RE: Shrike 40 with thinner airfoil
 

I worked as a tech in defense electronics, never did sales, I preferred working with data.

RE: Shrike 40 with thinner airfoil
 

I have heard people say that Balsarite placed in the key areas where fuel creep is a problem helps protect the wood. I use clear tape to seal seams that I know will fail soon enough.
I've never used "Blenderm" which is medical grade tape. Daven says that this is "the stuff".
I think Darrol Cady sells it, if you can't find it locally.
I also know of guys who can cover an entire wing in just a single wrap with the only seam right at the trailing edge.
I think I gave it a try 20 years ago and wrote off a roll of Monokote after that experiment was over.

RE: Shrike 40 with thinner airfoil
 

As an alternative to silk, a material you may want to try out some day on some project is uncertified ultralight grade 1.7oz Ceconite (dacron polyester) using thinned SuperSeam cement or nitrate. Seal with brushed..not sprayed.. nitrate (cross-coating, i.e. one brushed one way, the next brushed the other, repeat. It goes quickly). Then prime and paint with finish of choice, brush or spray.

Granted, the overall process may take longer than iron on, but I find it quite satisfying and the stuff shrinks drum tight (careful on some structures - watch your final temperature). Toughens up all the sheeted areas too.

So far I have covered two Demons and a large scale Tiger Moth with Ceconite and was very happy with the results. The .65 Demon is actually covered in certified grade (heavier, 3.2oz I think) but the net weight gain was nothing to worry about. The torsional stiffness it added was immense. And nitrate dope is just about the easiest painted material to work with there is, so long as you have a feel for how much to thin it.

RE: Shrike 40 with thinner airfoil
 

The blenderm is really the only stuff for sealing control surface gaps it is very flexible and even has good elastic properties as well. My wife is a nurse and has the stuff on hand, I have used it on just about all of my planes I think it is produced by 3M.

MJD,
I use nitrate to bond and seal the covering material I use I use a brush for the sealer coats.
For the actual finish I use butyrate dope and spray it on with an airbrush, using a fair amount of retarder to prevent blushing and to get a smooth flow out when applied. You have to put it on pretty thin as running is a problem.

RE: Shrike 40 with thinner airfoil
 

Flightskin looks like interesting stuff. Looks just like G10-FR4 Phenolic in thin sheets.

I am sticking with my decision on iron-on but there are many,many options out there.

Blenderm tape is great stuff but once it gets fuel penetrating the edges you might as well tear it all off. Then you have to COMPLETELY clean the surface it is going to stick to with acetone or ketone or it simply will not stick. This is true with many tapes and iron-on films. You gotta make damned sure there is absolutely no residue or oily film or it will not stay down.

RE: Shrike 40 with thinner airfoil
 

For anyone trying this - you have to use a brush for the nitrate sealer coats, to work the nitrate into the fibers and lock it in place.

On the .65 Demon I raided my paint shelves for materials, and ended up spraying a couple of coats of Lustrekote primer over the nitrate, a light sanding, then sprayed Hobbypoxy white over that with a touchup gun. Seems to be holding up fine. One day when I have a better place to spray I'll get a little more adventurous with paint finishes. i.e. more covering and paint finishes, less film. The Demon was done outdoors under our deck, but not ideal - you always get dust specks and/or bugs.

RE: Shrike 40 with thinner airfoil
 

Living in Ontario I would think working outside your paint would be saturated with blackflies and mostiques! Blood sucking vampires in miniature up your way!

RE: Shrike 40 with thinner airfoil
 

Yeah pretty much.. mosquitoes, blackflies, deerflies (biggest PITA on the face of the earth in my opinion), horseflies. Though they seem to be more interested in my flesh than paint - we have plenty of other critters that seem to be attracted to solvents though.

Last year we lucked out, the weather conditions worked out that the winged vampire outbreaks were relatively small.

RE: Shrike 40 with thinner airfoil
 

I grew up in the bush of Ontario. A friend of ours had a Fly-In Outfitters hunting and fishing camp. He had 2 DeHavilland "Beavers" and a Nordyun "Norseman". 1967 was my first year in the bush. That is a lonely feeling when that Beaver leaves knowing it wont be back for 8 days. But a week in "'God's Country" is pure heaven blackflies or not.

If the flies are bitin'...the fish are bitin' too! I'd rather deal with black bear than flies.

Black bear usually will only bite you once and you can't shoot mosquitoes with a 30-06!!!!!!!!!!!


