Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

nice shrike 40 mod

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Old 09-16-2006, 07:11 PM
  #1  
rjbranchii
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Default nice shrike 40 mod

I maidened my first speed plane today, a Lanier Shrike 40 ARF. After reading some of the posts and based on my total hatred of tricycle geared aircraft I decided to do it with conventional gear. I used a light weight aluminum fuse gear mounted on a plywood plate between the 2 fuselage formers. I had noted on other threads that the plane tends to come out noseheavy (an understatement from my point of view) and I noticed people running out of elevator travel to attempt to flair the plane and needing to land it pretty hot. My suspicion was that the plane had to rotate more than needed to keep from impacting nose gear first. With a taildragger configuration the plane could land perfectly flat without need for a pronounced or for that mater any flair.

The ply plate I added to the bottom of the fuse spanned the fuse so that it loaded the triangular stock rails. I did not eliminate the fuselage bottom sheeting but epoxied right to it. I felt I could always cut thru if it turned out to be an issue, but my first landing, where I over flaired consisted of 3 or 4 hard bounces and no damage. The plate was beleveled front and sides and covered with white ultracoat. I used 1/4 inch birch ply and tapped the ply for 1/4 dia wing bolts. No blind nuts were used. The steerable tailwheel I mounted to a similar though thinner (1/8") ply plate at the back end of the fuse. Again it spanned the entire width so the loads went to the rails. I used an off the shelf steerable tail wheel mount and bent the wire above the pivot so that I could attach a ball joint coupler. The pushrod from the servo passed thru a plastic tube out the bottom of the fuse on the side opposite the elevator pushrod. Same type tubing for the pushrod to the elevator.

I attempted to favor myself as much as possible balance wise with location of the electronics. I placed a 1450 mah nickle metal hydride battery at the very back end of the fuselage. I used a futaba 8 channel receiver instead of a light weight unit and placed it just behind the servo tray. I moved the fuel tank back from the firewall to between the two partial bulkheads in the fues and place a thin ply covering for the opening in the firewall the fuel tank stopper normally passes thru. The canopy was not used since it would only be drag. The charger plug and switch were place behind the fuel tank just in front of the servo tray in the top deck. I also used all standard size servos since they are all aft of the CG. Normally I would have used mini servos on the throttle and tailwheel steering. I powered with an OS .46 AX. Using the standard muffler and a metal spinner (I will go to a more performance muffler, but wanted the metal spinner for the higher rpm's I'll be working towards in the future) did not work in my favor at this point. But I needed a starting point and needed to see if I was going to be able to handle this thing. I wound up building a plywood weight box full width of the fuse, 1.5 inches high and an inch front to back against the brace at the back of the fuse compartment. It is completely filled with lead to get the plane to balance per the plans. The flights today showed this is still just a tad nose heavy as the plane requires more down elevator to hold inverted than I prefer (like none and this took a fair bit) and a tendency to snap from inverted loops.

As to the maiden flights I flew the first with the book's low rate aileron and high rate elevator. I also had in reserve 2 inches of up elevator in a 3rd high rate just in case the elevator ran out. It was not an issue. I fly all my aircraft with -70% expo and -50% throttle expo. I also have -70% expo on the tail wheel. A very nice item for sudden runway direction change prevention. Each give me smooth control without limiting final control authority and also more linear power response on the throttle. I proped with an APC 10X8 prop and 10% nitro fuel. Takeoff roll was normal for a .40 size plane and very little elevator was needed for takeoff. All subsequent flights used low rate elevator for takeoff. One click of elevator and two clicks of aileron put everythings hands off in level flight. High speed flight was dead rock solid stable. Literally the same kind of stability I get form my pattern plane. That was very suprising to me. Rolls were axial but did require some elevator input to keep altitude, less than on most .40 sport planes but more than a pattern ship. Roll rate at low rates was very quick when thrown to full throw. The large amount of expo I fly with let me do very nice slow rolls. Just superb. The handling was the same at half throttle. There was no degradation in control authority. Slow flight showed suprising tenacity for the plane to keep flying. Stall only occurred with very high angle of attack. It was obvious that there would be no problem flairing with the book high rate elevator (1 inch throw) at this balance point... exactly per the book. Aileron response was good right thru the stall. At the stall the plane dropped the left wing just a little and flying speed recovered just by dropping the nose a little, even without throttle. Just about like flying a 100% scale piper.

