Soaring USA gift certificate (Strega purchase?)

[Doc James Hammond]

Take it to Sunset and put a for sale sign on it. Might fetch enough to cover gas...

Hank

Best idea yet.

Doc.

 

[Konrad]

Gift certificates are a very cool thing if you use them correctly. For example, recently my girlfriend gave me a very cool gift for our anniversary.

If it was to SoaringUSA don't use it on RCRCM products!

Girlfriend and anniversary? Anniversary sounds like a wife.

 

[Konrad]

I need to start off by saying this is NOT a dig at the designer of the Strega. The Strega flew no worse than most other undersized tailed F3F racers of the time. In the intervening decades there has been a lot of development/understanding of the RC V-tail glider thanks to the men like Dr, Drela, Joe Wurts, Don Stackhouse. Most modern F3F racer are now coming in with a narrower V-tail junction angle (sub 100°), a lot more vertical side area, longer moment arms, all resulting in much more directional stability than the Strega.

The designer has complained that the tail decalage from the OEM (RCRCM) is not as designed. I have tried to modify the tail to meet the design criteria. I have to admit that I too found the OEM decalage less than optimal. But this had more to do with trim drag (needing down trim at my preferred balance point) rather than directional stability. I saw no real effect on the “ballooning” mentioned by the designer here. This looks to me to be a classic result of insufficient directional stability.

After the success of my modifications on the REDshift to the 96° V-tail I got to thinking, could this simple modification be applied to my Stregas?

This modification will be a target of opportunity as I’ll need to mix some catalyzed yellow paint to repair my Schwing Corsa 108. I really don’t think Strega can be made into a modern F3F racer. But it will be nice (I hope) to verify that the V-tail junction mod will be effective over more than just one design.

Now I have some concerns with bringing up the V-tail junction too much. Most theories that I’ve read don’t mention the efficiency losses (force over drag) in directional stability (yaw dampening) as a result of narrowing the V- tail junction. You can think of the V-tail in yaw similar to a bi-plane set of wings, with much the same efficiency losses and interaction problems. This is even more acute with lower aspect ratio tails we (I) have on the Strega.

But as shown with the REDshift the added vertical area from the narrowing of the V-tail junction does add real world stability faster that the efficiency losses from the narrower junction angle (inter-plane interaction). With the REDshift I notice a significant improvement going from 104° to 100°. Going from 100° to 96° did not have near the effect on directional stability. I again think this is as a result of diminishing returns as a result of the afore mentioned efficientcy losses.

With Strega I’m going to try to bring the V-tail junction up to slightly under 100°. I will be using the Yellow Strega as for some unknown reason it generally doesn’t fly as well as the White and Red Strega.

 

[Doc J]

I need to start off by saying this is NOT a dig at the designer of the Strega. The Strega flew no worse than most other undersized tailed F3F racers of the time. In the intervening decades there has been a lot of development/understanding of the RC V-tail glider thanks to the men like Dr, Drela, Joe Wurts, Don Stackhouse. Most modern F3F racer are now coming in with a narrower V-tail junction angle (sub 100°), a lot more vertical side area, longer moment arms, all resulting in much more directional stability than the Strega.

The designer has complained that the tail decalage from the OEM (RCRCM) is not as designed. I have tried to modify the tail to meet the design criteria. I have to admit that I too found the OEM decalage less than optimal. But this had more to do with trim drag (needing down trim at my preferred balance point) rather than directional stability. I saw no real effect on the “ballooning” mentioned by the designer here. This looks to me to be a classic result of insufficient directional stability.

After the success of my modifications on the REDshift to the 96° V-tail I got to thinking, could this simple modification be applied to my Stregas?

This modification will be a target of opportunity as I’ll need to mix some catalyzed yellow paint to repair my Schwing Corsa 108. I really don’t think Strega can be made into a modern F3F racer. But it will be nice (I hope) to verify that the V-tail junction mod will be effective over more than just one design.

