www.recumbents.com - Shell Design Software
www.recumbents.com
www.recumbents.com
Home | Profile | Register | Active Topics | Members | Search | FAQ
Username:
Password:
Save Password
 All Forums
 www.recumbents.com
 Technical / Bike Building
 Shell Design Software
 New Topic  Reply to Topic
 Printer Friendly
Previous Page | Next Page
Author Previous Topic Topic Next Topic
Page: of 23

shooky56
recumbent guru

USA
545 Posts

Posted - 10/08/2015 :  18:37:51  Show Profile  Reply with Quote
lol, only us old guys know! Not to make this into facebook but a couple interesting stories happened around that airplane. During the Nixon wage and price freeze in 1971 (by then we had graduated to hang gliding), one of the suits brought was over that airplane's price being raised. Obviously the kid that noticed it didn't do anything but probably had lawyer parents out to make a point.

Another story involves my uncle. He was friends with the dime store guy in Bentonville AK, they drank coffee together in the morning during the week. That dime store didn't have that plane, my uncle said he'd tell that guy to have them for our next visit. You guessed it, it was Sam Walton. Sam and his brother tried to sell my uncle a couple shares (they sold 100 shares for $1000 each) but my aunt put her foot down and wouldn't let him. IIRC (from my uncle telling the story 20 years later) that didn't actually start out as a Wal-Mart but eventually became Wal-Mart.

Anyway back on topic.

Prints: I made a second paper guide and it was better but not good enough. Making a third and waiting on some parts. I contacted the printer company and they told me that yes those banner printers drift left and right but should be pretty good along the length axis. That's what I'd seen in my several dozen dry runs. Anyway I've got another idea and, when I can print my full-sized panels will test a full-sized shell (this one should be a keeper if it fits). Not long after I'm happy with sizing I'll release the latest version.





Go to Top of Page

Grant-53
recumbent guru

USA
544 Posts

Posted - 10/09/2015 :  14:15:03  Show Profile  Reply with Quote
I tend to go with a 5:1 airfoil with a 75% Kamm. What is tricky about the Varna and other speedsters is the weight distribution as well as the shape. We can test the bodies for Cd but each design is a compromise. And yes, Georgi bumblebees do fly.
Go to Top of Page

Speedbiker
human power expert

USA
3760 Posts

Posted - 10/09/2015 :  15:41:17  Show Profile  Reply with Quote
Never envoke the name of Georgi unless you have accomplishments that merit doing so. Where are these wonderful 5:1 ratio aero bodies with their 75% Kamm tails? Please post a picture of your wonderous machine so we can compare to Georgi's. It is very easy to quote various theories and mention famous names, but the proof is in what you built. Post up!

Edited by - Speedbiker on 10/09/2015 15:42:28
Go to Top of Page

Grant-53
recumbent guru

USA
544 Posts

Posted - 10/09/2015 :  19:43:35  Show Profile  Reply with Quote
My apologies. No offense intended. An aero mountain bike is under construction for street use and coast down data will be posted. I hope to break 30 mph on the flat. Perhaps a younger rider will go faster.
Go to Top of Page

Grant-53
recumbent guru

USA
544 Posts

Posted - 10/10/2015 :  06:46:02  Show Profile  Reply with Quote
The modern streamliner is a marvel. Historically aircraft design has favored the teardrop shape (Poisson function) with center of mass ahead of center of pressure. That is why the record bikes look like they are going backwards, hence the reference to the bumblebee which in theory should not fly. Georgi is a proven master in optimizing body shape for the feet forward rider close to the ground. The next logical step for the record seeking camera bike may be to try a rear facing rider as in the Vector Tandem stoker. The shape may be more stable and the drive line shortened.

