Wittman Tailwind modified to meet E-LSA?

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

mk3041

New Member
Joined
Sep 13, 2020
Messages
2
I will make somebody a heck of a deal on a Nesmith Cougar project if you want to try for LSA, but you'll have to use a different wing like the Daphne.
Have documentation, but the registration has expired.
Mcmarkwill you please PM me with more information on your Cougar? Thank you.
 

stanislavz

Well-Known Member
HBA Supporter
Joined
Aug 21, 2016
Messages
952
Location
Lt
However the zenith will take off and land a lot shorter than the Tailwind.
Yes, if engine is still running. But on this topic - if we have boxy fuselage and its centerline is parallel to flying path / zero angle - it is negligibly worse than circular shaped one. If corners are rounded - it is close as it can be, and you make it smaller - better internal space using.

But if you left it sharp cornered and with center line like in Zenith - you have vortexes in wrong space and wrong time. But Zenith cant have it center-lined - its need it to achieve proper aoa for slats to work.
 

DeanCopley

New Member
HBA Supporter
Joined
Feb 27, 2021
Messages
1
Lotsa misinformation here, so let me try to clarify (without adding more misinformation...):
* A Sport Pilot can fly *any* airplane that meets LSA speed, weight and other criteria. That includes Standard Category and Experimental, Amateur Built. (Absolutely positive on this one);
* A plane that has been certified to numbers beyond LSA cannot have the paperwork re-done to comply with LSA numbers (pretty sure on this one);
* E-LSA means that the airframe manufacturer has jumped through the hoops to demonstrate that the airframe complies with LSA standards, and has put out a kit so that the airframe can be built outside the factory. And, that kit has to be 100.0% conforming to factory specifications when built, including engine, prop, avionics, etc. However, once built to 100.0% spec and flight tested, it can then be modified. (Positive on this one);

So:
* Join EAA
* Read the regs, they're not that hard to understand.

Be safe, be well!

Ed
Would I be correct in saying that, most of the parameters( stall speed, level cruise speed, empty weight, gross weight) for an EAB are calculated at the end of the build and during the 40hr test flying?Wouldn’t it be at this point that you would determine say the stall speed and then you would know whether it meets the 45kn LSA criteria?
 

BJC

Well-Known Member
HBA Supporter
Joined
Oct 7, 2013
Messages
13,129
Location
97FL, Florida, USA
Would I be correct in saying that, most of the parameters( stall speed, level cruise speed, empty weight, gross weight) for an EAB are calculated at the end of the build and during the 40hr test flying?Wouldn’t it be at this point that you would determine say the stall speed and then you would know whether it meets the 45kn LSA criteria?
Calculations of those parameters should be part of the design process. For conventional designs, the predictions should be reasonably close, but actual parameters are proven in testing.

Would note that the very successful Vans RV-12 prototype did not meet LSA parameters (stall speed) and needed slightly more wing area.


BJC
 

stanislavz

Well-Known Member
HBA Supporter
Joined
Aug 21, 2016
Messages
952
Location
Lt
Could some-one clarify me on Szaraz Daphne ? If it have wings from this : Stits SA-7 Sky-Coupe

But fuselage from TW - it weights more, but fligths faster and stalls at lower speed.

Sky coupe

1614704331173.png

1614704373922.png
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
14,750
Location
Memphis, TN
A nose gear added to a Tailwind will eat about 7 kts off the speed. Tri gear to conventional is not apples to apples. I Ibet the Daphne is probably a hair cleaner anyway. Weights always tend to be better claims than accurate.

With any Wiki spec there has to be a tolerance of whoever put the spec in put all the spec in. Without someone’s real WB and measured speeds to a specific example, it’s all ballpark. You have to push two planes with the same engines across the same set of scales, with the same instruments and accessories to be pound for pound, mph to mph.
 

stanislavz

Well-Known Member
HBA Supporter
Joined
Aug 21, 2016
Messages
952
Location
Lt
A nose gear added to a Tailwind will eat about 7 kts off the speed. Tri gear to conventional is not apples to apples. I Ibet the Daphne is probably a hair cleaner anyway. Weights always tend to be better claims than accurate.

With any Wiki spec there has to be a tolerance of whoever put the spec in put all the spec in. Without someone’s real WB and measured speeds to a specific example, it’s all ballpark. You have to push two planes with the same engines across the same set of scales, with the same instruments and accessories to be pound for pound, mph to mph.
I know. So was my question - you have heavier airplane by more than a margin, more wing area, similar hp, but it top/cruise is faster. Ok, possible due to cleaner shape. But stall is much lower this one is illogical then..

You need more lift / tip vortexes to sustain your heavier airplane in air at same speed.
 

Pops

Well-Known Member
HBA Supporter
Log Member
Joined
Jan 1, 2013
Messages
9,159
Location
USA.
LSA sort of Tailwind looking, tri-gear, single place for up to a 300 lb pilot with full fuel, 112 sq' of wing area , 2414 airfoil, 28' 6" wing span, 680 lbs EW, 1100 GW = JMR Special.
 
Top