Now I have some concerns with bringing up the V-tail junction too much. Most theories that I’ve read don’t mention the efficiency losses in directional stability (and yaw dampening) as a result of narrowing the V- tail junction. You can think of the V-tail in yaw similar to a bi-plane set of wings, with much the same efficiency losses and interaction problems. This is even more acute with lower aspect ratio tails we (I) have on the Strega.

But as shown with the REDshift the added vertical area from the narrowing of the V-tail junction does add real world stability faster that the efficiency losses from the narrower junction angle (inter-plane interaction). With the REDshift I notice a significant improvement going from 104° to 100°. Going from 100° to 96° did not have near the effect on directional stability. I again think this is as a result of diminishing returns as a result of the afore mentioned efficientcy losses.

With Strega I’m going to try to bring the V-tail junction up to slightly under 100°. I will be using the Yellow Strega as for some unknown reason it generally doesn’t fly as well as the White and Red Strega.

History:

As far as I have been able to ascertain, the Strega was "Gotten to" by an "unknown" German Gentleman (I know who he is) after I signed off on it and I had no idea that it might have been modified until people started to ask me why it would not turn properly and would shoot off into the wild blue yonder - If it didnt stall that is. Also why it would not fly straight and level without constant dabs of down or with a CG so far forward it turned into a wet sponge.

I did not actually examine a model until over a year after it came out as the test plane I was promised never came.

Examination results - Apart from the usual low standard of construction common to most RCRCM models:

• The aeroifoils "might" have been mine though I'm not sure as later they were claimed to have been designed by RCRCM ("RCRCM Special") so that's open.
• The wing and tail had been given an angle of attack of at least 2 degrees, which if in fact the airfoils were mine would effectively kill most of its turning ability and the straight line speed.
• On the fuselage of the one I looked at, it was *banana-shaped having been leaned up against a wall or something when it was still green out of the mould.
• The vee tail angle on the original design was 102 degrees and the same on the production model.
• The Vee tail area was the same as the orginal design.

*This is something to check on all Stregas as it only takes a hair dryer to fix - but don't leave it out ithe sun as the resin quality was inferior and highly heat sensitive so it will just "banana up" again.

 

[Konrad]

History:

As far as I have been able to ascertain, the Strega was "Gotten to" by an "unknown" German Gentleman (I know who he is) after I signed off on it and I had no idea that it might have been modified until people started to ask me why it would not turn properly and would shoot off into the wild blue yonder - If it didnt stall that is. Also why it would not fly straight and level without constant dabs of down or with a CG so far forward it turned into a wet sponge.

I did not actually examine a model until over a year after it came out as the test plane I was promised never came.

Examination results - Apart from the usual low standard of construction common to most RCRCM models:

• The aeroifoils "might" have been mine though I'm not sure as later they were claimed to have been designed by RCRCM ("RCRCM Special") so that's open.
• The wing and tail had been given an angle of attack of at least 2 degrees, which if in fact the airfoils were mine would effectively kill most of its turning ability and the straight line speed.
• On the fuselage of the one I looked at, it was *banana-shaped having been leaned up against a wall or something when it was still green out of the mould.
• The vee tail angle on the original design was 102 degrees and the same on the production model.
• The Vee tail area was the same as the orginal design.

*This is something to check on all Stregas as it only takes a hair dryer to fix - but don't leave it out ithe sun as the resin quality was inferior and highly heat sensitive so it will just "banana up" again.

Did you ever have the "privilege"of owning a Strega (flying your own ship)? If not that 34 sec time is real good for a borrowed ship!

Well, well I measured the V-tail junction and one of my Stregas at 105° and the other at 103°. Now I have been moving the small alignment pins around, but have not (well tried not ) to mess with the V-tail joiner system.

Now for full discloser; the better flying Strega (white and red) is at 105°. And the slightly less controllable Strega the (yellow and black) is showing the 103° V-tail. Don't think the V-tail junction is what is responsible for the different feel. But I'll soon learn if bringing the Yellow and Black Strega to 99° will help or hinder the directional response.