As I mentioned there was a handling issue inverted. Normal flying was not an issue. Handling was very nice. When I pushed for a half throttle inverted loop the plane snapped out to the left. Recovery required about 50 feet of altitude and power and at no time was there any issue of safety of the plane. Verticle was totally unlimited regardless of when power was applied. Very interesting how very little kenetic energy was lost in full power verticle climbs.

Now that I had a good feel for the handling of the plane, I was ready to land. I did not have a good feel for how quickly the plnae would decellerate. Our club's field (Flying Wolverines, Algonac, Michigan) is 1050 ft long mowed, with another 1900 feet of 1 foot grass (yes its a former 100% scale grasss strip), so its not much of an issue. I brought the plane in at normal sport plane speed and leveled off about 200 feet from the threashold at about 50 ft til the plane seemed getting slow, still no sink. Then I nosed it down to regain speed and flaired about 12 inches off the grass. Too high. I eased the elevator with too little airspeed and dropped it and initialted about 3 bounces. Always excellent aileron control even then. No tendency to drop a wing. After retreiving the model (yes I hit the prop) and evaluating the gear and determining that there was no damage I gassed up and went again. This time I moved up the speed scale. I found one issue that can be a real issue in a plane like this. Doing Horizontal turn arounds is a high risk maneuver. The plane can visually totally disappear when it is pointed directly at you and you can cover alot of ground without much reference to the plane at these speeds. From my aerobatic flying, I rarely do horizontal reversals but almost always verticle reversals. This works out at our club but I have flown at some fields where everyone is expected to fly horizontal patterns. I would not want to to do that with this airplane.

The further landings were much different. Each was an easy greaser. The landing attitude as I had suspected was very flat. Hardly any nose up until the tail falls. The flair and landing looks very similar to a .60 size ultrastick taildragger.

In summary I would very highly recommend doing a tailwheel mod for this model. Future mods will be immediate wheel pants. The howl from the tires was obviously the highest drag issue on the plane. I'll also be going to an airfoiled carbon fiber gear to eliminate the drag there. Props and pipe are in the future. Tomarrow I'll move to an APC 9X9 prop as my next step upwards. But that will be after I have a header made. I want it to be directly behind the engine head for drag purposes. I do have access to a radar gun and when I get the plane towards its top end potential I'll get some readings. The plane is certainly faster than my .60 size scale aerobatic planes powered with .90 2 cycles which I have measured at 110 mph. Speed in level flight is dramatically faster than that. I fly a .90 size pattern plane with a Super Tiger .90 on a pipe. It is faster than the .90 powered .60 size extra's but this plane in level flight is dramatically faster. I have never measured the pattern plane, and I really don't intentionally go for speed with it because the ST .90 is a big torque motor and once the speed is there I'm really working more with the torque rather than rpms. One thing is sure. 2 wheel panted conventional gear offer ALOT less drag than three without pants and with one right in the prop wash. And its an easy lander in this configuration.

bob branch
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Old 09-16-2006, 11:32 PM
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Default RE: nice shrike 40 mod

Wow quite a review! We appreciate all the comments and recommendations- I think the 10x8 and 9x9 are a bit ambitious on the AX a 9x8 may be pretty good though! Ultrathrust or Jett-Stream muffler is the way to go- bolt and go!

Congrats on the maidens and mods---- I really enjoy hearing about these outside the box mods!

I cannot condone gear on this bird but hey!

Have a great weekend and let us know any updates!
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Old 09-17-2006, 07:09 AM
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Default RE: nice shrike 40 mod

Nice job!
Seems right on the money. I like the wheel pants idea.......

Wlcome to the society....

What do you estimate your landing speed to be?

randy
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Old 09-17-2006, 08:10 AM
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Default RE: nice shrike 40 mod

Razor:

The gear are I know an anathema for a speed wing. But its an arf and the covering will be toast in short time with gear landings. I have non geared 3d planes and I just prefer gear for our field. Indoors fine, but outside I like gear. I wanted to do retracts but there was not room in the wing and the fuse constraints prevented them.

