Stuka Stunt Main Forum · 18 of 18 known posts recovered
I'm seeking for a proven design for a SAITO .72 to compete seriously.
Any suggetions? Source for plans?
Thank you folks!
Claudio Chacón
ARGENTINA
Gordy
Gordan Delaney
Gordan,
Do you have some pics of the "Tony" to post?
Thanks,
Claudio.
I appreciate that...
Actually, I think there are a few design considerations that will eventually make the 4 stroke work to its full potential. I am currently in the process of modifying the Mr. Hyde/Dr. Jekyll concept to reach its full potential.
First off, we have to be real honest with ourselves. The current designs are not as "user friendly" when the 4 stroke is added without modification. I personally believe that simply adding a 4 stroke, moving the CG forward, and simply modifying the flap ratios (for example) have not worked to my satisfaction. This has worked well for Paul Walker and he has certainly been successful with the philosophy, but I do not think the performance in this configuration lends itself to slow controlled flight with blinding corners. This is imperative FOR ME if I am ever to win at the US Nats---HAAA!!!!.
The US Nats also demands small, sharp patterns that can be flown in open wind conditions (some very high). I observed several fliers at the Worlds that were flying very sharp corners and small patterns with the 4 stroke and none of the airplanes were simply 2 cycle airplanes with a 4 stroke added for power. All of the designs that I thought flew an "acceptable" corner for our US Nats had the wings moved substantially forward over their 2 cycle variants, thus re-centering the center of gravity to its appropriate position. This also results in a shorter nose which will certainly be stronger and less prone to vibration (more easily stiffened).
Secondly, the 4 cycles, when set up properly create a lot of thrust. They are not prone to slowing in the corner, even on low pitch. They simply power through the corner. This is good thing but can limit the "look" of the "flip corner" without some aerodynamic braking. This is also common among the piped engined airplanes of larger displacement.
Thirdly. In fact, I believe that aerodymic braking is imperative to the appearance of a "swivel corner". This theory, although not new as demonstrated by Al Rabe, Bob Baron, and even Billy Werwage is permanantly set in my mind. Recent experiments have shown me that a properly place CG and substantial flap braking results in much smaller, tighter, and more accurate patterns. Also, it allows more tip weight to be used with the aft CG, as much of the flap movement is lost when the CG is moved aft. Lastly it allows the builder to not to have to resort to building airplanes out of sticks that more closely resemble a free flight model, as the Berringers have done. While extremely effective, I believe the Berringer models to be too tough to build light enough (for the average modeler) to perform as well as the Berringer's models. The average modeler needs to be able to replicate the weight in his models over and over. I use foam wings and car paint becasue that is simply how I build models. Add these factors along with the Heavy 4 cycle engines, and I think you will find that will be pushing the weight limits of 2 cycle designs without modification.
The goal is to build an airplane that will have a certain amount of life and the Saito 72 is tough on airframes. I have personally BROKEN EVERY SINGLE AIRPLANE FOR THE SAITO 72 in the same spot. Right in front of the stab. I believe this is from the extreme control loads associated with the high thrust and forward CG (I have no proof). It has really become bothersome to spend all this time building and finishing models, using the same techniques as say, Doug Moon, only to see the airplane tear itself apart after a single season. For that reason you will need to build strong, which usually means more meat, which ususally means more weight.
Not to say weight is bad. I simply do not think that sharp corners and small tight patterns come from light airplanes. Of course, this is my personal view (one that I am sure many on this board will argue---Sparky). I have studied some great fliers on tape, and light airplanes do not necessarily equal blinding corners. Look at Brett Buck's airplane the Infinity. Small wing with big flaps with moderate to high wing loading and lot of controlled thrust. This is the formula that Al Rabe used for his entire career and I now firmly believe in it. Big Jim's designs are also based on this philosophy, and I beleive there are some incredible BJ designs that have even yet to see the light.
I think the LJ is particularly interesting.
