[DougM]

Now that would be fun but I would think that is just way too much airflow.

I am considering building a small box that will fit the stab and associated mounts/controls. With a fan from Princess auto it should be able to reach 100mph plus with the right shape.

[snovell]

Hey Doug

Take it to the NRC tunnel in YOW

[TBrum]

Doug... If you go to the NRC Tunnel, I'd love to come! Please, Please!!!!!!

I did testing there through University for a project I was on when I was in school... A whicked place for sure!!!!!

[cicopo]

My daughter had a part time job there which involved shooting frozen turkeys at canopies / aircraft windshields

[DougM]

LOL the frozen birds where an issue at first. They kept destroying the airplane windshields and structure. Then they realized they had to THAW them out first. Full size jets have windshields that can take a 4 pound bird at 250knots. As my friend likes to ask... "Is that the same a 250 pound bird at 4 knots?"

NRC is a great idea but even the low speed wind tunnel is expensive and hard to get into. I am still planning to build a 150mphish tunnel for flutter testing.

[TBrum]

This evening I started into the stab reinforcement project.

A few shots with the lower skin off. It's not as bad as I thought and will be a breeze to stiffen up.

That being said, I don't know if Peter got a lucky one, but I put the center bar in my bench vise and tried twisting and flexing the stab and it is rock solid.

[DougM]

Great shots Trevor. How much weight did you hang off it? Did you see any flex anywhere...at all??

From the photos it looks like the stab spar and the load path for the pivot are both cut at the intersection making both of them weaker. Is this area reinforced in the front or is it just all glued to the skin? Now that you have the skin off is there considerable flex?

If so, we might be finding a potential source. Delamination of glued/bonded structures in not uncommon and once it starts it can quickly progress. The ailerons on the Challenger did that over time...5000hours of hard flying.

Do you think this could be the potential issue?

[TBrum]

Originally Posted by DougM

Great shots Trevor. How much weight did you hang off it? Did you see any flex anywhere...at all??

From the photos it looks like the stab spar and the load path for the pivot are both cut at the intersection making both of them weaker. Is this area reinforced in the front or is it just all glued to the skin? Now that you have the skin off is there considerable flex?

If so, we might be finding a potential source. Delamination of glued/bonded structures in not uncommon and once it starts it can quickly progress. The ailerons on the Challenger did that over time...5000hours of hard flying.

Do you think this could be the potential issue?

Doug... it was insanely stiff with the skin in place. With the skin off, it is much weaker and now flexes where my finger is in the one picture.

I agree with you... I think it's an issue with delamination of glued / bonded structure. There is no reinforcement on the other side.

Should be a pretty simple repair. The most difficult part will be putting a new skin on it, because the original is garbage after trying to get it off, LOL

[KAPTAN KAOS]

Originally Posted by TBrum

Doug... it was insanely stiff with the skin in place. With the skin off, it is much weaker and now flexes where my finger is in the one picture.

I agree with you... I think it's an issue with delamination of glued / bonded structure. There is no reinforcement on the other side.

Should be a pretty simple repair. The most difficult part will be putting a new skin on it, because the original is garbage after trying to get it off, LOL

I would think the honey comb will compress over time and the bolts that go through into the joiner will become loose. Those two spars should be wood.....

too bad you didnt make a mold of the side you cut away.

[DougM]

I think that wood is the answer for sure. What would help also is to run a wood load path from the metal joiner to the main spar that runs along the top of the metal. This would relieve the stress put on the 4 bolts that seem to be transferring all the flight loads. This would be more effective that the single skin load transfer on the bottom.

Are you going to carbon fibre reinforce the spars? How about adding another spar that runs from the aft load/stab spars joint to the aft trailing edge at the root?

BTW what is the mass balance like, is it close?

Sorry for all the questions but I have 2 flying stab birds and well you know...learn from others...