Fritz (flying wing 1.5 meter)

[Konrad]

Just saw this come up on the sales site. I have to admit I love real flying wings.

PCM Fritz - Flying Wing 1.5 meter

You have not seen a plane like this one before! Introducing the brand new PCM Fritz flying wing!! Looking to add something unusual, fast and exciting to your collection? If so, the Fritz might be just the thing. The first time I saw sketches of this plane, and knew they were coming from the...

alofthobbies.com

It has been out for about 2 years. I'd like to learn what has been the experiance with the sliding pocket coupler used to drive the outer control surfaces holding up in the real world. It looks to me that they should perform much like the pocket we use with the RDS control systems.

And as NiMH are all but impossible to get, what in the way of a 2 cell Lipo/Life battery would fit in the wing?

 

[Haoyang Wang]

Well, I happen to have bought one on impulse... It's so pretty to see the wings of such a complex shape molded in one piece (bending up and down, while twisting to form the slight washout).

The kit comes with a 400mah NiMH pack.

The battery-receiver chamber at the nose is of about 120 mm wide X 40 mm long X 11-12 mm deep. It would fit in a single LiPo cell, or 2 LiPo cells connected in series.

According to the build instructions (https://www.pcm.at/downloads/Bauanleitungen/Fritz-BA-engl.pdf), in order to retain the structural strength, the hatch of the chamber (a piece of carbon fiber) should be attached with glue and not merely tape. Now this will make replacing the battery and the receiver a hassle.

There is a 3-pin connector coming out from the chamber. You can connect to it a charge plug, as well as a switch plug. (Difficult for me to explain clearly. See the instructions above.) I am thinking about using a magnetic switch instead of the switch plug. Then, I will have all 3 pins for battery charging. 3 pins are just enough for balance charge 2 LiPo cells.

What glue to use to attach the carbon fiber hatch to close the battery chamber. It should be stronger than tape, while still allow the hatch to be pried open when need to. CA glue, which can be softened by solvent?

 

[Chris]

I bought one as well... Was hoping to fly her at Los Banyos, but did not have time to finish her. I am planning to use a flexible glue like IC 2000...

 

[Wayne]

I think IC 2000 has one of the higher bond strengths for CA. I may be wrong..??

My thought was that the pocket is similar to an RDS, but looks to have lower loads on it. The cover for this is pretty thin carbon. I'm waiting for Chris to finish his so I can check out how tight of a joint it makes.

Battery - We ordered them with the NIMH pack as I knew they would be a pain to source. If you are going to use wide voltage servos, then I'd be tempted to drop in a small 2S lipo from Dualsky. Should last longer than the NiHM and is more tolerant of not getting charged for long periods.

 

[Konrad]

...

What glue to use to attach the carbon fiber hatch to close the battery chamber. It should be stronger than tape, while still allow the hatch to be pried open when need to. CA glue, which can be softened by solvent?

Acetone will soften CA and is still available in California, well fo now. Make sure there isn't any polystyrene near by.

 

[Doc J]

Use tape.

Doc.

 

[Haoyang Wang]

I managed to fit this 800 mah 2S lipo in the chamber.

Dualsky Lipo Receiver Pack 800mAh 7.4V

Designed for use in aircraft that use a separate battery instead of a BEC, to power the receiver and servos and any other accoutrements in a particular aircraft. This battery has a built in voltage meter that makes checking the pack voltage as easy as pressing a button. The meter outputs...

alofthobbies.com

In hindsight, the smaller 450 mah pack would fit more comfortably, but 800 mah still fits. Yay!

(I will drill 2 holes to let out the pair of antennae: one through the top of the wings, one through the hatch at the bottom.)

 

[Doc J]

I managed to fit this 800 mah 2S lipo in the chamber.

Dualsky Lipo Receiver Pack 800mAh 7.4V

Designed for use in aircraft that use a separate battery instead of a BEC, to power the receiver and servos and any other accoutrements in a particular aircraft. This battery has a built in voltage meter that makes checking the pack voltage as easy as pressing a button. The meter outputs...

alofthobbies.com

In hindsight, the smaller 450 mah pack would fit more comfortably, but 800 mah still fits. Yay!

(I will drill 2 holes to let out the pair of antennae: one through the top of the wings, one through the hatch at the bottom.)

I guess the two recesses are for launching?

Doc.

 

[Haoyang Wang]

I guess the two recesses are for launching?

Yes, they are finger holes, to be covered with a latex membrane. Fancy.

 

[Doc J]

Yes, they are finger holes, to be covered with a latex membrane. Fancy.

HI Haoyang,

Well it certainly is different. It looks like a theoretical design model from a paper on flying wings.