[photo not recovered: 410d5b665e89885d.jpg]
Fourth, you will need a strong nose. Full Big Jim mounts 1/2" x 1/2" maple mounts and nose are minumum if you plan to get good runs and have longevity from the airframe. A carbon doubler and liberal use of veil or glass cloth on the outsde is probably not a bad idea either. Also, use only West Systems or equivalent epoxy for securing the mounts to the doublers as the heat from the 4 cycle will simply dislodge any common hobby epoxies. I actually glassed the entire inside of my nose on the MR. Hyde (several layers of 3/4 oz glass at the mount to doubler interface and bedded the aluminum pads into the wet glass. This has held (finally). I also found that alumnium pads cannot be used the same as with the 2 cycles. Normally, we pat the pad to accept the engine. This only resulted in 30 or so broken pads. I finally drilled through the pads and added wood inserts into the mounts. The engine is now bolted though the pad into the wood and no further pad destruction has surfaced.
The Zone 2, which is based on a Time Machine (90% PM) wing with slightly larger flaps would be a good choice. The CG is properly located and the TM wing is capable of hauling near 70 oz with the correct flaps with a very predictable flight (flat exits). I have considered substituting the Avanti 60 wing in a symmetrical configuration, as it is slight larger at the chord. The Zone 2 is a close cousin to Al Rabe's BBQB which is a delight to fly wit hthe Saito 72. His nose length is shorter, so in turn the tail moment is shorter, but all in all I think the balance of the two airplanes would be comparable. The main corresponding attributes is the small thick wing with large flaps, and a properly balanced CG.
There is certainly more than one way to skin a cat, but I think the stated design criteria would make for a very satisfying 4 stroke airplane that would be capable of flying at the highest levels.
Gordy's Tony flies incredible, but Gordy has extremely fast reflexes and can fly very quick corners (he is very underrated flier IMHO---practice more Gordy!!!) I simply do not feel that I have the hand/eye to get the blinding bottoms that he does at the speeds he does them (he IS AN EX-COMBAT FLIER YOU KNOW!).
All this being said I have been apprehensive to publish my designs formally as they have never really lived up to my expectations. In fact, I have been asked to publish the DR. J/Mr H but have not really had any interest until the plane is worked out to my satisfaction. It is tough working in a constant vacuum, as the 4 strokes at very high levels are few and far between.
Keep in mind the modern pattern was developed around a 4-2 break. The 4 cylce has no break, no second gear, if you will. This can lead to some problems if not accounted for in the type of 4 cycle run you choose and the design of the airplane.
I posted this on another thread:
My new "Alpha".
http://www.egpworld.com/ultrahobby/download/pattern%20plane%20ALPHA.PDF
It is somewhat of a departure from convention.
There also the Zone 2 which is based on a 90% PM wing. I thought about going to my own wing shape, something along the lines of Gordy's Tony but with a bigger flap and a little smaller wing.
http://www.egpworld.com/ultrahobby/download/ZONE2.pdf
There is also the current Hr. Hyde and Dr. Jekyll. The Dr. J has the wing moved forward 5/8" over the Mr. Hyde and uses a low aspect ratio stab and elevator. The Dr. J is almost complete. The Mr. Hyde continues to improve but has been suspect in many ways.
http://www.egpworld.com/ultrahobby/download/DRjandmrhyde.PDF
Hope this helps. Feel free to call.
972-235-9133
The City Smasher
If it helped? YOU BET IT DID! This is the kind of answer we always look for. Thank you so much Bradley 
I'll keep in touch, if you don't mind.
Best regards,
Claudio.
I am sorry Brad but I have to differ a little bit here. We do not build the same when it comes to nose construction. Not even close.
For any 4s plane I am going to build it will get 1/2X1/2 maple beams at 10" in length. This puts them over the top of the wing so they are joined together at the wing. I take the beams out to a 1/8" hard plywood nose ring. I use hard 1/8" plywood at f1 and hard 1/16" plywood at f2. In the tank area the beams are releived but they are not drilled. They are full size again after f2 and faired into the wing. Inbetween the beams is three layers of 1/16" 1/4 grain blasa with the grian traveling in three different directions. I also have put in pieces of 1/64 plywood in the layers. The beams are recessed down an 1/8" from the tops of f1 and f2 in the area above the tank and at the nose ring there is 1/4 grain 1/8" balsa making the crutch sit level with the top of the fuse sides. This crutch had been developed over many airframes and is working pretty good so far. It really held up so good during the Furias crash that the motor broke and the beams split but the main crutch was still kind of intact.
