RC Gliders, Sailplanes and Slope Soaring Discuss rc gliders,rc sailplanes and slope soaring in this forum. Thermaling techniques, airfoils, tips, etc

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Old 10-24-2002, 09:20 AM
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talybont
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Hi,

just for interest. Are there some guys with sailplanes over 5 m / 15 ft in this forum? In Germany this is nothing special but in Amerika it seems to be quite seldom.

CU,
Armin
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Old 10-24-2002, 09:52 AM
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Hi, Armin, I'm not in the 5m+ range either (yet), but have plans to do so.

However, I think, those guys are mostly at the HP of the ISSA
(International Scale Soaring Association ) :
ISSA , there also have a forum there

Michael
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Old 10-24-2002, 05:40 PM
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Hi Michael,

this is a very unclear forum. It takes too much time to find something interesting. RCUniverse is much better in this way. It reminds me to the german http://www.rc-network.de .

MfG,
Armin

Maybe there are some fans of big sailplanes. The picture below shows me and a 733 cm DG 100 with a Lehner 1940/16 and 32x RC 2400 inside (flap engine, I don't know the english word for german Klapptriebwerk).
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Old 10-24-2002, 06:23 PM
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Sorry, guys, but I'll answer Talybont in german :

Hallo, Armin, wir koennen auch deutsch reden (schreiben).
Mit Deinem Kommentar zu dem Forum bei der ISSA hast Du natuerlich recht, aber wie Du selbst schon sagtest, ist die Scale-Grossseglerfliegerei hier bei weitem nicht so gaengig wie in Deutschland.


Hier auf RCUniverse, gibt es nur ab und zu mal etwas dazu, bei RC Groups , gibt es ein Forum fuer Scale-Segelflug :Scale Sailplanes , da ist aber auch nicht allzu viel los. Deswegen treibe ich mich auch vielmehr auf dem Segelflugforum von RCN herum.

Ansonsten gibt es noch das Forum bei Sailplanes Unlimited , das ist aber genauso aufgebaut wie das der ISSA.

Wie gesagt, noch bin ich nicht in die 5m+ Klasse vorgestossen, soll aber naechstes Jahr vielleicht soweit sein, bis jetzt fliege ich eine ASH26 von Multiplex. Neben Deiner DG natuerlich schon fast ein Spielzeug

Klapptriebwerke werden hier "retractable power plants" genannt, meistens aber kuerzer und treffender : up & go

Gruss, Michael
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Old 10-24-2002, 07:43 PM
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Default Re: giant sailplanes

Quote:
Originally posted by talybont
Hi,

just for interest. Are there some guys with sailplanes over 5 m / 15 ft in this forum? In Germany this is nothing special but in Amerika it seems to be quite seldom.

CU,
Armin
Armin,

You're right ! Not only large sailplanes are quite rare here, but sailplane, generally speaking, are ignored. Most RC magazines never give news about sailplane world. It shows in the way most pilots fly. In france, and I guess in germany, a lot of pilots fly both, with a preference for either one, here it seems much more compartimented, most planes pilots have never flown a sailplane, and vice-versa. There is exceptions, obviously, but still, nothing close to what you see in Europe !

Bernard
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Old 10-25-2002, 05:46 AM
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Hi Michael,

danke für die sprachlichenTips .Up & go, habe ich schon einmal gehört, ist mir bloß nicht eingefallen. Was auch nicht so gaengig ist, dass jemand in den USA so vorzüglich Deutsch spricht :thumbup: .

So guys, back to international languages . Let's go on. I think you have to import most large sailplanes from Germany. Is it very expensive to buy a Multiplex ASH 26 in the US?


CU,
Armin
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Old 10-26-2002, 11:04 PM
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-vor funfzehn jahre habe Ich gelernt, seit zehn jahre habe nichts sprechen.

Did that make any sense whatsoever? I could understand the post from MTT, but only by reading each sentence twice.

Anyway - Here's a link to the 4m ASH 26 available from the US Multiplex dealer. http://www.multiplexrc.com/ash26.html

Does Multiplex make a larger version?