HEY... Back on the subject of Shrikes.......Do you use MG servos on your high speed models?
I have been using the Spektrum DS-821's and having failures. Would like to move up on servos.

How about: Hitec Digital HS-5625's ? http://www.servocity.com/html/hs-562...tal_speed.html

But here again...metal gears?

I really don't think the mini size servos have a strong enough geartrain comparred to standard size servos. The mini's Hitec Digital HS-5245 put out good torque numbers at 6V BUT can the smaller gear teeth bare the loads for high speed flying?
http://www.servocity.com/html/hs-524...ital_mini.html

RE: Shrike 40 with thinner airfoil
 

I used a pair of futaba S3305's in the SD I am building, they weigh 1.6 oz, produce 124 oz torque at 6 volts and have metal gears. They are used a lot in cars and can take a substantial amount of abuse for a standard sizes servo.

RE: Shrike 40 with thinner airfoil
 

So you aren't too concerned about analog vs. digital?

RE: Shrike 40 with thinner airfoil
 

I have avoided metal gears, only because of the advice on RCU to avoid them with high rpm engines and light airframes with minimal vib damping. I have no personal experience to back up the claim that they can be problematic. There is logic in the claim that they can wear more quickly due to vibration, but I don't have a handle on how big a problem this is in practice.

There are a number of Demons flying around with HS-225's on the elevons. I wouldn't hesitate to use them on any sport .40-.50 powered version, but admittedly I would also use nothing less. In terms of torque, they have plenty for the task, especially if the builder is mindful of using maximum mechanical advantage in the linkage setup. I haven't heard of anyone stripping one yet, but that does not mean it couldn't happen. But there is no harm upgrading servos, there are plenty of reasonably priced servos with much higher specs. The 5625's look like a good choice.

RE: Shrike 40 with thinner airfoil
 

Not really and the digital ones are notorious for using a lot more power. For helicopters I can see where the digital ones are a better choice I not sure that they buy you that much for fixed wing. These are fairly substantial servos so even being analog they have more than enough grunt to deal with feedback from the surfaces as long as you have enough mechanical advantage for the controls and keep it so the servos have the maximum amount of travel without having to limit it within the radio.

RE: Shrike 40 with thinner airfoil
 

I have had carbonite ones strip out on me a few times.
One of the reasons I am using the S3005's is the best mechanical advantage I can get with the setup in my SD is 1.4 to 1 due to all of the linkage and horns being internal.

RE: Shrike 40 with thinner airfoil
 

Karbonite gears SUCK big time! I had a Great planes 1/3rd Pitts with 4 ailerons/4 servos. I thought I would save some bucks and use Hitec HS-485's at 80+ in/ozs of torque on each servo. I had the main output gear completely shear off on 2 aileron servos in one flight. Luckily I had one right servo top, and one servo left bottom, to get me down safely. I basically landed with the rudder,elevator, and throttle. This scenario happened twice before I decided "junk is junk"! Luckily I saved my Pitts from total distruction twice!.

Take my advise from personal experience....Hitec Karbonite gears are pure junk! Especially with vibration in the equation. I would not use them on a 1/2 A! [:'(]

I forgot I had 4 JR DS-821's in a box that came with my JR9303 2.4 DSM2. With one servo dedicated to each aileron on the new Shrike that is what I am going to use. I will go with a HS-5625 on the elevator and a HS-225 on the throttle. Tetra tank!

RE: Shrike 40 with thinner airfoil
 

The inner hole on the servo arm and 1.25 inches [or more] up on the control horn at the elevon = a real easy to fly plane, all else being equal. I can't guarantee what the servo travel volume will end up being from radio to radio..but ideally you want as close to 100% STV as possible.
So, what is this leverage ratio work out to...roughly 5:1..? Does that multiply into the servo's torque rating..? I think so.
Freakinfast talked me into buying some big, honkin' servos for the SD and I'm glad he did. They look pretty indestructable in our application where all we need is 1/8" to 1/4" of throw.
IIRC they weigh 2 oz each, with something like a 100-150 oz inch rating at 4.8volts.
I can't remember their model number, I'll go check if anyone is interested.

RE: Shrike 40 with thinner airfoil
 

Yeh...let us know! Some guys just don't realize just how much servo you need to fly at these speeds. Not your typical sport or scale application. The turbine/jet Jocks know it.

In/ozs. of torque is calculated at 1" from the center of the output shaft on the servo and as you have stated, those torque figures can be compromised with improper linkage setup.

