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Dec 15, 2017, 03:10 PM
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turbonut's Avatar
On the 262 you want the tail pipe angled down not up. Up thrust will increase the pitch up swing at low airspeed. with the pipes angled down the plane will want to climb but not pitch nose up
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Dec 15, 2017, 04:40 PM
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Eric
Very nice work with the freewing 262 I looked at the link. I'm going to reread the link about flying your model. Looks like there's someone on your thread that is building the 1/6th scale 262 with glow engines, the plans I have call for one large glow engine in the nose or (2) smaller glow engines in the pods. Interesting. I thought about using a brushless prop driven motors in the nose but decided I needed a challenge never done EDF.

Turbonut
Any idea where one would start as far as incident angles on the pods in reference to the wing or datum line?

Thanks
Tony
Dec 15, 2017, 05:50 PM
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turbonut's Avatar
1 to 2 deg from the fuse zero line If i built it..wing 0 to +1
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Dec 15, 2017, 08:41 PM
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Turbonut
Thanks that's where I'll start
Tony
Dec 16, 2017, 02:44 PM
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Ed Waldrep's Avatar
Quote:
Originally Posted by cornj
Ed
Thanks for the input, didn't see any information on reducing the inlet in my research.
Tony
That's not surprising, most 262s have over-sized inlets, but 100% is all you really need and I've designed a lot of jets with that much area. My F-22 twin 480 45" long, my 63" E-Turbax, 51" 90mm F-18, 46" 90mm glass T-33, 51" 90mm F-4, 65" T-38 (yeah I had to cheat the inlet size to get 100%)...they all had around 100% FSA inlets. I've never went down to say 85% but that'd be as low as I'd go. If you're doing ROG with gear on a hard surface runway going small should be ok, but if it's a rough surface you man need all the low end thrust you can get. My friend's big T-38s with scale sized inlets ended up using aux inlets or a section of open ducting with a intake ring on the fan, but T-38s are hard anyway with such tiny inlets.

It depends on the fan size also, with the higher power available now at lighter weights, making a larger jet for a certain fan size than one would have used 15 years ago is doable. My glass T-33 has over-sized inlets for what would be scale (still it has 100% FSA for a 90mm Midifan) but it was designed near the end of the round cell nicad/nimh era. Now I'd probably use a 80mm (well I don't want to ever go to that size, more crap to buy) or a 70mm fan, or better yet make a bigger jet...bigger flies better! In fact I started a 60" long wood version of the T-33 last year.

But in the end, big inlets aren't a show stopper, I mean you've got an ME 262! Scratchbuilt or from plans, it's gonna get attention and will be cool!

I tried changing the thrustline of my scratch A-10 (my avatar) but it's been so long I don't remember what I did, up or down (I remember there being a thread years ago about what "up" and "down" thrust should mean, that's gotta be like 10 years ago LOL.
Dec 17, 2017, 08:49 AM
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Ed
Again thanks for the help, lots to learn.
I'm slowly working on the ME262, cut the wings out yesterday waiting for paint to dry on my Connie.
All have a good holiday
Tony
Dec 17, 2017, 06:43 PM
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AntiArf's Avatar
Built a number of 262s. The smallest seems about dead on and flies well, with the nacelles pointing downward at toward the front (downthrust) probably a good 3 degrees. Sitting on the nacelles, the fuselage is not level, with the tail a bit lower. May do fine with less if it wasn't a hand launcher that has to start off at low speed, where thrust induced pitch up is an issue. Another not so good solution is to use a further forward than ideal CG. Seems to be the case of the GWS 262 without downthrust. I noticed the comment about a model doing a full loop on launch, and then fortunately landing flat with no damage. There's a video of a guy who does that with a GWS 262, saves it, and keeps on going. Doesn't seem horribly tail heavy in flight either.