I just put the first flights on an old DG800M with the up & go. This one sat unused in a guy's shop for years. It's the 3.6 - 4.2m version from EMS. They don't seem to even make airplanes this "small" anymore. Uses a MEGA S7, 16x1400 Nicd, 11x6 Graupner prop. Anybody know who's "Klapptriebwerke" this could be? It's mostly metal, with some reinforced plastic pieces. I might need a new drive belt sometime.

The thrust line must be wrong, since the plane noses over and scrubs the ground when I give it throttle. The prop stands verticle when deployed. It probably ought to be tipped back 10-15 degrees.

Luckily, I had a friend fast enough to run along side and steady it until there was enough airspeed for the elevator to trim it and takeoff. Any other trim tips would be welcome.

I also fly a 2.4M Pilatus B-4. I recently saw a 5m pilatus for sale and almost jumped on it. Of course then I would need a tow plane & pilot. There is a club in Orlando where they do this - I need to visit those guys.

FWIW, I fly everything I can. I have a gas powered stinger in the air, would be a fine tow plane. Next off the bench will be a DF F-18.
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Old 10-27-2002, 02:04 AM
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Quote:
Originally posted by Johng
-vor funfzehn jahre habe Ich gelernt, seit zehn jahre habe nichts sprechen.

Did that make any sense whatsoever? I could understand the post from MTT, but only by reading each sentence twice.
Yes, it does: Translation:
"J'ai appris pendant 15 ans, cependant je n'ai pas parle depuis 10 ans" . OK, OK,
"I learnt for 15 years, I have not spoken since 10 years, though"

Quote:

Does Multiplex make a larger version?
Not to my knowledge.

Quote:

FWIW, I fly everything I can. I have a gas powered stinger in the air, would be a fine tow plane. Next off the bench will be a DF F-18.
Good for you. There is so many different kind of flights to experiment !

Bernard
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Old 10-27-2002, 02:27 AM
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No, Multiplex does not make a larger version of the 26, the biggest sailplane they make is the Condor , with 4.2 m span .

If you want abigger version of the 26, you would have to go to to Uwe Gewalt , Bruno Rihm , or to Reinhard Schueler , he has one with 4.8m, and one with 6m span.

That up&go on the DG800 sounds like one of the Graupner units.
Is it belt-driven, with the motor in the fuse, and the belt is tensed when the unit is extended ?

Quote:
The thrust line must be wrong, since the plane noses over and scrubs the ground when I give it throttle. The prop stands verticle when deployed. It probably ought to be tipped back 10-15 degrees.
That is a problem inherent to up@go power plants, since the propshaft ( and thus the thrustline) will always be at a certain distance from the C/L of the sailplane, and therefore generate a nose down moment, even if you tip it back.
The only way to overcome this, is to apply up elevator when advancing the throttle, either manually, or through a mixer.

Michael
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Old 10-27-2002, 04:27 AM
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I went to an event recently in the UK and found that mt 4m Astir was starting to look small. Check out the pictures on

http://web.ukonline.co.uk/sssrcsoaring/

Most of the glass ships flown are German but even the plan built models as designed by Chris Williams are getting huge. There is no doubt that the bigger the model the larger the smile.
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Old 10-27-2002, 04:31 AM
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Here is another picture from

http://web.ukonline.co.uk/sssrcsoaring/
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Old 10-27-2002, 10:20 AM
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Hi folks,

I think the up&go EMS uses is a Graupner or Elicker. Markus Elickers up&go's are perfectly scale (Binder system) but very expensive, too. And both have the same disadvantage: the motor remains in the plane and it has to drive a belt. Thermic problems are quite natural.
My father built an own up&go with motor outside and another special. The motor moves only 40 mm forward while going outside. This is realized by a kind of railway inside the plane.

I have got no problems while starting. I only need a friend at one wingtip for 3-5 meters to keep the tip out of gras. The originals do the same way.

MfG,
Armin
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Old 10-28-2002, 04:56 PM
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Quote:
That up&go on the DG800 sounds like one of the Graupner units.
Is it belt-driven, with the motor in the fuse, and the belt is tensed when the unit is extended ?
Yes, that's it. It has the 11x6 prop on it. I wonder if a 12x5 (Graupner) or 12x4 (APC) would give me better climb?