I am working on the opposite end of the spectrum where low cost and crosswind stability are paramount. The current literature published (Hoerner, Specialized) has described tests indicating the 5:1 airfoil and 75% Kamm seem to be the best compromise between low drag and crosswind stability. I have plans drawn, materials collected, and the software Shooky56 has generously provided will help to further optimize shells. My health is the only limiting factor at this point. Again sorry for the misunderstanding.
Go to Top of Page

Speedbiker
human power expert

USA
3760 Posts

Posted - 10/10/2015 :  11:08:21  Show Profile  Reply with Quote
You need to take a look at Damjan Zabovnik's effort this year. He went 80 on a flat tire. I just spent an hour talking to him. Next year he will use Schwalbe One tubeless and with more refinement expects to go faster.
Also, your understanding of modern hpv design is lacking. Extensively laminar designs with their maximum half breadths at 60 to 70% back is the reasons so many liners are exceeding 80 (85?). But you won't find this info in any book. It started with Matt Weaver and his Speed 101 website (now lost, but not totally gone), and is now only found in the heads of top hpv designers. Did you notice the guy who set the record this year has his doctorate in engineering/aerodynamics? Everyone operates on a different level. But if you can't do the math, you aren't an engineer. Top liner designs are designed with math, not eyeballs. And you have to understand the physics behind that math. A university education help a lot, but isn't totally necessary. While I consider myself a good shade tree designer, I am a master machinist and fabricator. I leave the real designing and engineering to the real deal, my brother. Despite my impressive build/performance record, I don't pretend to be an aerodynamic engineer. You've never seen me post about the merits of L to W ratios, NACA foils, or Kamm tail theory. If you do so, I would expect to be impressed by what you build. Let's see the result of all this aerodynamic knowledge. Warning: I've been sticking fairings made coroplast, PETG, fiberglass, kevlar, carbon and even aluminum on bents and dfs since 1982. I've raced all of the above. I know the difference between good design/fabrication and "not". Post up!
Free advice: use the tools Wayne has created and you'll be way ahead.

Edited by - Speedbiker on 10/10/2015 11:11:55
Go to Top of Page

Grant-53
recumbent guru

USA
544 Posts

Posted - 10/13/2015 :  12:38:24  Show Profile  Reply with Quote
I agree that I have a good bit to learn about the modern record HPV shells. I have undergraduate training in fluid mechanics and differential equations. Most of my experience is with sailplanes. I put the first fairing on my Ross 15 spd after reading the article on human power vehicles in Scientific American Dec. 1983. Please understand I mean no criticism but only wish to share information and thoughts. If you know of experiments that prove or disprove a concept or technique I would appreciate the details. To date I have a nose piece and side panels made. The critical part is the tail section. I will post data as I can here first.
Go to Top of Page

Jerry
recumbent guru

USA
982 Posts

Posted - 10/15/2015 :  17:14:28  Show Profile  Reply with Quote
Grant-53, you don't need to apologise to Thom. Thom is suffering from PMS and likes to toot his own horn. LOL. I am new to bike racing and building at 63 years old. But, I too can fabricate just about anything. I have welded for over 50 years and taught welding for over 35. I can use any process of welding except what has come out in the past 9 years because I have been retired that long. Still, that doesn't mean I should go around bullying others who can't weld very well or just starting out welding. Thom, quit being so damn mean to people and cut them a little slack. That is if you want the sport of HPV racing to grow. If you are good at something, other people will tell you. You don't have to be your own cheerleader. And before you get on here and start typing, I think your bark is badder than your bite! LOL. After all, I do this for fun. If I were making a million dollars or more a year from it, then I would be more serious about it. Bike building and racing I mean! Everyone starts at the same place, the beginning. No one was born an expert. I think your intentions are good, you just express them too strongly at times. I should know, I am usually getting this advise from my wife and friends.

Go to Top of Page

Speedbiker
human power expert

USA
3760 Posts

Posted - 10/15/2015 :  18:35:42  Show Profile  Reply with Quote
Ah, ya got me Jerry! Ha ha. I ain't never built nothing. Certainly not like Grant. Grant is smart, but we're waiting for him to build something that's up to his ability. In the end, that's what it's about. Talk is cheap, build something! People who post about stuff they don't understand does nothing for the sport(except entertain Jerry). Jerry, are you a talker or a builder? You definitely gots the skills. Maybe someday I'll build something, or try to do something for the sport. Someday..... Til then, what are you building?

