insalacosm

My Feedback: (1)

My father-in-law just gave me a VK Model's Nieuport 17 kitted ~1972. It's complete and everything appears to be in great condition. Any tips on the model? I'm planning to go with e-power.

Here's a picture of the kit and my current build, a Proctor Mini-Antic Bipe redesigned to look like a Jenny.

abufletcher

Tip #1: get the damn cat off the plans! You're a lucky guy to get a gift like that.

Steve Percifield

My Feedback: (14)

From the looks of the Jenny/Antic build, you should have no problem with the Nieuport. It looks great!!!

steve

www.hoosierdawnpatrol.com

insalacosm

My Feedback: (1)

ha, yes, the damn cat! I kept throwing her off the plans but my father-in-law loved it because this 20 year old cat (came with the wife) did the same thing to him when he would lay out plans many years ago at his house. Since he didn't mind I figured I would let her get away with it. Should be a fun build, although the kit is so prestine it's going to be hard to break into it.

My father in law is now tempting me with an offer to give me an old kit of the Proctor Nieuport 28 - he's trying to clean out his hangar - but it's a little bigger than I have space so I'm still deciding on that one.

Steve

Michaelj2k

My cat does it also. He thinks he's the QC inspector.

John Cole

My Feedback: (4)

Nice Mini-Jenny-Antic!! The 17 is really a nice gift, but you would LOVE the 28...

As noted, cats like paper...

Not my preferred method, but it does work:

http://www.youtube.com/watch?v=jm3dm5J5r0A

John

TFF

The only difference between the VK you have and the one Proctor sells today is the Proctor hardware; still the same great plane. I would build it stock and add your details.

Nieuport nut

My Feedback: (10)

Lovely gift. You are a lucky man!

I don't know how hung up you are on scale accuracy, but the VK N.17 could do with a little updating, (I have the plans). The Hardesty drawings from WWI Aero are probably the best, but the ones from the DataFile are probably good enough.

Martin

Bax

My Feedback: (11)

Balanced correctly, the plane will fly well. One of the members of our club in the 1970's built one. While it took quite a bit of weight to balance because of the very short nose, with a .60-size engine, it did very well. Weight will be your biggest enemy....try to keep it within the recommended range, if there is one.

insalacosm

My Feedback: (1)

I would like to build this scale so I'll consider doing minor changes to the outline if necessary. Since this is going to be electric, it may be tough to get enough weight in the nose, but I see some areas to lighten the tail such as pull-pull rudder.
Steve

Michaelj2k

On takeoff, apply power in a smooth motion and get the tail up as soon as possible to get rudder stering. Jamming the throttle forward will only result in a groundloop. Once in the air, it is very easy to fly. Coordionate your turns with rudder. On landing, wheel it on with a touch of power; get the tail down asap. Otherwise, it will nose over.

rowarrior

Hi guys, i wonder what is the status of insalacosm's VK N17 . I test flew mine last week, using much of the advise in this thread.

https://www.youtube.com/watch?v=pOIwNxijuYs

i put a 60 on the nose, yet she still wanted to climb with a bit, so i decreased the incidence of the top wing. for the maiden flight it flew with 0 degrees low wing, 1.25 degrees top wing, i changed it to 0 low wing and 0.5 top wing, lets see what happens. ive only flow it once .

buzzard bait

My VK N17 has an adjustable stab. That's the way to correct a trim problem. Or, judging from the video, just reduce the power. A 60 is an awful lot for this plane. Mine flies with a PAW 40 diesel over-propped with a 13x6. I have a battery box on the firewall next to the engine and all servos right behind the firewall. It balances perfectly with no ballast.

Jim

rowarrior

Hi Buzzard bait,

Thank you for your answer. However; my VK is not climbing because of the excess power. I reduced the power significantly in the air, and the angle of glide was not what it should be, as soon as she gained speed, the would pitch up.

I am thinking is either

a) wing incidence
b) tail heavy

Now, i balanced the plane per plans, so i think its unlikely it is tail heavy, but when i balanced it, it was perfectly horizontal, so it may need a tad more weight on the nose,

OR

the top wing is creating too much lift so the angle of attack (incidence) is high on straight flight. what do you think? when you balanced yours , is the nose a few degrees down?



the reason i used the OS Max 60 is because i needed the weigh on the nose. just like yours ,everything is behind the firewall, but it felt really good with that 60 on the front, flying at 1/3 of throttle the entire time.

what do you think/?

TFF

Assuming you used heavy Williams Bro wheels, them hanging low throws off the finger balance method. if its level, its probably tail heavy. The more power you have, or I should say use, the less incidence you need.

abufletcher

First of all, congratulations on your successful maiden! Judging from the video, I don't think it's tail-heavy. Being tail-heavy doesn't make a model climb; being tail-heavy makes a model sensitive on the elevator...and if it's too tail-heavy becomes extremely unstable and "porpoises" all over the sky. So it could be the incidences, but if those are as per the plan my first thought would be either engine power or possibly the thrust angle of the engine. ZERO thrust is fine. But make very sure there isn't even the tiniest bit of upward engine thrust. In fact, instead of adjusting the wing, you might also put a couple of washers under the top two corners of the engine mount. Of if the engine is beam-mounted on the VK design (as was common in designs of that generation) then place the washers under the rear positions of the engine flanges.

And yeah, I've never had a successful flight with the model hanging perfectly level. I always go nose-down.

rowarrior

makes sense, thank you.


