开云体育

Has anyone else noticed the resemblance between the Cessna O-2 Skymaster and the Mariah! T-100D?? Aside from the push-pull tractor prop and retractable gear, the Skymaster is pretty much an overgrown Mariah!? I wonder which came first?......by Bill Storto 03/06/2020

After a quick bit of research, I guess I can answer my own question.? The civilian Skymaster first flew in 1961, predating the Mariah! by 21 years or so.? I guess Gene liked the Skymaster as much as I do, as it's distinctive tail booms and vertical stabilizer shape are reflected in the T-100D.? The U.S. military must have liked it, too, as they commissioned? the O2 version of the Skymaster which remained in service for a number of years during the Viet Nam conflict....by Bill Storto 03/06/2020

Bill,

Sorry for the late reply, I have been offline for several days, but back now!? Yes, the Cessna Skymaster came first.? The Skymaster was a favorite of Gene Turner, he really like the twin boom design and incorporated this into Mariah.? I really like the 337 version of the Skymaster and have looked at some to purchase.? The one that was in my price range had sat for a couple of years and was out of annual.? It had low overhaul times on the engines too and the weren't asking a lot for the plane.? The problem is that the maintenance cost might eat you alive!

Another design that came about around the same time of the T-100D Mariah was the Canaero Toucan.? The Toucan came after Mariah was designed, built, flown and offered as plans to the homebuilt community.? The big difference is that the Toucan is a push-pull just like the Skymaster.? It was a nice design, look here:?

Take a look at this design:?
This is Mariah on steroids!? I have often thought what a beefier, tandem Mariah would look like and I saw it in this design.? BTW, we do have a builder in South Africa!? I think they looked at our plans. :-)

Ride the WInd!

Ken

Ken,

I REALLY like the Mwari - thanks for making me aware of it!? One of my favorite ultralights is the Sadler Vampire by Bill Sadler, first flown in 1982 which was apparently a good year for ultralights!? It was bought out by the miltary, I believe, to make into UAVs which really started the killer drone movement.? The design was picked up by an Australian outfit that powered them with Jabiru engines, but didn't really stick to the part 103 guidlines that Bill built to.? I believe only about 20 examples of Sadler's original Vampire still exist.? I am sure Gene was aware of it because it would have directly competed with his T-100D of the same year, and is an obviously similar design.? It was all-metal and cantilever, which made it very sexy for a true part 103 ultralight, and I suspect that the Mwari people were aware of it, too.? Some South American countries were marketed a militarized version which looks suspiciously close to the Mwari....by Bill Storto, 03/09/2020

Bill,

Ken,

I found an Aerosociety paper online that had a pretty good overview of Whittaker's designs.? The MW2 really seemed to be the high point to me, with it's ducted fan, or "propulsor" as he calls it, and cantilever wing.? It looks like he took a step backwards on his next several designs, perhaps seeking a more conventional testbed for his "universal tail joint" (yikes!) and "control mixer."? ?I think he got back on track with the MW8.? His MW9 and MW10 may be his best work, but zero-sweep flying wings always looked inherently pitch-unstable to me.? In sailboat design there was always a huge "looks right - is right" factor that seems the same with aircraft, and the no-sweep flying wing flunks that test to my non-aerodynamicist's eye, just as forward-swept wings give me the willies.? They might actually be perfectly safe, but the pucker factor would be way too high for me to enjoy flying one.? At least the Mitchell wing was swept, as I recall, but I have no desire to test my nerve even in so much-flown a craft.? Gene's T-100D falls within my understanding of how airplanes fly, so even if things go wrong, like an inadvertant spin, I can apply what I know to fly my way out.? Flying wings look like they could tumble, and I'm not sure I could deal with that.....by Bill Storto,03/10/2020

Ken,

Speaking of twin-boom aircraft,? if I had the parking space that I suspect you have at work, I would have to have a bumper sticker that said W W K D (What Would Kelly Do)......by Bill Storto, 03/11/2020

Bill,

Bill,

Ken,

Don't sweat the typos - I thought I was right uptown when I got my current "flip-phone" upon which typing anything more than a directory entry is practically impossible.? I had it for several years before my granddaughter pointed out that it contained a camera.? If I had known that I was going to live this long, I would have learned to use an i-phone.? Another good thing about ultralight flight, to these old eyes, is that despite the wonderful safety advantages of ADS-B for traffic and weather, one has to be conversant with I-pads and i-phones, which I am not.? One can still have a steam cockpit with part 103.? Just to show what a dinosaur I am, when I saw Whittaker's "universal tail joint" my first thought was of the old Voisin "box-kite" biplane with it's one-piece canard empenage, which I also thought was pretty scary.? I just try not to call gentlemen younger than 55 "sonny."......by Bill Storto, 03/11/2020

Ken,

After checking my facts against my computer, it turns out that the early aircraft I was thinking of with the one-piece box-like canard empenage was the Santos-Dumont 14-bis.? The Voisin was similar, but it's canard was more cruciform, with apparently independent elevator and rudder.? While the Voisin has been described as only "marginally controllable." the Santos-Dumont 14-bis looked absolutely terrifying.? The word "floppy" comes to mind, to me not a desirable trait in aircraft structure.? The later Voisins took on a look similar to the DeHavilland DH-2, which I thought looked pretty flyable but was referred to by it's pilots as the "spinning incinerator."? I think Santos-Dumont was better at lighter-than-air, but I guess that's how progress is made......by Bill Storto, 03/11/2020?

