Interesting aircraft design – LH10

This plane has some of the elements I have been thinking of an efficient aircraft to have:

http://www.lhaviation.com/site_frame/bases_marges/index.htm

Specs promise 200 kts with 100 hp. Lets see. The plane has already flown, but not yet tests that determine top speed.

According to my calculations, providing they are right, this is not that much out of place. This plane in fact, is pretty much like a two place Vmax Probe. If the airflow stays laminar in the fuselage and wings, the 200 kts might be doable. The relation of stall speed and top speed of the 3.77 projected for this plane is a reachable value. Very interesting to see how it performs and if it does not go 200 kts, why. According to what I have read and would estimate, the drag coefficient of the LH10 should be very small unless there is something wrong that causes the airflow to separate.

The view from the LH10 seems to be as spectacular than from a glider. Would be excellent aircraft for flying for fun.

The airfoil used on this aircraft is particularly interesting. Reasons:
– E.g. NLF414F produces very low drag and very high glide ratio, but not without restrictions – the area of usable Reynold’s number is limited which limits the chord of the wing to a rather long one, and the wings of the LH10 would already be below that limit. They say that it is a wind turbine airfoil. I haven’t tried simulating the wind turbine airfoils yet, it has not occurred to me that they could be actually be useful on aircraft. However, this seems to prove that this was wrong assumption, and they are in the UIUC database for a reason. Lots of airfoils to investigate…

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    • ant1ant1
    • September 5th, 2008

    Hello I am also following this one too. Very sexy plane. I have met one of the engineers at an aircraft design course some weeks ago. The LH10 Ellipse was a good opportunity to test my newly acquired design skills!

    I cannot comment on the airfoils, but I have a few questions about the fuselage and architecture:

    The propeller is mounted on a separate shaft. I hope they got this one right (torsional problems) as there are many reasons why such a design can fail in flight.

    The propeller’s efficiency is likely to be affected by the placement of the horizontal and vertical stab. The prop is operating in turbulent air, and especially so at TKOF. How much efficiency loss I dont know…

    The propeller has to be rather small in diameter, efficiency?

    The whole tail is not “blown”. How much control is left at near stall speed?

    The lower part of the tail seems to be too agressively swept upwards (just an impression from the pics) this could cause pressure drag and further turbulence for the poor propeller.

    But still, what a plane, and what a project. Hat off!

    Ant1

    • karoliinasalminen
    • September 6th, 2008

    Hello,

    Thanks for your comment! At least someone reads this topic then…

    You are right, the propeller efficiency is most likely negatively affected by the nearby objects. Also the propeller shaft can be problematic. However, these shafts usually use flexidyne coupling and these have been used for years in many aircraft without problems. Without the soft coupling, there would be problems with the shaft. I don’t know what kind of coupling is in the Ellipse, but some kind there would need to be for the shaft be reliable.

    You don’t need to have a blown tail to have enough control near stall speed if you make the tail large enough. There are many aircraft which do not have blown tail, and they still have excellent handling qualities, near stall speed and otherwise.

    Small diameter prop affects negatively for the propeller efficiency. This depends also at which speed the aircraft is flying, the efficiency loss is higher at low speeds.

    Anyway, thanks for your great and informed comment, I hope I see your comments also in other posts in my blog!

    • ant1ant1
    • October 9th, 2008

    Hi Karoliina

    Believe it or not, I have LOST this blog and didnt know how to get back here (Google didn’t find it, found your old one!). It was by clicking on my own weblog (which I opened as a consequence of reading yours and wanting to comment) that I found this path again!

    (Now you can guess i’m not IFR-certified!)

    Thank you for taking the time to answer my comment. In the meantime I have discovered that the LH10 looks very similar to the BD-5 from Bede. Hmmm…. check it out!

    I have read more of your blog and like it very much. Have not yet had time to explore your music pages, but I will do ( I play the guitar when I’m not flying).

    I’m currently working on a 3D mockup of my dream plane. I have posted that plane’s target specifications in my blog (dont laugh, it’s the only post so far!). Would appreciate your comments. I’m doing the 3D in Blender and will oad it in X-Plane to test fly it….
    In the meantime I have flown the MCR 4S with an instructor and soloed on it. It is a great plane I think, but it falls short in the “comfort” and “passive safety” areas.
    Have a nice day. I hope Finland is not too cold these days. I remember my only night in Helsinki, it was great fun and freaking cold!

    Ant1

    • karoliinasalminen
    • October 9th, 2008

    LH-10 resembles BD-5, but it is longer than BD-5 (for example because it is dual seat plane and BD-5 is a single-seater) and has quite different wing design.

    Can you give me the link to your blog, I would like to see it.

    Can you tell me more about MCR 4S? I would like to hear your insight.

    In fact, it is currently too cold (and rainy) in Finland (I have got used to the Californian sun during the visits there). Uh…

    • PGRDAERO
    • February 12th, 2009

    The LH10 will need 200 hp minimum to fly 200 kts…
    In addition, what about the safety and reability of the shaft…for how many hours…ouchhh
    you need to study history before doing calculations…
    Just compare aircrafts perfs and specs, your judgment will be more realistic…
    havagood and safety flights
    Pierre

    • PGRDAERO
    • February 12th, 2009

    The LH10 will need 200 hp minimum to fly 200 kts…
    In addition, what about the safety and reability of the shaft…for how many hours…ouchhh
    you need to study history before doing calculations…
    Just compare aircrafts perfs and specs, your judgment will be more realistic…
    havagood and safety flights
    Pierre

    • PGRDAERO
    • February 12th, 2009

    The LH10 will need 200 hp minimum to fly 200 kts…
    In addition, what about the safety and reability of the shaft…for how many hours…ouchhh
    you need to study history before doing calculations…
    Just compare aircrafts perfs and specs, your judgment will be more realistic…
    havagood and safety flights
    Pierre

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