Web: www.poorboyaviation.com E-Mail: hartungj@srt.com
PoorBoy Versions 090708 Pg-5
Ultralight type planes have gone through continued development starting
somewhere in the 1970’s. A rediscovery of the basic fun and experimentation
produced a transitional progression of development that the law of the land
didn’t quite know how to keep up with, that led to a mess as the Federal
Aviation Administration (FAA) tried to regulate the airspace. People were
soaring down hillsides with hang gliders, small engines on the hang gliders
appeared and the FAA came up with the 155 lb foot launch rule. Next came the
hang glider with a seat and wheels, larger engines and a accompanied weight
increase of airframe and the part 103 254-lb rule came into effect to cover this
basic level of machine. The developmental progression didn’t stop or even slow
down but the FAA did, the FAA seemed unwilling to allow further development and
the part 254 lb rule held for about the next 20 years. Other countries (Canada,
England, France, Germany, etc.) progressed in the 1980’s and 90’s with Micro-
light categories in their laws allowing for the additional development of the
Ultralight movement, the US rules didn’t change until October of 2004 and
finally gave a new breath of life to aviation with the Sport Pilot Category.
The Sport Pilot License and associated Light Sport Aircraft (LSA) is the current
rule. The Ultralight rule was fortunately saved (thank God) and the FAA left
the 103 rule in place. This is my quick and probably narrow description of
what has taken place on the Ultralight scene in the last 30 years and is not
inclusive nor exactly accurate. I offer this description in order to introduce
the different models of the PoorBoy.
Most single place fixed wing Ultralight aircraft in the past 20 years
(probably greater than 95%) were overweight but otherwise would meet the Part
103 rule. The obvious reason for this is airframe strength, most designers were
unwilling to cut the airframe formula that close to the safety margin of the 254
lb weight limit. There are 254 lb. Legal Ultralights that have had reasonable
safety history’s build in the past and still offered in the present but it is
difficult to keep them that way. Some designers break the rule or give false
information, try to find ways around it by not having niceties like breaks or
windshields etc., and others simply refuse to offer a claimed 254 lb. 103 legal
model. It should be obvious that if you plan on building a 103 legal “254 lb.”
Ultralight that you cannot let its weight grow with additions or you miss the
point of the 103 legal effort in the first place.
The PB-U 103 legal PoorBoy single seat aircraft is being revisited, in the
past I have explained how to keep the current pusher 103 legal but did not
supply proof in the form of a flying prototype. I hoped to release a flying 103
legal ultralight called the Penny Piper, it would be built with the sole intent
of demonstrating a part 103 legal set of plans, it should fly in the 24 knot min
stall and 55 knot top speed envelope. I am not sure I can even do a 103 254lb.
version, or that I am willing to put out that much effort, so please don’t hold
me too it.
We would like to offer a PB-U that is 254 lb. legal by limiting airframe weight
and of course engine choices, you should limit the engine when the airframe is
lighter to keep the speed and total weight down and therefore limit stress on
the airframe, hopefully this prototype could be available in the future and the
Penny Piper may turn out well. I personally don’t like 103 Ultralights because
I prefer the standard model PB-1’s safer airframe and I don’t recommend the PB-U
unless you are determined to build a 254 lb. 103 legal model. As I see 103 254
lb. planes they usually miss the mark in weight or soon do after someone adds
anything like windshield, brakes, or instruments. Once you miss the weight goal
then the exercise of shooting for strict 254 is pointless and you may then have
a limited strength airframe structure. The PB-U is not a real plane, please
ignore the PB-U references that you see imbedded in the plans.
090708 Pg-6
The PB-1 is the standard model and will come out heavy by the 254 lb. rule,
the PB-1 can fly in the 103 envelope in every other part 103 requirement.
The Poorboy project: We have designed, built and flown the time off the PB-1
prototype. It costs a good bit of money and effort to bring a version of the
plane into existence, I explain this so that those of you who are interested in
Poorboy’s will understand additional prototype models are limited in the real
world of time and money.
Performance: The range of performance is going to be similar to most of the
Ultralights you see on the market varying of course by the amount of power
applied. A few planes like Titan are meant to be clean and fast by design,
the Poorboy is not one of those. Poorboys have a low aspect wing and are
meant to perform in the Ultralight flight envelope, they will go faster but
fuel economy and engine life are matched to the best overall function without
excessive effort on streamlining, we keep it in the Part 103 flight envelope.
Wing tip choice will effect stall speeds and so will aileron rigging. The
PB-1 prototype w/droop tips and a 200 lb. pilot stalls at 26 to 27mph. (28mph is
max stall speed for Ultralight).
Wing Tip Options.
There are four wing tip configurations you could use.
1. Cut tip. This is the wing just ending flat with no “tip”.
The Cut tip is a bit faster for speed due to less lift, it has a
higher stall speed also. .
2. Rounded tip. 16” to 18” rounded bow, adds 2.5 ft to wing span.
The rounded tip adds to lift by decreasing spill around the end of the
airfoil and increases the wing span, the rounded tip is a common type
of wing tip.
3. Droop tip. Nice looking, adds 1 ft to span.
The droop tip adds to the lift a good bit, decreases the stall as well
as increase lift, increases drag and may slows the upper end speed
some (looks cool).
4. Flat plate tip. Attached to “cut End” and is oversize to the
airfoil and adds to lift performance. The flat plate tip adds to lift
by damning the wing end and limiting air migration around the tip, it
adds lift similar to a droop tip because it is larger than airfoil
size, it is inexpensive and does not increase the wingspan. The flat
plate tip is easily removed and re-attach if you wanted to fly in the
cut tip configuration.
PoorBoy uses a USA 35B airfoil (but significantly modified in application),
attached baton style rib on 8” rib spacing (to limit scalloping on dope and
fabric wing), cable linkage on rudder and elevator, push/pull torque tubes
for aileron control.
The Prototype PB-1 uses a Rotax 503DC and the information about the PB-1 is
based on that configuration. Performance numbers on any plans built Ultralight
will change depending on how the ailerons are “rigged”, wing tip choices, and of
coarse the engine choice (40hp Min. to 52hp 503DC).