My idea would be to use a F5J fuselage (eg. Shadow2) with the vertical tail, but have wooden wings and a wooden horizontal tail. Easy to step up to real F5J.

Originally Posted by CloudSniffer

I like it a lot, anything to drive lower cost and the challenge of nice lite new designs. Bungee launch would also be very appealing. With that said I have drawn a 3m wing similar to the Yellow Jacket. Until I saw this though I was seriously considering a 3.5m instead for current F5J. I acquired a CLM Pro fuse just a couple days ago to design around. They are reasonably priced and pretty nice. So now to decide on the span for sure. My plan is to make wing and tail kits and use CF tube spars, open structure including cf tubes in the tailset. I fly with RevIain in our club and he is the CLM Pro dealer in the US. I can work something out with him so I can package the whole thing to save shipping since he lives 30 minutes away. Any feedback would be good at this point. It's a ways out but I am getting ready to head down the path.

Count me in as a flight tester if you kit your 3M/CLM design.

Our F5J BAM contest (August 25, 26) in New Mexico this year will have separate trophies for Three Meter Sailplanes made of wood or foam. It is not a separate class in the sense that there will be separate launch groups, everyone will still launch , fly and be scored together, but at the end of the contest those flying "lesser" sailplanes will be recognized for their performance. The contest will be held at the Balloon Fiesta Park which is a fantastic contest site with hotels and great restaurants minutes from the park and nice activities for family members.

Mike

What makes the difference in performance ?

1) the span.
2) the profile respect.

A 3m plane is 10cm/s less performant in sinking than a 4m one.
A 2m one is 20cm/s less.

Then a bagged plane or a sheeted wing on foam or a carbon sheeted D box wing will also have up to 10cm/s less sink than a classsic balsa ribs wing plus balsa sheet on it.

How many persons can make a foam + balsa sheet wing? Very, very few. They will have to buy it... Once again, you will have plug and play planes that will be the only planes in competitions...
So this entry class will have to be attractive for builders. Don't forget that youngs do not know how to build and how to repair. And the parents of the youngs we have don't know how to repair either...
Building its own plane (in a very easy way) is the only way for a young to know how to repair. It is also a very good factor to have very motivated competitors (you are very proud of your own plane you constructed!). You will then continue to fly over years (with more probabilities).

Then in order to have youngs and new pilots that enter into the competitions' matters, we must propose sometnink that is very cheap.
One question: What is the amount that a family can put on the table in september in order that their young son or daughter start to fly? This is exactly what may be proposed as an entry class.

In France, this represents something about 200 to maximum 300 euro if you include "christmast" gifts.


If we propose something more expensive, then we will fail.

The 3m class, is potentially the very maximum we can propose. A 2.5m span will be more easily done in the budget and assembled in 1 "school" year. And it is also with more performance than a 2m one.

On top of that, the capability to restart the engine is not a good solution at all. It pushes the competitor to take more risks, to go further, too far away from what he/she knows, so far away that he/she will surely make errors that will put the plane in an unsafe situation, even if (and also because of) the engine is restarted. This is absolutly an unsafe proposal and a very risky solution for a young competitor.

Marc

I am also a fan of 2.5 meters, but there are nice kits out there that are closer to 3 meters such as the Introduction and the Inside that are inexpensive and relatively easy to build.

I also agree that the restart rule is not necessary for the reason you have mentioned, but that is the rule in the USA.

Mike

Originally Posted by marc.pujol

What makes the difference in performance ?

1) the span.
2) the profile respect.

A 3m plane is 10cm/s less performant in sinking than a 4m one.
A 2m one is 20cm/s less.

Then a bagged plane or a sheeted wing on foam or a carbon sheeted D box wing will also have up to 10cm/s less sink than a classsic balsa ribs wing plus balsa sheet on it.

How many persons can make a foam + balsa sheet wing? Very, very few. They will have to buy it... Once again, you will have plug and play planes that will be the only planes in competitions...
So this entry class will have to be attractive for builders. Don't forget that youngs do not know how to build and how to repair. And the parents of the youngs we have don't know how to repair either...
Building its own plane (in a very easy way) is the only way for a young to know how to repair. It is also a very good factor to have very motivated competitors (you are very proud of your own plane you constructed!). You will then continue to fly over years (with more probabilities).