Quote:
That is a problem inherent to up@go power plants, since the propshaft ( and thus the thrustline) will always be at a certain distance from the C/L of the sailplane, and therefore generate a nose down moment, even if you tip it back. The only way to overcome this, is to apply up elevator when advancing the throttle, either manually, or through a mixer.
Hmm, I've seen mpg clips on-line of up&go launches, without the pitch tendency I see. Problem for me is, at zero airspeed, there's not enough elevator to compensate for the pitch down.

Do you find that prop-blast over a deflected elevator is enough to keep the tail down??

BTW- the reason for the tip-back on the prop, would be to increase the down-angle of the prop-blast on the stab and increase the self-trimming tendency. Unfortunately, I checked the possibility of doing this on my plane, and it isn't practical.

I suppose on pavement, the rolling resistance is less, and it would be easier to get the plane up. I believe for grass I will pursue 2 things- a takeoff dolly to keep the nose level and a bungee assist. The bungee assist will keep me from leaving valuable electrons in the grass anyway.

Any suggestions on the bungee assist? I intend on using the tubing from a heavy duty high-start and either a chin-mounted hook or tow-release. Since the motor is so easily removeable - I plan on flying from the tow at some point as well
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Old 10-28-2002, 07:27 PM
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John, I have no experience with up&go's, but I have done a lot of reading about them, because I want to install one in my Multiplex ASH26.
I already bought a Graupner unit for this, on eBay, but so far, I could not bring myself to cut open the fuse of the ASH.
Also I am not sure about the drive system, what motor, number of cells, etc.

I would like to hear more about your DG with the up&go, anfd your experiences with it.
Do you take off from the ground ?

Michael
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Old 10-29-2002, 08:48 PM
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John & Michael,
I fly an old EMS DG800S with the Graupner/Mega up and go. I use 16 cells and a Graupner 12 X 6 prop. I do not recommend this old system but it does have more than adequate power. I use a catapult to start; saves lots of energy and is painless. I use a "Y" bridle setup. The biggest problem is getting the prop stopped at the right position for the retraction. Compared to the new Elicker or Hoffman, this is an antique!
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Old 10-29-2002, 09:58 PM
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Good to hear from someone else with a similar setup. It would be interesting to know if you get better climb than I do with your prop choice. With the 11x6, I get ok climb -but only at full power. I get maybe 175-200m altitude after a 3 - 3.5 minute run. Do your Nicads get quite hot? Mine do. I am actually going to run an air tube from the nose port into the battery heat shrink.

Before I flew this unit, I had no problem with the prop-retraction. The bearing-spring-cam system seemed to work very well and dependably. However, on the second flight it did not center - - hung up outside the fuse, and has been a little tempermental since. It does not always turn to line up. I will be looking at the hub, and giving it a good lube as well. You would think the airflow on the prop would assist in turning it to the correct location. Gary, got any tips for this?

I have just installed a chin hook in order to do the bungee assist. We'll see how it works this weekend. I plan on just using my heavy duty high start.

Right now I have a 1400 Mah 16 cell pack, but would like to upgrade to something like a 2400 pack. But, that's alot of $$ for a pack! Recommendations on where to get a pack are welcome.

Mike: I was taking off from the ground, but with the mentioned problems. I believe the bungee launch will allow an assisted ROG that will save alot of headaches.

BTW - for the first few flights, we installed a Garmin E-trex Summit GPS unit with pressure altitude recording. That was cool. It recordered max height (around 600 ft) , max speed ( about 75 mph) and the whole ground track and total linear distance covered (2.5 mi.) Pretty cool toy:
http://www.facewest.co.uk/Products%2...rex-summit.htm
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Old 10-29-2002, 10:26 PM
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John,
My bird is showing her age and a few replacement parts might help but it is really an outdated system. Once you have flown the new systems you don't want to go back. In fact, I now rarely use the up and go; I tow her up. I'm using N-1700SCR's and they hold up very well. I get several climbs out of them. As for the battery temperature, I can't say as by the time I land everything has cooled off.

For the cat rubber I use a doubled 12mm surgical tube. It is 7.5 meters long after doubling and that is plenty of power. The "Y" birdle works very well. The hooks are about under the wing leading edge and about 1/3 up from the bottom to the wing. Highly recommended over a single hook!

