GP-4 any advice knowledge etc needed
CW9371
I have a chance to buy a partionally finished GP-4 with hydrolicic retractable
landing gear. Please tell me all you can about this plane and the kit.
Anything and everything is relavant to me as I know nothing about this plane as
I was planning on do a harmon rocket 2, but this plane is partionally finished
and it might fits my needs almost as well.
Christopher Wilcox
CGW Insurance/Investments
Registered Investment Advisor
Jim
The GP-4 is all wood and retractable, the Harmon Rocket is all metal and
fixed gear. Quite a difference here. Whats your tool situation? (not
that I could answer any more of your questions as this is the extent of
my knowledge).
--
Jim Lewis
Now at http://www.lanset.com/lewy/default.htm
Just an opinion mindya
Jim
you have any specific questions about the GP-4 I can always ask George
when I see him at the airport. I don't often go up to him and talk to
him as he seems kind of above us little people sometimes (this is just
an impression I get) but I'll go out of my way if needed. I have to
drive buy his hangar to get to mine anyway.
Just an opinion mindya
> CW9371 wrote:
> >
> > I have a chance to buy a partionally finished GP-4 with hydrolicic retractable
> > landing gear. Please tell me all you can about this plane and the kit.
> > Anything and everything is relavant to me as I know nothing about this plane as
> > I was planning on do a harmon rocket 2, but this plane is partionally finished
> > and it might fits my needs almost as well.
> >
> > Christopher Wilcox
> > CGW Insurance/Investments
> > Registered Investment Advisor
>
> The GP-4 is all wood and retractable, the Harmon Rocket is all metal and
> fixed gear. Quite a difference here. Whats your tool situation? (not
> that I could answer any more of your questions as this is the extent of
> my knowledge).
>
> --
> Jim Lewis
> Now at http://www.lanset.com/lewy/default.htm
>
> Just an opinion mindya
I have also been gathering info. Hope this disorganized collection
helps.
Regards,
Alfonso Lebron
Alfonso Lebron <alle...@net-connect.net> wrote:
>Hello! I am new to this group but have been reading lots of very
>interesting postings during the past few weeks.
>
>I have been gathering information about the Osprey GP-4 and so far
>everything seems to describe this as a very good aircraft (although
>with a stall speed a bit above my preference). I have noticed here a
>very critical way of analyzing other homebuilt models and was wondering
>if any of you would have a comment about this aircraft, especially
>negative ones. This, I guess, might help me to make my mind regarding
>this wooden project.
Subject: Re: GP-4
Date: Thu, 10 Sep 1998 15:06:24 -0400
From: Ron Natalie <r...@sensor.com>
Organization: Sensor Systems
Newsgroups: rec.aviation.homebuilt
Yes very sexy. I talked at great length with Jackie Yoder
at Oshkosh and he showed me extensive photos and descriptions
of various things he did on the plane. Dave is right, lots
and lots of stuff to fab. Ask Yoder about how he made the
lens for the wingtip lights.
There's a picture and some other info
http://members.mdn.net/lpowell/ccandy.htm
I am also considering a GP-4 as my next project. The negatives as far
as I know are the time required to build, and the limited number
having flown.
Marty Hammersmith and I split the cost of a set of plans, and I've
looked them over pretty well, and there's nothing particularly
complicated about it, but there's one heck of a lot to it. There're
years and years worth of detailed components to fabricate.
There have been six flown I think, and one of those crashed. I don't
have the NTSB number handy, but what happened is that the canopy came
off and amputated the tail. Game over.
It's one hell of a hot rod.
I'm also considering an RV-8 since it looks like a big engined -8
might approach (but not mach) the GP-4 in speed, and will surely beat
it in the low end. I also have three designs of my own that are in
early stages of development, one of which might be built next.
The GP-4's advantages are speed, range, low expense (for the
performance), and sex appeal.
I have a stub for a GP-4 page on my web page, but haven't got around
to filling it in. If you come across anything that might well be
published there send it along and I'll put it up.
--
David Munday - mun...@muohio.noise.edu
My email address is not noisy.