 

[Konrad]

Well, well, I just did a few test flights with the new 96° V-tail on the Yellow and Black Strega. It is now 3 for 3 with the narrower V-tail junction aiding in the directional stability of the F3F V-tail models! I flew back to back flights with the "stock" V-tail junction angle of 105° (measured) White and Red Strega. While not a night and day improvement it definitely is a noticeable improvement!

Lift was light (read too light), I'll need to do more testing to try to get the most out of this new configuration with modification to the radio set up. Now I wasn't racing, rather just turning around the pylons (low and fast near the ground). Having the pylon and the ground as a reference it was easy to see that the 96° V-tail was better set up than the 105° V-tail Strega.

You can see with the photo I now have a bit of a gap in the fuse to tail junction. I'm thinking of taking care of this with some filler. I'll do this at the same time I clean up the V-tail mounting rod break through. This was a good idea I got from the designer in his instructions for the Redshift build. The RCRCM V-tail receptacles often broke free inside the fuselage. Note this model has the 1.5mm decalage modification.

 

[Konrad]

In the old days I don't recall failing the fuselage seams. Yes, I destroyed many a fuselage but for the most part the seams did not split. These older fuselages had what is known as fiberglass tape joining the seam. This amounted to some real significant fibers crossing the seam.

Today we see a process called the wet seam. This uses some of the fuselage layup that is proud of the mold to span the mold seam line. This sometimes works, but often it is just the added adhesive that is bonding the fuselage halves.

This is of RCRCM manufacture and is not what Aloft Hobbies sells. I'd like to see in Aloft's sales page some details of the fuselage seam. I'd also like to learn if the fuselage of the models Aloft sells was made with a bladder to push the fibers down along the tail boom and vertical fin (if it has a fin).

Please note that this Strega fuselage has been abused!!! This failure might have been damage I overlooked when making previous repairs.
But the last set of flights where made in low lift conditions. This means that I actually had some ground speed when landing. This meant that the fuselage would be jerked side to side as the wing tips came to rest. The result is the the wing root leading edge would try to pinch the fuselage causing the fuse to fold along the seam.

What kept the fuselage from tearing apart is that this Strega has a full length nose web (servo tray) that goes back past the wing LE. This tray and the ballast tube are what supported the lateral landing loads.

 

[blitzu2]

Konrad or James Hammond...you guys still out there?
I'm going to purchase a Strega II .....glass/carbon version...
Anyone flown it or any impressions a out it?
Cheers!

 

[Konrad]

Don’t do it!!! If given to you, you might get some value out of it.
Really, you didn’t already get this from the tone of this thread?

I'm not aware of any changes to the management of RCRCM to warrant any reevaluation of my position on the quality of RCRCM's products.

For the same (or close to) price point the TJIRC product line is far superior. I liked the Alpha 2.8 as a good sport /F3F ship.

Read my thread on the Alpha 2.8 here.

 

[Doc J]

Konrad or James Hammond...you guys still out there?
I'm going to purchase a Strega II .....glass/carbon version...
Anyone flown it or any impressions a out it?
Cheers!

Hey Blitz - even if you get a really well made version - if there are any, the basic model has a huge flaw in that RCRCM - unknown to me at the time - modified the incidence. There actually should be no incidence so the tailplanes need to be moved up at the front in order for it to have any chance flying well. Its a serious mod and if done wrong could be pretty catastrophic. You probably dont need that kind of hassle.

I'd get a Corsa - 2.75 M, well made by the new guy and flies like a bird.

Cheers,

Doc.

 

[Konrad]

The Strega and Strega II are different models. But the quality of the RCRCM product is the same.

The Aeroic product line is a huge step up in quality with the resulting price being way outside the price point of the sub par RCRCM product.

Like other's I would recommend moving up in quality from the RCRCM product line. How far up is between you and your banker.