So, I already reduced the top wing incidence from +1.25 degrees to +0.5 degrees on the top wing, but i have not flown it like that yet... Do you suggest i fly it like that, cut power high enough and see the glide path? and add some weight to the nose if i still see she is reluctant to lower the nose while gliding down? or i can revert my incidence changes and start by adding weight to the nose

thx!!

rowarrior

Hi Abu!

thank you!! well, the plans call for 0 angle thrust...i actually built in a -3 degree of thrust, or down thrust.

Now, the plans also called for a top wing incidence of +3 degrees to the datum, and i flew it with +3.25 , so after the maiden flight i brought it down to +2.5 and have not flown it like that.

My hunch was that a +3 degree incidence on the top wing would be too much..and 0 degree down thrust would make the plane climb. Do you agree with such hunch?

key thing to say is, when i balanced the plane, it was completely horizontal, where i would have preferred a little bit of nose down.

buzzard bait

I always balance the plane horizontally. I don't understand nose down. How is it balanced if it is a little nose down? No idea; you can't measure the angle, and even if you could, what would it mean? I think I can see horizontal pretty well. Then I know where it balances. If the plan shows a balance point, balance it horizontally at that point and fly it. Or do your own calculations and fly it using a calculated point. Then you can test it in flight to see how you like the balance point.

I do think the term "tail heavy" causes confusion. I agree that if a plane is tail heavy it will be overly sensitive on elevator in a way that cannot be corrected simply by expo or reducing throw. "Tail heavy" means that the balance point is too close to the neutral point, or is behind the neutral point, which makes it difficult or impossible to control. If a plane is "nose heavy" it means the balance point is too far ahead of the neutral point. Then the plane will need a more negative stab angle to keep the nose up, which means power changes will have a bigger effect on trim, drag will be higher, and the plane will land hotter. However, at a give engine speed, it may feel comfortably "solid" because it will not be very sensitive to elevator.

My balance point on my N.17 is at the point shown on the plans, which also corresponds to the point I calculated. I balanced the plane at that point horizontally. The stab is packed with some washers at the leading edge where it screws on, so it is somewhat positive compared with the plan. It was adjusted that way by a previous owner long ago, and I found that it worked perfectly. It's nice to be able to make that stab adjustment. On most models the stab is fixed.

The problem with shimming the trailing edge of the wing instead of shimming the stab is that you change the downthrust. Downthrust depends ONLY on the relationship between the thrust line and the wing. If you have no downthrust and you shim the trailing edge of the wing, you now have up thrust. As noted above, it's not a good idea. That's why I think that if you need to trim the plane so it doesn't climb so much, and you can't change the stab angle, it's best to just leave in the elevator trim. Sometimes it works to raise the trailing edge of the wing, if there is already some downthrust, you might not lose enough to matter.

Jim

rowarrior

hmm, thanks Jim, very interesting. let me give it some thought

buzzard bait

You're welcome; I wish I had some facility with computer drawing because I'm sure I could get this across much better with some diagrams.

The neutral point is determined by the wing area, stab area, wing chord and tail arm. It doesn't depend on any incidences.

If you picture the engine and the wing without any fuselage, then you will see that you can superimpose a fuselage on them in a way that will make the downthrust very obvious or hard to notice, depending on the orientation, but all the fuselage is doing is holding it all together. The stab/elevator gets trimmed as needed, so it's not in the picture.

Please ask questions if I'm not getting this across. Nice project, and a challenge too. I love Nieuports!

Jim

Michaelj2k

A simple test is to fly it to a comfortable altitude then push the nose down into a dive and release the stick. If the nose comes up, it is nose heavy. If the nose tucks under the tail, it is tail heavy.

buzzard bait

Yes, that's exactly what I do too. Trim for level flight at a cruising speed, then do the dive test. I like to see the nose come up slowly, which means moderate pitch stability. But I like to get close to the right balance point before I fly, which is why I always do the math first.

rowarrior

Hello guys, thank you for the answers. Before I address the dive test, allow me to bring this up:

So the plane is perfectly horizontal when balanced at the indicated AND calculated c of g.

Now, about the wing incidence:

I understand that if you increase the angle of attack of a wing, it will produce more lift (up until the point of stall). So, being that my VK N17 had a little higher angle of incidence that what the plans indicated, plus the fact that it really wanted to climb prompted me to think that by decreasing the angle of incidence I would see a reduction on this tendency to climb as the wing would produce less lift because being at a lesser angle of attack.

Opinions?

Now, it is the first time i hear of the "Dive Test" . So, are you sure? go into a dive and if the nose raises then it is nose heavy? wouldn't it be the opposite?

buzzard bait

The angle of attack depends on the relationship between the balance point and the incidence of the stab. Increasing the angle of incidence of the stab is the same as decreasing the incidence of the wing, except that you don't affect the downthrust.

It is important to forget about the fuselage, or a datum line. What matters is the thrust line, the wing and the stab. Think of them without the fuselage. Don't be misled by the angle of anything compared to the upper longeron, or anything like that.

If a plane is nose heavy, then when you trim for level flight the stab/elevator will have to create a downward force to compensate, otherwise the plane will dive. When you put the plane into a dive, the speed increases. The increased speed has no effect on the balance point, but it DOES affect the the amount of downward force at the rear created by your trim adjustment. So when you release the stick, the increased downward force at the rear (due to your trim adjustment and the increased speed) will cause the nose to rise.

Terms like "nose heavy" and "tail heavy" can be very misleading.

Jim