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Jan 13, 2017, 01:20 PM
Flying R/C since 1964
kallend's Avatar
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Discussion

Resurrection


I'm thinking of resurrecting my old (not flown in 15 years) rocket gliders, Aerotech Phoenix and a Ladyhawk delta.

I'll need to update the radios from the old 72MHz stuff. I'm really interested in what batteries to use - in the past I used very small NiCd but I'd like to go to LiPos.

I already have the 2.4GHz Rx's that will run on 3.5 - 9V power.

So do I go 2S + BEC to run the old but still good servos, or bite the bullet and buy HV servos and run directly from the 2S pack?
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Jan 13, 2017, 07:38 PM
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A lot of us use single lipos and do just fine. I cannot say that 15 year old servos can operate well at 3.7v, that is something you would need to test.


Richard
Jan 14, 2017, 11:30 AM
Flying R/C since 1964
kallend's Avatar
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Quote:
Originally Posted by The Tellurian
A lot of us use single lipos and do just fine. I cannot say that 15 year old servos can operate well at 3.7v, that is something you would need to test.


Richard
So a modern Rx will operate OK on a 1S lipo? Didn't know that.
Jan 14, 2017, 04:52 PM
Registered User
Some do, some not so much. I use Frsky and they have no problem. You only need to check the Rxs' specs for a voltage range of 3.5v at the bottom end as below that the lipo is flat anyway. Also a larger cell and/or one with a greater C rating is better, because under load the volts can sag below the Rxs' limit and cause a brownout reset and with a larger C is less likely. Spectrum's early stuff was known for that from what I've read though the new ones have improved and Frsky almost never. Actually I think Frsky's reset was so fast no one noticed it. For example my Snagletooth delta RCRG using 2 d60 servos, runs on a 30C 400mah 1s which provides 400x30=12000ma or 12 amps power. More than enough.


Richard
Jan 17, 2017, 12:07 PM
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burkefj's Avatar
I'm currently running a single 25c 500mah eflite lipo directly to my AR-400 and 6000 series spektrum receivers with two hs-55 or 2 hs-65 mg or hb servos with no issues over many flights on a charge.....But my gliders and kits that I do are set up for about 60-70mph boost speed so not terribly fast and their flight times are around 2 minutes or so. I'm doing 6-10 flights in a session.

A pheonix probably has plenty of room to run a 2s and bec that model is larger and flies faster and so surface/servo loading can probably go higher and is probably a safter route if you aren't going to swap out servos,.

For the ladyhawk it depends on what servos you are using. I like the simplicity and cost savings of not having to run a bec. But in older designs they might require more nose weight anyway due to component placement and design for weight at the time, so you may not be hurt by a 2s and bec or a large 1s simply for balast....
Jan 17, 2017, 01:49 PM
Flying R/C since 1964
kallend's Avatar
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Quote:
Originally Posted by burkefj
I'm currently running a single 25c 500mah eflite lipo directly to my AR-400 and 6000 series spektrum receivers with two hs-55 or 2 hs-65 mg or hb servos with no issues over many flights on a charge.....But my gliders and kits that I do are set up for about 60-70mph boost speed so not terribly fast and their flight times are around 2 minutes or so. I'm doing 6-10 flights in a session.

A pheonix probably has plenty of room to run a 2s and bec that model is larger and flies faster and so surface/servo loading can probably go higher and is probably a safter route if you aren't going to swap out servos,.

For the ladyhawk it depends on what servos you are using. I like the simplicity and cost savings of not having to run a bec. But in older designs they might require more nose weight anyway due to component placement and design for weight at the time, so you may not be hurt by a 2s and bec or a large 1s simply for balast....
Yes, I've pretty much decided on 2S + BEC for the Phoenix.

Still thinking about the Ladyhawk (which I designed, incidentally). If I repeat the on-board ignition I'll want a higher voltage anyway.
Jan 17, 2017, 01:59 PM
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burkefj's Avatar
If you did onboard ignition I would have a separate small 2s or 3s battery for ignition anyway depending on your igniter/motor, I wouldn't want to run the firing ckt off of the same rx battery especially if it is small. Nice to see another rocket glider person hanging around.

Quote:
Originally Posted by kallend
Yes, I've pretty much decided on 2S + BEC for the Phoenix.

Still thinking about the Ladyhawk (which I designed, incidentally). If I repeat the on-board ignition I'll want a higher voltage anyway.
Jan 18, 2017, 12:04 PM
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kallend's Avatar
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The Phoenix restoration is coming along nicely. Radio system checks out OK, and very old monokote job has been refurbished.

Unfortunately I can't find the plans, and the manual (which I have) doesn't specify the CG position.

As I recall, this design is fairly tolerant of CG positioning, given its generous tail area, but if anyone knows where the design CG is, I'd appreciate knowing.

Thanks.
Jan 18, 2017, 05:10 PM
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burkefj's Avatar
I've been chatting with Bob Parks lately, I pinged him, will see what he says....I found the manuals online but not the plans.

Quote:
Originally Posted by kallend
The Phoenix restoration is coming along nicely. Radio system checks out OK, and very old monokote job has been refurbished.

Unfortunately I can't find the plans, and the manual (which I have) doesn't specify the CG position.

As I recall, this design is fairly tolerant of CG positioning, given its generous tail area, but if anyone knows where the design CG is, I'd appreciate knowing.

Thanks.
Jan 18, 2017, 05:57 PM
Registered User
Argh.. I went looking for the CG info and could not find it either! The problem is all the CAD drawings are now 25 years old, and nothing will open those formats anymore. I did export them to some newer, standard formats, but lost all the lettering and symbols!