Webpage: http://www.nku.edu/~munday
PP-ASEL - Tandem Flybaby Builder - EAA-284 (Waynesville, OH)
"Life is a constant oscillation between the sharp horns of a dilemma"
Alfonso,
I had the opportunity to talk with J. Yoder this morning. He had a few
things to say about the plans, and the plane it's self.
Jack told me there was a bit of a pitch sensitivity problem. He said
that
he wouldn't attempt to fly this one IFR.
Yes, he did get an autopilot, but it doesn't hold altitude well yet. He
has a few bugs to work out of it, and after it is done, it should work
well.
He's also looking at using a system that uses springs to make the
controls
a bit less touchy.
Another thing he explained is that the plane doesn't slow down. When
flying at altitude, he turns down the manifold pressure and the plane
slows
to 200MPH. When he points the nose down it climbs back up to 240 again.
I'm just trying to pass this along to you, because I have no experience
with constant speed props. Along the same lines, I don't have any
experience with retractable gear or high performance aircraft in
general.
I haven't even finished my private licence yet. All this means nothing
to
me at this point.
He did tell me that in landing configuration, the plane files as true as
any he's ever been in.
Thanks again.
Jerod Moore
Hello. I saw you posting on the r.a.homebuilt newsgroup. I, too, have
been collecting information on the GP4. I've been in contact with
Thomas
Evans, a GP4 builder, who had some helpful info.
>From what T. Evans could tell me, Jack Yoder is the authority on the
subject. You may have seen his page. His plane is named "Cotton
Candy", a
hot pink an maroon color scheme. Pretty unforgettable.
You can get his number from his site, it is (517) 832-2012. From what I
understand, he enjoys speaking with prospective GP4 builders. Tom told
me
that he paid twice as much for materials than Jack did, so finding
information about his suppliers should definately be worth the call.
> ----------
> From: Alfonso Lebron[SMTP:alle...@net-connect.net]
> Sent: Monday, September 07, 1998 11:36 AM
> To: Maj, Joe (JJ)
> Subject: Re: GP-4
>
> Thanks very much. You are adding something to my knowledge base that
> was
> not apparent from all the info. I had gathered.
>
> Regarding the pitch sensitivity and redoing the bellcranks, do you
> mean
> altering the controls to have a longer stroke in order to achieve a
> given
> degree of up or down elevator or something else? Pardon my ignorance,
> I
> guess everybody started at one point and I do not wish to make a false
> or
> worst start.
>
> Again, thanks very much for your help.
>
> Alfonso Lebron
Subject: RE: GP-4
Date: Mon, 7 Sep 1998 11:01:35 -0400
From: "Maj, Joe (JJ)" <JJ...@dow.com>
To: alle...@net-connect.net
Yes, I mean changing the throws so that more stick movement is necessary
for a given elevator deflection. Whether it is possible to harmonize the
feel of the ailerons and elevator I don't know.
One other factor, you need a big workspace to build this plane. The wing
is one piece and 22ft long. When you mate it to the fuselage you've got
to have a hangar size work area. Just logistics but something to plan
for.
Dr. Joseph Maj
>
>
> Maj, Joe (JJ) wrote:
>
A fellow in our EAA chapter built one of these.
Good points:
Fast
Stall speed quite reasonable ~ 50 kts in land configuration.
Strong structure
Bad points:
Cramped - You fold yourself into the airplane. Not much headroom either.
Not a "good flying airplane" - Ailerons become quite heavy at high speed
cruise. The airplane is very pitch sensitive. It takes a very light hand
on the stick to stay within the minimum requirements of the private
pilot checkride in regards to altitude control. Ham handed pilots will
have trouble maintaining +-1000 ft! Part of this might be cured by
redoing the bellcranks. But this is going to be a problem with any
homebuilt with a large performance envelope.
The Barracuda is not as fast as a GP-4 but it is a better flying
airplane, roomier too. The ultimate is the FALCO, but it is a very
complex, time consuming project.
Subject: Re: Falco -vs- GP-4
Date: Fri, 11 Sep 1998 23:47:08 GMT
From: mun...@muohio.noise.edu (David Munday)
Organization: http://www.supernews.com, The World's Usenet: Discussions
Start Here
Newsgroups: rec.aviation.homebuilt
Brian Mork <mo...@usa.net> wrote:
>
>BTW, what's a Periera GP-4? Any pointers to a web site?