But...honestly if you look at the structure of your model, it seems to be a carbon pressed CNC foam core which is not only extremely strong, its pretty hard to do unless it really light like on a DLG for example. But I wouldnt mind betting that if you glued the battery hatch to the underneath, the increase in strength would actually be very minimal. You'd have to bond it on with epoxy and then glass it over to get any real reinforcement.

Thats why I mentioned tape because I guarantee that if you glue it in -even with 'soft' glue, then it wont be "strong" enough, and if you glue it in with 'hard' glue like epoxy, then you will have to open it up for some reason very quickly.

Looking forward to the flights!

Doc.

 

[Chris]

Very good point Doc, I am going to tape mine. I had been thinking this for quite some time, you just convinced me! I don't plan on it being the Lamborghini of my collection anyway... That role is saved for the Alpenbrise (if they ever get here...)

 

[jure]

... I mentioned tape because I guarantee that if you glue it in - even with 'soft' glue, then it wont be "strong" enough, and if you glue it in with 'hard' glue like epoxy, then you will have to open it up for some reason very quickly.
...
Doc.

this is one of the corollaries of Murphy's Law

 

[Haoyang Wang]

Thanks Doc. I agree with your assessment. The cockpits on many of my gliders are not even that strong as the front part of Fritz.

Besides, with this TWIN XLite radio coming out, I am reluctant to commit to a receiver now.

I wonder if the manual author was concerning on the stress from the bungee hook. (The hook mounting hole is just in front of the battery chamber in my picture.) As I plan to fly it mostly on slope, this is not a big issue for me.

Thanks again.

 

[Doc J]

Very good point Doc, I am going to tape mine. I had been thinking this for quite some time, you just convinced me! I don't plan on it being the Lamborghini of my collection anyway... That role is saved for the Alpenbrise (if they ever get here...)

Aha! so you are one of the first USA Alpenbrise guys!

You are going to like it...

More flights to look forward to!

Cheers,

Doc.

 

[Doc J]

Thanks Doc. I agree with your assessment. The cockpits on many of my gliders are not even that strong as the front part of Fritz.

Besides, with this TWIN XLite radio coming out, I am reluctant to commit to a receiver now.

I wonder if the manual author was concerning on the stress from the bungee hook. (The hook mounting hole is just in front of the battery chamber in my picture.) As I plan to fly it mostly on slope, this is not a big issue for me.

Thanks again.

Ah yes - I'd forgotten how much those European guys like those bungees.

I saw one come uprooted and hit the flyer in Australia once - actually he's a flying wing designer - Tim Harris. Not nice - you should have seen his chest 3 days later...ouch!

Doc.

 

[Raymond Gaskins]

Aha! so you are one of the first USA Alpenbrise guys!

You are going to like it...

More flights to look forward to!

Cheers,

Doc.

I, too, am looking forward to the USA arrival of the Alpenbrise (but do not know where Wayne is hiding them ).
Raymond

 

[Doc J]

I, too, am looking forward to the USA arrival of the Alpenbrise (but do not know where Wayne is hiding them ).
Raymond

They are residing in SF airport customs, Raymond. This is a frequent occurrence happening to companies who import a lot of stuff, and I bet Aloft imports about 90% of its goods.

But...I'm sure you will be happy when your shows up. Added to that I have orders for 47 more right now. There have been magazine write ups and reviews plus a lot of show flights in Europe, so they all know about the model.

Getting popular.

Doc.

 

[Haoyang Wang]

My Fritz had flown for 3 times before Christmas, all at Coyote Hills in the wind < 10 mph. I have been waiting for a more favorable wind condition, but it looks like Fritz won't get one for a while, so here is my impression so far.

With the 800 mah lipo mentioned above, my Fritz still need 42 grams of nose weight to balance, resulting in an AUW of 612 g. (The spec is "about 550 g".)

The first flight was in the very light wind, with the plan to throw it off the slope to check for the trims, then find somewhere to land below and climb down to retrieve it back up. It turned out I did not have to. Fritz somehow managed to keep all its 612g up in the calm air.

It is very stable. It is efficient like a DLG (only quite faster than a typical DLG). It loops fine after a short dive. It struggles to fly inverted, and also makes ugly rolls, but these observations are not fair, for Ahi would have struggled in the same air flying right side up, let alone inverted.

So we will have to wait for the "Ahi like" wind condition for fine tuning CG. So far Fritz has just flown around, magically in very light wind.

 

[Wayne]

Hey, that is not a bad start at all.

They are stout little birds. On the plus side, you may have a very rare plane on your hands! We imported 3 of them before PCM changed hands. I'm not clear if we can get them anymore.

 

[JustinMader]

I sadly missed the boat on this one, only discovered after they had all disappeared. If anyone has one they'd be willing to sell, I'm interested.