Spuetz

Hi everyone,

thought Istart a new thread on this beauty.
It is a Nemesis NXT, meant to be driven by 2.2 kW brushless (or ducted fan glow engine). Produced by www.air-c-race.de here in Germany.
I have just received it this week. Now I am waiting for a wing replacement, cause mine has some flaws. The producer, Michael, agreed right away to replace it!Great service.
I'll keep you posted as I am progressing. Might be a while, though, since we're waiting for the rectracts (6 weeks estimated). I'll be travelling all of August, so it will be September before it's finished.

Anyhow, here are some first pictures. First two are taken by Michael Sieck, the producer and owner of air-c-race. (I guess he will not mind my taking his pics as I am praising his model). This is what mine will look like when finished. The others are of my model. I installed the tail surface and linkages/radio for it already. Servos are Hitec HS 5245 digi. One for each elevator, one for the rudder. Wing servos will be HS 5125 digi. Although, they don't fit into the very small openings in the wings. Hm... mightshrink.wrap them and glue them in...
Waiting for the motor to be delivered...

I will put in a Scorpion HK-4025-890KV on 6s 5000 Lipo driving an APC 9x10. According to my calculation that will give me 20.000 rpm, drawing some 98 Amps for 3.1 minutes of full power. Not all that long, but the prop wash speed will be 300 km/h (186 MPH)...

Any suggestions on this? Different set-up? Different motor? Experience? I am open and eager to hear what you think.

Cheers, Martin

Spuetz

For you guys who intend to install a glow engine, here are some pictures of the front end. You see that the cowling is anintegral part of the fuse - not removable. Might be a whole different challenge. Can be done, though but you need to be inventive...

Spuetz

Can't stop myself...

Here I put my Jett SJ 60 LX into it with a muffler. Now immagine this was a rear exhaust engine. Then this muffler would be about the right size. You can see how nicely it would fit. You can also see that the engine does not fit entirely under the cowling (third picture, top view - it is slightly out of centre). So you'd have to do some cutting of the cowling - which you would have to do anyhow for cooling...

Just how to fix the engine into the model? Well - that's for you to figure out and I am eager to see your solutions...

smoknrv4

My Feedback: (11)

Such a sweet lookin' bird! I would go electric I think with this one also.

Pylonracr

I don't know...I rubbed my christal ball really hard and I think Isaw a 46 size ducted fan engine in there. Will someone do it for me please??? Sweet looking bird for sure. I have seen a couple of them race here in Reno, and they are impressive.

Thanks for taking the time to post the pictures.

Spuetz

90 size ducted fan engine would be more like it...
Like the OS MAX 91 VR-DF

freakingfast

My Feedback: (3)

That is a beautiful plane. The website states a 4kW motor is required or is yours a smaller model? I'd question the size of the rudder servo you want to use, call me flutter paranoid. The elevator push rod tubes look like a couple of intermediary supports would be nice, even if the tubes are C.F. (paranoid again). Be careful how hard you pull your turns, they rated the model at only +- 10 G, very easy to exceed, at least for me.

Looks like it's moving when it's standing still! VERY SLICK!

Pylonracr

I have an OS 91DF that currently resides in a Little Toni. I thought it might be a little to large and thirsty. You stated that the plane is designed for an electric ducted fan engine. I am kind of an electric idiot. What size nitro engine is comparable to the electric? How heavy is the recommended battery pack. The 91DF burns about 4 oz a minute at full boil, so weight and size add up fast.Just how big is this plane?

Thanks for keeping all of us posted on this plane.

chalmrast

My Feedback: (1)

This guy stuck a 1000HP Garrett Turbo Prop in an NXT. Kevin Elderidge's "Relentless" had a Lycoming 540 with 600lbs of thrust and that plane would do over 400MPH. Since he lost his motor at Reno, he is putting a 720 in it. This Garrett will put out 3500lbs of thrust! ]

Also, only 4" of prop clearance on this baby!!

http://www.youtube.com/watch?v=kqZOuATiZeU

I like the kit in this thread. I've been working on a scratch-build on & off for the last year... all wood though. 399 Euro is way to pricey for me....

Spuetz

Hello,

Actually the website states that it can take motors between 1 and 4 KW:
"Motorisierung: Elektro 1-4 KW, 2 takt 8,5-10 ccm"

Also 2 takt 8,5 to 10 ccm means: Two Stroke, 40 to 60 size

I did the calculations. Anything beyond 2.2 KWwill require such a heavy battery (if you don't want to do 1 minute flights, that is!) that it becomes impractical.

