pen knife
11-07-2002, 12:40 AM
#1
Member
Thread Starter
My Feedback: (2)
Join Date: Jan 2002
Location: Oxford , Mississippi
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
Can anyone tell me what moter ,prop to make it do some 3D..
How do they fly? I think I will get one because I have a realy good running 25fp an some mini gear.. :idea:
How do they fly? I think I will get one because I have a realy good running 25fp an some mini gear.. :idea:
11-07-2002, 03:06 PM
#4
Senior Member
My Feedback: (1)
Join Date: Jan 2002
Location: Wichita Falls, TX
Posts: 240
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
I built two with TT GP 42s in them. The GP 42 weighs the same as most .25s and has 1.1 hp. It flies the plane great and doesn't add any weight. It's one of the best weight/power ratios I've flown. The completed plane came out at 3lb 3oz. One of the best things about it is you can still use 3 or 4oz tank and get plenty of flying.
You'll love the pen knife. It flies as well or better than most .40 size planes. Just make sure that .25fp has enough hp.
You'll love the pen knife. It flies as well or better than most .40 size planes. Just make sure that .25fp has enough hp.
11-07-2002, 03:14 PM
#5
Senior Member
My Feedback: (4)
Join Date: Feb 2002
Location: Arlington, MA
Posts: 603
Likes: 0
Received 0 Likes
on
0 Posts
Should be ok...
I've flown the Pen Knife with an ancient 25 FSR (I bought the engine in the mid-eighties) and it flew fine... I also used a 32 FX.. both are fine.
For some Pen Knife vids and picts:
http://archive.ncsa.uiuc.edu/Cyberia...pen_knife.html
-Juhan
For some Pen Knife vids and picts:
http://archive.ncsa.uiuc.edu/Cyberia...pen_knife.html
-Juhan
11-12-2002, 03:00 AM
#6
Member
My Feedback: (1)
Join Date: Sep 2002
Location: Tampa, Florida
Posts: 76
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
5 years ago i built my first penknife and from five years of flying this plane i found a 32 OS SX with a macs pipe .
the thing will come apart at full throttle if your not carefull and hovers perfectly OS 32SX is so reliable only time it dies or cuts out is on low fuel.. i even put snow skies made out of coro plastic to land in the snow
tons of fun and easy to fix..
you can fly this thing in tiny fields
i love it
the thing will come apart at full throttle if your not carefull and hovers perfectly OS 32SX is so reliable only time it dies or cuts out is on low fuel.. i even put snow skies made out of coro plastic to land in the snow
tons of fun and easy to fix..you can fly this thing in tiny fields
i love it
11-16-2002, 10:43 PM
#8
Senior Member
My Feedback: (2)
Join Date: Jan 2002
Location: Nashville, TN
Posts: 2,924
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
I have a TT four stroke 54. I think it is .8 hp. Would that be a good engine for this plane? I also have the option of buying an Irvine 37 at a good price. Any thoughts?
11-17-2002, 12:44 AM
#10
Senior Member
Join Date: Dec 2001
Location: Bedford, MA
Posts: 1,167
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
Originally posted by Billy Hell
I have a TT four stroke 54. I think it is .8 hp. Would that be a good engine for this plane? I also have the option of buying an Irvine 37 at a good price. Any thoughts?
I have a TT four stroke 54. I think it is .8 hp. Would that be a good engine for this plane? I also have the option of buying an Irvine 37 at a good price. Any thoughts?
11-17-2002, 01:22 AM
#11
My Feedback: (28)
Join Date: Feb 2002
Location: Union City,
TN
Posts: 1,425
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
Billy, I had an Penknife with OS 32 that I got from Gator. It used 4 standard servos, 1 mini on throttle, hitec rec, and 5 cell- 600 mah battery. It was an blast to fly. Gator has some pic's of it.
I don't think the 54 will be an good choice for it.
I don't think the 54 will be an good choice for it.
11-18-2002, 01:26 AM
#14
Join Date: Feb 2002
Location: Suwanee,
GA
Posts: 87
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
Built one of these after wanting one for quite a while. FANTASTIC portable flyer. Keep the wieght low - mine came in - I think a hair less than 3.5 lbs.
Anyway the guys at the field loved it so much - I get to frame up 2 more for them :0 such a deal!
Anyway the guys at the field loved it so much - I get to frame up 2 more for them :0 such a deal!
11-18-2002, 01:57 AM
#15
Senior Member
Join Date: May 2002
Location: Northern,
OH
Posts: 387
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
Hmmm...thinking about one with a bushed .40. Would the wing hold a 6 oz. tank ? From what I've read here they can use the nose weight. Think I could make 3.5lbs with a .40 and standard servos ? I like the portability factor of this plane.