Edited by - Speedbiker on 10/15/2015 18:46:49
Go to Top of Page

Jerry
recumbent guru

USA
982 Posts

Posted - 10/15/2015 :  19:13:32  Show Profile  Reply with Quote
Well Thom, I was going to build a coroliner. But I think now instead, I might just make my old Phantom a little faster by buying some heavy duty spandex like Richard Myers uses on the Jester. My main problem is I am never home long enough to get things built! I have 2 Grandson's and a 3rd on the way. My wife and I go to Texas every few weeks for 2-3 weeks to visit them and my daughter. I have a Lexan front fairing and a coro tail box I built for it. I tried some very light weight spandex. It worked, but would not stop stretcting. When we get moved to Texas next year, I will restart the coro project. Maybe like you suggested, a velo, instead of a streamliner. If the velo doesn't do it for me, I'll make the streamliner. I would either refab the Actionbent or modify my Rans V2 lwb. I'll make a couple of races next year and take a good look at the fastest streamliners. I should have a good seat with them passing me so many times! LOL.

Even with the stretchy spandex with an open top and bottom, I could hold 20-22 mph on the old Phantom for a few miles. I will use supports this time and completely enclose the bike. Once I get the spandex constructed like I want it, I will have a seamstress to sew in the door zipper and the top zipper. I am also going to make some new seat stays so I can recline the Phantom seat more.

I am glad you can take a good ribbing! I can't wait to meet you and the other racers next year. Your son Charlie and Maria Parker are two of my heros. The assault on MT Mitchell in NC really impressed me. I might just have to try out a Cruzbike Vendetta 2.0. Charlie, Maria, and Larry Oslund make them look awful good!

Oh, I almost forgot. I build travel trailers for bicycles out of steel and coro. I made a Delta trike, an 8 foot high DF bike, a round ring with seat and pedals, and a few other things. Too dang old to ride that stupid ring, so I cut it up. Too many things I want to do. My can do just can't keep up with my want to! LOL.
Go to Top of Page

Speedbiker
human power expert

USA
3760 Posts

Posted - 10/15/2015 :  19:38:19  Show Profile  Reply with Quote
Yeah, it's great having the skills to make stuff. And with this site and Wayne's program the sky's the limit. I helped Richard design the Chiquita and think it is one of the great overlooked hpvs, mostly because of it's vintage engine. I hope you find time to make something fun.
Go to Top of Page

Jerry
recumbent guru

USA
982 Posts

Posted - 10/16/2015 :  03:52:14  Show Profile  Reply with Quote
Richard is my inspiration for wanting to start racing, him and Tyger Johnson. Wayne has spent a lot of time on his program. He and Warren are to be commended for their time and effort. When I do get the time, I will use Wayne's program to make a decent nosecone. Richard says a good nosecone design helps with speed. I have to go and get ready to go to the airport. Picking up my daugther and grandson's.
Go to Top of Page

Speedbiker
human power expert

USA
3760 Posts

Posted - 10/16/2015 :  05:45:19  Show Profile  Reply with Quote
Richard is very sharp. I wonder who the crazy bird is that got him into all this streamliner stuff?
Go to Top of Page

Grant-53
recumbent guru

USA
544 Posts

Posted - 10/16/2015 :  14:36:55  Show Profile  Reply with Quote
I was going to say a Snickers depletion. LOL My late father-in-law was a self taught mechanical genius with patents instead of college degrees and a top regional motorcycle racer with dozens of trophies. His walls were covered with pictures of his family and the trophies stashed in the attic. Either people loved him or couldn't stand his bluntness. We really do want to promote the practice of human powered vehicles.
Go to Top of Page

PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 10/18/2015 :  14:35:13  Show Profile  Reply with Quote
Everybody eat a Snickers, too many Joe Pesi, Don Rickles clones.
Go to Top of Page

Grant-53
recumbent guru

USA
544 Posts

Posted - 10/18/2015 :  17:57:25  Show Profile  Reply with Quote
Amen. Would like to meet as many of you fine folks as possible in person. In the mean time I will get busy on cutting and gluing.

