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Dec 30, 2011, 01:18 AM
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On my non F5B models I use ramp brake of about 0.3 sec(I think that is fast brake). If you have a fairly powerful setup(not F5B) and fly it more as a thermal model 1.0sec startup ramps gives good transition from thermal speed to climbing speed.
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Dec 30, 2011, 02:33 AM
Full Scale Piper Cub Driver
Piper J3's Avatar
Originally Posted by Lenny970 View Post

There's plenty of things that I know nothing about!

Wife gave me tee shirt for Christmas w/ lettering "Let's just say I'm right - it'll save time". My reputation precedes me.
Dec 30, 2011, 03:17 PM
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Lenny970's Avatar
I think I've built 3 or 4 Orions for others now, and I decided I'd add one to my own hangar.

Test flew it this morning and it flies very well! The compact size is handier to pull out for a few flights than a bigger 3-4 meter model.
Moves around very nicely, but also signals lift really well. Even in the weak winter conditions today, I had no trouble working several light thermals.

I started with the CG at 95mm, which I found way too noseheavy for my taste.
After a few adjustments, I settled on 104mm, which is very slightly positive (nose slooooowly pulls up in a dive test).

Flaps are very effective and she lands easily.
This would be a great model for flying from a confined field. She's a keeper!

Dec 30, 2011, 08:09 PM
Closed Account
I was able to get to flights in today finally without a motor mount failure. The soft brake worked well I think. With that and a light file on the blade mounts they folded up nicely not long after turning off the motor.

Besides the obvious, one of the coolest things about flying a plane like this is the sound it makes screaming around the sky. Plane moves out really well on 3s.
Dec 31, 2011, 08:34 AM
Registered User
Lenny, did we set mine up for 95mm? Mine seems a bit nose heavy as well.....I can move the 3s back, the 4s cant go back any further as it hits the spar.

What motor and cell count are you running?

Dec 31, 2011, 09:31 AM
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Lenny970's Avatar
Originally Posted by hidaven View Post
Lenny, did we set mine up for 95mm? Mine seems a bit nose heavy as well.....I can move the 3s back, the 4s cant go back any further as it hits the spar.

What motor and cell count are you running?

Yes, your's was at 95mm too. That was the best info I had until now.

You can add some tailweight inside the rudder hinge if you want. I needed about 3/4 of lead.

I just set it up for now with a 1506/1.5D/6.7 motor I had handy. Does a little over 1000 watts on 3S. I'll replace it with a 1506/2.5D/6.7 on 4S soon though.

Jan 07, 2012, 07:49 PM
Registered User
Hi Lenny,

I've really enjoyed this thread and all the high praise that seems to go along side this aircraft. I've been flying a foam Multiplex Easy Glider Pro with about 750 watts and want to move up to the next level.

I was wondering how the Backfire F5F and this model stack up in terms of battery options, airspeed range and thermal ability when light. I fly in predominantly windy conditions, 10-25 mph, and would like something that can rip up to altitude and then relax for a while yet land in smaller places. Can the Backfire be flown "tuned" down or do I need a zillion watts to properly power it?

Could I start off slow with the Orion in terms of prop and cell count and then add a cell and a more aggressive prop to get things moving. I like the idea of the throttle on a stick until I learn the switch and was even wondering if the Orion had enough room to fit a "starter" HV setup and move up in cell count from then. The Backfire looks great and I don't mind the additional cost as long as it can be flown on a very tame setup at first.

Thanks in advance for your time!

Best Regards,


The N
Jan 07, 2012, 11:47 PM
Registered User
Lenny970's Avatar

The Orion really isn't a fast glider. It comes from a thermal pedigree, and that is it's strong point. Yes, with the right power setup it can climb very fast, thermal quite well, and can land in a small area.
A Backfire should be faster, but won't thermal as well. It would probably not land as easily as the Orion either.

Just about any model can be flown on a lower cell count to start, then increase the power later with a battery change.

You might also consider a Spider. It's performance should be right between the Orion and Backfire.

You may want to give SUSA a call and discuss the options with Bob.

Good luck,
Jan 08, 2012, 10:22 AM
Registered User
Thanks Lenny,

I appreciate the comments.

Best Regards,

Jan 08, 2012, 10:37 AM
Registered User
Lenny, moved the CG back to 104. Night and day difference from the 95. Plane now sits there like a kite : )
Jan 08, 2012, 11:39 AM
Retirement is good

NAN Orion - A must have

Can I blame this forum for a “must have” on the NAN Orion? Sure, why not. Thanks guys!

I was flying a full house 2M Swift (circa mid 1990’s design) converted to electric with this setup: Neu 1105/2.5Y, 4.4:1 Maxon gearbox, RFM 13x9 narrow blade, Jeti Advance 40 Pro SB ESC, Sky 2200mah 3S 40c battery. AUW was 48 oz and the bird goes vertical to the limit of my lousy eyesight in 4 to 5 seconds. The motor/prop combo was as recommended by Bob at SoaringUSA and draws 39 amps (410 watts max measured static). Yep, that is right at the stated limit for the 1105 but for 5 to 10 seconds it has been a non-issue with zero noticeable heat increase.

So I did a “what if” with the Orion airframe at only 31 oz and immediately drove to SoaringUSA. Lucky guy, only a 30 minute drive! My numbers suggested I could build-out this bird for an AUW of 50 oz. giving a wing loading of only ~10.5 oz/sf while retaining the desired vertical climb performance. Remember that I was seeking LIGHT (not a hot-liner) as I am old, tired, sometimes grumpy and enjoy thermal flying.

I picked up the bird from Bob on the 3rd and did the maiden yesterday. Okay, so I am retired and can build at will. Wow! She weighs 50.5 oz, balances at ~105mm with no ballast, goes vertical as promised and thermals beautifully.

