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SU-37 profile mid-pusher with lots of borrowed details

Old 12-01-2007, 08:02 AM
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Larry3215
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Default SU-37 profile mid-pusher with lots of borrowed details

I just finished my second SU-37 profile plane.

Both of them owe thanks to Steve Schumate for the general plan form altho I have changed some of the dimensions. I cant seem to follow a plan without doing something different

The first version was a twin pusher with the motors pivoting with the elevators to provide vectored thrust. It flew great and did some awesome hi-alpha manovers, but haveing the props waaaaaaay at the back was a real problem for ROG. The plane really liked to land at hi angles of attack which meant I had to have really looooong gear legs. Even then, I got prop strikes on every other landing. The long legs wer fragile as well and broke often. I scraped the plane because of the landing issues.

This new version was inspired largely by Kia's "Suriken" design.

http://www.wattflyer.com/forums/showthread.php?t=25367

What caught my eye was the mid-motor placement and his elevator layout. The mid-motor would allow for very hi-alpha landings and take offs without prop strikes and shorter landing gear legs.

The elevator design should allow for almost the same "thrust vectoring" performance as the pivoting motors did.

The final "borrowed" feature is how I mounted the main gear on the plane. Kosh built a Suriken and added wheels to his using a similar method. Its fast and simple. The other good point is it will be easy to cut the mains off and move them once I know for sure where the final CG will be.

I like my mains set behind the CG so that when the plane is sitting at hi-alpha the wheels are just a hair behind the CG. That way you dont get any sudden pitching down of the nose when the mains touch down in a hi-alpha landing. It looks a lot more scale if you can hold the nose up as the plane slows down. Its also easier to raise the nose prior to take off. That looks soooo cool

Here is a pic of the first one with the twin motors. I'll post some build pics in a bit.

I should maiden tomorrow if the weather co-operates, but its supposed to snow!

Larry

P.S. Sorry - no plans!

PPS - video at the end....
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Old 12-01-2007, 08:14 AM
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Build pics of the new version.

Larry
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Old 12-01-2007, 08:20 AM
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The power system is a CustomCDRom tripple running on 4S TP 1320 packs with a 7x5 APC prop.

Its pulling about 13 amps peak. The plan weighs 18 ounces all up now and the thrust is barely over 1/1.

I really need a hotter motor or Im going to have to go 5S. For 5S Id need to go from a Phoenix 25 up to a Phoenix 80 to handle the voltage. Thats waaay over kill tho.

I'll fly it this way and see how it does.

Larry
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Old 12-01-2007, 10:21 AM
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I forgot to mention one other thing I borrowed from Kai's Suriken - the servo set up Im using is the same as his. I have a single servo on each side driving both the elevator and aileron at the same time.

Im looking forward to trying this technique out.

By the way - my thrust is actually a lot more than 1/1 - once I realized I had the prop on backwards! They work much better when they are installed correctly!

Larry
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Old 12-01-2007, 02:24 PM
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Larry, I like your steering system. For some reason, I never thought about a servo right by the nose gear. I just remember seeing a typical trainer plane set up with one rudder servo and long linkages to nose wheel and rudder. I'm going to try your set up on my next plane.

Sorry to get off topic, but do you know a thread where you can post photos of a particular model or experiment to get some helpful feedback on what went right or wrong with it?

By the way, it is so gratifying to see a model table that looks exactly like mine. I thought I was the only one with a "creative ready" table.

Jeff
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Old 12-01-2007, 06:23 PM
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What?!? You mean everyones work tables dont look like that??

LOL I hadnt realized I posted any pics where you can actually SEE the table!

By the way - all those little bits and pieces that may look like trash are arrainged just so, in that particular order, so I can find them easily. They are actually parts for my next project

I have often done long linkages to either the nose gear and/or the rudder. In this case it just didnt work out because the prop is in the way of a nice straight run. I would have to use flexible Nye Rods or something similar and I hate those. This was easier and I needed the nose weight anyway, so it worked out well.