I've used the ultrathrust pipe on 3D planes. It is hugely draggy though, moreso than the entire plane (except for the tires). Also the CG issues don't really make an ultrathrust ideal here. Karl Mueller makes incredible custom headers for pattern planes. I'm going to have him make a wrap around header for the motor so the pipe is on top of the fuse and directly inline with the head. He can do custom rises on the pipes so the whole thing will line up. It will be nice to have one of his pieces of art on display. On my pattern plane only the bend of the wrapped part of the pipe is visable thru the cowl. The .46 AX is a wonderful motor. I've had a couple years experience with it. Very powerful, extremely user frieindly, and comes onto power very quickly. I think a 9 inch prop will work well, but will explore some high pitch 8 in as well.

Landing speed was pretty much normal for a .40 size sport plane. Nothing at all remarkable as far as fast. I just had to wait with it in ground effect for the wing to finally pay out. Just floats there a little longer than a sport plane since there is so little drag. But it retained roll control there much better than most sport planes.

Randy:

Gotta thank you for inspiring me to this area of RC with you P-51/OS.91DF project. I have the same motor and an unbuilt F-15 ducted fan model for it. I was looking for what else to use it in. Thought I'd better get some speed experience before I put it in the nose of something with a propellor.

Can anyone recommend a speed plane with a fuse that is set up for rear exhaust from the get go that I can stick the OS .90DF in? I looked at Alley Cat but the fuse is pretty full and the OS.91DF is a very long motor with the rear carb.

bob
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Old 09-17-2006, 12:38 PM
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Default RE: nice shrike 40 mod

That is true... I figured you were not real concerned with drag since you got gear--- a wrap-around would be sweet!

Keep us posted
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Old 09-18-2006, 09:52 AM
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Default RE: nice shrike 40 mod

The power/rpm boost you get with the ultra-thrust or jett-stream far outweighs any drag delta beyond the stock exhaust system.

Razor is correct. The AX does not like rpm as much as the old 46FX. Stick with the higher pitch props - keep it in the 12,000 - 13,000 rpm range with the stock exhaust.

If you want something to put the fan engine in, look up Dan at Carolina Models (look in the vintage pattern forum). Get ahold of a T2AMII or brushfire or something similar from the 'good ole days' of pattern.
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Old 09-22-2006, 10:36 AM
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Default RE: nice shrike 40 mod

Sounds interesting. Any pics?

Eric
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Old 09-22-2006, 10:45 AM
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Default RE: nice shrike 40 mod


ORIGINAL: grumpE

Sounds interesting. Any pics?

Eric
look through the classic pattern forum....
http://www.rcuniverse.com/forum/foru...smode_1/tt.htm
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Old 10-01-2006, 03:47 PM
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Default RE: nice shrike 40 mod

Thought I would provide an update on a further mod. I flew it with wheel pants on the mains today. The wheels are still standard width wheels so I just put some pants on it from another plane. The speed increase was VERY marked! Air sound coming off the plane was probably cut more than half. Next step will be to go to prather metal wheels and a very narrow laminar flow countoured pant and to replace the metal main gear with airfoiled carbon fiber units. Love to have the telemetry unit some folks have but its just more than I can justify with the shrike. The speed increase was so dramatic that I am running out of power from the standard size futaba elevator servo to pull it out of a full throttle dive. I am running a 6 volt pack in the plane. So that will get an upgrade. I would not want to do anything higher than the low rate throw and it really isn't needed as long as the servo can handle it. The pullout was getting pretty wide today.

A note, the plane with the mod MUST be taked off with a fairly high elevator throw. Otherwise there is not enough pressure to keep the tail wheel gripping during the takeoff run. I switch down to the book low rate on climb out. Way I found out is obvious. Conclusion: the fuel tank clunk could not keep up with the cartwheels. Only damage was ruptured fuel lines and rudders knocked loose.

bob
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Old 10-01-2006, 04:07 PM
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Default RE: nice shrike 40 mod

Sounds like a lot of work for a not-very-slippery Shrike... I suppose you enjoy foolin' with it?
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Old 10-01-2006, 05:03 PM
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Default RE: nice shrike 40 mod

Wow! What a difference. I would like to see photo's of your final lg mods. Congrats on having the new mods working out so well. Can't wait to hear about it on the pipe.