11-18-2002, 04:32 AM
#16
Senior Member
My Feedback: (2)
Join Date: Jan 2002
Location: Nashville, TN
Posts: 2,924
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
I'm thinking the same thing. If I could get away with using Hitec 300s at $10 a pop that would be much better than using HS81 metag gears at what...$30 a pop or $39 a pop? Then I'd put the Irvine 37 on the nose and finish it off in a Jose Cuervo trim scheme.
11-18-2002, 04:43 AM
#17
Senior Member
Join Date: May 2002
Location: Northern,
OH
Posts: 387
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
Well build one first and let me know Billy ! 
You can be our Guinea pig !
I was thinking the same thing. Micro servos are cool, but the prices aren't !
You can be our Guinea pig !
I was thinking the same thing. Micro servos are cool, but the prices aren't !
11-18-2002, 05:08 AM
#18
My Feedback: (33)
Join Date: Jan 2002
Location: Mooresville,
NC
Posts: 723
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
i want one bad, i ahve the mini servos and os .32 engine w/ mcp but no plane or $$ 
lol sucks to be broke
anyone have a kit they don't want let me know
thx
chris
lol sucks to be broke
anyone have a kit they don't want let me know
thx
chris
11-18-2002, 05:43 AM
#19
Senior Member
My Feedback: (4)
Join Date: Feb 2002
Location: Arlington, MA
Posts: 603
Likes: 0
Received 0 Likes
on
0 Posts
standard servos are fine...
You'll be fine with standard servos and a solid 25 ball bearing engine. I've flown the Pen Knife with both standard hitec 300 and mighty micro 225s (not metal geared) and both worked without problem (with OS 25 and 32 engines). The only issue with non-metal geared mini/micro servos is stripping... not in air but if you happen to brush an aileron or rudder on the ground.... then the mini plastic gears will shred. So use 225 MG or the bigger plastic geared standard servos (like the 300s or 148s).
-Juhan
-Juhan
11-18-2002, 03:17 PM
#20
Senior Member
My Feedback: (2)
Join Date: Jan 2002
Location: Nashville, TN
Posts: 2,924
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
Great! Thanks for the input. I'm anxious to get get going on mine. What about the weak fuse. I hear that the weak spot is at the leading edge of the wing. Should I reinforce it there?
11-18-2002, 05:27 PM
#21
My Feedback: (68)
Join Date: Feb 2002
Location: Alvin, TX
Posts: 199
Likes: 0
Received 0 Likes
on
0 Posts
Help Tech info on Penknife
Need tech info
I have a scratch built Penknife that I am finishing. I do not have plans.
I need the dimensions on the ailerons, elevator, and rudder.
I also need the cg for those nice flat spins.
Thanks
Greg
I have a scratch built Penknife that I am finishing. I do not have plans.
I need the dimensions on the ailerons, elevator, and rudder.
I also need the cg for those nice flat spins.
Thanks
Greg
11-19-2002, 03:10 PM
#22
Senior Member
My Feedback: (4)
Join Date: Feb 2002
Location: Arlington, MA
Posts: 603
Likes: 0
Received 0 Likes
on
0 Posts
weak spots...
In all planes, there are particular stress points... and in the Pen Knife, I've found those areas to be at the very edge/end of the front hardwood doubler that wraps around 1/2 of the wing leading edge. Both the top and bottom end points of this doubler are stress points (where the doubler ends and balsa takes over). Maybe a CA'ed thin piece of fiberglass would help... but I'm not too sure.
The plane is durable.... very durable. I landed mine from inverted flats, inverted dead sticks (at 3' off the ground and didn't have time to roll over), etc and never had a problem... unless I really whapped the plane into the ground.
-Juhan
The plane is durable.... very durable. I landed mine from inverted flats, inverted dead sticks (at 3' off the ground and didn't have time to roll over), etc and never had a problem... unless I really whapped the plane into the ground.
-Juhan
11-20-2002, 04:23 AM
#24
Member
My Feedback: (-1)
Join Date: Jun 2002
Location:
Posts: 39
Likes: 0
Received 0 Likes
on
0 Posts
pen knife
i have flown one with the mvvs.21 but i have the mvvs .28 and it is perfect power plant IMO. I love that engine and it has plenty of power to hover and accelerate out. Now with all the fixes though, where it did break right behind the front plywood doubler and some other minor stuff it still hovers great and has plenty of power. BUt i could feel the couple ounces. I feel this is the perfect combo. I love the plane.