Gliders > Slope Soaring
Kostez
Brian:
Hi Fred,
I think that this is more a 'Dark art' than a science. :shock:
There is also a 'style' aspect to the Brittany type I think.
I don't like the knife edge performance unless there is huge lift.
Thank you for your input.
We should keep this going a bit to help develop 'our' understanding.
Brian
Fred:
Ah no, I leave the expert doing it on other forums :P
Brian:
--- Quote from: "Fred" ---Hi Brian,
Not to sure how to translate that, but that would be the fuselage moment (by itself), basically where in the fuselage the most lift is generated. not to be compared with were the stability is most generated (usually at the CofG of course)
Position is critical if you want a glider that perform well on knife edge (without much, or in theory without rudder input), and is about 15 to 25% from fuselage nose (just look at all the proper vtpr glider fuselages), the tail of the fuselage generating almost no lift (your fuselage tail can be a stick, that will not change much the knife edge performances)
Then, you need to select a good profile that will work at the correct Re number you are looking for, but most specificly for VTPR, a profile that will work well in no air speed (able to do a roll with no airspeed for exemple). You can have a look at the TP series, and of course, the good old SBs. All these profiles work with a certain size of ailerons etc etc
Anyway, all that is only computer theory, you will never match the speadsheets performances of a profile etc with a build, even Boeing don't pretend that, but the goal is to get as close as possible to the "perfect" recipient. As Dassault says, if it looks good, it will fly right! :D
On another note, I think lots of experts are talking about VTPR gliders lately (seems to have been discovered only a year or two ago...) but most, if not all the gliders they choose, compare etc, are barely VTPR gliders in the true sense of the term.
But they are great aerobatic machines. VTPR is another league, another way of flying altogether. I flew / tested tons of aerobatic gliders, but flying a glider truly designed for VTPR, is totally a different world by just the way the machine fly and react to your inputs.
Almost all aerobatic gliders can do a roll at wingspan altitude from the slope... But a handfull will do it at zero speed! I think this is the simpliest way to describe these machines.
--- End quote ---
Hi Fred,
Yes I think I understand.
In the first paragraph you are talking about fuz,, side area and side area distribution.
This is where they don't work for me.
In knife edge the fuz is the wing.
The CG should be at 30%ish, of the fuz side area.
The fuz should have a wing profile .
It should have enough side area to 'fly' in knife edge.
This side area should be effective at creating lift.
Wing profile - I agree and add that to be able to adjust camber ia good ! - 4 axis control.
For this the aileron/flap should be 30% of cord !?.
I also agree with 'a lot experts talk about VTPR gliders lately' .
I think it is a good time to try for something new - a little bit different.
I will try anyway.
Brian
JohnPearson:
Guys
I take an idea, draw a rough plan, then build a prototype model! Test fly the glider, THEN start to make changes. Yes Fred you are right, the old saying (if it looks right, it will fly right).
I have flown many types of gliders over the years, and have
noted some good design ideas and some bad. Would it not be simple to take the good design ideas and build a great model, because if you look at the designs of most of the gliders on the market ( they look over all, the same in basic design, except for size and aerofoil section).
NASA still use models to test design ideas, so lets get building :lol:
rasemote:
--- Quote from: "Brian" ---Hi Fred,
I am just trying to explore this subject a little bit more - for me and for other pilots that have an interest.
By static moment do you mean tail plane position relative to wing cord - ie; tail moment ??. If so do they have longer than normal or shorter than normal gliders.
So the Kostez at 60g/dm\2 plus is 'outside' the normal wing loading for VTPR. I know it is big and that weight does not scale up pro-rata with size.
Brian
--- End quote ---
hello
My fuselage at the exit of the mould made 1500 gr
for simple fact my kostez for the first flight(theft) made 7.5 for 4M
(more the glider is heavy more it is fragile)
emplanture 480 mm salmon 300
Stab emplanture 300 salmon 190
The principle of the kostez is its key of wing and its central girder if it is to respect your serat glider at the level of your piloting to see the Magazine MRA thierry
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