Built a second Yak 23 (off center thrustline subject) that flies well, after learning from the first build and not so good a flyer. Has a bit of speed related climb, but not bad with some positive stab incidence. Only thing I might have changed would be to move the battery rearward a hair. Haven't tried it, and the CG is a bit forward, but part of the perils of the low thrust line. The catch is it needs to be launched at half throttle along with a forward CG, or it will enter a climb stall. Had that happen on the first launch, fortunately landed with no damage. Once at speed, full throttle is not a problem. If the model was heavier then launching would likely have been a problem, as it would require more power to launch, where an undesirably forward CG such as on my first Yak23 would have been the solution. Lots of variables with these less than ideal thrustlines.
Dec 18, 2017, 07:46 AM
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Thread OP
AntiArf
Thanks for the input

My plan is as follows
In reference to the datum line
0 degrees wing
0 degrees horz stab
Make pods adjustable from -5 to 5 degrees (have no idea yet how I'm going to do this but that's the plan)
Tony
Dec 18, 2017, 10:30 AM
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Thread OP
Couple of quick questions regarding EDFs

On my multi motor prop models I always use standard rotation on the left wing and counter rotation on the right, this really helps with ground handling.

I see they make a 70mm EDF in reverse rotation and sell them in pairs (for a twin). Is buying this type of setup necessary or will buying same (2) normal rotation be OK? I didn't think jets had problems with torque.

What I'm looking at buying, don't want to spend a lot if this doesn't work out.
http://www.rc-castle.com/index.php?r...roduct_id=6825
http://www.rc-castle.com/index.php?r...roduct_id=7079
I have several ZTW ESCs and the programmer (really like these)

Thanks Tony
Dec 18, 2017, 12:00 PM
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4stripes's Avatar
The FW fans work and sound great. The only change I would recommend getting the 80amp Freewing ESCs to match. They will work for sure. Some ESCs can have issues running some outrunners.
As for your nacelles, I would try to make them more or less straight through with a neutral line. I think the FW 262 have them neutral. Yes some pitch up can be experienced if the throttles are advanced quickly at low speed but it hasn’t posed a problem on ours. Main thing is advance the motors to full throttle progressively and smoothly on takeoff to prevent it from leaping into the air at too low an airspeed.
Dec 18, 2017, 03:15 PM
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Thread OP
Thanks 4stripes
Tony
Dec 18, 2017, 06:16 PM
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turbonut's Avatar
I would not spend time on CR fans..If you have them use them
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Dec 18, 2017, 08:34 PM
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4stripes's Avatar
I would agree that CR fans aren’t necessary. My twins all have same rotation fans and no ill effect has been noticed. On the rare occasion the plane is pointed straight up with no forward motion, torque can cause the plane to roll but this also happens with single fan jets.
Since the set in the link comes with CR fans and the price is reasonable, there is no reason not to use them.
Dec 19, 2017, 08:22 AM
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Thread OP
Turbonut / 4stripes
Thanks for the input, what I needed to no.

My father flew the P51 (Air Force Reserves) in the early 50's and didn't like it, simulating combat over Lake Huron took a lot of physical effort, fighting prop torque, right leg was always sore after flight. 6 months later he was flying the F80 and said what a difference, no torque to fight. Later on he was flying the F86 and in this plane broke the sound barrier, Took the plane to it's max altitude then flew straight down with power full.

Tony
Last edited by cornj; Dec 19, 2017 at 08:41 AM.
Feb 10, 2018, 03:12 PM
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Thread OP
Update
ME262 is coming along.
This is the second wing that I built and covered (2nd wing covered with 1/16 balsa). First wing was covered with brown paper and I made a big mistake. I used gorilla glue to glue the paper on so thought I would wet the paper and attach, help cure the glue. What I ended up with was 2 bananas, both wings when dry looked like the up-swept wing of an airliner in flight. Looks like the paper shrunk after drying. I've used brown paper before without this happening but I didn't use any water, put it on dry worked great.
Weight as in picture about 4#, my guess after final sanding about 3 1/2# (I hope).
Tony


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