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Oct 08, 2006, 01:45 PM
Retired CAD guy
birdofplay's Avatar
Thread OP
Build Log

Pterra CAt

WAAAY back in July, in the Harpy thread I offered this design ...

Since then the idea has been smoldering, UNTIL NOW !

I went ahead and built one just to answer the question ... Will It Fly ?

It's a 24" span design built from 6mm depron for the wing and Fins.
I used some .125 RCFoam for the "Head" but 3mm Depron also work fine.
I cut all the parts on my ShopBot CNC so CAD files will be available.

After major part assembly exclusively using Loctite's new SUMO glue,
I coated everything with waterbased clear satin Olympic polyurethane
then spray painted the colors over that.

A couple of small servos, Small RX, a CC-TBird 18 and a Komodo 257 round
out the equipment. Pick a prop to suite your winding and flying choices.

UAW with a CommonsenseRC 800ma 3s1p Lipo is only 10 oz

With less paint and a smaller RX, lighter motor mount and prop hub
it could easily become less than 10 oz

Control surfaces are hooked up "Chara Style" just like the Harpy.
See pix in next post.

I've only used straping tape on the bottom of the 6mm wing for bracing.
i.e. no CF spar. This has worked for months now, on my Harpy,
which flies much faster and pulls more G's than I expect for the Pterra Cat.
I did use a central SPINE for "endo" strength. I got really tired of creating accordians with these designs during preliminarys.

Vid of maiden will become available as the weather clears.

I expect at least a few more Flyable days before the rainy season here in the NW.

I will get back with a CG location after flying.

Thats all for now
Last edited by birdofplay; Sep 07, 2014 at 11:40 AM.
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Oct 08, 2006, 09:40 PM
Registered User


Like the look... I love flying animals. Did the Depron Dino... well not a true dino but nice flyer. 28 inch span. STRINGFLY <>+++++
Oct 09, 2006, 02:03 AM
Retired CAD guy
birdofplay's Avatar
Thread OP
Kewel ! I LIKE IT too :-)

I'd been doing Alley Cat and Harpy ( Cat like) etc

So I thought I'd try a Dino in Cat like format.

Your's looks like it'd be a nice floater.
More realistic Looking too.
Did you do up plans ?

Mine is spoz to be just menacing or bizzar :-)

It rained here all day, so I dont know how mine is gonna fly yet.
Last edited by birdofplay; Dec 17, 2013 at 09:04 AM.
Oct 10, 2006, 02:21 PM
registered foam addict
chara's Avatar
Hey BOP that's looking phantastic!!! really nice, and cool paintjob! congratulations!
I'd really LOVE to see that one in the air! waiting patiently for the video!


I've been "off" for a few days now and you are partially "responsible" for that
Your pics of the aerotow-stuff got me so much hooked on sail planes that I ended up now searching for glider pilots schools to make a glider pilot license .
we have great places here around the alpes to fly in.
Oct 10, 2006, 02:37 PM
Retired CAD guy
birdofplay's Avatar
Thread OP
Chara: It's WINDY again today :-(

You are Too late for Fiss this year.

Glider stuff kinda got its START by Bavarians throwing themselves off the Alps
Theres very Nice place in Kufstein ( maybe 75-80 KM from you )
and of course there is always Wasserkuppe.

I bought the full sized Windrose plans 15 yrs ago and intended to build a BIG one but
I decided to DO a 1/4 scale to see how things went together 1st.
THAT was as far as it got :-(
I went for the Pilots license instead of building adn drove a PA-28 around for
a few years.

Vids as soon as possible.
Last edited by birdofplay; Dec 17, 2013 at 09:04 AM.
Oct 10, 2006, 02:50 PM
registered foam addict
chara's Avatar
cool stuff BOP, are you still flying (full scale)?
wind rose looks cool!

have you ever thought about making a small foam glider? I have one on my wish list. about 1.20m wing span so it fits in my trunk.
I've made some calculations. weight should come in around 180g. with 11g/dm^2 wing loading. probably good enough to ride some thermals in the summer

hey what about the ptera-cat with glider wings?
Oct 10, 2006, 08:24 PM
Retired CAD guy
birdofplay's Avatar
Thread OP
Chara : I'd like to DO a Buzzard or similar with centered prop powering it.
We have lots of Buzzards here in the summer.
I spoz we could pterrorize the Buzzards with a larger span PTCat :-)
Are you thinking something like STRINFLY's PTbird except a very light version.

Sold my Pa-28-180 a few yrs back before retiring from Bayer AG.
Havent flown myself since. I guess after awhile ...
Been there Done That - plus the rising expenses - wheeew !