As for the weights here is my calculation:

Battery: Lemon RC 6s 5000: 831 g (29.35 oz)
Controller: Kontronik Power Jive 120+ with cooling ribs: 163 g (5.75 oz)
Scorpion 4025-890KV:326 g (1.51 oz)
Total: 1320 g (46.62 oz)

Ok let's take the total and deduct the nitro motor setup:

Total: 1320 g (46.62 oz)
- OS 91 VR-DF: 707 g (24.97 oz)
- Muffler 133 g (4.7 oz)
- Tank, fuel lines 71g ( 2.5 oz)
Result: 414 g (14.6oz) of fuel

If the 91 burns 4 oz per minute, that gives you 3.65 minutes
The Elektro Version in this setup is calculated at 3.2 minutes...

However:
I have not calculated the extra weight for the receiver battery with the Nitro version. The electric version uses BEC plus a very small backup 5-cell battery. In the nitro version I would want double lipo batteries with lipo battery switch - the works. That'l bee some more weight. Probably the batteries would have to go into the tail, since the engine is so heavy up front.... So in any case you'll need weight in the tail. lead or bigger receiver batteries...

BUT:
The Electric Version is calculated at 2.2 kW
The 91 VR-DV is rated at 3.58 kW

So those Nitro minutes will be much faster ones. Or you downsize the engine, fly slower and longer... You do the rest of the math..

Spuetz

Hello Freakingfast,

Flutter is definitely a good call! However, the rudder is quite small - relatively speaking. And the Hitec Digi Servo can hold 110 Ncm! So if I pull the cables tight, it might not be a problem. I might exchange the servo arm for an aluminium or carbonite one, though...

As for the Pushrod support: I don't think it is needed - so far I have had no problems with other planes with fully "free floating"carbon pushrods. and besides: the tubes in the back, where the rods exit the fuselage, are quite long - about 4 inches...
We'll see... additional supports can always be added no problem...

Cheers, Martin

Spuetz

Hello Pylonracer,

it would be comparable to a 60-size ducted fan nitro engine.

And a small misunderstanding: I stated that it is designed for an electric motor OR a ducted fan nitro engine. NOT electric ducted fan motor. That would be too high rpm. Ducted fan electric motors are turning at about 30.000 to 60.000 rpm or even more...

Here about 20.000 RPM is the target. Why? Well for the props that are available that will give you some 190 MPH of prop wash speed (10 inch pitch is 186 MPH at 20.000 RPM)

The JETT SJ 60 LX would be neat for it. It builds quite low - fits almost completely under the cowling, is lightweight (513 g, 18.1 oz with muffler) and turns at about 18.000 RPM... on a 9x9. gives you 156 MPH prop wash speed.

Given the calculation above this would allow you to take
1320 total Electric
- 513 g Engine and muffler
-71 g Tank
736 g or 26 oz of fuel

the engine burns about 2 oz/minute, so that would be 13 minutes, almost a quarter of an hour, of full speed flying... If your nerves can handle it - well it'll be only 140 MPH or so...

Cheers, Martin

Pylonracr

I guess I need to learn how to read before I ask dumb questions. You did say electric OR ducted fan engine.

It looks like the 91DF is well within reason. I guess an extra few ounces is not that big of a deal. A micro throttle servo only weighs .6oz, lipo rx batteries are not that heavy, and as you stated they are moveable weight for balance purposes. What is the overall weight of this plane? I don't think even 5 or 6 ounces will make a huge difference in the way it flies, and the fuel will be gone to land so the landing weight will be low.

Keep up the good work

Scott

Spuetz

I am thinking about a hybrid.
not electric and fuel at the same time, but to build a platform that can be easily changed from electric to nitro and back... I would have to build the electric motor bulkhead removable, as well as the nitro one.. Hmmm - a construction challenge... a ring in the nose on which to bolt the electric bulkhead, another one further back for the nitro setup... Well, we will see...

Pylonracr

I looked at the photos you posted, this might not be too bad. I picture a bulkhead that would hold a nitro mount, but with a hole in the middle. A "box" type spacer could be made to mount the electric motor on, with mounting holes to match the nitro mount at the bulkhead. It would be fairly easy to makethe front cowl removable like most RC models. I was thinking about this yesterday when I was repairing my Twist that I PLANTED into the dirt... OOPS.