What type of model is it - trainer, sport, scale, jet, float plane?
What is it made of - foam or balsa?
Is it a scratch build or a kit or ARF?
What type of issues do you need help with?

The answers will help narrow down where your most likely to find good answers

I just remembered that Im using 4S and have waaaaay too many servos to run on the ESC BEC so Im going to have to dig out my external BEC.

Thanks for mentioning the servo!

Larry

Last edited by Larry3215; 12-01-2007 at 11:36 PM.
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Old 12-01-2007, 11:40 PM
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Default It flies!!

But I sure am stupid! I hilighted the statement above which I seem to have forgotten as soon as I typed it!

I got behind this morning trying to get out to the field befor it started to snow - and I did NOT make it. Somehow I completely forgot about the BEC

The first two flight (in the snow storm) went fairly well tho I had a "glitch" on the second one as I was taxiing back. I decided it was because my antena was pointing at the plane so I tried to squeeze in one more.... crunch!

Im now reminded that Depron gets pretty brittle when it gets cold too!

More details and a probably bad video later...

Larry
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Old 12-01-2007, 11:50 PM
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Originally Posted by Larry3215 View Post
What?!? You mean everyones work tables dont look like that??

LOL I hadnt realized I posted any pics where you can actually SEE the table!

By the way - all those little bits and pieces that may look like trash are arrainged just so, in that particular order, so I can find them easily. They are actually parts for my next project

I have often done long linkages to either the nose gear and/or the rudder. In this case it just didnt work out because the prop is in the way of a nice straight run. I would have to use flexible Nye Rods or something similar and I hate those. This was easier and I needed the nose weight anyway, so it worked out well.

What type of model is it - trainer, sport, scale, jet, float plane?
What is it made of - foam or balsa?
Is it a scratch build or a kit or ARF?
What type of issues do you need help with?

The answers will help narrow down where your most likely to find good answers

I just remembered that Im using 4S and have waaaaay too many servos to run on the ESC BEC so Im going to have to dig out my external BEC.

Thanks for mentioning the servo!

Larry
About time I see a cluttered work table Like mine That just means that something is going on, something is being made nice work Larry on the jet, Have fun, Chellie
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Old 12-02-2007, 01:13 AM
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Originally Posted by CHELLIE View Post
About time I see a cluttered work table Like mine That just means that something is going on, something is being made nice work Larry on the jet, Have fun, Chellie
Thanks Chellie

Here is a video of the maiden - in the snow storm! What some people will do to get a plane in the air!

Sorry for the poor quality. The only other person with me was my 6 yr old grandson and he isnt the most qualified videoographer. I had to sit the cam on the bench and hope for the best.

Its hard to tell for sure how well the plane handles but its not bad. Even with the wet snow build up I had no real problems once it was off the ground.

I do know the landing gear mains need to move forward closer to the CG. You can tell that from the near vertical take off! It didnt want to rotate untill it was at flying speed - then away we go!!

I discovered that small wheels dont so so well in wet snow. It builds up really fast! Thats why I had to walk out before and after the flights. I had giant snow balls on the wheels!

On the last go around when it crashed, the esc finally packed it in because I was running with 4 servos on 4S on the internal bec. Even the sub freezing weather couldnt save me from the blunder!

Im excited to get it back together and try again once the weather gets a tad better. This is possiblky the worst weather Ive ever tried to do a maiden in

The first part is the SU37 flights and crash followed by some fooling around with my Capricorn. It likes the snow!

Larry


Last edited by Larry3215; 12-02-2007 at 05:45 AM.
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Old 12-02-2007, 01:50 AM
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Wow You guys sure moved fast in the video It must have been cold there even snowing did not keep you from flying, I think the Capricorn liked the snow much better, keep up the great work, Take care & Stay Warm, Chellie
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Old 12-02-2007, 02:35 AM
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Hehe, if you think that's a messy work table, you should see mine (I'm so embarrased by it I would never post a pic :o), it has around 10 helis on it in various states of experimentation/repair (I say "around" because I'm actually not sure how many helis worth of parts alone there are on it ).

