VP-21A Single Seat / Yankee Luciole

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
6,815
Location
US
We keep talking about wing span all by itself, but isn't there a ratio of length to wing span that doesn't work? When I look at aircraft that are really short, like 15 feet, they don't look right with wings much longer than 18-20 feet. Is it just me? We get into flying wing territory at some point.
To get desirable static and dynamic stability, the tail volume would need to increase a bit. It is generally "cheaper" (weight and drag) to get that tail volume with a little more fuselage length than by adding area to the horiz and vertical tail surfaces, so that's what most designs do.
 

Topaz

Super Moderator
Staff member
Log Member
Joined
Jul 29, 2005
Messages
14,752
Location
Orange County, California
To get desirable static and dynamic stability, the tail volume would need to increase a bit. It is generally "cheaper" (weight and drag) to get that tail volume with a little more fuselage length than by adding area to the horiz and vertical tail surfaces, so that's what most designs do.
My avatar being a perfect example of this. ;)
 

Victor Bravo

Well-Known Member
HBA Supporter
Joined
Jul 30, 2014
Messages
9,679
Location
KWHP, Los Angeles CA, USA
The DA-5 is a great achievement. But the A-65 is not what I was looking to power this with. I'm trying to get down to half of that fuel burn, which the V-twins and some other engines will do. The DA-5 is a little too "rough" for what I'm dreaming about, too heavy, etc. The DA-11, Moni, and Luciole are a lot closer to what this was about.
 

patrickrio

Well-Known Member
Joined
Aug 15, 2020
Messages
352
Hi, I have done some research previously on the DA-11, Luciole and Moni. I know that many people already know the info I am listing below, but thought it might be helpful to have it in one place for comparison.

DA-11 per manufacturer listed specs has 200lbs available for pilot, baggage and fuel. Manufacturer listed stall speed is 60mph but that was met with only a few gallons of fuel in the tank and a 130lb-ish pilot and no baggage. 18 HP per manufacturer. Only one built, only flown by test pilot and mostly only flown during test phase and then hangered. Designer/manufacturer Davis knew it was a bit more demanding to fly than a plane should be for normal pilots. Manufacturer lists top speed as 155mph(once again calculated with low fuel weight, low pilot weight and no baggage)

Luciole has 227lbs available for pilot, baggage and fuel per designer specifications that are easily verified from flying examples. I did not find a designer number for stall speed but have seen owner listed stall speeds ranging from 41mph to 52mph. Designer lists airplane as having 25HP. Designer lists top speed as 120mph. By most accounts it is a nice flying aircraft that is ok for normal pilots to fly.

Moni with KFM 30HP engine has 240lbs available for pilot, baggage and fuel per designer specs. Once again, I could not find stall speed listed by designer. my observed owner listed stall speeds range between 38 and 42mph. Top speed of 120mph. People say it flies nice, but there are people who recommend glider training especially for spin stall training as it has had a few crashes from wing stall in tight turns like gliders in thermals.
 

rv7charlie

Well-Known Member
Joined
Nov 17, 2014
Messages
1,942
Location
Pocahontas MS
VB,
Not trying to change your mind about what you want, but it's worth remembering that fuel burn is largely what you make it. When I was a student pilot & looking for my 1st airplane, a guy offered me a share in a Cherokee 140. I told him I couldn't afford the fuel burn; twice a C-150's. He said that he flew it x-country all the time at about 4.5gph, at about the same speed as a C-150.

30 years later, my RV6/180hp/10-11gph airplane flies around 2-up at low altitude all the time at ~5.3gph & ~135mph. Something in the C65hp range, with electronic ignition and decently matched fuel flows should easily achieve 2.5-3 gph in a smaller airframe, at the same speeds you'd fly with a V-twin. BSFC tends to get better at lower power settings (within reason, of course).

Again, not advocating for a C-65 or anything else. Just offering 'perspective'.
 

Victor Bravo

Well-Known Member
HBA Supporter
Joined
Jul 30, 2014
Messages
9,679
Location
KWHP, Los Angeles CA, USA
Agreed 100%, reduced power and better fuel/spark control can do wonders. (I actually squeezed into the back of Klaus Savier's O-200 Vari-Eze once, and IIRC he was getting it down near 2.5 or 2.7 gallons an hour at well over 170 MPH.)

I love the old A-65 as much as anybody here. May they run forever :)

Part of my ridiculous thinking has to do with storage footprint and small airplanes. I have a 42 x 36 foot T-hangar, and it contains a Cessna 172, a wing-folded Ridge Runner 2, an RS-15 sailplane fuselage pod, my hangar landlord's 69 Volkswagen... and 5.9 x 10^6 cubic yards of "stuff" in it (a very modest EAA homebuilder shop, some raw materials, boxes and boxes and boxes of s**t from my life, a fridge, a couch for airport bum meetings, and is also an FAA-PMA approved manufacturing facility.)

So anything that I consider seriously building has to fit over, under, or inside of a very small space. Even a DA-11 or a CriCri would have to be hoisted up above the fuselage of the 172, and that would take moving the shop lights around. Not kidding :)

The truth is that I need a bigger hangar. My delightful wife says no problem, so long as the bigger hangar has room in it for me to live there too. She's not kidding either :(
 

BigL

New Member
Joined
Jun 25, 2021
Messages
3
There is a design guideline called Stability Factor with equations for Horizontal Tail surface sizing (Vh) and for Vertical Tail surface sizing (Vv). The discussion on Wing Span relates to (Vv) for vertical surface size. Increasing the span requires a larger Vertical Tail area for a given Tail Arm length. If the Vertical Tail isn't to look too big then the Tail Arm has to be increased. Unless you want a plane that yaws wildly.
 

mcrae0104

Well-Known Member
HBA Supporter
Log Member
Joined
Oct 27, 2009
Messages
4,079
Location
KBJC
"A man is kidding his wife that with all these electronics Big Brother is always listening. Then he laughs...his wife laughs...Siri laughs...."
1626414158660.png

I'm a little late to this thread. Lots of folks discussing an 85% solution but <2% really working on it.

My avatar being a perfect example of this. ;)
We can't even see your wingtips in the avatar--for all I know, you fly with an infinite wingspan (might explain your occasional long absences ;) ).
 

Attachments

Bigshu

Well-Known Member
Joined
Jun 7, 2020
Messages
572
There's another thread on this, but the Hummel annual gathering debuted a V-twin powered aircraft, which for the purposes of this discussion, bears a closer look.
 
Top