I put a couple of pictures on my web page, and the midland Michigan
EAA chapter has articles of Jackie Yoder's plane.
The GP-4 is faster than the Falco, simpler or at least more
straightforward than the Falco, and I expect it'd be cheaper too. I
did a calculation once to see what the weight penalty would be to
build the whole thing out of Douglas Fir and it came out to a 14 lb
increase in the weight of the wood-pile you start with. Much of that
woodpile, and thus most of the weight differential too end up in the
scrap bin so the 14 lbs should be considered an upper bound.
The GP-4 also has more range than the Falco. If I build a fast wood
plane the GP-4'll be it. Some account the Falco as more beautiful,
but I don't see it. It's an entirely subjective matter so make up your
own mind on that scale.
Oh, and I got word the other day that Tom Evans Buick powered GP-4 had
a first engine run the other day. He may be the seventh to fly.
--
David Munday - mun...@muohio.noise.edu
My email address is not noisy.
Webpage: http://www.nku.edu/~munday
PP-ASEL - Tandem Flybaby Builder - EAA-284 (Waynesville, OH)
"Life is a constant oscillation between the sharp horns of a dilemma"
Alfonso Lebron wrote:
When I sent my original message, one week ago, I expressly wanted to get
negative points. I got them and certainly it opened a desire for a
Falco, since It
was suggested that
this was a plane to be very much taken into consideration.
No need to ask that I went directly to find info. about that chick.
This is what I found:
The Falco has very sensitive controls.
The GP-4 too.
The Falco stalls at 75 MPH clean.
The GP-4 does it at 65.
The Falco stalls at 62 MPH in land. config.
The GP-4 does it at 62 too.
The Falco max. speed is 212 MPH with a 160HP.
The GP-4 does 250+MPH with 200HP.
The Falco max. speed is 240 MPH with a 180HP.
The Falco 75% cruise speed with 160HP is 190MPH and 198MPH with 180HP.
The GP-4 at 75% cruise goes at 240MPH with a 200HP.
Other things that called very much my attention is that the Falco LACKS
the sensation of stick forces changes
when increasing or decreasing speed, which can be a trap if not paying
very
careful attention to the speed indicator,
especially when landing. These stick forces (or lack of it) do not seem
to
be a similar problem in the GP-4.
When the GP-4 enters a nose down attitude, it gains speed very rapidly
due to its
cleanliness. The
same thing happens with the Falco. Hence, plan with anticipation a
descent for not
to get into the
Vne unadvertently. I guess this is similar for most clean, high
performance crafts.
The GP-4 costs about 50K or even less. The Falco easily goes beyond 80K.
I spoke this morning with Mr. George Pereira and he explained to me that
it
is true that the ailerons become heavy above 190MPH but the force needed
to
move them at that speed and up to 250MPH, is reasonable. In any case you
would not
want a
very sensitive control that with very little effort could make you get
into
a high G maneuver at high speed (any resemblance with the RV-8?) with
the
risk of a catastrophic structural failure.
He also told me that the pitch problem was due to sensitivity of the
elevator controls but that this was relatively easy to fix with an
autopilot or with trim if considering long cross country trips or light
IFR flying.
He recommended having TWO autopilots (longitudinal as well as the axis
that goes
from tip to tip of the wings (horizontal?lateral?) and he knows of a
friend who has
a GP-4 with this config. and flies it IFR. However, he always mentioned
LIGHT IFR.
Don't get into a thunderstorm in this configuration.
A matter of personal taste, the Falco is unquestionably a beautiful
aircraft but the GP-4 too.
I will stick to the latter. If there is still anymore negative comments
about the GP-4, please let me know.
Thanks for all your comments.
Alfonso Lebron
CW9371
>The GP-4 is all wood and retractable, the Harmon Rocket is all metal and
>fixed gear. Quite a difference here. Whats your tool situation? (not
>that I could answer any more of your questions as this is the extent of
>my knowledge).>
Jim, I really hate to do this. But I really appreciate that advice. I think I
know the difference to that extent. wood is different than metal, retratable
landing gear looks better. See I am even a litle a head of you.
lol
Please i am looking for some real advice and knowlegdge here