Ouch Larry, sorry to hear about the BEC, that's a bummer, at least the damage doesn't look too bad. I did get away with an SU-37 midprop running 4 S3110's on a Cool A12 at one point, but I was only running 3s (2 servos for ailevon/elevon, 2 servos for rudder/airbrakes , I had fun with that experiment).

-Kai
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Old 12-02-2007, 05:22 AM
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Yeah, the Castle esc's are fairly forgiving on the number of servos on 3S. Ive run 5 servos on a P10 and gotten away with it, but on 4S your going to toast the internal bec.

Im having issues with the video.... off to work on that... fixed I think.

Larry

Last edited by Larry3215; 12-02-2007 at 05:48 AM.
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Old 12-02-2007, 06:13 AM
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Originally Posted by Larry3215 View Post
Yeah, the Castle esc's are fairly forgiving on the number of servos on 3S. Ive run 5 servos on a P10 and gotten away with it, but on 4S your going to toast the internal bec.

Im having issues with the video.... off to work on that... fixed I think.

Larry
I'm actually moving away from PHX ESCs because of their partial throttle inefficency, but I do have to admit for a linear BEC they put up with being run beyond spec on 3s quite well. On my Maxir I run 3 analog and a digital tail servo off of a Spin11 on 3 and 4s (it has a built in 5.5v, 2.5A, switch mode BEC, but dang if they don't cost nearly 2x as much as PHX-10s do ). I've heard that some of the medium to large Eflite ESC's now have switching BECs.

-Kai
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Old 12-02-2007, 09:51 AM
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Now thats interesting. Castle is not perfect by any means, but in my testing, the Castle esc's did beter than the Jeti's and Hacker versions I have owned by a noticable margin - mostly at full throttle but also at lower throttle levels. I have always seen a good bit higher full throttle rpm at the same or lower amp levels.

Similar sized models from Castle have a lower forward resistance. That makes for lower losses in the esc across the board and higher voltage at the motor because the lower resistance means less voltage drop.

If your running them (Castle) on cheeper outrunner motors, the Jeti do seem to do better at smooth startup, but on the name brand stuff Castle are among the best Ive used. The only ones I like better are the Kontronic Jazz line. Kontronic is also worlds above Jeti on customer service in my experience. I like the Kontronic gov mode too. Not the easiest to program but doable.

Schulze are good performance wize but I hate the company (they screwed me over and have a snooty attitude) so I wont use one ever again. They are also even more over priced than the Jeti.

The one time I needed service on a Jeti was almost as bad as the Schulze eppisode so they are on my naughty list also. Dont even think about using the numbers from thier on-board data logging. They arent even close to accurate.

Ive had good luck with the MGM Compro line. The two I had ran very smooth but they were a tad less efficient than the Castle. Programming them is a nightmare tho so I gave them up.

I keep going back to the Castle because they always work for me but also because they are the only made in the USA controller you can buy at the moment. The other big reason is customer service. They cant be beat in that arena. No one else even comes close.

To me, once you add up the performance + price + service they cant be beet. The fact they are made in the US really caps the deal for me.

I am pasionately opposed to sending any more money to China, in particular, than I can help - especially directly to Chinese companies like UH/Hobby City etc, bypassing US dealers. US consumers are incredibly short sited and selfish for the most part. Its already hurting us and its going to hurt us even more badly over time.

As is common in RC (and life!) your milage may vary

Larry <sermon over>

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Old 12-02-2007, 10:02 AM
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Forgot - I havent tried any of the new esc's with the built in switch mode bec's yet. Im a little leary of doing that even tho I havent heard any bad reports.

Every single switching BEC I have ever tested - Medusa, Koolpower, Dimension Engeneering, FirmTronics and now Castle - ALL put out some noise and reduce range to one degree or another.