Just two quick (important) details, but can add more if there is an interest. The 3S battery and Jeti ESC fit side-by-side just behind the motor. This is a must to achieve a no-ballast configuration. The receiver is just behind the battery. Per Bob’s suggestion I used 4 MKS 6100 (not 6125) servos in the wing. All of this made for LIGHT!

As I generally fly aft center of gravities the ~105mm was not a great concern, but did a quick stability calc all the same. The numbers suggested a +5% static stability. In the real world the bird pulls up from a 45 degree dive with a solid but SLOW recovery… just what I like.

Enough! I am heading for the field…

Jan 08, 2012, 03:48 PM
Registered User
wow, im at 61 am i 10 oz heavier? I know my 1506 1.5d 6.7 is a little heavier. Im also running a 17x13 rfm and have a 850 LiFe RX pack. Are you ruuning a BEC?
Jan 08, 2012, 06:32 PM
Retirement is good

Weights (all in ounces):

Left Wing – 10.1, Right Wing – 10.0, Fuselage – 7.3, Stab – 1.7, Joiner – 1.2, Misc - ~1.0 for a total airframe of 31.3.

4 MKS DS6100 – 1.4, Hitec HS65MG (rudder) – 0.4, Hitec HS82MG (elevator) – 0.7 for a total of 2.5 for servos.

Neu 1105 and Maxon gearbox – 4.7, 2200 3S battery – 6.7, Jeti ESC w/ wires – 1.7, AR9310 receiver w/ satellite – 0.7, Prop w/ spinner – 1.4 for a total of 15.2.

Extension wires, servo tray, glue and light skeg (own design) aft of wing totaled 1.5 for the AUW of 50.5. Let me note that I am near minimum for control power but mine is not a hot-liner nor do I fly hard acrobatics. I only need enough servo grunt for a vertical climb and thermal flying. Also, I use CA glue with baking soda fillets for all joints... have for a couple of decades or more dating back to the super light RO8. Epoxy is heavy… and slow!

Yes on the BEC. I know I’m tempting fate but with proper management of the Lipo batteries and careful selection of the ESC I have not YET had a failure (searching for a chunk of wood now to knock on). Were this a multi-thousand dollar open class ship perhaps I would do otherwise, BUT the added receiver battery is just one more system to manage.

Note that I am using the Jeti Advanced 40 Pro SB ESC. There is a reason… well two. It is a switching BEC offering 5 amps and comes with an arming switch. It is also very slim, needed in this application, and can be had for well under a hundred bucks. I have had nothing but solid reliability with Jeti products which sadly I can not say for other well known ESC products that I have tried.

I hope this answers your question.

Best regards,

Jan 08, 2012, 11:20 PM
Closed Account
"As I generally fly aft center of gravities the ~105mm was not a great concern, but did a quick stability calc all the same. The numbers suggested a +5% static stability. In the real world the bird pulls up from a 45 degree dive with a solid but SLOW recovery…"

What exactly does +5% static stability mean? Sounds like I need to push my cg back some. I'm not sure exactly how I will do that though. Maybe I can swap the rf for the rx battery pack.
Jan 09, 2012, 08:11 AM
Retirement is good

Nice job on your Orion. Before moving stuff around in the airframe may I suggest you tape small flat lead sheets to the fin. Move the CG back in small increments until you find YOUR sweet spot. Some folks dislike aft CG’s, while others do. Once pleased you can glue a piece of lead to the fin post as Lenny suggested (brilliant, I thought). If only ¾ oz the airplane really won’t know much difference in the 0.15 oz/sf wing loading increase.

Another option may be using a 65C 1800mah 3S pack which should save about 1.2 oz in total weight, not a bad thing perhaps. Bob at SoaringUSA may offer an opinion on that capacity with the 1110/1Y you are running. If you like the sound (as stated) of the bird screaming around the sky at WOT like a hot-liner you won’t like the reduced capacity. You may want to check on heating without ventilation as well.

To your question: What exactly does +5% static stability mean? It means the CG of the model is 5% of the Mean Aerodynamic Chord (MAC) length ahead of the model’s Neutral Point (NP). Say the NP of the model is at 3.5” measured along the MAC, and the MAC is 8” long, then the 5% Static Margin point is 0.4” (5% of 8) ahead of the NP (at 3.1”). All of this is measured at and along the MAC which is somewhere around halfway out on the semi-span, NOT at the root of the wing. When we say the CG works okay at 105mm back from the wing root Leading Edge (LE) we are NOT saying that is 105mm from the LE of the MAC.

Notwithstanding detailed aero analysis and intense calculations the real world experience may differ from your expectations. If the sailplane is “twitchy”, hard to fly smoothly, tucks in a dive test, etc. move the CG forward! A dear friend and expert glider designer, Blaine Rawdon, likes the CG around 25% MAC. I generally like 38% to 40% MAC given fairly normal tail sizes like the Orion. What works best is what works best for YOU.

Calculating the MAC of planforms (wing, horizontal stab, vertical stab), moment arms, Neutral Points, Tail Volumes, etc. is tedious at best. All of this stuff is required for an aero analysis and I quit the hand methods a very long time ago. Let me put you on a wonderful site containing spreadsheets compiled by a super human being by the name of Curtis Suter. Under “Files” you will find a free download for glider designs with a cruciform tail. Fill-in the yellow cells and the spreadsheet will spit out more data than most human beings will ever need. Just note that one cell on the balance calc sheet requires you to enter “Stabilizer Efficiency.” This is a total WAG and makes a sizable difference in the static margin calc. I use 0.6 to be a bit conservative.

The site is at

BTW, Curtis gladly accepts donations.

Happy flying,


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