I've had the prop hang up a couple of times and darn near tear the doors off on the retraction. Over time I have developed a method that works most of the time.

There are a couple of pictures on one of my sites at: http://www.retterbush.de/Flying/Flying_3/flying_3.html

Gary
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Old 10-29-2002, 10:43 PM
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Gary, what type of MEGA motor are you using, I wanted to run the numbers on Motocalc, but there are several Mega's listed.

Michael
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Old 10-30-2002, 12:03 AM
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I guess I really am getting old and forgetful! I just checked to see which Mega is in her and noted the prop is a 10.5 X 6 and not the 12 X 6. I should open my eyes before my mouth! I can't tell which motor it is as I can't see enough to read other than "Mega". I don't recall which motor it is. Sorry!
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Old 10-30-2002, 12:55 AM
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Mine's an S-7
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Old 10-30-2002, 01:07 AM
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Hey Gary:

My -800 has a fuselage the color of light butter or old cream. It definitely doesn't match the white covering on the wings. I don't know if it's just from age or what. How 'bout yours? Hard to tell in the pics.
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Old 10-30-2002, 01:17 AM
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Oh, yeah - about your power set-up, there is something going on here. Mine gives me about 3.5 minutes of run time, one shot. The climb rate isn't spectacular, but I'm not horsing the nose up either. I've been letting 'er fly. Probably 40 mph or so in climb.

Does this sound about right to you Gary?

I'm sure I've been wasting some energy doing the ROG bit, but not enough to explain a 3-1 difference in performance between me & Gary.

I guess I gotta go cycle this pack and see what charge it's holding.
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Old 10-30-2002, 08:32 AM
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John,

I'm fairly sure my motor is also an S-7 but would not bet on it. My gelcoat is slightly off white but apparently not like yours is. If I compare it to some of my other birds I notice it, otherwise no. On the run time; I have 1700's and they are pretty good ones. The cat start makes a BIG difference. That is probably worth a half a climb. I tend to favor 2 smaller climbs rather than one big climb. For one thing the batteries have a chance to cool a bit and to recover a little . As for run time, I've never really measured it. Maybe I'll check the static amps this afternoon. It could also be that you have better eyes than I do and my climbs are not as high!!

I bought my DG from Thomas Schmidt and it was one of the prototype planes for the EMS system. It is quite old and even has blade joiners for the wings. It has been around a bit! However, the batteries are new.

Gary
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Old 10-30-2002, 10:41 AM
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Hi Gary,

what do you think about RC 2400 to increace your performance?


CU,
Armin
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Old 10-30-2002, 04:01 PM
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Armin:

I was considering the Nicd upgrade myself. I just tested this 1400 pack and it is indeed getting the rated charge, although that doesn't really impress me.

Spent some time looking around for good prices online last night. Looks like it will be at least $90 for a nice pack.

I notice from the pic of your plane's interior, that you package your Nicads in bundles of 8 cells. I was considiering this for cooling purposes, as well as for convenince of locating the packs relative to the CG. With the one piece pack I have, it only fit well in one spot in the plane. Do solder all the leads together to make up one big pack, or do they all plug into a harness so they can be removed independently?

BTW - Can anybody tell me about the difference between Nicd SC, SCR, SCRC cells? I've seen SCRC cells a couple of places and those are really costly.

Also, I spent some time last night futzing wth the top end of the Graupner up-n-go to see where the sticky points are that keep it from retracting correctly - with the prop straight. Seems that the main culprit is the bearing on a spring-loaded slider that engages the prop hub to straighten it. Mine had gotten dirty and dusty and would stick about halfway up, without engaging the prop well enough to straighten it. I believe this trouble can be fixed by liberal doses of WD-40 at each flying session. Once I cleaned that up, it worked perfectly.

Michael, you may want to go ahead and pull yours apart and get to know the innards. Believe me, you will have to sooner or later anyway. One mod I made was to put a sleeve on the tensioning cable where it exits the main tube near the bottom. If you don't do this, the cable will wear thru in a relatively short time.

Also, if I was going to power this thing from scratch, I'd probably buy a brushless motor and ESC, instead of the S-7, as efficiency gains are on the order of 2x from what I hear.
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