You use two peices of 1/4 plywood laser cut to fit into your fuse sides and up to the wing. Then I think you have a f1 and f2 plywood. Then you have a balsa piece on the bottom of your crutch as a tank height and support. And a ply nose ring. From your plan I think this is all you have.
How you construct the nose and how I do it are vastly different.
If you have planes breaking in the same spot, and you do, why dont you build them differently. You could put in 1/64 ply doublers along the back of your fuse in an oblong shape around the stab position on the insides and few formers in the top block and I bet that would cure you cracks.
I still think vibrations from the nose are the culprit. Vibrations will find the weakest spot and break it first and then move on from there. I have broken many planes and various spots and when it happens I try to redesign it as I go.
You told me once the deffinition of insanity is to try the same thing over and over expecting a different result. You told me this at the field as I complanined about my plane and did nothing to fix it thinking it would get better.
>
>Not to say weight is bad. I simply do not think that sharp
>corners and small tight patterns come from light airplanes
It sure soes make it alot easier though if they are lighter.
I know I have really light ones and really heavy ones. I alwasy do better with light ones.
Doug Moon
Hair splitting.
You still have almost zero experience dealing with the effects of Saito 72 on your construction. You had only a handfull of flights on the Saito 72 and then switched to the Saito 56. Even then you only had less than maybe 75 flights on that combination.
The City Smasher
NOT REALLY!
>
>You still have almost zero experience dealing with the
>effects of Saito 72 on your construction. You had only a
>handfull of flights on the Saito 72 and then switched to the
>Saito 56. Even then you only had less than maybe 75 flights
>on that combination.
That's fair to say for sure.
However with 72 and the 56 I never got any cracks or broken motor pads or any of that stuff. Never a loose motor not one time. I was only using a 14" prop at about 8600-8800 rpms. Maybe that rattles less than the way you have been running them as of late. I dont know.
You have complained about breaking pads and loose motors inside of ten flights, often.
I have been through that very thing with my first PA 61. Busted pads every 5 flights or so. Loose motor every other flight. Cracks everywhere. Stab cracked at the leading edge. finally a buckled wing. Changed building techniques of the nose and went to thicker top and bottom molds(3/32 over 1/16)and all of that stuff stopped.
Simple test. Take a peice of maple 1/2 10" long. Put one end your vise and on the other end haning out hang weights on it until it break. Do the same with your motor crutch. I would be willing to bet that maple outlasts it. What would it prove? I dont know. Probably nothing. I was just thinking outloud on how to test and see which is stronger.
You know we have been debating this one for a long time. 
But the difference in the way we build or noses is NOT hair splitting.
Doug Moon
Muy Bueno!!
1. Carlos Barabino P47 Saito 72
2. Carlos Barabino P47 Saito 72 2
All other shots, Claudio Chacon-Trivial Pursuit
Milton Graham\Proparc
By the way: how did you know about Barrabino's plane?
Cheers,
Claudio
No human on this planet goes through the pattern with a Saito 72 without me knowing it!!
Actually, I am Cuban,(My mother and father are Cubans. I lived there only shortly), and I have a particularly keen interest in Latin precision aerobatics.
Milton Graham\Proparc
Milton!! Así que sos Cubano!!! (I ASSUME that you speak Spanish..!)
Me encantaría que me mandes algunas fotos de tus modelos.
Y no me digas que no extrañás un buen Mojito!!
Seguimos en contacto cuando quieras.
Claudio.
Gordy
Gordan Delaney
Milton Graham\Proparc
In your e-mail, you asked about Reno racers. I am building a Critical Mass which is a modified Sea Fury. It isn't finished yet so I have no idea how it will fly.
I also have a Bearcat for the Saito 72 but cannot recommend its construction because of the complexity of the structure. This airplane was described by Godzilla in the post above as being a "delight to fly". This is a good competition airplane but difficult to build. In fact, there have been no successful BBQB Bearcats built without the help of a set of 20 construction videos. Laser cut parts and plans are available. I consider the plans to have insufficient detail to actually build the airplane and even with a set of laser cut parts, figuring out what to do with the parts would be practically impossible if a competition quality airplane is the expected result. Kyle at tanks-hangar.com sells the parts. I sell the plans as "pretty picture" for $15. The video set is also for sale, but I'm not pushing the sale because too few people would follow the construction as necessary to get the desired results. This Bearcat could be built as a "Rare Bear".
Al