Wrap the nose in shrink wrap or similar. Suspend the model in a 5 gallon bucket a few inches from the bottom. Pour in some 2 part foam and let it harden. Pull the plane out and cut the nose off where you wantthe cowl line to be. Drop the now removed cowl into the plug you just made and mark it. Cut at the mark and cut again 3" or so up from that point. You now have a 3" thick reinforcing ring that perfectly fits the nose of the plane. Cut a bulkhead from aircraft plywood and use the "collar" you made to hold the nose to shape while you glue in the bulkhead. Do the same with the cowl if you need to glue in reinforcements or mounting blocks. From this point you could make multiple mounts to attach to your bulkhead.

If you don't want to cut the nose off your plane, install a Ring bulkhead and make all of your mounts bolt to the back of it. Kind of a sub-bulkhead arrangement. Every power package would install through the Ring you glued to the fuselage.

Keep us posted.

Scott

Spuetz

Hello Pylon Racer,
Ilike your second idea.. First idea ist a bit - uh... brutal. You'd have to make another cowling and all. Which can be done, but - lots of work...

One would start with the nitro setup. Once that bulkhead is made and the right position for the ring is found and the ring epoxied in, the box can a shaped to fit the electric motors... However, I would make a nother boltable bulkead with the box laminated to it for the electric setup.
In that way I would be able to leave the nitro engine on its (greasy) bulkhead, all with its throttle servo on the back. and swap it for the (clean) elektro bulkhead, with controller on its back. Neat!

Same deal for tank versus batteries: both can be fixed with velcro in the same place...

Well, we will see.

Cheers, Martin

airraptor

My Feedback: (66)

i started another thread down below about this plane. I was thinking of putting a OS 120 AX in it on a 14.5x14.5 prop. Now looking how small this plane is Jett 100LX FIRE sized engine would be a good choice with a 11x14 prop cut down to a 9.5x14 at around 16,000

Spuetz

HI,
where is the other thread? shall we keep them together - in one thead? I think that would be a good idea so everyone gets all the input and we don't have to jump back and forth.

Ihave an OS 90 AX now in my Kelly. Won't turn anything beyond 11.500 despite what they say in the advertisement.
Those OS engines are not made for speed and speed is what we need. So my Idea is - go for rpm! then prop accordingly.

But I curious to hear what your experiences will be. It might work after all...

Pylonracr

I also think it makes sence to keep it all in 1 thread.

As for the OS not turning high rpm, that is pretty much true. I run an ax55 that is slightly modified on a fun fly plane, and it turns about 15k comfortably, the 75 is fairly healthy but it doesn't rev like the 55. From the 90 up they are all ringed, so figure they are all torque motors. How much pitch do you need to go 150 at 12K That would be a funny looking prop...

Spuetz

You need 13 inch pitch to have a prop wash speed of 150 MPH at 12,000 RPM. For the airplane to actually go 150 you would probably need a prop wash speed of at least 170, depending on the prop diameter/airplane weight and drag ratio. So that would need a pitch of 15 inch.

airraptor

My Feedback: (66)

My thread I was just asking about this plane.

For your motor selection i think the 4035 scorpion would be better for a bit more prop turning torque.

OS engines can turn up if needed. I have ran my OS120 at 11,500 on the ground with a 13x11 prop on the stock muffler. The best speed came with a Jett muffler and a 14.5x14.5 APC at 9,200 This combo does 145-150 on the level and should be close to the same if not a tad better in this plane.

I would love to have a BVM 96 special though with a 11x14 cut down to 8.75x14.............

Spuetz

ok, i am going fully electric!
Ralph of powercroco.de built a motor for me, based on a Scorpion 4530. Here it is. (pictures)

Specs:

HK 4530 4+5x1,6YY<o></o>

11x11 apc sport<o></o>

about 17,100 rpm (static)on 35V + 150A.
weight: about 19.5 oz...

That's over 5 kw of power!

Flown on 10s
I'll start with 6s on 12x13 to try out how it flies, then gradually increase the number of cells (an weight with that) with smaller props...
the 6s 5000 that I have already weighs 31 oz...

The motor has a 10mm (0.4 inch !) shaft, tapered down to 6mm for the prop - with fat bearings! So the usual bearing-problem of the Scorpion motors won't be an issue here

markusvt

Does it come with any type of wheels and landing gear?

Spuetz

it doesn't "come" with it, but is prepared for the Behotec C 21 retracts...

markusvt

Looks like this one comes with gear>>>>>>> Nemesis Formel 1 Elektroversion?

I think on a lightweight 10S set-up this plane would really move, if the batteries would fit and it would balance OK.

The Behotec C 21 retracts fit Ok in the NXT-E? What size tires?

Wonder if it will be grass strip friendly?

Also wondering if the plane could be pushed to 200mph.

Any pictures of your hardware package that came with the plane?