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Jul 11, 2010, 01:43 AM
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Jurgen Heilig's Avatar
Quote:
Originally Posted by hobie14
However you describe it I've always thought the climb rate of the Xeno is excellent and a real benefit of the design ...
If you come from a ZAGI with Speed 400 and Günther prop, you might consider the climb rate excellent. If you come from the FunJet, you may consider it rather poor. That's why it helps to have some figures.

Jürgen
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Jul 11, 2010, 07:06 AM
Where did Steve go ?
The most efficient airframe is one that has all its control surfaces in a neutral position. As soon as they enter the airflow you create drag as well as a lot of other things.
Drag reduces speed requiring more power to keep the same speed. Thankfully this really isn't an issue on the Xeno as it's got plenty of power to overcome the drag caused by using down elevator to control the want to climb under power.
This is best seen on DS models and Pylon racers.
A well designed and trimmed model/real plane will have the correct offset built into the firewall and angle of incidence built into the wings and tailplane to allow the most efficient travel under cruise conditions.



Quote:
Originally Posted by Jurgen Heilig
Lost efficiency? It doesn't matter whether you mix in a bit of down elevator with the throttle to reduce the climb angle or redcuce it manually with your elevator stick.

Jürgen
Jul 11, 2010, 08:50 AM
Registered User
Jurgen Heilig's Avatar
Quote:
Originally Posted by flyingrally
The most efficient airframe is one that has all its control surfaces in a neutral position.
...
A well designed and trimmed model/real plane will have the correct offset built into the firewall and angle of incidence built into the wings and tailplane to allow the most efficient travel under cruise conditions.
What I am pointing out is, that it doesn't matter whether you use a mix or your stick to control the climb angle - the end result is the same.

Raising flaps to reduce the airfoil camber will give you better penetration. How is that for efficiency?

You can't always correct the effects of your drive by side- or downthrust, especially when it is very powerful.

Jürgen
Jul 11, 2010, 09:21 AM
Where did Steve go ?
Quote:
Originally Posted by Jurgen Heilig
Raising flaps to reduce the airfoil camber will give you better penetration. How is that for efficiency?
Jürgen
The "natural" cruising position of any normal aircraft would be for flaps to be raised and therefore be in the most efficient position. Lowering flaps increases airfoil camber increases lift (depending on angle) increases drag and reduces efficiency.

Now as the Xeno has no flaps it's irrelevant to this thread.

Quote:
Originally Posted by Jurgen Heilig
You can't always correct the effects of your drive by side- or downthrust, especially when it is very powerful. Jürgen
True, however most firewall preset settings (as you would be well aware) are built to offset cruising constant torque not rapid angular acceleration moments of inertia. Which is why most pilots were trained on less powerful aircraft before being given the keys to things like Mustangs etc.

Thankfully the Xeno is highly unlikely to ever suffer from this and as there is no provision in the drive unit to make adjustments it's a mute point in this thread.


NNTR
Jul 11, 2010, 11:44 AM
Registered User
Jurgen Heilig's Avatar
Quote:
Originally Posted by flyingrally
The "natural" cruising position of any normal aircraft would be for flaps to be raised and therefore be in the most efficient position. Lowering flaps increases airfoil camber increases lift (depending on angle) increases drag and reduces efficiency.
...
Unfortunately the English language is a bit sloppy here. I was not referring to "Landeklappen" (landing flaps), but "Wölbklappen" (camber flaps).

Reducing the camber by raising those flaps increases the efficiency of a glider getting from A to B in a headwind; you get there faster und lose less height.

Jürgen
Jul 11, 2010, 04:39 PM
Registered User
hobie14's Avatar
Quote:
Originally Posted by Jurgen Heilig
If you come from a ZAGI with Speed 400 and Günther prop, you might consider the climb rate excellent. If you come from the FunJet, you may consider it rather poor. That's why it helps to have some figures.

Jürgen
Dear $$$$$ ..... give me strength ......
Jul 12, 2010, 06:40 AM
Registered User
Quote:
Originally Posted by 2500GENE
To the average American RC pilot, those terms "glides forever" and "bat out of hell" describe a planes performance better then stating wing load or grams thrust. We have trashed the English language to the point where learning our slang is as important as learning proper English to be able to communicate properly. I'm always amazed by Europeans who learned English as a second language and post on these threads so well when half the people in this country can't type a legible post.
Jurgen, I enjoy reading your post and reviews. Keep up the good work.

Gene
Very well said.
Especially true since the German language is much more precise than English and MS Office was invented in this country - F7 is literally unknown...

