BigD_S2K

I am building up a ESM Hawker Typhoon with Century Jet retracts.This is my first experience with retract landing gear. With the retracts setting flat on wing mounting plate and gear extended I set the struts for axle alignment parallel with the center line of the wing. When the gear is retracted the forward edge of the wheel hit hard of the forward wheel well opening. With wheel axle set to 90 degrees reference the actuator body (landing gear assembly) there is no retracted interference, but my eye says maybe 15 degrees of toe in when gear is extended.. I think that would be like landing with the brakes on. As there is no real detail in the ESM assembly manual can someone share their experiences and suggest the maximum allowable wheel toe in. Also any suggestions as to how best to modify the installation without loosing structural integrity. Shimming would remove some of the forward gear rack and likely make the plane a bigger landing challenge (at least for me). I have reviewed the exiting forum for Typhoon builds and do recall a comment about wheel toe in but it didn't seem to be an issue. Thanks Guy

BigD_S2K

This must be a real strange question. However, I have established that when I install 3.5" wheels with approximately 5 degrees of toe-in the wheels clears the wheel well when retracted. I still wonder how this model was setup originally with the ESM air retracts. My Century Jets are electric.

da Rock

A couple of observations...

It's possible your question seems to have fallen on deaf ears could be it really isn't an aerodynamics problem, and is missing the appropriate population. Perhaps the moderator could be asked to move it to a forum that deals with warbird building problems.

As for your gear installation... If I understand what you're saying, when retracted the wheels hit the wheel wells at the front. All the other is description of how you can twist things to get them to clear on retraction. It really sounds like the gear assemblies are slightly misaligned.

As for toe in being a solution for a wheel to wheel well alignment problem, the proper fix should come from better alignment. As for what amount of toe in can be accepted when trying to solve a building problem, some of it depends on how far apart the tires are. Typhoons have decently wide stances. They also have forward angled gear, which throws caster into the picture. Good thing is the wheels appear to be straight up and therefore have zero camber. And they aren't steerable, so no ackerman problems. So truth is, obviously the problem is way more complex than just how much steering is your model going to get by with. And truth is, personal experience of ESM Typhoon flyers is needed far more than anything else. And they're more apt to be over in a more appropriate forum.

My gut feeling about your 5degrees is it's too much, and that a better way to solve the interference problem would be to adjust the gear in the wing to fit better.

BMatthews

Scale models tend to have taller gear too. So ti may need more or less than used on typical sport models.

I'd suggest re-posting over in the large warbirds area and get an answer from those who have dealt with models more similar to what you've got.

BigD_S2K

Thanks for your response, I'll post in the Kit build forum. The key is without something changing, 4 inch wheels will not clear the wheel wells when the landing gear is mounted to the wing provisioned mounting bracket. Review of Typhoon builds appear that the early model it not have plastic wheel well inserts. Some pictures show the inside of the wing. Not sure if these were picture of a ready to fly model or from models in build process. If I install 3 1/2" wheels they appear to just clear with proper alignment of the wheel, parallel to the center line of the plane. So that is the direction I/m headed, not sure I could tell the difference between 3.5 or 4" tires.

jester_s1

1-2 degrees of toe in is typical. Much more than that will cause extra drag on the runway, leading to rough takeoffs and noseovers.

BigD_S2K

Here is my summary for the original question about wheel alignment. Investigation shows the wheel axle can be aligned to the center line of the model and still retract with out hangup if 3-1/2" wheels are used. There must be a difference from the original ESM Air Retracts and the Century Jet Electric Retracts. i had to add 1/8" shim to the wing gear mounting plate to keep the landing gear from recessing too far into the wheel well when retracted.. The only other issue is the Century Jet Retract mounting flange holes are drilled for 4-40, 3mm screws will fit and are slightly larger. I think a 6-32 screws would be stronger, however the blind nut flange would be very close to the plywood mounting plate edge.