OK now the N E W S !

It does actually FLY ! Winds subsided this afternoon so out I went.
It's pretty much an AlleyCat like flier.
As the vid shows I failed to switch to LOW RATE for the 1st flight :-(
Quite a handfull until I settled down and eventually discovered my mistake.
Nice and smooth after LOW Rate was selected - wheew.

BTW I detected NO adverse YAW effects from the NOSE PIECE !
It actually tracked pretty darned well :-)

The landing was a bit abrupt as any headwind had just STOPPED.
IT came down like a NOSE heavy critter.

The Tropohengus was right ! the nose piece needed a bit more "Attachment" area.
That landing broke it downward a bit. The central spine worked to save the nose and actually stayed glued to the bottom aftwards.
It split off slightly at the nose.
I Intended to do a slow nose up to low alt and flop it on, but ... well :-}}}

I'll just glue it back together and add some bracing towards the rear.
Last edited by birdofplay; Sep 21, 2011 at 06:16 PM.
Oct 11, 2006, 05:12 PM
registered foam addict
chara's Avatar
cool video! and great save after the toss
looking mean! I bet those buzzards are going to have a heart attack when it pops up behind them
With a large wing it wouldnt look so bad either. It would make it a nice floater I believe. hmm.. maybe removable wing extensions?

file size is a matter of resolution (number of pixels) and compression algorithm (so called codec). Normally I go with a resolution of 320x240 for file sharing and around 640x480 if I want to store it on HD or DVD (produces 4 times bigger files).

The codec and compression rate is very important. modern coding algorithms give excellent video quality and very small files sizes. Best one is DivX IMHO. However I mostly use the windows xp inherent "movie maker" which produces OK quality and is easy to use. just choose the resolution and the target file size. rest is done by "movie maker" . it also allows you to cut and edit your video footage. not so bad for a "Micrischrott"* product

*now go figure what that means

Last edited by chara; Oct 11, 2006 at 05:22 PM.
Oct 11, 2006, 05:57 PM
Cool design. I too like flying animals they have a certain appeal to them. Tried viewing the vud but all I get is this..... Any ideas?
Oct 11, 2006, 06:32 PM
Retired CAD guy
birdofplay's Avatar
Thread OP
Thanx Chara.
It was a SAVE fer sure :-)

What kinda of "scheme" do you have in mind for a removable wing tip ???

Waterboy: Not sure whats up with QuikTime but my file is an MGP file type.
Could be Quiktime doesnt lke the file size. I dunno
Sorry for the size - I was going for quality.
Try Windows Media Player if you can.

As it is I have cut out LOTS of kewel portions of the vid as well as
my scrolling Title as it just got too large !

If everybody HAD access to FREE divix decription and encryption
then we'd all be using them, eh ?

All that I have found are some TIME OUT shareware version and OF COURSE
they "Want To BOND with you" . for cripes sake.:-(
Oct 11, 2006, 06:44 PM
Registered User
OhioMike's Avatar
Hey Stringfly, i always wanted to build a pteradactyl RC bird, only problem is theres a lot of Hawks in these parts, i give it a 2 minute life expectancy. Did you ever do up plans for it? Thanks.
Oct 11, 2006, 08:49 PM
Registered User

depron dino

Here's the thread on my dino flyer and plans.
Correction.....Was a 32 span. Flew fine but needed a little bit more motor... a Fiego would be a better choice.

birdofprey.... glad it flew fine. All the cats seem to do well. I have plans for a big buzzard and a Seagull may have to try it. STRINGFLY <>+++++
Oct 11, 2006, 08:54 PM
Registered User


Tried a flew but not very well... finally died a horrible death at a indoor meet. STRINGFLY <>++++
Oct 11, 2006, 11:21 PM
Retired CAD guy
birdofplay's Avatar
Thread OP
LOL :-))))
String you GOT ME on that one !!!

Actually kinda of a shame it didnt fly.
For a squirrel it looks pretty cute .

But seriously folks
Buzzard and Seagull sound TOO KEWEL ! ! !
More motor is NOT a problem :-)
I'm got your Pteradon plans just a sec ago :-) Thanx
It looked so much heavier in the COLORED version than in White foam !

OK .. now where are the buzzard and/or Seagull ? thanks

Chara !!! you listening to this ?

OH !!! and ... I got two more flights out of the Pterra Cat this PM !
I discovered that this bird NEEDS power for good control.
I gotta work on WHY next.
Still it's stable enough to have a ball with !
Just leave enough juice for a nose high landing :-)
Last edited by birdofplay; Oct 11, 2006 at 11:28 PM.

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