1" to 1" arm to horn equals 100% more or less can be either advantageous or "whoa Daddy"!

RE: Shrike 40 with thinner airfoil
 

How embarrassing..!
I just looked inside the 200 mph plane and my memory isn't very good. The "exotic" servos I was talking about earlier with titanium gears are in a different plane I guess.
The ScreaminDemon has a pair of Hobbico CS150s instead.
[link]http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXNRT1[/link]
I was wrong about the linkage ratio too. I'm using the 2nd hole on the servo arm which is about 1/2" from shaft center and 1.25" up on the control horn..so the ratio is about 1/2 of what I mis-remembered installing. It appears I went with the 2nd hole on the servo arm to allow the pushrod to clear the servo hatch.
Anyway, these servos only have an hour or so of actual air time...so they haven't been tested for longevity yet.
I've had good results with Futaba 3010s in other planes that have way more air time.

RE: Shrike 40 with thinner airfoil
 

Mike Connor sent me a link to a servo force calculator some time ago, and using that utility he figured that the elevons on a Demon needed something like 47 oz-in at 30 degrees deflection at speed. Nobody I know deflects those elevons 30 degrees, so I figure in practice the requirements are quite a bit less. I also tend to take many of these utilities with a grain of salt, bit figure for mainstream applications they are likely in the ballpark. But.. as I am sure we all know or assume, there is more to the work a servo does than just predictable aero loads. Ask anyone who has used HS-55's for a while without incident, then bumps the rudder on the ground and strips the gears. Or station keeping an elevon that is trying to flutter at speed, absorbing shock loading from vibration, bla bla.

I'm all for oversizing servos within reason. Again, these days high output servos are so reasonably priced the decision to do so is pretty painless. I am not a big digital user, but plan to outfit a Demon with them sometime to see if I detect any advantage, and am planning to use them on my first turbine project. And use a freshly charged 2100 mAh Rx battery every flight!

RE: Shrike 40 with thinner airfoil
 

I use 30 degrees of throw a lot, even 45+ when doing flat spins as its elevator plus aileron. So even though 80% of the flight is low rate, I need max throw now and then too. My go to servo for years has been the 9202 Futaba. Their ratings are good but more portatantly I've never had a failure with one. Centering is as important as any spec on these planes too.

I just pulled a pair of 9202's out of a not used helo for my current DD/ Demon build.

RE: Shrike 40 with thinner airfoil
 

CBP,
Never looked at Hobbico servos before!

Those CS-150's look VERY appealing and digital.

I am going to use a 1000 mah 6V AAA NiMh pack from Batteries America ( E.H. Yohst ). Quite compact and a significant weight savings. I am always topping off my batts when at the field and monitor them very closely but still think the 1000 mah is sufficient. I use these batteries in all my Q500's with no probs of course my flight times or just over 1 minute per flight but usually allowing for 3 minute flight times I can easily get 4 flights in on a single charge and still have 50% reserve power left.

HR-4U-1000 1000mAh (AAA)
Super high capacity & high quality in AAA size

6.0v with leads: $19.00 BUY
6.0v with conn: $22.00 BUY

http://www.batteriesamerica.com/newpage8.htm

Way down, almost to bottom of page.

RE: Shrike 40 with thinner airfoil
 

Well the structure is done on my modified "Super Shrike 40". I need to do a little finish and shaping work on the rudders but now I will be proceeding on to installing the radio components and then a coat of Balsarite, sand the fuzz off, and cover. I was hoping to show the thinner airfoil with the frontal shot. I am proud to say this airframe is one of the straightest I have ever built and no fillers needed. Main color will be Ultracote "white" with flame red/yellow/black trim and black/white checkerboard on botton. This should be a good one! :D

RE: Shrike 40 with thinner airfoil
 

It looks GREAT !!!!!! Speedy

Please post some pictures on here when you have it covered. ;)

RE: Shrike 40 with thinner airfoil
 

Very nice!

RE: Shrike 40 with thinner airfoil
 

Just your plain old "Grocery Getter". I like it because it still retains an almost completely stock look.
Notice shorter and narrower nose and inset ailerons. I'm gettin' "wood" just looking at it! [>:]
The radio install and finish should go quick.

Bare airframe with engine,pipe,and spinner, is 35 ounces. Shooting for 3.5 lbs. RTF (dry).

This model will retain the same name as all my previous Shrikes...."Bad Hombre"!

Speedy-Gonzales