having just my eyes and top of my head above the windscreen just behind the bars ( elbows and knees in as close as possible ) and gained 7MPH from removing just that amount of frontal area, and we are talking about removing 2/3 of the frontal area of the bare scooter itself and improving the exit flow ( no suction drag ).

    i'll get some measurements and pics of the basic scooter up this afternoon.

    Last edited: Jun 19, 2011
  12. DetonatorTuning

    DetonatorTuning Active Member

    scooter and aerocoupe pics

    ok i have some pics from the aerocoupe assembly manual to provide a reference to some pics of the aprilia sr 50 ditech.

    #1 side of aerocoupe
    #2 scooter with tapeline effort to show aerocoupe outline against scooter, this is a ROUGH representation of the length and height of the aerocoupe compared to the scooter. the bed rails are situated to show the actual bottom line of the aerocoupe, yes that's 2" off the ground. and are the 100" length of the aero body. the front of the tape line corisponds to the front of the aero's body relative to the aero's front axle ( 29" ). but as you can see i didn't have what i needed to get the nose slope right, it should go up much faster. perhaps someone who is a good photoshoper can do an overlay with pic #1 for us.
    #3 pic of front fairing of scooter revealing horrible design flaw resulting in giant air brake.
    #4 front brake
    #5 rear brake
    #6 throttle body
    #7 fuel rail on front of engine head

    length of engine from fuel rail to the back of rear tire 32"

    scooter has a 3" stretch kit and a wheel base of 54", with driveline in aero the wheel base will be atleast 57" possibly 60".


    Attached Files:

    Last edited: Jun 20, 2011
  13. nwohater

    nwohater New Member

    Nice, that aerocoupe is really small and low isn't it. I read they had a stock 1.5" ground clearance, you're going for 2, but what about speedbumps and stuff? Almost need some small airbags to pull that low of a clearance off and still not high center and scrape the ground all the time.

    My china scooter has the same useless air scoop in front also. Form over function.
    I think it's supposed to mimic the lines of a superbike, nevermind that the engines aren't even there in front and so it makes no sense.

    That scoot looks like it's body is in good shape, you should be able to recoup a lot of your build costs selling the body panels and stuff you don't need if you remove them carefully without breaking or scratching them up and ebay them. People are always looking for body panels and small parts. You might be suprised what they're worth.
  14. DetonatorTuning

    DetonatorTuning Active Member

    the 2" ground clearance is the way the aero's are set up for racing and is the result of using 16" bicycle tires up front.

    i'm using full motorcycle sized 16" Tomos moped mag wheels on the front so i'll have a gc of 4.5".

    there are no speed bumps or dramatic irregularities on the roads i intend to travel. don't forget, i'm building primarily a work commuter, though i may run some errands too ; ))

    yes, i hope to sell off everything that doesn't make it onto the areo. the salvage 16" Aprilia Scarabeo Ditech rear wheel and tire i just bought cost me $150. new the wheel alone is $500+. yikes !!!!!

    Last edited: Jun 20, 2011
  15. nwohater

    nwohater New Member

    That's funny $500 for a scooter tire and wheel. :) I knew the parts would be expensive but ****, all sense of scale is lost on some of these scoots.

    Whatever I build I'll want to ride all over the place, especially if it gets over 100+mpg. I'm the type who will hop on my motorcycles and ride half a day or more just for the fun of the ride, without any destination, and do that pretty often. Something like this I'd like to rig up a superlight trailer and run to the coast just for some fresh seafood or fishing or to catch my own crab. And I'll want it to be a grocery getter and etc, so it pretty much needs to go anywhere and everywhere. I hope 150cc will handle going up and down the mountains with a tiny aerodynamic trailer and about 50lb load.
  16. DetonatorTuning

    DetonatorTuning Active Member

    i fully understand about wanting to go places and do things just because. believe me i was there, lost the shirt, but still have the scars.

    i'm a 57 yr.old married guy ( 30 yrs. w/ one wife, thank you ) with a day job, 2 hobbie buisness's, a live in 13 yr. old grandson and a life full of friends and average joe activities.

    if i don't ride to work i don't get to ride it's that simple and i intend to ride and have fun doing it.

  17. nwohater

    nwohater New Member

    42, divorced, lost the house, the dogs, the two new cars, and then dumped the fiancee I had after the ex wife. But at least now I have all the time in the world to play, provided it's cheap play hence wanting super gas mileage. Unemployment doesn't pay well, at this point it doesn't pay at all, but the schedule is good. Good times good times.

  18. Alaskavan

    Alaskavan New Member

    150cc would be overkill (not to mention probly illegal). I run a 90cc Lifan on my trike, and without the aerodynamics you guys are talking about, it will cruise all day at 30+ mph, gets well over 100 mpg, and climbs grades with ease.
  19. DetonatorTuning

    DetonatorTuning Active Member

    Van !!

    great to hear from ya.

    only been 5-7Heaven on a guest pass respond to my current rantings so far.

    excellent point about the 150 engine, i've seen those things on various forums being shoved under everything but a desk chair so far.

    probably not really even equal build quality as your Lifan though.

  20. nwohater

    nwohater New Member

    We're talking about two different animals here alaska.

    I realize this is a bicycle forum and I also am planning a 35cc city trike, both have a lot in common but I'm not talking bicycle speeds at all with the 150. I'm talking freeway speed 3 wheel aerodynamic scooter based on motorcycle/scooter running gear, that gets over 100mpg at full freeway speeds and can go up and down the mountains at speed. It'll be licensed, tagged, and insured same as the scooter it comes from...

    Like this, but faster and safer and with a shell:

    I already have the 150 scooter and never use it, hence the reason for making a bigger trike than the bicycle one especially after seeing what detonator is working on and falling in love with the aero body shape he's chosen. It would turn a completely unused scoot that I always pass over for my 250 bike into something I might ride more than the 250.

    The 150 is a chinese piece of junk I know, I just already happen to have it. I only paid $120 for the whole thing new because it didn't run when I bought it, but I'll probably get several thousand miles out of it now before it's dead because I keep upgrading the parts with brand name stuff as I fix it. It only has 50 miles on it so far and I've already replaced the carb, cdi, and magneto and done a valve adjust to fix it and make it more reliable. I will probably replace the timing chain also before trying to go any distance on it. If I'm lucky I'll get $200+ back from selling the scooter body panels and other parts I don't need to build the trike, and it will basically be a free engine at that point. (I still have less than $200 in the whole thing.) They're easily replaced if it blows up, so no big loss either way.

    I bet the next question is safety. Well I'm heading in this direction now. This simple x-prize vehicle uses a 50cc gy6 and a foam core laminated fiberglass body and does over 60mph:

    In use:

    Super scientific crash tests:

    I'm looking into something like that, but with better looks and the tadpole/reverse trike shape of the aerocoupe. Might have to use carbon fiber laminate instead of fiberglass though, or coroplast on parts to keep weight down, not sure still researching my options.

    I realize this vehicle is a bit out of the scope of this forum, but it shares so much in common with lightweight trkes like what you guys are working on that much of the technology is the same, and I'm getting a lot of good ideas from here. I probably will have pedals in it, if the weight can be kept low enough for them to be useful at all.
    Last edited: Jun 21, 2011
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