Edited by - Grant-53 on 10/18/2015 18:08:10
Go to Top of Page

Balor
recumbent guru

Russia
514 Posts

Posted - 10/23/2015 :  05:03:34  Show Profile  Reply with Quote
Greetings! Cannot thank you enough for all the effort, I'll surely be using this programs to build my own practical (brevets, touring) velomobile. I'm from Russia, so bad weather protection and protection from being run over by a car (happens way too frequently here, one of my friends was killed by a drunk driver on the same brevet I've participated) is extremely desirable.
I'll be using DIY CNC foam cutter, dense styromoam cut into 4" vertical slices (not as a plug, but structural, for impact protection like bicyle helmet - will leave about 1", maybe more), polyuric ('truckliner') coating over it and basalt cloth for internal reinforcement.
This is where I've got the idea:
http://www.recumbents.com/wisil/costin/swift/default.htm
Your website is truly WONDERFUL treasure pile of knowledge.

Will likely go 'f40' route by having separate front cone and tail section fairing, with removable spandex middle section.
It would likely be FWD/MBB too, I have RWD and FWD and I find power transfer in MBB to be significantly (like, 20%!) better for me, likely because I have a relatively fat back and bottom, but high power output, hence viscoelastic losses occur when I mash pedals (damped oscillations between my back and seat, and hysteresistity of fatty flesh is about 0.2).
With MBB you can do a good job of pulling on the handlebars instead of pushing against the seat, which is much more mechanically efficient (for me, at least... but I lost all hope of being thin any time soon, despite about 10k kilometers a year mileage).

Edited by - Balor on 10/23/2015 05:09:33
Go to Top of Page

harv
recumbent enthusiast

389 Posts

Posted - 10/23/2015 :  05:41:41  Show Profile  Reply with Quote
Balor, would you have an enormous nose to fully cover the sphere of movement of a MBB, or would the nose move with the BB? I don't either would be optimal and a noving nose could be fatal.
Go to Top of Page

Grant-53
recumbent guru

USA
544 Posts

Posted - 10/23/2015 :  06:05:18  Show Profile  Reply with Quote
One way to prevent neck injury in a crash is to attach the nose section to rigid side panels which would transfer energy to the seat back. Leave plenty of crush space between the nose and your chest.
Go to Top of Page

Joel DIckman
recumbent enthusiast

USA
129 Posts

Posted - 10/23/2015 :  07:54:18  Show Profile  Visit Joel DIckman's Homepage  Reply with Quote
quote:
Originally posted by harv

Balor, would you have an enormous nose to fully cover the sphere of movement of a MBB, or would the nose move with the BB? I don't either would be optimal and a noving nose could be fatal.



It can be done, and old-timers like me will remember Tom Traylor's MBB front wheel drive bikes, some of which were enclosed in fairings. Tom's Critical Mass bike used the Lightning F40 approach of separate front and rear fairings connected by a Spandex middle section. There are some pictures here:

http://chrisbroome.com/traylor.html

Most recumbent riders associate moving bottom bracket front wheel drive bikes with Cruzbike, which has built a business selling them. But Traylor deserves credit for being the pioneer of this idea. Does anybody know if Tom is still among the living? Or has he departed for that beautiful velodrome in the sky?

Safe riding,
Joel Dickman
http://lightningriders.com

These three prevent most accidents: seeing, being seen, & (usually) common sense.

Go to Top of Page

shooky56
recumbent guru

USA
545 Posts

Posted - 10/23/2015 :  08:43:30  Show Profile  Reply with Quote
Thanks Balor, you're welcome for my part of it and good luck.

It's funny about the foam behind the back/neck/nead. That's always been one of my thoughts too and have emailed my riding buddies about it often. Never thought about covering it in that stuff, actually had thought of using Kevlar epoxy sealed at the seams but left un-glued for the rest just to keep the foam a little more "together" during rear impact. But that topic needs a lot of research as to the best foam density etc. In recent months my thoughts on that topic have been more along the lines of commandeering an auto air-bag system... more study needed there too; only about a jillion details that can be goofed up. Can see the headlines "Man's airbag snaps neck from behind after crossing RR tracks!". But I digress.

