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Jim Williams

Member
Joined
Sep 17, 2005
Messages
14
Location
Atlanta ga.
Hello to All,
Iam new to this list, but I am not a new homebuilder. I have built two Midget Mustangs and started a third. But like many aircraft homebuilders I would like to build my own design. Iam at the age now where I don't care to carry passengers. I what a single seat A/C. I don't care to go fast. Maybe an all metal low wing VW powered taildragger. It would have to have a big cockpit for my big butt. I know there are aircraft plans and kits out there that fill my needs, but are not my own design. The aircraft I am thinking about that is close to my needs is a all metal Colibri MB2. I know it is made of wood, but my close copy would be all metal.
Maybe a little back ground would help. I am a retired Aerospace engineer with 45 years in aircraft structures. I have worked for Grumman and Lockheed Martin. My last job was working on the F22 before retiring in 2000.
The help I need would be finding plans for the Colibri MB2 can anybody help.

Thanks
Jim Williams
 

CAB

Well-Known Member
Joined
Nov 26, 2004
Messages
128
Location
Colorado
Also...

You might try contacting the Hummelbird crowd somehow. I have heard of mods for larger-than-FAA-standard people (like me!).

CAB
Bearhawk#862
 

bill k

Member
Joined
Oct 1, 2007
Messages
20
Location
sunman indiana
hey jim i agree with sakota the plane for you is the bk flier. its mine as soon as i can get plans and some money. 6'4" pilot, 250 lbs. 30 # baggage, 135 top end, 45 landing and build for 7000. can't beat it. bill k
 

keith103

Well-Known Member
Joined
Nov 12, 2013
Messages
121
Location
Aurora, Denver,CO
Hi Jim,
Old thread this one, but I also would like to build my own design. Is it a do-able goal ?
By the way, you started off saying you wanna make your own design, but then you asked for plans.
I was thinking that if it is your own design, then you gotta make your own drawings based on your own design !

Any way, what is the latest on your design ?
I am just looking around to see if making one's own design is practical and (more important) will it be safe.
Thanks
Keith
Denver
Dec 2013
 

dcstrng

Well-Known Member
Joined
Oct 17, 2010
Messages
913
Location
VA or NoDak
Old thread this one, but I also would like to build my own design. Is it a do-able goal ?
By the way, you started off saying you wanna make your own design, but then you asked for plans.
I’d guess there are very (very) few potential homebuilders who haven’t thought about designing their own plane at one time or another (all those creative genes looking for an outlet). Typically there is some distinctive set of esthetics a builder doesn’t see in the market, or possibly a unique flight envelope, or perhaps they like a specific style but don’t find it optimized for their proposed flying habits (guilty !!).

Whatever the case, I’ve sketched up several dozen different rib-templates, doodled my way through a similar number of accommodation sketches and calculated tail-volumes, etc., etc., run countless spreadsheets predicting the characteristics of my fantasy-flyer du jure… was just sitting in a (boring) meeting yesterday doodling up the mechanism and working the trig for slotted flaps (no fair telling on me…).

Where I fall short is I’m not an engineer and am always leery about my ability to get the structure itself correct (and sense I purport to fly in the things, this seems critical…). So inevitably I now start with a proven design, where structurally it is a know quantity…

Nonetheless, that is not all bad – indeed, it is pretty much what the certificated aircraft world does as well and is certainly the case many times over in the homebuilt world… As I recall the BK-1 started off as a highly modified Hummel for a larger pilot, which Mory started off as a (if my geriatric memory is reliable) as a highly modified Windwagon of something… Pretty much all the Wittman two-place birds are related under the skin, and the Monnett family of birds (from Sonerai through to the current Sonex family) bear many similarities even though structures, materials and accommodations have changed – but if you follow you’ll see the changes are evolutionary and iterative, not wholesale or revolutionary…

Although bit of a logical stretch, even Rutan was simply mating a proven (outside aerospace) construction technique to an aero-form that would have seemed quite conventional to the Wrights or Glen Curtiss…

Don't know about Jim; but I’ve got an embarrassingly large library of plans to feed my “design day-dreams” and I’d suspect many real designers do too…
 

Dana

Super Moderator
Staff member
Joined
Apr 3, 2007
Messages
9,336
Location
CT, USA
I doubt you'll get a response from the original poster; it's been over 4 years since he's been seen here.