But the rough answer is " on or a bit ahead of the wing bolt" I think that was liftoff CG. It's been a while! As you mention, with the big tail, it is pretty tolerant. The whole thing was designed to be pretty tolerant and easy to fly so it would survive that first test flight with a less than skilled pilot.

I do still have a couple of archived original kits, but they are REALLY hard to get at. It would take a couple hours to get to them in the storage area.

As for batteries and radio. I tend to be cautious about running 1S LiPoly on anything that was not specifically designed for it. So, with old servos in a Phoenix, I would do 2s with a BEC (just a small ESC with BEC would do fine). Its not worth scrimping on battery anyway, since you will just replace it with ballast to get the CG right. If you have to add metal to the nose for weight, add some electrolyte too!

BTW, I have been flying mine with 29mm motors, both reloads and single use. They are a slip fit into the 32mm casing. So, I just add a bit of tape for a snug press fit into the 32 then the same to get the 32mm casing into the plane.

My 1992 vintage Phoenix has carbon tube pushrods and a Hitec HS 85 on elevator (a bit more torque than typical for that size servo). I have regularly flown it with F50 single use and F52 reloads.

Bob
Jan 18, 2017, 08:44 PM
Flying R/C since 1964
kallend's Avatar
Thread OP
Quote:
Originally Posted by parky
Argh.. I went looking for the CG info and could not find it either! The problem is all the CAD drawings are now 25 years old, and nothing will open those formats anymore. I did export them to some newer, standard formats, but lost all the lettering and symbols!

But the rough answer is " on or a bit ahead of the wing bolt" I think that was liftoff CG. It's been a while! As you mention, with the big tail, it is pretty tolerant. The whole thing was designed to be pretty tolerant and easy to fly so it would survive that first test flight with a less than skilled pilot.

I do still have a couple of archived original kits, but they are REALLY hard to get at. It would take a couple hours to get to them in the storage area.

As for batteries and radio. I tend to be cautious about running 1S LiPoly on anything that was not specifically designed for it. So, with old servos in a Phoenix, I would do 2s with a BEC (just a small ESC with BEC would do fine). Its not worth scrimping on battery anyway, since you will just replace it with ballast to get the CG right. If you have to add metal to the nose for weight, add some electrolyte too!

BTW, I have been flying mine with 29mm motors, both reloads and single use. They are a slip fit into the 32mm casing. So, I just add a bit of tape for a snug press fit into the 32 then the same to get the 32mm casing into the plane.

My 1992 vintage Phoenix has carbon tube pushrods and a Hitec HS 85 on elevator (a bit more torque than typical for that size servo). I have regularly flown it with F50 single use and F52 reloads.

Bob
Hi Bob

We corresponded a lot some 25 years back. I had a pre-production kit that you sent me. I stopped flying it when BATFE had their conniption about APCP and now I've retired I decided to bring it back.

I moved three times since I built it, got divorced, remarried, widowed, and remarried again. The plans got mislaid somewhere along the way but the plane survived it all unscathed.

I decided to run 2S and find I can have a pretty big pack up front now. My S133 servos seem to be in good shape still. I programmed spoilerons.

It must move out pretty quickly on a F52!

Weren't you in Massachusetts back when?

http://mypages.iit.edu/~kallend/phoenix9.jpg
Jan 20, 2017, 05:08 PM
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burkefj's Avatar
John, there was a thread recently on rocketryforum that mentioned the ladyhawk design claiming that when RCM did the plans they changed a few things and made it almost unflyable, several people claim they never saw one fly right when built from the plans. Do you know anything about this, what was done wrong if there was, was it cg location or ? It appears to be a fairly simple delta and the cg location doesn't seem unreasonable at least on the picture I saw.

This was the quote...

by Greg Smi Wed, 14 Aug 1996 04:00:00 Quote:
John Kallend flies fairly frequently with our club and has warned us
that *no one* has ever been able to build a LadyHawke that flew
successfully when they followed the plans in _RCM_. *The editors
modified the design for unknown reasons, and it doesn't work as printed.
able to send you plans to the *real* LadyHawke that will work much
better.
Jan 20, 2017, 09:53 PM
Flying R/C since 1964
kallend's Avatar
Thread OP
Quote:
Originally Posted by burkefj
John, there was a thread recently on rocketryforum that mentioned the ladyhawk design claiming that when RCM did the plans they changed a few things and made it almost unflyable, several people claim they never saw one fly right when built from the plans. Do you know anything about this, what was done wrong if there was, was it cg location or ? It appears to be a fairly simple delta and the cg location doesn't seem unreasonable at least on the picture I saw.

This was the quote...

by Greg Smi Wed, 14 Aug 1996 04:00:00 Quote:
John Kallend flies fairly frequently with our club and has warned us
that *no one* has ever been able to build a LadyHawke that flew
successfully when they followed the plans in _RCM_. *The editors
modified the design for unknown reasons, and it doesn't work as printed.
able to send you plans to the *real* LadyHawke that will work much
better.
Yes, they changed the wing section, the nose shape and the thrust lines. No idea why.
Jan 20, 2017, 11:05 PM
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burkefj's Avatar
Here is the cg location for the Phoenix RC RG.
Last edited by burkefj; Jan 21, 2017 at 09:04 PM.
Jan 21, 2017, 07:20 PM
Flying R/C since 1964
kallend's Avatar
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Quote:
Originally Posted by burkefj
Here is the cg location
Thanks.


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