I worry about haveing one inside the esc. Id rather have it loose so I can move it around if necessary to reduce interference.

On larger models I just refuse to use a switching BEC. There is toooo much money up in the sky to risk it. Big birds can handle the weight of a liner regulator and rx pack easily and they produce no noise at all.

Larry

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Old 12-02-2007, 10:49 AM
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Originally Posted by Larry3215 View Post
I keep going back to the Castle because they always work for me but also because they are the only made in the USA controller you can buy at the moment. The other big reason is customer service. They cant be beat in that arena. No one else even comes close.
I "somewhat" agree to what you've said. I completely agree that Castle support is second to none in the ESC relm, but I have to say for mid throttle efficency I've found the Cool Running ESC's to be far superior and they've started selling again (albeit, at a higher price than before ): http://www.coolesc.com/

Mid throttle efficency I was comparing to Kontronik Jazz and Cool Running ESC's (I have a Jazz 40, Cool A12, and A25 that I love). On my helis I run high enough throttle when doing 3D that I don't really care about partial throttle efficency, but on my LAheli Sniper (Jazz40) I do love being able to cut back governed throttle without having to regear, and yet still enjoying the extended flight time at a flip of a switch (without burning up the ESC or motor ).

On my small helis, the PHX torque kick going to 100% throttle kills their already sensitive gyro tuning (neither my Jetis nor Cools have that problem). I still have a bunch of PHX controllers and plan on still using them in foamy aircraft, but don't plan on buying anymore until they fix some naggling issues (full throttle kick, gov spoolup speed, true auto ranging variable timing, variable optimized frequency, if they got 2 out of the 4 I would probably switch back ).

As to switch mode BEC noise, I agree that many make noise, but haven't had a single problem with the noise they make. I used to run 72mhz, but now run 2.4ghz across the board, even when I was on 72mhz none of the problems were traceable to BEC noise (but I have had to help other people with switching BEC noise, I'm very carefull about my electronics layout, I did circuit board prototyping for 2 years with 1.8 to 5.8ghz RF boards so I know a thing or two about RF propagation ).

While "made in the USA" may be important to you (and I can understand why, and have no issue with), I personally prescribe more to "made without reverse engineering someone elses hard work end to end" . Castle ESC's are great for the cost, have terrific running reliability, very good programming flexibility, have low resistance, and light weight, but I've just found that my specific applications are served better by more "specialized" ESCs (Cool, Jazz, or Spin, depending upon size and type of aircraft). There are of course exceptions to certain types of aircraft where I would use Castle ESC's, but currently I don't fly any balsa planes or large foamies (all my foamies have been under 11oz).

And I don't go by the logging in my Spin controllers, I have an Eagletree Micropower .

-Kai

P.S. Not that it matters, I haven't bought anything from Unitedhobbies, and really don't plan on it either, I prescribe to the buy "quality->buy once, buy cheap->buy twice" principle for all the purchases that are important to me. Oddly enough, my Castle ESCs are the least expensive ones I own, hehe.
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Old 12-02-2007, 06:41 PM
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Larry, you have inspired me to do more flying in the cold. Other than the brittling of the foam, have you noticed any other issues? Do the servos get draggy? Do your motors mind a bit of snow? I'm flying in Montreal, Canada and right now it is around 10 F. A bit cold but we'll warm up to 32 soon. When I have flown in cold autumn weather, I just keep the batteries in my jacket to keep them warm. Just wondering what happens to the LiPos when they get into the cold air of flight. I guess the only other issue is being able to fly with gloves on. The capricorn look pretty neat. Regarding buying parts, I started in this hobby with a parkzone Typhoon and then bought a Spectrum 2.4 ghz radio. Due to my lack of experience, I thought buying cheap and a couple of times made more sense until I was at a level where crashing was a more occasional thing. I am very tempted to go with a little screamers motor based on the performance of Kai's Shuriken.
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Old 12-03-2007, 03:14 AM
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Kai, your comments deserve a thoughtfull reply (and I have a question or two) and Im short of time and feeling under the weather at the moment, so let me take a break and get back to you later

Jeff - There are several things to be carefull of when flying in cold and especially in snow.