Nose cone on an MBB: That one worries me, if you do this might I suggest you test it in the wind in a safe (traffic free) place?

It all sounds cool, you'll have to start your own build thread so we can "watch"! That's an interesting thing you bring up about fat hysteresis.




Go to Top of Page

Speedbiker
human power expert

USA
3760 Posts

Posted - 10/23/2015 :  09:24:38  Show Profile  Reply with Quote
I met Tom Traylor at the 1991 IHPVA, Joel must have been there too. I used to be able to find Tom's website, but now can't. If he had died I would have expected a post from Jim Parker who readily credits Tom for the mbb (he patented it). Anway, his streamlined mbb shows our new Russian friend that his idea is viable.
However, even a foam core shell only offers a 300 pound (total weight) velo so much protection against from a 4500 pound automobile. Many of us surly remember Joe Kokanowski's(sp?) attempts, and exciting crash tests, to build a liner that was safe from cars. Remember his broken hip after a car hit him? Perhaps your safety is increased slightly, but the physics are still very against us.
Best regards to Balor!

Edited by - Speedbiker on 10/23/2015 09:26:18
Go to Top of Page

Grant-53
recumbent guru

USA
544 Posts

Posted - 10/23/2015 :  11:13:45  Show Profile  Reply with Quote
Tom's Critical Mass II bike looks like it is good starting point. If the nose cross section is heart shaped and round as in Shooky's rib panels the side wind effects would be minimized. To accommodate the MBB movement the side panels might be hinged front and back. I'd try it with a model. If that is not feasible concentrate on protecting the hips, kidneys, shoulders, and head. A seat belt would help too. The Society of Automotive Engineers would have a number of papers available on crash testing motorcycles. Shooky, I was thinking about the top of the nose impacting the throat. Head and neck injuries are by far (90%) the most common cause of death for upright cyclists. Sheet aluminum does not splinter the way typical fiberglass does. Lots to consider. Best wishes Balor

Edited by - Grant-53 on 10/23/2015 11:18:06
Go to Top of Page

Balor
recumbent guru

Russia
514 Posts

Posted - 10/23/2015 :  11:14:59  Show Profile  Reply with Quote
quote:
Originally posted by Joel DIckman
http://chrisbroome.com/traylor.html



Yes, this is exactly what I've meant! Too bad that all his sites are unavailable :( Anyone have more data saved, perhaps?

After all, I need a practical vehicle to shield me from elements and glancing hits. I do not expect to survive a high-speed collision, but at least 'full moto suit' level of protection would suffice... and besides, a broken bone or two sure beats being dead and pulped.
I love cycling and I think that 'things worth living for are worth dying for', but it does not mean I am willing to take unnecessary risks, only necessary ones :).
And besides, while I'm reasonably powerful for an amateur (about 250-300 watts FTP, varies though the season), very heavy shell would make hill climbing too much of a chore.

Btw, I've had to switch my 'Location' to England for it to work, just like Shooky56 said.
Go to Top of Page

shooky56
recumbent guru

USA
545 Posts

Posted - 10/23/2015 :  11:20:35  Show Profile  Reply with Quote
Hey Thom, look at the link posted by Joel. Is that the site? May not be Tom's but perhaps Chris' hosting of the same? Never saw the original so I wouldn't know.

Physics: You're dead right on that (no pun intended). Maybe when GM is making these, they can figure it out. As Joel's message says, "These three prevent most accidents: seeing, being seen, & (usually) common sense.". Our best air-bag is not getting hit in the first place. Tell you one thing, I went from being a no-mirror-a-tall guy to actually having a couple of attention getters forward (usually just bumps) because I'm tunnel visioned on my mirror.

Go to Top of Page
Page: of 23 Previous Topic Topic Next Topic  
Previous Page | Next Page
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
www.recumbents.com © 2017 www.recumbents.com Go To Top Of Page
Snitz Forums 2000