BoKo
Jul 13, 2010, 01:23 PM
More Motors, More Fun... :-)
nioa's Avatar

Xeno'd


Just got my new xeno last night. It's a nice plane. The Elapor foam is much nicer than I expected. Very smooth.

Question: Will hot glue bond well to Elapor?

I build with EPP, and I love it. I always try to use hot glue since it bonds so well. If I can make repairs to Elapor with hot glue that would be great. Also, does hot glue bond well to the regular plastic parts?

I was a bit surprised to see that the shaft used to connect the motor to the prop was hollow. I expected that a least the end that is grabbed by the collet would have a solid insert.

Would that be a good reinforcement, or is the stock set-up strong enough?

Thanks!
Jul 13, 2010, 01:58 PM
Registered User
I don`t know if you can use hotglue.
I used Zacki Elapor together with activator and believe me, It sticks like hell.
Much lighter also.

The metal shaft is strong enough. Have had about 12 flights or so without any problem with the shaft or engine.
If you make sure that the motor and propellor are aligned correctly you shouldn`t have any problem. Did you buy the standard or the tuning set?

Willem.
Jul 13, 2010, 02:39 PM
Registered User
Jurgen Heilig's Avatar
Quote:
Originally Posted by nioa
...
Question: Will hot glue bond well to Elapor?

...
Would that be a good reinforcement, or is the stock set-up strong enough?
...
You can use hot glue to fix servos in the wing, but I would not use it for structural joints. Not as strong as CA or PU glue and much heavier.

The steel tube is fine. As the collet apllies pressure from all sides, there is no risk to squash the tube. The steel tube is actually lighter than the previous carbon fibre shaft.

Jürgen
Jul 13, 2010, 02:54 PM
More Motors, More Fun... :-)
nioa's Avatar
Thanks to all for the info. I'm glad the tube is strong enough.

I'm going to build her tonight. I will be installing the servos on the top of the wing.

Now I just have to think about how I want to decorate the airframe. I don't care for the decals provided. I am thinking of using Microlite covering, but I will have to test that. Microlite sticks reasonably well to EPP, and will still come off for repairs, but the Elapor seems "greasier" so it may not adhere well.
Jul 13, 2010, 03:31 PM
Registered User
Jurgen Heilig's Avatar
Quote:
Originally Posted by nioa
...
I am thinking of using Microlite covering, but I will have to test that....
Why cover at all? The Elapor surface is much smoother than EPP and you can just simply paint it:

http://www.rc-network.de/forum/showp...&postcount=718

Jürgen
Jul 13, 2010, 04:15 PM
The desert collection
jpgcag's Avatar
Quote:
Originally Posted by nioa
Thanks to all for the info. I'm glad the tube is strong enough.

I'm going to build her tonight. I will be installing the servos on the top of the wing.
I've got the carbon fiber tube on mine and I've had no problem with the shaft and that is with a couple hard landings out in the desert. I sure wished I would have put my servos on top of the wing. I've already stripped one servo out because of having to land on sand and gravel. My Swift flying wing lost a servo too because of where I'm forced to fly. Now my Mini Slingers have no problem at all. Everything is on top!
Jack
Jul 13, 2010, 04:15 PM
More Motors, More Fun... :-)
nioa's Avatar
Jürgen, won't that paint be very heavy? The images you linked to look nice and rich. What kind of paint is that? I would be very interested in that kind of paint.

On EPP, I use markers, but that is kind of iffy, as you generally see the pen strokes, unless the marker is very wet, but that is because EPP is a sponge, so to speak. The surface of Elapor seems more "sealed". Anyone have experience with markers on Elapor?

As a side note, I sure wish I could buy slabs of Elapor for building, although it seems heavy, it seems to have alot of really good properties.

Nick
Jul 13, 2010, 04:35 PM
More Motors, More Fun... :-)
nioa's Avatar
Quote:
Originally Posted by jpgcag
......... sure wished I would have put my servos on top of the wing. I've already stripped one servo out because of having to land on sand and gravel. My Swift flying wing lost a servo too because of where I'm forced to fly. Now my Mini Slingers have no problem at all. Everything is on top!
Jack
I plan on using a very sharp razor inside of the servo bay to cut straight up through to the top of the wing, then push the cutout to the bottom of the wing and secure with medium CA. If I do a good enough job, then I should have a reasonably accurate servo mounting hole on the top. The servo wire can of course be run to the bottom of the wing using the intended channel on the wing bottom.

Great thing about foam is as long as your cuts are sharp and clean, patching up holes and making mods is not all that difficult.

Now that you have to repair that stripped servo, perhaps it would be a good time to move the servos upstairs.


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