Jon,

Where is the CoG on the plane? Perhaps leaving the top wing solid instead of 'holey' would help with keeping some weight forward?

I thnk it would be better to stay with the original tail setup and add weight to the nose. Some planes and some designes just seem to require that to happen. Cutting, skimping or changing a design just to avoid a few grams is not always wise.

As this is the prototype, now is the time to make changes so I think lightening the tail is on the right track. Besides, anything you can do to lighten and reduce drag on a bipe is only a positive, especially at the small margins of error for a micro.

And..... the thinner tail surfaces just look right to boot.

Mike

Originally Posted by Obake

Jon,

Where is the CoG on the plane? Perhaps leaving the top wing solid instead of 'holey' would help with keeping some weight forward?

I thnk it would be better to stay with the original tail setup and add weight to the nose. Some planes and some designes just seem to require that to happen. Cutting, skimping or changing a design just to avoid a few grams is not always wise.

The COG is slightly forward of half way on the upper wing. Because of the aesthetic improvement on the tail I'm going to try it out first to see how she behaves in the air. We always have the fall back position.

I can't think it would cause any major problems but you never know unless you prototype! It also makes the build a little different and more interesting too I think. Hmmmmm - we'll have to see. Maybe a test flight this weekend.

Deleted

Originally Posted by deadbird

The COG is slightly forward of half way on the upper wing.

Now there's an interesting, often discussed subject - determining the Center of Gravity for biplanes! RCGroups details everything from using the "shadow method" to using the attached. Those discussions often include settings for the incidence of top and bottom wings (decalage), as well as for the horizontal stab ... which leads to Center of Gravity versus Center of Lift discussions .. which leads to dihedral discussions, etc, etc.

My friend Pete (mtflyr) who can make anything fly, including his many small WWI bipes, uses the following scientific method: tosses the model onto his well padded bed, adjusting components (mainly battery) until he gets a good glide. Further adjustments are made after flying.

What method are you using, Jon?

Gene K

I'm using the 'SAS' method Gene - Suck it And See!

Not having designed a biplane before I went off around the threads & looked at various CoG methods. I established from this that it should be somewhere slightly forward of the centre of the upper wing chord.

On the first build it turned out that the balance point was slightly behind the centre of the chord so I was prepared for a tail heavy aircraft on the maiden.

The first flight confirmed this as it took off after about a foot of runway. After wrestling it down gently I then start adding ballast until it flew right.

Because these aircraft are fairly tough I'm not too concerned about 'hard landings' due to instability so it give me every opportunity to employ the SAS method!

Jon

Originally Posted by deadbird

... the 'SAS' method - Suck it And See!

Must be an English expression.

Gene K

One of those phrases you grow up with, but nobody else knows what the hell you're going on about.

It made it into the Cambridge on-line dictionary though

...

Originally Posted by Obake

I shall endeavour to never post again in this thread.

No, please continue to contribute. The expression of my opinions was over the top, and I apologize.

Gene K

Well I'm not going to be doing any test flying this weekend on the Hawk as the wind has whipped up and we are forecast gales tomorrow.

I've also had a bit of an artistic block with the fuselage illustration. Stupid really but its a case of loosing the knack of it temporarily. Usually a good indicator that I'm knackered! Need to take a day off and go blow the cobwebs away I think.

400mAh 1s 30C Lipo samples arrived this week.

They are a good fit in the larger cavity of the P-6E and will mean, if used, the majority of the additional ballast in the nose can go and the flight times should be as leisurely as the aircraft is to fly.

All I have to do now is wait for the wind to die down.

Hmmm! Looks good! ...All I need now is a budget... of any kind :-)

Change of subject back to the topic of aircraft markings and pilots. Here's what the US Air Force Museum website says about the aircraft they have on display:

The only original P-6E still in existence, this P-6E appears in the colors and markings of the airplane assigned to Capt. Ross G. Hoyt, Commanding Officer of the 17th Pursuit Squadron, 1st Pursuit Group, based at Selfridge Field, Mich. in 1933. Edward S. Perkins of Anniston, Ala., donated it to the museum, and the Department of Aviation Technology at Purdue University restored it in 1963.

And here's a link to this info:

http://www.nationalmuseum.af.mil/fac...eet.asp?id=337

Finally, here's a link to my favorite photo of the P-6E in flight:

http://www.nationalmuseum.af.mil/sha...-1234P-022.jpg

Enjoy!

--Hatman

Originally Posted by Hatman

Change of subject back to the topic of aircraft markings and pilots. Here's what the US Air Force Museum website says about the aircraft they have on display:

The only original P-6E still in existence, this P-6E appears in the colors and markings of the airplane assigned to Capt. Ross G. Hoyt, Commanding Officer of the 17th Pursuit Squadron, 1st Pursuit Group, based at Selfridge Field, Mich. in 1933. Edward S. Perkins of Anniston, Ala., donated it to the museum, and the Department of Aviation Technology at Purdue University restored it in 1963.

And here's a link to this info:

http://www.nationalmuseum.af.mil/fac...eet.asp?id=337

Finally, here's a link to my favorite photo of the P-6E in flight:

http://www.nationalmuseum.af.mil/sha...-1234P-022.jpg

Enjoy!

--Hatman

I think Captain Hoyt will have to grace the Hawk with his presence in the cockpit. He certainly cuts a dash with his fine facial whiskers! Thank you for the further research Hatman.

I have finally managed to find some time & inspiration to continue the fuselage illustration. It is proving to be a really slow render but the detail is so wonderful, what with zip fastners, buckles and even a combination lock. The illustration below still needs a lot of work in the light & shade department.

Jon