Dana

There are 3 kinds of people: those who can count & those who can't.
 

keith103

Well-Known Member
Joined
Nov 12, 2013
Messages
121
Location
Aurora, Denver,CO
Thanks, for your suggestions.

At 59 yrs of age, I have a low-back problem, due to which none of the usual Pt 103 designs suit me.
Most of these require that I sit with my legs almost flat / stretched out straight ahead.
My medical condition requires that I sit with my feet about 15 to 18 inches lower than my thighs, to be comfortable.
That is what caused me to initially look to modify only the cabin floor level of the existing designs to change the seating position.

So I started doing that and somewhere along the way, I said if I have to change this or that,
why not just start from scratch, and make it all new.

Yes, any design I may come up with, will certainly not be revolutionary.
And this is what makes it probably do-able - there is no need for me to invent a new type of airfoil,
there are countless trusted designs flying out there. It will probably be a mix n match of various
proven techniques and designs which are already flying out there.

My feeling is one has to have a good sense of ( or rather a feel ) for structural issues.
And I am not talking about the mathematical equations, but a structural feel / sense.
I already read Dan Raymer's design book.

If one is making a generic kind of 3 axis ultralight, I think is do-able, but need to be aware it could be faintly risky too.

My post was to find out if any of the members have already done this, and if so what their advice would be on this subject.
Thanks
Keith
 

bmcj

Well-Known Member
HBA Supporter
Joined
Apr 10, 2007
Messages
13,495
Location
Fresno, California
Thanks, for your suggestions.

At 59 yrs of age, I have a low-back problem, due to which none of the usual Pt 103 designs suit me.
Most of these require that I sit with my legs almost flat / stretched out straight ahead.
My medical condition requires that I sit with my feet about 15 to 18 inches lower than my thighs, to be comfortable.
That is what caused me to initially look to modify only the cabin floor level of the existing designs to change the seating position.
It seems like you could get the same effect (sitting/leg posture) by tilting the entire seat backward enough to put your legs at the correct relative angle. Your legs might not be "lower", but at least they would be in the correct geometry.
 

keith103

Well-Known Member
Joined
Nov 12, 2013
Messages
121
Location
Aurora, Denver,CO
It seems like you could get the same effect (sitting/leg posture) by tilting the entire seat backward enough to put your legs at the correct relative angle. Your legs might not be "lower", but at least they would be in the correct geometry.
I thought of that at first. Unfortunately that will not work for me. In 2008 I had a disc rupture at the 5 th vertebra from the bottom, which never fully healed, but somehow I am managing to keep the situation under control by doing physiotherapy and avoiding surgery. I avoid seatback reclines of more than 10 degrees. Thanks for the thought.
 

Vipor_GG

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Joined
Jun 8, 2013
Messages
850
Location
Cayce, SC / USA
I thought of that at first. Unfortunately that will not work for me. In 2008 I had a disc rupture at the 5 th vertebra from the bottom, which never fully healed, but somehow I am managing to keep the situation under control by doing physiotherapy and avoiding surgery. I avoid seatback reclines of more than 10 degrees. Thanks for the thought.
I feel your pain (literally I have ruptured disk between L4-L5). There are so many things I can no longer do. I can only sleep on my right side or my back and must alternate between the two. It is a pain like no other and set off by many things. I had one injection 3 years ago and therapy, now as long as I don't do stupid things and keep up the exercise I do pretty well. For me sitting reclined is okay as long as I have a small pillow for lumbar support, but upright is better. Have you tried sitting on a ball while at a desk, watching TV, or even eating? It forces you to sit with correct posture and strengthens you core muscles. Best of luck in you quest for a small plane that fits.
Billy
 