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Old 10-01-2006, 06:28 PM
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Default RE: nice shrike 40 mod

Razor rcu

Well, this is my first foray into fast planes.... beyond pattern speeds. Yes I have my self imposed restriction of steerable landing gear. I looked at retracts but there was no sence doing that and staying in the cg range with this airframe.Still, planes can go fast with landing hear, as all the general aviation manufactures are leading much to their chagrin. Also going to standard gear in lieu of tri gear was a condition I placed on it. Being able to see the effects of aerodynamic clean up visably is also pretty satisfying. Not to mention that the plane is just plane a joy to fly.

I know this plane is not the fastest plane on the planet, but its a nice entry point into extreme speed. I know a .46AX is not a racing engine, but it is very flexible and reliable. While I have been in flying for over 50 years in modeling and over half my life in 100%scale I have only been flying RC for 3 years and I'm gaining some experience in going fast with the Shrike and flying without rudders in preperation for the F-15 ducted fan that is next on my building board. I tend to progress in things a step at a time. I have had the F-15 for over a year but decided there were too many new technologies to leap into at one time last winter. So I built a pattern plane to move my speed window up from the 110 mph range in my scale aerobatic planes and to learn how to work with a custom header and tuned pipe system. I built these on a system I already had alot of experience with, the Super Tigre G-.90. The high torque of the motor combined with the pipe is the recipe for a modern pattern plane and made for a very nice .90 size pattern plane. The speed and pipe are now as easy for me as my go to planes. The Shrike has let me go upspeed from the pattern plane and fly a more jet like control system. Now the ducted fan and retracts remain. The ducted fan will get tackled this winter. Its going to power a wind tunnel I'm building. By spring, the only technology that will be new will be the air retracts. That will make the F-15 a much easier issue.

I've become interested in extreme speed though thru the shrike. I have a considerable background in computer based fluid dynamics design along with considerable composite building experience larger than model systems. So I'm going to be working with one of the other fellows on the group here who has been working with a power system of interest to me in a clean sheet concept to go fast. I'm interested in developing something fast. I've enlisted a very experience racing engine specialist to the project to refine the power sytem that has already been worked with for a season by r-c-guy. Everything is open to clean sheet. There are some reall fast airfoils out there in the world and I have not seen any of them used in models yet. A symmetrical airfoil like a Shrikes is certainly no go fast airfoil. But essentially a modified flying wing it will have less tendency to a really fast planform or airfoil. I'm not interested in what limitations are presented by racing classes or rules. RPM under 20K is not going to do it. That starts to limit motor selections but the results that r-c-guy has had with DF rear intake engines has shown that power concept can even take a very draggy shape like a P-51 and do some pretty decent speeds. Putting that kind of a system into a dedicated speed shape should have alot of potential. Very few RC planes I have seen are truely streamlined for ultimate speed.

So I'm basically into it for the interest of learning what can be developed and doing it a step at a time. Standard off the shelf planes will not provide what I am interested in. But it is needed to have a starting point and the Shrike is a very nice one that can be made to fly alot faster than the ARF kit with very little work. That is the point of my development with it. Its worth it to me as a stepping stone and cause its fun! When the pants are only half an inch wide the plane will go alot faster yet. Aifoiled sectioned carbon fiber gear will ad another couple of mph. Course more power is available but that is not my purpose for the Shrike.. That's just my approach to things. There are lots of others that work in the world. I just have to have fun doing my recreation. The shrike is Fun and is now one of my go to airplanes. Problem is I have too many go to's to fit in the truck now. A good problem.

bob
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Old 10-01-2006, 08:57 PM
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Default RE: nice shrike 40 mod

Too many planes? Great problem to have! You have quite a game-plan there... What kind of F-15 do you have? TGA, Avonds, other? I had the TGA F-15 with a Byron set-up, not very fast but very cool and fun to fly...

I can see that you really enjoy the "process" which is great--- I am more of a plug-n-play kinda guy, building to me is boring and I am not good at it [X(]

Keep us posted on your progress!
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