Then in order to have youngs and new pilots that enter into the competitions' matters, we must propose sometnink that is very cheap.
One question: What is the amount that a family can put on the table in september in order that their young son or daughter start to fly? This is exactly what may be proposed as an entry class.

In France, this represents something about 200 to maximum 300 euro if you include "christmast" gifts.


If we propose something more expensive, then we will fail.

The 3m class, is potentially the very maximum we can propose. A 2.5m span will be more easily done in the budget and assembled in 1 "school" year. And it is also with more performance than a 2m one.

On top of that, the capability to restart the engine is not a good solution at all. It pushes the competitor to take more risks, to go further, too far away from what he/she knows, so far away that he/she will surely make errors that will put the plane in an unsafe situation, even if (and also because of) the engine is restarted. This is absolutly an unsafe proposal and a very risky solution for a young competitor.

Marc

Corkey

IWhat would be wrong with a Bubble Dancer with Flaps, and Aileron? I.E a grown up THawk, with a CLM Pod and boom.

Love your work

John

@jbitz

BD's airfoils are designed for R.E.S. use.

You could try Supra's or Aegea's foils which are designed for the intended use.

Originally Posted by Stratigio

@jbitz

BD's airfoils are designed for R.E.S. use.

You could try Supra's or Aegea's foils which are designed for the intended use.

Lots of folks have done homebrew FH with AG3x foils. While intended for RES use, they perform reasonably well flapped.

Originally Posted by mawz

Lots of folks have done homebrew FH with AG3x foils. While intended for RES use, they perform reasonably well flapped.

The AG35 blend of airfoils are really very good as designed , and according to XFoil there are modest gains with postive and negative flap values. I am nearly finished with a full house 2.5 meter F5J using AG35-38, so we shall see if this is correct.

Mike

On 3m to 4m sink comparison I assume that's if they weigh the same. What if the 3m weighs 30 oz and the 4m weighs 50 oz. Flying F5J there will be a learning curve setting up for more wind and penetration. I am really intrigued to see what can be accomplished. I don't expect a light wood 3m to perform as good as a high end Moldie, but I do think with practice and knowing how to set one up you could do fairly well. Typically the 2m planes are in the bottom half of results so if you creep into the top half that would be good.

Bring your new 3 meter to Albuquerque for the BAM in August?

I think a good pilot can do much better than just the top half with a Woody.

Mike

Originally Posted by CloudSniffer

On 3m to 4m sink comparison I assume that's if they weigh the same. What if the 3m weighs 30 oz and the 4m weighs 50 oz. Flying F5J there will be a learning curve setting up for more wind and penetration. I am really intrigued to see what can be accomplished. I don't expect a light wood 3m to perform as good as a high end Moldie, but I do think with practice and knowing how to set one up you could do fairly well. Typically the 2m planes are in the bottom half of results so if you creep into the top half that would be good.

Originally Posted by MikeC

Bring your new 3 meter to Albuquerque for the BAM in August?

I think a good pilot can do much better than just the top half with a Woody.

Mike

IIRC the guy who won the Australia F5J championship last fall was flying a wood wing.

Originally Posted by mawz

IIRC the guy who won the Australia F5J championship last fall was flying a wood wing.

Yes, an excellent pilot, with those old outdated flat bottom AG airfoils.

Mike

Originally Posted by MikeC

Bring your new 3 meter to Albuquerque for the BAM in August?

I think a good pilot can do much better than just the top half with a Woody.

Mike

There is high probability of me bringing it to BAM. I flew a THawk in it last year.

John, yep we need flaps for F5J to nail those landings as good as we can.

Now, I just need a good pilot!!!

Finally have flown my 2.5 meter F5J glider and can say that using camber there is a very nice groove in thermal mode that is not there with the wing in the neutral setting. In very weak lift though I think the neutral setting is better. Still experimenting...

The AG3X airfoil really are very nice-even with flaps.

Mike