I hope I don't sound like I'm denegrating Santos-Dumont's genius in any way.? His later Demoiselle was of much more "conventional" configuration, and in photographs of it at rest, the entire cruciform empenage is drooping in such a way as to suggest a "universal tail joint" similar to Whittaker's MW-4.? At flying speeds, the air flow would have lifted the tail structure to neutralize or at least lighten control forces.? My apologies, Alberto......by Bill Storto,03/12/2020??

Ken,

The Ion is indeed a beauty, but out of my range on a number of levels!

Regarding Mark Stull's tragic accident, I have a theory based on what I saw on his annular tail design and the report of the crashed aircraft having a "large, box-like tail."? I noticed rather long arms on the mass balancers on his ring tail, and I'll bet that he had a similar arrangement on the box tail.? Remember the short, heavy mass balancers on the P-38 elevator?? Lots of mass balance on very short aerodynamic lever-arms.? I believe that Mark was trying to save weight, so he used light weights on long arms, which was great for static mass balance, but in flight they created a potentially powerful aerodynamic lever in the transverse (pitch) axis.? While not a problem at low elevator angles of attack, I believe that in trying to level off after a high rate of climbout on takeoff (which he said that his aircraft was capable of in his interview) he pushed the stick well forward to stave off the stall which witnesses said was occurring.? This pushed the two mass balancer arms up into the propeller wash, forcing them up and back? which pushed the stick even further forward, perhaps even snatching it out of his hand.? This dynamic overbalance condition produced a quick and severe nose-down attitude (the "flip" reported by witnesses) which from 50 feet AGL was unrecoverable.? His hydraulic damper probably limited travel in the vertical axis enough to prevent such a snap overbalance from causing spins, but with no such limiting device in the horizontal axis, a loss of control resulted.? I have seen this occur on tiller-controlled highly-balanced spade rudder sailboats, when the helmsman came about too sharply and a dynamic overbalance ripped the tiller from his hands and resulted in the boat spinning into an uncontrolled (and sometimes catastrophic) jibe.? This doesn't happen on wheel-steered boats nearly so easily because of the travel-limiting effect of the mechanical advantages and losses of the steering system.? I believe I have heard of similar overbalances in aircraft with all-flying elevators during icing tailplane stalls.? Well, it's just an idea; you're the engineer.? I might be just talking through my hat......by Bill Storto, 03/14/2020

Just to clarify, all the axes i was speaking about are of the tail itself through the "universal Tail Joint," not of the entire aircraft.? ?I wrote this pretty late at night (or early in the morning) so my terminology might be pretty muddy.? I figured that you would sort out what I was trying to say.......by Bill Storto,03/14/2020

Bill,

I had reviewed Mark's designs at the time he was building them all those many years ago and followed his threads on homebuilt.com I had to reread a number of his posts to get his understanding of what he was thinking about with his designs.? Unfortunately, he didn't say much about this last design because he didn't want to give away the design secrets until he had finished building and flight tested this aircraft.? Knowing that Mark reused a lot of parts from one design to the next and back again, I would say that your assumption of his reuse of the?long mass balancers he used on his ring tail is accurate.? With that said, I really don't know anything about the design in which he was killed.? Other than the fact that someone reported that it had a boxlike tail, I really don't have a basis for an accurate opinion.? Mark did use the long mass balance rods to potentially stop flutter that he thought he was experiencing on his ring tail design.? The strange thing that I couldn't understand at the time was that I didn't think his ring tail suffered from flutter, still don't.? Ultralight aircraft do not fly in the speeds that generally cause flutter to occur in an airframe.? This is what I think, I think that the design lacked adequate structure in the rear of the aircraft to stop the yawing and pitching of the tail.? The tail moved around a lot apparently, both side to side and up and down.? I believe he even said that it drooped and traveled at least a foot with under 1G.? This tells me that this aircraft wasn't designed accurately enough to support the loads that it had to carry.? Not knocking him at all, his work was truly amazing.? Back to the?long mass balancers that he used.? If he did reuse them on the box tail design, and I don't know that he did, it possibly could have caused the scenario that you have related in posts #29.? I believe that having the engine in a pusher configuration may have potentially caused this to occur as well.? Mark didn't seem to have any issues with the mass balance arms in the Ring Tail design which was a tractor rather than a pusher design.? The pusher configuration totally changes the propwash and airflow over the rear of the aircraft.? I could see them possibly causing the issue that you have written about.? But, I am just speculating at this point.? But, it is good to look over instances like this to learn.

About the P-38, Kelly Johnson never thought that the P38 suffered a flutter problem. What was interesting is that he stated, "The external mass balance did not help al all."? The problem was determined to be the center of pressure moving back towards the tail when in high-speed maneuvers.? The fix for this was to add dive flaps to the aircraft in order to keep the lift working properly across the top and bottom sections of the wing.? A friend of mine works with heritage aircraft and is the keeper of the keys to our vault.? He has told me some amazing stories and I have been able to see some interesting documents over the years.

Ride the Wind!

Ken

Ken,

Thanks for your insights about Mark Stull's accident and my analysis of it.? I can see how a structure as flexible as that could develop some in-flight deformation that goes way beyond "flutter" and could result in catastrophic losses of control and/or mechanical integrity.

Speaking of catastrophic situations, do you have any thoughts on BRS chutes?? I see that the T100-D plan notes recommend wearing a helmet (which I have already provided for) and a personal parachute, but I rather favor a BRS over trying to successfully bail out of a potentially spinning, tumbling aircraft.? FAR 103 allows whatever weight overage is necessary, and I'm sure modern engine choices would easily accomodate one.? Do you think the airframe is structurally robust enough to tolerate the dynamic loads involved?? BRS Corp would probably provide an analysis and recommendation if given a look at the pertinent plans, but that's way down the road, and I would really value your opinion (and of course obtain your permission) before I ever consulted them.

Bill