Cold makes the Depron more brittle, as I said, so things break easier but its not all that bad as long as you dont crash

The main issue you will have in cold weather is the batteries. They will act like they have a reduced capacity and run at lower voltages and in general just not put out as well when they are cold. Flight times will be reduced and power levels will be lower. It will feel like your packs are half dead if its very cold.

Its best to NOT push them as hard either when its cold. Its also a good idea to warm the packs up before you re-charge. I have heard some reports that its possible to over charge a cold pack.

I havent had any servo issues in cold weather but I suppose you could have problems if the gear lube got stiff or if there was moisture inside that froze. I havent flown in much below freezing temps. I break down before the planes do!

You have to treat snow just like water as far as water proofing. Snow will melt all over things and water WILL get into anything so treat with CorrosionX as if you were going swimming.

You couldnt see it in the video but wheels dont work so well on snow The Capricorn did fine because it has ski's in the form of the sponsons.

If you crash into a snow bank or in some way get snow packed into the motor, it could cause cooling problems if it blocks the air flow. It could even prevent the motor from spinning when you power up and burn out the esc or motor so be aware of that. I can see snow/ice mucking up gear boxes too.

Other than those small issues... its a hoot!

Larry
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Old 12-03-2007, 08:03 AM
  #19  
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Originally Posted by Jeff Waters View Post
<snip>I am very tempted to go with a little screamers motor based on the performance of Kai's Shuriken.
I wouldnt recomend the Little Screamer Kai is using for the Capricorn. Its too hi a Kv and spins too small a prop.

Id pick a motor that will spin a 9" to 10" prop on 3S for 100-200 watts. You can go up to an 11" if you want.

I suppose a DeNovo would work - barely - but not very well.

The MicroDan 2505 is my favorite "lite" setup by far. A CustomCDRom cool double would work very well too. For more power, I like the MikroDan 2510 or the CustomCDRom Tripple. The Torque motors also work very well or an Axi or Hacker or even an Eflight of the appropriate size and Kv.

Lately Ive been trying some of the Hyperion outrunners and Im very impressed with thier efficiency and quality for the money.

In fact, almost any motor other than a Little Screamer would be good

I dont like Little Screamers for a whole host of reasons (some personal) and refuse to recomend them.

They are over priced for the performance you get. There are a number of better made, better performing, same cost or cheeper motors out there - see above.

The customer service is spotty at the very best of times. Its not unusual to have to go public with your complaints to get Scott to fix a bad motor.

The specs and performance claims they make are always exagerated.

IIRC, the claims they have made for every single motor they have ever released have been challenged in one way or another. Many of them would need the motor to be opperating at 125% or higher efficiency inorder to achieve the numbers they promised.

I dont believe in dealing with a vendor that cant be honest with thier customers. Period.

Becides - they really do "scream". The noise is obnoxious IMHO

Other than those few little issues, they arent bad motors for the most part

Larry
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Old 12-04-2007, 06:47 PM
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Larry u will be the death of little screamer motors LOL.I flew a nylon IFO in the snow but i was having a problem with iceing it got heavy real Quick.Is the SU 37 that crashed due to besc probs. the 1st one or the 2nd
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Old 12-05-2007, 04:18 AM
  #21  
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Im bad some days

Planes like the IFO and my Capricorn and other similar plan form models are very sensitive to things like water and ice on the "wing".

Most of them are designed to fly with a CG at 15%-20% of the cord. That means that anything that covers the entire model - like water or ice - builds up at least 4 times more mass BEHIND the CG as it accumulates.

This can cause the CG to become tail heavy very fast.