wizzardworks

Well-Known Member
Joined
Nov 8, 2011
Messages
273
Location
murfreesboro NC USA
tnCAAW1TNDbulkheadLocations.jpg Keith, Normally in the initial layout a sketch is made of the things that are relatively non negotiable. Things like a pilot and passenger, the engine and such. Then a shape fitted around these fixed
items allocating volume for the control panel, a first GUESS about spar position and a looks appropriate tail. Attached is such a sketch from the extensive razorback thread in the new technology threads. If you have a design you could be interested in you might look at the 3 view side profile of it and overlay your needed seating position. If it is a low wing the changes would be to the canopy top and turtle deck areas. The Cg of the pilot would ideally remain the same but could result in the control panel being shifted forward slightly. Larger imbalance could be resolved by changing the length of the engine mount/prop spacer and possibly the cowl length. Building a tandem seat plane as a single seat would be fairly simple as far as cabin reconfiguration goes. In addition to low wing monoplanes you could look at some biplanes with tandem seating, particularly those with a rear pilot position. And then there are the powered parachutes and rigid wing trikes. If you can select a candidate and post photos or drawings it is likely forum members will have lots of ideas. There is a thread somewhere about someone with a seat built on a power seat out of some car that raises him up and out or down to flying position. Seems like travel is 15 seconds best I remember.

wizzardworks
 

keith103

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Joined
Nov 12, 2013
Messages
121
Location
Aurora, Denver,CO
Thanks for your ideas and thoughts. I guess it is time for me go back to drawing the sketches. I have not thought about the design in detail, except that the seating position should be more upright and the seat itself should be about 12 to 15 inches above the cabin floor. This also means more form drag, which probably cannot be helped. There are many proven ultralight designs I could take a close look at, to get ideas.
Will get back as the thought process and concept evolves.
 

TFF

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Apr 28, 2010
Messages
13,463
Location
Memphis, TN
My question is if you cant recline to get the feet below the hip, how will you get the leverage to push the rudder pedals? Most rudder is combo of ankle and knee movement. If you shins are straight down its more of hip shuffle movement. Team Airbike might be adaptable.
 

keith103

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Joined
Nov 12, 2013
Messages
121
Location
Aurora, Denver,CO
Hi, Probably I did not correctly explain what I had in mind.
The posture I am comfortable with, is like the driver's seat in one of the small SUV's like Honda CRV.
Sitting in an SUV, I can comfortably apply brakes and switch my feet from the throttle to the brake. Hence in an airplane, this posture will give enough leverage to actuate the rudder pedals too. When I sit in my Honda CRV, my butt is about 13 inches from the cabin floor, and the portion of the leg from knee to ankle is not horizontal, but at angle of 45 degrees tilted down from the horizontal. I would like to replicate this exact posture in the cockpit. If possible I would like to raise the seat by an inch or two, to 15 inches above cabin floor.

In a sedan like Camry, the butt sits lower and closer to the cabin floor, the ankles are more raised in relation to the butt and knees, so my back hurts in longer drives.
 

TFF

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Joined
Apr 28, 2010
Messages
13,463
Location
Memphis, TN
I get what you want. Airliner cockpit seating. Although most pedals seem to be raised to keep the sports car feel. The thing is you need lots of cabin height or have your feet dangling out of the normal cabin as you know all these sport planes are pretty compact. 15" height is 10" higher than a C150. pretty much 172 ceiling height with the seat jacked up. Air-Bike 103 has the feet low but its exposed.
 

Vipor_GG

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Joined
Jun 8, 2013
Messages
850
Location
Cayce, SC / USA
In a sedan like Camry, the butt sits lower and closer to the cabin floor, the ankles are more raised in relation to the butt and knees, so my back hurts in longer drives.
Same with my F-150 and my wife's T-bird, but it's more my hip hurting due to the pressure on my sciatic nerve.
 
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