It is especially noticable when the entire model is just one huge wing. Even a light coating of water/snow/ice on the Capricorn adds a significant amount of weight and causes a large shift in the CG durring the flight.

The SU37 in the above video in the snow is the newest one.

Its all repaired now and has a Park BEC added. I also moved the main gear forward about 2". That should put them closer to where the CG ends up after some more test flights.

Its been winter storm weather here abouts the last several days. Im hoping to get another chance to fly it in normal weather by the weekend maybe.

Larry
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Old 12-08-2007, 05:52 AM
  #22  
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I got 2 short flights in today over my lunch break. Im very very pleased

More flight reports later.

If anyone is interested, I got some really really bad video - with my cell phone cam sitting on a chair - of me doing some hi-alpha taxi runs today.

Its hardly worth watching, but Kosh was talking about doing "wheelies" down the runway in the Suriken thread and this thing does them very well now that the main gear are moved forward

Larry

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Old 12-08-2007, 08:41 AM
  #23  
Larry3215
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I got to make 2 short flights today - with no snow - and Im very pleased so far. Its not perfect, but not bad either.

The bad first - the rudders are not nearly as effective as I would like. They work well enough at speed, but I was hoping that at very low speeds (hi alpha and taxiing) they would get some more benifit from the prop wash.

They dont seem to be getting much if any that I can tell. Im going to re-do them with much larger moving surfaces. I may even move them closer together so they are more directly behind the prop.

The other thing that Im not 100% happy with is that its not heavy enough. Thats a wierd thing for a foamy pilot to say I know

Actually its a good/bad thing that may turn out more good than bad.

The thing that would be better with more weight is the landings. As it is now I have to slow it waaaaaay down to get it to land scale like. I really like bringing these jets in at hi alpha and greasing them in on the mains.

At its current weight, I have to slow it down too far to get the nose up as hi as I like it. I was hoping that using the reflex conected ailerons/elevators like Kai did would give it more appearant mass but its not quite enough.

The good thing about the wieght is that it will be easy to fly indoors the way it is. It has beautiful slow flight manners.

The weight will be an easy fix - I can just fly it with bigger packs out doors! I'll switch from the curent 3S 1320 packs to 3S 2100's. The extra 3 ounces should be about perfect.

The good stuff - As I said, its slow flight manners are very good. Virtually no wing rock in hi-alpha and very predictable controll. Its just needs a bit more rudder authority at low speeds.

It does an awesome Cobra! Much beter than my first one. At least its more controllable than my first one I was easily able to get good 90 degree rotation and have it stop with the nose straight up, then goose the throttle and off we go again.

The flips are very nice, fast and tight too if you hold throtle just a tad longer.

The other cool thing thats a first for me, is that it torque rolls! It does it super fast too. Looks very cool. I was also actually able to hold the torque roll and hover for a short time. Ive never done that with a pusher before.

Rolls are very fast and axial and it will even knife edge but it has some significant roll coupling at lower speeds.

Its almost impossible to upright spin. The rudders are blanked out by the elevators too much I think.

Over all, Im very pleased. I'll try to get some decent video tomorrow. Its supposed to be cold but clear and moderate winds.

Larry
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Old 12-09-2007, 07:13 AM
  #24  
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I got several flights in today - but I ran off and forgot the camcorder!

Im really happy. It does every thing very well except knife edge and spins

I managed to do several touch-n-goes today without letting the nose wheel touch the ground. That looks very cool

Im going out tomorrow and I will try to remember the camera!

Larry
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Old 12-10-2007, 01:14 AM
  #25  
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I went out again today and flew 3 packs thru it. Im even more pleased than befor I definately need to change the rudder and I also need to move the battery so its more centered. Latteral balance is off some.

Other than that its great!

Got some more video today that shows the roll rate pretty well and the tumbles and Cobra moves. I also managed to do several "mains only" landings and touch-n-goes without touching the nose gear at all

It was heavily over cast, so the video isnt great, but it shows well enough to get the idea.

Larry

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